JP2013162540A - Battery equalization device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance accuracy of equalization while taking advantage of the feature of equalization time shortening by a transformer coupling system, in the equalization control of the voltage of a battery pack constituted by connecting a plurality of battery cells.SOLUTION: A transformer balance circuit 105 performs individual equalization operation of each stack 103, via a switching element 110, a transformer 109, and a rectifier circuit 111 connected individually. A DSP107 calculates the voltage of the stack 103 based on the voltage of each battery cell 102 detected by a voltage monitoring section 106, determines a stack 103 for which equalization operation must be performed based on the voltage thus calculated, and makes a switching element 110 corresponding to the stack thus determined perform the equalization operation by instructing a switching operation corresponding to the equalization operation.

Description

  The present invention relates to a battery equalization apparatus and method for controlling voltage equalization of an assembled battery configured by connecting a plurality of battery cells.

  A so-called hybrid car, plug-in hybrid car, hybrid vehicle, hybrid electric vehicle or the like, which is equipped with a motor (electric motor) as a power source in addition to an engine or a transport machine (hereinafter referred to as “vehicle etc.”) is practical It has become. Furthermore, an electric vehicle that does not include an engine and drives the vehicle only by a motor is being put into practical use. As a power source for driving these motors, a lithium ion battery having a small size and a large capacity has been frequently used. And in such a use, a some battery cell is connected in series, for example, a battery block is comprised, and also it may be supplied as an assembled battery connected combining this battery block. A high voltage necessary for driving the motor of the vehicle is obtained by the series connection of the battery cells, and a necessary current capacity and a further high voltage can be obtained by connecting the battery blocks in combination in series and parallel.

  In this case, the characteristics of the lithium ion battery or the like greatly change depending on the temperature, and the remaining capacity and charging efficiency of the battery greatly change depending on the temperature of the environment in which the battery is used. This is especially true in environments where automobiles are used.

  As a result, in the battery cells constituting the battery block, the remaining capacity and the output voltage of each cell vary. When the voltage generated by each cell varies, it becomes necessary to stop or suppress the entire power supply when the voltage of one cell falls below the driveable threshold, resulting in reduced power efficiency. Resulting in. For this reason, the battery equalization control which equalizes the voltage of each cell is required. Furthermore, it is necessary to equalize the voltage between the battery blocks.

  As a conventional technique for battery equalization control, a so-called active battery equalization control technique is known in which discharge power from a battery cell that needs to be discharged is charged into a battery cell that needs to be charged.

  Further, an inductor (converter) coupling method is known as a specific first conventional technique of the active method. In this method, the first connection terminal of the inductor is connected to each first connection terminal to which the adjacent first and second battery cells are connected in common. In addition, the first switching element is connected between the second connection terminal of the first cell and the second connection terminal of the inductor. Further, the second switching element is connected between the second connection terminal of the second cell and the second connection terminal of the inductor. If the voltage of the first battery cell is higher than the voltage of the second battery cell, first, the first switching element is turned on to discharge the charge from the first battery cell and charge the inductor, The operation of repeatedly turning off the first switching element and turning on the second switching element to charge the inductor to the second battery cell is repeatedly performed. Conversely, if the voltage of the second battery cell is higher than the voltage of the first battery cell, first, the second switching element is turned on to discharge the charge from the second battery cell and charge the inductor, Then, the operation of repeatedly turning off the second switching element and turning on the first switching element to charge the inductor battery with the charge of the inductor is repeatedly executed. Then, when the voltages of the first and second battery cells become equal, both the first and second switching elements are turned off, and the equalization operation for the adjacent first and second battery cells is completed. .

  Since the inductor coupling method moves charges through the inductor based on the potential difference between two adjacent battery cells, energy exchange efficiency and accuracy are good, and if the voltage of each battery cell can be monitored with a predetermined accuracy, the accuracy It is possible to equalize voltages between adjacent battery cells with an accuracy according to the above.

  However, since this inductor coupling method exchanges energy between adjacent cells, there is a problem that it takes a long balance time when the number of battery cells connected in series is large. For example, when battery cells 1, 2, 3, 4 are connected in series in that order, when the voltage of battery cell 1 is low, the charge of battery cell 2 is transferred to battery cell 1, and the voltage of battery cell 2 is Since it decreases, the charge of the battery cell 3 is transferred to the battery cell 2, and the charge is moved in order, which takes time.

  An inductor + transformer system is known as a second conventional technique of the active system (for example, a technique described in Patent Document 1). In this system, in addition to the circuit configuration of the inductor coupling system, several consecutive battery cells in the series of battery cells are combined as a stack, and each winding of the transformer is connected to both terminals of each stack. In this method, by making the number of turns of each winding of the transformer the same, the voltage across each stack is equalized in units of a stack consisting of several battery cells, and the voltage between the battery cells in each stack is It is equalized by the inductor coupling method. In this method, the equalization time can be shortened compared to the inductor coupling method.

  However, since the number of windings of the transformer usually varies by several percent, in the second conventional method, power is not supplied equally between the stacks due to variations between the windings, resulting in variations in the voltage between the stacks. . For this reason, the second conventional method has a problem that it is not possible to achieve equalization accuracy of battery cells of about several tens of millivolts due to variations between transformer windings.

JP 2008-35680 A

  An object of the present invention is to improve the accuracy of equalization while taking advantage of the feature of shortening the equalization time by the transformer coupling method.

  An example of an aspect is configured as a battery equalizing device that equalizes voltages of a plurality of battery cells in an assembled battery configured by connecting a plurality of battery cells in series, and a predetermined number of batteries among the plurality of battery cells A circuit for equalizing a voltage between stacks by discharging or charging electric charges for each stack of a plurality of stacks of cells, and a switching element, a transformer, and a rectifier circuit connected individually for each stack Through the transformer balance circuit for performing individual equalization operations, a voltage monitoring unit for monitoring and detecting the voltage of each battery cell, and a stack based on the voltage of each battery cell detected by the voltage monitoring unit The voltage corresponding to the stack is calculated, the stack on which the equalization operation is to be performed is determined based on the calculated voltage, and the switching corresponding to the determined stack is performed. To perform the operation of the equalization instructs the switching operation corresponding to the operation of the equalization to the child and a balance controller.

  According to the present invention, it is possible to improve the accuracy of equalization while taking advantage of the feature of shortening the equalization time by the transformer coupling method.

It is a system configuration figure of this embodiment. It is a block diagram of the converter balance circuit in this embodiment. It is a block diagram of the translator balance circuit in this embodiment. It is a flowchart which shows the control operation of this embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a basic configuration diagram of the present embodiment.
A plurality of battery cells 102 are connected in series to form an assembled battery 101. In this embodiment, the assembled battery 101 is configured as a set of stacks 103 including a predetermined number of battery cells 102 continuously connected in series.

  The transbalance circuit 105 is a circuit that equalizes the voltage between the stacks 103 by causing the stacks 103 to discharge or charge. More specifically, the transformer balance circuit 105 performs an individual equalization operation via the switching element 110, the transformer 109, and the diode 111, which is a rectifier circuit, for each stack 103.

  In the embodiment of FIG. 1, in the transformer balance circuit 105, both terminals of the assembled battery 101 are connected to the primary winding of each transformer 109 via the switching element 110 connected to the transformer 109. Further, both terminals of the stack 103 are connected to the secondary winding of the transformer 109 via a diode 111 which is a rectifier circuit.

  The switch control unit 108 in the transbalance circuit 105 is an oscillation circuit that oscillates a pulse signal having a predetermined frequency and duty ratio designated by the DSP 107 described later. Each switching element 110 is, for example, an FET (field effect transistor), and performs a switching operation by a pulse signal from the switch control unit 108. With this switching operation, for example, if the average voltage for each stack 103 calculated from the total voltage of the assembled battery 101 is higher than the voltage across the stack 103 connected to each switching element 110, the voltage between the two becomes equal. Until that time, the stack 103 is charged via the secondary winding of the transformer 109 and the diode 111. Based on this charging operation, the equalizing operation of the stack 103 is executed.

  For each stack 103 constituting the assembled battery 101, the converter balance circuit 104 transfers electric charges discharged from one or more of the battery cells 102 in the stack 103 among the battery cells 102 in the stack 103. The voltage of the battery cells 102 in the stack 103 is equalized by charging one or more other battery cells. For example, the converter balance circuit 104 charges power discharged from each battery cell 102 in the stack 103 to adjacent battery cells in the stack 103 via a circuit including a switching element and an inductor.

The voltage monitoring unit 106 monitors the voltage of each battery cell 102 and detects it as a digital signal value.
A digital signal processor (DSP: Digital Signal Processor: hereinafter referred to as “DSP”) 107 functions as a balance control unit, and based on the digital signal value of the voltage of each battery cell 102 detected by the voltage monitoring unit 106, the digital signal Depending on the processing, either converter balance circuit 104 or transformer balance circuit 105 is selected and operated.

  Specifically, the DSP 107 calculates the voltage of the stack 103 based on the voltage of each battery cell 102 detected by the voltage monitoring unit 106. Then, the DSP 107 determines the stack 103 on which the equalization operation is to be performed based on the calculated voltage. The DSP 107 instructs the switching element 110 corresponding to the determined stack 103 to perform the equalization operation by instructing the switching operation corresponding to the equalization operation. For example, the DSP 107 supplies a pulse signal designating a frequency and a duty ratio to the switching element 110 in order to perform charging by applying a predetermined voltage to both ends of the determined stack 103 via the transformer 109.

  More specifically, the DSP 107 calculates the voltage of the entire assembled battery 101 based on the voltage of each battery cell 103 detected by the voltage monitoring unit 106, and divides the voltage by the number of stacks 103 in the assembled battery 101. To calculate the stack average voltage. If the DSP 107 determines for each stack 103 that the voltage calculated for the stack 103 is lower than the stack average voltage, the DSP 107 instructs the switch control unit 108 in the transbalance circuit 105 to perform switching corresponding to the stack 103. A switching operation by the element 110 is instructed. Specifically, the DSP 107 gives identification information of the switching element 110 that should output a pulse signal to the switch control unit 108 and specifies the frequency and duty ratio of the pulse signal. As a result, the switch control unit 108 in the transformer balance circuit 105 outputs a pulse signal having a specified frequency and duty ratio to the specified switching element 110. As a result, the designated switching element 110 starts a switching operation, and each transformer in the stack 103 to which the secondary winding of the transformer 109 is connected via the transformer 109 and the diode 111 to which the switching element 110 is connected. Charging to the battery cell 102 is started. Conversely, if the DSP 107 determines that the voltage calculated for the stack 103 is higher than the stack average voltage for each stack 103, the DSP 107 causes the switching element 110 corresponding to the stack 103 to use the switching element 110. Does not instruct switching operation. In this case, the charge is supplied from the entire assembled battery 101 to the transformer 109 corresponding to the other stack 103 during the equalization operation, so that each battery cell 102 configuring the stack 103 determined to have a high voltage Discharge occurs gradually. As a result, finally, the voltage of each battery cell 102 in the assembled battery 101 becomes uniform.

  Finally, for each stack 103, when the voltage calculated for the stack 103 becomes equal to the stack average voltage, the DSP 107 ends the equalization operation for the stack 103, and other remaining unprocessed stacks. The same equalization operation is executed for 103.

  As described above, in the present embodiment, in the transformer balance circuit 105, a circuit including the switching element 110, the transformer 109, and the diode 111 is individually provided for each stack 103. When the DSP 107 performs equalization control so that the voltage of the stack 103 is equal to the stack average voltage for each stack 103, the frequency and duty of the pulse signal applied to the switching element 110 corresponding to the stack 103 are determined. Determine the ratio precisely. As a result, the voltage charged in each stack 103 can be controlled with high accuracy.

Details of the converter balance circuit 104 of FIG. 1 are shown in FIG.
In FIG. 2, the stack 103 and the voltage monitoring unit 106 are the same as the parts having the same numbers in FIG.

  The converter balance circuit 104 includes a balance circuit 201, a DSP (digital signal processor) 202, and a switch control unit 203. The balance circuit 201 includes a plurality of inductors L and a plurality of switching elements SW for, for example, four battery cells 102 # 1 to # 4 constituting the stack 103. Specifically, the first terminal of the # 1 inductor L is connected to the common connection terminal of the # 1 and # 2 battery cells 102, and the # 2 inductor is connected to the common connection terminal of the # 2 and # 3 battery cells 102. The first terminal of L is connected to the common connection terminal of the battery cells 102 of # 3 and # 4, and the first terminal of the inductor L of # 3 is connected thereto. The second terminal of the # 1 inductor L is the common connection terminal for the # 1 and # 2 switching elements SW, and the second terminal of the # 2 inductor L is the common for the # 3 and # 4 switching elements SW. The second terminal of the # 3 inductor L is connected to the common connection terminal of the # 5 and # 6 switching elements SW. Further, the output terminal side of the # 1 battery cell 102 is connected to the single connection terminal of the # 1 switching element SW. The common connection terminal of the battery cells 102 of # 1 and # 2 is connected to the switching element SW of # 2. The common connection terminals of the # 2 and # 3 battery cells 102 are connected to the common connection terminals of the switching elements SW of # 2 and # 5. The output terminal side of the # 4 battery cell 102 is connected to the single connection terminal of the # 6 switching element SW.

  The switch control unit 203 is an oscillation circuit that oscillates a pulse signal having a predetermined frequency and duty ratio specified by the DSP 202. Each switching element SW of # 1 to # 6 is, for example, an FET (field effect transistor), and performs a switching operation by a pulse signal from the switch control unit 203.

  The voltage monitoring unit 106 detects the voltages at both ends of the battery cells 102 # 1 to # 4 constituting the stack 103 and outputs the detected voltage to the DSP 107 in FIG. 1 and the DSP 202 in FIG. 2 as digital values.

  In the configuration of the converter balance circuit 104 described above, when the DSP 202 determines to perform balance control between the battery cells 102 of # 1 and # 2, for example, the DSP 202 designates a predetermined frequency and duty ratio to the switch control unit 203. Then, the switching elements SW of # 1 and # 2 are instructed to operate. For example, the DSP 202 determines that the voltage of the # 1 battery cell 102 is higher than the voltage of the # 2 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the # 1 battery cell 102 is accumulated in the # 1 inductor L by the on / off operation of the # 1 switching element SW. Subsequently, the charge accumulated in the # 1 inductor L is charged in the # 2 battery cell 102 by the on / off operation of the # 2 switching element SW delayed by the duty ratio. Conversely, for example, the DSP 202 determines that the voltage of the # 2 battery cell 102 is higher than the voltage of the # 1 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the # 2 battery cell 102 is accumulated in the # 1 inductor L by the on / off operation of the # 2 switching element SW. Subsequently, the charge stored in the # 1 inductor L is charged in the # 1 battery cell 102 by the on / off operation of the # 1 switching element SW delayed by the duty ratio.

  Further, when the DSP 202 determines that the balance control between the battery cells 102 of # 2 and # 3 is to be performed, the DSP 202 designates a predetermined frequency and duty ratio to the switch control unit 203, and # 3 and # 4. Instructing the switching element SW to operate. For example, the DSP 202 determines that the voltage of the # 2 battery cell 102 is higher than the voltage of the # 3 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the # 2 battery cell 102 is accumulated in the # 2 inductor L by the on / off operation of the # 3 switching element SW. Subsequently, the charge accumulated in the # 2 inductor L is charged in the # 3 battery cell 102 by the on / off operation of the # 4 switching element SW delayed by the duty ratio. Conversely, for example, the DSP 202 determines that the voltage of the # 3 battery cell 102 is higher than the voltage of the # 2 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the # 3 battery cell 102 is accumulated in the # 2 inductor L by the on / off operation of the # 4 switching element SW. Subsequently, the charge accumulated in the # 2 inductor L is charged in the # 2 battery cell 102 by the on / off operation of the # 3 switching element SW delayed by the duty ratio.

  Furthermore, when the DSP 202 determines that the balance control between the battery cells 102 of # 3 and # 4 is to be performed, the DSP 202 designates a predetermined frequency and duty ratio to the switch control unit 203, and # 5 and # 6. Instructing the switching element SW to operate. For example, the DSP 202 determines that the voltage of the # 3 battery cell 102 is higher than the voltage of the # 4 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the # 3 battery cell 102 is accumulated in the # 3 inductor L by the on / off operation of the # 5 switching element SW. Subsequently, the charge stored in the # 3 inductor L is charged in the # 4 battery cell 102 by the on / off operation of the # 6 switching element SW delayed by the duty ratio. Conversely, for example, the DSP 202 determines that the voltage of the # 4 battery cell 102 is higher than the voltage of the # 3 battery cell 102 based on the voltage monitoring result of the voltage monitoring unit 106. In this case, first, the charge discharged from the battery cell 102 of # 4 is accumulated in the inductor L of # 3 by the on / off operation of the switching element SW of # 6. Subsequently, the charge stored in the # 3 inductor L is charged in the # 3 battery cell 102 by the on / off operation of the # 5 switching element SW delayed by the duty ratio.

  As described above, in the converter balance circuit 104, when it is determined that the balance control in the stack 103 is necessary as a result of the voltage monitoring of the battery cells 102 in the stack 103 by the voltage monitoring unit 106, # The inductors 1 to # 3 and the switching elements SW of # 1 to # 6 are sequentially selectively operated. As a result, balance control is sequentially performed between the battery cells 102 adjacent to each of the battery cells 102 of # 1 to # 4, and the operation is repeated, so that the operations of # 1 to # 4 in the stack 103 are finally performed. The voltage of the battery cell 102 becomes uniform.

In the configuration described above, the DSP 202 in FIG. 2 may be realized by the same DPS as the DSP 107 in FIG.
The operation of the transformer balance circuit 105 in the embodiment of FIG. 1 will be described in more detail. FIG. 3 is a diagram in which the circuit configuration corresponding to two stacks 103 is extracted from the transformer balance circuit 105 of FIG.

  In FIG. 3, for example, the voltages at both ends are measured for each stack 103 of # 1 and # 2 by the voltage monitoring unit 104 of FIG. Then, the DSP 107 in FIG. 1 compares each terminal voltage with a stack average voltage calculated in advance from the voltage of the entire assembled battery 101. As a result, when the DSP 107 determines that the voltages at both ends are lower than the stack average voltage in both the stacks 103 of # 1 and # 2, for example, both the # 1 and # 2 are given to the switch control unit 108. A switching operation in the switching element 110 is designated. Specifically, the DSP 107 instructs the switch control unit 108 to operate the switching elements 110 of # 1 and # 2, and each pulse signal supplied from the switch control unit 108 to each switching element 110. Indicates a set of frequency and duty ratio values. Thereby, a pulse signal is supplied from the switch control unit 108 to the switching elements 110 of # 1 and # 2, and each switching element 110 starts to operate. As a result, the charges from both terminals of the assembled battery 101 are supplied to the primary winding side of the # 1 and # 2 transformers 109, and the charges are transmitted to the secondary winding side of each transformer 109. Will be charged.

  Here, the voltage states in the stacks # 1 and # 2 have different internal resistance values, temperature characteristics, and the like, so it is ideal to control them with individual voltage and current characteristics.

In the present embodiment, the voltage and current values supplied to each stack 103 are precisely determined according to the frequency and duty ratio of the pulse signal supplied from the switch control unit 108 to each switching element 110 as shown below. Can do. Now, the number of turns of the primary winding of the transformer 109 is N1, and the number of turns of the secondary winding 202 is N2. The frequency of the pulse signal given from the switch control unit 108 to the switching element 110 is freq, the period is T, the pulse on time is t _on , the duty ratio is D, the voltage on the primary winding side is Vin, and the voltage on the secondary winding side is If the voltage is Vo, the following equation holds.

この式に基づいて図１のスイッチ制御部１０８からスイッチング素子１１０に与えるパルス信号の周波数ｆｒｅｑとデューティー比Ｄを制御することにより、スタック１０３に対する充放電の出力電圧Ｖo を変化させることができる。また、出力電力は次式に基づいて出力されることから、デューティー比の制御によって出力電力を変化させることができる。ただし、Ｌp は一次巻線のインダクタンス、Ｐは出力電力である。

By controlling the frequency freq and the duty ratio D of the pulse signal applied to the switching element 110 from the switch control unit 108 of FIG. 1 based on this equation, the charge / discharge output voltage Vo to the stack 103 can be changed. Further, since the output power is output based on the following equation, the output power can be changed by controlling the duty ratio. Where Lp is the inductance of the primary winding and P is the output power.

上記数１式および数２式に基づいて、スタック１０３の電圧値や別途算出された内部抵抗値に対応して設定した供給電圧値、電流許容値、出力したい電力、パルス周波数ｆｒｅｑから、スイッチ制御部１０８よりスイッチング素子１１０に与えるパルス信号のデューティー比を計算することができる。または、逆にデューティー比を任意で決定しおき、パルス周波数ｆｒｅｑを決定してもよい。ＤＳＰ１０７は、＃１および＃２のスタック１０３ごとに決定したパルス周波数ｆｒｅｑおよびデューティー比Ｄの各値組を、図１のスイッチ制御部１０８に指定する。この結果、スイッチ制御部１０８から＃１および＃２のスイッチング素子１１０に、それぞれ個別の周波数およびデューティー比を有するパルス信号が出力され、個別のスイッチング動作が実行される。以上のようにして、本実施形態では、各スタック１０３ごとに、精度の高い均等化動作を実施することが可能となる。

Based on the above Equation 1 and Equation 2, switch control is performed from the supply voltage value, current allowable value, power to be output, and pulse frequency freq set corresponding to the voltage value of the stack 103 and the separately calculated internal resistance value. The duty ratio of the pulse signal given to the switching element 110 from the unit 108 can be calculated. Alternatively, the pulse frequency freq may be determined by arbitrarily determining the duty ratio. The DSP 107 designates each set of values of the pulse frequency freq and the duty ratio D determined for each of the stacks # 1 and # 2 to the switch control unit 108 in FIG. As a result, pulse signals having individual frequencies and duty ratios are output from the switch control unit 108 to the switching elements 110 of # 1 and # 2, and individual switching operations are executed. As described above, in this embodiment, it is possible to perform a highly accurate equalization operation for each stack 103.

  Here, if the DSP 107 determines that the voltage across the stack 103 is higher than the stack average voltage in a certain stack 103, for example, the # 103 stack 103, the DSP 107 instructs the switch control unit 108 in the # 2 switching element 110. Switching operation is not specified. In this case, the charge is supplied from the entire assembled battery 101 to, for example, the # 1 transformer 109 corresponding to the # 1 stack 103 during the equalization operation, whereby each battery cell 102 constituting the # 2 stack 103 is supplied. The discharge starts gradually. As a result, finally, the voltages of the stacks 103 constituting the assembled battery 101 are aligned.

  FIG. 4 is a flowchart showing a control operation executed by the DSP 107 in FIG. This control operation is realized as an operation in which a processor (not shown) in the DSP 107 executes a control program stored in a memory (not shown). This control program is executed once or at a predetermined time interval, for example, when the vehicle equipped with the system of the present embodiment is turned off or when idling is started.

  First, the DSP 107 in FIG. 1 calculates the voltage of the entire assembled battery 101 based on the voltage of each battery cell 103 detected by the voltage monitoring unit 106, and divides the voltage by the number of stacks 103 in the assembled battery 101. An average stack voltage is calculated (step S401).

  Next, the DSP 107 compares the voltage calculated by the voltage monitoring unit 106 for each stack 103 with the stack average voltage calculated in step S401 (step S402).

  For the stack 103 that is determined to have a voltage lower than the stack average voltage in the comparison process in step S <b> 402, the DSP 107 notifies the switching control unit 108 in the transbalance circuit 105 to the switching element 110 corresponding to the stack 103. Gives identification information. Further, the DSP 107 designates the frequency and duty ratio of the pulse signal output from the switch control unit 108 to the switching element 110 (step S403). As a result, the switch control unit 108 in the transformer balance circuit 105 outputs a pulse signal having a specified frequency and duty ratio to the specified switching element 110. As a result, the designated switching element 110 starts a switching operation, and each transformer in the stack 103 to which the secondary winding of the transformer 109 is connected via the transformer 109 and the diode 111 to which the switching element 110 is connected. Charging to the battery cell 102 is started.

After a certain time has elapsed, the switching operation is stopped (step S404).
On the other hand, the DSP 107 performs the switching operation by the switching element 110 corresponding to the stack 103 for the stack 103 that is determined to have a voltage higher than the stack average voltage in the comparison processing in step S402. No instruction is given (step S405). As a result, the stack 103 is discharged as described above.

  After a certain time has elapsed after the processing in step S404 or S405, the DSP 107 again compares the voltage calculated by the voltage monitoring unit 106 for each stack 103 with the stack average voltage calculated in step S401. (Step S406).

  For the stack 103 that is determined to have a voltage lower than the stack average voltage in the comparison process in step S <b> 406, the DSP 107 notifies the switching control unit 108 in the transbalance circuit 105 to the switching element 110 corresponding to the stack 103. Switching control is designated (steps S406 → S403).

  Further, the DSP 107 performs the switching operation by the switching element 110 corresponding to the stack 103 for the stack 103 that is determined to have a voltage higher than the stack average voltage in the comparison processing in step S406. Do not instruct. If the stack 103 has been switching until now, the DSP 107 stops the switching operation of the switching element 110 corresponding to the stack 103 (step S405).

  The DSP 107 ends the equalization operation for the stack 103 that has been determined to have a voltage equivalent to the stack average voltage in the comparison processing in step S406.

  In the embodiment described above, the circuit configuration shown in FIG. 2 is adopted as the specific configuration of the converter balance circuit 104 in FIG. 1, but the configuration of the converter balance circuit 104 is not limited to this. For each stack 103, the charge discharged from one or more of the battery cells 102 in the stack 103 is transferred to one or more other battery cells 102 of the battery cells 102 in the stack 103. Any configuration of the converter balance circuit 104 may be adopted as long as the voltage of the battery cells 102 in the stack 103 is equalized by charging.

DESCRIPTION OF SYMBOLS 101 Assembly battery 102 Battery cell 103 Stack 104 Converter balance circuit 105 Transbalance circuit 106 Voltage monitoring part 107,202 DSP (digital signal processor)
108, 203 Switch control unit 109 Transformer 110 Switching element 111 Diode

Claims (8)

A battery equalizing device for equalizing voltages of a plurality of battery cells in a battery pack configured by connecting a plurality of battery cells in series,
Among the plurality of battery cells, a circuit that equalizes the voltage between the stacks by discharging or charging a charge for each stack of a plurality of stacks composed of a predetermined number of battery cells, and for each stack A transformer balance circuit that performs individual equalization operations via individually connected switching elements, transformers, and rectifier circuits;
A voltage monitoring unit for monitoring and detecting the voltage of each battery cell;
The voltage of the stack is calculated based on the voltage of each battery cell detected by the voltage monitoring unit, the stack on which the equalization operation is to be performed is determined based on the calculated voltage, and the determined A balance control unit that instructs the switching operation corresponding to the equalization operation to the switching element corresponding to the stack to execute the equalization operation;
A battery equalizing apparatus comprising: Both terminals of the assembled battery are connected to the primary winding of the transformer via the switching element connected to the transformer, and both terminals of the stack are connected to the secondary winding of the transformer via the rectifier circuit. Connected,
The battery equalizing apparatus according to claim 1. The balance control unit
Calculate the voltage of the entire assembled battery based on the voltage of each battery cell detected by the voltage monitoring unit, calculate the stack average voltage by dividing the voltage by the number of stacks in the assembled battery,
For each stack, if it is determined that the voltage calculated for the stack is lower than the stack average voltage, the switching element in the transbalance circuit corresponding to the stack is caused to perform a switching operation,
For each of the stacks, if it is determined that the voltage calculated for the stack is higher than the stack average voltage, the switching element in the transbalance circuit corresponding to the stack is not switched,
For each stack, if it is determined that the voltage calculated for the stack is equal to the stack average voltage, the equalization operation for the stack is terminated.
The battery equalizing apparatus according to claim 2. For each stack, the charge discharged from one or more of the battery cells in the stack is charged to one or more other battery cells of the stack. A converter balance circuit for equalizing the voltage of the battery cells in the stack;
The battery equalizing apparatus according to claim 1, wherein the battery equalizing apparatus is a battery equalizing apparatus. The converter balance circuit supplies power discharged from one or more of the battery cells in the stack to one of the battery cells in the stack via a circuit including a switching element and an inductor. Let the other battery cells charge,
The battery equalizing apparatus according to claim 4. A battery equalization method for equalizing voltages of a plurality of battery cells in an assembled battery configured by connecting a plurality of battery cells in series,
Among the plurality of battery cells, as the operation of equalizing the voltage between the stacks by discharging or charging the charge for each stack of a plurality of stacks composed of a predetermined number of battery cells, individually for each stack. Perform individual equalization operations via switching elements, transformers, and rectifier circuits connected to
Monitoring and detecting the voltage of each battery cell;
The voltage of the stack is calculated based on the detected voltage of each battery cell, the stack on which the equalization operation is to be performed is determined based on the calculated voltage, and the stack corresponds to the determined stack. Instructing a switching operation corresponding to the equalization operation to the switching element to execute the equalization operation;
The battery equalization method characterized by the above-mentioned. Both terminals of the assembled battery are connected to the primary winding of the transformer via the switching element corresponding to the transformer,
Connecting both terminals of the stack to the secondary winding of the transformer via the rectifier circuit;
The battery equalization method according to claim 6. Calculate the voltage of the entire assembled battery based on the voltage of each battery cell detected by the voltage monitoring unit, calculate the stack average voltage by dividing the voltage by the number of stacks in the assembled battery,
For each stack, if it is determined that the voltage calculated for the stack is lower than the stack average voltage, the switching element in the transbalance circuit corresponding to the stack is caused to perform a switching operation,
For each of the stacks, if it is determined that the voltage calculated for the stack is higher than the stack average voltage, the switching element in the transbalance circuit corresponding to the stack is not switched,
For each stack, if it is determined that the voltage calculated for the stack is equal to the stack average voltage, the equalization operation for the stack is terminated.
The battery equalization method according to claim 7.

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