JP7528451B2 - On-board battery control device - Google Patents

Description

This disclosure relates to an on-board battery control device.

Conventionally, an example of an on-board battery control device that controls a battery pack is a battery pack monitoring system (Patent Document 1).

The battery pack monitoring system includes a voltage monitoring device that monitors the voltage of each battery cell in the battery pack, a discharge resistor element and an RC filter that are connected between each battery cell and the voltage monitoring device, and a discharge switch that discharges the corresponding battery cell.

The voltage monitoring device is provided with three or more connection terminals corresponding to one battery cell. Two of the connection terminals are used to monitor the voltage of the battery cell via the output terminal of the RC filter. The remaining one or more connection terminals are used to form a discharge path for the battery cell when the discharge switch is turned on. In the battery pack monitoring system, the discharge resistance element is positioned in the discharge path so as not to discharge the charge in the capacitor that constitutes the RC filter. The control device also controls the on/off of the discharge switch to perform voltage equalization processing for each battery cell.

JP 2017-112677 A

Recently, vehicles are equipped with many ECUs. For this reason, there is a demand to reduce the current consumption of the auxiliary battery that supplies power to each ECU.

In addition, in Patent Document 1, when adjacent charge/discharge switches are both turned on, the current value increases because the current of the adjacent RC filters flows, which may lead to heat generation or malfunction of the voltage monitoring device, which corresponds to the ECU. For this reason, in Patent Document 1, in order to perform voltage equalization, it becomes necessary to start the voltage monitoring device and switch between the odd and even switches. Therefore, Patent Document 1 has the problem that the current consumption increases because the number of times the voltage monitoring device is started increases.

This disclosure was made in consideration of the above problems, and aims to provide an on-board battery control device that can suppress increases in current consumption.

In order to achieve the above object, the present disclosure provides:
An on-board battery control device that controls a battery pack (20) including a plurality of battery cells (201-20n) including a plurality of even-numbered cells and a plurality of odd-numbered cells,
A plurality of monitoring ICs (21 to 2n) that are connected to the assembled battery and receive power, include a plurality of equalization switches (111 to 113) connected in series, and perform voltage equalization of a plurality of battery cells;
The vehicle is equipped with a microcomputer (1) that is powered by an auxiliary battery (30) and issues control instructions to a plurality of monitoring ICs,
The monitoring IC is
The equalization switches include a plurality of even number switches provided corresponding to the even number cells and a plurality of odd number switches provided corresponding to the odd number cells,
When an equalization instruction is issued from the microcontroller, while the microcontroller is not started, the on/off control objects are switched between even switches and odd switches at predetermined time intervals based on the count value to perform voltage equalization.The count value is the counted value of the clock signal generated by the oscillator, and the interval at which the on/off control objects are switched between the even switches and odd switches is set in advance based on the accuracy of the oscillator .

In this way, the present disclosure allows the monitoring IC to switch the on/off control targets between the even switches and the odd switches, and perform voltage equalization, even when the microcontroller is not running. Therefore, the present disclosure can reduce the number of times the microcontroller is started up for voltage equalization, and can reduce the current consumption of the auxiliary battery.

The claims and the symbols in parentheses in this section indicate the correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of this disclosure.

2 is a block diagram showing a schematic configuration of a battery ECU according to the embodiment; FIG. 1 is a block diagram showing a schematic configuration of a monitoring IC according to an embodiment. 4 is a diagram showing a current flow in the embodiment. 4 is a flowchart showing a processing operation of a microcomputer in the embodiment. 5 is a flowchart showing a processing operation of a monitoring IC in the embodiment. 4 is a time chart showing a processing operation of a monitoring IC in the embodiment.

An embodiment of the present disclosure will be described with reference to Figures 1 to 6. In this embodiment, an example is used in which an on-board battery control device is applied to a battery ECU (Electronic Control Unit) 10.

First, the configuration of the battery ECU 10 will be described with reference to Figures 1, 2, and 3. The battery ECU 10 controls the main battery 20, which has multiple battery cells 201-20n, including multiple even-numbered cells and multiple odd-numbered cells. The main battery 20 corresponds to a battery pack.

The battery ECU 10 includes a microcomputer 1 and a first monitoring IC 21 to an n-th monitoring IC 2n. The battery ECU 10 also includes a printed circuit board 31 on which a filter 4 and a discharge resistor 5 are provided. The battery ECU 10 is also electrically connected to the main battery 20 and the auxiliary battery 30. In this embodiment, as an example, a battery ECU 10 is used in which the microcomputer 1, the multiple monitoring ICs 21 to 2n, and the printed circuit board 31 are configured as an integrated board. However, the present disclosure is not limited to this and can also be used with a battery ECU 10 on a satellite board. Here, n is a natural number equal to or greater than 2.

The battery ECU 10 is configured so that it can be mounted on vehicles such as hybrid vehicles, plug-in hybrid vehicles, and electric vehicles. The main battery 20 has multiple battery cells 201-20n, such as lithium secondary batteries and nickel-hydrogen secondary batteries, connected in series. The multiple battery cells 201-20n are connected in series from the low potential ground to the high potential side.

As an example, the main battery 20 is a battery consisting of multiple battery blocks connected in series. Each battery block includes multiple battery cells connected in series. One battery block includes, for example, a first battery cell 201, a second battery cell 202, a third battery cell 203, a fourth battery cell 204, and a first battery cell 205.

Each battery block is electrically connected to a different monitoring IC 21-2n. For example, the battery block including battery cells 201-205 is electrically connected to the first monitoring IC 21. And the battery block including the nth battery cell is electrically connected to the nth monitoring IC 2n.

The main battery 20 also has a plurality of battery cells 201-20n, including a plurality of even-numbered cells 20E (E: even number) and a plurality of odd-numbered cells 20O (O: odd number). Counting from the most upstream or most downstream, the even-numbered battery cells of the plurality of battery cells 201-20n are the even-numbered cells 20E, and the odd-numbered battery cells are the odd-numbered cells 20O.

For example, battery cells 201 to 205 are electrically connected to the first monitoring IC 21. That is, the first monitoring IC 21 is connected to the first battery cell 201, the third battery cell 203, and the fifth battery cell 205 as odd-numbered cells, and the second battery cell 202 and the fourth battery cell 204 as even-numbered cells. Similarly, the nth battery cell is electrically connected to the nth monitoring IC 2n. The number of battery cells connected to each of the monitoring ICs 21 to 2n is not limited to this.

The main battery 20 can be referred to as a battery pack. The battery cells 201 to 20n are each configured in the same way.

The auxiliary battery 30 has a lower terminal voltage than the main battery 20. The auxiliary battery 30 is electrically connected to low-voltage circuits such as the microcomputer 1. The auxiliary battery 30 supplies power to the low-voltage circuits such as the microcomputer 1.

The microcomputer 1 receives power from the auxiliary battery 30 and issues control instructions to the multiple monitoring ICs 21 to 2n. In other words, the microcomputer 1 operates by receiving power from the auxiliary battery 30. The microcomputer 1 includes, for example, a CPU, a storage device, and a communication circuit. The storage device includes a volatile memory such as an SRAM, and a non-volatile memory such as a flash memory or an EEPROM.

The microcomputer 1 is also electrically connected to each of the monitoring ICs 21 to 2n. In the microcomputer 1, the CPU executes a program stored in the non-volatile memory. By executing the program, the microcomputer 1 uses the volatile memory as a temporary storage unit and performs calculations using data stored in the storage device. In this way, the microcomputer 1 performs processing operations that will be described later. Note that the storage device stores data such as cell voltage values transmitted from the monitoring ICs 21 to 2n, for example.

The microcomputer 1 is configured to be able to communicate with each of the monitoring ICs 21-2n. The microcomputer 1 issues control instructions to each of the monitoring ICs 21-2n by sending commands to each of the monitoring ICs 21-2n. The microcomputer 1 also receives data indicating the cell voltage values sent from each of the monitoring ICs 21-2n.

The commands may be, for example, a start command to start voltage equalization, a stop command to stop voltage equalization, or a detection command to detect (measure) cell voltages and transmit the detection results. Furthermore, the commands may be diagnostic commands to diagnose whether or not there is a fault in the circuits in each of the monitoring ICs 21-2. The detection command may also include an instruction for AD conversion. The start command corresponds to an equalization instruction. Therefore, when the monitoring ICs 21-2n receive the start command, they consider that an equalization instruction has been issued.

The multiple monitoring ICs 21-2n are connected to the main battery 20 and receive power, include multiple equalization switches 111-113 connected in series, and mainly perform voltage equalization of the multiple battery cells 201-20n. Each of the multiple monitoring ICs 21-2n has a similar configuration and performs similar processing operations. For this reason, the following description will focus on the first monitoring IC 21 as a representative example.

As shown in FIG. 2, the first monitoring IC 21 includes a cell equalization circuit 110, an AD converter 120, a reference power supply 130, a logic circuit 140, a detection control unit 141, a communication control unit 142, an AD detection correction unit 143, an oscillator 150, a memory 160, and a communication I/F 170.

The first monitoring IC 21 has multiple pairs of connection terminals. One battery cell is connected to each pair of connection terminals of the first monitoring IC 21. The first monitoring IC 21 is configured to be able to detect the cell voltage of each of the battery cells 201 to 205.

As shown in Figures 2 and 3, the cell equalization circuit 110 includes a multiplexer (MUX) in addition to equalization switches 111 to 113 for equalizing the voltages of the battery cells. In this embodiment, the cell equalization circuit 110 includes a multiplexer. However, in the present disclosure, the multiplexer and the cell equalization circuit 110 may be provided separately.

In the following, when there is no need to distinguish between the equalization switches 111 to 113, they will be referred to simply as equalization switches without reference numbers. Also, each of the equalization switches 111 to 113 can be called a discharge switch because it discharges the corresponding battery cell 201 to 20n when it is turned on.

The cell equalization circuit 110 is electrically connected to a plurality of battery cells 201-205 via connection terminals. More specifically, the cell equalization circuit 110 is electrically connected to a plurality of battery cells 201-205 via a printed circuit board 31. The connection terminals can also be referred to as cell voltage detection terminals.

As shown in FIG. 3, the printed circuit board 31 includes a filter 4 and a discharge resistor 5. The filter 4 and the discharge resistor 5 are provided between the corresponding equalization switch and the battery cell. The corresponding equalization switch and battery cell are, for example, the first equalization switch 111 and the first battery cell 201. The filter 4 includes a resistive element 41 and a capacitor 42. Therefore, it can be said that the first monitoring IC 21 is electrically connected to the battery cells 201 to 205 via the filter 4 and the discharge resistor 5.

As shown in FIG. 3, the printed circuit board 31 connects the capacitor 42 to the rear connection point a2, which is the rear stage of the discharge resistor 5, rather than to the first connection point a1, which is the front stage of the discharge resistor 5. The monitoring IC 21 also connects the equalization switches 111 to 113 to the second connection point b2, which is the front stage of the discharge resistor 5, rather than to the intermediate connection b1 between the resistive element 41 and the capacitor 42.

In the present disclosure, by using such connection points a2 and b2, the terminal voltage of the cell voltage detection terminal is restored the moment the equalization switch 111 is turned off, and it is possible to immediately move on to the next process. In other words, in the present disclosure, when the equalization switch 111 is turned on and off to perform a fault diagnosis of the monitoring IC 21, it is not necessary to wait for the recovery time determined by the RC time constant of the filter 4, and the processing time can be shortened.

The cell equalization circuit 110 is provided with an equalization switch corresponding to each of the multiple battery cells 201 to 205. The multiple equalization switches include multiple even switches 11E provided corresponding to each even cell 20E, and multiple odd switches 11O provided corresponding to each odd cell 20O.

Here, as an example, only the first equalization switch 111, the second equalization switch 111, and the third equalization switch 113 are illustrated. However, for example, the first monitoring IC 21 is electrically connected to the battery cells 201 to 205. Therefore, the cell equalization circuit 110 of the first monitoring IC 21 is provided with five equalization switches corresponding to each of the battery cells 201 to 205. In other words, each monitoring IC 21 to 2n is provided with an equalization switch corresponding to each of the battery cells electrically connected to it.

The first equalization switch 111 is provided corresponding to the first battery cell 201. The second equalization switch 111 is provided corresponding to the second battery cell 202. The third equalization switch 113 is provided corresponding to the third battery cell 203.

In a vehicle equipped with a main battery 20, it is necessary to keep the cell voltages equal in order to make the most of regenerative energy. To achieve this, the first monitoring IC 21 is provided with a cell equalization circuit 110 as a function of equalizing the cell voltages. The first monitoring IC 21 periodically starts up while the vehicle's ignition switch is off to equalize the cell voltages. Cell voltage equalization corresponds to voltage equalization. In addition, in order to perform voltage equalization, it is desirable for the battery ECU 10 to diagnose whether or not there is a circuit failure in the first monitoring IC 21 by turning the equalization switch on and off.

The first monitoring IC 21 performs voltage equalization by turning on and off each of the equalization switches 111 to 113. Each of the equalization switches 111 to 113 is turned on and off according to an instruction from the detection control unit 141 of the logic circuit 140.

The cell equalization circuit 110 can discharge the first battery cell 201, for example, by turning on the first equalization switch 111 in response to an instruction from the detection control unit 141. Therefore, the first monitoring IC 21 can equalize the cell voltages of the battery cells 201 to 205 by discharging the battery cell with the higher cell voltage among the battery cells 201 to 205. As shown in FIG. 3, when the first equalization switch 111 is turned on, the battery ECU 10 causes an equalization current to flow as shown by the two-dot chain line, and the charge of the capacitor 42 of the filter 4 is discharged, causing a current to flow as shown by the dashed dot line.

The multiplexer is composed of multiple switch circuits, and selects one of the multiple sets of connection terminals in response to an instruction from the detection control unit 141 of the logic circuit 140. By selecting one set, the multiplexer electrically connects one of the battery cells 201-205. The multiplexer also includes a voltage detection unit that detects the cell voltage of the connected battery cell. The first monitoring IC 21 also connects the battery cells 201-205 to the multiplexer in sequence, and detects the cell voltage of each of the battery cells 201-205 in sequence.

The AD converter 120 is connected to a reference power supply 130. The AD converter 120 performs AD conversion based on the reference voltage generated by the reference power supply 130. The AD converter 120 also performs AD conversion on each cell voltage detected by the multiplexer in response to an instruction from the detection control unit 141. The AD converter 120 then outputs the AD conversion result to the logic circuit 140. Note that in FIG. 2, the AD converter 120 is abbreviated as ADC.

The logic circuit 140 includes, as functional blocks, a detection control unit 141, a communication control unit 142, and an AD detection correction unit 143. The logic circuit 140 is electrically connected to the oscillator 150, the memory 160, and the communication I/F 170.

The logic circuit 140 receives a clock signal generated by the oscillator 150. The oscillator 150 can be a ceramic oscillator or a crystal oscillator circuit including a crystal resonator. The logic circuit 140 is configured to be able to refer to data stored in the memory 160 and to rewrite the data in the memory 160. The communication I/F 170 is an interface circuit that communicates with the microcomputer 1 and the other monitoring ICs 22 to 2n.

The detection control unit 141 outputs instructions to the cell equalization circuit 110 and the AD converter 120 in response to commands sent from the microcontroller 1. For example, the detection control unit 141 outputs instructions to detect cell voltages and instructions to equalize voltages to the cell equalization circuit 110. In addition, the detection control unit 141 outputs, as instructions for voltage equalization, an instruction to turn on the even switch 11E and an instruction to turn on the odd switch 11O at different times.

The communication control unit 142 receives commands via the communication I/F 170 and transmits data indicating the cell voltage value and the like via the communication I/F 170. The AD detection correction unit 143 acquires the cell voltage value that has been AD converted by the AD converter 120. The AD detection correction unit 143 corrects the acquired cell voltage value using a correction coefficient stored in the memory 160.

In particular, when an equalization command is issued from the microcomputer 1, the first monitoring IC 21 performs voltage equalization by switching the on/off control target between the even switch 11E and the odd switch 11O at predetermined time intervals based on the count value while the microcomputer 1 is not running. This is to prevent heat generation and malfunction of the first monitoring IC 21 from occurring when adjacent equalization switches are both turned on and the current for the two filters 4 is discharged simultaneously. The equalization switch of the control target that is turned on can also be called the on target switch.

The processing operation of the battery ECU 10 will now be described with reference to Figures 4, 5, and 6. Note that the battery ECU operation in Figure 6 mainly indicates the operation of the microcomputer 1. Also, vehicle IG in Figure 6 is an abbreviation for the vehicle's ignition switch.

First, the processing operation of the microcomputer 1 will be described with reference to FIG. 4. Here, as shown in FIG. 6, an example is used in which the battery ECU 10 is started (on) even when the vehicle IG is off, and then the battery ECU 10 is stopped (off). The state in which the battery ECU 10 is started is the same as the state in which the microcomputer 1 is started. The state in which the battery ECU 10 is stopped is the same as the state in which the microcomputer 1 is not started. The state in which the microcomputer 1 is not started indicates a state in which the microcomputer 1 periodically alternates between normal operation and standby operation. Note that in FIG. 4, the battery ECU 10 is abbreviated as ECU.

For example, the microcomputer 1 starts up when the vehicle IG is off and at a constant interval, and performs the processing operations shown in the flowchart of FIG. 4. The microcomputer 1 may also start up when a predetermined condition is satisfied while the vehicle IG is off, and perform the processing operations shown in the flowchart of FIG. 4.

In step S11, the ECU is started. The microcomputer 1 starts the battery ECU 10 by transitioning from standby operation to normal operation. The microcomputer 1 transitions from standby operation to normal operation, for example, by the CPU outputting a power supply hold signal that holds the power supply from the auxiliary battery 30.

In step S12, cell voltage measurement is performed (voltage acquisition section). The microcontroller 1 detects the cell voltage of each battery cell 201-20n by sending a detection command to each monitoring IC 21-2n. More specifically, the microcontroller 1 sends a detection command to each monitoring IC 21-2n. In response to the detection command, each monitoring IC 21-2n performs AD conversion on the cell voltage value of each battery cell 201-20n using the AD converter 120. Then, each monitoring IC 21-2n returns the AD converted cell voltage value to the microcontroller 1. Thus, the microcontroller 1 acquires the cell voltage value of each battery cell 201-20n detected by each monitoring IC 21-2n.

In step S13, the cell voltages are stored (storage unit). The microcontroller 1 stores the cell voltage values transmitted from each of the monitoring ICs 21 to 2n in the storage device.

In step S14, it is determined whether or not the circuit is faulty (diagnosis unit). The microcontroller 1 determines whether or not the circuit of each of the monitoring ICs 21 to 2n is faulty. If the microcontroller 1 does not determine that the circuit of each of the monitoring ICs 21 to 2n is faulty, it proceeds to step S15, and if it determines that the circuit of each of the monitoring ICs 21 to 2n is faulty, it ends the processing operation of FIG. 4.

For example, the microcontroller 1 compares the current value, which is the current cell voltage value, with the previous value, which is the cell voltage value stored during the previous startup. The current cell voltage value is the cell voltage value stored in step S13 this time. On the other hand, the cell voltage value stored during the previous startup is the cell voltage value stored in the storage device in step S13 the previous time. Note that the microcontroller 1 may delete the previous value when the processing of step S14 is completed.

Then, the microcontroller 1 can determine that each of the monitoring ICs 21 to 2n is faulty if the current value and the previous value do not satisfy a predetermined correspondence relationship. In other words, the microcontroller 1 determines that each of the monitoring ICs 21 to 2n is not faulty if the current value and the previous value satisfy a predetermined correspondence relationship.

In addition, if the microcomputer 1 can determine that voltage equalization has been performed based on the difference between the current value and the previous value, it considers that each of the monitoring ICs 21 to 2n is not malfunctioning and that the specified correspondence is satisfied. On the other hand, if the microcomputer 1 cannot determine that voltage equalization has been performed based on the difference between the current value and the previous value, it considers that each of the monitoring ICs 21 to 2n is malfunctioning and that the specified correspondence is not satisfied.

The microcontroller 1 transmits, for example, diagnostic commands to each of the monitoring ICs 21-2n. Each of the monitoring ICs 21-2n turns on and off each of the equalization switches 111-11n in response to the diagnostic command to diagnose whether or not there is a fault in the circuit. Each of the monitoring ICs 21-2n then sends a reply to the microcontroller 1.

In step S15, it is determined whether or not equalization is necessary. The microcontroller 1 refers to all the cell voltage values stored in the storage device in step S13. The microcontroller 1 then determines whether or not voltage equalization is necessary based on each cell voltage value. For example, the microcontroller 1 determines that voltage equalization is necessary when there is variation in the cell voltage values of the battery cells 201-205. The microcontroller 1 may also determine that voltage equalization is necessary when the cell voltage values of the battery cells 201-205 differ by more than a predetermined value.

In step S16, an equalization instruction is issued. The microcontroller 1 issues an equalization instruction by sending a start command to each of the monitoring ICs 21 to 2n. By sending the start command, the microcontroller 1 can also be said to turn on equalization.

The microcontroller 1 also transmits information indicating the switching time (xmin) to each of the monitoring ICs 21-2n together with the start command. The switching time is the time it takes for each of the monitoring ICs 21-2n to switch the control target to be turned on and off between the even switch 11E and the odd switch 11O. In other words, the switching time is the time it takes for the even switch 11E and the odd switch 11O to switch between the control target to be turned on and the control target to be turned off.

For example, we will explain the case where the even switch 11E is the control target to be turned on and the odd switch 11O is the control target to be turned off. In this case, when the switching time has elapsed, each monitoring IC 21 to 2n switches the even switch 11E to the control target to be turned off, and switches the odd switch 11O to the control target to be turned on.

In this way, the switching time can be thought of as a period during which one of the even switch 11E and the odd switch 11O is the control target to be turned on, and the other is the control target to be turned off. Then, when this period has elapsed, the battery ECU 10 switches the control target to be turned on to the control target to be turned off, and switches the control target to be turned off to the control target to be turned on.

In this embodiment, a time in minutes is used as the switching time. However, the present disclosure is not limited to this, and a time in seconds can also be used as the switching time. Furthermore, the switching time may be a predetermined static time, or a time that changes dynamically. When the microcontroller 1 dynamically determines the switching time, it may determine the switching time based on the variation in each cell voltage value stored in the storage device. For example, the microcontroller 1 sets the switching time to be longer when the variation is large than when the variation is small.

The microcomputer 1 may determine whether or not voltage equalization is necessary for each battery block, or may determine whether or not voltage equalization is necessary for the entire main battery 20. In the former case, the microcomputer 1 sends a start command to the monitoring IC connected to the battery block for which it has determined that voltage equalization is necessary. In the latter case, the microcomputer 1 sends a start command to all monitoring ICs 21 to 2n.

In this way, the microcontroller 1 determines whether or not voltage equalization is necessary, provided that the circuit is not faulty. Also, the microcontroller 1 performs voltage equalization, provided that the circuit is not faulty and the cell voltages are not uniform.

In step S17, the ECU is stopped. The microcomputer 1 stops the battery ECU 10 by transitioning from normal operation to standby operation. For example, the microcomputer 1 transitions from normal operation to standby operation by the CPU stopping output of the power supply maintenance signal.

As explained below, once the battery ECU 10 sends a start command, each monitoring IC 21-2n automatically starts up and performs voltage equalization. Therefore, even if the microcomputer 1 determines that voltage equalization is necessary, it transitions to standby operation when it sends a start command.

Next, the processing operation of each of the monitoring ICs 21 to 2n will be described with reference to FIG. 5. When each of the monitoring ICs 21 to 2n receives the start command, it performs the processing operation shown in the flowchart of FIG. 5. The microcontroller 1 also transmits the switching time together with the start command. Therefore, each of the monitoring ICs 21 to 2n receives the switching time in addition to the start command. For example, the communication control unit 142 of each of the monitoring ICs 21 to 2n receives the start command and the switching time via the communication I/F 170.

In addition, when the microcontroller 1 transmits the start command and the switching time as described above, it transitions to standby operation. Therefore, each monitoring IC 21 to 2n performs the following steps S21 to S26 when the microcontroller 1 is not started.

In step S21, the switching time is set. Each monitoring IC 21 to 2n sets the received switching time as the time to switch the on/off controlled object between the even switch 11E and the odd switch 11O. For example, the detection control unit 141 stores the switching time received by the communication control unit 142 in the memory 160 for reference when determining the timing to switch the on/off controlled object. For this reason, in this embodiment, the switching time becomes the set time. Also, as shown in FIG. 6, the switching set time becomes xmin.

In step S22, the odd-numbered equalization switch is turned on. As shown in FIG. 6, when each monitoring IC 21-2n sets the switching time, it turns on odd switch 11O, which is the odd-numbered equalization switch. In other words, each monitoring IC 21-2n controls odd switch 11O to be turned on and even switch 11E to be turned off. At this time, for example, the detection control unit 141 outputs an instruction to turn on odd switch 11O to the cell equalization circuit 110 as an instruction for voltage equalization.

The cell equalization circuit 110 turns on the odd switch 11O in response to an instruction to turn on the odd switch 11O. This allows each of the monitoring ICs 21 to 2n to discharge multiple odd cells 20O. At this time, the even switch 11E is in an off state.

Also, as shown in FIG. 6, each monitoring IC 21-2n starts measuring the elapsed time when odd-numbered switch 11O is turned on. Each monitoring IC 21-2n measures the elapsed time by counting edges of the clock signal from oscillator 150 in logic circuit 140. However, the present disclosure is not limited to this, and the elapsed time may be measured by another method.

In step S23, it is determined whether or not it is the set time. Each monitoring IC 21 to 2n determines whether or not it is the set time, i.e., whether or not it is the switching time. For example, if the elapsed time being measured reaches the switching time, the detection control unit 141 determines that it is the set time and proceeds to step S24, but if the elapsed time has not reached the switching time, it does not determine that it is the set time and repeats step S23. In other words, if the logic circuit 140 determines that the count value obtained by counting the edges of the clock signal from the oscillator 150 has reached the switching time, it proceeds to step S23, and if it does not determine that the count value has reached the switching time, it repeats step S22.

In step S24, the even-numbered equalization switch is turned on. As shown in FIG. 6, when each monitoring IC 21-2n sets the switching time, it turns on the even switch 11E, which is the even-numbered equalization switch. In other words, each monitoring IC 21-2n controls the even switch 11E to be turned on and the odd switch 11O to be turned off. It can also be said that each monitoring IC 21-2n switches the control target to be turned on from the odd switch 11O to the even switch 11E, and switches the control target to be turned off from the even switch 11E to the odd switch 11O. At this time, for example, the detection control unit 141 outputs an instruction to turn on the even switch 11E to the cell equalization circuit 110 as an instruction for voltage equalization.

The cell equalization circuit 110 turns on the even switch 11E in response to an instruction to turn on the even switch 11E. This allows each of the monitoring ICs 21 to 2n to discharge multiple even cells 20E. At this time, the odd switch 11O is in an off state. As shown in FIG. 6, each of the monitoring ICs 21 to 2n starts measuring the elapsed time when it turns on the even switch 11E.

In step S25, similarly to step S23, it is determined whether or not the set time has elapsed. Then, for example, if the measured elapsed time reaches the switching time, the detection control unit 141 determines that the set time has elapsed and proceeds to step S26, whereas if the elapsed time has not reached the switching time, it does not determine that the set time has elapsed and repeats step S25.

In step S26, it is determined whether or not a stop command has been issued. Each monitoring IC 21 to 2n determines whether or not a stop command has been issued based on the stop command from the microcontroller 1. For example, if the detection control unit 141 has not received a stop command, it determines that there is no stop command and returns to step S22, whereas if the detection control unit 141 has received a stop command, it determines that there is a stop command and ends the flowchart in FIG. 5.

In this way, when an equalization command is issued from the microcomputer 1, each monitoring IC 21-2n switches the on/off control target between the even switch 11E and the odd switch 11O at predetermined time intervals based on the count value to perform voltage equalization. Also, when the microcomputer 1 is not running, each monitoring IC 21-2n switches the on/off control target between the even switch 11E and the odd switch 11O to perform voltage equalization. In other words, each monitoring IC 21-2n can automatically switch the on/off control target to perform voltage equalization regardless of the running state of the microcomputer 1.

In this way, even when the microcomputer 1 is not activated, the battery ECU 10 can perform voltage equalization by switching the on/off control targets of each monitoring IC 21-2n between the even switch 11E and the odd switch 11O. Therefore, the battery ECU 10 can reduce the number of times the microcomputer 1 is activated for voltage equalization, and can reduce the current consumption of the auxiliary battery 30.

In addition, in this embodiment, the order in which voltage equalization starts is preset to start from the odd-numbered cells 20O. However, in the present disclosure, the order in which voltage equalization starts may be preset to start from the even-numbered cells 20E. In other words, it is preferable that the order in which each monitoring IC 21-2n starts voltage equalization is preset to either the even-numbered cells 20E or the odd-numbered cells 20O. This allows the battery ECU 10 to prevent only one of the even-numbered cells 20E and the odd-numbered cells 20O from being equalized. Therefore, the battery ECU 10 can further suppress the variation in cell voltages among the multiple battery cells 201-20n.

As described above, each of the monitoring ICs 21 to 2n uses the counted value of the clock signal generated by the oscillator 150 as the count value. Therefore, the interval (switching time) for switching the on/off control target between the even switch 11E and the odd switch 11O in each of the monitoring ICs 21 to 2n may be preset based on the accuracy of the oscillator 150. It is preferable to make the switching time shorter as the accuracy of the oscillator 150 becomes poorer.

The lower the accuracy of the oscillator 150, the less likely each monitoring IC 21-2n is to switch the on/off control target at the correct switching time. In other words, an error occurs between the instructed switching time and the time when each monitoring IC 21-2n actually switches the on/off control target.

In other words, each monitoring IC 21-2n may turn on the target switch for longer than the time required to equalize the cell voltages. Also, each monitoring IC 21-2n may turn off the target switch without turning it on for the time required to equalize the cell voltages. This causes the discharge times of the battery cells 201-20n to vary, so even if the battery ECU 10 performs voltage equalization, it may not be able to properly equalize the cell voltages.

However, the battery ECU 10 can reduce the error when switching the on/off control target once by shortening the switching time as the accuracy of the oscillator 150 decreases. Therefore, the battery ECU 10 can improve the accuracy of voltage equalization. In other words, the battery ECU 10 can further suppress the variation in cell voltages among the multiple battery cells 201 to 20n.

In this embodiment, an example is used in which the odd switch 11O is turned on first. However, in the present disclosure, the even switch 11E may be turned on first.

In the present disclosure, the microcontroller 1 may determine which of the odd switch 11O and the even switch 11E is to be turned on first, and instruct each of the monitoring ICs 21 to 2n. In this case, the microcontroller 1 makes the determination based on each cell voltage value acquired in step S12.

In the present disclosure, each monitoring IC 21-2n may determine which of the odd switch 11O and the even switch 11E to turn on first. Each monitoring IC 21-2n makes the determination based on the detected cell voltage value.

In the present disclosure, step S26 may be determined by each of the monitoring ICs 21 to 2n. Each of the monitoring ICs 21 to 2n makes the determination based on the detected cell voltage value.

However, the present disclosure is not limited thereto. The battery ECU 10 may include at least one arithmetic processing unit (CPU), at least one memory device (MMR) as a storage medium for storing programs and data, and a monitoring IC. The battery ECU 10 is provided by a microcomputer having a computer-readable storage medium. The storage medium non-temporarily stores a computer-readable program. The storage medium may be provided by a semiconductor memory or a magnetic disk, etc. The control device may be provided by one computer or a set of computer resources linked by a data communication device. The program is executed by the control device to cause the control device to function as the device described in this specification and to function to execute the method described in this specification. The control device provides various elements. At least some of the elements may be referred to as means for performing a function, and in another perspective, at least some of the elements may be referred to as structural blocks or modules.

The means and/or functions provided by the battery ECU 10 can be provided by software recorded in a physical memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the battery ECU 10 is provided by an electronic circuit, which is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit.

The above describes a preferred embodiment of the present disclosure. However, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present disclosure.

1...microcomputer, 21-2n...first to nth monitoring ICs, 10...battery ECU, 20...main battery, 201-20n...first to nth battery cells, 30...auxiliary battery

Claims (4)

An on-board battery control device that controls a battery pack (20) including a plurality of battery cells (201-20n) including a plurality of even-numbered cells and a plurality of odd-numbered cells,
a plurality of monitoring ICs (21 to 2n) connected to the assembled battery and powered by the same, including a plurality of equalization switches (111 to 113) connected in series, and performing voltage equalization of the plurality of battery cells;
A microcomputer (1) that is powered by an auxiliary battery (30) and issues control instructions to the plurality of monitoring ICs,
The monitoring IC includes:
the equalization switches include a plurality of even numbered switches provided corresponding to the even numbered cells and a plurality of odd numbered switches provided corresponding to the odd numbered cells;
When an equalization instruction is issued from the microcomputer, while the microcomputer is not started, the voltage equalization is performed by switching the on/off control object between the even switches and the odd switches at predetermined time intervals based on a count value, wherein the count value is a counted value of a clock signal generated by an oscillator, and the interval at which the on/off control object is switched between the even switches and the odd switches is set in advance based on the accuracy of the oscillator. An on-board battery control device that controls a battery pack (20) including a plurality of battery cells (201-20n) including a plurality of even-numbered cells and a plurality of odd-numbered cells,
a plurality of monitoring ICs (21 to 2n) connected to the assembled battery and powered by the same, including a plurality of equalization switches (111 to 113) connected in series, and performing voltage equalization of the plurality of battery cells;
The monitoring IC is provided with a microcomputer (1) that can be in a non-activated state in which a normal operation and a standby operation are periodically repeated, is powered by an auxiliary battery (30), and issues control instructions to the plurality of monitoring ICs during the normal operation,
The monitoring IC includes:
the equalization switches include a plurality of even numbered switches provided corresponding to the even numbered cells and a plurality of odd numbered switches provided corresponding to the odd numbered cells;
When an equalization instruction is issued from the microcomputer, in a state in which the microcomputer is not activated, the voltage equalization is performed by switching the on/off control targets between the even switches and the odd switches at predetermined time intervals based on a count value,
An in-vehicle battery control device that uses a counted value of a clock signal generated by an oscillator as the count value, and the interval at which the controlled object is switched on and off by the even switch and the odd switch is preset based on the accuracy of the oscillator . 3. The vehicle-mounted battery control device according to claim 1 , wherein the monitoring IC presets an order in which the voltage equalization is to be started for the even-numbered cells or the odd-numbered cells. The microcomputer is
A voltage acquisition unit (S12) that acquires a cell voltage value of each battery cell detected by the monitoring IC;
A storage unit (S13) that stores the acquired cell voltage value;
A diagnostic unit (S14) that performs a fault diagnosis on the monitoring IC,
4. The vehicle battery control device according to claim 1, wherein the diagnosis unit compares a present value, which is the current cell voltage value, with a previous value, which is the cell voltage value stored during a previous startup, and determines that the monitoring IC is faulty if the present value and the previous value do not satisfy a predetermined correspondence relationship.

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