JP2015077036A - Electrical power system of vehicle and power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrical power system of a vehicle which can charge an auxiliary machine battery without applying a high voltage onto equipment other than a DCDC converter, and a power supply unit.SOLUTION: An electrical power system of a vehicle includes: a high voltage main machine battery 11 for supplying electric power to an MG 60; an auxiliary machine battery 12 which has a voltage lower than the main machine battery 11, and supplies electric power to a vehicle auxiliary machine 80; a DCDC converter 13 which is connected between the main machine battery 11 and the auxiliary machine battery 12, and converts a voltage value of an inputted DC voltage into a different voltage value and outputs; SMRs 14a, 14b which are connected to the main machine battery 11, and open and close a connection between the main machine battery 11 and equipment other than the DCDC converter 13; and a BMU 30 which controls the DCDC converter 13 and the SMRs 14a, 14b.

Description

  The present invention relates to a power supply system for a vehicle including a high-voltage main battery and a low-voltage auxiliary battery, and a power supply unit.

  A hybrid vehicle includes a high-voltage main unit battery that supplies electric power to a traveling motor and an auxiliary battery that is lower in voltage than the main unit battery, and controls an auxiliary unit other than the traveling motor from the auxiliary battery, for example, a vehicle. Electric power is supplied to the ECU and electrical components. Therefore, even if the amount of power stored in the main battery is sufficient, if the amount of power stored in the auxiliary battery decreases and power cannot be supplied to the auxiliary device, the vehicle ECU or the like cannot be started and the vehicle cannot be started. .

  Therefore, in Patent Document 1, when a certain time has elapsed after the ignition switch of the vehicle is turned off, the high voltage relay is turned on by a timer to connect the main battery to the power supply wiring and to operate the DCDC converter. . And electric power is supplied to an auxiliary machine battery from a main machine battery via a DCDC converter, and the auxiliary machine battery is prevented from rising.

JP 2006-174619 A

  In Patent Document 1, when the ignition switch of the vehicle is in an off state, the high voltage relay is turned on by the timer, and a high voltage is applied to the inverter and the motor connected to the power supply wiring. Therefore, it is necessary to pay attention to contact with the inverter and the motor when the vehicle is maintained while the vehicle is stopped.

  In view of the above circumstances, it is a main object of the present invention to provide a vehicle power supply system and a power supply unit that can charge an auxiliary battery without applying a high voltage to a device other than a DCDC converter.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a power supply system for a vehicle, and a high-voltage main unit battery that supplies electric power to a vehicle driving motor, and a lower voltage than the main unit battery, An auxiliary battery that supplies electric power to the auxiliary machine of the vehicle, and a DCDC converter that is connected between the main battery and the auxiliary battery and converts the voltage value of the input DC voltage to a different voltage value and outputs the voltage value And an open / close device connected to the main unit battery for opening / closing a connection between the main unit battery and a device other than the DCDC converter, and a battery control device for controlling the DCDC converter and the open / close device.

  According to the first aspect of the present invention, the DCDC converter is connected between the main battery and the auxiliary battery. Further, when the battery control device opens the switchgear connected to the main battery, only the DCDC converter is connected to the main battery, and devices other than the DCDC converter are not connected. For this reason, it is possible to form a power supply path that connects the main battery, the DCDC converter, and the auxiliary battery even when the switchgear is kept open. Therefore, the auxiliary battery can be charged without applying a high voltage to equipment other than the DCDC converter by controlling the DCDC converter with the switchgear opened by the battery control device.

  The invention according to claim 6 is a power supply unit, which is a main battery that supplies high-voltage power, an auxiliary battery that supplies lower-voltage power than the main battery, the main battery, and the auxiliary battery. And a DCDC converter that converts a voltage value of an input DC voltage into a different voltage value and outputs the same, and a switching device that is connected to the main battery and disconnects the main battery from devices other than the DCDC converter And a battery control device for controlling the DCDC converter and the switchgear.

  According to the sixth aspect of the present invention, similarly to the first aspect, it is possible to form a power supply path for connecting the main battery, the DCDC converter, and the auxiliary battery even when the switchgear is kept open. Therefore, the battery controller can charge the auxiliary battery without applying a high voltage to equipment other than the DCDC converter by controlling the DCDC converter with the switchgear opened. Further, power management can be performed only by a battery control device independent of other control devices.

The figure which shows the structure of the power supply system of a hybrid vehicle. The flowchart which shows the process sequence which charges an auxiliary machine battery.

  Hereinafter, an embodiment in which a vehicle power supply system is applied to a hybrid vehicle will be described with reference to the drawings.

  As shown in FIG. 1, a hybrid vehicle to which the vehicle power supply system according to this embodiment is applied includes an engine 50, an MG 60 (travel motor), an inverter 70, a vehicle auxiliary device 80, an HCU 40, and a power supply unit 10. The power supply unit 10 corresponds to the vehicle power supply system according to the present embodiment.

  The engine 50 is an internal combustion engine that generates driving power for the vehicle. The MG 60 operates as a motor that generates traveling power of the vehicle and also operates as a generator that supplies power to the main battery 11 included in the power supply unit 10. When MG 60 operates as a motor, MG 60 receives supply of high voltage (for example, about 300 V) from main unit battery 11 via inverter 70.

  The inverter 70 converts the DC power of the main battery 11 into AC power based on a command from the HCU 40 and supplies the AC power to the MG 60 to operate the MG 60 as a motor. The inverter 70 operates the MG 60 as a generator based on a command from the HCU 40, converts the AC power generated by the MG 60 into DC power, supplies the DC power to the main battery 11, and charges the main battery 11.

  The vehicle auxiliary device 80 is an in-vehicle electrical component other than the MG 60, and is, for example, an electronic control device including an HCU 40 and a BMU 30 described later, various actuators, or the like. The vehicle auxiliary machine 80 operates by receiving power from the auxiliary battery 12 included in the power supply unit 10.

  The HCU 40 (Hybrid Control Unit) includes a microcomputer 41, a communication circuit 42, and an input / output circuit 43, and controls the engine 50 and the inverter 70. The communication circuit 42 can communicate with the communication circuit 32 included in the power supply unit 10, and receives information such as the charging state of the main battery 11 from the communication circuit 32.

  The ST signal is input to the input / output circuit 43 from the STSW 18 (start switch) included in the power supply unit 10. Although not shown, the input / output circuit 43 includes vehicles such as an accelerator opening sensor that detects the opening of the accelerator pedal, a brake sensor that detects the amount of operation of the brake pedal of the vehicle, and a vehicle speed sensor that detects the vehicle speed. Signals from various sensors that detect the operating state are input.

  The microcomputer 41 is activated by receiving the supply of the main power supply voltage Vm from the power supply circuit 35 described later as the STSW 18 is turned on by the user and the ST signal input to the input / output circuit 43 changes from the low level to the high level. To do. Then, the microcomputer 41 controls the inverter 70 and the engine 50 based on the state of charge of the main battery 11, the vehicle running load detected from the accelerator opening sensor and the vehicle speed sensor, and the like.

  For example, when the stored amount of the main battery 11 is larger than a predetermined amount and the traveling load is small, the MG 60 is operated as a motor and the vehicle is driven by the output of the MG 60. Further, when the stored amount of the main battery 11 is larger than a predetermined amount and the traveling load is large, the traveling power that is insufficient with the output of the MG 60 is compensated with the output of the engine 50. When the stored amount of main battery 11 is smaller than a predetermined amount, the vehicle is driven by the output of engine 50 and MG 60 is operated as a generator by the output of engine 50 to charge main battery 11.

  Next, the configuration of the power supply unit 10 will be described. The power supply unit 10 includes a main battery 11 (main battery), an auxiliary battery 12 (auxiliary battery), a DCDC converter 13, SMRs 14a and 14b (switching devices), a relay 19, an STSW 18, a voltage sensor 15, and a voltage sensor 15a (voltage detection means). ), Current sensor 16, voltage sensor 17, BMU 30 (battery control device), and housing 20. Main battery 11, auxiliary battery 12, DCDC converter 13, SMR 14 a, b, relay 19, STSW 18, voltage sensor 15, voltage sensor 15 a, current sensor 16, voltage sensor 17, and BMU 30 are housed in an insulator housing 20. Has been.

  The main battery 11 is composed of a plurality of battery cells 11a to 11n connected in series with each other, and is a high-voltage (for example, about 300V) storage battery that supplies power to the MG 60 and the auxiliary battery 12. As the main battery 11, for example, a lithium ion storage battery is employed. In addition, each battery cell 11a-11n is provided with the equalization circuit which is not shown in figure, respectively.

  The auxiliary battery 12 is a storage battery having a lower voltage (for example, 12V) than the main battery 11. The auxiliary battery 12 is directly connected to the vehicle auxiliary machine 80 and the power supply circuit 35 included in the BMU 30, and constantly supplies power to the vehicle auxiliary machine 80 and the power supply circuit 35. For example, a lead storage battery is employed as the auxiliary battery 12.

  The DCDC converter 13 is connected between the main battery 11 and the auxiliary battery 12. Specifically, the DCDC converter 13 and the main battery 11 are directly connected, and the DCDC converter 13 and the auxiliary battery 12 are connected via a relay 19. The DCDC converter 13 steps down the input high-voltage DC voltage of the main battery 11 to convert it to a low-voltage DC voltage, and outputs it to the auxiliary battery 12.

  The SMRs 14a and 14b (System Main Relay) are switches that open and close the connection between the high-voltage main unit battery 11 and the high-voltage system including the inverter 70 and the MG 60. That is, the SMRs 14 a and 14 b are switches that are connected to the main battery 11 and open and close the connection between the main battery 11 and devices other than the DCDC converter 13. The relay 19 is a switch that opens and closes the connection between the DCDC converter 13 and the auxiliary battery 12.

  The SMRs 14a and 14b and the relay 19 are opened and closed based on a signal from the BMU 30. Specifically, when the SMR signal input from the BMU 30 to the SMRs 14a and 14b changes from the low level to the high level, the SMRs 14a and 14b are closed and the main battery 11 and the inverter 70 are connected. As a result, MG 60 can be operated as a motor and main battery 11 can be charged. On the other hand, when the signal input from the BMU 30 to the SMRs 14a and 14b changes from the high level to the low level, the SMRs 14a and 14b are opened, and the connection between the main battery 11 and the high voltage system is cut off.

  Further, when the DCDC operation signal input from the BMU 30 to the relay 19 changes from the low level to the high level, the relay 19 is closed and the DCDC converter 13 and the auxiliary battery 12 are connected. In other words, a power supply path for connecting the main battery 11, the DCDC converter 13, and the auxiliary battery 12 is formed. As a result, the DCDC converter 13 is driven, and power is supplied from the main battery 11 to the auxiliary battery 12 via the DCDC converter 13 to charge the auxiliary battery 12. On the other hand, when the DCDC operation signal input from the BMU 30 to the relay 19 changes from the high level to the low level, the relay 19 is opened, the DCDC converter 13 and the auxiliary battery 12 are cut off, and the DCDC converter 13 is driven. Stop.

  In the power supply unit 10, the DCDC converter 13 is installed not on the high-voltage system side but on the main battery 11 side with respect to the SMRs 14a and 14b. Therefore, when the relay 19 is closed while the SMRs 14a and 14b are maintained in the open state, the auxiliary battery 12 can be charged with the devices other than the DCDC converter 13 disconnected from the main battery 11.

  The voltage sensor 15 detects the voltage Vmain of the main battery 11 and outputs the detected voltage Vmain to the BMU 30. Although simplified in the figure, n voltage sensors 15a are connected in parallel to each of the battery cells 11a to n included in the main battery 11, and detect the voltage Vc of each battery cell 11a to n. The detected voltage Vc of each battery cell 11a to n is output to the BMU 30.

  Current sensor 16 detects charge / discharge current Imain flowing between main unit battery 11 and inverter 70 and outputs the detected charge / discharge current Imain to BMU 30. Since the battery cells 11a to 11n included in the main battery 11 are connected in series with each other, the charge / discharge current Imain flowing through the battery cells 11a to 11n is equal. Voltage sensor 17 detects voltage Vsub of auxiliary battery 12 and outputs the detected voltage Vsub to BMU 30.

  The STSW 18 is closed when the user turns on the start switch of the vehicle, and outputs a high-level ST signal to the BMU 30 and the HCU 40. The STSW 18 is opened when the user turns off the start switch of the vehicle, and outputs a low-level ST signal to the BMU 30 and the HCU 40.

  The BMU 30 (Battery Management Unit) includes a microcomputer 31, a communication circuit 32, an input / output circuit 33, a timer IC 34, and a power supply circuit 35. The communication circuit 32 can communicate with the communication circuit 42 included in the HCU 40, and receives vehicle information such as the operation state of the MG 60 from the communication circuit 42.

  The input / output circuit 33 receives the ST signal from the STSW 18 and detects the voltage Vmain, the voltage Vc, the current Imain, and the voltage Vsub detected from the voltage sensor 15, the voltage sensor 15 a, the current sensor 16, and the voltage sensor 17. Are entered respectively. The SMR signal and the DCDC operation signal are output from the input / output circuit 33 to the SMRs 14a and 14b and the relay 19, respectively.

  The power supply circuit 35 generates a main power supply voltage Vm and a sub power supply voltage Vs from the voltage of the auxiliary battery 12 that is always supplied. The power supply circuit 35 supplies the main power supply voltage Vm to the microcomputer 31 of the BMU 30 and the microcomputer 41 of the HCU 40 and supplies the sub power supply voltage Vs to the timer IC 34 of the BMU 30.

  The timer IC 34 operates in response to the supply of the sub power supply voltage Vs from the power supply circuit 35. The timer IC 34 receives the ST signal from the microcomputer 31 and the timer time W1 is set by the microcomputer 31. The timer IC 34 counts the switch-off timer during a period from the reception of the low level ST signal from the microcomputer 31 to the reception of the high level ST signal, that is, the period when the STSW 18 is in the off state. The timer IC 34 outputs a high-level power activation signal to the microcomputer 31 when the counted switch-off timer exceeds the set timer time W1. When receiving a clear command from the microcomputer 31, the timer IC 34 resets the output level of the power activation signal to low level and resets the count of the switch-off timer to zero.

  When the microcomputer 31 receives a high-level ST signal from the STSW 18 and receives a high-level power activation signal from the timer IC 34, the microcomputer 31 is activated by receiving the supply of the main power voltage Vm from the power circuit 35.

  When the microcomputer 31 is activated when the STSW 18 is turned on, the microcomputer 31 outputs a high level ST signal to the timer IC 34 and also outputs a high level SMR signal to the SMRs 14a and 14b, thereby closing the SMRs 14a and 14b. To do.

  Further, the microcomputer 31 determines that the operation stop condition is satisfied when all necessary processes are completed after receiving the low-level ST signal from the STSW 18. When it is determined that the operation stop condition is satisfied, the microcomputer 31 sets the timer time W1 of the timer IC 34 and outputs a clear command and a low-level ST signal to the timer IC 34. Further, the microcomputer 31 outputs a low-level SMR signal to the SMRs 14a and 14b, thereby opening the SMRs 14a and 14b. Then, the microcomputer 31 stops supply of the main power supply voltage Vm from the power supply circuit 35 and stops its own operation.

  Further, when the microcomputer 31 is activated by receiving a high-level power activation signal from the timer IC 34 while the STSW 18 is in an off state, the microcomputer 31 has completed processing to be performed while the vehicle is stopped. It is determined that the operation stop condition is satisfied. When it is determined that the operation stop condition is satisfied, the microcomputer 31 sets the timer time W1 of the timer IC 34 and outputs a clear command to the timer IC 34. Then, the microcomputer 31 stops supply of the main power supply voltage Vm from the power supply circuit 35 and stops its own operation. Therefore, during the period in which the STSW 18 is in the OFF state, the microcomputer 31 is periodically activated at approximately the timer time W1 interval. Note that the SMRs 14a and 14b are maintained in the open state while the STSW 18 is in the off state.

  Further, the microcomputer 31 operates the equalization circuit provided in the plurality of battery cells 11a to 11n included in the main battery 11 periodically at intervals of the timer time W1 during the period when the vehicle start switch is in the OFF state. The equalization process of the storage amount of the battery cells 11a to 11n is performed. Further, the microcomputer 31 charges the auxiliary battery 12 at a timing at which the equalization processing of the plurality of battery cells 11a to 11n is performed. When the microcomputer 31 charges the auxiliary battery 12, the internal resistance of each battery cell 11a-n is estimated based on the amount of voltage drop of each battery cell 11a-n detected by the voltage sensor 15a. And the microcomputer 31 determines the deterioration degree of each battery cell 11a-n based on the estimated internal resistance of each battery cell 11a-n. Specifically, the microcomputer 31 determines that the degree of deterioration of the battery cells 11a to 11n is larger as the estimated internal resistance of the battery cells 11a to 11n is larger.

  Next, a processing procedure for charging the auxiliary battery 12 will be described with reference to the flowchart of FIG. This processing procedure is repeatedly executed by the timer IC 34 and the microcomputer 31 of the BMU 30.

  First, in S11, it is determined whether or not the STSW 18 is on. Specifically, if the timer IC 34 has not received a low-level ST signal after receiving a high-level ST signal from the microcomputer 31, the timer IC 34 determines that the STSW 18 is in an on state (YES). On the other hand, if the timer IC 34 does not receive the high-level ST signal after receiving the low-level ST signal from the microcomputer 31, the timer IC 34 determines that the STSW 18 is in the off state (NO). When the microcomputer 31 is activated, when the microcomputer 31 is receiving a high-level ST signal, the microcomputer 31 determines that the STSW 18 is on, and the microcomputer 31 receives a low-level ST signal. The microcomputer 31 may determine that the STSW 18 is off.

  If it is determined in S11 that the STSW 18 is in an on state (YES), in S12, the microcomputer 31 executes a normal process when the STSW 18 is on. Specifically, the microcomputer 31 maintains the SMRs 14a and 14b in a closed state so that power can be transferred between the main battery 11 and the MG 60 via the inverter 70. Thereafter, this process is terminated.

  On the other hand, if it is determined in S11 that the STSW 18 is off (NO), the timer IC 34 increments the count of the switch-off timer by 1 in S13. At this time, the SMRs 14a and 14b are maintained in the open state. Subsequently, in S14, the timer IC 34 determines whether or not the switch-off timer is equal to or longer than a timer time W1 (for example, 1 hour) set by the microcomputer 31. That is, the timer IC 34 determines whether or not the elapsed time since the previous shutdown of the microcomputer 31 has become W1 or more. If the elapsed time is less than W1 (NO), this process ends. On the other hand, if the elapsed time is greater than or equal to W1 (YES), the process proceeds to S15.

  In S <b> 15, the timer IC 34 transmits a high level power activation signal to the microcomputer 31 to activate the microcomputer 31.

  Subsequently, in S16, the microcomputer 31 determines whether or not the difference between the voltages of the battery cells 11a to 11n is equal to or higher than the voltage W2 based on the voltage Vc of the battery cells 11a to 11n detected by the voltage sensor 15a. That is, the microcomputer 31 determines whether or not the difference between the maximum voltage and the minimum voltage among the voltages of the battery cells 11a to 11n is equal to or higher than the voltage W2. Here, the voltage W2 is a value at which it can be determined that the variation among the battery cells 11a to 11n is sufficiently small.

  In S16, when the voltage difference between the battery cells 11a to 11n is equal to or higher than the voltage W2 (YES), the voltage of each battery cell 11a to 11n, that is, the variation in the charged amount is large. The equalization process of 11a-n is performed. The microcomputer 31 repeatedly executes the processes of S16 and S17 until the voltage difference between the battery cells 11a to 11n is less than the voltage W2.

  On the other hand, in S16, when the voltage difference between the battery cells 11a to 11n is less than the voltage W2 (NO), since the variation in the voltage of each battery cell 11a to 11n is sufficiently small, the microcomputer 31 is connected to the battery cells 11a to 11a. The process proceeds to S18 without performing the equalization process of n.

  In S18, the microcomputer 31 determines whether or not the storage amount of the auxiliary battery 12 is smaller than the storage amount W3 (predetermined amount). Here, the charged amount W3 is a value at which it can be determined that the auxiliary battery 12 needs to be charged.

  There is a correlation between the charged amount of the auxiliary battery 12 and the voltage Vsub of the auxiliary battery 12. Therefore, when the voltage of the auxiliary battery 12 when the charged amount of the auxiliary battery 12 is the charged amount W3 is V3, the microcomputer 31 determines whether or not the voltage Vsub detected by the voltage sensor 17 is smaller than the voltage V3. judge. When the voltage Vsub is equal to or higher than the voltage V3, that is, when the charged amount of the auxiliary battery 12 is equal to or higher than the charged amount W3 (NO), it is not necessary to charge the auxiliary battery 12, and the process proceeds to S22. In S22, the microcomputer 31 determines that the operation stop condition is satisfied, sets the timer time W1 of the timer IC 34, outputs a clear command to the timer IC 34, and shuts down. Then, the microcomputer 31 stands by until the next high level ST signal or high level power activation signal is received.

  On the other hand, when the voltage Vsub is less than the voltage V3, that is, when the charged amount of the auxiliary battery 12 is smaller than the charged amount W3 (YES), the process proceeds to S19.

  In S <b> 19, the microcomputer 31 determines whether or not the charged amount of the main battery 11 is equal to or greater than the charged amount W <b> 4. Here, the charged amount W4 is a value that can be determined that even if power is supplied from the main battery 11 to the auxiliary battery 12, the charged amount that can crank the engine remains in the main battery 11.

  Specifically, in order to prevent overdischarge of the battery cells 11a to 11n included in the main battery 11, it is determined whether or not the minimum value of the voltage Vc of the battery cells 11a to 11n is equal to or higher than the voltage V4. When the voltage Vc of each of the battery cells 11a to 11n is the voltage V4, the charged amount of the main battery 11 is W4. If the minimum value of the voltage Vc of the battery cells 11a to 11n is smaller than the voltage V4 (NO), the auxiliary battery 12 is not charged and the process proceeds to S22. In S22, the microcomputer 31 determines that the operation stop condition is satisfied, sets the timer time W1 of the timer IC 34, outputs a clear command to the timer IC 34, and shuts down. Then, the microcomputer 31 stands by until the next high level ST signal or high level power activation signal is received.

  On the other hand, when the minimum value of the voltage Vc of the battery cells 11a to 11n is equal to or higher than the voltage V4, that is, when the voltage Vc of the battery cells 11a to 11n is equal to or higher than the voltage V4 (YES), the process proceeds to S20.

  In S <b> 20, the microcomputer 31 transmits a high-level DCDC operation signal to the relay 19, closes the relay 19, and activates the DCDC converter 13. As a result, a power supply path that connects the main battery 11, the DCDC converter 13, and the auxiliary battery 12 is formed.

  Subsequently, in S <b> 21, the microcomputer 31 drives the DCDC converter 13 to supply power from the main battery 11 to the auxiliary battery 12 to charge the auxiliary battery 12.

  When power is supplied from the main battery 11 to the auxiliary battery 12, the main battery 11 is discharged at a constant low rate current. Therefore, the internal resistances of the battery cells 11a to 11n can be accurately estimated from the voltage drop amounts of the battery cells 11a to 11n included in the main battery 11. Therefore, when charging the auxiliary battery 12, the microcomputer 31 estimates the internal resistance of each battery cell 11a-n based on the amount of voltage drop of each battery cell 11a-n detected by the voltage sensor 15a. The deterioration degree of each battery cell 11a-n is determined.

  The microcomputer 31 repeatedly executes the processes of S18 to S19 until the storage amount of the auxiliary battery 12 is equal to or greater than the storage amount W3 or until the storage amount of the main battery 11 is less than the storage amount W4. When the stored amount of auxiliary battery 12 is equal to or greater than stored amount W3, or when the stored amount of main battery 11 is less than stored amount W4, the process proceeds to S22. In S22, the microcomputer 31 determines that the operation stop condition is satisfied, sets the timer time W1 of the timer IC 34, outputs a clear command to the timer IC 34, and shuts down. Then, the microcomputer 31 stands by until the next high level ST signal or high level power activation signal is received. This process is complete | finished above.

  According to this embodiment described above, the following effects are obtained.

  When the SMRs 14 a and 14 b connected to the main unit battery 11 are opened by the BMU 30, only the DCDC converter 13 is connected to the main unit battery 11, and devices other than the DCDC converter 13 are not connected. Therefore, even when the SMRs 14a and 14b are left open, a power supply path that connects the main battery 11, the DCDC converter 13, and the auxiliary battery 12 can be formed. Therefore, the BMU 30 charges the auxiliary battery 12 without applying high voltage to devices other than the DCDC converter 13 by driving the DCDC converter 13 with the relay 19 closed while the SMRs 14a and 14b are opened. It can be performed.

  While the vehicle is stopped, the SMRs 14a and 14b are kept open, that is, with only the DCDC converter 13 connected to the main battery 11, the voltage of the main battery 11 is stepped down by the DCDC converter 13 and the auxiliary machine Power is supplied to the battery 12, and the auxiliary battery 12 is charged. Therefore, it is possible to prevent a high voltage from being applied to devices other than the DCDC converter 13 such as the MG 60 and the inverter 70 while the vehicle is stopped.

  Since the auxiliary battery 12 can be charged only by the BMU 30 while the vehicle is stopped, it is not necessary to activate the HCU 40 that controls other devices of the vehicle. Therefore, compared to the case where both the HCU 40 and the BMU 30 need to be activated, the dark current while the vehicle is stopped can be suppressed.

  When the vehicle is stopped, the auxiliary battery 12 is charged by the microcomputer 31 of the BMU 30 at the timing when the microcomputer 31 of the BMU 30 equalizes the plurality of battery cells 11a to 11n included in the main battery 11. Therefore, it is possible to suppress the number of times that the microcomputer 31 of the BMU 30 is activated while the vehicle is stopped.

  When supplying power from the main battery 11 to the auxiliary battery 12 while the vehicle is stopped, the internal resistance of each battery cell 11a-n is determined from the amount of voltage drop of each battery cell 11a-n constituting the main battery 11. It can be estimated accurately. Furthermore, the deterioration degree of each battery cell 11a-n can be determined based on the internal resistance of each battery cell 11a-n estimated accurately.

  Only when the auxiliary battery 12 needs to be charged, the auxiliary battery 12 is charged. Therefore, it is possible to prevent the amount of power stored in main battery 11 from being unnecessarily reduced.

  -Power management can be performed only by the BMU 30 independent of other control devices.

  Since the devices constituting the power supply unit 10 are accommodated in the housing 20, the power supply unit 10 can be easily handled and the safety against high voltage can be improved.

(Other embodiments)
The microcomputer 31 may charge the auxiliary battery 12 at a timing different from the timing at which the equalization processing of the battery cells 11a to n included in the main battery 11 is performed while the vehicle is stopped. In this case, the microcomputer 31 is activated by the timer IC 34 at a timing different from the timing at which the equalization process is performed while the vehicle is stopped.

  The microcomputer 31 may not perform the equalization process of the battery cells 11a to 11n included in the main battery 11 while the vehicle is stopped. In this case, the microcomputer 31 is periodically activated by the timer IC 34 while the vehicle is stopped, and the auxiliary battery 12 is charged by the microcomputer 31.

  The DCDC converter 13 may be a bidirectional type. When the DCDC converter 13 is a bidirectional type, the low-voltage DC voltage of the auxiliary battery 12 can be boosted and converted to a high-voltage DC voltage and supplied to the main battery 11.

  The SMRs 14a and 14b may be any switches that can connect and disconnect the main battery 11 and the high voltage system. Further, the number of switches is not limited to two. For example, a precharge switch may be provided in parallel with the SMR 14a.

  The relay 19 may be any switch that can connect and disconnect the DCDC converter 13 and the auxiliary battery 12.

  -The apparatus which comprises the power supply unit 10 does not necessarily need to be accommodated in the one housing 20. FIG.

  The other control device must be activated while the vehicle is stopped, but the battery control device may be composed of the BMU 30 and another control device such as the HCU 40. That is, you may make it control the DCDC converter 13 and SMR14a, b by BMU30 and another control apparatus. Even in this case, the auxiliary battery 12 can be charged without applying a high voltage to equipment other than the DCDC converter.

  The power supply unit 10 may be mounted on a train other than a vehicle, a ship, a device powered by electric power, or the like.

  DESCRIPTION OF SYMBOLS 10 ... Power unit, 11 ... Main machine battery, 12 ... Auxiliary battery, 13 ... DCDC converter, 30 ... BMU, 60 ... MG, 14a, b ... SMR.

Claims (8)

A high-voltage main battery (11) for supplying electric power to the vehicle motor (60);
An auxiliary battery (12) that is lower in pressure than the main battery and supplies electric power to the auxiliary equipment of the vehicle;
A DCDC converter (13) connected between the main unit battery and the auxiliary unit battery, which converts a voltage value of an input DC voltage into a different voltage value and outputs the voltage value;
An open / close device (14a, b) connected to the main unit battery for opening and closing a connection between the main unit battery and a device other than the DCDC converter;
A vehicle power supply system comprising: a battery control device (30) for controlling the DCDC converter and the switchgear.   The battery control device drives the DCDC converter while maintaining the opening / closing device in an open state during a period when the start switch of the vehicle is in an off state, and the auxiliary battery from the main unit battery via the DCDC converter. The vehicle power supply system according to claim 1, wherein the auxiliary battery is charged by supplying power to the vehicle.   3. The vehicle power supply system according to claim 2, wherein the battery control device charges the auxiliary battery at a timing at which the plurality of battery cells (11 a to 11 n) included in the main battery are equalized. 4. The main battery is composed of a plurality of battery cells connected in series with each other,
Voltage detecting means (15a) for detecting the voltage of each battery cell of the main battery,
The battery control device estimates the internal resistance of each battery cell based on the amount of voltage drop of each battery cell detected by the voltage detection means when charging the auxiliary battery, and each estimated The power supply system for a vehicle according to claim 2 or 3, wherein the degree of deterioration of each battery cell is determined based on the internal resistance of the battery cell.   The vehicle power supply system according to any one of claims 2 to 4, wherein the battery control device charges the auxiliary battery on the condition that a storage amount of the auxiliary battery is smaller than a predetermined amount. A main battery (11) for supplying high-voltage power;
An auxiliary battery (12) for supplying power lower than that of the main battery;
A DCDC converter (13) connected between the main battery and the auxiliary battery, which converts the voltage value of the input DC voltage into a different voltage value and outputs it;
An opening / closing device (14a, b) connected to the main battery and opening / closing a connection between the main battery and a device other than the DCDC converter;
And a battery control device (30) for controlling the DCDC converter and the switchgear. The power supply unit includes a housing (20),
The power supply unit according to claim 6, wherein the main battery, the auxiliary battery, the DCDC converter, the switching device, and the battery control device are accommodated in the housing. The power supply unit is mounted on a vehicle,
The battery control device drives the DCDC converter while maintaining the opening / closing device in an open state during a period in which the start switch of the vehicle is in an off state, and transfers the main battery from the main battery to the auxiliary battery via the DCDC converter. The power supply unit according to claim 6 or 7, wherein the auxiliary battery is charged by supplying power.

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