JP2021072672A - Battery control device and battery control method - Google Patents

Abstract

To provide a battery control device and a battery control method capable of performing flexible battery control while ensuring high accuracy and high reliability.SOLUTION: A battery control device (100) has a first estimation unit (50), a second estimation unit (60), and a control unit (70). The first estimation unit (50) estimates a first voltage (VSPE1) of a particular battery based on a difference between a total voltage of a plurality of batteries and a total voltage of batteries other than a particular battery among the plurality of batteries. The second estimating unit (60) estimates a second voltage (VSPE2) of a particular battery based on a state of charging estimated by summing a current of each of the plurality of batteries. The control unit (70) determines the accuracy of the first voltage (VSPE1) and the second voltage (VSPE2) to control the plurality of batteries (B1 to Bn) using the more accurate one of the first voltage (VSPE1) and the second voltage (VSPE2).SELECTED DRAWING: Figure 3

Description

The present invention relates to a battery control device and a battery control method.

Patent Document 1 describes a cell voltage estimation device for estimating a cell voltage when the cell voltage sensor of a driving battery of an electric vehicle is abnormal so that running can be continued within a range in which the battery cell does not become overcharged. It is disclosed.

The cell voltage estimation device includes a plurality of battery cells constituting a drive battery, an electric load, a capacitor, a capacitor voltage detection unit, a voltage sensor abnormality detection unit, a correlation storage unit, and a first estimation unit. I have. The sum of the cell voltages of the plurality of battery cells is applied to the electric load. The sum of the cell voltages of a plurality of battery cells is applied to the capacitor. The capacitor voltage detector detects the capacitor voltage applied to the capacitor. The voltage sensor abnormality detection unit detects an abnormality of the voltage sensor provided in each battery cell. The correlation storage unit stores the correlation between the voltage generated by the capacitor voltage detection unit and the total cell voltage when the voltage sensor is normal and the vehicle is in a predetermined driving state. When an abnormality is detected by the voltage sensor abnormality detection unit, the first estimation unit is a voltage sensor based on the data of the correlation storage unit, the voltage detected by the capacitor voltage detection unit, and the total battery voltage of the cell voltage. Estimates the voltage of the abnormal battery cell.

Japanese Unexamined Patent Publication No. 2018-098143

In the cell voltage estimation device of Patent Document 1, the voltage sensor estimates the voltage of an abnormal battery cell based on the total value of the voltages of the voltage sensors provided in each battery cell. Therefore, if there is an error in the voltage of the voltage sensor, the error may be accumulated by the amount of each voltage sensor, and as a result, the estimation accuracy of the voltage of the battery cell in which the voltage sensor is abnormal may deteriorate.

Further, in an electric vehicle (EV) equipped with a lithium ion secondary battery (LIB: Lithium Ion Battery), the safety of the battery may be ensured by monitoring the voltage of all the battery cells. Therefore, if voltage detection becomes impossible even for one cell due to some kind of failure, fail-safe that prohibits the use of the battery is executed, and the vehicle becomes impossible to travel.

The present invention has been made based on the above awareness of the problems, and provides a battery control device and a battery control method capable of ensuring high accuracy and high reliability and performing flexible battery control. With the goal.

The battery control device of the present embodiment is a battery control device that controls a plurality of batteries connected in series, and has a voltage detection unit that detects the voltage of each of the plurality of batteries and a voltage detection unit that detects the total voltage of the plurality of batteries. A total voltage detection unit, a detection unit that detects that the voltage of a specific battery among a plurality of batteries cannot be detected by the voltage detection unit, a total voltage of a plurality of batteries, and a plurality of batteries other than the specific battery. A specific battery based on the first estimation unit that estimates the first voltage of a specific battery based on the difference from the total voltage of the batteries and the charging state estimated by integrating the currents of each of the plurality of batteries. A second estimation unit that estimates the second voltage of the above, determines the accuracy of the first voltage and the second voltage, and controls a plurality of batteries by using the higher accuracy of the first voltage and the second voltage. It is characterized by having a control unit.

The battery control method of the present embodiment is a battery control method for controlling a plurality of batteries connected in series, and is a step of detecting the voltage of each of the plurality of batteries and a step of detecting the total voltage of the plurality of batteries. And the step of detecting that the voltage of a specific battery among a plurality of batteries cannot be detected by the voltage detector, the total voltage of the plurality of batteries, and the total voltage of the batteries other than the specific battery among the multiple batteries. A step of estimating the first voltage of a specific battery based on the difference between the above, and a step of estimating the second voltage of a specific battery based on the charging state estimated by integrating the currents of each of the plurality of batteries. It is characterized by having a step of determining the accuracy of the first voltage and the second voltage, and controlling a plurality of batteries by using whichever of the first voltage and the second voltage has the higher accuracy.

As a result, as the voltage of the specific battery for which the voltage detection unit cannot detect the voltage, the one with the higher accuracy, the first voltage according to the first estimation or the second voltage according to the second estimation, is used. It is possible to ensure high accuracy and high reliability and to execute flexible control of the battery.

When the current integration time of the plurality of batteries is shorter than the predetermined time threshold, the control unit determines that the second voltage is more accurate than the first voltage, and controls the plurality of batteries using the second voltage. When the current integration time of a plurality of batteries is equal to or longer than a predetermined time threshold, it is possible to determine that the first voltage has higher accuracy than the second voltage and control the plurality of batteries using the first voltage. it can.

As a result, the higher accuracy of the first voltage based on the first estimation and the second voltage based on the second estimation is used with the current integration time of the plurality of batteries as a reference (index). , It is possible to ensure high accuracy and high reliability and to execute flexible control.

When the current average value of the plurality of batteries is lower than the predetermined current threshold value, the control unit determines that the second voltage is more accurate than the first voltage, and controls the plurality of batteries using the second voltage. When the current average value of a plurality of batteries is equal to or higher than a predetermined current threshold value, it is possible to determine that the first voltage has higher accuracy than the second voltage and control the plurality of batteries using the first voltage. it can.

As a result, the higher accuracy of the first voltage based on the first estimation and the second voltage based on the second estimation is used with the current average value of the plurality of batteries as a reference (index). , It is possible to ensure high accuracy and high reliability and to execute flexible control.

When the temperature of the plurality of batteries is higher than a predetermined temperature threshold, the control unit determines that the second voltage has higher accuracy than the first voltage, controls the plurality of batteries using the second voltage, and controls the plurality of batteries. When the temperature of the battery is equal to or lower than a predetermined temperature threshold, it can be determined that the first voltage has higher accuracy than the second voltage, and a plurality of batteries can be controlled using the first voltage.

As a result, the higher accuracy of the first voltage based on the first estimation and the second voltage based on the second estimation is used with the temperature of the plurality of batteries as a reference (index). Further, it is possible to ensure high accuracy and high reliability and execute flexible control.

The first estimation unit sets the sum of the total voltage measurement tolerances of the plurality of batteries by the voltage detection unit as the maximum first voltage, and sets the total voltage measurement tolerances of the plurality of batteries by the voltage detection unit. The subtracted voltage can be used as the minimum first voltage, the maximum first voltage can be used as the first voltage when charging the plurality of batteries, and the minimum first voltage can be used as the first voltage when the plurality of batteries are discharged.

As a result, the preferred one of the maximum first voltage and the minimum first voltage is used as the first voltage according to the charging / discharging of the plurality of batteries, so that the estimation accuracy of the first voltage can be improved. As a result, it is possible to further ensure high accuracy and high reliability and perform flexible control for a specific battery and thus a plurality of batteries.

The second estimation unit obtains the maximum second voltage and the minimum second voltage based on the measurement tolerance of the current meter that detects the current of each of the plurality of batteries and the measurement tolerance of the internal resistance of the plurality of batteries, and obtains the maximum second voltage and the minimum second voltage of the plurality of batteries. When charging, the maximum second voltage can be used as the second voltage, and when discharging the plurality of batteries, the minimum second voltage can be used as the second voltage.

As a result, the preferred one of the maximum second voltage and the minimum second voltage is used as the second voltage according to the charging / discharging of the plurality of batteries, so that the estimation accuracy of the second voltage can be improved. As a result, it is possible to further ensure high accuracy and high reliability and perform flexible control for a specific battery and thus a plurality of batteries.

According to the present invention, it is possible to provide a battery control device and a battery control method capable of ensuring high accuracy and high reliability and performing flexible battery control.

It is a figure which shows the use example of the battery control device by this embodiment. It is a figure which shows an example of the internal structure of the battery control device by this embodiment. It is a block diagram which shows an example of the internal structure of a processor.

FIG. 1 is a diagram showing a usage example of the battery control device 100 according to the present embodiment. In this embodiment, the battery control device 100 is used in an electric vehicle 1 such as an electric vehicle or a plug-in hybrid vehicle, and measures the voltage of the secondary battery 102 for supplying a current to the traveling motor 111. The battery control device 100 corresponds to a monitoring ECU (Electronic Control Unit). The battery control device 100 is included in the battery pack 10.

The battery pack 10 includes a battery control device 100, a battery ECU 101, a secondary battery 102, a current sensor 103, a thermistor 104, and relays 105 and 106. The battery pack 10 may have other circuit configurations not shown in FIG.

As the battery control device 100, for example, a circuit using a CPU (Central Processing Unit), a multi-core CPU, a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device)), or the like can be considered. Further, the battery control device 100 includes a memory provided inside or outside, and reads and executes a program for controlling each part of the secondary battery 102 stored in the memory. Although the battery control device 100 will be used in the present embodiment, the control executed by the battery control device 100 may be performed by, for example, one or more ECUs mounted on the electric vehicle 1. ..

The secondary battery 102 is realized by an assembled battery including a plurality of battery modules connected in series. Then, the battery control device 100 measures the voltage of the secondary battery 102 and also measures the voltage of each battery module constituting the secondary battery 102. Further, each battery module is composed of, for example, a plurality of battery cells connected in series. In this case, the battery control device 100 may measure the voltage of each battery cell. In the following description, each battery module or each battery cell may be simply referred to as a "battery".

The current sensor 103 is composed of, for example, a Hall element or a shunt resistor, and detects the current flowing through the secondary battery 102, the relays 105, and 106. The thermistor 104 detects the temperature of the secondary battery 102 or the ambient temperature of the secondary battery 102. The battery control device 100 sends the battery state information indicating the voltage of the secondary battery 102, the current detected by the current sensor 103, and the temperature detected by the thermistor 104 to the battery ECU 101.

The charger 21 charges the secondary battery 102. At this time, the charger 21 may charge the secondary battery 102 based on the voltage monitored by the battery control device 100 and the current monitored by the current sensor 103. When the electric vehicle 1 is traveling, a current is supplied from the secondary battery 102 to the traveling motor 111. At this time, the inverter circuit 112 converts the DC power of the secondary battery 102 into AC power and outputs it to the traveling motor 111. Further, at the time of regeneration, the inverter circuit 112 converts the AC power of the traveling motor 111 into DC power and outputs it to the secondary battery 102.

A relay 105 is provided between the secondary battery 102 and the charger 21. Further, on the negative electrode side of the secondary battery 102, a relay 106 is provided between the secondary battery 102 and the traveling motor 111. Then, the battery ECU 101 controls the relays 105 and 106. For example, when the charger 21 charges the secondary battery 102, the battery ECU 101 controls the relays 105 and 106 to be in the ON state. When the secondary battery 102 is in the overcharged state, the battery ECU 101 may control the relays 105 and 106 to be in the off state. When the electric vehicle 1 is traveling, the battery ECU 101 controls the relay 106 in the on state and the relay 105 in the off state. When the secondary voltage 101 is in the over-discharged state, the battery ECU 101 may control the relays 105 and 106 to be in the off state.

As the battery ECU 101, for example, a circuit using a CPU, a multi-core CPU, a programmable device, a PLD, or the like can be considered. Further, the battery ECU 101 includes a memory provided inside or outside, and reads and executes a program for controlling each part of the battery pack 10 stored in the memory.

The battery ECU 101 determines the limited output power (Wout) information and regenerative power (Win) information based on the upper and lower thresholds of the SOC (State Of Charge) of the secondary battery 102. When the SOC of the secondary battery 102 is equal to or lower than the lower limit threshold value, the limited output power (Wout) information is transmitted to the vehicle ECU 113, and when the SOC of the secondary battery 102 is equal to or higher than the upper limit threshold value, the limited regenerative power (Wout) ( Win) Information is transmitted to the vehicle ECU 113.

The vehicle ECU 113 limits the output from the secondary battery 102 to the traveling motor 111 according to the output power (Wout) information from the battery ECU 101. Further, the vehicle ECU 113 limits the regeneration from the traveling motor 111 to the secondary battery 102 according to the regenerative power (Win) information from the battery ECU 101. Specifically, the vehicle ECU 113 limits the output power of the inverter circuit 112 based on the output power (Wout) information based on the SOC of the secondary battery 102, and limits the output of the traveling motor 111. Further, the vehicle ECU 113 limits the input power of the inverter circuit 112 based on the regenerative power (Win) information based on the SOC of the secondary battery 102, and limits the regeneration from the traveling motor 111.

The method for limiting the output power of the inverter circuit 112 is not particularly limited because a known method can be adopted. For example, as an example of the method of limiting the output power, the vehicle ECU 113 can adopt a method of lowering the duty ratio by changing the switching frequency of the switches constituting the inverter circuit 112.

The battery ECU 101 determines the output power (Wout) information and the regenerative power (Win) information based on the SOC of the secondary battery 102, but this is not the case. For example, the battery ECU 101 may determine the limited output power (Wout) information and the regenerative power (Win) information based on the upper limit threshold value and the lower limit threshold value of the voltage of the secondary battery 102. When the voltage of the secondary battery 102 is below the lower limit threshold, the limited output power (Wout) information is transmitted to the vehicle ECU 113, and when the voltage of the secondary battery 102 is above the upper limit threshold, the limited regenerative power (Wout) ( Win) Information is transmitted to the vehicle ECU 113.

In this case, the vehicle ECU 113 limits the output from the secondary battery 102 to the traveling motor 111 according to the output power (Wout) information based on the voltage of the secondary battery 102. Further, the vehicle ECU 113 limits the regeneration from the traveling motor 111 to the secondary battery 102 according to the regenerative power (Win) information based on the voltage of the secondary battery 102.

The vehicle ECU 113 may give a current command value to the charger 21 based on the output power (Wout) information and the regenerative power (Win) information of the secondary battery 102 received from the battery ECU 101. Further, the vehicle ECU 113 can give a control signal to the battery ECU 101 as needed. The battery ECU 101 and the vehicle ECU 113 may be connected to each other so as to be able to communicate with each other by CAN (Controller Area Network) communication.

FIG. 2 is a diagram showing an example of the internal configuration of the battery control device 100 according to the present embodiment. In this embodiment, the battery control device 100 measures the voltage of the secondary battery 102. As shown in FIG. 2, the secondary battery 102 includes n batteries B1 to Bn connected in series. Then, the battery control device 100 measures the voltage of the secondary battery 102 and also measures the potentials of the positive electrode terminals of the batteries B1 to Bn. As a result, the battery control device 100 can measure the voltage of each battery B1 to Bn. Each of the batteries B1 to Bn may be composed of a plurality of batteries connected in parallel.

The battery control device 100 includes a resistance circuit 11, a resistance circuit 12, a plurality of relay elements S1 to Sn, and a control unit 13. The battery control device 100 may include other circuit elements not shown in FIG.

The resistance circuit 11 is composed of a reference resistor R0 and resistors R1 to Rn. The reference resistors R0 and resistors R1 to Rn are connected in series in order. Further, the reference resistors R0 and the resistors R1 to Rn are used as voltage dividing resistors. That is, the resistance circuit 11 is an example of a resistance voltage dividing circuit. The resistance values of the resistors R1 to Rn may or may not be the same as each other. The resistance circuit 12 includes a reference resistor r0 and an auxiliary resistor r1. The reference resistor r0 and the auxiliary resistor r1 are connected in series. Further, the reference resistor r0 and the auxiliary resistor r1 are used as voltage dividing resistors. That is, the resistance circuit 12 is also an example of the resistance voltage dividing circuit.

One terminal (battery side terminal) of each relay element S1 to Sn is electrically connected to a positive electrode terminal of the corresponding batteries B1 to Bn. For example, the battery-side terminal of the relay element S1 is connected to the positive electrode terminal of the battery B1, and the battery-side terminal of the relay element Sn is connected to the positive electrode terminal of the battery Bn. Further, the other terminal (control unit side terminal) of each relay element S1 to Sn is electrically connected to one terminal (positive side terminal) of the corresponding resistors R1 to Rn. For example, the control unit side terminal of the relay element S1 is connected to the positive terminal of the resistor R1, and the control unit side terminal of the relay element Sn is connected to the positive terminal of the resistor Rn. That is, the corresponding relay elements S1 to Sn are provided between the positive electrode terminals of the batteries B1 to Bn and the positive terminal of the corresponding resistors R1 to Rn. The state of each relay element S1 to Sn is controlled by the control unit 13.

The other terminal (negative terminal) of the resistor R1 is connected to one terminal (positive terminal) of the reference resistor R0. The other terminal (negative terminal) of the reference resistor R0 is electrically connected to the negative terminal of the secondary battery 102 (that is, the negative terminal of the battery B1). Then, the voltage Va at the connection point between the reference resistor R0 and the resistor R1 is given to the control unit 13.

The resistance circuit 12 is electrically connected to the resistance circuit 11 in parallel. That is, one terminal (positive terminal) of the auxiliary resistor r1 is connected to the positive terminal of the resistor Rn and the control unit side terminal of the relay element Sn. The other terminal (negative terminal) of the auxiliary resistor r1 is connected to one terminal (positive terminal) of the reference resistor r0. The other terminal (negative terminal) of the reference resistor r0 is connected to the negative terminal of the reference resistor R0 and the negative terminal of the secondary battery 102. Then, the voltage Vb at the connection point between the reference resistor r0 and the auxiliary resistor r1 is given to the control unit 13.

The control unit 13 measures the voltage of the secondary battery 102 and the potential of the positive electrode terminals of the batteries B1 to Bn by detecting the voltage Va and the voltage Vb while controlling the relay elements S1 to Sn. Further, the control unit 13 can detect the failure of the resistance circuits 11 and 12 by monitoring the voltage Va and the voltage Vb while controlling the relay elements S1 to Sn.

The control unit 13 is realized by, for example, a microcomputer. In this case, the control unit 13 includes a processor 13A and a memory 13B. The processor 13A can measure the voltage of the battery by executing the program stored in the memory 13B. This program includes, for example, a description for controlling the relay elements S1 to Sn, a description for calculating the voltage of the battery based on the voltage Va and the voltage Vb, and a description for determining the failure of the resistance circuits 11 and 12. The memory 13B may store resistance information representing the resistance value of each resistor (R0 to Rn, r0 to r1).

The control unit 13 can measure the potential of the positive electrode terminals of the batteries B1 to Bn by using the output voltage Va of the resistance circuit 11 or the output voltage Vb of the resistance circuit 12.

The potential of the positive electrode terminal of the battery Bi (i = 1 to n) corresponds to the voltage between the potential of the negative electrode of the secondary battery 102 and the potential of the positive electrode terminal of the battery Bi. In the following description, the potentials of the positive terminals of the resistors R1 to Rn are represented by V1 to Vn, respectively. The potential of the positive terminal of the resistor Ri (i = 1 to n) corresponds to the voltage between the potential of the negative electrode of the secondary battery 102 and the potential of the positive terminal of the resistor Ri.

The control unit 13 selects one relay element from the relay elements S1 to Sn. Then, the control unit 13 acquires the voltage Va while controlling only the selected relay element in the ON state. Here, the control unit 13 controls the selected relay element Sk in the on state and controls the other relay elements in the off state. The relay element Sk represents a relay element connected to the battery Bk (that is, the kth battery module counting from the negative electrode of the secondary battery 102). When the relay element Sk is controlled to the on state and the other relay elements are controlled to the off state, the voltage Va is represented by the equation (1).

The control unit 13 calculates the voltage Vk by giving the measured value of the voltage Va to the equation (1). The voltage Vk represents the potential of the positive terminal of the resistor Rk (that is, the kth resistor counting from the reference resistor R0). Here, since the relay element Sk is controlled to be in the ON state, the voltage Vk is substantially the same as the potential of the positive electrode terminal of the battery Bk. Therefore, the control unit 13 can calculate the potential of the positive electrode terminal of the battery Bk corresponding to the selected relay element Sk based on the voltage Va.

Further, the control unit 13 acquires the voltage Vb while controlling only the selected relay element in the ON state. When the relay element Sk is controlled to the on state and the other relay elements are controlled to the off state, the voltage Vb is represented by the equation (2).

The control unit 13 calculates the voltage Vk by giving the measured value of the voltage Vb to the equation (2). The voltage Vk represents the potential of the positive terminal of the resistor Rk (that is, the kth resistor counting from the reference resistor R0). Here, since the relay element Sk is controlled to be in the ON state, the voltage Vk is substantially the same as the potential of the positive electrode terminal of the battery Bk. Therefore, the control unit 13 can calculate the potential of the positive electrode terminal of the battery Bk corresponding to the selected relay element Sk based on the voltage Vb. Then, the control unit 13 measures the potential of the positive electrode terminal of the secondary battery 102 corresponding to the selected relay element based on at least one of the voltage Va and the voltage Vb.

In this way, the control unit 13 controls the relay element selected from the relay elements S1 to Sn in the ON state, so that the selected relay element is selected based on at least one of the voltage Va and the voltage Vb. The potential of the positive electrode terminal of the corresponding secondary battery 102 can be measured. Specifically, when the relay element Sk is controlled to be in the ON state, the control unit 13 measures the potential of the positive electrode terminal of the battery Bk based on the output voltage Va of the resistance circuit 11, and the output voltage Vb of the resistance circuit 12 The potential of the positive electrode terminal of the battery Bk is measured based on.

Here, when measuring the potentials of the positive electrode terminals of all the batteries B1 to Bn, the control unit 13 detects the voltage Va and the voltage Vb while sequentially selecting the relay elements one by one. For example, the control unit 13 selects one relay element at a time in order from the relay elements connected to the battery having the lowest potential from the batteries B1 to Bn and controls the on state. In this case, at the time of the first measurement, the control unit 13 calculates the potential on the positive electrode terminal side of the battery B1 corresponding to the relay element S1 by detecting the voltages Va and Vb while controlling the relay element S1 in the ON state. To do. Then, the control unit 13 obtains the voltage of the battery B1 by the difference between the potential of the positive electrode terminal of the battery B1 and the potential of the negative electrode terminal of the secondary battery 102.

Subsequently, the control unit 13 detects the voltages Va and Vb while controlling one relay element S2 adjacent to the positive side of the relay element S1 in the ON state, thereby detecting the relay element adjacent to the positive side of the battery B1. The potentials on the positive electrode terminal side of the battery B2 corresponding to S2 are calculated respectively. That is, the control unit 13 calculates the potential of the positive electrode terminal of the battery B2 by detecting the voltages Va and Vb while controlling the relay element S2 in the ON state. Then, the control unit 13 obtains the voltage of the battery B2 by the difference between the potential of the positive electrode terminal of the battery B2 and the potential of the positive electrode terminal of the battery B1. After that, the potentials of each battery in the secondary battery 102 are sequentially measured one by one up to the battery Bn. As a result, even if one resistance circuit fails in the battery control device for voltage division, the voltage of the secondary battery 102 is detected by detecting the voltage Va or the voltage Vb by the resistance circuit 11 or the resistance circuit 12. Can be measured.

The control unit 13 can detect a failure of the resistance circuits 11 and 12 by using the output voltage Va of the resistance circuit 11 and the output voltage Vb of the resistance circuit 12. Specifically, the control unit 13 detects an abnormality in the resistance value of the resistors constituting the resistance circuits 11 and 12.

The battery control device 100 of the present embodiment controls a plurality of batteries B1 to Bn connected in series with the secondary battery 102. This battery control relates to, for example, calculation of a power limit value, charge / discharge control for overcharge protection and overdischarge protection. Then, this battery control is executed by the processor 13A of the control unit 13.

FIG. 3 is a block diagram showing an example of the internal configuration of the processor 13A. As shown in FIG. 3, the processor 13A includes a voltage detection unit 20, a total voltage detection unit 30, a detection unit 40, a first estimation unit 50, a second estimation unit 60, and a battery control unit (control unit). Has 70 and.

The voltage detection unit 20 detects the respective voltages V1 to Vn of the plurality of batteries B1 to Bn. For example, the voltage detection unit 20 measures the voltage Va and the voltage Vb while controlling the relay elements S1 to Sn, and gives the measured value of the voltage Va to the equation (1), or gives the measured value of the voltage Vb to (2). ), The respective voltages V1 to Vn of the plurality of batteries B1 to Bn are detected.

The total voltage detection unit 30 detects the total voltage of the plurality of batteries B1 to Bn. In the present embodiment, the total voltage of the plurality of batteries B1 to Bn corresponds to the output voltage (voltage at the connection point between the reference resistor r0 and the auxiliary resistor r1) Vb of the resistor circuit 12.

The detection unit 40 detects whether or not the voltage of each of the plurality of batteries B1 to Bn can be detected by the voltage detection unit 20. When the voltage detection unit 20 cannot detect the voltage of each of the plurality of batteries B1 to Bn, the detection unit 40 further detects that the voltage detection unit 20 cannot detect the voltage of a specific battery among the plurality of batteries B1 to Bn. To do.

Here, the "specific battery" means one or more batteries in which the voltage detection unit 20 cannot detect the voltage among the plurality of batteries B1 to Bn. For example, the voltage detection of the battery B1 can be performed. When it becomes impossible, the battery B1 corresponds to a "specific battery", and when the voltage detection of the battery Bn becomes impossible, the battery Bn corresponds to a "specific battery". Further, the "specific battery" may be read as, for example, an "arbitrary battery", a "voltage undetectable battery", a "first battery", or the like.

Although failure of a specific battery is not necessarily excluded as a factor that makes it impossible for the voltage detection unit 20 to detect a voltage for a specific battery, what is assumed in this embodiment is a voltage detection sensor (voltage detection unit 20). It is a side failure. For example, as described above, it is conceivable that the voltage detection of the battery B1 becomes impossible due to the failure of the resistor R1 of the resistance circuit 11, or the voltage detection of the battery Bn becomes impossible due to the failure of the resistor Rn of the resistance circuit 11. Be done. Further, when the voltage detection of the battery B1 becomes impossible due to the disconnection of the circuit connecting the battery B1 and the control unit 13 (processor 13A) or the failure of the relay element S1, the circuit connecting the battery Bn and the control unit 13 (processor 13A). It is also conceivable that the voltage detection of the battery Bn becomes impossible due to the disconnection of the battery or the failure of the relay element Sn. Using such a situation as a judgment material, the detection unit 40 detects that the voltage of a specific battery among the plurality of batteries B1 to Bn cannot be detected by the voltage detection unit 20. The detection unit 40 may detect that the voltage of a specific battery cannot be detected, for example, based on the ratio or difference between the voltage Va and the voltage Vb, or the voltage range that the voltage Va or the voltage Vb can take during normal operation. It may be detected that the voltage of a specific battery cannot be detected based on the fact that the battery is out.

The first estimation unit 50 is the first of a specific battery based on the difference between the total voltage Vb of the plurality of batteries B1 to Bn and the total voltage of the batteries other than the specific battery among the plurality of batteries B1 to Bn. Estimate the voltage V _SPE1. For example, when the battery B1 is a specific battery, the first voltage V of the battery B1 is based on the difference between the total voltage Vb of the plurality of batteries B1 to Bn and the total voltage of the batteries B2 to Bn other than the battery B1. Estimate _SPE1. Alternatively, when the battery Bn is a specific battery, the first battery Bn is based on the difference between the total voltage Vb of the plurality of batteries B1 to Bn and the total voltage of the batteries B1 to Bn-1 other than the battery Bn. Estimate the voltage V _SPE1.

Specifically, the first estimation unit 50 is the sum of the total measurement tolerances of the respective voltages of the plurality of batteries B1 to Bn by the voltage detection unit 20 (maximum voltage value considering the measurement tolerance) as the maximum first voltage. V _{MAX-SPE1 is defined as the minimum first voltage V MIN-SPE1} obtained by subtracting the total measurement tolerances of the respective voltages of the plurality of batteries B1 to Bn by the voltage detection unit 20 (minimum voltage value considering the measurement tolerances). To do.

For example, the number of a plurality of batteries (cells) is 12, the reference voltage of each battery (cell) is 3.5V, the measurement tolerance of the voltage of each battery (cell) is ± 10 mV, and 12 cells are used. It is assumed that one of the batteries (cells) cannot detect the voltage. In this case, the maximum voltage including the measurement tolerance of 12 batteries (cells) is (3.5V + 10mV) × 12 = 42.12V, and the minimum voltage including the measurement tolerance of 12 batteries (cells) is (3). .5V-10mV) × 12 = 41.88V. The maximum voltage including the measurement tolerance of 11 batteries (cells) other than the specific battery is (3.5V + 10mV) × 11 = 38.61V, and the measurement of 11 batteries (cells) other than the specific battery is performed. The minimum voltage including the tolerance is (3.5V-10mV) x 11 = 38.39V. Therefore, the maximum first voltage _VMAX-SPE1 is 42.12V-38.39V = 3.73V, and the minimum first voltage V _MIN-SPE1 is 41.88V-38.61V = 3.27V.

Then, the first estimation unit 50 uses the maximum first voltage V _MAX-SPE1 as the first voltage V _SPE1 when charging the plurality of batteries B1 to Bn, and the minimum first voltage V when the plurality of batteries B1 to Bn are discharged. _MIN-SPE1 is used as the first voltage V _SPE1. In this way, the preferred one of the _{maximum first voltage VMAX-SPE1} and the minimum first voltage V _MIN-SPE1 is used as _{the first voltage V SPE1} according to the charging / discharging of the plurality of batteries B1 to Bn. The estimation accuracy of the first voltage V _SPE1 can be improved. As a result, it is possible to further ensure high accuracy and high reliability and execute flexible control for a specific battery and thus a plurality of batteries B1 to Bn.

_{The second estimation unit 60 estimates the second voltage V SPE2} of a specific battery based on the charging state estimated by integrating the currents of the plurality of batteries B1 to Bn. Here, the currents of the plurality of batteries B1 to Bn can be detected by the current sensor 103.

The second estimation unit 60 has a maximum based on the measurement tolerance of the current sensor 103 (ammeter) that detects the current of each of the plurality of batteries B1 to Bn and the measurement tolerance of the internal resistance of the plurality of batteries B1 to Bn. The second voltage V _MAX-SPE2 and the minimum second voltage V _MIN-SPE2 are obtained (calculated / acquired).

The second estimation unit 60 estimates the OCV (Open Circuit Voltage) based on the SOC (State Of Charge) of the battery (cell) whose voltage cannot be detected. The second estimation unit 60 continues the SOC estimation by current integration and the OCV estimation based on the SOC estimation. The second estimation unit 60 estimates CCV (Closed Circuit Voltage), which is the current voltage (closed circuit voltage), based on the current value obtained by the current sensor 103 and the estimated resistance value (for example, direct current, polarization). At that time, the second estimating unit 60, taking into account the measurement tolerance by the current sensor 103, the resistance by using the maximum value, continues up to the second voltage _{V MAX-SPE2} and the minimum second voltage _{V MIN-SPE2} Calculate.

The measurement tolerance of the current sensor 103 is set to a predetermined value with respect to the current detection range of the current sensor 103 (for example, ± α). The resistance to polarization varies depending on the magnitude of the current and the time it flows. The maximum value of resistance can be dynamically determined according to the characteristic curve of resistance and temperature. In general, the resistance value increases as the temperature decreases, and decreases as the temperature increases, drawing a gentle curve. Therefore, the maximum value of the resistance can be a resistance value corresponding to the minimum value of the measurement tolerance of the temperature sensor (for example, thermistor 104). Alternatively, in consideration of the deterioration of the battery (resistance), the resistance value with respect to the temperature in the characteristic curve may be corrected to be high. Furthermore, when the distance between the battery (cell) provided with the temperature sensor (for example, thermistor 104) and the battery (cell) whose voltage cannot be detected is long, the maximum value and the minimum temperature are determined according to the distance between these batteries (cell). The value may be estimated. In this case, the battery control device 100 may hold a map that defines the relationship between the position of the battery (cell) and the temperature so that the map can be referred to.

Based on the above, the maximum second voltage _VMAX-SPE2 and the minimum second voltage _VMIN-SPE2 are expressed by the following equations.
Maximum second voltage _VMAX-SPE2 (maximum CCV) = OCV ± I (maximum current tolerance) R (minimum temperature tolerance)
Minimum second voltage V _MIN-SPE2 (minimum CCV) = OCV ± I (minimum current tolerance) R (maximum temperature tolerance)

Then, the second estimation unit 60 uses the maximum second voltage V _MAX-SPE2 as the second voltage V _SPE2 when charging the plurality of batteries B1 to Bn, and the minimum second voltage V when the plurality of batteries B1 to Bn are discharged. _MIN-SPE2 is used as the second voltage V _SPE2. In this way, the preferred one of the _{maximum second voltage VMAX-SPE2} and the minimum second voltage V _MIN-SPE2 is used as _{the second voltage V SPE2} according to the charging / discharging of the plurality of batteries B1 to Bn. The estimation accuracy of the second voltage V _SPE2 can be improved. As a result, it is possible to further ensure high accuracy and high reliability and execute flexible control for a specific battery and thus a plurality of batteries B1 to Bn.

Battery control unit (control unit) 70 is configured to determine a first voltage _{V SPE1} the accuracy of the second voltage _{V SPE2,} with a first voltage _{V SPE1} towards higher accuracy of the second voltage _{V SPE2,} more B1 to Bn are controlled. This battery control relates to, for example, calculation of a power limit value, charge / discharge control for overcharge protection and overdischarge protection. As the voltage of the specific battery for which the voltage detection unit 20 cannot detect the voltage, the one _{with the higher accuracy of the first voltage V SPE1} by the first estimation and the second voltage V _SPE2 by the second estimation is used to be specific. With respect to the battery and thus the plurality of batteries B1 to Bn, it is possible to ensure high accuracy and high reliability and to execute flexible control.

There is a degree of freedom in the "accuracy" that is the standard for selecting either the first voltage V _SPE1 or the second voltage V _SPE2 , but here, the current integration time of the plurality of batteries B1 to Bn and the plurality of batteries B1 The current average value of ~ Bn and the temperature of the plurality of batteries B1 to Bn will be described as an example. _{That is, it suffices} that the first voltage V SPE1 and the second voltage V _SPE2 are compared according to some reference (parameter), and either _{the first voltage V SPE1} or the second voltage V _SPE2 can be selected based on the comparison result.

[When using the current integration time of multiple batteries B1 to Bn]
Battery control unit 70, when current integration time T a plurality of batteries B1~Bn is shorter than a predetermined time threshold _{T threshhold (T <T threshhold),} the second voltage _{V SPE2} is accurate than the first voltage _{V SPE1} It is determined that the voltage is high, and the plurality of batteries B1 to Bn are controlled by using _{the second voltage V SPE2.} On the other hand, battery control unit 70, than when the current integration time T a plurality of batteries B1~Bn is the predetermined time threshold _{T threshhold} or (T ≧ _{T threshhold),} the first voltage _{V SPE1} second voltage _{V SPE2} It is determined that the accuracy is high, and the plurality of batteries B1 to Bn are controlled by using _{the first voltage V SPE1.}

Here, the predetermined time threshold _{T threshhold,} for example, can be set based on the offset error of the current sensor. Specifically, it is the time until the offset error of the current sensor is integrated and an error of a predetermined value or more occurs in the integrated current value.

Thus, the current integration time T a plurality of batteries B1~Bn basis (index), so use a first voltage _{V SPE1} by the first estimating the higher accuracy of the second voltage _{V SPE2} by the second estimation With respect to a specific battery and thus a plurality of batteries B1 to Bn, it is possible to further ensure high accuracy and high reliability and execute flexible control.

[When using the current average values of multiple batteries B1 to Bn]
Battery control unit 70, when the current average value I of the plurality of batteries B1~Bn is lower than a predetermined current threshold _{I threshhold (I <I threshhold),} the second voltage _{V SPE2} is accurate than the first voltage _{V SPE1} It is determined that the voltage is high, and the plurality of batteries B1 to Bn are controlled by using _{the second voltage V SPE2.} On the other hand, battery control unit 70, than when the current average value I of the plurality of batteries B1~Bn is the predetermined current threshold _{I threshhold} or (I ≧ _{I threshhold),} the first voltage _{V SPE1} second voltage _{V SPE2} It is determined that the accuracy is high, and the plurality of batteries B1 to Bn are controlled by using _{the first voltage V SPE1.} The current average value I is the average of the squares of the currents flowing through the plurality of batteries B1 to Bn and the average of the absolute values of the currents flowing through the plurality of batteries B1 to Bn.

Here, a predetermined current threshold _{I threshhold,} for example, can be set based on the gain error of the current sensor. Specifically, the current is such that the gain error of the current sensor is equal to or greater than a predetermined error.

Thus, the current average value I of the plurality of batteries B1~Bn basis (index), so use a first voltage _{V SPE1} by the first estimating the higher accuracy of the second voltage _{V SPE2} by the second estimation With respect to a specific battery and thus a plurality of batteries B1 to Bn, it is possible to further ensure high accuracy and high reliability and execute flexible control.

[When using the temperatures of multiple batteries B1 to Bn]
The temperature of the plurality of batteries B1 to Bn may be any of the temperatures of the plurality of batteries B1 to Bn, or may be the average temperature of the plurality of batteries B1 to Bn. When the temperature T of the plurality of batteries B1 to _Bn is higher than the _{predetermined temperature threshold T threshold (T> T threshold} ), the battery control unit 70 determines that the second voltage V _SPE2 is more accurate than the first voltage V _SPE1. After determining, the second voltage V _SPE2 is used to control a plurality of batteries B1 to Bn. Precision Meanwhile, the battery control unit 70, when the temperature T of the plurality of batteries B1~Bn is below the predetermined temperature threshold value _{T threshhold} (T ≦ _{T threshhold),} the first voltage _{V SPE1} than the second voltage _{V SPE2} Is determined to be high, and a plurality of batteries B1 to Bn are controlled using _{the first voltage V SPE1.}

Here, the predetermined temperature threshold value _{T threshhold,} for example, can be set based on the internal resistance of the plurality of batteries Bl to Bn. Specifically, the temperature is set so that the internal resistances of the plurality of batteries B1 to Bn become internal resistance values that cause an error of a predetermined value or more in the calculation of CCV.

Thus, the temperature T of the plurality of batteries B1~Bn basis (index), so use a first voltage _{V SPE1} by the first estimating the higher accuracy of the second voltage _{V SPE2} by the second estimation, the specific With respect to the above batteries and thus a plurality of batteries B1 to Bn, it is possible to further ensure high accuracy and high reliability and execute flexible control.

In the battery control device 100 described above, the power limiting fail-safe is temporarily performed at the timing when the detection unit 40 detects that the voltage of a specific battery among the plurality of batteries B1 to Bn cannot be detected by the voltage detection unit 20. To do. After that, the power limit value is calculated based on _{the first voltage V SPE1} or the second voltage V _SPE2 estimated / selected by the first estimation unit 50, the second estimation unit 60, and the battery control unit 70. _{At that time, when charging the plurality of batteries B1 to Bn, the maximum first voltage V MAX-SPE1} or the maximum second voltage V _MAX-SPE2 is used as the overcharge protection control, and when the plurality of batteries B1 to Bn are discharged, the maximum first voltage V MAX-SPE1 or the maximum second voltage V MAX-SPE2 is used. As the over-discharge protection control, the minimum first voltage V _MIN-SPE1 or the minimum second voltage V _MIN-SPE2 is used. In this way, even when the voltage detection unit 20 cannot detect the voltage of a specific battery among the plurality of batteries B1 to Bn, it is possible to realize fail-safe running of the electric vehicle 1 while ensuring safety. be able to.

When the voltage detection unit 20 can detect the respective voltages of the plurality of batteries B1 to Bn, the battery control unit 70 controls the plurality of batteries B1 to Bn based on the detected voltage. _{In this case, the first voltage V SPE1} and the second voltage V _SPE2 are not estimated (unnecessary) by the first estimation unit 50 and the second estimation unit 60.

The present invention is not limited to the above embodiment, and can be modified in various ways. In the above embodiment, the size, shape, function, and the like of the components shown in the accompanying drawings are not limited to this, and can be appropriately changed within the range in which the effects of the present invention are exhibited. In addition, it can be appropriately modified and implemented as long as it does not deviate from the scope of the object of the present invention.

100 Battery control device (monitoring ECU (Electronic Control Unit))
102 Rechargeable battery 103 Current sensor (ammeter)
B1 to Bn Multiple batteries 20 Voltage detection unit 30 Total voltage detection unit 40 Detection unit 50 First estimation unit 60 Second estimation unit 70 Battery control unit (control unit)

Claims (7)

A battery control device that controls multiple batteries connected in series.
A voltage detection unit that detects the voltage of each of the plurality of batteries,
A total voltage detection unit that detects the total voltage of the plurality of batteries, and
A detection unit that detects that the voltage of a specific battery among the plurality of batteries cannot be detected by the voltage detection unit, and
A first estimation unit that estimates the first voltage of the specific battery based on the difference between the total voltage of the plurality of batteries and the total voltage of the batteries other than the specific battery among the plurality of batteries.
A second estimation unit that estimates the second voltage of the specific battery based on the charging state estimated by integrating the currents of each of the plurality of batteries.
A control unit that determines the accuracy of the first voltage and the second voltage, and controls the plurality of batteries by using the higher accuracy of the first voltage and the second voltage.
A battery control device characterized by having. When the current integration time of the plurality of batteries is shorter than a predetermined time threshold, the control unit determines that the second voltage is more accurate than the first voltage, and uses the second voltage to describe the second voltage. When a plurality of batteries are controlled and the current integration time of the plurality of batteries is equal to or longer than a predetermined time threshold, it is determined that the first voltage has higher accuracy than the second voltage, and the first voltage is used. Use to control the plurality of batteries,
The battery control device according to claim 1. When the current average value of the plurality of batteries is lower than a predetermined current threshold value, the control unit determines that the second voltage is more accurate than the first voltage, and uses the second voltage. When a plurality of batteries are controlled and the current average value of the plurality of batteries is equal to or higher than a predetermined current threshold value, it is determined that the first voltage has higher accuracy than the second voltage, and the first voltage is used. Use to control the plurality of batteries,
The battery control device according to claim 1. When the temperature of the plurality of batteries is higher than a predetermined temperature threshold, the control unit determines that the second voltage is more accurate than the first voltage, and uses the second voltage to generate the plurality of batteries. When the batteries are controlled and the temperatures of the plurality of batteries are equal to or lower than a predetermined temperature threshold, it is determined that the first voltage is higher in accuracy than the second voltage, and the plurality of batteries are used. Control the battery,
The battery control device according to claim 1. The first estimation unit has a maximum first voltage obtained by adding the sum of the measurement tolerances of the voltages of the plurality of batteries by the voltage detection unit, and the voltage of each of the plurality of batteries by the voltage detection unit. The minimum first voltage is obtained by subtracting the total measurement tolerances, the maximum first voltage is used as the first voltage when charging the plurality of batteries, and the minimum first voltage is used as the first voltage when the plurality of batteries are discharged. Used as the first voltage,
The battery control device according to any one of claims 1 to 4. The second estimation unit obtains the maximum second voltage and the minimum second voltage based on the measurement tolerance of the current meter that detects the current of each of the plurality of batteries and the measurement tolerance of the internal resistance of the plurality of batteries. When charging the plurality of batteries, the maximum second voltage is used as the second voltage, and when discharging the plurality of batteries, the minimum second voltage is used as the second voltage.
The battery control device according to any one of claims 1 to 5. A battery control method that controls multiple batteries connected in series.
The step of detecting the voltage of each of the plurality of batteries and
The step of detecting the total voltage of the plurality of batteries and
A step of detecting that the voltage of a specific battery among the plurality of batteries cannot be detected by the voltage detection unit, and
A step of estimating the first voltage of the specific battery based on the difference between the total voltage of the plurality of batteries and the total voltage of the batteries other than the specific battery among the plurality of batteries.
A step of estimating a second voltage of the specific battery based on a charging state estimated by integrating the currents of each of the plurality of batteries.
A step of determining the accuracy of the first voltage and the second voltage, and controlling the plurality of batteries by using the higher accuracy of the first voltage and the second voltage.
A battery control method characterized by having.

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