JP5532859B2 - Power supply system and battery abnormality determination method - Google Patents

Description

  The present invention relates to a technology for charging a battery mounted on a vehicle by supplying electric power from a power source external to the vehicle.

  As a conventional technique, there is known a charging device that charges a battery with electric power supplied from an external power source in a state where a vehicle and an external power source are connected by a charging cable (see, for example, Patent Document 1).

JP 2009-071900 A

  By the way, in a vehicle capable of receiving power supply from an external power source, there is a possibility that a short-circuit abnormality may occur in an in-vehicle battery while the external power source is connected to the vehicle. However, there is a high possibility of being unattended while the external power supply is connected to the vehicle (for example, the user may leave the vehicle after connecting the external power supply to the vehicle). When a short circuit abnormality occurs, it is desired to detect the occurrence quickly and take appropriate measures against the short circuit abnormality.

  Therefore, an object of the present invention is to provide a power supply system and a battery abnormality determination method capable of determining a short circuit abnormality of a battery in a short time in a state where an external power supply is connected to the vehicle.

In order to achieve the above object, a power supply system according to the present invention includes:
An in-vehicle first battery;
An in-vehicle second battery;
An output means for outputting a charging current of the first battery by converting the supply power of the second battery and / or an external power source capable of charging the second battery, into a voltage ;
By stopping the output of the output means for a predetermined time during charging of the second battery by the external power source while the external power source is connected to the vehicle, the first battery is discharged. And determining means for determining a short-circuit abnormality of one battery.

In order to achieve the above object, a battery abnormality determination method according to the present invention includes:
The output of the output means for outputting the charging current of the in-vehicle first battery by converting the voltage supplied to the in-vehicle second battery and / or the power supplied from the vehicle external power source capable of charging the second battery, While the power source is connected to the vehicle, the first battery is discharged for a predetermined time while the second battery is being charged by the external power source, and the first battery is discharged to determine a short circuit abnormality of the first battery. It is characterized by doing.

  According to the present invention, a battery short-circuit abnormality can be determined in a short time in a state where an external power source is connected to the vehicle.

1 is a block diagram showing a configuration of a power supply system 10 that is an embodiment of the present invention. It is the flowchart which showed the battery abnormality determination method which is an Example of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a vehicle power supply system 10 according to an embodiment of the present invention. The power supply system 10 is provided in a vehicle equipped with a battery that can be charged from the external power supply 25. Such a vehicle is sometimes referred to as a plug-in vehicle, and specific examples thereof include a plug-in hybrid vehicle, an electric vehicle, and a fuel cell vehicle.

  The power supply system 10 includes a low-voltage battery 1, a high-voltage battery 2, a DC-DC converter 3, and an ECU (Electronic Control Unit) 4 as main components. The low-voltage battery 1 is a secondary battery provided as an in-vehicle first battery. The high-voltage battery 2 is a secondary battery provided as an in-vehicle second battery. The DC-DC converter 3 is an output unit that outputs a charging current for charging the low-voltage battery 1. The ECU 4 stops the output of the DC-DC converter 3 for a predetermined time in a state where the external power source 25 capable of charging the high voltage system battery 2 is connected to the vehicle, thereby discharging the low voltage system battery 1. This is a determination means for determining a short circuit abnormality of the low voltage battery 1 based on the voltage drop of the battery 1.

  As a case different from the power supply system 10, for example, when the low voltage battery 1 is discharged by “decreasing” the output voltage of the DC-DC converter 3, the output from the DC-DC converter 3 is also present. For this reason, the battery voltage of the low-voltage battery 1 is unlikely to decrease. Therefore, it is necessary to increase the time during which the output voltage of the DC-DC converter 3 is “decreased” to cause a voltage drop necessary for determining a short-circuit abnormality of the low-voltage battery 1 (for example, 10 minutes). It takes time to obtain the determination result of the short circuit abnormality of the low-voltage battery 1.

  On the other hand, since the power supply system 10 “stops” the output of the DC-DC converter 3, the low-voltage battery 1 is discharged more reliably than when the output voltage of the DC-DC converter 3 is “decreased”. Therefore, the battery voltage of the low-voltage battery 1 tends to decrease. Therefore, it is not necessary to lengthen the time during which the output of the DC-DC converter 3 is “stopped” in order to secure the time for causing the voltage drop necessary for determining the short circuit abnormality of the low-voltage battery 1. Therefore, if a short circuit abnormality occurs in the low voltage battery 1, the battery voltage of the low voltage battery 1 decreases more quickly than in the case where no short circuit abnormality occurs. In order to generate the voltage drop necessary for the output, the time during which the output of the DC-DC converter 3 is “stopped” can be shortened (for example, 5 seconds). That is, the determination of the short circuit abnormality of the low-voltage battery 1 can be performed in a short time.

  Moreover, according to the power supply system 10, since the discharge time of the low voltage | pressure battery 1 for determining the short circuit abnormality of the low voltage | pressure battery 1 can be shortened, the damage to the low voltage | pressure system battery 1 by discharge can be suppressed. .

  Next, the configuration of FIG. 1 will be described in more detail.

  The low voltage battery 1 supplies power to a low voltage (for example, 12V) electric load 16. The low-voltage battery 1 is discharged by supplying power to the electric load 16. The electric load 16 is operated by at least one of electric power stored in the low-voltage battery 1 and / or electric power supplied from an alternator (not shown). Specific examples of the electric load 16 include auxiliary machines such as an ECU, a sensor, an audio device, and a solenoid valve. The low voltage system battery 1 for supplying power to such an auxiliary machine is also called an auxiliary battery. A specific example is a lead battery.

  The high voltage battery 2 supplies power to a high voltage (for example, 202V) electric load 17. A specific example of the electric load 16 includes a motor (motor / generator (MG)) for driving the vehicle by rotating driving wheels of the vehicle. For example, a plug-in hybrid vehicle including the power supply system 10 travels by driving force from at least one of an engine (not shown) that is an internal combustion engine and the MG. The electric load 17 is operated by at least one of electric power stored in the high-voltage battery 2 and electric power supplied via the charging control unit 5. Specific examples of the high voltage battery 2 include a lithium ion battery and a nickel metal hydride battery.

  The charging control unit 5 converts AC power (for example, AC 100 V, AC 200 V, etc.) supplied from the external power source 25 into DC power, and via the high-voltage power supply path 8, the high-voltage battery 2, the electric load 17, DC A function of a charger for supplying to the DC converter 3 is provided. The charging control unit 5 includes connection information transmitting means for transmitting connection information that can determine whether or not the vehicle and the external power supply 25 are connected to the ECU 4. This connection information transmission means can be realized, for example, by a switch that outputs a signal that changes depending on whether or not the vehicle and the external power supply 25 are connected. In addition, the charging control unit 5 may include charging execution information transmitting means for transmitting charging execution information that can determine whether or not the high-voltage battery 2 is charged by the external power source 25 to the ECU 4. This charging execution information transmission means can be realized by, for example, a switch that outputs a signal that changes depending on whether or not charging of the high-voltage battery 2 by the external power source 25 is performed.

  The charging control unit 5 controls charging of the high voltage battery 2. The charging control unit 5 determines whether or not charging is necessary based on, for example, a battery state such as a voltage value and a charging rate of the high voltage battery 2. When it is detected that the battery state of the high-voltage system battery 2 is a predetermined battery state to stop charging (for example, the voltage value or the charging rate of the high-voltage system battery 2 is greater than or equal to a predetermined value). If detected, power transmission from the external power source 25 is cut off. Thereby, even if the external power supply 25 remains connected to the vehicle via the charging cable 24, the charging of the high-voltage battery 2 can be automatically stopped.

  The charging control unit 5 may include, for example, an inverter that converts AC power from the external power source 25 into DC power, and a converter (regulator) that regulates DC power from the inverter. The inverter may convert AC power generated by an MG (not shown) that generates electric power based on engine power that generates driving driving torque of the vehicle into DC power.

  The charging cable 24 electrically connects the vehicle and the external power source 25, and enables charging from the external power source 25 to the vehicle by fitting with the power receiving side connector 11 attached to the vehicle. The charging cable 24 includes a power feeding side connector 21 that can be fitted to the power receiving side connector 11 of the vehicle body, a plug 23 that can be connected to an external power source 25, and a power feeding line 22 that connects the power feeding side connector 21 and the plug 23. The external power source 25 may be an AC commercial power source (for example, a household outlet) or a charging device provided in a charging facility.

  The DC-DC converter 3 may output the charging current of the low-voltage battery 1 based on the power supplied from the high-voltage battery 2, or based on the power supplied from the external power source 25 via the charging control unit 5. The charging current of the low-voltage system battery 1 may be output, or the charging current of the low-voltage system battery 1 is output based on the supply power of both the high-voltage system battery 2 and the external power source 25 via the charging control unit 5. May be. For example, if the external power supply 25 is not connected to the vehicle, the DC-DC converter 3 can output the charging current of the low-voltage battery 1 based on the power supplied from the high-voltage battery 2. Further, for example, even if the high voltage battery 2 is disconnected from the power supply system 10 for some reason, the DC-DC converter 3 is connected to the low voltage system based on the electric power supplied from the vehicle external power supply 25 via the charge control unit 5. The charging current of the battery 1 can be output.

  The DC-DC converter 3 adjusts the output voltage of the DC-DC converter 3 based on the power supplied from the high-voltage battery 2 and / or the external power supply 25, and outputs the output current corresponding to the adjusted output voltage to the DC-DC. The output from the converter 3 is output toward the low-voltage battery 1. Based on a signal from the ECU 4, the output voltage of the DC-DC converter 3 performs voltage conversion (that is, step-down conversion) of the voltage system power supply voltage on the high voltage system battery 2 side to a power supply voltage that the low voltage system battery 1 can accept. To be adjusted. That is, the DC-DC converter 3 can charge or discharge the low voltage side battery 1 by outputting an output current with an output voltage adjusted according to a command signal from the ECU 4.

  The ECU 4 is an electronic control device that determines a command value (set value) of the output voltage of the DC-DC converter 3 based on a detection signal from the sensor 7 that detects the battery state of the low-voltage battery 1. Specific examples of the sensor 7 include a voltage sensor that detects the battery voltage of the low-voltage battery 1 and a temperature sensor that detects the temperature of the low-voltage battery 1. Further, the ECU 4 performs DC-DC based on connection information that can determine whether or not the vehicle and the external power source 25 are connected and / or charging execution information that can determine whether or not the high-voltage battery 2 is charged by the external power source 25. A command value (set value) of the output voltage of the converter 3 is determined. The ECU 4 detects that the vehicle and the external power source 25 are connected based on the connection information and / or that the charging of the high voltage system battery 2 by the external power source 25 is started based on the charging execution information. In this case, the DC-DC converter 3 is operated, and charging of the low-voltage battery 1 by the DC-DC converter 3 is started as necessary.

  The ECU 4 can stop the output of the DC-DC converter 3 for a predetermined time. For example, the ECU 4 can stop the output of the DC-DC converter 3 for a predetermined time by transmitting a command signal instructing to stop or return the output of the DC-DC converter 3 to the DC-DC converter 3. In this case, the output of the DC-DC converter 3 can be stopped for a predetermined time by repeatedly stopping and returning the voltage conversion operation of the DC-DC converter 3. Further, for example, the ECU 4 relays the output of the DC-DC converter 3 by driving a relay 6 that is a shut-off means capable of shutting off the low-voltage power supply path 9 connecting the DC-DC converter 3 and the low-voltage side battery 1. 6 can be stopped for a predetermined time by repeating the energizing / shut-off operation.

  In addition, the output of the DC-DC converter 3 is stopped intermittently (for example, periodically) while the external power supply 25 is connected to the vehicle, thereby discharging the low-voltage battery 1. Is repeated, and the determination of the short circuit abnormality of the low-voltage battery 1 can be repeatedly performed. As a result, even if a short circuit abnormality occurs in the low voltage battery 1 in a situation where the external power supply 25 is connected to the vehicle and can become unmanned, the short circuit abnormality can be detected promptly and predetermined appropriate measures can be taken. it can. For example, the ECU 4 can transmit warning information such as a warning display, a warning sound, a warning signal, and the like, and can record that a short circuit abnormality has occurred as diagnostic information.

  Further, since the DC-DC converter 3 outputs the charging current of the low-voltage battery 1 based on the power supplied from the high-voltage battery 2 and / or the external power supply 25, the DC-DC converter 3 is charged during the charging of the high-voltage battery 1 by the external power supply 25. By stopping the output of the DC converter 3 for a predetermined time, the amount of power taken out from the high voltage system battery 2 and / or the external power source 25 is reduced, so that the charging time of the high voltage system battery 1 by the external power source 25 can be shortened. .

  Further, as described above, according to the power supply system 10, since the discharge time of the low voltage battery 1 for determining the short circuit abnormality of the low voltage battery 1 can be shortened, the amount of discharge in the discharge time is reduced, and the discharge The supplementary charging time required to compensate the amount by the charging current from the DC-DC converter 3 can also be shortened. As a result, it is possible to prevent the life of the low-voltage battery 1 from being reduced due to repeated charging and discharging.

  Further, the ECU 4 can determine the short circuit abnormality of the low voltage battery 1 based on the battery voltage at the time of discharging the low voltage battery 1. If a short-circuit abnormality has occurred in the low-voltage battery 1, the battery voltage of the low-voltage battery 1 when the low-voltage battery 1 is discharged is compared to the case where no short-circuit abnormality has occurred in the low-voltage battery 1. It is because it is detected low.

  An example of a short circuit abnormality in the low-voltage battery 1 is a short circuit of a cell in the battery. The low-voltage battery 1 is composed of a plurality of cells, and the total voltage of each cell becomes the battery voltage of the low-voltage battery 1. Therefore, when one or more cells in the low-voltage battery 1 are short-circuited, a voltage dropped by the voltage of the shorted cell is detected as the battery voltage of the low-voltage battery 1.

  The short-circuit abnormality of the low-voltage battery 1 may include not only the case of being completely short-circuited but also the case of being short-circuited.

  FIG. 2 is a flowchart showing a battery abnormality determination method according to an embodiment of the present invention. The battery abnormality determination method of the present embodiment is such that the output of the DC-DC converter 3 that outputs the charging current of the low-voltage battery 1 is stopped for a predetermined time in a state where the external power supply 25 is connected to the vehicle, thereby By discharging the battery 1, a short circuit abnormality of the low-voltage battery is determined. The ECU 4 of the power supply system 10 determines a short circuit abnormality of the low voltage battery 1 according to this method.

  In step S10, the vehicle power source 25 is connected to the vehicle while the vehicle is stopped, and charging of the high voltage system battery 2 by the vehicle power source 25 is started.

  In step S <b> 12, the ECU 4 that detects the connection of the external power supply 25 or the start of charging of the high-voltage battery 2 starts the DC-DC converter 3. The DC-DC converter 3 starts charging the low-voltage battery 1 by outputting an output current with an output voltage Vo1 (for example, 14 V) adjusted according to a command signal from the ECU 4. In step S12, the DC-DC converter 3 recovers the discharge of the low-voltage battery 1 before the start of charging after the vehicle travels, so that the voltage Vo1 that can charge the low-voltage battery 1 is charged at the stage of the start of charging. Charge. This is because if the output of the DC-DC converter 3 is stopped in a state where the charging is not sufficiently performed, the voltage drop of the low-voltage battery 1 becomes large, and even a normal battery is erroneously determined as abnormal. .

  As shown in step S14, the DC-DC converter 3 continues charging at the output voltage Vo1 until a predetermined time T1 (for example, 2 minutes) elapses from the start of output at the output voltage Vo1. The time T1 should just be preset to the time which can charge the low voltage | pressure system battery 1 reliably.

  In step S16, after the elapse of time T1, the DC-DC converter 3 stops power generation based on the power supply voltage on the high voltage system battery 2 side, and stops its output. When the output of the DC-DC converter 3 is stopped, the charging current stops flowing to the low voltage battery 1 and the discharge of the low voltage battery 1 is started.

  As shown in step S18, the DC-DC converter 3 continues to stop the output until a predetermined time T2 (for example, 5 seconds) elapses after the output is stopped. The time T2 only needs to be set as short as possible so that at least the time necessary for determining the short-circuit abnormality of the low-voltage battery 1 can be secured while taking into account the responsiveness of the DC-DC converter 3.

  In step S20, the ECU 4 determines whether or not the battery voltage of the low-voltage battery 1 after the elapse of time T2 when the output of the DC-DC converter 3 is stopped is equal to or higher than a predetermined threshold voltage Vth based on the output signal of the sensor 7. Determine whether. The threshold voltage Vth only needs to be set to a voltage (for example, 11.5 V) that can determine the occurrence of a short circuit abnormality in the low-voltage battery 1.

  When the battery voltage of the low voltage battery 1 is equal to or higher than the threshold voltage Vth, the ECU 4 determines that the voltage drop when the output of the DC-DC converter 3 is stopped for the time T2 and the low voltage battery 1 is discharged is small. It is determined that 1 short circuit abnormality has not occurred. On the other hand, when the battery voltage of the low voltage battery 1 is less than the threshold voltage Vth, the ECU 4 determines that the voltage drop when the output of the DC-DC converter 3 is stopped for the time T2 and the low voltage battery 1 is discharged is large. It determines with the short circuit abnormality of the system battery 1 having generate | occur | produced.

  In step S22, the ECU 4 that has determined that the short circuit abnormality of the low voltage battery 1 has not occurred is restored to the optimum voltage Vo2 that can recover the discharge for the determination of the short circuit abnormality of the low voltage battery 1. Set the output voltage. The optimum voltage Vo2 is determined according to a map of the temperature of the low-voltage battery 1 and the battery voltage, for example, based on a detection signal from the sensor 7. The DC-DC converter 3 starts supplementary charging of the low-voltage battery 1 by outputting an output current with an output voltage Vo2 (for example, 13.5-14.5 V) adjusted according to a command signal from the ECU 4. Thereby, the part discharged for the determination of the short circuit abnormality of the low voltage battery 1 can be compensated.

  As shown in step S24, the DC-DC converter 3 continues charging at the output voltage Vo2 until a predetermined time T3 (for example, 1 minute) elapses from the start of output at the output voltage Vo2. The time T3 may be changed according to the time when the output of the DC-DC converter 3 is stopped, and may be set to a time necessary to compensate for the discharge for the determination of the short circuit abnormality of the low voltage battery 1.

  In step S <b> 26, the ECU 4 sets the output voltage of the DC-DC converter 3 to the optimum voltage Vo <b> 3 that does not discharge the low voltage battery 1. The optimum voltage Vo3 is determined according to a map of the temperature of the low-voltage battery 1 and the battery voltage, for example, based on a detection signal from the sensor 7. The DC-DC converter 3 outputs an output current (that is, a charging current flowing into the low-voltage battery 1 becomes zero) at an output voltage Vo3 (for example, 12.5 to 13.5 V) adjusted according to a command signal from the ECU 4. Current). Thereby, the overcharge and overdischarge of the low-voltage battery 1 can be prevented.

  As shown in step S28, the DC-DC converter 3 outputs an output current at the output voltage Vo3 until a predetermined time T4 (for example, 30 minutes) elapses from the start of output at the output voltage Vo3. Since the output of the DC-DC converter 3 stops again after the elapse of time T4 (step S16), the interval of the determination timing of the short circuit abnormality of the low-voltage battery 1 can be adjusted by changing the length of the time T4. . If the charging / discharging cycle of the low-voltage battery 1 is made too short, the life of the low-voltage battery 1 is affected. Therefore, the time T4 may be set to a relatively long time.

  On the other hand, in step S30, the ECU 4 having determined that the short circuit abnormality of the low voltage battery 1 has occurred, the DC voltage is set to the optimum voltage Vo4 so that the low voltage battery 1 is not charged and other electronic devices are not reset. -The output voltage of the DC converter 3 is set. The DC-DC converter 3 outputs an output current with an output voltage Vo4 (for example, 11.5 V) adjusted according to a command signal from the ECU 4. Thereby, it can prevent that the low voltage | pressure system battery 1 in which the short circuit abnormality has generate | occur | produced is charged, preventing reset generate | occur | producing in another electronic device.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the low voltage system battery 1 is shown as the first battery of the first voltage system, and the high voltage system battery 2 is used as the second voltage system battery having a higher voltage than the first voltage system. Indicated. However, the first battery may be at a higher voltage or the same voltage as the second battery.

  Further, the batteries 1 and 2 may be secondary batteries. Therefore, for example, the battery 1 may be a lithium ion battery or a nickel metal hydride battery.

  Further, the DC-DC converter 3 and the ECU 4 may be realized as an integrated device, not as separate bodies.

DESCRIPTION OF SYMBOLS 1 Low voltage system battery 2 High voltage system battery 3 DC-DC converter 4 ECU
DESCRIPTION OF SYMBOLS 5 Charge control part 6 Relay 7 Sensor 8 High voltage system power supply path 9 Low voltage system power supply path 10 Vehicle power supply system 11 Power receiving side connector 16 Load 21 Power supply side connector 22 Power supply line 23 Plug 24 Charging cable 25 External power supply

Claims (13)

An in-vehicle first battery;
An in-vehicle second battery;
An output means for outputting a charging current of the first battery by converting the supply power of the second battery and / or an external power source capable of charging the second battery, into a voltage ;
By stopping the output of the output means for a predetermined time during charging of the second battery by the external power source while the external power source is connected to the vehicle, the first battery is discharged. A power supply system comprising: determination means for determining a short circuit abnormality of one battery.   The power supply system according to claim 1, wherein the output of the output unit is intermittently stopped for a predetermined time.   3. The power supply system according to claim 1, wherein when it is determined that there is no short circuit abnormality of the first battery, the first battery is supplementarily charged by an output of the output unit.   The power supply system according to claim 3, wherein the output unit supplementarily charges the first battery based on a detection voltage of the first battery.   The power supply system according to claim 3 or 4, wherein the output unit supplementarily charges the first battery based on a detected temperature of the first battery.   6. The power supply system according to claim 3, wherein a time for supplementarily charging the first battery is changed according to a time when the output of the output voltage is stopped.   The power supply system according to any one of claims 3 to 6, wherein an output voltage of the output means is set so that the first battery is not discharged after supplementary charging of the first battery.   The power supply system according to claim 7, wherein an output voltage of the output means is set according to a detection voltage of the first battery so that the first battery is not discharged.   The power supply system according to claim 7 or 8, wherein an output voltage of the output means is set according to a detected temperature of the first battery so that the first battery is not discharged.   10. The output voltage of the output means is set so as not to cause a reset of a predetermined electronic device when it is determined that there is a short circuit abnormality in the first battery. Power system.   11. The output voltage of the output unit is set so as to prevent the first battery from being charged when it is determined that there is a short circuit abnormality in the first battery. Power system.   The power supply system according to any one of claims 1 to 11, wherein the output means is a DC-DC converter. The output of the output means for outputting the charging current of the in-vehicle first battery by converting the voltage supplied to the in-vehicle second battery and / or the power supplied from the vehicle external power source capable of charging the second battery, While the power source is connected to the vehicle, the first battery is discharged for a predetermined time while the second battery is being charged by the external power source, and the first battery is discharged to determine a short circuit abnormality of the first battery. A battery abnormality determination method.

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