JP6667373B2 - Battery device and vehicle - Google Patents

Description

  The present invention relates to a battery device including a battery configured by a plurality of cells and a vehicle.

  2. Description of the Related Art Conventionally, an equalization circuit in a battery ECU equalizes voltages of a plurality of unit cells for a battery including a plurality of unit cells connected in series with each other (see Patent Document 1). . In the equalization device described in Patent Literature 1, when the power supply voltage of the battery ECU drops, an equalization stop circuit different from the equalization circuit stops equalization by the equalization circuit.

Japanese Patent No. 5489525

  On the other hand, if a failure occurs in the battery ECU that causes the error in the detected value of the cell voltage to worsen, the error between the actual value and the detected value of the cell voltage increases, and the charge / discharge control of the battery becomes difficult. It will be difficult.

  The present invention has been made in view of the above points, and provides a battery device and a vehicle that can suppress the influence of a deterioration in an error in a detected voltage value of a unit cell when a failure occurs in a battery control unit. The task is to

In order to solve the above-described problem, a battery device of the present invention is a battery device including: a battery having a plurality of unit cells connected to each other; and a battery control unit configured to control charging and discharging of the battery. The battery control unit includes a voltage detection unit that detects voltages of the plurality of unit cells, an equalization unit that equalizes the voltages of the plurality of unit cells or a charging rate based on the voltage, and a battery control unit. A failure diagnosis unit that detects a failure, wherein when the failure diagnosis unit detects a failure, the battery control unit detects the voltage detection unit during equalization based on the type of the detected failure. The method is characterized in that the resulting error deterioration amount is estimated, and when the estimated error deterioration amount is equal to or larger than a threshold, equalization by the equalization unit is stopped .

  ADVANTAGE OF THE INVENTION According to this invention, when a failure occurs in a battery control part, the influence by the error deterioration of the detection voltage value of a unit cell can be suppressed.

1 is a diagram schematically illustrating a vehicle including a battery device according to an embodiment of the present invention. FIG. 3 is a circuit diagram illustrating a unit cell, an equalizing circuit, and a voltage detection circuit. It is a figure showing an example of an error deterioration amount table. 5 is a flowchart illustrating an operation example of the battery device according to the embodiment of the present invention.

  An embodiment of the present invention will be described in detail with reference to the drawings, taking a case where a battery device of the present invention is applied to a vehicle as an example. In the following description, the same elements will be denoted by the same reference symbols, without redundant description.

  As shown in FIG. 1, a vehicle 1 according to an embodiment of the present invention includes a battery device 2 and a notification unit 3. The battery device 2 includes a battery 10, a contactor 20, and a battery control unit 30.

<Battery>
The battery 10 supplies electric power to each device of the vehicle (discharge) and stores electric power generated by regenerative control of the vehicle (charge). The battery 10 is configured by connecting a plurality of unit cells 11 in series with each other.

<Contactor>
The contactor 20 is connected to the battery 10 and is a switch that opens and closes an electric circuit of the battery 10 under the control of the battery control unit 30. When the contactor 20 is in the closed state, the battery 10 performs charging and discharging. When the contactor 20 is in the open state, the battery 10 stops charging and discharging.

<Battery control unit>
The battery control unit 30 is a so-called battery ECU (Electrical Control Unit) that controls charging and discharging of the battery 10. The battery control unit 30 includes a Lithium Ion Battery Integrated Circuit (LIBIC) 31 that is a high-voltage circuit and a Micro Processing Unit (MPU) 32 that is a low-voltage circuit.

<LIBIC>
The LIBIC 31 includes an equalization circuit 31a, a voltage detection circuit 31b, a communication circuit 31c, and a failure diagnosis circuit 31d.

≪Equalization circuit≫
The equalizing circuit (equalizing unit) 31a is a circuit that can switch between a state in which the voltage or the state of charge (SOC) of the plurality of unit cells 11 is equalized and a state in which equalization is stopped. . The equalization circuit 31a equalizes the voltages of the plurality of unit cells 11 based on the voltage detected by the voltage detection circuit 31b.

  The equalization circuit 31a calculates the charging rates of the plurality of unit cells 11 based on the voltage detected by the voltage detection circuit 31b and the current and temperature of the battery 10 detected by a not-shown current detection unit and temperature detection unit. A configuration for equalization may be used. Here, the charging rate is obtained by detecting the integrated value of the voltage detected by the voltage detection circuit 31b, the current detected by a current detection unit (not shown) that detects the current flowing through the battery 10, and the temperature of the battery 10. The value is a value that can be calculated based on the temperature detected by the temperature detecting unit.

  That is, equalization is performed by discharging the unit cell 11 having a higher voltage or charge rate when the voltage or charge rate of the plurality of unit cells 11 varies, thereby obtaining the voltage or charge of the plurality of unit cells 11. Refers to equalizing the quantity.

  As shown in FIG. 2, the equalizing circuit 31a includes a discharge resistor 31a1 and a discharge switch 31a2 connected in series with each other.

≪Voltage detection circuit≫
As shown in FIG. 1, the voltage detection circuit (voltage detection unit) 31b is a voltage sensor that detects the value of each voltage of the plurality of unit cells 11. As shown in FIG. 2, the voltage detection circuit 31b is connected in parallel with the discharge resistor 31a1 and the discharge switch 31a2. The voltage detection circuit 31b includes an operational amplifier 31b1 and an AD converter 31b2 connected in series.

  The voltage detection circuit 31b has a function of correcting an equalization error caused by the equalization and an ECU error caused by the battery control unit (ECU) 30 with respect to the detected voltage value.

  The equalization error is an error generated when the discharge switch of the unit cell 11 having a high voltage for equalization is turned on and a discharge current flows. The equalization error includes an error due to the harness resistance, an error due to the discharge resistance, and an error due to the ON resistance of the discharge switch. The error due to the harness resistance is an error generated by the resistance of the harness that connects the two poles of the unit cell 11, the discharge resistor 31a1 and the discharge switch 31a2 of the equalizing circuit 31a. The error due to the discharge resistor is an error generated by the discharge resistor 31a1 of the equalizing circuit 31a. The error due to the ON resistance of the discharge switch is an error generated by the resistance of the discharge switch 31a2 when the discharge switch 31a2 of the equalizing circuit 31a is in the ON state. The value of the voltage detected by the voltage detection circuit 31a is corrected based on an estimated or preset harness resistance, discharge resistance, on-resistance, and discharge current. However, since the estimated or preset harness resistance, discharge resistance, on-resistance, and discharge current include an error, the corrected voltage value also includes an error, that is, an equalization residual error.

  The ECU error is an error generated by the linearity of the operational amplifier 31b1 for detecting the voltage of the unit cell 11 and the reference voltage of the AD converter 31b2. The non-volatile memory in the battery control unit 30 stores a deviation between an input voltage and a detected voltage when an accurate voltage is read at a manufacturing factory, that is, an ECU error. The voltage value detected by the voltage detection circuit 31b is corrected based on the stored deviation value.

  Further, as shown in FIG. 1, the battery control unit 30 (more specifically, the MPU 32) controls the charging and discharging of the battery 10 based on the voltage value of the unit cell 11 detected by the voltage detection circuit 31b. . Further, the battery control unit 30 (more specifically, the MPU 32) determines, in addition to the voltage value of the battery 10, a state of charge (SOC) based on the voltage value, current value, and temperature of the battery 10, or the temperature of the battery 10. Based on this, charge / discharge control of the battery 10 can be performed. For example, when the voltage value or the charging rate of the unit cell 11 detected by the voltage detection circuit 31b is equal to or less than a predetermined value, the battery control unit 30 performs a regenerative control of a motor (not shown) to It can be charged. That is, the LIBIC 31 of the battery device 2 includes a current detector that detects the value of the current flowing through the battery 10 and a temperature detector that detects the temperature of the battery 10. Then, the battery control unit 30 (more specifically, the MPU 32) controls the charging and discharging of the battery 10 based on the detection results of the voltage detection circuit 31b, the current detection unit, and the temperature detection unit.

≪Communication circuit≫
The communication circuit 31c is a circuit that performs communication with the MPU 32. The communication circuit 31c acquires the determination result from the MPU 32 and outputs the result to the equalization circuit 31a. Further, the communication circuit 31c outputs detection results of the voltage detection circuit 31b and the current detection unit and the temperature detection unit (not shown) to the MPU 32.

≪Failure diagnosis circuit≫
The failure diagnosis circuit 31d is a circuit that performs a self-diagnosis of a failure in the battery control unit 30, more specifically, the LIBIC 31. The failure diagnosis circuit (failure diagnosis unit) 31d outputs a failure detection result to the MPU 32.

  For example, examples of a failure diagnosis result (failure mode) include (1) parameter reading failure in equalization error correction, (2) parameter reading failure in ECU error correction, and (3) AD reference failure in cell voltage detection. (See FIG. 3).

  In the present embodiment, when the parameter cannot be read in the equalization error correction, the voltage detection accuracy during the equalization deteriorates by 100 [mV], and the voltage detection accuracy during the equalization stop does not deteriorate (± 0). [MV]). Further, when the parameter reading in the ECU error correction becomes impossible, the voltage detection accuracy deteriorates by 50 mV during equalization and during equalization stop. When AD reference deterioration in cell voltage detection occurs, the voltage detection accuracy deteriorates by 100 [mV] during equalization and during equalization stop.

<MPU>
The MPU 32 includes a CPU (Central Processing Unit), a ROM (Read-Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like. The MPU 32 has an equalization stop determination function and a charge / discharge stop determination function in addition to the charge / discharge control function of the battery 10 described above. That is, the MPU 32 includes a storage unit 32a, an equalization stop determination unit 32b, and a charge / discharge stop determination unit 32c as functional units for the equalization stop determination function and the charge / discharge stop determination function.

  The storage 32a stores an error deterioration amount map 32a1. As shown in FIG. 3, the error deterioration amount table 32a1 includes the failure mode detected by the failure diagnosis circuit, the error deterioration amount of the detected voltage value during equalization, and the error deterioration amount of the detected voltage value during equalization stop. 6 is a table showing the relationship between.

判定 Equalization and charge / discharge stop judgment unit≫
As illustrated in FIG. 1, the equalization stop determination unit 32b determines whether to stop equalization and whether to stop charging and discharging based on the diagnosis result of the failure diagnosis circuit 31a. The equalization and charging / discharging stop determination unit 32b estimates an error deterioration amount of the detection result of the voltage detection circuit 31b during the equalization based on the detected failure type (failure mode), and estimates the estimated error deterioration amount. Is equal to or larger than the threshold, the equalization by the equalization circuit 31a is stopped. Further, the equalization and charge / discharge stop determination unit 32b estimates the error deterioration amount of the detection result of the voltage detection circuit 31a when the equalization is stopped based on the type of the detected failure (failure mode), and estimates When the obtained error deterioration amount is equal to or more than the threshold value, charging / discharging of the battery 10 is stopped.

  The equalization and charge / discharge stop determination unit 32b outputs to the notification unit 3 a signal indicating the diagnosis result of the failure diagnosis circuit 31d, the equalization stop, and the charge / discharge stop.

<Notification section>
The notification unit 3 is a lamp, a display, a speaker, and the like provided on an instrument panel and the like in the cabin of the vehicle 1. The notification unit 3 obtains the signal output from the equalization and charge / discharge stop determination unit 32b, and performs a diagnosis result according to the obtained signal, and determines whether the equalization stop and the charge / discharge stop are performed by the occupant of the vehicle 1, specifically, driving. Notify others.

<Operation example>
Subsequently, an operation example of the battery control device 10 according to the embodiment of the present invention will be described with reference to FIG. As illustrated in FIG. 4, in a state where the battery control unit 30 is performing charge / discharge control of the battery 10 and the equalization circuit 31b is performing equalization of the voltage or the charging rate of the plurality of cells 11, The failure diagnosis circuit 31d detects a failure (step S1). When the failure diagnosis circuit 31d detects a failure (Yes in step S1), the failure diagnosis circuit 31d outputs a diagnosis result to the equalization and charge / discharge stop determination unit 32b. The equalization and charge / discharge stop determination unit 32b acquires a diagnosis result, and based on the acquired diagnosis result, worsens the respective errors during equalization of the detection result of the voltage detection circuit 31a and when the equalization is stopped. The amount is estimated (step S2). Here, when a plurality of failures have occurred, the equalization and charge / discharge stop determination unit 32b adds the error deterioration amounts of the plurality of failure modes.

  If the deterioration amount of the error during the equalization is smaller than a predetermined threshold (for example, 75 [mV]) (Yes in step S3), the flow ends, and the equalization is continued. The threshold value for the error deterioration amount is set by a preliminary test, simulation, or the like, and the same value is used for both the equalization stop determination and the charge / discharge stop determination.

  For example, in the failure mode (2), the equalization and the charge / discharge are continued because the amount of deterioration of the error during the equalization is 50 [mV], which is less than the threshold.

  If the deterioration amount of the error during equalization is equal to or larger than the threshold value (No in step S3) and the deterioration amount of the error when the equalization is stopped is smaller than the threshold value (Yes in step S4), The equalization and charge / discharge stop determination unit 32b outputs an equalization stop signal to the LIDIC 31 (step S5). The equalization circuit 31a acquires an equalization stop signal via the communication circuit 31c, and stops equalization based on the acquired equalization stop signal. That is, all the discharge switches of the equalizing circuit 31a are turned off.

  For example, in the failure mode (1), the deterioration amount of the error during equalization is 100 [mV] which is equal to or larger than the threshold, and the error deterioration amount when the equalization is stopped is 0 [mV] which is smaller than the threshold value. Therefore, equalization is stopped, and charging and discharging are continued.

  If the amount of error deterioration during equalization is equal to or greater than the threshold (No in step S3), and if the amount of error deterioration when equalization is stopped is equal to or greater than the threshold (No in step S4), The equalization and charge / discharge stop determination unit 32b outputs a charge / discharge stop signal to the contactor 20 (step S6). Contactor 20 acquires a charge / discharge stop signal, and stops charging / discharging of battery 10 based on the acquired charge / discharge stop signal. That is, the contactor 20 is in an open state.

  For example, in the failure mode (3), charging and discharging are stopped because the amount of error deterioration during equalization and when the equalization is stopped is both equal to or greater than the threshold. In this case, the configuration may be such that equalization is stopped together with the stop of charging and discharging.

  In the battery device 2 according to the embodiment of the present invention, when the failure diagnosis unit detects a failure, the equalization by the equalization unit is stopped, so that the equalization error based on the equalization is reduced, and the charge / discharge control of the battery 10 is performed. Can be continued. In this case, the driver of the vehicle 1 recognizes the occurrence of the failure and the stop of the equalization based on the notification result of the notification unit 3, and drives the vehicle 1 whose equalization has been stopped to an inspection place, a repair shop, or the like. be able to.

  Further, the battery device 2 stops the equalization when the error deterioration amount during the equalization is equal to or more than the threshold value. Therefore, it is preferable to determine the necessity of the stop of the equalization. The equalization error based on the equalization can be reduced, and the charge / discharge control of the battery 10 can be continued.

  In addition, the battery device 2 stops charging and discharging when the error deterioration amount when the equalization is stopped is equal to or larger than the threshold, so that the battery 10 can be suitably protected. In this case, the driver of the vehicle 1 recognizes the occurrence of the failure and the stop of the charge / discharge based on the notification result of the notification unit 3, and can stop the vehicle 1 in a safe place.

  As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and can be appropriately changed without departing from the gist of the present invention. For example, when the error deterioration amount when the equalization is stopped is equal to or larger than the threshold, the equalization and charge / discharge stop determination unit 32b outputs an equalization stop signal to stop the equalization by the equalization circuit 31a. In addition, a configuration may be adopted in which a signal indicating a failure occurrence, a stop of equalization, and a stop notice of charging / discharging is output to the notification unit 3. In this case, the equalization and charging / discharging stop determination unit 32b outputs a charging / discharging stop signal to perform charging / discharging when the driver that has recognized the notification of charging / discharging stop by the notification unit 3 stops the vehicle 1. It may be configured to stop.

  Further, the LIBIC 31 may include a current detection circuit (current detection unit) for detecting a current flowing through the battery 10 and a temperature detection circuit (temperature detection unit) for detecting the temperature of the battery 10. In this case, based on the voltage, current and temperature detected by each circuit, the equalization and charge / discharge stop determination unit 32b determines the ECU error during the equalization and during the equalization stop with respect to the detection value of the voltage detection circuit 31b. The residual correction error, the hard filter error, and the LIBIC error are estimated. Then, the equalization and charge / discharge stop determination unit 32b performs the equalization when the total of the ECU error correction residual error, the equalization error, the hard filter error, and the LIBIC error during the equalization is equal to or larger than a threshold (control allowable error). To stop. The equalization and charge / discharge stop determination unit 32b determines whether the total error of the ECU error correction error, the equalization error, the hard filter error, and the LIBIC error when the equalization is stopped is equal to or larger than a threshold (control allowable error). Stop charging and discharging. Here, the ECU error correction residual error is the maximum value of the design error generated in the battery control unit 30. Further, the hard filter error and the LIBIC error are the respective component guarantee accuracy.

Reference Signs List 1 vehicle 2 battery device 3 notification unit 10 battery 11 unit cell 30 battery control unit 31a equalization circuit (equalization unit)
31b Voltage detection circuit (voltage detection unit)
31d Failure diagnosis circuit (failure diagnosis unit)

Claims (3)

A battery device comprising: a battery having a plurality of unit cells connected to each other; and a battery control unit configured to control charging and discharging of the battery,
The battery control unit includes:
A voltage detection unit that detects voltages of the plurality of unit cells,
An equalizing unit that equalizes the voltage of the plurality of unit cells or a charging rate based on the voltage,
A failure diagnosis unit that detects a failure of the battery control unit;
With
When the failure diagnosis unit detects a failure, the battery control unit estimates an error deterioration amount of a detection result of the voltage detection unit during equalization based on the type of the detected failure, and the estimated value is estimated. The battery device , wherein the equalization by the equalizing unit is stopped when the error deterioration amount is equal to or more than a threshold value . When the failure diagnosis unit detects a failure, the battery control unit estimates an error deterioration amount of a detection result of the voltage detection unit when equalization is stopped based on the type of the detected failure, The battery device according to claim 1 , wherein charging and discharging of the battery are stopped when the estimated error deterioration amount is equal to or larger than the threshold. A battery device according to claim 1 or 2 ,
A notifying unit that notifies an occupant of the vehicle of a detection result of the failure by the failure diagnosis unit,
A vehicle comprising:

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