JP5187234B2 - Overcharge detection device for in-vehicle secondary battery - Google Patents

Description

  The present invention relates to an in-vehicle secondary battery overcharge detection device, and more specifically to an overcharge detection device having a self-diagnosis function.

  Conventionally, an electric vehicle such as an electric vehicle or a hybrid vehicle that travels using stored electric power of an in-vehicle secondary battery (hereinafter also referred to as a battery) has been used. As an in-vehicle secondary battery, a nickel metal hydride battery or a lithium ion battery has been practically used or studied. In particular, in a lithium ion battery, since it is necessary to strictly avoid overcharge, a battery overcharge detection circuit is provided.

  For example, Japanese Unexamined Patent Application Publication No. 2003-079059 (Patent Document 1) describes an in-vehicle assembled battery control device provided with overcharge detection means for detecting overcharge of each cell for each battery cell. In particular, in Patent Document 1, a plurality of comparison units that compare the voltage of each cell and a predetermined reference value for each cell are provided, and the reference value in each comparison unit is compared with the first threshold value for high-level determination and the intermediate value. A configuration capable of switching between the second threshold value for low level determination is described.

  Japanese Patent Application Laid-Open No. 2004-248406 (Patent Document 2) and Japanese Patent No. 4118035 (Patent Document 3) describe changing charging / discharging control of an in-vehicle secondary battery when an overcharged state is detected. Yes. Japanese Patent Application Laid-Open No. 2000-175306 (Patent Document 4) also describes control for correcting charge / discharge control so as to restore the charge / discharge balance of the power storage device. Alternatively, in Japanese Patent Application Laid-Open No. 2007-171044 (Patent Document 5), in order to suppress a decrease in SOC (State Of Charge) calculation accuracy, it is based on estimated SOC based on current integration and charge / discharge history of the secondary battery. It is described that when the error from the estimated SOC becomes large, the SOC estimation accuracy is improved by performing charge / discharge control so as to increase the fluctuation range of the SOC.

Japanese Patent Laid-Open No. 2003-079059 JP 2004-248406 A Japanese Patent No. 4118035 JP 2000-175306 A JP 2007-171044 A

  In recent years, it has been attempted to apply a lithium ion battery to an in-vehicle secondary battery of a hybrid vehicle from the viewpoint of battery performance. On the other hand, for lithium ion batteries, the importance of strictly avoiding overcharging is well known due to the heat generation characteristics during overcharging. For this reason, as described in Patent Document 1, it is preferable to apply an overcharge detection circuit for each battery cell.

  On the other hand, since there may be a case where a characteristic deviation or the like occurs in the overcharge detection circuit itself, it is necessary to appropriately execute self-diagnosis of the overcharge detection circuit in order to accurately detect overcharge. is there. In other words, if this opportunity for self-diagnosis cannot be ensured appropriately, overcharge of the secondary battery may be missed.

  The present invention has been made to solve such problems, and the object of the present invention is to provide an opportunity for self-diagnosis for detecting an abnormality of an overcharge detection device provided in an in-vehicle secondary battery. It is to increase the certainty of overcharge detection by ensuring adequately.

  An overcharge detection device for an in-vehicle secondary battery according to the present invention is an overcharge detection device for an in-vehicle secondary battery that is charge / discharge controlled according to a charge control target value during operation of the vehicle, the first overvoltage detection circuit, A second overvoltage detection circuit and a self-diagnosis unit are provided. The first overvoltage detection circuit is configured to detect overcharge of the secondary voltage. The second overvoltage detection circuit is provided in parallel with the first overvoltage detection circuit, and is configured to detect overcharge of the secondary voltage. The self-diagnosis unit is configured to execute a self-diagnosis for detecting an abnormality in the first and second overvoltage detection circuits at the end of driving of the vehicle. The self-diagnosis unit includes a diagnosis start determination unit and a request change unit. The diagnosis start determination unit instructs the execution of the self-diagnosis on the condition that the voltage of the secondary battery is within a predetermined voltage range in which the first and second overvoltage detection circuits can be self-diagnosed when self-diagnosis is requested. Configured as follows. When the diagnosis start determination unit determines that the voltage of the secondary battery is lower than the predetermined voltage range by the diagnosis start determination unit, the request change unit sets the charge control target value during the next vehicle operation from the current value. Request to change higher.

  According to the above-described on-vehicle secondary battery overcharge detection device, in the overcharge detection device in which the first and second overvoltage detection circuits capable of self-diagnosis within a predetermined voltage range are provided in the secondary battery, When the battery voltage at the time of diagnosis request (typically at the end of vehicle operation) is outside the predetermined voltage range where self-diagnosis is possible, the next operation is performed by changing the charge control target value higher than the current value. The battery voltage at the end can be within the predetermined voltage range where self-diagnosis is possible.

  As a result, unlike a normal hybrid vehicle that normally maintains the SOC at about 50 to 60% of full charge during driving, the power is used up at the end of driving to mount a secondary battery that can be charged by a power source outside the vehicle. Even in a so-called plug-in type hybrid vehicle that aims at such traveling control, it is possible to improve the reliability of overcharge detection by appropriately securing an opportunity for self-diagnosis of the overvoltage charging device. Furthermore, without incurring a cost increase due to the expansion of a predetermined voltage range capable of self-diagnosis, a normal hybrid vehicle (the operation is completed when the SOC target is 50 to 60%) and a plug-in type hybrid vehicle (the operation is performed near the SOC lower limit). It is also possible to provide an overvoltage detection device that can be used universally.

  Preferably, the first overvoltage detection circuit is configured to output a first divided voltage obtained by dividing the voltage of the secondary battery according to a first voltage division ratio that can be variably controlled within a predetermined range. A first voltage dividing unit; and a first voltage comparing unit configured to output a comparison result between the first divided voltage and a predetermined voltage. The second overvoltage detection circuit is configured to output a second divided voltage obtained by dividing the voltage of the secondary battery according to a second voltage division ratio that can be variably controlled within a predetermined range. A voltage dividing unit; and a second voltage comparing unit configured to output a comparison result between the second divided voltage and the predetermined voltage. The self-diagnosis unit further includes a diagnosis control unit and an abnormality determination unit. The diagnosis control unit is configured to control the first and second voltage dividing units so as to change the first and second voltage dividing ratios in a synchronized manner when the self-diagnosis is executed. The abnormality determination unit is configured to determine whether or not the outputs of the first and second voltage comparison units match when the first and second voltage dividing units are controlled by the diagnosis control unit. The

  More preferably, the first and second voltage division ratios are fixedly controlled to different values for detecting the overvoltage of the secondary battery during normal operation except during execution of self-diagnosis.

  In this way, the self-diagnosis can be easily executed by the output comparison in a state where the voltage dividing ratio in each of the first and second overvoltage detection circuits is synchronized and changed stepwise. In particular, during normal operation other than during the execution of self-diagnosis, the overvoltage detection device can be efficiently configured by detecting different levels of overcharge with the duplicated first and second overvoltage detection circuits.

  More preferably, during normal operation, the first voltage division ratio is set higher than the second voltage division ratio. The vehicle performs charge / discharge control so as to prohibit charging of the secondary battery when the first overvoltage detection circuit detects that the first divided voltage is higher than the predetermined voltage. When the second overvoltage detection circuit detects that the second divided voltage is higher than the predetermined voltage, the charging path to the secondary battery is cut off by the switch.

  In this way, it is possible to cope with an abnormal situation by properly using the mechanical interruption of the charging path of the secondary battery and the prohibition of charging of the secondary battery by the control according to the level of overcharge.

  Preferably, the secondary battery is configured by an assembled battery including a plurality of battery blocks having N (N: an integer of 2 or more) battery cells connected in series, and the overcharge detection device corresponds to each battery cell. Provided. Then, the diagnosis start determination unit determines whether or not the voltage obtained by dividing the detection value by the voltage detector arranged corresponding to each battery block by N is within a predetermined voltage range.

  In this way, a practical configuration that can reliably detect overcharge of each battery cell can be realized without significantly increasing the number of voltage detectors arranged in the in-vehicle secondary battery provided as an assembled battery. .

  Preferably, the change request unit accumulates a predetermined number of times, and when the diagnosis start determination unit determines that the voltage of the secondary battery at the time of the self-diagnosis request is lower than the predetermined voltage range, Request to change the charge control target value during operation.

  In this way, it is possible to prevent the charge control target during vehicle operation from being corrected unnecessarily due to word detection.

  Alternatively, preferably, the secondary battery is configured by a lithium ion battery configured to be rechargeable by a power source external to the vehicle.

  In this way, overcharging can be reliably detected by appropriately securing an opportunity for self-diagnosis of overcharge detection devices provided for lithium-ion batteries that require strict prevention of overcharging. It becomes possible to do.

  ADVANTAGE OF THE INVENTION According to this invention, the reliability of overcharge detection can be improved by ensuring the opportunity of the self-diagnosis for the abnormality detection of the overcharge detection apparatus provided in the vehicle-mounted secondary battery appropriately.

It is a block diagram explaining the schematic structure of the hybrid vehicle to which the overcharge detection apparatus of the vehicle-mounted secondary battery by embodiment of this invention is applied. It is a functional block diagram explaining the vehicle control by power management ECU100 shown in FIG. It is a functional block diagram explaining the structure of the overcharge detection apparatus of the vehicle-mounted secondary battery by this Embodiment. It is a circuit diagram explaining the structure of the overcharge detection mechanism shown in FIG. FIG. 5 is a conceptual diagram for explaining the operation of the overvoltage detection circuit shown in FIG. 4. It is a conceptual diagram explaining the result of the self-diagnosis of the overvoltage detection apparatus at the time of normal. It is a conceptual diagram explaining the result of the self-diagnosis of the overvoltage detection apparatus at the time of abnormality occurrence. It is a wave form diagram explaining SOC transition in a plug-in type hybrid vehicle. It is a conceptual diagram explaining the example in which the self-diagnosis of the overvoltage detection apparatus in a plug-in type hybrid vehicle becomes impossible. It is a functional block diagram explaining the structure of the self-diagnosis part shown in FIG. It is a wave form diagram explaining SOC transition of a plug-in type hybrid vehicle when an SOC target value is corrected. It is a flowchart explaining the process sequence of the self-diagnosis by the overcharge detection apparatus of the vehicle-mounted secondary battery by embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a block diagram illustrating a schematic configuration of a hybrid vehicle to which an in-vehicle secondary battery overcharge detection device according to an embodiment of the present invention is applied.

  Referring to FIG. 1, hybrid vehicle 5 includes a main battery 10 constituted by a secondary battery, system main relays 22 and 24, a power control unit (PCU) 30, motor generators 41 and 42, and an engine 50. A power split mechanism 60, a drive shaft 70, and wheels 80.

  The main battery 10 is composed of a secondary battery such as nickel metal hydride or lithium ion. As will be apparent from the following description, the present invention is preferably applied to a secondary battery that is required to reliably detect overcharge, for example, a lithium ion battery.

  The main battery 10 may be configured to be chargeable by an external power source (external power source) of the hybrid vehicle 5 by an external charging configuration (not shown). Typically, the main battery 10 is charged by the external power source by connecting a commercial power source outside the vehicle and a charging inlet (not shown) using a charging cable (not shown). Alternatively, the external power supply and the vehicle are electromagnetically coupled in a non-contact manner to supply electric power, specifically, the primary coil is provided on the external power supply side, the secondary coil is provided on the vehicle side, and the primary coil External charging can also be realized by a configuration in which power is supplied using mutual inductance with the secondary coil.

  Hereinafter, in the present embodiment, the hybrid vehicle in which the main battery 10 is configured to be externally chargeable will be collectively referred to as “plug-in type” regardless of the external charging configuration. That is, the hybrid vehicle 5 shown in FIG. 1 can be a plug-in type.

  The engine 50 is configured to output kinetic energy by the combustion energy of fuel. Power split device 60 is connected to motor generators 41 and 42 and the output shaft of engine 50, and is configured to be able to drive drive shaft 70 by the output of motor generator 42 and / or engine 50. The wheels 80 are rotated by the drive shaft 70. Thus, the hybrid vehicle 5 is configured to be able to travel by the output of the engine 50 and / or the motor generator 42.

  Although the motor generators 41 and 42 can function as both a generator and an electric motor, the motor generator 41 mainly operates as a generator, and the motor generator 42 mainly operates as an electric motor.

  Specifically, the motor generator 41 is used as a starter that starts the engine 50 when an engine start request is made, such as during acceleration. At this time, the motor generator 41 receives power supply from the main battery 10 via the PCU 30 and is driven as an electric motor to crank and start the engine. Further, after the engine 50 is started, the motor generator 41 is rotated by the engine output transmitted through the power split mechanism 60 and can generate electric power.

  Motor generator 42 is driven by at least one of the electric power stored in main battery 10 and the electric power generated by motor generator 41. The driving force of the motor generator 42 is transmitted to the driving shaft 70. Thereby, the motor generator 42 assists the engine 50 to travel the hybrid vehicle 5 or causes the hybrid vehicle 5 to travel only by its own driving force.

  Further, at the time of regenerative braking of the hybrid vehicle 5, the motor generator 42 operates as a generator by being driven by the rotational force of the wheels. At this time, the regenerative power generated by the motor generator 42 is charged into the main battery 10 via the PCU 30.

  PCU 30 performs bidirectional power conversion between main battery 10 and motor generators 41 and 42, and motor generators 41 and 42 operate according to their operation command values (typically torque command values). Control the power conversion. For example, the PCU 30 converts DC power from the main battery 10 into AC power and applies it to the motor generator 41, and converts the DC power from the main battery 10 into AC power to the motor generator 42. And an inverter (not shown) to be applied. These inverters are configured such that the regenerative power generated by the motor generators 41 and 42 can be converted into DC power and output as charging power for the main battery 10.

  The system main relays 22 and 24 are inserted and connected between the PCU 30 and the main battery 10. The system main relays 22 and 24 are turned on / off in response to the relay control signal SE. When the system main relays 22 and 24 are turned off (opened), the charge / discharge path of the main battery 10 is mechanically interrupted.

  The hybrid vehicle 5 further includes a battery monitoring unit 20 for monitoring the main battery 10, a power management ECU (Electronic Control Unit) 100, and an MG (Motor Generator) ECU 110.

  The battery monitoring unit 20 outputs a value indicating the battery state of the main battery 10 to the power management ECU 100 based on the outputs of the temperature sensor 12, the voltage sensor 14 and the current sensor 16 provided in the main battery 10. As will be described later, the battery monitoring unit 20 incorporates an overcharge detection mechanism, and the output of the overcharge detection mechanism is also output to the power management ECU 100.

  Note that the temperature sensor 12, the voltage sensor 14, and the current sensor 16 comprehensively indicate the temperature sensor, the voltage sensor, and the current sensor provided in the main battery 10. That is, in practice, at least a part of the temperature sensor 12, the voltage sensor 14, and the current sensor 16 will be described in detail in terms of being generally provided.

  The power management ECU 100 controls the entire hybrid vehicle 5 through the output distribution between the engine 50 and the motor generators 41 and 42 for the hybrid vehicle 5 to output the traveling power according to the driver's operation (pedal operation or the like). Configured to manage the power balance. Then, power management ECU 100 sets torque request values for motor generators 41 and 42 based on the output distribution determined based on such power balance management. The MGECU 110 controls power conversion by the PCU 30 so that the motor generators 41 and 42 operate according to the torque request value. Specifically, the voltage applied to motor generators 41 and 42 by an inverter (not shown) built in PCU 30 is controlled by MGECU 110.

  Each ECU is composed of a CPU (Central Processing Unit) (not shown) and an electronic control unit with a built-in memory. Based on a map and a program stored in the memory, each ECU performs a calculation process using a detection value by each sensor. Configured to do. Alternatively, at least a part of the ECU may be configured to execute predetermined numerical / logical operation processing by hardware such as an electronic circuit. In FIG. 1, the power management ECU 100 and the MGECU 110 are described as separate elements, but a configuration may be adopted in which both ECUs are integrated and a single ECU is applied.

  FIG. 2 is a functional block diagram illustrating vehicle control by power management ECU 100 shown in FIG.

  Referring to FIG. 2, power management ECU 100 includes a battery control unit 102, a travel control unit 104, and a system control unit 106. Each block in the functional block diagram described below including FIG. 2 can be appropriately executed by software or hardware processing by each ECU.

  Referring to FIG. 2, battery control unit 102 includes battery temperature Tb, battery current Ib and battery voltage Vb based on detection values of temperature sensor 12, voltage sensor 14 and current sensor 16, and an overvoltage detection circuit (not shown). ) From the battery monitoring unit 20.

  The battery control unit 102 indicates the SOC indicating the overall remaining capacity of the main battery 10 and the charge / discharge power upper limit value of the main battery 10 based on the battery temperature Tb, the battery current Ib, and the battery voltage Vb indicating the battery state. And the SOC target value SOCr corresponding to the control center value of the SOC during vehicle operation.

  Furthermore, the battery control unit 102 generates control signals SDV1 and SDV2 for controlling the above-described overvoltage detection circuit. As will be described later, the control signals SDV1 and SDV2 are used at the time of abnormality detection (self-diagnosis) of the overvoltage detection circuit. Further, based on the detection signals S1 and S2 from the overvoltage detection circuit, a failsafe request is issued to the system control unit 106 when overcharge of the main battery 10 is detected.

  The system control unit 106 has a function of controlling the entire system of the hybrid vehicle 5. As a function related to the embodiment of the present invention, the system control unit 106 responds to a fail-safe request from the battery control unit 102 to relay the system main relays 22 and 24 shown in FIG. A signal SE is generated.

  The traveling control unit 104 calculates a vehicle driving force and a vehicle braking force necessary for the entire hybrid vehicle 5 based on the accelerator operation and the brake operation by the driver. The travel control unit 104 restricts the main battery 10 to be charged / discharged within the chargeable / dischargeable range (Win to Wout) of the main battery 10, and then requests the requested vehicle driving force or vehicle. MG request values for the motor generators 41 and 42 and output request values for the engine 50 are generated so as to satisfy the braking force. Engine 50 is controlled to operate according to the output request value by an engine ECU (not shown).

  Further, the MG request value is sent to MGECU 110 shown in FIG. 1, and MGECU 110 controls PCU 30 (FIG. 1) so that motor generators 41 and 42 operate according to the MG request value (typically, torque command value). .

  Note that the SOC target value SOCr is also reflected in the generation of the MG request value and the engine request value in the travel control unit 104. Specifically, when the SOC is higher than the SOCr, the output of the engine 50 is suppressed or stopped, and the MG request value and the engine request value are set so that the vehicle travels actively using the power of the main battery 10. Generated. In this case, the operation of the engine 50 is relatively suppressed.

  Further, when the SOC is lower than the SOCr, the MG request value and the engine request value are generated so that the main battery 10 is charged by the generated power of the motor generator 41 using the engine output. In this case, the engine 50 is relatively easily started. Thus, charging / discharging of main battery 10 during vehicle operation is controlled according to SOC target value SOCr.

  Thus, since the SOC change of the main battery 10 during the operation of the hybrid vehicle 5 is controlled according to the SOC target value SOCr, the SOC at the end of the operation of the hybrid vehicle 5 becomes a value near the SOCr. As is well known, since the secondary battery voltage changes according to the SOC, it is understood that the battery voltage at the end of the operation can be controlled to some extent by setting the SOCr.

Next, the configuration of the overcharge detection device for an in-vehicle secondary battery according to the present embodiment will be described.
With reference to FIG. 3, the main battery 10 shown in FIG. 1 includes a plurality of battery blocks 11. Each battery block 11 is configured by N (N: an integer of 2 or more) battery cells connected in series. FIG. 3 exemplifies a configuration in which one battery block is configured by eight battery cells 10 #, that is, N = 8.

  Voltage sensor 14 is provided for each battery block 11 and detects an output voltage Vbb from N battery cells 10 # belonging to the same battery block 11. Hereinafter, the battery voltage Vbb for each battery block 11 is also referred to as a block voltage Vbb.

  Battery monitoring unit 20 (FIG. 1) has an overcharge detection mechanism 200 provided corresponding to each battery cell 10 #. Although the detailed configuration will be described later, the overcharge detection mechanism 200 has an overvoltage generation circuit provided as a dual system, and detection signals S1 and S2 are output from each overcharge detection mechanism.

  The battery control unit 102 includes a self-diagnosis unit 250 and an overcharge detection unit 260. Self-diagnosis unit 250 and overcharge detection unit 260 represent functional part 102 # related to the overcharge detection of main battery 10 and its self-diagnosis function in battery control unit 102 (FIG. 2). The overcharge detection unit 260 receives the detection signals S1 and S2 related to the battery cells 10 # in the same battery block 11 and generates overcharge detection signals Foc1 and Foc2.

  Basically, the present embodiment is provided with a self-diagnosis function by an overcharge detection mechanism 200 corresponding to each battery cell 10 # and a self-diagnosis unit 250 for diagnosing abnormality of each overcharge detection mechanism 200. An overcharge detection device for an in-vehicle secondary battery is configured. The self-diagnosis unit 250 executes a self-diagnosis of the overcharge detection device in response to a self-diagnosis trigger TRG generated when a self-diagnosis execution request is made. For example, the self-diagnosis trigger TRG is generated in response to turning off of a switch (IG switch or power switch) instructing start / end of vehicle operation when the hybrid vehicle 5 is ended. Furthermore, the self-diagnosis unit 250 generates a signal Fsc indicating the diagnosis result when executing the self-diagnosis.

Furthermore, the structure of the overcharge detection mechanism 200 is demonstrated in detail using FIG.
Referring to FIG. 4, overcharge detection mechanism 200 has overvoltage detection circuits 200A and 200B provided in parallel corresponding to each battery cell 10 #.

  Overvoltage detection circuit 200A includes a voltage dividing unit 202A and a voltage comparison unit 206A. The voltage dividing unit 202A includes a voltage dividing resistor 203A and a voltage dividing ratio control unit 204A. Voltage dividing resistor 203A includes a plurality of resistance elements connected in series between positive electrode Np and negative electrode Nn of battery cell 10 #. The voltage division ratio control unit 204A includes switch elements SW0 to SWk respectively connected between a connection node between a plurality of resistance elements of the voltage dividing resistor 203A and a node Na that outputs a divided voltage. Any one of the switch elements SW0 to SWk is selectively turned on according to the control signal SDV1.

  The voltage comparison unit 206A compares a predetermined reference voltage Vref with the divided voltage output to the node Na, turns on the detection signal S1 when the divided voltage is higher than the reference voltage Vref, and detects otherwise. The signal S1 is turned off.

  By switching on switching elements SW0 to SWk in accordance with control signal SDV1, voltage dividing ratio in voltage dividing unit 202A, that is, the ratio of divided voltage to output voltage (cell voltage) Vc of battery cell 10 # (divided voltage) / Cell voltage) can be variably controlled. By switching the voltage dividing ratio in this way, it is possible to change the comparison voltage that is substantially compared with the cell voltage Vc by the voltage comparison unit 206A while fixing the reference voltage Vref.

  For example, as shown in FIG. 5, in normal times other than during self-diagnosis, the detection signal S1 is turned on when Vc> V (k), while the detection signal S1 is set when Vc ≦ V (k). The voltage dividing ratio of the voltage dividing unit 202A is set so as to be turned off. Specifically, the voltage dividing unit 202A is designed so that the voltage dividing ratio is realized in a state where the switch element SWk is selectively turned on by the control signal SDV1.

  When the switch elements SW0, SW1, SW2,... Are turned on in place of the switch elements SWk, the detection signal S1 becomes the cell voltage Vc and the voltages V (0), V (1), V (2). The voltage dividing section 202A is designed so that a voltage dividing ratio that compares the heights of the two and the other is realized. For example, when the switch element SW0 is selectively turned on by the control signal SDV1, the detection signal S1 is turned on when Vc> V (1), while the detection signal S1 is turned on when Vc ≦ V (1). Turned off.

  As illustrated in FIG. 5, when the switch element is turned on, the detection signal S1 is compared with the comparison voltages V (0), V (1),..., V (k−1), V (k ) And the cell voltage Vc, the voltage dividing unit 202A is designed so as to sequentially show the comparison results. As a result, at the time of self-diagnosis of the overcharge detection device, the switch element SWk is turned off, while any of the other switches is turned on to change the cell voltage Vc to the comparison voltages V (0) to V ( k-1).

  Referring to FIG. 4 again, overvoltage detection circuit 200B is basically configured in the same manner as overvoltage detection circuit 200A, and includes a voltage dividing unit 202B and a voltage comparison unit 206B. The voltage dividing unit 202B includes a voltage dividing resistor 203B and a voltage dividing ratio control unit 204B. Similarly to voltage dividing resistor 203B, voltage dividing resistor 203A is configured by a plurality of resistance elements connected in series between positive electrode Np and negative electrode Nn of battery cell 10 #.

  The voltage division ratio control unit 204B includes switch elements SW0 to SWk and Sn that are respectively connected between a connection node between a plurality of resistance elements of the voltage dividing resistor 203B and a node Nb that outputs a divided voltage. Any one of the switch elements SW0 to SWk and SWn is selectively turned on according to the control signal SDV2.

  The voltage dividing unit 202B is different in the range of the voltage dividing ratio from the voltage dividing unit 202A. When the switch element SWn is turned on, as shown in FIG. 5, the detection signal S2 is V (n) higher than the voltage V (k). And a comparison result of the cell voltage Vc. On the other hand, when each of the switch elements SW0 to SWk is turned on, the detection signal S2 indicates a comparison result between the comparison voltages V (0) to V (k) and the cell voltage Vc, similarly to the detection signal S1.

  As described above, overvoltage detection circuits 200A and 200B are provided so as to form a dual system in parallel with common battery cell 10 #. Further, as shown in FIG. 5, in the normal state, the detection signal S1 from the overvoltage detection circuit 200A can detect overcharge at the level of the cell voltage Vc> V (k), and the detection signal S2 from the overvoltage detection circuit 200B. Can detect a severe overcharge at the level of cell voltage Vc> V (n). Then, overcharge detection unit 260 shown in FIG. 3 detects overcharge when detection signal S1 is turned on in any of battery cells 10 # based on detection signals S1 and S2 from each overcharge detection mechanism 200. The signal Foc1 is turned on, and the overcharge detection signal Foc2 is turned on when the detection signal S2 is turned on in any of the battery cells 10 #.

  For example, the upper limit voltage V (k) for turning on the detection signal S1 can be determined corresponding to the lower limit voltage of the lithium deposition region in the lithium ion battery. At this time, charge / discharge control is performed in response to turning on of the overcharge detection signal Foc1 so as to prohibit charging while the vehicle is traveling (Win = 0).

  Further, the maximum upper limit voltage V (n) for turning on the detection signal S2 can be set in correspondence with the lower limit voltage of the heat generation region of the lithium ion battery. At this time, in response to turning on of the overcharge detection signal Foc2, the system main relays 22 and 24 shown in FIG. 1 are shut off, and a fail-safe request is made to mechanically cut off the charging path to the main battery 10. Output from the battery control unit 102 to the system control unit 106.

  However, if an error occurs in the characteristics of the overvoltage detection circuits 200A and 200B, an error may occur in the overvoltage detection. For example, the voltage range that can be detected by switching the switch elements SW0 to SWk is changed to the original V (0) to V (( There is concern that an offset may occur that shifts from k) to the low voltage side or the high voltage side. When such an offset occurs, the overvoltage detection circuit 200A and / or 200B overlooks the overvoltage that should be detected or the battery behavior (and thus the vehicle behavior) is unnecessarily limited due to erroneous detection of the overvoltage. May occur.

  Therefore, the self-diagnosis of the overvoltage detection device for detecting the abnormalities of the overvoltage detection circuits 200A and 200B as described above is executed as follows.

  FIG. 6 shows a self-diagnosis result when there is no characteristic deviation (offset) between the overvoltage detection circuits 200A and 200B and both are operating normally.

  At the time of self-diagnosis, the control signals SDV1 and SDV2 are generated so as to selectively turn on the same switch elements among the switch elements SW0 to SWk in synchronization with the overvoltage detection circuits 200A and 200B. Thereby, the voltage dividing ratio of the voltage dividing sections 202A and 202B is changed in a stepwise manner in synchronization. As a result, the overvoltage detection circuits 200A and 200B can sequentially compare the cell voltage Vc and the comparison voltages V (0) to V (k) in parallel at the same time.

  As shown in FIG. 6, when there is no characteristic deviation between the overvoltage detection circuits 200A and 200B, the voltage division ratio is changed stepwise, and the comparison voltage with the cell voltage Vc is changed from V (k). In the process of sequentially decreasing, the detection signal S1 of the overvoltage detection circuit 200A and the detection signal S2 of the overvoltage detection circuit 200B change from off to on at the same timing. In the example of FIG. 6, in the configuration in which the voltage dividing ratio of 8 steps can be switched in total, the detection signals S <b> 1 and S <b> 2 are switched from OFF to ON at the time of changing in 3 steps. That is, when the detection signals S1 and S2 always coincide, there is no characteristic deviation between the overvoltage detection circuits 200A and 200B, and a self-diagnosis result that is normal can be obtained.

  On the other hand, FIG. 7A shows the self-diagnosis result when the characteristics of the overvoltage detection circuit 200B are shifted to the high voltage side, and FIG. 7B shows the characteristics of the overvoltage detection circuit 200B being high. The self-diagnosis result when the voltage is shifted is shown.

  In these cases, it can be understood that when the control signals SDV1 and SDV2 are set and the self-diagnosis is performed in the same manner as described in FIG. 6, a period in which the detection signals S1 and S2 do not coincide with each other occurs. That is, in the process of changing the voltage division ratio so that the comparison voltage with the actual cell voltage Vc is sequentially decreased from V (k), in the case of FIG. 7A, the detection signal S1 is on while the detection signal S2 is on. 7 is turned off, and in the case of FIG. 7B, the detection signal S1 is turned off while the detection signal S2 is turned on.

  When these phenomena occur, it is detected that the signal Fsc shown in FIG. 3 is turned on, a characteristic deviation occurs between the overvoltage detection circuits 200A and 200B, and accurate overvoltage detection may not be performed. The

  Referring to FIG. 5 again, in view of the contents of the self-diagnosis described with reference to FIGS. 6 and 7, the voltage range corresponding to the voltage division ratio range in which the cell voltage Vc can be changed step by step as the self-diagnosis execution condition. It is understood that it is at least necessary to be inside V (0) -V (k). Further, in consideration of the point of comparison between the overvoltage detection circuits 200A and 200B, the cell voltage Vc is within the predetermined voltage range 500 of the voltages V (1) to V (k−1) in consideration of measurement errors and the like. It is preferable to enter. In other words, if the cell voltage Vc is not within the predetermined voltage range 500 at the self-diagnosis execution timing, the opportunity for self-diagnosis is lost. Hereinafter, the predetermined voltage range 500 is also referred to as a dynamic range 500 that enables self-diagnosis. Note that the voltage range V (0) to V (k) can be used as the dynamic range 500 as it is depending on conditions, such as when the measurement error is at a level that can be completely ignored.

  Typically, at the end of the operation of the hybrid vehicle 5, an opportunity for self-diagnosis of the overvoltage detection device as described above is provided.

  Here, in a normal hybrid vehicle that does not assume charging of the main battery 10 by a power source external to the vehicle, the vehicle can be started only by the motor generator, and the vehicle is driven to have a margin for receiving regenerative power during regenerative braking. The middle SOC target value (SOCr) is set to 50 to 60% of full charge. Therefore, the SOC at the end of the vehicle operation where the self-diagnosis is performed is also substantially the same value.

  On the other hand, unlike a normal hybrid vehicle that cannot be externally charged, the plug-in hybrid vehicle proposed in recent years uses up the power of the main battery 10 at the end of vehicle operation in preparation for external charging after the operation ends. Such traveling control is intended.

  Therefore, as shown in FIG. 8, SOC target value SOCr is set in the vicinity of SOC lower limit value SOCl. For this reason, the SOC at the end of the operation is also a value in the vicinity of the SOCr.

  On the other hand, the SOC range 500 # from SOC1 corresponding to the lower limit voltage V (1) of the dynamic range 500 shown in FIG. 5 to SOC2 corresponding to the upper limit voltage V (k−1) of the dynamic range 500 is overvoltage detection. It becomes the SOC range in which self-diagnosis of the device is possible.

  As shown in FIG. 9, when the actual cell voltage Vc at the time of executing the self-diagnosis becomes too low due to the SOC at the end of the operation of the hybrid vehicle 5 becoming a value in the vicinity of SOCr, the overvoltage detection circuits 200A and 200B Even if the voltage division ratio is changed, both the detection signals S1 and S2 remain off. At this time, even if an abnormality similar to that in FIG. 6A occurs, the detection signals S1 and S2 always coincide with each other, so that an abnormality of the overvoltage detection device cannot be detected. That is, the self-diagnosis cannot be executed correctly.

  On the other hand, when a battery that requires strict overcharge management, such as a lithium ion battery, is applied to the main battery 10, an overcharge detection device (overvoltage detection circuit 200A) is used to increase the reliability of overcharge detection. , 200B) is appropriately secured, and it is preferable to promptly notify the user when the abnormality occurs. This is because if the state as shown in FIG. 9 continues, a detection failure may occur with respect to the occurrence of overcharge in battery cell 10 #.

  On the other hand, in order to widen the voltage range of the dynamic range 500, it is necessary to widen the range in which the voltage division ratio of the overvoltage detection circuits 200A and 200B can be changed. However, as can be understood from the configuration of FIG. 4, the expansion of the range in which the voltage division ratio can be changed causes an increase in the number of switch elements to be arranged, resulting in an increase in cost. That is, from the standpoint of generalization of parts from the viewpoint of manufacturing cost, considering that the overvoltage detection circuits 200A and 200B are shared between the normal hybrid vehicle and the plug-in hybrid vehicle, the range in which the voltage division ratio can be changed is increased. Spreading is not always desirable.

  Therefore, in the embodiment of the present invention, control that can appropriately ensure the opportunity of self-diagnosis of the overvoltage detection device even when applied to a plug-in hybrid vehicle in which the phenomenon described with reference to FIG. 8 is likely to occur. Provide configuration.

10 is a block diagram showing a detailed configuration of the self-diagnosis unit 250 shown in FIG.
Referring to FIG. 10, self-diagnosis unit 250 includes a diagnosis start determination unit 252, a diagnosis control unit 254, a coincidence comparison unit 256, and a change request unit 258.

  Diagnosis start determination unit 252 determines whether cell voltage Vc of battery cell 10 # is within dynamic range 500 where self-diagnosis is possible in response to self-diagnosis trigger TRG in response to the end of operation of hybrid vehicle 5. Specifically, whether or not the self-diagnosis can be started can be determined based on the cell voltage (Vc = Vbb / N) estimated based on the block voltage Vbb of the battery block 11. When the cell voltage is in the dynamic range 500, the signal SJD for instructing execution of self-diagnosis is turned on.

  When the signal SJD is turned on by the diagnosis start determination unit 252, the diagnosis control unit 254 changes the control signals SDV1 and SDV2 stepwise and in common according to a predetermined pattern. As a result, as described with reference to FIGS. 6 and 7, the voltage division ratio in the overvoltage detection circuits 200A and 200B can be changed stepwise.

  The coincidence comparison unit 256 performs coincidence comparison of the detection signals S1 and S2 in the process in which the control signals SDV1 and SDV2 are sequentially changed by the diagnosis control unit 254. When they do not match, the signal Fsc is turned on to indicate that a characteristic deviation has occurred between the overvoltage detection circuits 200A and 200B.

  When the signal Fsc is turned on, a predetermined display for notifying the user of the hybrid vehicle 5 of the occurrence of an abnormality is made and a diagnosis code indicating the content of the abnormality is generated. Further, fail-safe control is performed to limit the charge / discharge range of the main battery 10 as necessary.

  On the other hand, even when the self-diagnosis trigger TRG is generated, when the diagnosis start determination unit 252 does not turn on the signal SJD, that is, when the cell voltage at the time of self-diagnosis execution (at the end of operation) is lower than the dynamic range 500, the change request unit 258 Generates an SOCr change request to the SOC target setting unit 270 that sets the SOC target value SOCr.

  Note that the change request unit 258 may be configured to include a counter 259 that counts the number of times the signal SJD is turned off when the self-diagnosis trigger TRG is generated, and the count number of the counter 259 is a predetermined number (2 Only when the above integer) is reached, the SOC target setting unit 270 may be configured to generate an SOCr change request. In this way, it is possible to prevent an SOCr change request from being generated unnecessarily due to erroneous detection.

  Referring to FIG. 11, when a correction request is generated from change request unit 258, SOC target setting unit 270 sets the SOC target value SOCr during the next vehicle operation to the conventional value (<SOC1) shown in FIG. Accordingly, the SOCr is set to a value higher than normal so that SOCr is set within the SOC range 500 # corresponding to the dynamic range 500.

  Thereby, at the end of the next operation, since the SOC is within SOC range 500 #, the probability that diagnosis start determination unit 252 turns on signal SJD is increased. That is, it is possible to ensure an opportunity for self-diagnosis of the overvoltage detection device.

  In FIG. 12, a self-diagnosis processing procedure by the overcharge detection device for an in-vehicle secondary battery according to the embodiment of the present invention shown in FIG. 10 will be described using a flowchart. Control processing according to the flowchart shown in FIG. 12 is basically realized by executing a program stored in advance in power management ECU 100 at a predetermined cycle. Note that the power management ECU 100 may be configured so that some of the steps illustrated in FIG. 10 are realized by hardware processing.

  Referring to FIG. 12, power management ECU 100 determines whether or not a self-diagnosis trigger has been generated in step S100. When the self-diagnosis trigger is not generated (NO determination in step S100), the subsequent processing is not executed.

  When the self-diagnosis trigger is generated (YES in step S100), the power management ECU 100 determines that the current cell voltage Vc is within the voltage range where self-diagnosis is possible, that is, the dynamic range 500 shown in FIG. Determine if it is inside. That is, the process in step S110 corresponds to the function of the diagnosis start determination unit 252 illustrated in FIG.

  When NO is determined in S110, that is, when the cell voltage is not in the voltage range where self-diagnosis is possible, the power management ECU 100 counts up the cumulative number N (NG) of self-diagnosis impossible in step S140.

  On the other hand, power management ECU 100 executes self-diagnosis by diagnostic control unit 254 shown in FIG. 10 when the cell voltage is within the voltage range where self-diagnosis is possible (when YES is determined in S110). It is determined in step S120 whether or not the processing has ended normally.

  When the self-diagnosis is completed normally, the cumulative number N (NG) of self-diagnosis impossible is cleared to zero. On the other hand, when the self-diagnosis does not end normally for some reason (NO determination in S110), step S130 is stepped and the self-diagnosis impossible cumulative number N (NG) is not cleared.

  Although illustration is omitted, when an abnormality of the overcharge detection device (overvoltage detection circuits 200A, 200B) is detected by the self-diagnosis that has been normally completed, as described above, a notification to the user or the main battery 10 is performed. Measures such as limiting the charge / discharge range are taken.

  Through the processing in steps S110 to S140, the self-diagnosis cumulative number N (NG) missed the opportunity for self-diagnosis because the cell voltage has not entered the dynamic range 500 since the previous self-diagnosis ended normally. This indicates the integrated value of the number of times.

  In step S150, power management ECU 100 compares self-diagnosis cumulative number N (NG) counted up, cleared, or maintained with a predetermined determination number Nth in the current occurrence of self-diagnosis trigger. The number Nth of determinations can be set to any integer with Nth ≧ 1. However, by setting Nth ≧ 2, it is possible to avoid erroneously issuing an SOCr change request due to a measurement error or the like.

  When N (NG) is equal to or greater than the determination count Nth (when YES is determined in step S150), power management ECU 100 generates a request for changing SOC target value SOCr during the next vehicle operation in step S160. To do. As a result, as shown in FIG. 11, SOC target value SOCr is changed to a value different from the normal value so that the SOC at the end of operation enters SOC range 500 # corresponding to dynamic range 500. That is, the processing in steps S150 and S160 corresponds to the function of the change request unit 258 in FIG.

  On the other hand, when N (NG) has not reached the determination number Nth (NO determination in S150), power management ECU 100 performs normal SOCr setting as shown in FIG. 8 in step S170.

  As described above, according to the overcharge detection device for the in-vehicle secondary battery according to the embodiment of the present invention, the characteristic deviation between the overvoltage detection circuits provided in duplicate for the battery cell (secondary battery) is detected. It is possible to control the vehicle so that an opportunity for self-diagnosis can be provided. In addition, overvoltage detection between a normal hybrid vehicle (end of operation when the SOC target is 50 to 60%) and a plug-in type hybrid vehicle (end of operation near the SOC lower limit) without causing an increase in cost related to self-diagnosis. It is also possible to share the apparatus.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to self-diagnosis of overcharge detection of an in-vehicle secondary battery.

  5 hybrid vehicle, 10 main battery, 10 # battery cell, 11 battery block, 12 temperature sensor, 14 voltage sensor, 16 current sensor, 20 battery monitoring unit, 22, 24 system main relay, 41, 42 motor generator, 50 engine, 60 power split mechanism, 70 drive shaft, 80 wheels, 100 power management ECU, 102 battery control unit, 102 # self-diagnosis function part, 104 travel control unit, 106 system control unit, 110 MGECU, 200 overcharge detection mechanism, 200A, 200B overvoltage detection circuit, 202A, 202B voltage dividing unit, 203A, 203B voltage dividing resistor, 204A, 204B voltage division ratio control unit, 206A, 206B voltage comparison unit, 250 self-diagnosis unit, 252 diagnosis start determination unit, 254 diagnosis control unit, 256 match ratio Unit, 258 change request unit, 260 overcharge detection unit, 270 SOC target setting unit, 500 dynamic range, 500 # SOC range (corresponding to dynamic range), Foc1, Foc2 overcharge detection signal, Fsc signal (self-diagnosis result), Ib Battery current, N (NG) Self-diagnosis cumulative number of times, Nth judgment number of times, S1, S2 detection signal (overvoltage detection circuit), SDV1, SDV2 control signal (voltage division ratio), SE relay control signal, SJD signal (whether self-diagnosis can be started) ), SW0 to SWk, SWn switch element, Tb battery temperature, TRG self-diagnosis trigger, V (0) to V (k), V (n) comparison voltage, Vbb block voltage, Vc cell voltage, Vref reference voltage (voltage comparison) Part).

Claims (7)

An overcharge detection device for an in-vehicle secondary battery that is charged and discharged according to a charge control target value during operation of the vehicle,
A first overvoltage detection circuit for detecting overcharge of the secondary voltage;
A second overvoltage detection circuit provided in parallel with the first overvoltage detection circuit for detecting overcharge of the secondary voltage;
A self-diagnosis unit configured to perform a self-diagnosis for detecting an abnormality in the first and second overvoltage detection circuits at the end of driving of the vehicle;
The self-diagnosis unit
When the self-diagnosis is requested, the execution of the self-diagnosis is instructed on the condition that the voltage of the secondary battery is within a predetermined voltage range in which the first and second overvoltage detection circuits can self-diagnose. A diagnosis start determination unit configured in
When the diagnosis start determination unit determines that the voltage of the secondary battery at the time of the self-diagnosis request is lower than the predetermined voltage range, the charge control target value during the next vehicle operation is set from the current value. And an overcharge detection device for an in-vehicle secondary battery, including a change request unit that requests to change the height of the battery. The first overvoltage detection circuit includes:
A first voltage dividing section configured to output a first divided voltage obtained by dividing the voltage of the secondary battery according to a first voltage dividing ratio that can be variably controlled within a predetermined range;
A first voltage comparator configured to output a comparison result between the first divided voltage and a predetermined voltage;
The second overvoltage detection circuit includes:
A second voltage dividing section configured to output a second divided voltage obtained by dividing the voltage of the secondary battery according to a second voltage dividing ratio that can be variably controlled within a predetermined range;
A second voltage comparison unit configured to output a comparison result between the second divided voltage and the predetermined voltage;
The self-diagnosis unit
A diagnostic control unit configured to control the first and second voltage dividing units so as to change the first and second voltage dividing ratios in a synchronized manner in a stepwise manner during the execution of the self-diagnosis. When,
When the first and second voltage dividers are controlled by the diagnostic controller, it is configured to determine whether or not the outputs of the first and second voltage comparators match. The overcharge detection device for an in-vehicle secondary battery according to claim 1, further comprising an abnormality determination unit.   3. The first and second voltage division ratios are fixedly controlled to different values for detecting an overvoltage of the secondary battery in a normal operation except during the execution of the self-diagnosis. Overcharge detection device for in-vehicle secondary batteries. In the normal operation, the first voltage division ratio is higher than the second voltage division ratio;
The vehicle is
While the first overvoltage detection circuit detects that the first divided voltage is higher than the predetermined voltage, the charge / discharge control is performed so as to prohibit charging of the secondary battery. When the second overvoltage detection circuit detects that the second divided voltage is higher than the predetermined voltage, the switch is configured to cut off a charging path to the secondary battery by a switch. The overcharge detection device for an in-vehicle secondary battery according to claim 3. The secondary battery is constituted by an assembled battery including a plurality of battery blocks having N (N: an integer of 2 or more) battery cells connected in series,
The overcharge detection device is provided corresponding to each of the battery cells,
The diagnosis start determination unit determines whether or not a voltage obtained by dividing a detection value by a voltage detector arranged corresponding to each battery block by the N is within the predetermined voltage range. The overcharge detection device for an in-vehicle secondary battery according to any one of -4.   The change request unit accumulates a predetermined number of times, and when the diagnosis start determination unit determines that the voltage of the secondary battery at the time of the self-diagnosis request is lower than the predetermined voltage range, The overcharge detection device for an in-vehicle secondary battery according to any one of claims 1 to 5, wherein the charge control target value during driving of the vehicle is requested to be changed.   The overcharge detection device for an in-vehicle secondary battery according to any one of claims 1 to 6, wherein the secondary battery is configured by a lithium ion battery configured to be rechargeable by a power source external to the vehicle.

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