WO2013008408A1

WO2013008408A1 - Charging control system, battery pack and charging method

Info

Publication number: WO2013008408A1
Application number: PCT/JP2012/004289
Authority: WO
Inventors: 忠大吉田
Original assignee: Ｎｅｃエナジーデバイス株式会社
Priority date: 2011-07-08
Filing date: 2012-07-03
Publication date: 2013-01-17
Also published as: JPWO2013008408A1; JP6124346B2

Abstract

In order to bring a plurality of battery units (battery cells) connected in series close to full charge without overcharging the battery units, a battery pack (10) is provided with a plurality of battery cells (100), a measurement unit (300) and a control unit (400). The plurality of battery cells (100) is connected in series. The measurement unit (300) measures the voltage of the battery cells (100). The control unit (400) controls charging of each battery cell (100) on the basis of the voltage measured by the measurement unit (300). In addition, the control unit (400) identifies the cell with the maximum voltage, which is the maximum voltage, on the basis of the voltage measured by the measurement unit (300) when the battery cells (100) are being charged. Furthermore, the control unit (400) continues to allow all of the battery cells (100) to be charged when a first condition, in which the voltage of the cell with the maximum voltage is greater than or equal to a first reference voltage (V₁), has not been met. However, when the first condition is met, the control unit (400) carries out a first control which allows the voltage of the cell with the maximum voltage to drop.

Description

Charging control system, battery pack and charging method

The present invention relates to a charge control system, a battery pack, and a charging method.

Various charging / discharging methods and control circuits have been proposed to prevent overcharging and overdischarging of the battery.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-232559) describes the following battery pack charge balance circuit. The battery pack charging balance circuit includes a first balance control circuit, a second balance control circuit, and a protection circuit. The first balance control circuit and the second balance control circuit are connected in series between both charge / discharge terminals of the charge / discharge circuit. The first balance control circuit has control units connected in parallel corresponding to the plurality of battery units. The second balance control circuit has a first branch and a second branch connected in parallel. As a result, the battery unit that has reached the preset imbalance protection activation voltage is shunted, and the protection circuit can be prevented from starting the overcharge protection function early. Therefore, it is supposed that the charge to each battery unit can be balanced.

Further, Patent Document 2 (Japanese Patent Laid-Open No. 09-322417) describes the following discharge method. The voltage of each battery unit is compared with the discharge end voltage, and when the voltage of any battery unit becomes lower than the discharge end voltage, the discharge of all the battery units is stopped. At this time, the temperature of each of the plurality of battery units is detected. The discharge end voltage is calculated giving priority to the lowest temperature among the detected temperatures. When the voltage of the lowest temperature battery unit or any one of the battery units drops to the discharge end voltage, the discharge is stopped. As a result, overdischarge can be prevented and the remaining capacity can be prevented from being lost quickly.

JP 2009-232559 A JP 09-322417 A

The inventor has found that the following problems occur in a battery pack having a plurality of battery units connected in series. In a plurality of battery units connected in series, the amount of deterioration differs for each battery unit. The full charge capacity of each battery unit is not always equal. Among them, the battery unit with the smallest full charge capacity increases the charging voltage faster than the other battery units. For this reason, when charging the battery pack, when the battery unit with the smallest full charge capacity reaches the overcharge protection voltage, the process ends at this timing. In this case, the charging ends with the amount of charge of all the battery units being insufficient. Therefore, in order to obtain a sufficient charge amount as a whole battery pack, there is a possibility that the battery unit having the smallest full charge capacity has to be overcharged.

According to the present invention,
A measuring unit for measuring voltages of a plurality of battery units connected in series;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, a charge control system is provided that performs a first control to drop the voltage of the maximum voltage unit.

According to the present invention,
A measuring unit for measuring voltages of a plurality of battery units connected in series;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, there is provided a charge control system for performing bypass control for bypassing the maximum voltage unit as a bypass target unit and continuing the charging for the battery units other than the bypass target unit.

According to the present invention,
A plurality of battery units connected in series;
A measurement unit for measuring the voltage of the battery unit;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, a battery pack is provided that performs a first control to drop the voltage of the maximum voltage unit.

According to the present invention,
A plurality of battery units connected in series;
A measurement unit for measuring the voltage of the battery unit;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, a battery pack is provided that performs bypass control for bypassing the maximum voltage unit as a bypass target unit and continuing the charging for the battery units other than the bypass target unit.

According to the present invention,
A charging start step for measuring voltages of a plurality of battery units connected in series and starting charging the plurality of battery units;
A unit identification step for identifying a voltage maximum unit in which the voltage is maximum based on the measured voltage;
A first determination step of determining a first condition that the voltage of the voltage maximum unit is equal to or higher than a first reference voltage;
When the first condition is not satisfied, the charging is continued for all the battery units, and when the first condition is satisfied, the first control step of decreasing the voltage of the maximum voltage unit;
A charging method is provided.

According to the present invention,
A charging start step for measuring voltages of a plurality of battery units connected in series and starting charging the plurality of battery units;
A unit identification step for identifying a voltage maximum unit in which the voltage is maximum based on the measured voltage;
A first determination step of determining a first condition that the voltage of the voltage maximum unit is equal to or higher than a first reference voltage;
When the first condition is not satisfied, the charging is continued for all the battery units, and when the first condition is satisfied, the voltage maximum unit is bypassed as a bypass target unit, and other than the bypass target unit. A bypass control step for continuing the charging for the battery unit;
A charging method is provided.

According to the present invention, when the first condition that the voltage of the maximum voltage unit is equal to or higher than the first reference voltage is satisfied, the voltage of the maximum voltage unit is decreased. Thereby, the maximum voltage unit is not overcharged. Therefore, it is possible to prevent the plurality of battery units connected in series from being overcharged and to approach full charge.

According to the present invention, a plurality of battery units connected in series can be brought close to full charge without being overcharged.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

It is a circuit diagram which shows the structure of the battery pack which concerns on 1st Embodiment. It is an equivalent circuit schematic of the battery cell vicinity of the battery pack which concerns on 1st Embodiment. It is a flowchart which shows the charge method which concerns on 1st Embodiment. It is a flowchart which shows the charge method which concerns on 1st Embodiment. It is a figure for demonstrating the charging method which concerns on 1st Embodiment. It is a figure of the comparative example for demonstrating the effect of 1st Embodiment. It is a circuit diagram which shows the structure of the battery pack which concerns on 2nd Embodiment. It is an equivalent circuit schematic of the battery cell vicinity of the battery pack which concerns on 2nd Embodiment. It is a flowchart which shows the charge method which concerns on 2nd Embodiment. It is a flowchart which shows the charging method which concerns on 3rd Embodiment. It is an equivalent circuit schematic of the battery cell vicinity of the battery pack which concerns on 4th Embodiment. It is a flowchart which shows the charging method which concerns on 4th Embodiment. It is a figure for demonstrating the charging method which concerns on 4th Embodiment. It is a flowchart which shows the charging method which concerns on 5th Embodiment. It is a figure for demonstrating the charging method which concerns on 5th Embodiment. It is a figure for demonstrating the charging method which concerns on 6th Embodiment. It is a figure for demonstrating the charging method which concerns on 7th Embodiment. It is a flowchart which shows the charging method which concerns on 8th Embodiment. It is a figure for demonstrating the charging method which concerns on 8th Embodiment. It is a circuit diagram which shows the structure of the battery pack and control circuit which concern on 9th Embodiment. It is a circuit diagram which shows the structure of the battery pack and control circuit which concern on 10th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

As used herein, “battery pack 10” refers to an assembled battery having a plurality of battery units. Further, the “battery unit” refers to one having at least one battery cell 100. Furthermore, the battery cell 100 included in the “battery unit” may include a plurality of single cells having a positive electrode and a negative electrode. Further, the plurality of “battery units” may have different numbers of battery cells 100. Hereinafter, a case where the “battery unit” included in the “battery pack 10” is a battery cell 100 having two unit cells connected in parallel will be described.

(First embodiment)
The battery pack 10 according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a circuit diagram showing a configuration of the battery pack 10 according to the first embodiment. FIG. 2 is an equivalent circuit diagram in the vicinity of the battery cell 100 of the battery pack 10 according to the first embodiment. The battery pack 10 includes a plurality of battery cells 100, a measurement unit 300, and a control unit 400. The plurality of battery cells 100 are connected in series. The measurement unit 300 measures the voltage of the battery cell 100. The control unit 400 controls charging of each battery cell 100 based on the voltage measured by the measurement unit 300. In addition, when charging the battery cell 100, the control unit 400 specifies the voltage maximum cell having the maximum voltage based on the voltage measured by the measurement unit 300. The control unit 400, when not satisfy the first condition to the voltage of the voltage maximum cell reached the first reference voltages V ₁ or more, to continue the charging to all of the battery cells 100. On the other hand, when the first condition is satisfied, the control unit 400 performs the first control to drop the voltage of the maximum voltage cell. Details will be described below.

As shown in FIG. 1, the battery pack 10 includes a plurality of battery cells 100. Here, the battery pack 10 includes, for example, N battery cells 100. The plurality of battery cells 100 are connected in series. Further, as described above, the battery cell 100 has two single cells. Specifically, the battery cell 100 is a Li ion secondary battery.

The battery pack 10 is deteriorated by repeated charging and discharging. In the process of this deterioration, each battery cell 100 does not necessarily deteriorate uniformly. The most deteriorated battery cell 100 has a reduced full charge capacity compared to the other battery cells 100. Therefore, when the battery pack 10 is charged, the most deteriorated battery cell 100 has a faster voltage increase during charging than the other battery cells 100. The “full charge capacity” here is a capacity (unit Ah) when the battery cell 100 is fully charged.

The battery pack 10 in the first embodiment has a control circuit 20 in addition to the battery cell 100. The control circuit 20 includes a measurement unit 300, a control unit 400, and a switch 500.

The control circuit 20 is connected to the battery cells 100 connected in series. The control circuit 20 has an internal positive terminal 620, an internal negative terminal 640, an external positive terminal 720, and an external negative terminal 740. The internal positive terminal 620 is connected to the positive electrode of one battery cell 100 connected in series. The internal negative terminal 640 is connected to the negative electrode of the other battery cell 100 connected in series.

The internal positive terminal 620 is connected to an external positive terminal 720 for connecting to an external device using the battery pack 10 via a wiring (not shown) in the control circuit 20. Similarly, the internal negative terminal 640 is connected to the external negative terminal 740. The internal negative terminal 640 and the external negative terminal 740 are grounded to the ground (GND).

A switch 500 for stopping charging or discharging is provided between the internal positive terminal 620 and the external positive terminal 720. For example, the switch 500 is provided between the internal positive terminal 620 and the external positive terminal 720 on the battery cell 100 side. In this case, the switch 500 is a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor), for example. In the switch 500, two P-channel MOSFETs are provided. Thereby, one MOSFET is used to control charging. On the other hand, the other MOSFET is used to control the discharge. Each MOSFET in the switch 500 is connected to the measurement unit 300.

If the switch 500 is an N-channel MOSFET, the switch 500 is disposed between the internal negative terminal 640 and the external negative terminal 740. In addition, the switch 500 may be, for example, an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), a relay, or a breaker.

Measurement unit 300 measures the voltage and current of each of the plurality of battery cells 100. The measurement unit 300 is connected to the battery cell 100 via the control unit 400.

Moreover, the control part 400 is provided in the battery cell 100 side rather than the measurement part 300, for example. The control unit 400 is connected to each battery cell 100 in order to adjust the charge amount of each battery cell 100.

The control unit 400 is connected to the measurement unit 300. The control unit 400 controls charging of each battery cell 100 based on the voltage measured by the measurement unit 300. The control unit 400 includes a calculation unit (not shown) that performs calculation processing based on the voltage or current measured by the measurement unit 300. The control unit 400 includes a communication unit (not shown) for transmitting a signal from the control unit 400 to an external device (not shown) or receiving a signal from the external device. An external communication terminal 760 for transmitting / receiving signals to / from an external device is connected to the control unit 400.

In addition, the measurement unit 300, the control unit 400, and the switch 500 function as a protection circuit in order to improve safety and charge / discharge cycle life. Measuring unit 300, the control unit 400 and the switch 500, the battery cell 100, when a voltage exceeding the overcharge protection voltage _{V OP} to be described later are charged, forcibly terminate charging. In addition, the control unit 400 includes a storage unit (not shown) that stores a first reference voltage V _{1 and the} like described later.

Thus, in the first embodiment, the battery pack 100 is packaged including the plurality of battery cells 100 and the control circuit 20.

Here, an equivalent circuit near the battery cell 100 will be described with reference to FIG. FIG. 2 shows an equivalent circuit of a part of the control unit 400 that controls charging of the battery cell 100. The dotted line in the figure indicates the inside of the control unit 400. Note that wirings for transmitting control signals and the like are omitted.

As shown in FIG. 2, the control unit 400 is connected to each battery cell 100 through wiring (not shown). In the control unit 400, an internal resistance 202 and a first cell switch 204 are arranged in parallel with each battery cell 100. When the first condition that the voltage (V _a ) of the maximum voltage cell is equal to or higher than the first reference voltage (V ₁ ) is satisfied, the control unit 400 sets the first cell switch 204 arranged in parallel with the maximum voltage cell. Turn on. As a result, the control unit 400 drops the voltage of the maximum voltage cell. Details of the operation of the control unit 400 related to charging will be described later.

Next, a method for charging the battery pack 10 will be described with reference to FIGS. 3 and 4 are flowcharts for explaining the charging method according to the first embodiment. FIG. 4 is a modification of FIG. FIG. 5 is a diagram for explaining the charging method according to the first embodiment. The charging method according to the first embodiment includes the following steps. First, while the measurement part 300 measures the voltage of the some battery cell 100 connected in series, the control part 400 starts charge to the some battery cell 100 (S110). Next, the control unit 400 specifies the voltage maximum cell having the maximum voltage based on the voltage measured by the measurement unit 300 (S120). Then, the control unit 400 determines a first condition to the voltage of the voltage maximum cell becomes the first reference voltages _{V 1} or (S130). Next, when the first condition is not satisfied (No in S130), the control unit 400 continues charging all the battery cells 100. On the other hand, when the first condition is satisfied (S130 Yes), the control unit 400 drops the voltage of the maximum voltage cell (first control step, S160). Details will be described below.

First, the external positive electrode terminal 720 and the external negative electrode terminal 740 are connected to the positive electrode and the negative electrode of an external charging device (not shown) that is a power supply destination. Thereby, charge of the some battery cell 100 is started. This charging is performed with a constant voltage and a constant current. Here, for example, the charging voltage is set to NV ₁ so that the voltage of the battery cell 100 becomes the first reference voltage V ₁ . The charging current is _IRS . The “charging voltage” here refers to a voltage during charging applied between an external positive terminal 720 and an external negative terminal 740 from an external charging device (not shown). The “charging current” refers to a current during charging applied between an external positive terminal 720 and an external negative terminal 740 from an external charging device (not shown). Here, it is assumed that the switch 500 has no internal resistance. At the same time, the measurement unit 300 measures the voltages of the plurality of battery cells 100 connected in series (S110). The measuring unit 300 also measures the current of the battery cell 100.

Next, the control unit 400 specifies the maximum voltage cell having the maximum voltage based on the voltage measured by the measurement unit 300 (S120). At this time, the control unit 400 also specifies the minimum voltage cell having the minimum voltage. Note that the maximum voltage cell and the minimum voltage cell may be switched during measurement.

Here, FIG. 5A shows the relationship between the time and the voltage of the battery cell 100 in the first embodiment. As shown in FIG. 5A, the voltage of the maximum voltage cell is indicated by Va and is indicated by _a thick solid line. The voltage of the minimum voltage cell is indicated by a thin solid line as _Vb .

At this time, the battery cells 100 including the maximum voltage cell and the minimum voltage cell are connected in series. For this reason, all the electric currents which flow through each battery cell 100 are equal. Therefore, among the plurality of battery cells 100, because the voltage maximum cell smaller full charge capacity C _Ra, increase in the voltage V _a is higher than the voltage V _b of the voltage minimum cell. In the first embodiment, since two unit cells are connected in parallel in the battery cell 100, a large current flows through the unit cell having the smaller deterioration.

FIG. 5B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the first embodiment. As shown in FIG. 5 (b), indicated by thick solid lines the remaining capacity of the voltage maximum cell as C _a. Further, the remaining capacity of the voltage minimum cell as C _b, are shown by a thin solid line. As shown in FIG. 5 (b), the charge until the time t ₁ is a constant-current charging. Therefore, the charging current of all the battery cells 100 _is constant _{I RS.} Therefore, the remaining capacity of each battery cell 100 increases linearly.

Then, the control unit 400 determines a first condition to the voltage of the voltage maximum cell becomes the first reference voltages _{V 1} or (S130). This “first reference voltage V ₁ ” is stored in the storage unit of the control unit 400. Here, the “first reference voltage V ₁ ” is a reference value of a voltage set lower than the overcharge protection voltage V _OP . Specifically, the “first reference voltage V ₁ ” is, for example, a rated charging voltage. Thereby, since the maximum voltage cell is not overcharged, deterioration of the maximum voltage cell can be suppressed. Note that the “rated charge voltage” is a chargeable voltage set lower than the overcharge protection voltage in consideration of safety when charging the battery pack 10.

Incidentally, the "first reference voltages V _1", as will be described later, because the reference voltage for determining whether to perform a first control for lowering the voltage V _a of the voltage maximum cell necessarily desired rated charge voltage Need not be the same value. That is, the “first reference voltage V ₁ ” may be equal to or higher than the rated charge voltage and lower than the overcharge protection voltage V _OP .

Here, the “overcharge protection voltage V _OP ” is an upper limit value of a voltage for preventing defects such as smoke generation, ignition or explosion in a lithium ion secondary battery, for example. When the battery cell 100 which is a lithium ion secondary battery is overcharged, dendritic (dendritic) lithium is generated, and the positive electrode and the negative electrode are short-circuited. In this case, there is a risk that heat is generated due to a short circuit and the battery pack 10 is ruptured. For this reason, “overcharge protection voltage V _OP ” is set as the maximum value of the charging voltage. When the maximum voltage cell becomes “overcharge protection voltage V _OP ”, the charging of the battery pack 10 is forcibly terminated. Specifically, the control unit 400 transmits a signal for stopping charging to the switch 500 via the measurement unit 300. Thereby, the maximum voltage cell is controlled so as not to be overcharged. In the present embodiment, the “overcharge protection voltage V _OP ” is stored in the storage unit of the control unit 400.

Then, the control unit 400, the voltage _{V a} of the voltage maximum cell a first lower than the reference voltage _{V 1,} when not satisfy the first condition (S130No), to continue the charging with respect to all the battery cells 100.

On the other hand, the voltage _{V a} of the voltage maximum cell becomes the first reference voltages _{V 1} or more, when the first condition is satisfied (S130Yes), the control unit 400, the voltage difference between the voltage maximum cell voltage minimum cell exceeds a predetermined value The second condition is determined to be less than (S140). The “predetermined voltage” here is determined based on the allowable range of the voltage difference between the maximum voltage cell and the minimum voltage cell, the measurement accuracy of the measurement unit 300, the allowable charge time, or the like. Specifically, the “predetermined voltage” is a limit value of the measurement accuracy of the measurement unit 300, for example.

Here, in FIGS. 5 (a) and 5 (b), when the first condition is satisfied (S130Yes) is at time _{t 1.} As shown in FIG. 5 (a), the voltage _{V a} of the voltage maximum cell has a first reference voltage _{V 1.} Therefore, the voltage V _a of the voltage maximum cell, a state that meets the first condition. Further, since the voltage difference between the maximum voltage cell and the minimum voltage cell is large, the second condition is not satisfied.

At this time, as shown in FIG. 5B, the remaining capacity C _a of the maximum voltage cell does not reach the full charge capacity C _Ra . Further, the remaining capacity C _b of the voltage minimum cell also not reached the full-charge capacity C _Rb. That is, all the battery cells 100 are not yet fully charged.

As described above, when the first condition is satisfied and the second condition is not satisfied (No in S140), the control unit 400 temporarily stops charging (S150) and drops the voltage of the maximum voltage cell as follows. (First control step, S160). Here, control in which the control unit 400 drops the voltage of the maximum voltage cell is referred to as “first control”.

First, the control unit 400 transmits a signal for stopping charging to the switch 500 via the measurement unit 300. Thereby, charging to all the battery cells 100 is temporarily stopped (S150). Here, the measurement unit 300 is connected to each battery cell 100 via the control unit 400. In such a battery pack 10, when the control unit 400 is operated while charging is continued, the measurement unit 300 cannot accurately measure the voltage of the battery cell 100 during that time. For this reason, when the voltage of each battery cell 100 approaches overcharge, the timing which detects that the battery cell 100 will be in an overcharge state becomes late, and it is dangerous. Therefore, the control unit 400 can safely control the charging of the battery cell 100 by temporarily stopping the charging of the battery cell 100 before the first control step (S160).

Next, the control unit 400 performs the first control to drop the voltage of the maximum voltage cell (S160).

Here, in FIGS. 5 (a) and 5 (b), the first control step (S160) is from time _{t 1} to time _{t 2.} As shown in FIG. 5A, from time t ₁ to time t ₂ , the voltage maximum cell consumes power by the internal resistance 202 of the control unit 400 described above. Thus, the voltage V _a of the voltage maximum cell drops. On the other hand, while the control unit 400 performs the first control, the control unit 400 keeps the first cell switch 204 arranged in parallel with the other battery cells 100 other than the maximum voltage cell open. That is, during this time, other battery cells 100 such as the minimum voltage cell are not loaded and are not charged as described above. For this reason, the voltage drop of the other battery cell 100 is only a voltage drop due to its own internal resistance (of the battery cell 100) or a minute voltage drop such as self-discharge. Therefore, the voltage drop of the above-described maximum voltage cell is larger than the voltage drop of the other battery cells 100. As a result, the voltage V _{a of the} maximum voltage cell and the voltage V _{b of the} minimum voltage cell can be gradually brought closer to each other. Note that as in FIG. 5 (b), at time _{t 2} from time _{t 1,} for example, the residual capacity _{C b} of the voltage minimum cell remains constant. Moreover, since all the battery cells 100 are not charged, the current is zero.

As shown in FIG. 3, in the first control step (S160), the control unit 400, for example, determines whether the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} (S170). Alternatively, as shown in FIG. 4, in the first control step (S160), the control unit 400 determines whether the time during which the first control is performed is equal to or longer than the first reference time (S172). Or the control part 400 may determine these two conditions simultaneously. By determining any of the above conditions, the control unit 400 can stop the first control as described later. In the first embodiment, the case of FIG. 3 is assumed. Incidentally, a large internal resistance 202 of the control unit 400, when a voltage drop V _a voltage maximum cell is slow, it is preferable to apply the conditions of FIG.

When the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} (S170Yes), the control unit 400, via the measurement unit 300, it transmits a signal for resuming the charging to the switch 500. At the same time, the control unit 400 stops the first control and restarts the charging of the battery cell 100 (S180).

Here, in FIGS. 5 (a) and 5 (b), the voltage _{V a} of the voltage maximum cell when a second reference voltage _{V 2,} is at time _{t 2.} In addition, the state has resumed charging is when from time t ₂ of time t _3. As in FIG. 5 (a), the voltage V _b of the voltage V _a and the voltage minimum cell voltage maximum cell, together rise again. Further, as shown in FIG. 5 (b), the residual capacity C _b of the voltage minimum cell rises again. In addition, the current of the minimum voltage cell is the charging current _IRS .

Thus, when a voltage V _a of the voltage maximum cell setting the conditions such as whether a second reference voltage V _2, the control unit 400 terminates the first control step (S160), and resumes charging be able to.

The condition for terminating the first control step (S160) is not limited to the above, and the same condition as the second condition that the voltage difference between the maximum voltage cell and the minimum voltage cell is less than a predetermined voltage is applied. You can also The condition for ending the first control step (S160) can be appropriately adjusted in consideration of the load on the control unit 400 and the like.

After the control unit 400 stops the first control (after S180), S120 to S170 are repeatedly performed. As shown in FIG. 5 (a), in a time _{t 8} from the time _{t 2, the} voltage _{V a} of the voltage maximum cell repeats rise due to the charging, the drop in the first control step (S160). On the other hand, the voltage _{V b} of the voltage minimum cell repeats rising voltage retention in the first control step (S160) by the charging. Thus, the voltage V _b of the voltage V _a and the voltage minimum cell voltage maximum cell can be gradually brought close. Further, as in FIG. 5 (b), it is possible to bring the residual capacity C _b of the voltage minimum cell gradually fully charged capacity C _Rb.

Incidentally, while repeating the steps from S120 ~ S170, when a voltage V _a of the voltage maximum cell drops, the voltage maximum cell may be replaced with other battery cells 100. In that case, the control unit 400, a voltage of a new voltage maximum cell as V _a, will determine the first condition and the like.

By setting the second condition in this way, the charging and the first control step (S160) are repeated until the voltage difference between the maximum voltage cell and the minimum voltage cell becomes less than a predetermined voltage. Therefore, the second condition that “the voltage difference between the maximum voltage cell and the minimum voltage cell is less than the predetermined voltage” here is an end condition when charging is repeated.

Then, FIG. 5 (a), the description will be given state at time _{t 8} in FIG. 5 (b). FIG. 5 (a), the state at the time _{t 8} in FIG. 5 (b), the control unit 400 is a state (S180) that stops the first control. As described above, the control unit 400 stops the first control and restarts the charging of the battery cell 100.

As shown in FIG. 5 (b), the a state of the time t _9, all of the battery cells 100 in the battery pack 10 is close to full charge. For this reason, it becomes difficult to be charged with respect to each battery cell 100, and an electric current begins to fall. That is, from the time t _9, the charge is constant-voltage charging. As in FIG. 5 (a), from the time t _9, the voltage V _b of the voltage V _a and the voltage minimum cell voltage maximum cell gradually rises slowly.

In FIG. 5 (a), at time _{t 10,} for example, the voltage _{V a} of the voltage maximum cell is equal to the first reference voltage _{V 1.} The voltage difference between the maximum voltage cell and the minimum voltage cell is almost zero. Therefore, in order to satisfy the first condition and satisfy the second condition (S140 Yes), the control unit 400 transmits a signal for stopping the charging to the switch 500 via the measurement unit 300 and terminates the charging ( S190).

At this time, the control unit 400 does not transmit a signal to the switch 500, but the control unit 400 transmits a signal for stopping charging to an external charging device via the external communication terminal 760. Also good.

Further, the control unit 400 may not terminate charging immediately after satisfying the second condition, but may terminate the charging after a predetermined time of charging (constant voltage charging) has elapsed.

Incidentally, when the voltage V _b of the voltage minimum cell becomes the first reference voltages V ₁ or more, the control unit 400 may transmit a signal for switching the charge from the constant voltage to a constant current to an external charging device. That is, when the voltage V _b of the voltage minimum cell becomes the first reference voltages V ₁ or more, may be forcibly switched to a constant-current charging. Thereby, all the battery cells 100 can be fully charged without reliably overcharging.

As described above, charging of the battery pack 10 according to the first embodiment is controlled.

Next, the effect of the first embodiment will be described using FIG. 6 as a comparative example. FIG. 6 is a diagram of a comparative example for explaining the effect of the first embodiment.

FIG. 6 shows a case of a comparative example in which the control unit 400 is charged without performing the first control for lowering the voltage of the maximum voltage cell, unlike the first embodiment. FIG. 6A shows the relationship between the time and the voltage of the battery cell 100 in the comparative example. FIG. 6B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the comparative example. Note that time t in FIG. 6 is independent of time t in FIG. Hereinafter, each figure including the time t is assumed to be independent when the figure numbers are different.

As shown in FIG. 6 (a), in the comparative example, the voltage V _a of the voltage maximum cell monotonically increases from start of charging. Further, the voltage V _a of the voltage maximum cell rises above a fast voltage V _b of the voltage minimum cell.

In the comparative example, there is no first condition for the control unit 400 to perform the first control. Therefore, the voltage V _a of the voltage maximum cell, until the total voltage of the N cells 100 is equal to NV _1, even when the first reference voltages V ₁ or continues to rise.

Voltage V _a voltage maximum cell rises to more overcharge protection voltage V _OP. Thus, if the voltage V _a of the voltage maximum cell rises to the overcharge protection voltage V _OP, the control unit 400, via the measurement unit 300, transmits a signal for stopping the switch 500. As a result, the control unit 400 forcibly terminates charging. At this time, the voltage V _{b of the} minimum voltage cell does not reach the first reference voltage V ₁ (rated charge voltage). Therefore, charging ends with the voltage difference between the maximum voltage cell and the minimum voltage cell being large.

Further, as shown in FIG. 6B, the remaining capacity C _a of the maximum voltage cell does not reach the full charge capacity C _Ra . Residual capacity C _b of the voltage minimum cell also not reached the full-charge capacity C _Rb. That is, all the battery cells 100 end charging even though they are not yet fully charged.

From this state, when the charge again to charge the voltage minimum cell voltage V _a voltage maximum cell exceeds the overcharge protection voltage V _OP. In this case, the maximum voltage cell may be in a dangerous state. For this reason, no more charging can be performed.

Further, when the battery pack 10 is charged again after being discharged, the battery pack 10 as a whole may not be able to obtain a sufficient charge amount unless the maximum voltage cell is overcharged.

Further, as described above, the voltage maximum cell is the battery cell 100 that has been most deteriorated. In the comparative example, charging the voltage V _a of the voltage maximum cell until the overcharge protection voltage V _OP. For this reason, since the voltage maximum cell becomes a state close to overcharging, the voltage maximum cell further deteriorates. That is, the full charge capacity C _Ra of the maximum voltage cell is further reduced. When charging / discharging is repeated in such a state, charging ends faster than the above. As a result, the battery pack 10 as a whole may gradually reduce the full charge capacity that can be charged.

On the other hand, according to the first embodiment, when the first condition is satisfied that the voltage V _a of the voltage maximum cell reached the first reference voltages V ₁ or more, the control unit 400, a voltage V _a voltage maximum cell The first control for lowering is performed. Thereby, it is possible to prevent the maximum voltage cell from being overcharged. Further, it is possible to make the voltage V _a of the voltage maximum cell, the voltage of the other battery cells 100.

From this state, when the charge again to charge the voltage minimum cell, the voltage V _a of the voltage maximum cell are lowered, it is possible to further charge the entire battery pack 10. Further, as described above, the voltage V _{a of the} maximum voltage cell and the voltage V _{b of the} minimum voltage cell can be brought close to each other, whereby each battery cell 100 can be brought close to full charge.

Further, according to the first embodiment, when the voltage V _a of the voltage maximum cell reached the first reference voltages V ₁ or more, lowering the voltage V _a of the voltage maximum cell. Thus, the voltage V ₁ of the voltage maximum cell is high as the overcharge protection voltage V _OP, that is, the voltage up to an overcharged cell, it is not possible to terminate charging. Therefore, deterioration of the maximum voltage cell can be suppressed.

Further, according to the first embodiment, the circuit shown in FIG. 2 has a simple structure including only the internal resistor 202 and the first cell switch 204. Thereby, the control part 400 can be accommodated in the small area | region in the battery pack 10. FIG. In addition, the circuit of the control unit 400 is highly reliable and can be formed at low cost.

As described above, according to the first embodiment, the battery pack 10 having the plurality of battery cells 100 connected in series can be prevented from being overcharged, and can be close to full charge.

As described above, in the first embodiment, the case where the charging is restarted after determining the first condition has been described. However, the second condition is satisfied that the voltage difference between the voltage maximum cell and the voltage minimum cell is less than a predetermined voltage. Until then, the control unit 400 may continue to perform the first control.

In the first embodiment, the case where the charging is terminated using the second condition when the charging is repeatedly performed has been described. However, the charging that the user arbitrarily terminates the charging using only the first condition. It may be a control system or a charging method.

(Second Embodiment)
The battery pack 10 according to the second embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a circuit diagram showing a configuration of the battery pack 10 according to the second embodiment. FIG. 8 is an equivalent circuit diagram in the vicinity of the battery cell 100 of the battery pack 10 according to the second embodiment. The second embodiment is the same as the first embodiment except for the following points. The battery pack 10 of the second embodiment further includes a balance circuit 200 that adjusts the charge amount of each battery cell 100. In addition, the control unit 400 controls the operation of the balance circuit 200. Further, the control unit 400 performs the first control by operating the balance circuit 200 when the first condition is satisfied. Details will be described below.

As shown in FIG. 7, the battery pack 10 in the second embodiment includes a balance circuit 200 in addition to the configuration of the first embodiment. The balance circuit 200 adjusts the charge amount of each battery cell 100.

The measuring unit 300 is connected to the battery cell 100 via the balance circuit 200.

Further, the balance circuit 200 is provided closer to the battery cell 100 than the measurement unit 300. The balance circuit 200 is connected to each battery cell 100 in order to adjust the charge amount of each battery cell 100.

The control unit 400 is connected to the external positive electrode terminal 720 and the external negative electrode terminal 740 side of the measurement unit 300. The control unit 400 controls the operation of the balance circuit 200 based on the voltage measured by the measurement unit 300. The control unit 400 includes a calculation unit (not shown) that performs calculation processing based on the voltage or current measured by the measurement unit 300.

Thus, the battery pack 10 of the second embodiment is different from the control unit 400 in the balance circuit 200 that controls the charging of each battery cell 100 among the functions of the control unit 400 of the first embodiment. It is provided as a system.

Here, an equivalent circuit in the vicinity of the battery cell 100 will be described with reference to FIG. FIG. 8 shows an equivalent circuit of the balance circuit 200. A dotted line in the figure indicates the inside of the balance circuit 200.

As shown in FIG. 8, the balance circuit 200 is connected to each battery cell 100 via wiring (not shown). In the balance circuit 200, an internal resistor 202 and a first cell switch 204 are arranged in parallel with each battery cell 100. When the first condition that the voltage (V _a ) of the maximum voltage cell becomes equal to or higher than the first reference voltage (V ₁ ) is satisfied, the control unit 400 operates the balance circuit 200 in parallel with the maximum battery cell. 1st cell switch 204 arrange | positioned is turned ON. Thereby, the control part 400 can perform 1st control by the balance circuit 200. FIG.

Next, a method for charging the battery pack 10 according to the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart for explaining the charging method according to the first embodiment. The charging method of the second embodiment is the same as that of the first embodiment except that the first control is performed by operating the balance circuit 200. Details will be described below.

As shown in FIG. 9, the charging method of the second embodiment is the same as that of the first embodiment up to S150.

Here, when the first condition is satisfied and the second condition is not satisfied (No in S140), the control unit 400 temporarily stops charging (S150) and operates the balance circuit 200 (first) as follows. Control step, S160).

As shown in FIG. 9, it is determined in the first control step (S160), for example, whether the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} (S170). Alternatively, as shown in FIG. 4, in the first control step (S160), it may be determined whether or not the operation time of the balance circuit 200 has become equal to or longer than the first reference time after the operation of the balance circuit 200. Alternatively, these two conditions may be determined at the same time. Incidentally, a large internal resistance 202 of the balance circuit 200, when a voltage drop V _a voltage maximum cell is slow, it is preferable to apply the conditions of FIG.

When the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} (S170Yes), the control unit 400, via the measurement unit 300, it transmits a signal for resuming the charging to the switch 500. At the same time, the control unit 400 stops the balance circuit 200 (stops the first control) and restarts the charging of the battery cell 100 (S180).

The condition for terminating the first control step (S160) is not limited to the above, and the same condition as the second condition that the voltage difference between the maximum voltage cell and the minimum voltage cell is less than a predetermined voltage is applied. You can also The condition for ending the first control step (S160) can be appropriately adjusted in consideration of the load on the balance circuit 200 and the like.

After the control unit 400 stops the balance circuit 200 (after S180), S120 to S170 are repeatedly performed. The subsequent steps are the same as in the first embodiment.

As described above, charging of the battery pack 10 according to the second embodiment is controlled.

According to the second embodiment, the balance circuit 200 is provided as a system different from the control unit 400. Thereby, the control part 400 can perform 1st control by operating the balance circuit 200, when satisfy | filling 1st conditions. In addition, as described in the first embodiment, the balance circuit 200 can be formed with high reliability and low cost.

(Third embodiment)
FIG. 10 is a flowchart illustrating a charging method according to the third embodiment. The third embodiment is the same as the first embodiment or the second embodiment except that there are a plurality of conditions for terminating charging. Details will be described below.

Here, it is assumed that the third embodiment includes the balance circuit 200 as in the second embodiment.

First, as shown in FIG. 10, charging of the battery pack 10 having a plurality of battery cells 100 is started. At the same time, the measurement unit 300 measures the voltage and current of the plurality of battery cells 100 connected in series (S110).

Next, the control unit 400 identifies the maximum voltage cell and the minimum voltage cell based on the voltage measured by the measurement unit 300 (S120).

Next, the control unit 400 determines a fifth condition that the current of each battery cell 100 is equal to or less than the reference current (S210). Here, when charging is performed with a constant current, the current starts to drop when the charging approaches a full charge. The “reference current” here is a reference value of current for detecting a change in charging current. By providing the “reference current” in this way, it can be determined that the battery cell 100 is approaching full charge based on the current of each battery cell 100. Specifically, the “reference current” is, for example, a charging end current I ₀ . The “end current I ₀ ” here is a current that has converged to a certain value when the battery cell 100 approaches full charge. Therefore, it is possible to control so as to protect the overcharge of the battery cell 100 by determining not only the voltage but also the current.

The control unit 400 continues the charging when the fifth condition is not satisfied (S210 No). On the other hand, when the fifth condition is satisfied (S210 Yes), the control unit 400 ends the charging.

In addition, as long as the balance circuit 200 is not operating, the determination based on the fifth condition may be performed at any timing during charging.

Then, the control unit 400 determines a first condition to the voltage of the voltage maximum cell becomes the first reference voltages _{V 1} or (S130).

Controller 400, a voltage of the voltage maximum cell lower than the first reference voltage _{V 1,} when not satisfy the first condition (S130No), to continue the charging. On the other hand, the control unit 400, the voltage _{V a} of the voltage maximum cell becomes the first reference voltages _{V 1} or more, when the first condition is satisfied (S130Yes), further determines as follows.

The control unit 400 determines a second condition that satisfies the first condition and that the voltage difference between the maximum voltage cell and the minimum voltage cell is less than a predetermined value (S140).

When the first condition is satisfied and the second condition is satisfied (S140 Yes), the control unit 400 ends the charging. On the other hand, when the first condition is satisfied and the second condition is not satisfied (No in S140), the control unit 400 further performs the following determination.

Next, the control unit 400 determines a third condition that satisfies the first condition and that the integrated value of the number of operations of the balance circuit 200 during charging is equal to or greater than a predetermined value (S220). As a result, the balance circuit 200 can be prevented from continuing to operate indefinitely due to severe termination conditions. When there is no balance circuit 200 and only the control unit 400, the third condition is that the integrated value of the number of times of performing the first control is equal to or greater than a predetermined value.

The control unit 400 ends the charging when the first condition is satisfied and the third condition is satisfied (S220 Yes). On the other hand, when the first condition is satisfied and the third condition is not satisfied (No in S220), the control unit 400 further performs the following determination.

The control unit 400 determines a fourth condition that the charging time obtained by integrating the charging time has passed a second reference time longer than the first reference time (S230). Based on the determination result of the fourth condition, the control unit 400 controls the balance circuit 200, thereby preventing the charging time from becoming excessively long.

When the fourth condition is satisfied (S230 Yes), the control unit 400 ends the charging. On the other hand, when the first condition is satisfied and the third condition is not satisfied (No in S230), the control unit 400 transmits a signal for temporarily stopping charging to the switch 500 via the measurement unit 300, Charging is suspended (S150).

Next, the control unit 400 operates the balance circuit 200 (first control step, S160).

In a first control step (S160), the control unit 400, for example, determines whether the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} (S170). Alternatively, in the first control step (S160), the control unit 400 may determine whether the operation time of the balance circuit 200 has become equal to or longer than the first reference time after operating the balance circuit 200.

When the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2} or when the operating time of the balance circuit 200 becomes the first reference time or more (S160Yes), the control unit 400, the stop balancing circuit 200 And charging of the battery cell 100 is resumed (S180).

By repeatedly performing the above steps, it is possible to bring all the battery cells 100 close to full charge as in the first embodiment. In addition, the timing which complete | finishes charge should just be in the state which satisfy | fills any one of 2nd condition, 3rd condition, 4th condition, or 5th condition.

Next, the effect of the third embodiment will be described.

According to the third embodiment, the controller 400 is set with a plurality of charging termination conditions. Here, depending on the user, it is assumed that the minimum voltage cell is charged as much as possible and the battery pack 10 is desired to be used quickly. In such a case, it is preferable to terminate the charging at an early stage under an end condition that meets the user's needs, rather than setting a strict end condition that matches the charge amounts of all the battery cells 100. Therefore, by setting various desired termination conditions as in the third to fifth conditions in the third embodiment, it is possible to prevent an excessively long charging time.

As described above, in the third embodiment, the control system or the charging method according to the flowchart as shown in FIG. 6 has been described. However, the timing for determining from the second condition to the fourth condition is any timing after S140. You may go. The step of determining the fifth condition may be performed at any timing during charging.

In the third embodiment, the case where the balance circuit 200 is provided has been described. However, the control may be performed only by the control unit 400 as in the first embodiment. In this case, in the third embodiment, the same control can be performed by replacing the portion of “activate the balance circuit 200” with “perform first control”.

(Fourth embodiment)
A battery pack 10 according to the fourth embodiment will be described with reference to FIG. FIG. 11 is an equivalent circuit diagram in the vicinity of the battery cell 100 of the battery pack 10 according to the fourth embodiment. The fourth embodiment is the same as the first embodiment except for the following points. When the first condition is satisfied, the control unit 400 bypasses the maximum voltage cell as a bypass target unit, and continues charging the battery cell 100 of the bypass target unit. Details will be described below.

FIG. 11 shows an equivalent circuit of a part of the control unit 400 that controls charging of the battery cell 100. The dotted line in the figure indicates the inside of the control unit 400. Note that wirings for transmitting control signals and the like are omitted.

As shown in FIG. 11, the control unit 400 is connected to each battery cell 100 via wiring (not shown). Each battery cell 100 is connected to each other via a second cell switch 206. In the control unit 400, a third cell switch 208 is arranged in parallel with each battery cell 100 and the second cell switch 206. The second cell switch 206 and the third cell switch 208 may be individually turned on, but are controlled so as not to be turned on at the same time. Thereby, the control unit 400 prevents the battery cell 100 from being short-circuited between the positive and negative electrodes.

The control unit 400 turns on the second cell switch 206 and turns off the third cell switch 208 when discharging the normal battery pack 10 or the like. On the other hand, when the control unit 400 bypasses the battery cell 100, the control unit 400 turns off the second cell switch 206 connected to the battery cell 100, and the third cell switch arranged in parallel with the battery cell 100. Turn 208 on. Here, “the second cell switch 206 connected to the battery cell 100” refers to the second cell switch 206 connected to the negative electrode side of the battery cell 100.

Here, when the first condition that the voltage (V _a ) of the maximum voltage cell is equal to or higher than the first reference voltage (V ₁ ) is satisfied, the control unit 400 bypasses the maximum voltage cell as a “bypass target unit”. . At this time, as described above, the second cell switch 206 connected to the maximum voltage cell is turned OFF, and the third cell switch 208 arranged in parallel with the maximum battery cell is turned ON. Thereby, the control part 400 can bypass a voltage largest cell. Details of the operation of the control unit 400 related to charging will be described later.

Next, a method for charging the battery pack 10 according to the fourth embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a flowchart for explaining a charging method according to the fourth embodiment. In FIG. 12, step numbers are reassigned. FIG. 13 is a diagram for explaining a charging method according to the fourth embodiment. The charging method according to the fourth embodiment includes the following steps. First, the measurement unit 300 measures the voltage of the plurality of battery cells 100 connected in series, and the control unit 400 starts charging the plurality of battery cells 100 (S410). Next, the control unit 400 identifies the voltage maximum cell having the maximum voltage based on the voltage measured by the measurement unit 300 (S430). Then, the control unit 400 determines a first condition to the voltage of the voltage maximum cell becomes the first reference voltages _{V 1} or (S440). Next, when the first condition is not satisfied (No in S440), the control unit 400 continues charging all the battery cells 100. On the other hand, when the first condition is satisfied (S440 Yes), the control unit 400 bypasses the voltage maximum cell as a bypass target unit and continues charging the battery cells 100 other than the bypass target unit (bypass control step, S460). Details will be described below.

In the above embodiment, the control part 400 demonstrated the method of specifying one battery cell 100 with the largest voltage as a "voltage largest cell", and controlling a voltage. On the other hand, in the fourth embodiment, when the current “maximum voltage cell” satisfies the first condition, the control unit 400 collectively performs a bypass control as a “bypass target unit”. As used herein, the “bypass target unit” refers to a set of one or more battery cells 100 that are bypassed by bypass control.

In the fourth embodiment, the battery cell 100 whose voltage reaches the first reference voltage V ₁ the earliest is the “first cell”, the battery cell 100 that reaches the next is the “second cell”, and all the battery cells. The battery cell 100 that reaches the latest among the 100 is defined as a “third cell”.

Here, the charging current is _IRS as the initial charging state.

First, as shown in FIG. 12, as in the first embodiment, charging is started, and the measurement unit 300 measures the voltage and current of the battery cell 100 (S410).

Next, the control unit 400 identifies the “minimum voltage cell” based on the voltage measured by the measurement unit 300 (S420). A battery cell 100 that is a “minimum voltage cell” is specified from battery cells 100 other than “bypass target cells” described later.

Next, the control unit 400 identifies the “maximum voltage cell” based on the voltage measured by the measurement unit 300 (S430). At this stage, it is assumed that the “first cell” has the highest voltage and the “voltage maximum cell”.

Here, FIG. 13A shows the relationship between the time and the voltage of the battery cell 100 in the fourth embodiment. Figure 13 (a), the indicated by a thick line a voltage of the first cell as V _a, the voltage of the second cell indicated by the thick dotted line as V _C, are shown by a thin line a voltage of the third cell as V _b.

FIG. 13B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the fourth embodiment. In FIG. 13B, the remaining capacity of the first cell is shown as a thick line as C _a , the remaining capacity of the second cell is shown as a thick dotted line as C _c , and the remaining capacity of the third cell is shown as a thin line as C _b. Yes.

As shown in FIG. 13 (a), the at up to time _{t 1, the} increase in the voltage _{V a} of the first cell is the earliest. That is, the maximum voltage cell is the first cell. Increase in the voltage V _c of the second cell is also faster than the voltage V _b of the third cell. Voltage _{V a} of the first cell is first less than the reference voltage _{V 1,} when not satisfy the first condition (S440No), the control unit 400 continues the charge for all the battery cells 100. Note that as in FIG. 13 (b), until the time t _1, the remaining capacity of all of the battery cells 100, rises linearly.

At time _{t 1,} the voltage _{V a} of the first cell is a voltage maximum cell, a first reference voltages _{V 1,} and the first condition is satisfied (S440Yes).

When the voltage maximum cell satisfies the first condition (S440 Yes), the control unit 400 includes the first cell that is the current maximum battery cell in the “bypass target unit” (S460). At time t _1, the bypass target unit is only one of the first cell.

Next, the control unit 400 bypasses the above-described maximum voltage cell as a bypass target unit, and performs bypass control to continue charging the battery cells 100 other than the bypass target unit (bypass control step, S460).

At this time, as described above, the control unit 400 turns off the second cell switch 206 connected to the first cell which is the maximum voltage cell, and the third cell arranged in parallel with the first cell. Switch 208 is turned on. Thereby, the control part 400 bypasses the 1st cell which is a voltage largest cell.

At this time, the external charging device continues constant current charging. Even bypassing target unit bypassed allowed time t ₁ after the charging current does not change in I _RS. Therefore, the battery cells 100 other than the maximum voltage cell are continuously charged with the same voltage as before the bypass target unit was bypassed.

Moreover, the control part 400 transmits the signal which shows the number of the battery cells 100 bypassed as a bypass object unit to an external charging device by bypass control. At this time, the control unit 400 transmits a signal that the battery cell 100 is one of the first cells. Thereby, the voltage is not fluctuating due to the abnormality on the battery pack 10 side, but the fact that the voltage is fluctuating by the bypass control on the battery pack 10 side can be transmitted to the external charging device.

Further, the control unit 400 may transmit a signal for lowering the charging voltage applied by charging by the voltage of the bypass target unit to the external charging device. Thereby, the said signal can be made into the alternative signal of the signal which shows the number of the battery cells 100 bypassed as a bypass object unit. At time t _1, since the bypass unit under only the first cell, the control unit 400 transmits a signal for lowering by V _1.

As shown in FIG. 13A, since the first cell is bypassed from time t ₁ to time t ₂ , the voltage V _a of the first cell is the open circuit voltage v excluding the loss component due to the internal resistance. Drop to _1a to maintain a constant voltage. Here, the “open voltage” refers to a voltage when the positive electrode and the negative electrode of the battery cell 100 are opened. The battery cell 100 has an internal resistance. For this reason, the voltage applied to the battery cell 100 during charging is superimposed with the voltage of the loss component due to the internal resistance. Therefore, when the battery cell 100 is bypassed (opened) as described above, the voltage of the battery cell 100 drops to the open voltage excluding the loss component due to the internal resistance.

On the other hand, during the period from time t ₁ to time t _2, the voltage of the battery cell 100 other than the bypass target unit by the constant current charging, increases monotonously.

As shown in FIG. 13 (b), the time t ₁ after, since the first cell is bypassed, the remaining capacity C _a first cell is a bypass target unit maintains a constant value. On the other hand, during the period from time t ₁ to time t _2, the remaining capacity of the battery cell 100 other than the bypass target unit by the constant current charging, increases linearly.

Then, the control unit 400 determines whether the voltage _{V b} of the third cell is the voltage minimum cell becomes the first reference voltages _{V 1} or (S470). Between the time _{t 1} to time _{t 2} is still, the voltage _{V b} of the third cell is the voltage minimum cell not the first reference voltages _{V 1} or (S470No), the control unit 400 continues to charge Let

Here, returning to S420, the “voltage minimum cell” having the minimum voltage is specified from among the battery cells 100 other than the bypass target unit (S420). Depending on the magnitude of the open circuit voltage, the battery cell 100 included in the bypass target unit may be the battery cell 100 having the lowest voltage. For this reason, in the identification, the control unit 400 excludes the bypass target unit from the search target. Here, the third cell is the “minimum voltage cell”.

The control unit 400 again identifies the current “maximum voltage cell” (S430). The current “maximum voltage cell” in which the voltage is maximum between time t ₁ and time t ₂ is the second cell. Therefore, the control unit 400 updates the second cell as a new “maximum voltage cell”. In this way, the control unit 400 updates a new voltage maximum cell whose voltage is currently maximum at any time.

Then, when the time _{t 2, the} second cell was a new voltage maximum cell, a first reference voltages _{V 1,} and the first condition is satisfied (S440Yes).

When the second cell that has become the new maximum voltage cell satisfies the first condition (S440 Yes), the control unit 400 includes the second cell that is the current maximum voltage cell in the bypass target unit (S450). Here, “include in the bypass target unit” means that the control unit 400 collectively controls the bypass target unit.

Next, the control unit 400 performs bypass control that bypasses the bypass target unit including the second cell and continues charging the battery cells 100 other than the bypass target unit (bypass control step, S460). That is, the control unit 400 bypasses not only the first cell but also the second cell.

At this time, the external charging device continues constant current charging. Even newly time t ₂ after which bypass the second cell as a bypass target unit, the charging current does not change in I _RS. Therefore, the battery cells 100 other than the bypass target unit are continuously charged at the same voltage as before the second cell was newly bypassed.

Moreover, the control part 400 transmits the signal which shows the number of the battery cells 100 bypassed as a bypass object unit to an external charging apparatus by bypass control. Specifically, when the time t _2, the number of battery cells 100 are bypassed by the bypass control is "two" in the first cell and the second cell. At this time, the control unit 400 transmits a signal indicating “two”, which is the number of the bypassed battery cells 100, to the external charging device. Thereby, it can be transmitted to the external charging device that the voltage is fluctuating due to the fluctuating number of bypassed battery cells 100 on the battery pack 10 side.

Furthermore, the control unit 400 may transmit a signal for lowering the charging voltage by the voltage of the bypass target unit including the second cell to the external charging device. When time t _2, the bypass object unit is became two and, control unit 400 transmits a signal for lowering the charge voltage by 2V _1.

As shown in FIG. 13A, the voltage Va of the first cell is constant at the open circuit voltage v _1a from time t ₂ to time t ₃ . In addition, since the second cell that is the bypass target unit is bypassed, the voltage V _c of the second cell drops to the open voltage v _1c excluding the loss component due to the internal resistance, and maintains a constant voltage. Here, the first cell whose voltage rise was the fastest is more deteriorated than the second cell. For this reason, the internal resistance of the first cell is larger than the internal resistance of the second cell. Accordingly, the open voltage v _1c of the second cell is greater than the open voltage v _1a of the first cell. On the other hand, during the period from time t ₂ to time t _3, the voltage of the battery cell 100 other than the bypass target unit by the constant current charging, increases monotonously.

As shown in FIG. 13 (b), the time t ₂ later, since the second cell is bypassed, the remaining capacity C _c of the second cell maintains a constant value. On the other hand, during the period from time t ₂ to time t _3, the remaining capacity of the battery cell 100 other than the bypass target unit by the constant current charging, increases linearly.

Then, the control unit 400 judges again whether the voltage _{V b} of the third cell is the voltage minimum cell becomes the first reference voltages _{V 1} or (S470). From time t ₂ to time t _3, since the voltage V _b of the third cell, which is the minimum voltage cell, is not equal to or higher than the first reference voltage V ₁ (S470 No), the control unit 400 continues to charge. Let

Here, the process returns to S420, and the control unit 400 identifies the “minimum voltage cell” having the minimum voltage from the battery cells 100 other than the bypass target unit (S420). Again, the third cell is the “minimum voltage cell”.

The control unit 400 again identifies the current “maximum voltage cell” (S430). The controller 400 updates the battery cell 100 whose voltage is currently maximum between time t ₂ and time t ₃ as a new “voltage maximum cell”. At this stage, the battery cell 100 not shown in FIG. 13 corresponds to the “maximum voltage cell”. In this way, the control unit 400 updates a new voltage maximum cell whose voltage is currently maximum at any time.

Here, S440 is performed, and the battery cells 100 other than the bypass target unit are charged until the battery cell 100 that has newly become the maximum voltage cell satisfies the first condition. Next, the control unit 400 repeats S430 to S460 until S470 is satisfied. Every time the new voltage maximum cell satisfies the first condition, the current voltage maximum cell is integrated as a bypass target unit to perform bypass control. Go.

At this time, as described above, the control unit 400 transmits a signal indicating the number of battery cells 100 bypassed as a bypass target unit to the external charging device by bypass control. When the number of bypass target units is k, control unit 400 transmits a signal indicating k to the external charging device. Thereby, it can be transmitted to the external charging device that the voltage is fluctuating due to the fluctuating number of bypassed battery cells 100 on the battery pack 10 side.

While repeating S430 to S460 until S470 is satisfied, the control unit 400 may transmit a signal for decreasing the voltage of the bypass target unit to the external charging device. When the number of bypass target units is k, the control unit 400 transmits a signal for reducing the charging voltage by kV ₁ .

Finally, all the battery cells 100 other than the minimum voltage cell are included in the bypass target unit.

At time _{t 3,} the voltage _{V b} of the third cell is a voltage minimum cell has a first reference voltages _{V 1} or (S470Yes)

When the voltage _{V b} of the third cell is a voltage minimum cell that is the first reference voltages _{V 1} or (S470Yes), the control unit 400 stops the bypass control. Thereby, charging is restarted for all the battery cells 100.

At this time, after stopping bypass control, control unit 400 transmits a signal for switching charging from a constant current to a constant voltage to an external charging device. This makes it possible to constant voltage charging at the first reference voltages V ₁ to all of the battery cells 100. Moreover, all the battery cells 100 are not overcharged.

As shown in FIG. 13 (a), the voltages of all the battery cells 100 is constant at the first reference voltage _{V 1.} Further, as shown in FIG. 13B, the charging current gradually decreases, and decreases to the termination current I ₀ at time t ₄ . Further, at time t _4, the remaining capacity of all of the battery cells 100 is charged to the full charge capacity. Here, the control unit 400 ends the charging (S490).

Here, the condition for the control unit 400 to end the charging can be the fifth condition in the third embodiment. That is, when the currents of all the battery cells 100 become equal to or lower than the reference current (for example, the termination current I ₀ ), the control unit 400 can end the charging. Further, the condition for the control unit 400 to end the charging can be the fourth condition in the third embodiment. That is, when the charging time obtained by integrating the charging time during the charging has passed the second reference time, the control unit 400 can end the charging.

According to the fourth embodiment, when the first condition is satisfied, the control unit 400 bypasses the maximum voltage cell as a bypass target unit and continues charging the battery cells other than the bypass target unit. I do. Thereby, the maximum voltage cell is not overcharged. In addition, while the bypass target unit is bypassed, all the battery cells 100 can be brought close to full charge quickly by continuing charging the battery cells 100 other than the bypass target unit.

(Fifth embodiment)
A battery pack 10 according to the fifth embodiment will be described with reference to FIGS. 14 and 15. FIG. 14 is a flowchart for explaining a charging method according to the fifth embodiment. FIG. 15 is a diagram for explaining a charging method according to the fifth embodiment. The fifth embodiment is the same as the fourth embodiment except that the steps after S470 Yes are different. Details will be described below.

The configuration of the battery pack 10 of the fifth embodiment is the same as that of the fourth embodiment. Names such as “first cell” are the same as those in the fourth embodiment.

Suppose that the battery pack 10 is charged according to FIG. Similarly to the fourth embodiment, the control unit 400 repeats S430 to S460 until S470 is satisfied, and every time the current new maximum voltage cell satisfies the first condition, the current maximum voltage cell is bypassed. As a whole, bypass control is performed.

Here, FIG. 15A shows the relationship between the time and the voltage of the battery cell 100 in the fifth embodiment. In FIG. 15, as in FIG. 13, the first cell is indicated by a bold line. The second cell and the third cell are the same as in FIG.

FIG. 15B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the fifth embodiment.

Now, it is to be a time _{t 3.} At time _{t 3,} the voltage _{V b} of the third cell is a voltage minimum cell has a first reference voltages _{V 1} or (S470Yes).

When the voltage _{V b} of the third cell is a voltage minimum cell that is the first reference voltages _{V 1} or (S470Yes), the control unit 400, all of the battery cells 100, a predetermined time, bypassing (S475). Thus, the third voltage V _b is the voltage minimum cell drops to the open-circuit voltage v _1b. Since the internal resistance of the third cell, which is the minimum voltage cell, is the lowest as compared to other battery cells 100, the open voltage _v1b of the third cell, which is the minimum voltage cell, is the open voltage of the other battery cell 100. Bigger than.

The control for bypassing all the battery cells 100 here is performed by the control unit 400, for example. In other words, the control unit 400 performs bypass control using the third cell as a bypass target unit. Alternatively, the control unit 400 may turn off the switch 500.

Further, the “predetermined time” from time t ₃ to time t ₄ here means time for switching from constant current charging to constant voltage charging. Specifically, it may be longer than the time required for the external charging device to switch the charging.

When a predetermined time has elapsed time _{t 4,} the control unit 400 resumes the charging (S480). At this time, when all the battery cells 100 are bypassed as bypass control, the control unit 400 stops the bypass control. On the other hand, when the switch 500 is turned off, the control unit 400 turns on the switch 500 again.

Further, at time t ₄ when a predetermined time has elapsed, the control unit 400, after stopping the bypass control, and transmits a signal for switching the charge from constant current to constant voltage to the external charging device. This makes it possible to constant voltage charging at the first reference voltages V ₁ to all of the battery cells 100.

The subsequent steps are the same as those in the fourth embodiment.

According to the fifth embodiment, when the voltage V _b of the third cell is the voltage minimum cell has a first reference voltages V ₁ or more, the control unit 400, all of the battery cells 100, a predetermined time, Bypass. Thereby, when switching charging from a constant current to a constant voltage, the charging can be stably switched.

As described above, in the fifth embodiment, the case where the control is performed only by the control unit 400 has been described. However, the balance circuit 200 may be provided as in the second embodiment. In this case, when the first condition is not satisfied, the control unit 400 continues to charge all the battery cells 100, and performs the bypass control by operating the balance circuit 200 when the first condition is satisfied.

(Sixth embodiment)
FIG. 16 is a diagram for explaining a charging method according to the sixth embodiment. The sixth embodiment is the same as the first embodiment or the second embodiment except that the battery cell 100 is recycled. Details will be described below.

The battery cell 100 according to the sixth embodiment is recycled by collecting the used battery cell 100 and reassembling it. Here, “recycling” means that the manufacturer collects the used battery pack 10 and then disassembles the battery pack 10 to reuse the used battery cell 100. The “used battery pack 10” refers to a battery pack 10 that has been charged or discharged at least once. Therefore, the battery pack 10 is an assembled battery of recycled battery cells 100. As described above, when the battery cell 100 is recycled, the battery cell 100 has a different use time for each battery pack 10 that has been used, and thus the degree of deterioration is also different. For this reason, the situation where the speed at which the voltage rises differs depending on the battery cell 100 can be considered.

Here, FIG. 16A shows the relationship between the time and the voltage of the battery cell 100 in the sixth embodiment. As shown in FIG. 16 (a), the show the most degraded voltage of the battery cell 100 by the thick solid line as V _a. Further, the voltage of the battery cell 100 that is least deteriorated is indicated by a thin solid line as _Vb .

FIG. 16B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the sixth embodiment. As shown in FIG. 16 (b), the are indicated by thick solid lines the most degraded remaining capacity of the battery cell 100 as a C _a. Further, the remaining capacity of the battery cell 100 that is not degraded most as C _b, are shown by a thin solid line.

Here, as shown in FIG. 16B, a case is considered where the remaining capacity of the most deteriorated battery cell 100 is smaller than that of the least deteriorated battery cell 100 in the charging start state. The charging current I _RS of each battery cell 100 being charged is constant. Therefore, the remaining capacity C _a of the most deteriorated battery cell 100 and the remaining capacity C _b of the least deteriorated battery cell 100 increase linearly with the same slope.

As shown in FIG. 16A, the voltage Vb of the battery cell 100 that is least deteriorated is higher than the voltage Va of the battery cell 100 that is most deteriorated when starting charging. However, most because the full charge capacity towards the degraded battery cell 100 is small, the most degraded voltage V _a of the battery cell 100, higher than the faster voltage V _b of the battery cells 100 is least degraded. Thus, at time t _a, the most degraded voltage V _a of the battery cell 100 is greater than the voltage V _b of battery cells is least degraded. Accordingly, the control unit 400, at the time t _a later, identifies the cell 100 that is degraded most as "maximum voltage cell". On the other hand, the control unit 400 identifies the battery cell 100 that is least deteriorated as a “minimum voltage cell”.

Then, at time _{t 1,} the voltage _{V a} of the voltage maximum cell reaches the first reference voltage _{V 1.} At this time, since the first condition is satisfied, the control unit 400 performs the first control. Alternatively, the control unit 400 operates the balance circuit 200. Here, the 1st reference voltage V1 is more than a rated charge voltage and less than an overcharge protection voltage, for example. Thus, by determining the first condition in the battery cell 100 that is nearly fully charged, the battery cell 100 that is most degraded can be identified as the maximum voltage cell. The subsequent charging method is the same as that of the first embodiment.

According to the sixth embodiment, the battery cell 100 is recycled. For this reason, since each battery cell 100 which comprises the battery pack 10 differs in use time, the degree of deterioration is also different. The most deteriorated battery cell 100 has a fast voltage increase. By applying the control system and the charging method of the first embodiment to such a battery pack 10, it is possible to prevent the maximum voltage unit from being overcharged. Therefore, even if the battery cell 100 is recycled, each battery cell 100 can be safely brought close to full charge.

(Seventh embodiment)
FIG. 17 is a diagram for explaining a charging method according to the seventh embodiment. The seventh embodiment is the same as the first embodiment or the second embodiment except for the following points. The balance circuit 200 has a function of moving power from one battery cell 100 to another battery cell 100. In addition, when the control unit 400 satisfies the first condition and activates the balance circuit 200, the control unit 400 causes the balance circuit 200 to move power from the maximum voltage cell to another battery cell 100. Details will be described below.

FIG. 17A shows the relationship between the time and the voltage of the battery cell 100 in the seventh embodiment. As shown in FIG. 17 (a), the are indicated by thick solid lines a voltage of the voltage maximum cell as V _a. The voltage of the minimum voltage cell is indicated by a thin solid line as _Vb .

FIG. 17B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the seventh embodiment.

As in FIG. 17 (a), the control unit 400, the start of charging to time t _1, for charging in the same manner as in the first embodiment. Like the first embodiment, the voltage V _a of the voltage maximum cell rises faster than the voltage V _b of the voltage minimum cell. At time _{t 1,} the voltage _{V a} of the voltage maximum cell, reaches the first reference voltage _{V 1.}

At time _{t 1,} the voltage _{V a} of the voltage maximum cell becomes the first reference voltages _{V 1} or more, since the first condition is satisfied, the control unit 400 actuates the balance circuit 200. The balance circuit 200 according to the fourth embodiment has a function of transferring power from one battery cell 100 to another battery cell 100. The control unit 400 causes the balance circuit 200 to move power from the maximum voltage cell to another battery cell 100. Thus, lowering the voltage V _a of the voltage maximum cell.

In addition, when power is transferred from the maximum voltage cell to another battery cell 100 by the balance circuit 200, the “other battery cell 100” is not particularly limited. The balance circuit 200 may move power from the maximum voltage cell to the minimum voltage cell. On the other hand, the balance circuit 200 may move power from the maximum voltage cell to another battery cell 100 different from the minimum voltage cell. Here, a case where the balance circuit 200 moves power from the maximum voltage cell to the minimum voltage cell will be described.

From the time _{t 1} shown in FIG. 17 (a) over the time _{t 2, the} control unit 400 is to operate the balance circuit 200. The balance circuit 200, since the power is being moved to another cell 100, the voltage V _a of the voltage maximum cell drops. On the other hand, the voltage V _{b of the} minimum voltage cell is charged and increased by the power supplied from the maximum voltage cell. Note that the slope of the increase in voltage of the minimum voltage cell or the like depends on the voltage difference between the maximum voltage cell and the battery cell 100 at time t ₁ . In addition, the gradient in which the voltage of the minimum voltage cell or the like increases is gentler than the gradient in which the voltage increases due to charging by another power source.

Over a time t ₂ from time t ₁ in FIG. 17 (b), the residual capacity C _b of the voltage minimum cell also increases are charged by power supplied from the voltage maximum cell. In addition, a current flows from the maximum voltage cell with respect to the minimum voltage cell. And from time t ₁ to time t _2, the with the drop of the voltage V _a of the voltage maximum cell, the current flowing through the voltage minimum cell decreases.

Then, in FIGS. 17 (a) and 17 FIG. 17 (b), the time of time _{t 2, the} since the voltage _{V a} of the voltage maximum cell becomes a second reference voltage _{V 2,} the control unit 400 stops the balance circuit 200 , Resume charging.

Thereafter, similarly to the second embodiment, S120 to S170 of FIG. 9 are repeatedly performed. As shown in FIG. 17 (a), the at time _{t 8} from the time _{t 2, the} voltage _{V a} of the voltage maximum cell rises due to charging, repeated drop by balance circuit 200.

On the other hand, the voltage V _b of the voltage minimum cell, as in the second embodiment, when operating the balance circuit 200, does not become a constant voltage. That is, the voltage V _b of the voltage minimum cell repeats rise due to the charging, the voltage rise due power supply from the voltage maximum cell.

At this time, as shown in FIG. 17B, in the first control step (S160) at time t ₁ , time t ₃ , time t ₅ and time t ₇ , the current flowing from the voltage maximum cell to the voltage minimum cell is It gradually decreases according to the voltage difference between the largest cell and the smallest voltage cell.

As described above, faster than the first embodiment, it is possible to make the voltage V _b of the voltage V _a and the voltage minimum cell voltage maximum cell. Also, faster than the first embodiment, the remaining capacity C _b of the voltage minimum cell, can be brought close to the full charge capacity C _Rb.

According to the seventh embodiment, the same effect as that of the second embodiment can be obtained. Further, according to the seventh embodiment, the control unit 400 operates the balance circuit 200 to move power from the maximum voltage cell to another battery cell 100. Thus, the electric power for lowering the voltage V _a of the voltage maximum cell can be used to charge the other battery cells 100. Moreover, when the control part 400 operates the balance circuit 200, charge of the other battery cell 100 is not interrupted like 1st Embodiment. Thereby, it can approach full charge earlier than 1st Embodiment.

(Eighth embodiment)
The eighth embodiment will be described with reference to FIGS. 18 and 19. FIG. 18 is a flowchart showing a charging method according to the eighth embodiment. FIG. 19 is a diagram for explaining a charging method according to the eighth embodiment. The eighth embodiment is the same as part of the first embodiment, the second embodiment, or the fourth embodiment except for the following points. Controller 400 fills the first condition, since by actuating the balance circuit 200, when the voltage V _a of the voltage up unit becomes equal to the other battery cells 100, the other battery cells 100 as a voltage up unit Control all at once. Details will be described below.

In the above embodiment, the control part 400 demonstrated the method of specifying one battery cell 100 with the largest voltage as a "voltage largest cell", and controlling a voltage. On the other hand, in the eighth embodiment, the “maximum voltage unit” refers to a set of one or more battery cells 100 including the maximum voltage cell. For example, when the “maximum voltage cell” becomes the same voltage as the battery cell 100 having the next highest voltage, the control unit 400 controls the plurality of battery cells 100 as a “maximum voltage unit”. Hereinafter, a set of battery cells 100 including “maximum voltage cell” is referred to as “maximum voltage unit”. Further, the battery cell 100 having the second highest voltage after the “maximum voltage cell” will be described as a “second voltage cell”.

As shown in FIG. 18, as in the second embodiment, charging is started and the voltage and current of the battery cell 100 are measured (S110).

Next, the control unit 400 identifies the “maximum voltage unit” and “minimum voltage cell” based on the voltage measured by the measurement unit 300 (S120). In this initial stage, the “voltage maximum unit” is one “voltage maximum cell”.

Here, FIG. 19A shows the relationship between the time and the voltage of the battery cell 100 in the eighth embodiment. In FIG. 19A, the voltage of the “voltage second cell” is indicated by a bold dotted line as V _c .

FIG. 19B shows the relationship between the time and the remaining capacity of the battery cell 100 and the relationship between the time and the current of the battery cell 100 in the eighth embodiment. In FIG. 19B, the remaining capacity of the “voltage second cell” is indicated by a thick dotted line as C _c .

As shown in FIG. 19 (a), the earliest increase in the voltage V _a of the voltage maximum cell. Increase in the voltage V _c of the voltage the second cell is also faster than the voltage V _b of the voltage minimum cell. Note that as in FIG. 19 (b), until the time t _1, the remaining capacity of all of the battery cells 100, rises linearly.

At time _{t 1,} the voltage Va of the voltage maximum cell, the first reference voltages _{V 1,} and the first condition is satisfied (S130Yes). Further, at time t _1, since a large voltage difference between the voltage maximum cell voltage minimum cell, the second condition is a termination condition of the charging does not satisfy (S140No).

At this time, the control unit 400 temporarily stops the charging of all the battery cells 100 (S150). Next, the control unit 400 operates the balance circuit 200 (S160).

As shown in FIG. 19 (a), the at time _{t 1} after the control unit 400 operates the balance circuit 200. At time _{t c} from the time _{t 1,} the internal resistance of the balance circuit 200, the voltage _{V a} of the voltage maximum cell drops. Meanwhile, since the charging is suspended, the voltage V _b and the voltage voltage V _c of the second cell voltage minimum cell is hardly lowered.

As shown in FIG. 19 (b), the at time _{t c} from the time _{t 1,} the residual capacity _{C b} and the voltage remaining capacity _{C c} of the second cell voltage minimum cell remains constant. Further, since the battery is not charged, the current is zero.

Next, it is determined whether or not the voltage of the maximum voltage unit is equal to the voltage of the voltage second cell while the balance circuit 200 is operating (S310). When the voltage of the voltage maximum unit is not equal to the voltage of the voltage second cell (S310 No), the control unit 400 operates the balance circuit 200 until S170 with the voltage maximum unit as one voltage maximum cell.

As shown in FIG. 19A, at time t _c , the voltage V _a of the voltage maximum unit (here, only the voltage maximum cell) is equal to the voltage V _c of the voltage second cell.

Thus, when the voltage _{V a} of the voltage up unit equal to the voltage _{V c} voltage second cell (S310Yes), the control unit 400 include a voltage second cell voltage maximum unit (S320). Here, “included in the maximum voltage unit” means that the control unit 400 collectively controls the plurality of battery cells 100 as the maximum voltage unit. Accordingly, the control unit 400 operates the balance circuit 200 using the voltage maximum cell and the voltage second cell as the voltage maximum unit.

As shown in FIG. 19A, after time t _c , the voltage V _c of the voltage second cell included in the maximum voltage unit drops together with the voltage V _{a of the} maximum voltage cell. Further, as shown in FIG. 19B, the remaining capacity C _c of the voltage second cell drops due to power consumption by the internal resistance of the balance circuit 200.

Then, it is determined whether the voltage of the voltage up unit becomes the second reference voltage _{V 2} (S170). When the voltage of the voltage up unit not the second reference voltage _{V 2} (S170No), the control unit 400 operates the balancing circuit 200 continues. At this time, when the voltage of the maximum voltage unit becomes equal to the next voltage second cell (in the case of S310 Yes), the control unit 400 can include the voltage second cell in the maximum battery unit.

Then, when the time t _2, the voltage of the voltage up unit including a voltage second cell becomes a second reference voltage V _2.

Thus, when the voltage of the voltage up unit becomes the second reference voltage _{V 2} (S170Yes), the control unit 400, a balance circuit 200 is stopped, to resume charging of the battery cell 100 (S180).

Thereafter, the voltage maximum unit repeats an increase due to charging and a decrease in the first control step (S160). Subsequent steps are the same as those in the first embodiment except that the maximum voltage unit is a plurality of battery cells 100.

As described above, after the time t _c, the control unit 400 controls the voltage second cell as the voltage up unit. After S180, when the voltage of the second voltage cell is significantly different from that of the maximum voltage unit, the control unit 400 may exclude the second voltage cell from the maximum voltage unit in S120.

Moreover, the control part 400 can make the battery cell 100 with the next largest voltage next to the said voltage 2nd cell into a new voltage 2nd cell by including a voltage 2nd cell in a voltage maximum unit. That is, from S310 to S320, the control unit 400 can gradually increase the voltage maximum unit. Finally, the above charging method can be repeated until the voltage of the voltage maximum unit becomes equal to the voltage of the voltage minimum cell.

According to the eighth embodiment, the control unit 400 collectively controls a plurality of battery cells 100 having the same voltage as the maximum voltage unit. Thereby, the voltage of the some battery cell 100 can be arrange | equalized quickly.

(Ninth embodiment)
FIG. 20 is a circuit diagram showing configurations of the battery pack 10 and the control circuit 20 according to the ninth embodiment. The ninth embodiment is the same as the second embodiment except that the control circuit 20 is provided outside the battery pack 10. Details will be described below.

As shown in FIG. 20, the control circuit 20 is provided outside the battery pack 10. The control circuit 20 is provided in, for example, a charging device (not shown) independent from the battery pack 10. Alternatively, the control circuit 20 may be provided in a device used when the battery pack 10 is discharged and used.

As in the first embodiment, a plurality of battery cells 100 are connected in series to the battery pack 10. The battery pack 10 is provided with a positive electrode terminal 820 and a negative electrode terminal 840 for charging and discharging the battery pack 10. In addition, battery cell terminals 830 are provided between the battery cells 100.

The control circuit 20 includes a balance circuit 200, a measurement unit 300, and a control unit 400. A balance circuit 200 is provided on the battery pack 10 side of the control circuit 20. Further, the positive terminal 920 and the negative terminal 940 of the control circuit 20 are provided on the battery pack 10 side of the control circuit 20. The positive terminal 920 and the negative terminal 940 of the control circuit 20 are connected to the positive terminal 820 and the negative terminal 840 of the battery pack 10 through wiring (not shown), respectively. As a result, charging power is supplied from the control circuit 20 side to the battery pack 10.

Further, a measurement terminal 930 of the balance circuit 200 is provided on the battery pack 10 side of the control circuit 20. The measurement terminal 930 of the balance circuit 200 is connected to the battery cell terminal 830 of the battery pack 10 via wiring (not shown). Thereby, even if the control circuit 20 is provided outside the battery pack 10, each battery cell 100 can be controlled when the balance circuit 200 is operated.

According to the ninth embodiment, the control circuit 20 is provided outside the battery pack 10. The balance circuit 200 is connected to each battery cell 100 via wiring. Thereby, the effect similar to 1st Embodiment can be acquired.

(Tenth embodiment)
FIG. 21 is a circuit diagram showing configurations of the battery pack 10 and the control circuit 20 according to the tenth embodiment. The tenth embodiment is the same as the fifth embodiment except that the control circuit 20 other than the balance circuit 200 is provided outside the battery pack 10. Details will be described below.

As shown in FIG. 21, the balance circuit 200 is provided in the battery pack 10. On the other hand, the control circuit 20 including the measurement unit 300 and the control unit 400 excluding the balance circuit 200 is provided outside the battery pack 10.

In the battery pack 10, the balance circuit 200 is connected to each battery cell 100. The battery pack 10 is provided with a positive electrode terminal 820 and a negative electrode terminal 840 for charging and discharging the battery pack 10. In addition, a balance circuit terminal 860 for transmitting and receiving signals to and from the balance circuit 200 is provided.

A measuring unit 300 is provided on the battery pack 10 side of the control circuit 20. Further, the positive terminal 920 and the negative terminal 940 of the control circuit 20 are provided at positions corresponding to the positive terminal 820 and the negative terminal 840 of the battery pack 10 on the battery pack 10 side of the control circuit 20.

The measurement unit terminal 960 is provided at a position corresponding to the balance circuit terminal 860 on the battery pack 10 side of the measurement unit 300. The balance circuit terminal 860 and the measurement unit terminal 960 are connected to each other by wiring (not shown). Thereby, the signal which operates the balance circuit 200, and the signal of the voltage and electric current from the battery cell 100 can be transmitted / received via wiring.

According to the tenth embodiment, the same effects as those of the ninth embodiment can be obtained.

In the above ninth embodiment and tenth embodiment, the case where the control circuit 20 is provided outside the battery pack 10 has been described, but various other configurations are possible. For example, only the control unit 400 may be provided outside the battery pack 10.

As described above, in the first to tenth embodiments, the case where the control unit 400 transmits a signal to the switch 500 via the measurement unit 300 has been described. However, the control unit 400 directly transmits a signal to the switch 500. May be transmitted.

In the above embodiment, a charging device including the above-described control circuit 20 is also disclosed.

In the above embodiments, the control unit 400, based on the first reference voltage V _1, or lowering the voltage of the voltage maximum cell has been described a case in which or to bypass the voltage maximum cell. The first reference voltages V ₁ may go by any time changes in the control. In this case, for example, in the initial stage of the charging, the control unit 400, a first reference voltages V ₁ and the rated charging voltage, rated charge the first reference voltages V ₁ from all of the battery cells 100 is approaching full charge It may be a voltage.

As described above, the embodiments of the present invention have been described with reference to the drawings. However, these are exemplifications of the present invention, and various configurations other than the above can be adopted.

This application claims priority based on Japanese Patent Application No. 2011-152372 filed on July 8, 2011, the entire disclosure of which is incorporated herein.

Claims

A measuring unit for measuring voltages of a plurality of battery units connected in series;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
A charge control system that performs a first control to drop the voltage of the maximum voltage unit when the first condition is satisfied.
The charge control system according to claim 1,
The charge control system further includes a balance circuit that adjusts the charge amount of each of the battery units,
The controller is
Controlling the operation of the balance circuit;
A charge control system that performs the first control by operating the balance circuit when the first condition is satisfied.
In the charge control system according to claim 2,
The balance circuit has a function of transferring power from one battery unit to another battery unit,
The controller is
When the first control is performed by satisfying the first condition and operating the balance circuit, the charge control system moves the power from the maximum voltage unit to another battery unit by the balance circuit.
The charge control system according to any one of claims 1 to 3,
The controller is
When the first condition is satisfied, a charging control system that temporarily stops the charging and performs the first control.
In the charge control system according to any one of claims 1 to 4,
The controller is
After satisfying the first condition and performing the first control, when the voltage maximum unit becomes a second reference voltage lower than the first reference voltage, the first control is stopped and the charging is resumed. Let the charge control system.
In the charge control system according to any one of claims 1 to 5,
The controller is
A charging control system that satisfies the first condition and stops the first control and restarts the charging when an operation time during which the first control is performed becomes a first reference time or more.
The charging control system according to any one of claims 1 to 6,
The controller is
Based on the voltage measured by the measurement unit, further specifies a voltage minimum unit in which the voltage is minimum,
A charge control system that performs the first control when the first condition is satisfied and a second condition that a voltage difference between the maximum voltage unit and the minimum voltage unit is less than a predetermined value is not satisfied.
The charge control system according to claim 7,
A charging control system that terminates the charging when the first condition is satisfied and the second condition is satisfied.
The charge control system according to any one of claims 1 to 8,
The controller is
A charge control system that performs the first control when the first condition is satisfied and a third condition that an integrated value of the number of times of performing the first control during the charging is not less than a predetermined value is not satisfied.
The charge control system according to claim 9,
A charging control system that terminates the charging when the first condition is satisfied and the third condition is satisfied.
The charging control system according to any one of claims 1 to 10,
The controller is
A charge control system that terminates the charge when a charge time obtained by integrating the charge times during the charge satisfies a fourth condition that a second reference time that is longer than the first reference time has elapsed.
The charge control system according to any one of claims 1 to 11,
The measurement unit further measures the current of the battery unit,
The controller is
The charge control system which continues the said charge when the 5th condition that the said current of each said battery unit is below a reference current is not satisfy | filled.
The charge control system according to claim 12,
A charging control system that terminates the charging when the fifth condition is satisfied.
The charging control system according to any one of claims 1 to 13,
The controller is
When the voltage of the maximum voltage unit becomes equal to the other battery units after satisfying the first condition and performing the first control, the other battery units are collectively controlled as the maximum voltage unit. Charge control system.
The charging control system according to any one of claims 1 to 14,
The controller is
A charging control system that transmits a signal for switching the charging from a constant voltage to a constant current to an external charging device when the voltage of the minimum voltage unit becomes equal to or higher than the first reference voltage.
A measuring unit for measuring voltages of a plurality of battery units connected in series;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, the charging control system performs bypass control for bypassing the maximum voltage unit as a bypass target unit and continuing the charging for the battery units other than the bypass target unit.
The charge control system according to claim 16, wherein
The charge control system further includes a balance circuit that adjusts the charge amount of each of the battery units,
The controller is
Controlling the operation of the balance circuit;
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
A charge control system that performs the bypass control by operating the balance circuit when the first condition is satisfied.
The charge control system according to claim 16 or 17,
The controller is
After satisfying the first condition and performing the bypass control, update the new voltage maximum unit at which the voltage is currently maximum,
When the new maximum voltage unit does not satisfy the first condition, the battery unit other than the bypass target unit is continuously charged,
A charging control system that includes the new voltage maximum unit in the bypass target unit when the new voltage maximum unit satisfies the first condition.
The charge control system according to claim 18,
The charge control system which transmits the signal which shows the number of the said battery units bypassed as said bypass object unit by the said bypass control to an external charging apparatus.
The charging control system according to any one of claims 16 to 19,
The controller is
Based on the voltage measured by the measurement unit, further specify the voltage minimum unit that is the minimum voltage among the battery cells other than the bypass target unit,
A charge control system that stops the bypass control when the voltage of the minimum voltage battery cell becomes equal to or higher than a first reference voltage after satisfying the first condition and performing the bypass control.
The charge control system according to claim 20,
The controller is
A charge control system that transmits a signal for switching the charge from a constant current to a constant voltage to an external charging device after stopping the bypass control.
The charging control system according to any one of claims 16 to 19,
The controller is
Based on the voltage measured by the measurement unit, further specify the voltage minimum unit that is the minimum voltage among the battery cells other than the bypass target unit,
A charge control system that bypasses all the battery units for a predetermined time when the voltage of the minimum voltage battery cell becomes equal to or higher than a first reference voltage after satisfying the first condition and performing the bypass control.
The charge control system according to claim 22,
The controller is
A charge control system for transmitting a signal for switching the charging from a constant current to a constant voltage to an external charging device after bypassing all the battery units for a predetermined time.
The charging control system according to any one of claims 20 to 23,
The controller is
A charge control system that resumes charging when the voltage of the minimum voltage unit satisfies the first condition after satisfying the first condition and performing the bypass control.
The charging control system according to any one of claims 16 to 24,
The controller is
The charge control system which transmits the signal for dropping the charge voltage applied by the charge by the voltage of the voltage maximum unit to the external charging device after satisfying the first condition and performing the bypass control.
The charging control system according to any one of claims 1 to 25,
The charge control system, wherein the first reference voltage is equal to or higher than a rated charge voltage and lower than an overcharge protection voltage.
In the charge control system according to any one of claims 1 to 26,
The battery unit is a charge control system that is recycled.
A plurality of battery units connected in series;
A measurement unit for measuring the voltage of the battery unit;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
A battery pack that performs first control to drop the voltage of the maximum voltage unit when the first condition is satisfied.
A plurality of battery units connected in series;
A measurement unit for measuring the voltage of the battery unit;
Based on the voltage measured by the measurement unit, a control unit that controls charging to each of the battery units,
With
The controller is
When performing the charging to the battery unit, based on the voltage measured by the measurement unit, identify the voltage maximum unit that the voltage is maximum,
When the first condition that the voltage of the voltage maximum unit is equal to or higher than the first reference voltage is not satisfied, the charging is continued for all the battery units,
When the first condition is satisfied, the battery pack performs bypass control for bypassing the maximum voltage unit as a bypass target unit and continuing the charging for the battery units other than the bypass target unit.
A charging start step for measuring voltages of a plurality of battery units connected in series and starting charging the plurality of battery units;
A unit identification step for identifying a voltage maximum unit in which the voltage is maximum based on the measured voltage;
A first determination step of determining a first condition that the voltage of the voltage maximum unit is equal to or higher than a first reference voltage;
When the first condition is not satisfied, the charging is continued for all the battery units, and when the first condition is satisfied, the first control step of decreasing the voltage of the maximum voltage unit;
A charging method comprising:
A charging start step for measuring voltages of a plurality of battery units connected in series and starting charging the plurality of battery units;
A unit identification step for identifying a voltage maximum unit in which the voltage is maximum based on the measured voltage;
A first determination step of determining a first condition that the voltage of the voltage maximum unit is equal to or higher than a first reference voltage;
When the first condition is not satisfied, the charging is continued for all the battery units, and when the first condition is satisfied, the voltage maximum unit is bypassed as a bypass target unit, and other than the bypass target unit. A bypass control step for continuing the charging for the battery unit;
A charging method comprising: