JP5609401B2 - Vehicle power supply apparatus and power supply control method - Google Patents

Description

  The present invention relates to a power supply device mounted on a vehicle and a power supply control method.

  An electric vehicle that drives a vehicle with an electric motor and a hybrid vehicle that uses a gasoline engine and an electric motor together include a high voltage battery and a low voltage battery. The high-voltage battery is a lithium battery that supplies power to an electric motor or the like. The low-voltage battery is a battery that supplies power to an auxiliary device such as an electronic control unit, a wiper, or a headlight that controls driving of an electric motor or an engine. The low-voltage battery is connected to the output of a DC / DC converter provided at the subsequent stage of the high-voltage battery, and charges the electric power output from the DC / DC converter.

  However, there is a conventional power supply switch between the high voltage battery and the DC / DC converter, and the power supply switch is controlled by an electronic control unit including a computer connected to the low voltage battery. For this reason, when the low voltage battery is not sufficiently charged to operate the electronic control unit, the power supply switch cannot be controlled, and in the worst case, the vehicle cannot be started.

  For example, a power supply control device for a vehicle that can perform charging control of a low-voltage battery with an ignition switch in an off state while ensuring safety is known. According to this power supply control device, the power supply control unit that operates the charging circuit connected to the high voltage battery and charges the low voltage battery based on the state of charge of the low voltage battery operates intermittently when the ignition switch circuit is turned off. . Then, when it is determined that charging is necessary, that is, when the charging environment such as the hood is closed, charging control for operating the charging circuit is executed.

JP 2007-189760 A

  The present invention has been made in view of the above circumstances, and provides a power supply device for a vehicle and a power supply control method for preventing insufficient charging of a low-voltage battery connected to a subsequent stage of a DC / DC converter. Objective.

  A power supply device for a vehicle that is one of the embodiments includes a first battery, a DC / DC converter, a second battery, and a control unit. A high voltage is supplied to the first battery high voltage system via a power supply switch. The DC / DC converter is directly connected to the first battery, and power is supplied from the first battery. The second battery is supplied with power from the DC / DC converter and supplies a low voltage to the low voltage system via an ignition switch. The control unit is directly connected to the second battery, controls the start and stop of the DC / DC converter, and charges the second battery so that the power supply switch can be switched.

  Further, when the control unit detects that the ignition switch is not supplying power to the low-voltage system, the control unit can control the start and stop of the DC / DC converter to switch the power supply switch. Charge the second battery to state.

A power supply device for a vehicle that is another aspect of the implementation includes a first battery, a DC / DC converter, a second battery, and an electronic control unit.
The first battery supplies a high voltage to the high voltage system via a power supply switch. The DC / DC converter is directly connected to the first battery, and power is supplied from the first battery. The second battery is supplied with power from the DC / DC converter and supplies a low voltage to the low voltage system via an ignition switch. The electronic control unit is directly connected to the second battery, detects that the ignition switch is not supplying power to the low voltage system, and controls start and stop of the DC / DC converter. Then, the second battery is charged so that the power supply switch can be switched.

  In addition, a vehicle power supply device according to another embodiment includes a first battery, a DC / DC converter, a second battery, and an electronic control unit. The first battery supplies a high voltage to the high voltage system via a power supply switch.

  The DC / DC converter is directly connected to supply power to the first battery, and detects that the ignition switch is not supplying power to the low-voltage system. Then, the measurement of time is started and activated when the measured value falls outside the range of the fourth threshold, and stopped when the measured value falls outside the range of the fifth threshold, and the measured value is set to the initial value. The DC / DC charging control process is repeatedly executed. Thereafter, when it is detected that the ignition switch is in a state of supplying power to the low voltage system, the DC / DC charging control process is stopped.

  The second battery is supplied with power from the DC / DC converter, and supplies a low voltage to the low voltage system via the ignition switch. The electronic control unit is directly connected to the second battery and switches the power supply switch.

  In addition, a vehicle power supply device according to another embodiment includes a first battery, a DC / DC converter, a second battery, and an electronic control unit. The first battery supplies a high voltage to the high voltage system via a power supply switch. The first battery supplies a high voltage to the high voltage system via a power supply switch.

  The DC / DC converter is directly connected to supply power to the first battery, the ignition switch is supplying power to the low voltage system, and the charging voltage of the second battery is charged. It starts when it detects that it is below the threshold for use. Then, the second battery is charged so that the power supply switch can be switched.

  The second battery is supplied with power from the DC / DC converter, and supplies a low voltage to the low voltage system via the ignition switch. The electronic control unit is directly connected to the second battery and switches the power supply switch.

  According to another aspect of the vehicle power supply apparatus, the first battery, the DC / DC converter, and the power supply switch are arranged in the same battery pack casing.

  The embodiment has an effect that it is possible to prevent insufficient charging of a low voltage battery connected to a subsequent stage of the DC / DC converter.

FIG. 3 is a block diagram illustrating an example of the power supply device according to the first embodiment. FIG. 6 is a flowchart illustrating an example of the operation of the power supply device according to the first embodiment. 3 is a time chart illustrating an example of an operation of the power supply device according to the first embodiment. FIG. 10 is a flowchart illustrating an example of the operation of the power supply device according to the second embodiment. 6 is a time chart illustrating an example of the operation of the power supply device according to the second embodiment. FIG. 10 is a flowchart illustrating an example of the operation of the power supply device according to the third embodiment. 10 is a time chart illustrating an example of the operation of the power supply device according to the third embodiment. It is a block diagram which shows one Example of the power supply device of Embodiment 4. FIG. 10 is a flowchart illustrating an example of the operation of the power supply device according to the fourth embodiment. 10 is a time chart illustrating an example of operation of the power supply device according to the fifth exemplary embodiment.

Hereinafter, embodiments will be described in detail based on the drawings.
In Embodiment 1, the output terminal of the 1st battery which outputs the high voltage which supplies electric power to the driving inverter etc. which drive the electric motor which starts a vehicle, and the input terminal of a DC / DC converter are connected directly. Moreover, the output terminal which outputs the electric power of a DC / DC converter is connected to the input terminal of a 2nd battery. The second battery supplies low-voltage power to a control unit that controls a power supply switch used when power is supplied to a traveling inverter and the like and a load such as a wiper or a headlight mounted on the vehicle. Further, the control unit, which is an electronic control unit, is directly connected to the second battery, controls the start and stop of the DC / DC converter, and charges the second battery so that the power supply switch can be switched. When the electronic control unit to which power is supplied from the second battery detects that the ignition key is in the OFF state, the DC / DC directly connected to the second battery is charged to charge the second battery. The DC converter is controlled to start charging. With this control, the second battery can be charged with sufficient power to operate the electronic control unit and the load even when the ignition key is in the off state. As a result, problems due to insufficient charging of the second battery, such as an inability to operate the electronic control unit due to insufficient charging of the second battery, control of the power supply switch, and startup of the vehicle, are avoided. FIG. 1 is a block diagram showing an embodiment of a power supply device for a vehicle. The power supply device includes a first battery 1, a DC / DC converter 2, a second battery 3, a first electronic control unit 4, relays RL1, RL2, RL3, a resistor R1, and an ignition switch IG-SW. Hereinafter, the first electronic control unit 4 is referred to as a first ECU. Relays RL1 and RL2 are the power supply switches. In FIG. 1, a circuit including the resistor R1 and the relay RL3 is described. However, in the first embodiment, it is not always necessary.

  The first battery 1 is a battery that supplies power to a high voltage system such as a traveling inverter 6 that drives an electric motor, an air conditioner, and the like, and an air conditioner inverter 7, and is a lithium battery, for example. The positive output terminal and the negative output terminal of the first battery 1 are connected to the input terminals of the DC / DC converter 2 used for charging the second battery 3. The positive output terminal of the first battery 1 is connected to one terminal of the resistor R1 and one terminal of the relay RL1. The negative output terminal of the first battery 1 is connected to one terminal of the relay RL2. Further, in this example, the traveling inverter 6 and the air conditioner inverter 7 are shown between the other terminals of the relay RL1 and the relay RL2, but in actuality, the step-up DC / DC converter or the like is also connected to the relay RL1 and the relay RL1. It is connected between the other terminals of RL2. The other terminal of the resistor R1 is connected to one terminal of the relay RL3, and the other terminal of the relay RL3 is connected to the other terminal of the relay RL1.

  The DC / DC converter 2 charges the second battery 3 that supplies electric power to auxiliary devices such as the first electronic control unit 4, the second electronic control unit 8, and the load 9. One of the output terminals of the DC / DC converter 2 is connected to the terminal of the second battery 3, one terminal of the ignition switch IG-SW, and the power supply terminal of the first ECU 4. The other output terminal of the DC / DC converter 2 is connected to the ground. The DC / DC converter 2 includes an input terminal that detects an IG signal indicating the state of the ignition switch IG-SW. The second electronic control unit 8 is hereinafter referred to as a second ECU.

The ignition switch IG-SW is a switch or a relay that is switch-controlled according to the operation state of the ignition key.
The second battery 3 directly supplies power to the first ECU 4 without passing through the ignition switch IG-SW. Further, the second battery 3 supplies power to the low voltage system to which the second ECU 8 and the load 9 are connected via the ignition switch IG-SW. In this example, only the second ECU 8 and the load 9 are shown for convenience, but the second battery 3 actually supplies electric power to electric components such as wipers and headlights included in the load 9.

  The first ECU 4 includes a control unit and a recording unit, and controls switching of the ignition switch IG-SW and the power supply switch corresponding to the operation state of the ignition key. Further, the first ECU 4 detects the state of charge of the second battery 3, operates the DC / DC converter 2 connected to the first battery 1, and charges the second battery 3. Further, the first ECU 4 performs charge control for the second battery 3 and power supply control for the load 9. The control unit may use a central processing unit (CPU) or a programmable device (such as a field programmable gate array (FPGA) or a programmable logic device (PLD)). The recording unit records programs, tables, data, and the like. The recording unit is a memory such as a read only memory (ROM) or a random access memory (RAM). The recording unit may record data such as parameter values and variable values, and can also be used as a work area. Note that the first ECU 4 may perform control such as release of the door lock, monitoring of parking theft, vehicle security, and the like. The first ECU 4 includes an input terminal that detects an IG signal indicating the state of the ignition switch IG-SW. An input terminal for detecting the state of the ignition switch IG-SW is connected to the other side of the ignition switch IG-SW and also to the DC / DC converter 2. However, when starting and stopping the DC / DC converter 2 are controlled on the first ECU 4 side, it is not necessary to connect the IG signal to the DC / DC converter 2. Further, the first ECU 4 controls the relays RL1, RL2, and RL3, the RL1 drive signal, the RL2 drive signal, and the RL3 drive signal, and the DC / DC converter 2 that is a control signal for starting the DC / DC converter 2. An output terminal for outputting a DC activation permission signal is provided. Further, the first ECU 4 includes an input terminal for detecting a voltage value at point c. The output terminals that output the RL1 drive signal, the RL2 drive signal, and the RL3 drive signal are connected to the relays RL1, RL2, and RL3, respectively. An output terminal that outputs a DC / DC activation permission signal is connected to the DC / DC converter 2.

  The second ECU 8 performs vehicle braking control, brake system control, travel inverter 6 control, electric motor drive control, and the like. Further, the second ECU 8 performs control to display information collected as a result of self-diagnosis of the first ECU 4 and the second ECU 8 on a display device in front of the driver's seat, and the like.

Note that the first ECU 4 and the second ECU 8 may be connected via, for example, a controller area network (CAN) or the like, and may collectively control the vehicle.
The operation of the first ECU 4 will be described.

  The charge control when the ignition switch IG-SW is in the off state will be described with reference to FIGS. FIG. 2 is a flowchart illustrating an example of the operation according to the first exemplary embodiment. FIG. 3 is a time chart illustrating an example of the operation according to the first exemplary embodiment. FIG. 3 is an example of a time chart when the first ECU 4 controls the start and stop of the DC / DC converter 2.

  In step S1, the first ECU 4 detects that the vehicle has stopped and the ignition key inserted in the key cylinder has been removed and the IG signal has been switched from on to off, for example. In FIG. 3, the first ECU 4 detects that the ignition switch IG-SW has changed from the on state to the off state at the timing ta. Next, the first ECU 4 changes the DC / DC drive permission signal from the start state to the stop state in order to stop the DC / DC converter 2 or stop supplying power at the timing tb. In FIG. 3, the DC / DC drive permission signal is switched from the on state to the off state. When the DC / DC converter 2 acquires the DC / DC drive permission signal output at the timing tb, the DC / DC converter 2 stops or stops supplying power. In FIG. 3, the start-up state is the on state, and the power supply stop state indicates the off state. In this example, the state of the DC / DC drive permission signal and the DC / DC converter 2 changes at the timing tb. However, in actuality, after the DC / DC drive permission signal is acquired, the DC / DC converter 2 The state changes to a stopped state. As a result, the voltage value of the second battery 3 starts to decrease. In the example of FIG. 3, the voltage value at the point c in FIG. 1 begins to decrease.

  In step S2, the first ECU 4 starts time measurement. For example, the first ECU 4 performs measurement using a counter, a clock IC, or the like. In the example of FIG. 3, time measurement is started at the timing tb when the DC / DC drive permission signal changes from on to off. Thereafter, the first ECU 4 turns the relays RL1, RL2, and RL3 from on to off at the timing of tc in FIG. 3 to stop the power supply to the high voltage system, so that the RL1 drive signal, the RL2 drive signal, RL3 The state of the drive signal is changed from on to off.

  In step S3, the first ECU 4 determines whether the IG signal is on or off. If it is off, the process proceeds to step S6 (Yes), and if it is on, the process proceeds to step S4 (No).

  In step S4, the first ECU 4 changes the state of the RL1 drive signal and the RL2 drive signal from on to off in order to turn on the relays RL1 and RL2. In step S5, the first ECU 4 activates the DC / DC converter 2. At that time, the first ECU 4 clears a count value or time such as a counter or a clock IC. In the example of FIG. 3, the first ECU 4 detects that the ignition switch IG-SW has changed from the OFF state to the ON state at timing te, and changes the state of the IG signal from OFF to ON at timing tf. Next, at timing tg, the first ECU 4 changes the state of the RL2 drive signal from off to on in order to turn on the relay RL2. Thereafter, at timing th, the first ECU 4 changes the state of the RL1 drive signal from off to on in order to turn on the relay RL1. Here, in FIG. 3, the first ECU 4 changes the state of the RL3 drive signal from OFF to ON to turn on the relay RL3 at timing tg, and the RL3 drive signal to turn OFF the relay RL3 at timing th. The state of is changed from on to off. By controlling relay RL3 as described above, first battery 1 starts to supply voltage to the high-voltage system via resistor R1 at timing tg. Then, at a timing th at which the voltage value reaches a predetermined voltage value, the relay RL3 is turned off and the relay RL1 is turned on, thereby preventing a large current from flowing through the high voltage system. In this example, the resistor R1 and the relay RL3 are used, but other methods may be used. Next, the first ECU 4 activates the DC / DC converter 2 at the timing ti. In this example, the first ECU 4 changes the DC / DC drive permission signal from the off state to the on state, and puts the DC / DC converter 2 into an activated state. In addition, after finishing the process of step S5, 1st ECU4 transfers to the operation mode after vehicle starting.

  In step S6, the measurement value which is the measurement result obtained by time measurement by the first ECU 4 is referred to and compared with the first threshold value T1 recorded in advance, and if it is within the range of the first threshold value T1, step is performed. The process proceeds to S3 (No), and if it is outside the range of the threshold value T1, the process proceeds to Step S7 (Yes). That is, if the measurement result has passed the first threshold value T1, the process proceeds to step S7.

  In step S7, the first ECU 4 changes the DC / DC drive permission signal from the off state to the on state in order to activate the DC / DC converter 2. For example, the first ECU 4 activates the DC / DC converter 2 by turning on the DC / DC drive permission signal at the timing tj in FIG. When the DC / DC converter 2 receives the DC / DC drive permission signal and starts up, power is supplied to the second battery 3 and the voltage value at the point c in FIG. 1 begins to rise.

  In step S8, the first ECU 4 determines whether the IG signal is on or off. If it is off, the process proceeds to step S11 (Yes), and if it is on, the process proceeds to step S9 (No). In step S9, the relays RL1 and RL2 are turned on, and in step S10, the DC / DC converter 2 is activated. Since the processes in steps S9 and S10 are the same as those in steps S4 and S5, a description thereof will be omitted.

  In step S11, the measurement value which is the measurement result obtained by time measurement by the first ECU 4 is referred to and compared with the second threshold value T2 recorded in advance. If it is within the range of the second threshold value T2, the step is performed. The process proceeds to S8 (No), and if it is out of the range of the second threshold T2, the process proceeds to Step S12 (Yes). That is, if the measurement result has passed the second threshold value T2, the process proceeds to step S12.

  In step S12, the first ECU 4 changes the DC / DC drive permission signal from the on state to the off state in order to stop the DC / DC converter 2. For example, the first ECU 4 turns off the DC / DC drive permission signal at the timing tk in FIG. 3 to stop the DC / DC converter 2. When the DC / DC converter 2 receives the DC / DC drive permission signal and stops, the power supply to the second battery 3 is stopped and the voltage value at the point c in FIG. 1 starts to decrease. When the process of step S12 is completed, the process proceeds to step S2. When the ignition switch IG-SW remains off, the second battery 3 is charged by repeatedly starting and stopping the DC / DC converter 2 at timings tl, tm, tn, and to.

  According to the first embodiment, the output terminal of the first battery 1 and the input terminal of the DC / DC converter 2 are directly connected, and the output terminal of the DC / DC converter 2 is connected to the input terminal of the second battery 3. ing. The first ECU 4 to which electric power is supplied from the second battery 3 controls the DC / DC converter 2 in order to charge the second battery 3, and the first ECU 4 is connected to the second battery 3. Sufficient power for operating the load 9 is supplied from the DC / DC converter 2. As a result, problems due to insufficient charging of the second battery, such as the relays RL1 and RL2 being unable to be controlled due to insufficient charging of the second battery 3 and the vehicle being unable to start, are avoided. Further, even when the ignition key is off, the DC / DC converter 2 is activated and the second battery 3 can be charged. Further, the second battery 3 is supplied with timely power from the DC / DC converter 2 regardless of the state of the relays RL1 and RL2. Therefore, the second battery 3 is not required to be charged with a large capacity as in the prior art. It is possible to reduce the charging capacity and reduce the size.

Embodiment 2 will be described.
In the second embodiment, unlike the first embodiment, a control unit is provided in the DC / DC converter 2, and the control unit acquires the IG signal and the DC / DC drive permission signal from the first ECU 4, and the DC / DC The start and stop of the converter 2 are controlled. The control unit of the DC / DC converter 2 may be a CPU or a programmable device. The second embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing an example of the operation of the second embodiment. FIG. 5 is a time chart showing an example of the operation of the first embodiment, and is an example of a time chart when the DC / DC converter 2 controls starting and stopping by the control unit included in the DC / DC converter 2. is there. In step S401, for example, the first ECU 4 detects that the vehicle has stopped and the ignition key inserted in the key cylinder has been removed, and the IG signal has been switched from on to off. Since the process of step S401 is the same as that of step S1 of the first embodiment, the description thereof is omitted.

  In step S402, the first ECU 4 instructs the DC / DC converter 2 to start time measurement. The DC / DC converter 2 acquires an instruction from the first ECU 4 and starts time measurement. For example, it is conceivable that the control unit of the DC / DC converter 2 performs measurement using a counter or a clock IC provided in the control unit. In the example of FIG. 5, time measurement is started at the timing tb when the DC / DC drive permission signal changes from on to off. After that, the first ECU 4 turns the relays RL1, RL2, and RL3 from on to off at the timing of tc in FIG. 5 to stop the power supply to the high voltage system, so that the RL1 drive signal, the RL2 drive signal, RL3 The state of the drive signal is changed from on to off.

  In step S403, the first ECU 4 determines whether the IG signal is on or off. If it is off, the process proceeds to step S406 (Yes), and if it is on, the process proceeds to step S404 (No).

  In step S404, the first ECU 4 turns on the relays RL1 and RL2, and in step S405, the first ECU 4 activates the DC / DC converter 2 and stops the time measurement of the DC / DC converter 2. . At that time, the control unit of the DC / DC converter 2 clears the count value or time of the counter of the control unit or the clock IC. In the example of FIG. 5, the first ECU 4 detects that the ignition switch IG-SW has changed from the off state to the on state at timing te, and changes the state of the IG signal from off to on at timing tf. Next, at timing tg, the first ECU 4 changes the state of the RL2 drive signal from off to on in order to turn on the relay RL2. Thereafter, at timing th, the first ECU 4 changes the state of the RL1 drive signal from off to on in order to turn on the relay RL1. Here, in FIG. 5, the first ECU 4 changes the state of the RL3 drive signal from OFF to ON to turn on the relay RL3 at timing tg, and the RL3 drive signal to turn off the relay RL3 at timing th. The state of is changed from on to off. By controlling relay RL3 as described above, first battery 1 starts to supply voltage to the high-voltage system via resistor R1 at timing tg. Then, at a timing th at which the voltage value reaches a predetermined voltage value, the relay RL3 is turned off and the relay RL1 is turned on, thereby preventing a large current from flowing through the high voltage system. In this example, the resistor R1 and the relay RL3 are used, but other methods may be used. Next, the first ECU 4 activates the DC / DC converter 2 at the timing ti. In this example, the first ECU 4 changes the DC / DC drive permission signal from the off state to the on state, and puts the DC / DC converter 2 into an activated state. In addition, after finishing the process of step S405, 1st ECU4 transfers to the operation mode after vehicle starting.

  In step S406, the measured value, which is a measurement result obtained by time measurement by the DC / DC converter 2, is used for comparison with a previously recorded threshold value T3 (fourth threshold value). The process proceeds to S403 (No), and if it is out of the range of the threshold T3, the process proceeds to Step S407 (Yes). That is, if the measurement result has passed the threshold value T3, the process proceeds to step S407. Thereafter, the DC / DC converter 2 is activated in step S407.

  In step S408, the first ECU 4 determines whether the state of the IG signal is on or off. If it is off, the process proceeds to step S411 (Yes), and if it is on, the process proceeds to step S409 (No). To do. In step S409, the relays RL1 and RL2 are turned on, and in step S410, the DC / DC converter 2 is activated. Since the processes in steps S409 and S410 are the same as those in steps S404 and S405, description thereof will be omitted.

  In step S411, the measurement value which is the measurement result obtained by the time measurement by the DC / DC converter 2 is referred to and compared with a threshold value T4 (fifth threshold value) recorded in advance. The process proceeds to step S408 (No), and if it is outside the range of the threshold T4, the process proceeds to step S412 (Yes). That is, if the measurement result has passed the threshold value T4, the process proceeds to step S412.

  In step S412, the DC / DC converter 2 is stopped. For example, the DC / DC converter 2 is stopped at the timing tk in FIG. When the DC / DC converter 2 stops, the power supply to the second battery 3 is stopped and the voltage value at the point c in FIG. 1 begins to decrease. When the process of step S412 ends, the process proceeds to step S402. When the ignition switch IG-SW remains off, the second battery 3 is charged by repeatedly starting and stopping the DC / DC converter 2 at timings tl, tm, tn, and to.

  According to the second embodiment, when it is detected that the ignition switch IG-SW is not supplying power to the low voltage system, the time measurement is started, and the measured value falls outside the fourth threshold range. The DC / DC converter 2 is activated. When the measured value falls outside the fifth threshold range, the DC / DC charging control process is repeatedly executed to stop and measure the measured value as an initial value, and the ignition switch IG-SW supplies power to the low voltage system. DC / DC charge control processing is stopped when it is detected that it is in a state to perform.

  According to the second embodiment, the output terminal of the first battery 1 and the input terminal of the DC / DC converter 2 are directly connected, and the output terminal of the DC / DC converter 2 is connected to the input terminal of the second battery 3. ing. The DC / DC converter 2 supplies the second battery 3 with enough power to operate the first ECU 4 and the load. As a result, problems due to insufficient charging of the second battery 3, such as the relays RL1 and RL2 being unable to be controlled due to insufficient charging of the second battery 3 and the vehicle being unable to start, are avoided. Further, even when the ignition key is off, the DC / DC converter 2 is activated and the second battery 3 can be charged. Further, the second battery 3 is supplied with timely power from the DC / DC converter 2 regardless of the state of the relays RL1 and RL2. Therefore, the second battery 3 is not required to be charged with a large capacity as in the prior art. It is possible to reduce the charging capacity and reduce the size.

Further, the auxiliary system dark current (current consumption) of the low voltage system when the ignition switch IG-SW is off can be kept low.
A third embodiment will be described.

  Charging control when the ignition switch IG-SW is in the off state will be described with reference to FIGS. FIG. 6 is a flowchart showing an example of the operation of the third embodiment. FIG. 7 is a time chart showing an example of the operation of the third embodiment. FIG. 7 is an example of a time chart when the first ECU 4 controls the start and stop of the DC / DC converter 2.

  In step S601, the first ECU 4 detects that the vehicle has stopped and the ignition key inserted in the key cylinder has been removed and the IG signal has been switched from on to off, for example. Since the process of step S601 is the same as that of step S1 of the first embodiment, the description thereof is omitted.

  In step S602, the first ECU 4 starts monitoring the voltage value at the point c in FIG. In the example of FIG. 7, monitoring of the voltage value at the point c is started at the timing tb when the DC / DC drive permission signal changes from on to off. After that, the first ECU 4 turns the relays RL1, RL2, and RL3 from on to off at the timing of tc in FIG. 7 to stop the power supply to the high voltage system, so that the RL1 drive signal, the RL2 drive signal, RL3 The state of the drive signal is changed from on to off.

  In step S603, the first ECU 4 determines whether the IG signal is on or off. If it is off, the process proceeds to step S606 (Yes), and if it is on, the process proceeds to step S604 (No).

  In step S604, the first ECU 4 changes the state of the RL1 drive signal and the RL2 drive signal from on to off in order to turn on the relays RL1 and RL2. In step S605, the first ECU 4 activates the DC / DC converter 2. At that time, the first ECU 4 clears a count value or time such as a counter or a clock IC. In the example of FIG. 7, the first ECU 4 detects that the ignition switch IG-SW has changed from the off state to the on state at the timing te, and changes the state of the IG signal from off to on at the timing tf. Next, at timing tg, the first ECU 4 changes the state of the RL2 drive signal from off to on in order to turn on the relay RL2. Thereafter, at timing th, the first ECU 4 changes the state of the RL1 drive signal from off to on in order to turn on the relay RL1. Here, in FIG. 7, the first ECU 4 changes the state of the RL3 drive signal from OFF to ON to turn on the relay RL3 at timing tg, and the RL3 drive signal to turn OFF the relay RL3 at timing th. The state of is changed from on to off. By controlling relay RL3 as described above, first battery 1 starts to supply voltage to the high-voltage system via resistor R1 at timing tg. Then, at a timing th at which the voltage value reaches a predetermined voltage value, the relay RL3 is turned off and the relay RL1 is turned on, thereby preventing a large current from flowing through the high voltage system. In this example, the resistor R1 and the relay RL3 are used, but other methods may be used. Next, the first ECU 4 activates the DC / DC converter 2 at the timing ti. In this example, the first ECU 4 changes the DC / DC drive permission signal from the off state to the on state, and puts the DC / DC converter 2 into an activated state. In addition, after finishing the process of step S605, 1st ECU4 transfers to the operation mode after vehicle starting.

  In step S606, the first ECU 4 refers to the voltage value at point c, which is the measurement result, and compares it with a pre-recorded threshold value for charging, and the voltage value at point c is determined from the charging threshold value. If it is a high value, it will transfer to step S602 (No). And if it is below the threshold value for charge, it will transfer to step S607 (Yes).

  In step S607, the first ECU 4 changes the DC / DC drive permission signal from the off state to the on state in order to activate the DC / DC converter 2. For example, the first ECU 4 activates the DC / DC converter 2 by turning on the DC / DC drive permission signal at the timing tj in FIG. When the DC / DC converter 2 receives the DC / DC drive permission signal and starts up, power is supplied to the second battery 3 and the voltage value at the point c in FIG. 1 begins to rise.

  In step S608, the first ECU 4 determines whether the IG signal is on or off. If it is off, the process proceeds to step S611 (Yes), and if it is on, the process proceeds to step S609 (No). In step S609, the relays RL1 and RL2 are turned on, and in step S610, the DC / DC converter 2 is activated. Since the processing in steps S609 and S610 is the same as that in steps S604 and S605, the description thereof is omitted.

  In step S611, the measurement value which is the measurement result obtained by time measurement by the first ECU 4 is referred to and compared with a threshold value T5 (third threshold value) recorded in advance. The process proceeds to S608 (No), and if it is out of the range of the threshold T5, the process proceeds to Step S612 (Yes). That is, if the measurement result has passed the threshold value T5, the process proceeds to step S612. In this example, the time is measured, but when a voltage value indicating that charging of the second battery 3 is completed is set in advance and it is detected that the voltage value is set, step S612 ( Yes).

  In step S612, the first ECU 4 changes the DC / DC drive permission signal from the on state to the off state in order to stop the DC / DC converter 2. For example, the first ECU 4 turns off the DC / DC drive permission signal at the timing tk in FIG. 7 to stop the DC / DC converter 2. When the DC / DC converter 2 receives the DC / DC drive permission signal and stops, the power supply to the second battery 3 is stopped and the voltage value at the point c in FIG. 1 starts to decrease. When the process of step S612 is completed, the process proceeds to step S602. When the ignition switch IG-SW remains off, the DC / DC converter 2 is repeatedly started and stopped at the timings tl, tm, tn, and to in FIG. 7 to charge the second battery 3. Do.

  According to the third embodiment, the output terminal of the first battery 1 and the input terminal of the DC / DC converter 2 are directly connected, and the output terminal of the DC / DC converter 2 is connected to the input terminal of the second battery 3. ing. The first ECU 4 to which electric power is supplied from the second battery 3 controls the DC / DC converter 2 in order to charge the second battery 3, and the first ECU 4 is connected to the second battery 3. Sufficient power is supplied from the DC / DC converter 2 to operate the load. As a result, problems due to insufficient charging of the second battery 3, such as the relays RL1 and RL2 being unable to be controlled due to insufficient charging of the second battery 3 and the vehicle being unable to start, are avoided. In addition, even when the ignition key is off, the DC / DC converter 2 is activated and the second battery can be charged. Further, the second battery 3 is supplied with timely power from the DC / DC converter 2 regardless of the state of the relays RL1 and RL2. Therefore, the second battery 3 is not required to be charged with a large capacity as in the prior art. It is possible to reduce the charging capacity and reduce the size.

A fourth embodiment will be described.
In the fourth embodiment, when the relays RL1 and RL2 cannot be turned on due to insufficient capacity of the second battery 3 even though the ignition switch IG-SW is turned on, the DC / DC converter 2 is turned on and the second battery is turned on. 3 is charged. FIG. 8 is a block diagram illustrating an example of a vehicle power supply device according to the fourth embodiment. The power supply device of Embodiment 4 includes a first battery 1, a DC / DC converter 2, a second battery 3, a first electronic control unit 4, a voltmeter 5, relays RL1, RL2, and an ignition switch IG-SW. ing. Hereinafter, the first electronic control unit 4 is referred to as a first ECU. Relays RL1 and RL2 are the power supply switches. Further, although a circuit including the resistor R1 and the relay RL3 is illustrated in FIG. 8, it is not always necessary in the fourth embodiment. Hereinafter, the voltmeter 5 is referred to as VH5.

  The difference from FIG. 1 is that VH5 is provided between abs of the high voltage system in FIG. 8, and the first ECU 4 includes an input terminal for acquiring a voltage value between VH5 and ab. Further, the first ECU 4 and the DC / DC converter 2 have a function of detecting a voltage value at a point d in FIG.

  Embodiment 4 will be described with reference to FIGS. 9 and 10. FIG. 9 is a flowchart showing an example of the operation of the power supply device for a vehicle in the fourth embodiment. FIG. 10 is a time chart showing an example of the operation of the fourth embodiment. In step S901, the ignition switch IG-SW changes from the off state to the on state, and in step S902, the first ECU 4 and the DC / DC converter 2 detect. In FIG. 8, the ignition switch IG-SW changes from the off state to the on state at the timing of tp. Thereafter, the state of the ignition switch IG-SW is reflected in the IG signal at the timing tq.

  In step S903, when the DC / DC converter 2 detects that the voltage value at the point d in FIG. 8 has changed due to the ignition switch IG-SW being turned on, the DC / DC converter 2 is activated. That is, when the detection function of the DC / DC converter 2 detects that the IG signal is on at the timing tq in FIG. 10, the DC / DC converter 2 is activated at the timing tq. Then, the DC / DC converter 2 supplies electric power to the second battery 3, and the first ECU 4 becomes ready to start. In this example, after the tr timing, the first ECU 4 is charged to a voltage value (first ECU drive threshold) that can be driven, and the first ECU 4 detects that the IG signal is in an on state and detects DC / The state of the DC drive permission signal is turned on.

  In step S904, the first ECU 4 compares the voltage value at the point c in FIG. 8 with the c voltage threshold value (threshold value for charging), and if it is equal to or greater than the c voltage threshold value, the process proceeds to step S905 (Yes). When the voltage value is lower than the threshold value, the process proceeds to step S904 (No). In this example, the voltage value at the point c in FIG.

  In step S905, the first ECU 4 changes the state of the RL2 drive signal and the RL3 drive signal from off to on in order to turn on the relays RL2 and RL3. In this example, the relays RL2 and RL3 are turned on at the timing ts.

  In step S906, the first ECU 4 determines whether or not the voltage of the high voltage system is a predetermined voltage value. The voltage value of VH5 is compared with the VH threshold value recorded in advance, and if it is equal to or higher than the VH threshold value, the process proceeds to step S907 (Yes), and if the voltage value is lower than the VH threshold value, the process proceeds to step S906 (No). In this example, the voltage value of VH5 becomes equal to or higher than the VH threshold at timing tt.

  In step S907, the first ECU 4 changes the state of the RL3 drive signal from on to off in order to turn off the relay RL3, and changes the state of the RL1 drive signal from off to on in order to turn on the relay RL1. . In this example, the relay RL3 is turned off and RL1 is turned on at the timing of tu. By controlling the relay RL3 as described above, the first battery 1 starts to supply a predetermined voltage value to the high voltage system via the resistor R1 at the timing ts. Then, at the timing tt when the voltage value reaches a predetermined voltage value, the relay RL3 is turned off and the relay RL1 is turned on, thereby preventing a large current from flowing through the high voltage system.

In step S908, the first ECU 4 shifts to an operation mode after starting the vehicle.
According to the fourth embodiment, since the output terminal of the first battery 1 and the input terminal of the DC / DC converter 2 are directly connected, the relays RL1 and RL2 cannot be controlled due to insufficient charging of the second battery 3, and the vehicle Inconveniences due to insufficient charging of the second battery 3 such as cannot be started are avoided. Further, even when the ignition key is on, the DC / DC converter 2 is activated and the second battery 3 can be charged. Further, the second battery 3 is supplied with timely power from the DC / DC converter 2 regardless of the state of the relays RL1 and RL2. Therefore, the second battery 3 is not required to be charged with a large capacity as in the prior art. It is possible to reduce the charging capacity and reduce the size.

  Note that the DC / DC converter 2 described in the first, second, third, and fourth embodiments is disposed in the same battery pack housing as the first battery 1 and the power supply switch. There is no need to check.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

1 first battery,
2 DC / DC converter,
3 second battery,
4 1st electronic control part, 1st ECU,
5 Voltmeter, VH,
6 Traveling inverter,
7 Air conditioner inverter,
8 Second electronic control unit, second ECU,
9 load,
R1 resistance,
RL1, RL2, RL3 relay,
IG-SW ignition switch

Claims (10)

A first battery for supplying a high voltage to a high voltage system;
A power supply switch provided between the high voltage system and the first battery;
A DC / DC converter connected directly to the first battery, connected between the first battery and the power supply switch, and supplied with power from the first battery;
A second battery which is supplied with power from the DC / DC converter and supplies a low voltage to the low voltage system via an ignition switch;
Directly connected to the second battery, and when the power switch is turned off to stop the power to the high voltage system, the DC / DC converter is controlled to start and stop, and the power switch A controller that charges the second battery in a switchable state;
A vehicle power supply apparatus comprising: When the control unit detects that the ignition switch is in a state of not supplying power to the low voltage system, the control unit controls start and stop of the DC / DC converter so that the power supply switch can be switched. Charging the second battery;
The power supply device for a vehicle according to claim 1. The control unit is an electronic control unit;
When it is detected that the ignition switch is not supplying power to the low-voltage system, time measurement is started. When the measured value is outside the first threshold range, the DC / DC converter is started and measurement is performed. When the measured value falls outside the range of the second threshold value, the DC / DC converter is stopped and the charge control process is repeatedly performed to set the measured value to the initial value, and the ignition switch supplies power to the low voltage system The power supply device for a vehicle according to claim 2, wherein the charging control process is stopped when it is detected that the vehicle is in a state. The control unit is an electronic control unit;
When the ignition switch detects that the power is not supplied to the low voltage system, and the charging voltage of the second battery falls below a charging threshold, the DC / DC converter is started and time is measured. And when the measured value falls outside the range of the third threshold value, the DC / DC converter is stopped and the charge control process is repeatedly executed to set the measured value to the initial value, and the ignition switch is connected to the low voltage system. The power supply device for a vehicle according to claim 2, wherein the charging control process is stopped when it is detected that power is being supplied to the vehicle. The control unit is an electronic control unit;
When the ignition switch detects that the power is not supplied to the low voltage system, and the charging voltage of the second battery falls below a charging threshold, the DC / DC converter is activated, and the second When the charging voltage of the battery falls within a threshold range indicating that the charging has been completed, the charging control process for stopping the DC / DC converter is repeatedly executed, and the ignition switch supplies power to the low voltage system. The power supply device for a vehicle according to claim 2, wherein the charging control process is stopped when it is detected that there is a certain event. The control unit is provided in the DC / DC converter,
When it is detected that the ignition switch is not supplying power to the low-voltage system, time measurement is started, and when the measured value is outside the fourth threshold range, the DC / DC converter is activated. When the measured value is out of the fifth threshold range, the DC / DC charging control process is repeatedly performed to stop and the measured value to be the initial value, and the ignition switch supplies power to the low voltage system The power supply apparatus for a vehicle according to claim 2, wherein the DC / DC charging control process is stopped when it is detected. The control unit is provided in the DC / DC converter,
When detecting that the ignition switch is supplying power to the low voltage system and the charging voltage of the second battery is equal to or lower than a charging threshold, the DC / DC converter is activated, The power supply device for a vehicle according to claim 2, wherein the second battery is charged in a state where the power supply switch can be switched.   The power supply device for a vehicle according to any one of claims 1 to 7, wherein the first battery, the DC / DC converter, and the power supply switch are arranged in a casing of the same battery pack. A first battery for supplying a high voltage to a high voltage system, a power supply switch provided between the high voltage system and the first battery, a direct connection to the first battery, and the first battery A DC / DC converter connected between the first battery and the power supply switch and supplied with power from the first battery; and supplied with power from the DC / DC converter; A second battery that supplies a low voltage via the power supply, and when the power supply switch is turned off to stop the power to the high voltage system, the start / stop of the DC / DC converter is controlled, A control unit for charging the second battery in a state in which the power supply switch can be switched,
The control unit is
When it detects that the ignition switch is in a state of not supplying power to the low voltage system, it starts measuring time,
When the measured value falls outside the first threshold range, the DC / DC converter directly connected to the first battery is activated,
When the measured value falls outside the range of the second threshold, the DC / DC converter is stopped and the measured value is set to the initial value, and the charge control process is repeated.
The charge control process is stopped when it is detected that the ignition switch is in a state of supplying power to the low voltage system;
A vehicle power supply control method that performs that. A first battery for supplying a high voltage to a high voltage system, a power supply switch provided between the high voltage system and the first battery, a direct connection to the first battery, and the first battery A DC / DC converter connected between the first battery and the power supply switch and supplied with power from the first battery; and supplied with power from the DC / DC converter; A second battery that supplies a low voltage via the power supply, and when the power supply switch is turned off to stop the power to the high voltage system, the start / stop of the DC / DC converter is controlled, A control unit for charging the second battery in a state in which the power supply switch can be switched,
The control unit is
When the ignition switch detects that the power is not supplied to the low voltage system, and detects that the charging voltage of the second battery is equal to or lower than a charging threshold, the DC / DC converter is activated. And start measuring time,
When the measured value falls outside the third threshold range, the DC / DC converter is stopped, and the measured value is set to the initial value, and the charge control process is repeated.
The charge control process is stopped when it is detected that the ignition switch is in a state of supplying power to the low voltage system;
A vehicle power supply control method that performs that.

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