JP2015213384A - Battery voltage compensation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery voltage compensation system capable of achieving high efficiency and miniaturization.SOLUTION: A battery voltage compensation system 3 includes: a main battery 31 which is connected to the side of a communication device 4 and supplies power to the communication device 4; an end battery 32; a booster converter 33 to which an output terminal of the end battery 32 is connected in series and which adjusts a voltage of the end battery 32 and supplies power to the communication device 4; a voltage detector 40 for detecting a terminal voltage of the communication device 4; and a control unit 60 which instructs, on the basis of the detection result, the booster converter 33 to step up or step down the voltage of the end battery 32 so that the terminal voltage becomes a specified value or lower.

Description

  The present invention relates to a battery voltage compensation system that adjusts the voltage of a storage battery and supplies power to a load.

  Conventionally, when power is supplied via a booster converter and the input voltage of the boost converter drops below the standard value, the output voltage generated according to the fluctuation is superimposed on the input voltage of the booster converter to maintain the voltage standard A system is known (Non-Patent Document 1). The booster converter generates a boosted voltage of several volts and superimposes it on the input voltage so as to compensate the voltage of the power feeding system within a certain range.

FIG. 1 is a diagram illustrating a configuration of a conventional power supply system 100.
In FIG. 1, the power supply system 100 includes an alternating current system (commercial power supply) and a direct current system (direct current power supply), and the RF (rectifying device) 101 receives power supply from the alternating current system in a normal state. DC power is supplied to the communication device (load device) 200. Further, in a normal state, the charging device 102 receives the AC system power supply and charges the storage battery 103 in a flow manner.
On the other hand, when an abnormal state such as a power failure occurs and the power supply to the RF 101 and the charging device 102 is stopped, the storage battery 103 supplies DC power to the communication device 200 via the booster converter 104.

FIG. 2 is a diagram illustrating a configuration of the booster converter 104.
In FIG. 2, the voltage of the storage battery 103 is supplied to the communication device 200 via the boost converter 104.
Boost converter 104 includes semiconductor switch 11, transformer 12, diodes 13, 14, 15, reactor 16, and capacitor 17.
In boost converter 104, semiconductor switch 11 is turned off or on according to the voltage of communication device 200, and the voltage of storage battery 103 is adjusted to supply power to communication device 200.

In FIG. 2, the bypass diode 105 functions to drop the voltage immediately after a power failure occurs. Generally, immediately after the occurrence of a power failure, it is known that the voltage of the storage battery 103 may be several volts higher than the input voltage (for example, 48 V) of the communication device 200 (see FIG. 3.48 of Non-Patent Document 1). reference). For this reason, the voltage of the capacitor is lowered by the bypass diode 105 so that the above-described input voltage is within the allowable range.
The electromagnetic contactor 106 is composed of a contact and a contact, and is connected to or disconnected from the circuit on the communication device 200 side.

  The booster converter 104 allows the storage battery 103 to be used up to the end voltage of the discharge even when the storage battery 103 is discharged even if there is a voltage drop due to the wiring by the boosting function. For this reason, the utilization factor of the storage battery 103 improves. In addition, the boosting / lowering function of the booster converter 104 can reduce the range of voltage to be supplied, so that the power supply efficiency on the communication device 200 side is improved.

Information / communication power supply, energy technology supporting multimedia, Ohm Co., Ltd., Communication Power Supply Study Group, p96-p97, published on March 30, 1998

  In the conventional battery voltage compensation system, the voltage supplied to the load side is allowed by the step-up / down function of the booster converter. However, since the voltage of the entire storage battery is applied to the input side of the booster converter, the battery voltage compensation system has a problem that efficiency is reduced due to conduction loss of the booster converter. Moreover, since the voltage for the entire storage battery is applied to the input side of the booster converter, there is a problem that it is difficult to reduce the size of the battery voltage compensation system.

  The present invention has been made to cope with such problems, and an object thereof is to provide a battery voltage compensation system capable of realizing high efficiency and miniaturization.

  An invention for solving the above problems is a battery voltage compensation system that compensates the voltage of a storage battery and supplies the load to a load, the first storage battery connected to the load side and supplying power to the load; 2 and a booster converter for connecting the output terminal of the second storage battery in series, adjusting the voltage of the second storage battery to supply power to the load, and a voltage for detecting the terminal voltage on the load side A detector, and a control unit that instructs the boost converter to step up or step down the voltage of the second storage battery based on a result of the detection so that the terminal voltage becomes a specified value or less.

  The boost converter may include a switching element, and the control unit may adjust the output voltage of the boost converter by instructing on or off of the switching element according to the detection result. .

  The control unit determines an on / off duty ratio of the switching element when the terminal voltage is larger than a specified value, and the boost converter controls the output voltage by on / off control of the switching element based on the duty ratio. You may make it adjust.

  According to the present invention, high efficiency and miniaturization can be realized.

It is a figure which shows the structure of the conventional electric power feeding system. It is a figure which shows the structure of the booster converter of FIG. It is a figure which shows the schematic structural example of the electric power feeding system containing the battery voltage compensation system of embodiment of this invention. It is a figure which shows the structural example of the booster converter of FIG. It is a flowchart which shows the operation example of a battery voltage compensation system. It is a figure which shows the relationship between the discharge capacity of a storage battery, and a voltage. It is a figure for demonstrating the procedure which determines the capacity | capacitance of a main battery and an end battery. It is a figure which shows the relationship between the discharge capacity and voltage of a single lithium ion battery. It is a figure which shows the relationship between the discharge capacity of a main battery, and a voltage. It is a figure which shows the discharge characteristic of a main battery.

  Hereinafter, embodiments of the battery voltage compensation system of the present invention will be described.

[Battery voltage compensation system configuration]
FIG. 3 is a diagram illustrating an example of a schematic configuration of the power feeding system 10 including the battery voltage compensation system 3 of the present embodiment.
As shown in FIG. 3, the power supply system 10 includes an AC system (commercial power supply) and a DC system (DC power supply), and the RF (rectifier device) 1 supplies power to the AC system at normal times. In response, DC power is supplied to the communication device (load device) 4. Further, in a normal state, the charging device 2 receives the power supply of the AC system, and flows and charges the main battery (first storage battery) 31 and the end battery (second storage battery) 32 in the battery voltage compensation system 3. .

  On the other hand, when power supply to the RF 1 and the charging device 2 is stopped during an abnormality such as a power failure, in the battery voltage compensation system 3, the main battery 3 supplies DC power to the communication device 4, and the end battery 32 The DC power is supplied to the communication device 4 via the booster converter 33. This configuration will be described later.

FIG. 4 is a diagram illustrating a configuration example of the booster converter 33.
As shown in FIG. 4, each voltage of the main battery 31 and the end battery 32 in the battery voltage compensation system 33 is configured to be charged by each of the charging devices 2.

  The battery voltage compensation system 33 is connected to the communication device 4 on the load side, the main battery 31 that supplies power to the communication device 4, the end battery 32, and the output terminal of the end battery 32 are connected in series. And a booster converter 33 that adjusts the voltage V and supplies it to the communication device 4. Further, the battery voltage compensation system 33 includes a voltage detector 40 that detects the terminal voltage Vcd of the communication device 4, and the terminal battery 32 so that the terminal voltage of the communication device 4 is equal to or less than a specified value based on the detection result. And a control unit 60 that instructs the boost converter 33 to step up or step down the voltage.

  Although the specified value described above is set in advance, in this embodiment, since the communication device 4 is assumed as a load device, for example, an allowable voltage value of the communication device 4 can be considered as the specified value.

The boost converter 33 includes a reactor 331, a semiconductor switch (switching element) 332, a diode 333, a capacitor 334, a bypass diode 336, and an electromagnetic contactor (MC) 335. The semiconductor switch 332 is composed of, for example, a power MOSFET, and is provided with a free-wheeling diode DL for driving a gate.
The magnetic contactor 335 is normally in a state in which the contact is a contact a and the main battery 31 and the communication device 4 are connected. However, when the terminal voltage Vcd is larger than a specified value voltage, the contact is a contact. A bypass diode 336 is connected between the main battery 31 and the communication device 4 between the a and the contact b. Further, when the terminal voltage Vcd is smaller than the specified voltage, the contact connects the boost converter 33 to the circuit of the main battery 31 and the communication device 4 at the contact b.

In FIG. 4, the control unit 60 includes an instruction unit 20 and a calculation unit 30. The computing unit 30 computes the on / off duty ratio of the semiconductor switch 332.
The instruction unit 20 is configured to output a control signal for controlling the duty ratio to the gate terminal of the semiconductor switch 332.

In the control unit 60 of this embodiment, the arithmetic unit 30 controls the duty ratio of on / off of the semiconductor switch 332 to control the output voltage of the boost converter 33 (voltage between ab in FIG. 4), that is, the voltage V of the end battery 32. Process to adjust. When the duty ratio is α, the output voltage of the boost converter 33 is V / (1−α).
As long as the process of adjusting the output voltage of the boost converter 33 is possible, any configuration can be adopted as the circuit configuration of the boost converter 33.

  Further, the circuit configuration of the boost converter 33 is an example, and any circuit configuration having a boosting function, a step-down function, and a step-up / step-down function may be used. In this case, the step-down function is suitable for making the input voltage of the communication device 4 correspond to the narrow range.

  As will be described later, in this battery voltage compensation system 33, the control unit 60 calculates the duty ratio described above when the power feeding system 10 is abnormal (such as during a power failure), that is, the voltage V of the end battery 32, that is, the boost converter 33. Although the output voltage is adjusted, normally, no current flows through the boost converter 33, the duty ratio is 0, and the on / off control of the semiconductor switch 332 is not performed.

  In FIG. 4, even when the semiconductor switch 332 remains off with the electromagnetic contactor 335 closed, the charging device 2 can basically supply current only in a single direction. It is considered that no current flows on the two sides. Even if it flows, the diode 333 connected to the booster converter 33 prevents the power flow to the charging device 2 side.

  Next, processing executed to adjust the output voltage of the boost converter 33 will be described with reference to FIGS. FIG. 5 is a flowchart showing an operation example of the battery voltage compensation system 3.

  For example, when a power failure of the power supply system 10 starts discharging the storage battery (in this embodiment, the main battery 31) that supplies power to the communication device 4, the voltage of the main battery 31 decreases (see S1). The detector 40 measures the terminal voltage Vcd of the communication device 40 (S2).

When the terminal voltage Vcd is smaller than the specified value Vth (YES in S3), the control unit 30 boosts the voltage of the storage battery (the main battery 31 and the end battery 32) with the boost converter 33 (S4). The specified value Vth is set in advance based on the voltage fluctuation range of the communication device 4 or the like. According to the flowchart of FIG. 5, in the control unit 60, the calculation unit 30 calculates the on / off duty ratio of the semiconductor switch 332 with respect to the terminal voltage Vcd. Then, the instruction unit 20 outputs a control signal for controlling the duty ratio to the gate terminal of the semiconductor switch 332. For example, when the duty ratio calculated by the calculation unit 30 is α, the output voltage of the boost converter 33 is V / (1−α). The value of α described above is determined from the terminal voltage Vcd and the specified value Vth.
As a result, in addition to the voltage of the main battery 31, a voltage of V / (1-α) is also applied to the communication device 40. That is, the terminal voltage Vcd is boosted by the end battery 32.

  In S4, when the discharge of the main battery 31 is finished or the power supply of the AC system is restored (YES), the discharge of the storage battery is stopped and the process is finished. If not (NO), the above-mentioned S1 Return to processing.

  In S3, when the terminal voltage Vcd is equal to or higher than the specified value Vth (NO), the control unit 30 causes the boost converter 33 to step down the voltage of the storage battery (the main battery 31 and the end battery 32) (S5). In the example of FIG. 5, in the control unit 60, the calculation unit 30 sets the on / off duty ratio of the semiconductor switch 332 to 0, so the on / off control of the semiconductor switch 332 is not performed. In this case, in the boost converter 33, the voltage V of the end battery 32 is supplied to the communication device 4 via the reactance 331 and the diode 333. As a result, when Vcd <Vth is not satisfied, the control unit 60 outputs a signal for disconnecting the contact of the electromagnetic contactor 335 to the electromagnetic contactor 335. In this case, the voltage is lowered by the bypass diode 336 in the circuit including the main battery 31, the communication device 4, and the bypass diode 336, and as a result, the terminal voltage Vcd is lowered.

  Next, the discharge capacities of the main battery 31 and the end battery 32 described above will be described with reference to FIG. FIG. 6 is a diagram showing the relationship between the discharge capacity and voltage of the main battery 31.

  As shown in FIG. 6, the voltage of the main battery 31 decreases as the discharge of the main battery 31 progresses. Therefore, the discharge capacity is represented by a discharge curve as indicated by v1, v2, and v3, for example. The discharge curves v1 to v3 approach the origin 0 side, which is the discharge start point, as the discharge current increases.

  In this embodiment, as an example of the discharge curve of the main battery 31, the necessary discharge capacity of the end battery 32 is examined when the discharge characteristic indicated by v <b> 1 is provided. In this case, the energy capacity Sb (Wh) that can be extracted from the main battery 31 is an integral value from the discharge start point 0 (FIG. 6) to the discharge end point c (FIG. 6), and is expressed by the following equation (1).

  In equation (1), v (Ah) varies depending on the value of the discharge current.

  The battery voltage compensation system 10 needs to supply a constant voltage to the communication device 4 from the discharge start point 0 to the discharge end point c shown in FIG. Therefore, the battery voltage compensation system 1 as a whole needs to have an energy capacity of So corresponding to the area surrounded by the points 0-abc shown in FIG.

  That is, when the energy capacity of the main battery 31 is Sb, the energy capacity Ss of the end battery 32 requires a capacity as shown by the following formula (2).

  Next, as an example of a single battery constituting the main battery 31, a lithium ion battery (for example, NCR18650 of Panasonic Corporation) is used, and the discharge capacity of the end battery 32 when the supply power of the power supply system 10 is 48v. This will be discussed with reference to FIGS.

  FIG. 7 shows a configuration example of the battery voltage compensation system 3 similar to that in FIG. 4 and shows a case where the electromotive force of the main battery 31 is 48v. In the example shown in FIG. 7, since the electromotive force for one single cell is 4v, the main battery 31 includes 12 single cells connected in series, and the 12 single cells are grouped into 10 groups. It is configured in parallel.

Figure 8 shows the relationship between the discharge capacity S ₁ and the voltage of the cell. In this example, the electromotive force of the single cell is reduced from 4v to about 2.7v. Discharge capacity S ₁ becomes an integrated value indicated by the above formula (1).

  FIG. 9 shows the relationship between the discharge capacity Sb and the voltage of the main battery 31 shown in FIG. In this example, the electromotive force of the main battery 31 is reduced from 48v to about 32v. The discharge capacity Sb is an integral value represented by the above formula (1).

  FIG. 10 shows the relationship between the discharge characteristics of the main battery 31 and the output voltage of the boost converter 33 shown in FIG. This shows the voltage to be compensated by the boost converter 33 according to the discharge of the main battery 31.

  In general, when the discharge current of the storage battery increases, the discharge capacity decreases. Based on this viewpoint, the end battery 32 is selected so that the discharge capacity Ss of the end battery 32 satisfies the discharge capacity Ss (the above formula (2)) shown in FIG.

  As described above, according to the battery voltage compensation system 3 of the present embodiment, the control unit 60 determines that the terminal voltage is equal to or lower than the specified value based on the detection result of the terminal voltage of the communication device 4. The boost converter 33 is instructed to increase or decrease the voltage of the battery 32. Thereby, high efficiency and miniaturization of the battery voltage compensation system 3 can be realized.

  In general, the on-resistance value during conduction of a semiconductor switch is composed of a contact resistance value between a metal and a source / drain, a sheet resistance of the source / drain, a resistance value of a channel region, and a resistance value of a drift region, and has a high breakdown voltage. The on-resistance increases as the value increases. For this reason, the loss at the time of conduction | electrical_connection becomes large. However, in the battery voltage compensation system 3 of the present embodiment, the storage battery is divided into the main battery 31 and the end battery 32, and the voltage V of the end battery 32 is applied to the semiconductor switch 332. For this reason, since the ON resistance value when the semiconductor switch 332 is conductive is reduced, the loss during conduction is also reduced, and as a result, the efficiency is improved.

As a result, the loss of the semiconductor switch 332 is reduced, and as a result, the heat sink for cooling the amount of heat generated by the loss is also reduced.
For example, even if the battery voltage compensation system 3 of the present embodiment is applied to an HVDC power supply system that supplies power at about 380 V, it is not necessary to configure a booster converter so that the voltage of the entire battery cell is applied as in the prior art. The booster converter 33 itself can also be reduced in size.

Generally, the capacitor 334 in the boost converter 33 has an energy of 1/2 (CV ² ) (where C is the capacitance of the capacitor and V is the terminal voltage of the capacitor capacitor), so growing. However, in the battery voltage compensation system 3 of the present embodiment, the capacitor 334 can be made small because the withstand voltage of the capacitor 334 is based on the output voltage V of the boost converter 33 as described above.

  In addition, this embodiment is not restricted to the example mentioned above, It can change. For example, as a charging method of the main battery 31 and the end battery 32, for example, the main battery 31 may be float charge, the end battery 32 may be trickle charge, and the booster converter 33 is configured as a bidirectional converter. It is also conceivable to charge the battery 31 and the end battery 32 together.

1 RF (rectifier)
2 Charging device 3 Battery compensation system 4 Communication device (load)
31 Main battery 32 End battery 33 Boost converter 332 Semiconductor switch

Claims (3)

A battery voltage compensation system that compensates the voltage of a storage battery and supplies it to a load,
A first storage battery connected to the load side and supplying power to the load;
A second storage battery;
A booster converter in which an output terminal of the second storage battery is connected in series, adjusts a voltage of the second storage battery, and supplies power to the load;
A voltage detector for detecting the terminal voltage on the load side;
And a control unit that instructs the boost converter to step up or step down the voltage of the second storage battery so that the terminal voltage becomes a specified value or less based on the detection result. Compensation system. The boost converter includes a switching element;
The battery voltage compensation system according to claim 1, wherein the control unit adjusts the output voltage of the boost converter by instructing to turn on or off the switching element according to the detection result. When the terminal voltage is larger than a specified value, the control unit determines an on / off duty ratio of the switching element,
The battery voltage compensation system according to claim 2, wherein the boost converter adjusts the output voltage by on / off control of the switching element based on the duty ratio.

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