JP7154201B2 - Cell balance controller - Google Patents

Description

The present invention relates to a cell balance control device.

Patent Document 1 below describes cell balance control that equalizes the cell voltages of a plurality of battery cells by alternately discharging odd-numbered and even-numbered battery cells among a plurality of battery cells connected in series. An implementing cell balancing controller is disclosed.
The cell balance control device is connected to wiring drawn out from both ends of each battery cell (hereinafter referred to as "cell voltage detection wiring"), and each cell voltage is detected via each cell voltage detection wiring. Monitor cell voltage.

Here, if disconnection occurs in the cell voltage detection wiring, an accurate cell voltage cannot be detected, making appropriate cell balance control difficult. Therefore, in Patent Document 1 below, among the adjacent battery cells, the cell voltage of one battery cell (hereinafter referred to as "first cell voltage") and the cell voltage of the other battery cell (hereinafter referred to as "second cell voltage") A technique is disclosed for detecting the presence or absence of disconnection of a cell voltage detection wiring based on the voltage difference between the cell voltage.

JP 2017-184494 A

Here, if the cell balance control is executed, the first cell voltage and the second cell voltage fluctuate, so it is impossible to reliably detect the presence or absence of disconnection of the cell voltage detection wiring.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cell balance control device that more reliably detects disconnection of cell voltage detection wiring than in the prior art.

(1) One aspect of the present invention consists of a series circuit of a bypass resistor and a switching element, a discharge circuit connected in parallel to each of a plurality of battery cells connected in series with each other, and a discharge circuit drawn out from both ends of each battery cell. a voltage detection circuit for detecting the voltage of each of the battery cells; a filter circuit connected to each of the wirings and having a capacitor and a resistor; Equalizing odd discharge that controls the odd switching element, which is a switching element of the discharge circuit connected in parallel to the th battery cell, to the ON state for a first time, and is connected in parallel to the even number battery cell. Cell balance control that equalizes the voltage of each battery cell by alternately performing equalizing even discharge that controls the even switching element, which is the switching element of the discharge circuit, to the ON state for a second time. a static elimination control unit that controls the even-numbered switching element to be ON for a third period of time shorter than the second period of time to perform static elimination control to remove the charge from the capacitor; and cells of adjacent battery cells. a disconnection detection unit that detects the presence or absence of disconnection of the wiring based on the voltage difference between the first cell voltage and the second cell voltage, wherein the disconnection detection unit detects the first cell voltage and the second cell voltage. A first diagnostic process is executed to determine whether there is a possibility of disconnection based on the cell voltage, and when it is determined that there is a possibility of disconnection as a result of the first diagnostic process, the cell balance control is stopped. and continuing the static elimination control, and after stopping the cell balance control, executing a second diagnostic process for determining whether or not there is a disconnection according to the voltage difference between the first cell voltage and the second cell voltage. It is a cell balance control device that

(2) In the cell balance control device according to (1) above, at least one of the plurality of wires drawn out from each battery cell is bifurcated into a first wire and a second wire. The filter circuit is connected to each of the first wiring and the second wiring, and the cell balance control is performed after the possibility of disconnection is detected in the first diagnostic processing. The equalizing odd discharge and the equalizing even discharge may be alternately performed a predetermined number of times and then stopped.

(3) In the cell balance control device of (2) above, when the first diagnosis process determines that there is a possibility of disconnection, the cell balance control unit performs the equalization odd discharge and The cell balance control may be stopped after the equalizing even discharge is performed once each.

As described above, according to the present invention, disconnection detection of the cell voltage detection wiring can be performed more reliably than in the conventional art.

1 is a schematic configuration diagram of a vehicle running system A including a cell balance control device according to this embodiment; FIG. It is a schematic block diagram of the cell balance control apparatus 6 which concerns on this embodiment. It is a figure explaining the operation mode of the switching element 20b which concerns on this embodiment. It is a figure explaining voltage difference (DELTA)V which concerns on this embodiment. FIG. 10 is a diagram showing an example of a timing chart for disconnection detection according to the present embodiment; It is a figure which shows the state which the wiring L3 which concerns on this embodiment disconnected. FIG. 10 is a diagram showing an example of a timing chart for disconnection detection according to the present embodiment;

Hereinafter, the cell balance control device according to this embodiment will be described using the drawings.

FIG. 1 is a schematic configuration diagram of a vehicle running system A including a cell balance control device according to this embodiment.

As shown in FIG. 1, a vehicle running system A includes an assembled battery 1, a first contactor 2, a second contactor 3, a motor 4, a power converter 5, a cell balance control device 6, and a battery ECU 7. there is

The assembled battery 1 is, for example, a battery mounted in the vehicle such as an electric vehicle or a hybrid vehicle, and is a secondary battery such as a lithium ion battery or a nickel metal hydride battery. Moreover, the assembled battery 1 may be an all-solid battery.

The assembled battery 1 includes a plurality of battery cells b1 to bn (n is an integer equal to or greater than 2) connected in series. That is, the assembled battery 1 is an assembled battery in which n battery cells b1 to bn are connected in series. In the assembled battery 1, the positive terminal of the battery cell b1 located at the highest level is the positive terminal T1 of the assembled battery 1, and the negative terminal of the battery cell bn located at the lowest level is the negative terminal T2 of the assembled battery 1. When the battery cells b1 to bn are not distinguished from each other, they are simply referred to as "battery cell b." In this embodiment, the case of n=4 will be described. However, the number of battery cells b connected to the cell balance control device 6 of the present embodiment is not particularly limited, and may be connected to a plurality of battery cells b connected in series.

The first contactor 2 is an energizing switch with a pair of contacts. The first contactor 2 has a first contact connected to the positive terminal T1 of the assembled battery 1 and a second contact connected to the first input terminal of the power converter 5 . The first contactor 2 is controlled to a closed state or an open state according to control from the battery ECU 7 . When the first contactor 2 is controlled to be closed, the positive terminal T1 of the assembled battery 1 and the first input end of the power converter 5 are electrically connected. When the first contactor 2 is controlled to be open, the electrical connection between the positive terminal T1 of the assembled battery 1 and the first input end of the power converter 5 is released.

The second contactor 3 is an energizing switch with a pair of contacts. The second contactor 3 has a first contact connected to the negative terminal T2 of the assembled battery 1 and a second contact connected to the second input end of the power converter 5 . The second contactor 3 is controlled to a closed state or an open state according to control from the battery ECU 7 . When the second contactor 3 is controlled to be closed, the minus terminal T2 of the assembled battery 1 and the second input end of the power converter 5 are electrically connected. When the second contactor 3 is controlled to be open, the electrical connection between the negative terminal T2 of the assembled battery 1 and the second input terminal of the power converter 5 is released.

The motor 4 generates driving power when power is supplied from the assembled battery 1 through the power converter 5 . Also, the motor 4 generates electric power through regenerative operation. Electric power generated by the regenerative operation of the motor 4 (hereinafter referred to as “regenerative electric power”) is supplied to the assembled battery 1 via the power converter 5 . For example, the motor 4 is a motor for running the vehicle.

The power converter 5 converts the DC power from the assembled battery 1 into a predetermined AC power and supplies it to the motor 4 . Further, when the motor 4 is in regenerative operation, the power converter 5 converts the regenerative power supplied from the motor 4 from AC to DC and supplies it to the assembled battery 1 . The power converter 5 comprises an inverter and may further comprise a DCDC converter.

The cell balance control device 6 is electrically connected to each of the battery cells b1 to bn via (n+1) wirings L1 to Ln+1. The cell balance control device 6 detects the terminal voltage (hereinafter referred to as “cell voltage”) V of each battery cell b1 to bn via (n+1) wires L1 to Ln+1, and equalizes each cell voltage V. Passive cell balance control is performed. The cell balance control device 6 outputs each detected cell voltage V to the battery ECU 7 . Note that when the wirings L1 to Ln+1 are not distinguished from each other, they are simply referred to as "wirings L".
Furthermore, the cell balance control device 6 has a disconnection detection function of detecting disconnection of the wiring L based on the voltage difference ΔV between the cell voltages V of the adjacent cell batteries b.

The wiring L is connected to the output terminals (positive terminal and negative terminal) of each battery cell b1 to bn. For example, the wiring L1 has a first end connected to the negative terminal of the battery cell b1 and a second end connected to the cell balance control device 6 . The wiring L2 has a first end connected to the positive terminal of the battery cell b1 (negative terminal of the battery cell b2) and a second end connected to the cell balance control device 6 . The wiring L3 has a first end connected to the positive terminal of the battery cell b2 (negative terminal of the battery cell b3) and a second end connected to the cell balance control device 6 . The wiring L4 has a first end connected to the positive terminal of the battery cell b3 (negative terminal of the battery cell b4) and a second end connected to the cell balance control device 6 . The wiring L5 has a first end connected to the positive terminal of the battery cell b4 (negative terminal of the battery cell b5) and a second end connected to the cell balance control device 6 . The wiring L6 has a first end connected to the positive terminal of the battery cell b5 and a second end connected to the cell balance control device 6 .

The battery ECU 7 controls the operation of the first contactor 2 and the second contactor 3 described above based on an operation instruction (for example, "ON" of the ignition switch) by the driver of the vehicle. Thereby, the battery ECU 7 can control discharging from the assembled battery 1 to the power converter 5 . In addition, the battery ECU 7 controls the operation of the first contactor 2 and the second contactor 3 to transfer regenerated power from the motor 4 and power from an external charger provided outside the vehicle to the assembled battery 1. can be charged. In addition to controlling the first contactor 2 and the second contactor 3, the battery ECU 7 notifies the cell balance control device 6 of the open/closed states of the first contactor 2 and the second contactor 3 based on the control. good too.
The battery ECU 7 does not charge the assembled battery 1 when even one of the plurality of cell voltages V acquired from the cell balance control device 6 reaches a voltage corresponding to full charge.

Next, the configuration of the cell balance control device 6 according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 2 is a schematic configuration diagram of the cell balance control device 6 according to this embodiment.

The cell balance control device 6 has a discharge section 10 and a control device 20 .
The discharge unit 10 is provided on the wiring L between the assembled battery 1 and the cell balance control device 6 .

An example of a specific configuration of the discharge section 10 will be described below with reference to FIG.

The discharge section 10 includes a plurality of discharge circuits 11 and a plurality of filter circuits 12 .

The discharge circuit 11 is connected in parallel with each battery cell b and can discharge the battery cell b. That is, the discharging unit 10 includes the same number of discharging circuits 11 as the plurality of battery cells b connected in series within the assembled battery 1 .

Specifically, the discharge circuit 11-1 is connected in parallel to the battery cell b1 by being connected between the wiring L1 and the wiring L2. The discharge circuit 11-1 can discharge the battery cell b1 under the control of the cell balance control device 6. FIG. The discharge circuit 11-2 is connected in parallel to the battery cell b2 by being connected between the wiring L2 and the wiring L3. The discharge circuit 11-2 can discharge the battery cell b2 under the control of the cell balance control device 6. FIG. The discharge circuit 11-3 is connected in parallel to the battery cell b3 by being connected between the wiring L3 and the wiring L4. The discharge circuit 11-3 can discharge the battery cell b3 under the control of the cell balance control device 6. FIG. The discharge circuit 11-4 is connected in parallel to the battery cell b4 by being connected between the wiring L4 and the wiring L5. The discharge circuit 11-4 can discharge the battery cell b4 under the control of the cell balance controller 6. FIG.

Note that the discharge circuits 11-1 to 11-4 have the same configuration. When the discharge circuits 11-1 to 11-4 are not distinguished from each other, they are simply referred to as "discharge circuit 11".
The discharge circuit 11 comprises a series circuit of one or more bypass resistors 20a and switching elements 20b. Each discharge circuit 11 is in a discharging state when the switching element 20b is turned on, and is in a non-discharging state when the switching element 20b is turned off.

The filter circuit 12 is a low-pass filter for removing noise provided on each of the n+1 lines L1 to Ln+1, and is composed of a filter resistor 12a and a filter capacitor 12b.

Here, in the example shown in FIG. 2, since five wirings L1 to L5 are connected to the control device 20, the filter circuit 12 is connected to each of the wirings L1 to L5. However, the wiring L3 is bifurcated into a first wiring La and a second wiring Lb from the middle, and the first wiring La and the second wiring Lb are each connected to the control device 20. . Therefore, the filter circuit 12 is provided for each of the first wiring La and the second wiring Lb.
In the example shown in FIG. 2, the filter circuit 12-1 is connected to the line L1, and the filter circuit 12-2 is connected to the line L2. Also, the filter circuit 12-3a is connected to the wiring La, and the filter circuit 12-3b is connected to the wiring Lb. Also, the filter circuit 12-4 is connected to the line L4, and the filter circuit 12-5 is connected to the line L5.

Next, the configuration of the control device 20 according to this embodiment will be described using FIG.
As shown in FIG. 2 , the control device 20 includes a voltage detection section 30 and a control section 40 .

The voltage detection unit 30 detects each cell voltage V of a plurality of battery cells connected in series. Specifically, the voltage detection unit 30 is electrically connected to each of the battery cells b1 to bn via (n+1) wirings L1 to Ln+1, and is electrically connected to each of the battery cells b1 to bn via (n+1) wirings L1 to Ln+1. Each cell voltage V of each battery cell b1 to bn is detected. Then, the voltage detection section 30 outputs each detected cell voltage V to the control section 40 . Note that the voltage detection unit 30 may be composed of one or a plurality of integrated circuits.

For example, the voltage detection unit 30 includes a plurality of cell voltage detection ICs 31, which are integrated circuits for detecting the cell voltage V. FIG. In this embodiment, the voltage detection unit 30 includes two cell voltage detection ICs 31a and 31b.

The cell voltage detection IC 31a is connected to the wiring L1, the wiring L2 and the wiring Lb. The cell voltage detection IC 31a detects the difference between the voltage of the wiring L1 and the voltage of the wiring L2 as the cell voltage V1 of the battery cell b1. The cell voltage detection IC 31a detects the difference between the voltage of the wiring L2 and the voltage of the wiring Lb as the cell voltage V2 of the battery cell b2. The cell voltage detection IC 31 a outputs the detected cell voltage V<b>1 and cell voltage V<b>2 to the controller 40 .
The cell voltage detection IC 31b is connected to the wiring La, the wiring L4 and the wiring L5. The cell voltage detection IC 31b detects the difference between the voltage of the line La and the voltage of the line L4 as the cell voltage V3 of the battery cell b3. The cell voltage detection IC 31b detects the difference between the voltage of the wiring L4 and the voltage of the wiring L5 as the cell voltage V4 of the battery cell b4. The cell voltage detection IC 31 b outputs the detected cell voltage V 3 and cell voltage V 4 to the control section 40 .

The control unit 40 includes a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit) and nonvolatile or volatile semiconductor memory (e.g., RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory)) may be provided. For example, the control unit 40 may be a microcontroller such as an MCU.

The functional configuration of the control unit 40 according to this embodiment will be described below with reference to FIG. 2 . The control unit 40 according to this embodiment includes a cell balance control unit 41 , a static elimination control unit 42 and a disconnection detection unit 43 .

The cell balance control unit 41 performs cell balance control by controlling the ON state and OFF state of each switching element 20 b of the plurality of discharge circuits 11 . Specifically, the cell balance control unit 41 switches the odd-numbered switching element, which is the switching element 20b of the discharge circuit 11 connected in parallel to the odd-numbered battery cell b among the plurality of battery cells b, to the first time period. The equalizing odd discharge is controlled to be ON for T1, and the even switching element, which is the switching element 20b of the discharge circuit 11 connected in parallel to the even-numbered battery cell b, is controlled to be ON for the second time T2. Cell balance control is performed to equalize the cell voltage of each battery cell b by alternately performing equalized even discharge. Here, the odd-numbered battery cell b means the odd-numbered battery cell b that is counted from the positive terminal T1 or the negative terminal T2 among the plurality of battery cells b connected in series between the positive terminal T1 and the negative terminal T2. battery cell b. An even-numbered battery cell b is a battery arranged in an even-numbered order counting from the positive terminal T1 or the negative terminal T2 among a plurality of battery cells b connected in series between the positive terminal T1 and the negative terminal T2. cell b. In this embodiment, the odd-numbered battery cells b are the battery cell b1 and the battery cell b3, and the even-numbered battery cells b are the battery cell b2 and the battery cell b4.

Therefore, the cell balance control unit 41 performs equalized odd discharge by turning on only the switching elements 20b of the discharge circuits 11-1 and 11-3 as odd switching elements. The cell balance control unit 41 performs equalized even discharge by turning on only the switching elements 20b of the discharge circuits 11-2 and 11-4 as even switching elements. Note that the first time T1 and the second time T2 may be the same or different. For example, the first time T1 and the second time T2 are each about several tens of ms.

The static elimination control unit 42 performs static elimination control to remove the charge from the filter capacitor 12b by controlling the even-numbered switching element to be ON for a third time T3 shorter than the second time. For example, the third time T3 is several hundred μs. The static elimination control and the equalizing even discharge differ only in the time for controlling the even switching elements to the ON state, and the switching element 20b to be controlled to the ON state is the same. This static elimination control turns on only the even-numbered switching elements, so that when a disconnection occurs in the wiring L, the static elimination control is performed by the odd-numbered switching elements and the even-numbered switching elements rather than by performing the static elimination control on the adjacent battery cells. Since the potential difference ΔV of the cell voltage spreads quickly, it is possible to shorten the time until disconnection detection is performed. As shown in FIG. 3, the operation mode of the switching element 20b is repeated in order of static elimination control, equalizing odd discharge, static elimination control, and equalizing even discharge. Note that, as shown in FIG. 3, the control device 202 may acquire each cell voltage detected by the voltage detection unit 30 immediately before performing static elimination control.

The disconnection detection unit 43 executes disconnection detection processing for detecting whether or not the wiring L is disconnected based on the voltage difference ΔV between the cell voltages V of the pair of adjacent battery cells b. In the disconnection detection process, when a disconnection occurs in the wiring L, the cell voltage of one of the two battery cells b connected to the wiring L (hereinafter referred to as “first cell voltage”) and the , the voltage difference .DELTA.V between the cell voltages of the other battery cell b (hereinafter referred to as "second cell voltage") gradually increases.

The voltage difference ΔV according to this embodiment will be described below with reference to FIG. 4 .

For example, as shown in FIG. 4A, it is assumed that the battery cell bx is the even-numbered battery cell and the battery cell bx+1 is the odd-numbered battery cell. The battery cell bx and the battery cell bx+1 correspond to adjacent battery cells b. The disconnection detection process is executed when the even switching elements are in the ON state and the odd switching elements are in the OFF state. That is, in the example shown in FIG. 4, the switching element of the discharge circuit 11-x connected in parallel to the battery cell bx is an even switching element, and the switching element of the discharge circuit 11-(x+1) connected in parallel to the battery cell bx+1. The switching elements are odd switching elements.

Here, as shown in FIG. 4A, it is assumed that a wire Lx+1 drawn from a connection point between the battery cell bx and the battery cell bx+1 is disconnected. In this case, two cell voltages of the battery cell bx and the battery cell bx+1 are input to the control device 20 as the cell voltage Vx+1 (first cell voltage), and the charge of the filter capacitor 12b connected to the line Lx+1 is The charges are removed toward the filter capacitor 12b connected to the line Lx via the discharge circuit 11-x. As a result, as shown in FIG. 4B, the cell voltage Vx+1 (first cell voltage) gradually rises, and cell voltage Vx (second cell voltage ) gradually decreases. As a result, when the wire Lx+1 is disconnected, the voltage difference ΔV (=|Vx+1−Vx|) gradually increases.
Therefore, the disconnection detection unit 43 detects the disconnection of the wiring L by utilizing the phenomenon that the voltage difference ΔV due to the disconnection of the wiring L gradually increases.

However, if the cell balance control is continuously performed, the equalizing even discharge and the equalizing odd discharge are alternately executed, so the equalizing odd discharge is executed after the disconnection occurs. As a result, as shown in FIG. 4B, the cell voltage Vx+1 (first cell voltage) gradually decreases and the cell voltage Vx (second cell voltage) gradually increases. In this way, when the equalized even discharge and the equalized odd discharge are alternately executed in a state where disconnection occurs, the cell voltage Vx+1 (first cell voltage) and the cell voltage Vx (second cell voltage) are increased. fluctuate. That is, when the equalized even discharge is executed in the state where the disconnection occurs, the cell voltage Vx+1 (first cell voltage) gradually increases and the cell voltage Vx (second cell voltage) gradually decreases. When a state occurs and an equalized odd discharge is performed, a second fluctuation state occurs in which the cell voltage (first cell voltage) Vx+1 gradually decreases and the cell voltage Vx (second cell voltage) gradually increases.

Therefore, in order to reliably detect the presence or absence of a wire breakage in the wire breakage detection process, the wire breakage detection unit 43 detects that the first cell voltage and the second cell voltage are not in a state in which the first cell voltage and the second cell voltage fluctuate. Disconnection is detected based on the voltage difference ΔV in a stable state without fluctuation.
Specifically, first, the disconnection detection unit 43 first diagnoses the possibility of disconnection based on the first cell voltage and the second cell voltage during or after the even discharge of the switching element 20b. Execute the process. The even discharge of the switching element 20b is either or both of static elimination control and equalizing even discharge. However, it is not limited to this, and the disconnection detection unit 43 only needs to execute the first diagnostic process every constant cycle (first cycle) regardless of the even discharge. When the disconnection detection unit 43 determines that there is a possibility of disconnection as a result of the first diagnosis process, the disconnection detection unit 43 stops the cell balance control and continues the static elimination control. After the cell balance control is stopped, the disconnection detection unit 43 executes a second diagnostic process for determining the presence or absence of disconnection according to the voltage difference ΔV between the first cell voltage and the second cell voltage. For example, the first diagnostic process is executed in a first period, and the second diagnostic process is executed in a second period shorter than the first period.

For example, in the first diagnostic process, the cell voltage Vx+1 (first cell voltage) is compared with a threshold value Vth1, and the cell voltage Vx (second cell voltage) is compared with a threshold value Vth2 to determine the possibility of disconnection. It is a process to That is, the disconnection detection unit 43 executes the first diagnostic process every first cycle, the cell voltage Vx+1 (first cell voltage) exceeds the threshold Vth1, and the cell voltage Vx (second cell voltage) exceeds the threshold Vth2. , it is determined that there is a possibility of disconnection. However, the disconnection detection unit 43 is not limited to this, and the disconnection detection unit 43 executes the first diagnosis process every first period, and when the cell voltage Vx+1 (first cell voltage) exceeds the threshold Vth1 and when the cell voltage Vx (second cell voltage) is lower than the threshold value Vth2, it may be determined that there is a possibility of disconnection. However, the first diagnosis process is not limited to this, and the process of determining the possibility of disconnection when the voltage difference ΔV between the first cell voltage and the second cell voltage exceeds the threshold value Vx. good. Note that the threshold value Vx may be the same value as the threshold value Δth, which will be described later, or may be a different value.

When the disconnection detection unit 43 determines that there is a possibility of disconnection, the disconnection detection unit 43 outputs a stop command signal for stopping the cell balance control to the cell balance control unit 41, thereby stopping the cell balance control. Then, the disconnection detection unit 43 executes the second diagnosis process after stopping the cell balance control, and the voltage difference ΔV between the cell voltage Vx+1 (first cell voltage) and the cell voltage Vx (second cell voltage) is equal to or greater than the threshold Δth. If it is determined that the voltage difference ΔV is greater than or equal to the threshold value Δth, it is determined that a disconnection has occurred.

Here, in FIG. 4B, when the disconnection detection unit 43 determines that there is a possibility of disconnection in the first diagnostic process and stops the cell balance control, it is possible to immediately stop the cell balance control. If possible, the odd equalization shown in FIG. 4(b) is not performed. However, the first diagnostic process is executed in the first period, and the timing at which the cell voltage Vx+1 (first cell voltage) exceeds the threshold Vth1 and the cell voltage Vx (second cell voltage) falls below the threshold Vth2. It is not always determined that there is a possibility of disconnection at time Tx, but it is determined that there is a possibility of disconnection in a time period after Tx. Therefore, depending on the timing of the first diagnostic process, the equalized odd discharge may start before the cell balance control unit 41 receives the stop command signal. Furthermore, due to the communication relationship between the disconnection detection unit 43 and the cell balance control unit 41, it takes a predetermined time from when the disconnection detection unit 43 outputs the stop command signal to when the cell balance control unit 41 receives the stop command signal. It takes time. Therefore, the cell balance control unit 41 may execute the equalization odd discharge only once before receiving the stop command signal.

Specifically, as shown in FIG. 5A, when a wire breakage occurs at time t1, the wire breakage detection unit 43 detects possible wire breakage by the first diagnostic process between time t2 and time t3. and output a stop command signal. However, since the time t3 at which the equalized odd discharge starts before the cell balance control unit 41 receives the stop command signal, the cell balance control unit 41 executes the equalized odd discharge. As a result, the first cell voltage gradually drops and the second cell voltage gradually rises. Since the cell balance control is stopped when the equalizing odd discharge ends, only the static elimination control is continued in the time zone after the time t4. In this static elimination control, the even-numbered switching elements are controlled to be in the ON state, so that the first cell voltage gradually rises, the second cell voltage 2 Cell voltage stabilizes. Therefore, the disconnection detection unit 43 performs the disconnection detection reliably by executing the second diagnostic process from the time t5 when a certain period of time has elapsed since the disconnection detection unit 43 determined that there is a possibility of disconnection in the first diagnostic process. can be done.

The example shown in FIG. 5A is a case where the wiring L, which is not bifurcated among the wirings L1 to L5, is broken. That is, in the present embodiment, the wiring L other than the wiring L3 among the wirings L1 to L5 is disconnected.
When the line L3 is disconnected, a wraparound phenomenon occurs in which charges move from the filter capacitor 12b of the filter circuit 12-3a to the filter capacitor 12b of the filter circuit 12-3b along the wraparound route R1 shown in FIG. Therefore, when the wiring L3 is disconnected, as shown in FIG. 5B, the time from time t4 until the first cell voltage and the second cell voltage are stabilized is that the wiring L other than the wiring L3 is disconnected. It is longer than the case (FIG. 5(a)). Therefore, in the example shown in FIG. 5(b), the time required to detect disconnection is longer than in FIG. 5(a).

Therefore, the cell balance control unit 41 according to the present embodiment, in the case where the wiring L3 branching into two is broken, the first When it is determined in the diagnostic process that there is a possibility of disconnection, the equalization odd discharge and the equalization even discharge may be performed once each in order, and then the cell balance control may be stopped.
That is, even if the cell balance control unit 41 receives the stop command signal, it executes the equalized even discharge only once from the time t4 shown in FIG. 5(b). In the equalized even discharge, the ON state of the even switching element is longer than in the static elimination control, so the charge in the filter capacitor 12b of the filter circuit 12-3b can be discharged by the static elimination route R2 shown in FIG. As a result, the time from time t4 to the stabilization of the cell voltage V3, which is the first cell voltage, and the cell voltage V2, which is the second cell voltage, can be shortened.
In this way, when the plurality of wirings L connecting the battery cells b and the cell balance control device 6 include wirings that branch into two branches, the cell balance control detects the possibility of disconnection in the first diagnostic process. After that, the equalizing odd discharge and the equalizing even discharge are alternately performed a predetermined number of times (once in this embodiment) and then stopped. After the cell balance control is stopped, the disconnection detection unit 43 executes a second diagnostic process for determining whether or not there is a disconnection according to the voltage difference ΔV.

Next, an example of disconnection detection processing in the cell balance control device 6 according to this embodiment will be described with reference to FIG. FIG. 7 is a timing chart of disconnection detection processing in the cell balance control device 6 according to this embodiment.

As shown in FIG. 7, it is assumed that the line L3 is disconnected at time t1. At this time, since the cell balance control unit 41 is executing equalized even discharge, the switching elements 20b of the discharge circuits 11-2 and 11-4 are on. Therefore, of the battery cells b2 and b3 adjacent to each other, the cell voltage V2 of the battery cell b2 decreases and the cell voltage V3 of the battery cell b3 increases.
In the first diagnostic process after time t2, the disconnection detection unit 43 determines that the cell voltage V2 has fallen below the threshold Vth2 and the cell voltage V3 has exceeded the threshold Vth1, and that there is a possibility of disconnection. The disconnection detection unit 43 outputs a stop command signal to the cell balance control unit 41 when determining that there is a possibility of disconnection. If the cell balance control unit 41 does not receive the stop command signal by time t3, the equalization odd discharge is performed. As a result, the cell voltage V2 of the battery cell b2 increases and the cell voltage V3 of the battery cell b3 decreases.

Here, the cell balance control unit 41 receives the stop command signal from time t3 to time t4. That is, the cycle of cell balance control and the cycle (first cycle) of the first diagnostic process are set in advance so that the stop command signal can be received from time t3 to time t4. Therefore, when the stop command signal is received, the cell balance control unit 41 executes the equalized even discharge only once after the equalized odd discharge, and stops the cell balance control. As a result, the equalized even discharge is executed from time t4, and the charge of the filter capacitor 12b of the filter circuit 12-3b is discharged in the static elimination route R2 in a longer time than during the static elimination control. As a result, the cell voltage V2 and the cell voltage V3 are stabilized in a short time. The disconnection detection unit 43 executes the second diagnosis process from time t5. The timing for starting the second diagnostic process by the disconnection detection unit 43 is set in advance. For example, the disconnection detection unit 43 may start the second diagnostic process when a predetermined period of time has elapsed since it was determined in the first diagnostic process that there is a possibility of disconnection.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design and the like are included within the scope of the gist of the present invention.

(Modification) In the equalized even discharge, the cell balance control device 6 of the above embodiment turns ON/OFF the odd switching elements at a duty ratio of 4%, for example, and turns the even switching elements at a duty ratio of 96%, for example. It may be turned ON/OFF by the tee ratio. In the equalized odd discharge, the cell balance controller 6 turns on/off the odd switching elements with a duty ratio of 96%, for example, and turns the even switching elements on/off with a duty ratio of 4%, for example. You may let

As described above, the cell balance control device 6 according to the above embodiment has the disconnection detector 43 that detects disconnection of the wiring L. FIG. Then, the disconnection detection unit 43 executes a first diagnostic process for determining the possibility of disconnection based on the first cell voltage and the second cell voltage, which are the cell voltages of adjacent battery cells. As a result, when it is determined that there is a possibility of disconnection, the cell balance control is stopped and the static elimination control is continued, and after the cell balance control is stopped, the voltage difference ΔV between the first cell voltage and the second cell voltage Accordingly, a second diagnostic process for determining whether or not there is a disconnection is executed.

According to such a configuration, the second diagnostic process can be executed in a state where the first cell voltage and the second cell voltage are stable without fluctuation, and disconnection detection of the wiring L can be performed more reliably than before. It can be carried out.

Further, in the cell balance control device 6, at least one of the plurality of wirings L drawn from each battery cell (the wiring L3 in this embodiment) is bifurcated into the first wiring and the second wiring. may be divided into In this case, the filter circuit 12 is connected to each of the first wiring and the second wiring, and the cell balance control is performed after the possibility of disconnection is detected in the first diagnostic process. The odd-numbered discharge and the equalized even-numbered discharge are alternately performed a predetermined number of times and then stopped.

According to such a configuration, it is possible to shorten the time until the disconnection is detected when the bifurcated wiring L3 divided into the first wiring and the second wiring is disconnected in the middle of the wiring.

All or part of the control device 20 described above may be realized by a computer. In this case, the computer may comprise a processor such as a CPU or GPU and a computer-readable recording medium. A program for realizing all or part of the functions of the control device 20 by a computer is recorded in the computer-readable recording medium, and the program recorded in the recording medium is read into the processor. It may be realized by setting and executing Here, "computer-readable recording media" means portable media such as flexible discs, magneto-optical discs, ROMs, and CD-ROMs, and storage devices such as hard discs built into computer systems. Say things. Furthermore, "computer-readable recording medium" means a medium that can be moved for a short period of time, such as a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include a memory that holds the program temporarily, or a memory that holds the program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in that case. Further, the above program may be for realizing a part of the functions described above, or may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. , FPGA, or other programmable logic device.

L wiring 6 cell balance control device 10 discharge unit 11 discharge circuit 12 filter circuit 20 control device 30 voltage detection unit 40 control unit 41 cell balance control unit 42 static elimination control unit 43 disconnection detection unit

Claims (3)

a discharge circuit comprising a series circuit of a bypass resistor and a switching element and connected in parallel to each of the plurality of battery cells connected in series;
a voltage detection circuit electrically connected by wiring drawn out from both ends of each battery cell and detecting a voltage of each battery cell;
a filter circuit connected to each wiring and having a capacitor and a resistor;
Equalizing odd discharge for controlling the odd-numbered switching element, which is the switching element of the discharge circuit connected in parallel to the odd-numbered battery cells among the plurality of battery cells, to be ON for a first period of time; The voltage of each battery cell is made uniform by alternately executing the equalizing even-numbered discharge, in which the even-numbered switching element, which is the switching element of the discharge circuit connected in parallel to the battery cells, is controlled to be ON for a second period of time. a cell balance control unit that performs cell balance control;
a static elimination control unit that controls the even-numbered switching element to be ON for a third period of time shorter than the second period of time to perform static elimination control to remove the charge of the capacitor;
a disconnection detection unit that detects the presence or absence of disconnection of the wiring based on a voltage difference between a first cell voltage and a second cell voltage, which are cell voltages of adjacent battery cells;
with
The disconnection detection unit executes a first diagnostic process for determining whether there is a possibility of disconnection based on the first cell voltage and the second cell voltage. If it is determined that there is, the cell balance control is stopped and the static elimination control is continued, and after the cell balance control is stopped, disconnection according to the voltage difference between the first cell voltage and the second cell voltage A cell balance control device characterized by executing a second diagnostic process for determining the presence or absence of. At least one of the plurality of wirings drawn out from each battery cell is bifurcated into a first wiring and a second wiring,
The filter circuit is connected to each of the first wiring and the second wiring,
The cell balance control is stopped after the equalized odd discharge and the equalized even discharge are alternately performed a predetermined number of times in order after the possibility of disconnection is detected in the first diagnostic process.
The cell balance control device according to claim 1, characterized by: When it is determined in the first diagnosis process that there is a possibility of disconnection, the cell balance control unit executes the equalization odd discharge and the equalization even discharge once in order, and then stop cell balance control,
characterized by
The cell balance control device according to claim 2.

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