JP4840197B2 - VEHICLE POWER DEVICE AND VEHICLE POWER DEVICE CONTROL METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit for vehicle and a method of suppressing the power unit for vehicle which reduce the energy loss, when a plurality of accumulators are loaded. <P>SOLUTION: A power unit for vehicle is equipped with batteries BA and BB1 which are a plurality of DC power sources for supplying power to a motor generator MG2 for driving a wheel, a plurality of voltage converters 39A and 39B which are respectively connected between the plurality of DC power sources and a common power line PL2 for voltage conversion, and a controller 30 which controls the plurality of voltage converters. The controller controls the plurality of voltage converters so that each power node of the plurality of DC power sources is connected to the common power node, after having reduced the power voltage difference of the plurality of DC power sources. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

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

  2. Description of the Related Art In recent years, vehicles that are equipped with a power supply device and drive a motor with electric power, such as electric vehicles, hybrid vehicles, and fuel cell vehicles, have attracted attention as environmentally friendly vehicles.

  In such a vehicle, it is also considered that the vehicle can be charged from the outside. In order to extend the distance that can be traveled by the charged electric power, it is necessary to increase the capacity of the power storage device. In order to increase the capacity of the power storage device, it is conceivable to use a large number of storage batteries connected in parallel, but variations in charging and discharging become a problem.

Japanese Patent Laying-Open No. 2002-10502 (Patent Document 1) discloses a storage battery charging / discharging device that simultaneously charges and discharges a plurality of storage batteries. This storage battery charging / discharging device is provided with a charging rectifier circuit for rectifying an AC power source, and a regenerative rectifier circuit for regenerating the amount of electricity of the storage battery to the AC power source in parallel with the charging rectifier circuit, Furthermore, a buck-boost converter having a switching element is provided at the output of the charging rectifier circuit.
JP 2002-10502 A JP-A-8-126121

  The back electromotive force of the motor increases as the rotational speed increases. If the power supply voltage of the motor is lower than the back electromotive force, controllability cannot be maintained. Controllability can be maintained by performing field-weakening control and keeping the back electromotive force lower than the motor power supply voltage, but the output torque is lowered accordingly. Therefore, in order to maintain the motor power supply voltage higher than the counter electromotive force and achieve both controllability and high output, the battery voltage is boosted by a boost converter and supplied to the motor.

  On the other hand, in the region where the rotational speed of the motor is low, the back electromotive force is sufficiently lower than the battery voltage, so there is no need to boost the voltage by a boost converter. The step-up converter has a switching element inside, and switching loss occurs when operated. Therefore, in a region where the rotational speed of the motor is low, it is desired to stop the switching of the boost converter and supply the battery voltage to the motor as it is.

  However, in the case where a plurality of power storage devices are mounted in parallel, if there is a difference in the power supply voltage of each power storage device, setting the boost converter to a short-circuited state results in a low voltage power storage device from a high voltage power storage device Excessive current will flow toward

  An object of the present invention is to provide a vehicle power supply apparatus and a vehicle power supply control method in which energy loss is reduced when a plurality of power storage devices are mounted.

  In summary, the present invention is a power supply device for a vehicle, and a plurality of DC power supplies for supplying power to a motor for driving wheels, and a voltage connected to each of a plurality of DC power supplies and a common power supply node. A plurality of voltage conversion units that perform conversion and a control device that controls the plurality of voltage conversion units. The control device controls the plurality of voltage conversion units so that the power supply nodes of the plurality of DC power supplies are connected to the common power supply node after reducing the difference between the power supply voltages of the plurality of DC power supplies.

  Preferably, the first voltage conversion unit of the plurality of voltage conversion units is configured to boost a voltage of the first DC power source among the plurality of DC power sources and supply the voltage to the common power supply node. , Including a first connection for connecting the first DC power source and the first boost converter. The first connection unit includes a first relay and a limiting resistor connected in series between the first DC power source and the first boost converter, the first DC power source, and the first boost converter. And a second relay that directly connects to each other. The control device releases the second relay and keeps the first relay connected until the voltage difference between the first DC power supply and the other DC power supply becomes a predetermined value or less. The second relay is controlled to be in a connected state after the difference in voltage between the DC power supplies becomes equal to or less than a predetermined value.

  Preferably, when the output request from the vehicle load to the vehicle power supply device is equal to or less than a predetermined value, the control device reduces a difference in the power supply voltages of the plurality of DC power supplies and supplies the vehicle power supply device from the vehicle load. When the output request is larger than the predetermined value, the power supply voltage of the corresponding DC power supply is boosted and output to the common power supply node by at least one of the plurality of voltage conversion units.

  Preferably, two DC power sources among the plurality of DC power sources are the first and second power storage devices. Each of the first and second voltage converters corresponding to the first and second power storage devices includes a switching element and a coil, respectively. The control device controls switching of each switching element of the plurality of voltage conversion units, so that the voltage difference between the first and second power storage devices decreases from one power storage device to the other power storage device. Transfer power.

  Preferably, two DC power sources among the plurality of DC power sources are the first and second power storage devices. Each of the first and second voltage converters corresponding to the first and second power storage devices is provided in parallel with the coil, a switching element provided between the common power supply node and the coil, and the switching element. A rectifier element and a current sensor for detecting a current flowing through the coil are included. The control device controls the switching element of one of the voltage conversion units corresponding to the higher power supply voltage of the first and second power storage devices to be in a conductive state, and the switching element of the other voltage conversion unit is in a non-conductive state When the current is detected by the current sensor of the other voltage conversion unit, it is determined that the difference between the power supply voltages of the first and second power storage devices has become a predetermined value or less.

  Preferably, at least one of the plurality of DC power supplies is a power storage device, and the power supply device of the vehicle further includes a power receiving unit that receives power from the external power supply in order to charge the power storage device from the external power supply.

  According to another aspect of the present invention, a plurality of DC power supplies for supplying power to a motor for driving a wheel, and a plurality of DC power supplies and a plurality of DC power supplies connected to a common power supply node, respectively, and perform voltage conversion. A method for controlling a power supply device for a vehicle comprising a voltage conversion unit, the first step of controlling a plurality of voltage conversion units so as to reduce a difference in power supply voltages of a plurality of DC power supplies, And a second step of controlling the plurality of voltage conversion units so that each power supply node of the plurality of DC power supplies is connected to the common power supply node when the difference between the power supply voltages becomes smaller than a predetermined value.

  Preferably, the first voltage conversion unit of the plurality of voltage conversion units is configured to boost a voltage of the first DC power source among the plurality of DC power sources and supply the voltage to the common power supply node. , Including a first connection for connecting the first DC power source and the first boost converter. The first connection unit includes a first relay and a limiting resistor connected in series between the first DC power source and the first boost converter, the first DC power source, and the first boost converter. And a second relay that directly connects to each other. The first step includes a step of keeping the second relay open until a voltage difference between the first DC power source and the other DC power source becomes a predetermined value or less, and the first DC power source and the other DC power source. Until the first voltage difference becomes equal to or less than a predetermined value. The second step includes a step of controlling the second relay to the connected state after the difference between the voltage of the first DC power source and the other DC power source becomes a predetermined value or less.

  Preferably, the control method further includes a step of determining whether an output request from the vehicle load to the power supply device of the vehicle is equal to or less than a threshold value. The first step is performed when the output request is below a threshold value.

  Preferably, two DC power sources among the plurality of DC power sources are the first and second power storage devices. Each of the first and second voltage converters corresponding to the first and second power storage devices includes a switching element and a coil, respectively. In the first step, from one power storage device to the other power storage device so as to reduce the voltage difference between the first and second power storage devices by controlling switching of each switching element of the plurality of voltage conversion units. In contrast, power is transferred.

  Preferably, two DC power sources among the plurality of DC power sources are the first and second power storage devices. Each of the first and second voltage converters corresponding to the first and second power storage devices is provided in parallel with the coil, a switching element provided between the common power supply node and the coil, and the switching element. A rectifier element and a current sensor for detecting a current flowing through the coil are included. The first step is a step of controlling the switching element of one of the voltage conversion units corresponding to the higher one of the first and second power storage devices to the conductive state, and the switching element of the other voltage conversion unit And a step of determining that the difference between the power supply voltages of the first and second power storage devices is equal to or less than a predetermined value when a current is detected by the current sensor of the other voltage converter. including.

  Preferably, at least one of the plurality of DC power supplies is a power storage device. The power supply device for a vehicle further includes a power receiving unit that receives power from the external power supply in order to charge the power storage device from the external power supply.

  According to the present invention, when a plurality of power storage devices are mounted, energy loss is reduced and efficient traveling can be realized.

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

FIG. 1 is a diagram showing a main configuration of a vehicle 1 according to an embodiment of the present invention.
Referring to FIG. 1, vehicle 1 includes batteries BA and BB1, which are power storage devices, voltage converters 39A and 39B, a smoothing capacitor CH, voltage sensors 10A and 10B1 and 13, inverters 14 and 22, Engine 4, motor generators MG <b> 1, MG <b> 2, power split mechanism 3, wheels 2, and control device 30 are included.

  Voltage converters 39A and 39B include boost converters 12A and 12B, smoothing capacitors C1 and C2, and voltage sensors 21A and 21B.

  The power storage device mounted on the vehicle can be charged from the outside. For this purpose, vehicle 1 further includes power input lines ACL <b> 1 and ACL <b> 2, relay circuit 51, input terminal 50, and voltage sensor 74.

  Relay circuit 51 includes relays RY1 and RY2. As relays RY1 and RY2, for example, mechanical contact relays can be used, but semiconductor relays may also be used. Then, one end of power input line ACL1 is connected to one end of relay RY1, and the other end of power input line ACL1 is connected to neutral point N1 of three-phase coil of motor generator MG1. Further, one end of power input line ACL2 is connected to one end of relay RY2, and the other end of power input line ACL2 is connected to neutral point N2 of the three-phase coil of motor generator MG2. Further, the input terminal 50 is connected to the other end of the relays RY1, RY2.

  Relay circuit 51 electrically connects input terminal 50 to power input lines ACL1 and ACL2 when input permission signal EN from control device 30 is activated. Specifically, relay circuit 51 turns on relays RY1, RY2 when input permission signal EN is activated, and turns off relays RY1, RY2 when input permission signal EN is deactivated.

  The input terminal 50 is a terminal for connecting the commercial power source 90 outside the vehicle to the hybrid vehicle 1. In this hybrid vehicle 1, the battery BA or BB 1 can be charged from a commercial power supply 90 connected to the input terminal 50 outside the vehicle.

  The above configuration uses the neutral point of the stator coil of the two rotating electrical machines. Instead of such a configuration, for example, in order to connect to a commercial power supply of AC 100V, An installed battery charging device may be used, or a method in which the boost converters 12A and 12B are combined to function as an AC / DC converter may be used.

  Smoothing capacitor C1 is connected between power supply line PL1A and ground line SL2. The voltage sensor 21 </ b> A detects the voltage VLA across the smoothing capacitor C <b> 1 and outputs it to the control device 30. Boost converter 12A boosts the voltage across terminals of smoothing capacitor C1.

  Smoothing capacitor C2 is connected between power supply line PL1B and ground line SL2. The voltage sensor 21B detects the voltage VLB across the smoothing capacitor C2 and outputs it to the control device 30. Boost converter 12B boosts the voltage across terminals of smoothing capacitor C2.

  Smoothing capacitor CH smoothes the voltage boosted by boost converters 12A and 12B. The voltage sensor 13 detects the inter-terminal voltage VH of the smoothing capacitor CH and outputs it to the control device 30.

  Inverter 14 converts the DC voltage applied from boost converter 12B or 12A into a three-phase AC voltage and outputs the same to motor generator MG1. Inverter 22 converts the DC voltage applied from boost converter 12B or 12A into a three-phase AC voltage and outputs the same to motor generator MG2.

  Power split device 3 is a mechanism that is coupled to engine 4 and motor generators MG1 and MG2 and distributes power between them. For example, as the power split mechanism, a planetary gear mechanism having three rotating shafts of a sun gear, a planetary carrier, and a ring gear can be used. In the planetary gear mechanism, if rotation of two of the three rotation shafts is determined, rotation of the other one rotation shaft is forcibly determined. These three rotation shafts are connected to the rotation shafts of engine 4 and motor generators MG1, MG2, respectively. The rotating shaft of motor generator MG2 is coupled to wheel 2 by a reduction gear and a differential gear (not shown). Further, a reduction gear for the rotation shaft of motor generator MG2 may be further incorporated in power split mechanism 3, or an automatic transmission may be incorporated.

  Voltage conversion unit 39A includes a connection unit 40A provided on the positive electrode side and a system main relay SMRG that is a connection unit provided on the negative electrode side. Connection unit 40A includes a system main relay SMRB connected between the positive electrode of battery BA and power supply line PL1A, a system main relay SMRP connected in series with system main relay SMRB, and a limiting resistor R0. Including. System main relay SMRG is connected between a negative electrode (ground line SL1) of battery BA and ground line SL2.

  System main relays SMRP, SMRB, and SMRG are controlled to be in a conductive / non-conductive state in response to control signals CONT1 to CONT3 supplied from control device 30, respectively.

  Voltage sensor 10A measures voltage VA between the terminals of battery BA. Although not shown, in order to monitor the charging state of the battery BA together with the voltage sensor 10A, a current sensor for detecting a current flowing through the battery BA is provided. As the battery BA, for example, a secondary battery such as a lead storage battery, a nickel metal hydride battery, or a lithium ion battery, or a large-capacity capacitor such as an electric double layer capacitor can be used.

  Voltage conversion unit 39B includes a connection part 40B provided on the positive electrode side and a system main relay SR1G which is a connection part provided on the negative electrode side. Connection unit 40B includes a system main relay SR1B connected between the positive electrode of battery BB1 and power supply line PL1B, a system main relay SR1P connected in series with system main relay SR1B, and a limiting resistor R1. Including. System main relay SR1G is connected between the negative electrode of battery BB1 and ground line SL2.

  System main relays SR1P, SR1B, and SR1G are controlled to be in a conductive / non-conductive state according to control signals CONT4 to CONT6 provided from control device 30, respectively.

  As will be described later, ground line SL2 extends through boost converters 12A and 12B to inverters 14 and 22 side.

  Voltage sensor 10B1 measures voltage VBB1 between the terminals of battery BB1. Although not shown, in order to monitor the charging state of the battery BB1 together with the voltage sensor 10B1, a current sensor for detecting a current flowing through each battery is provided. As the battery BB1, for example, a secondary battery such as a lead storage battery, a nickel metal hydride battery, or a lithium ion battery, or a large capacity capacitor such as an electric double layer capacitor can be used.

  Inverter 14 is connected to power supply line PL2 and ground line SL2. Inverter 14 receives the boosted voltage from boost converters 12A and 12B, and drives motor generator MG1 to start engine 4, for example. Inverter 14 returns the electric power generated by motor generator MG1 by the power transmitted from engine 4 to boost converters 12A and 12B. At this time, boost converters 12A and 12B are controlled by control device 30 so as to operate as a step-down circuit.

  Current sensor 24 detects the current flowing through motor generator MG1 as motor current value MCRT1, and outputs motor current value MCRT1 to control device 30.

  Inverter 22 is connected to power supply line PL2 and ground line SL2 in parallel with inverter 14. Inverter 22 converts the DC voltage output from boost converters 12 </ b> A and 12 </ b> B into a three-phase AC voltage and outputs the same to motor generator MG <b> 2 driving wheel 2. Inverter 22 returns the electric power generated in motor generator MG2 to boost converters 12A and 12B in accordance with regenerative braking. At this time, boost converters 12A and 12B are controlled by control device 30 so as to operate as a step-down circuit.

  Current sensor 25 detects the current flowing through motor generator MG2 as motor current value MCRT2, and outputs motor current value MCRT2 to control device 30.

  Control device 30 receives torque command values and rotational speeds of motor generators MG1, MG2, voltages VBA, VBB1, VBB2, VLA, VLB, VH, motor current values MCRT1, MCRT2, and start signal IGON. Control device 30 outputs a control signal PWUB for instructing boosting to boost converter 12B, a control signal PWDB for instructing step-down, and a shutdown signal for instructing prohibition of operation.

  Further, control device 30 provides control signal PWMI1 for instructing inverter 14 to convert a DC voltage, which is the output of boost converters 12A and 12B, into an AC voltage for driving motor generator MG1, and motor generator MG1. And outputs a control signal PWMC1 for instructing regeneration to convert the AC voltage generated in step S1 to a DC voltage and return it to the boost converters 12A and 12B.

  Similarly, control device 30 converts control signal PWMI2 for instructing inverter 22 to drive to convert DC voltage into AC voltage for driving motor generator MG2, and AC voltage generated by motor generator MG2 to DC voltage. A control signal PWMC2 for instructing regeneration to be converted and returned to the boost converters 12A and 12B is output.

FIG. 2 is a circuit diagram showing a detailed configuration of inverters 14 and 22 in FIG.
Referring to FIGS. 1 and 2, inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are connected in parallel between power supply line PL2 and ground line SL2.

  U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series between power supply line PL2 and ground line SL2, and diodes D3 and D4 connected in parallel with IGBT elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of IGBT element Q3, and the anode of diode D3 is connected to the emitter of IGBT element Q3. The cathode of diode D4 is connected to the collector of IGBT element Q4, and the anode of diode D4 is connected to the emitter of IGBT element Q4.

  V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series between power supply line PL2 and ground line SL2, and diodes D5 and D6 connected in parallel with IGBT elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of IGBT element Q5, and the anode of diode D5 is connected to the emitter of IGBT element Q5. The cathode of diode D6 is connected to the collector of IGBT element Q6, and the anode of diode D6 is connected to the emitter of IGBT element Q6.

  W-phase arm 17 includes IGBT elements Q7 and Q8 connected in series between power supply line PL2 and ground line SL2, and diodes D7 and D8 connected in parallel with IGBT elements Q7 and Q8, respectively. The cathode of diode D7 is connected to the collector of IGBT element Q7, and the anode of diode D7 is connected to the emitter of IGBT element Q7. The cathode of diode D8 is connected to the collector of IGBT element Q8, and the anode of diode D8 is connected to the emitter of IGBT element Q8.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of motor generator MG1. That is, motor generator MG1 is a three-phase permanent magnet synchronous motor, and one end of each of three coils of U, V, and W phases is connected to the midpoint. The other end of the U-phase coil is connected to a line UL drawn from the connection node of IGBT elements Q3 and Q4. The other end of the V-phase coil is connected to a line VL drawn from the connection node of IGBT elements Q5 and Q6. The other end of the W-phase coil is connected to a line WL drawn from the connection node of IGBT elements Q7 and Q8.

  1 also differs in that it is connected to motor generator MG2, but the internal circuit configuration is the same as that of inverter 14, and therefore detailed description thereof will not be repeated. FIG. 2 shows that the control signals PWMI and PWMC are given to the inverter, but this is for avoiding complicated description. As shown in FIG. 1, separate control signals PWMI1 are used. , PWMC1 and control signals PWMI2 and PWMC2 are input to inverters 14 and 22, respectively.

FIG. 3 is a circuit diagram showing a detailed configuration of boost converters 12A and 12B in FIG.
1 and 3, boost converter 12A includes a reactor L1 having one end connected to power supply line PL1A, and IGBT elements Q1, Q2 connected in series between power supply line PL2 and ground line SL2. And diodes D1, D2 connected in parallel to IGBT elements Q1, Q2, respectively.

  Reactor L1 has the other end connected to the emitter of IGBT element Q1 and the collector of IGBT element Q2. The cathode of diode D1 is connected to the collector of IGBT element Q1, and the anode of diode D1 is connected to the emitter of IGBT element Q1. The cathode of diode D2 is connected to the collector of IGBT element Q2, and the anode of diode D2 is connected to the emitter of IGBT element Q2.

  The boost converter 12B in FIG. 1 is different from the boost converter 12A in that it is connected to the power supply line PL1B instead of the power supply line PL1A. Does not repeat. FIG. 3 shows that the control signals PWU and PWD are given to the boost converter, but this is for the purpose of avoiding complicated description. As shown in FIG. PWUA and PWDA and control signals PWUB and PWDB are input to inverters 14 and 22, respectively.

  Here, with reference to FIG. 1 again, operations common to the embodiments of the present application will be described. The power supply device for a vehicle according to the present embodiment includes batteries BA and BB1, which are a plurality of DC power supplies for supplying power to motor generator MG2 for driving wheels, and a plurality of DC power supplies and a common power supply line PL2. A plurality of voltage conversion units 39A and 39B that are connected to perform voltage conversion and a control device 30 that controls the plurality of voltage conversion units are provided. The control device controls the plurality of voltage conversion units so that the power supply nodes of the plurality of DC power supplies are connected to the common power supply node after reducing the difference between the power supply voltages of the plurality of DC power supplies.

  After reducing the difference in power supply voltage, each power supply node of multiple DC power supplies is connected to a common power supply node, so that an excessive current flows from a DC power supply with a high power supply voltage to a DC power supply with a low power supply voltage at the time of connection. Is prevented.

[Embodiment 1]
FIG. 4 is a flowchart for explaining control on voltage conversion units 39A and 39B in the first embodiment of the present invention. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIGS. 1 and 4, when the processing of this flowchart is started, it is determined in step S1 whether or not there is an upper arm ON request. Upper arm refers to IGBT element Q1 of each of boost converters 12A and 12B. The upper arm ON request is to stop the switching of the IGBT elements Q1 and Q2 of the boost converter, fix the IGBT element Q1 which is the upper arm to the conductive state, and fix the IGBT element Q2 which is the lower arm to the non-conductive state. By doing so, the power supply line PL2 and the power supply line PL1A or PL1B are connected. When boosting is unnecessary, this is done to reduce switching loss and improve energy efficiency.

  For example, if the boost converter is switched when the energization current is 0 A, the power consumption is about 45 W. When this is in the upper arm ON state, the power consumption is 0 W. Further, when the boost converter is switched when the energization current is 20 A, the power consumption is about 100 W. When this is in the upper arm ON state, the power consumption is reduced to 25W.

However, the conditions under which boosting is unnecessary in the boost converter are limited.
FIG. 5 is a diagram for explaining conditions under which boosting is unnecessary in the boost converter.

  Referring to FIG. 5, the horizontal axis represents the motor rotation speed Nm (rpm), the waveform W1 represents the maximum motor power curve, and the vertical axis represents the motor torque Tm (N · m). The waveform W2 is a control value of the output voltage VH of the boost converter, and the vertical axis for this is VH (V).

  The back electromotive force of the motor increases as the rotational speed increases. However, the waveform W2 is the battery voltage VBAT (constant value) because the battery voltage is higher than the counter electromotive force for a while from 0 to Nm0.

  When the rotational speed increases and the back electromotive force exceeds the battery voltage VBAT, the output voltage VH of the boost converter is controlled to be higher than the back electromotive force as the rotational speed increases.

  However, there is a maximum value VMAX in the boost voltage of the boost converter. For this reason, after the rotational speed Nm1 at which the boosted voltage reaches VMAX, the boosted voltage indicated by the waveform W2 remains unchanged at VMAX even if the motor rotational speed Nm increases. In the region where the motor rotational speed Nm is larger than the rotational speed Nm1, field weakening control is performed as the rotational speed increases, so that the maximum torque gradually decreases as the rotational speed increases, as shown by the waveform W1.

  In FIG. 5, regions A1 and A2 are shown with the waveform W3 as a boundary. Region A1 is a region where the boost converter may be stopped and battery voltage VBAT may be applied to the inverter. Region A2 is a region where the battery voltage needs to be boosted by the boost converter. In step S1 in FIG. 4, it is determined whether the operating point determined by the motor rotation speed and torque in the current operating state of the vehicle belongs to the area A1 on the map in FIG. When the operating point belongs to the area A1, an upper arm ON request is generated.

  If it is determined in step S1 that there is an upper arm ON request, the process proceeds to step S2. In step S2, it is determined whether or not the required battery output value is equal to or less than the threshold value A (kW). In step S1, it is detected how much output the motor is requesting, whereas in step S2, in addition to the motor output request, output to the battery taking into account other power consumption (auxiliary equipment, etc.). A request is detected. This is because when a current is supplied through a limiting resistor as will be described later, heat loss increases when this required value is large.

  If the battery output request is equal to or less than the threshold value A (kw) in step S2, the process proceeds to step S3. In step S3, the battery voltage is checked. Here, the voltages of the battery BA and the battery BB1 may be measured, or the voltage of the battery that has been regularly measured in advance may be read from the memory.

  Subsequent to step S3, the process of step S4 is executed. In step S4, battery voltages VBA and VBB1 are compared.

  If VBA> VBB1 is satisfied in step S4, the process proceeds to step S5. In step S5, system main relay SR1P is changed from the OFF state to the ON state. In step S6, system main relay SR1B is changed from the ON state to the OFF state. As a result, the connection is changed so that current flows into and out of battery BB1 via limiting resistor R1.

  Further, in step S7, IGBT element Q1 which is the upper arm in each of boost converters 12A and 12B is controlled to be in the ON state. Then, the two batteries are connected via the limiting resistor R1, and charging is executed from the battery BA having the higher voltage to the battery BB1 having the lower voltage as shown in step S8.

  FIG. 6 is a circuit diagram for illustrating the state of charging performed in step S8 of FIG.

  As shown by current I in FIG. 6, when voltage VBA is higher than voltage VBB1, current I flows out from battery BA via system main relay SMRB and the upper arm of boost converter 12A, and the boost converter Current flows into battery BB1 via upper arm of 12B, system main relay SR1P, and limiting resistor R1.

  4 and 6 show an example in which the charging current is limited by the limiting resistor R1, instead, the charging current is limited by the limiting resistor R0, or both the limiting resistors R0 and R1 are used. The control may be modified so as to limit the current.

  Referring to FIG. 4 again, in step S9 following step S8, it is determined whether or not battery voltage VBA and battery voltage VBB1 are substantially equal. Actually, it is determined whether or not the absolute value of the difference between the battery voltage VBA and the battery voltage VBB1 is equal to or less than a predetermined threshold value. This predetermined threshold value is determined in consideration of the fact that no welding occurs due to spark when the system main relay SR1B is turned on, and that overheating exceeding the allowable value does not occur in components such as the capacitors C1, C2, and CH. The

  If the battery voltage VBA and the battery voltage VBB1 are not yet equal in step S9, the process returns to step S8 and the battery is continuously charged. On the other hand, if it is determined in step S9 that the battery voltage VBA and the battery voltage VBB1 are substantially equal, the process proceeds to step S10.

  In step S10, system main relay SR1B is changed from the OFF state to the ON state, and in step S11, system main relay SR1P is changed from the ON state to the OFF state. As a result, the connection is changed so that current is supplied from the battery BB1 without passing through the limiting resistor R1.

  On the other hand, if VBA> VBB1 is not satisfied in step S4, the process proceeds to step S15. In step S15, the system main relay SMRP is changed from the OFF state to the ON state. In step S16, system main relay SMRB is changed from the ON state to the OFF state. As a result, the connection is changed so that the current flows into and out of the battery BA through the limiting resistor R0.

  Further, in step S17, IGBT element Q1 which is the upper arm in each of boost converters 12A and 12B is controlled to be in the ON state. Then, the two batteries are connected via the limiting resistor R1, and charging is performed from the battery BB1 having a higher voltage to the battery BA having a lower voltage as shown in step S18.

  In step S19, it is determined whether or not battery voltage VBA and battery voltage VBB1 are substantially equal. Actually, it is determined whether or not the absolute value of the difference between the battery voltage VBA and the battery voltage VBB1 is equal to or less than a predetermined threshold value. The predetermined threshold value is determined in consideration of the fact that no welding occurs due to spark when the system main relay SMRB is turned on, and that overheating exceeding the allowable value does not occur in components such as the capacitors C1, C2, and CH. The

  If the battery voltage VBA and the battery voltage VBB1 are not yet equal in step S19, the process returns to step S18 and the battery is continuously charged. On the other hand, if it is determined in step S19 that the battery voltage VBA and the battery voltage VBB1 are substantially equal, the process proceeds to step S20.

  In step S20, system main relay SMRB is changed from the OFF state to the ON state, and in step S21, system main relay SMRP is changed from the ON state to the OFF state. As a result, the connection is changed so that current is supplied from the battery BA without passing through the limiting resistor R0.

  Finally, when the conditions of steps S1 and S2 are not satisfied, or when the processes of steps S11 and S21 are completed, the process proceeds to step S22, and the control is transferred to the main routine.

  Here, the operation in the first embodiment will be described with reference to FIG. 1 again. The first voltage converter 39A among the plurality of voltage converters boosts the voltage of the battery BA of the plurality of DC power supplies and supplies the boosted voltage to the common power line PL2, and the battery BA and the boost converter. 40A of connection parts which connect 12A are included. Connection unit 40A includes a system main relay SMRP and a limiting resistor R0 connected in series between battery BA and boost converter 12A, and a system main relay SMRB directly connecting battery BA and boost converter 12A. Including. The control device 30 releases the system main relay SMRB and keeps the system main relay SMRP connected until the voltage difference between the battery BA and the other DC power supply becomes a predetermined value or less, and the voltage between the battery BA and the other DC power supply is maintained. After the difference between the values becomes equal to or less than a predetermined value, the system main relay SMRB is controlled to be connected.

  Therefore, when there is a difference in power supply voltage between the battery BA and the battery BB1, the current is limited by the limiting resistor, and the current limitation is canceled after the power supply voltage becomes equal in that state. Thus, a plurality of batteries provided in parallel can be transitioned from a state where the current is controlled by the boost converter to a state directly connected to the load.

  When the output request from the vehicle load to the power supply device of the vehicle is equal to or less than a predetermined value (for example, when the operating point belongs to region A1 in FIG. 5), control device 30 determines the difference between the power supply voltages of the plurality of DC power supplies. Decrease. Further, when the output request from the vehicle load to the power supply device of the vehicle is greater than a predetermined value (for example, when the operating point belongs to region A2 in FIG. 5), control device 30 has at least voltage conversion units 39A and 39B. The power supply voltage of the corresponding battery is boosted by the boost converter included in any of the boosting converters and output to the common power supply line PL2. As a result, the efficiency of the power supply device for the vehicle at a low load with low rotation is improved.

[Embodiment 2]
In the first embodiment, the control is shown in which the battery is directly connected to the inverter after charging through the current limiting resistor provided in the system main relay portion. As another method, charging may be performed from a battery having a high voltage to a battery having a low voltage while controlling the current passing through the two boost converters to limit the current.

  FIG. 7 is a flowchart for illustrating control on voltage conversion units 39A and 39B in the second embodiment of the present invention. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIGS. 1 and 7, when the processing of this flowchart is started, it is determined in step S31 whether or not there is an upper arm ON request. Since the upper arm ON request is the same as in the first embodiment, description thereof will not be repeated.

  If there is an upper arm ON request in step S31, the process proceeds to step S32. In step S32, the battery voltage is checked. Here, the voltages of the battery BA and the battery BB1 may be measured, or the voltage of the battery that has been regularly measured in advance may be read from the memory.

  Following step S32, the process of step S33 is executed. In step S33, the battery voltages VBA and VBB1 are compared.

  If VBA> VBB1 is satisfied in step S33, the process proceeds to step S34. In step S34, boost converters 12A and 12B are controlled such that charging is performed from battery BA having the higher voltage to battery BB1 having the lower voltage at an appropriate rate. At this time, the charging current is limited by controlling the switching duty ratio of the switching elements of boost converters 12A and 12B.

  In step S35, it is determined whether or not battery voltage VBA and battery voltage VBB1 are substantially equal. Actually, it is determined whether or not the absolute value of the difference between the battery voltage VBA and the battery voltage VBB1 is equal to or less than a predetermined threshold value. The predetermined threshold value is determined in consideration of the fact that overheating exceeding the allowable value does not occur in components such as capacitors C1, C2, and CH.

  If the battery voltage VBA and the battery voltage VBB1 are not yet equal in step S35, the process returns to step S34 and the battery is continuously charged. On the other hand, if it is determined in step S35 that the battery voltage VBA and the battery voltage VBB1 are substantially equal, the process proceeds to step S38.

  On the other hand, if VBA> VBB1 is not satisfied in step S33, the process proceeds to step S36. In step S36, boost converters 12A and 12B are controlled so that battery BB1 having a higher voltage is charged to battery BA having a lower voltage at an appropriate rate. At this time, the charging current is limited by controlling the switching duty ratio of the switching elements of boost converters 12A and 12B.

  In step S37, it is determined whether or not battery voltage VBA and battery voltage VBB1 are substantially equal. Actually, it is determined whether or not the absolute value of the difference between the battery voltage VBA and the battery voltage VBB1 is equal to or less than a predetermined threshold value. The predetermined threshold value is determined in consideration of the fact that overheating exceeding the allowable value does not occur in components such as capacitors C1, C2, and CH.

  If the battery voltage VBA and the battery voltage VBB1 are not yet equal in step S37, the process returns to step S36 and the battery is continuously charged. On the other hand, if it is determined in step S37 that the battery voltage VBA and the battery voltage VBB1 are substantially equal, the process proceeds to step S38.

  In step S38, IGBT element Q1 which is the upper arm in each of boost converters 12A and 12B is controlled to be in the ON state. As a result, the two batteries are directly connected to the inverter (but via the reactor), so that the switching loss in the boost converter is reduced thereafter.

  If there is no upper arm ON request in step S31 and if the process of step S38 is completed, the process proceeds to step S39 and the control is moved to the main routine.

  Here, the operation in the second embodiment will be described with reference to FIG. 1 again. In the second embodiment, two DC power sources out of the plurality of DC power sources are batteries BA and BB1, which are power storage devices. Each of voltage converters 39A and 39B corresponding to batteries BA and BB1 includes an IGBT element Q1 and a reactor L1, which are switching elements. Control device 30 controls the switching of each switching element of voltage converters 39A and 39B to transfer power from one battery to the other so that the voltage difference between batteries BA and BB1 decreases.

  In the second embodiment, the same effect as in the first embodiment can be obtained, and the mechanical connection change as in the first embodiment is not involved. Control is possible.

[Embodiment 3]
In the third embodiment, an example will be described in which the power of a battery having a high voltage is consumed by a load to equalize the voltages. At that time, a current sensor is used to increase voltage detection accuracy.

  FIG. 8 is a flowchart for explaining control in the third embodiment. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIGS. 1 and 8, when the processing of this flowchart is started, it is first determined in step S51 whether or not there is an upper arm ON request. Since the upper arm ON request is the same as in the first and second embodiments, description thereof will not be repeated.

  If there is an upper arm ON request in step S51, the process proceeds to step S52. In step S52, the battery voltage is checked. Here, the voltages of the battery BA and the battery BB1 may be measured, or the voltage of the battery that has been regularly measured in advance may be read from the memory.

  Following step S52, the process of step S53 is executed. In step S53, the battery voltages VBA and VBB1 are compared.

  If VBA> VBB1 is satisfied in step S53, the process proceeds to step S54. In step S54, the upper arm (IGBT element Q1) of boost converter 12A connected to the battery side where the voltage is high is controlled to be in an ON state. In step S55, the upper and lower arms (IGBT elements Q1, Q2) of boost converter 12B are both controlled to be in the OFF state. Thereby, first, a current is supplied to the load from the battery BA having a high voltage. Note that the order of step S54 and step S55 may be interchanged. Further, since the diode D1 is present and current is supplied using the diode D1, the upper and lower arms may be controlled to be in the OFF state as in step S55.

  In step S56 following step S55, power is consumed by a load such as a motor or an air conditioner when the vehicle is running. Then, the power of the battery with the higher voltage is consumed, and the battery voltage is lowered accordingly.

  In step S57, it is detected that the current from battery BB1 having the lower voltage starts to flow through diode D1 of boost converter 12B.

FIG. 9 is a circuit diagram for explaining a current flow in the third embodiment.
8 and 9, in boost converter 12A, the upper arm (element Q1A) is controlled to be in the ON state, and the lower arm (element Q2A) is controlled to be in the OFF state. In boost converter 12B, both the upper arm (element Q1B) and the lower arm (element Q2B) are controlled to be in the OFF state. While the voltage VBA is still higher than the voltage VBB1, a reverse voltage is applied to the diode D1B, so that the current IBB1 does not flow and only the current IBA flows. This state is detected by the current sensors 100A and 100B.

  In step S57, it is determined whether or not current IBB> 0 (A) and current starts to flow. If the current IBB has not yet started to flow, the process returns to step S56 to further consume the power of the battery BA.

  If the voltage of the battery BA decreases as much as the battery BB1 as a result of consuming the power of the battery BA, it is detected in step S57 that the current IBB> 0 (A) and the current starts to flow. Then, the process proceeds from step S57 to step S58, and the upper arm (Q1) of boost converter 12B is controlled to be on.

Thereafter, the battery BB1 also supplies power to the load.
On the other hand, if VBA> VBB1 is not satisfied in step S53, the process proceeds to step S64. In step S64, the upper arm (IGBT element Q1) of boost converter 12B connected to the battery side where the voltage is high is controlled to be in an ON state. Subsequently, in step S65, both the upper and lower arms (IGBT elements Q1, Q2) of boost converter 12A are controlled to be in the OFF state. Thereby, first, a current is supplied to the load from the battery BB1 having a high voltage. Note that the order of step S64 and step S65 may be interchanged. In addition, since the diode D1 exists and the current is supplied by using the diode D1, the upper and lower arms may be controlled to be in the OFF state as in step S65.

  In step S66 following step S65, power is consumed by a load such as a motor or an air conditioner when the vehicle is traveling. Then, the power of battery BB1 with the higher voltage is consumed, and battery voltage VBB1 decreases accordingly.

  In step S67, it is detected using current sensor 100A that the current from battery BA having the lower voltage starts to flow through diode D1 of boost converter 12B.

  In step S67, it is determined whether or not current IBA> 0 (A) and current starts to flow. If the current IBA has not yet started to flow, the process returns to step S66 and the power of the battery BB1 is further consumed.

  If the voltage of the battery BA drops to the same level as the battery BA as a result of the power consumption of the battery BB1, it is detected in step S67 that the current IBA> 0 (A) and the current starts to flow. Then, the process proceeds from step S67 to step S68, and the upper arm (Q1) of boost converter 12A is controlled to be on.

Thereafter, the battery BA also supplies power to the load.
If there is no upper arm ON request in step S51, or if the process of step S58 or S68 ends, the process proceeds to step S69, and control is transferred to the main routine.

  Here, referring to FIG. 1 again, the operation in the third embodiment will be described. In the third embodiment, two DC power supplies out of the plurality of DC power supplies are batteries BA and BB1, which are first and second power storage devices. As shown in FIG. 9, each of voltage conversion units 39A and 39B corresponding to the first and second power storage devices includes a coil and switching elements Q1A and Q1B provided between common power supply line PL2 and the coil. And rectifying elements D1A and D1B provided in parallel to the switching elements, and current sensors 100A and 100B for detecting a current flowing through the coil. The control device 30 controls the switching element (Q1A in FIG. 9) corresponding to the one of the batteries BA and BB1 having the higher power supply voltage to be in a conductive state, and the switching element (Q1A in FIG. 9) In FIG. 9, Q1B) is controlled to be in a non-conducting state, and when a current is detected by the current sensor (100B in FIG. 9) of the other voltage converter, the difference between the power supply voltages of the first and second power storage devices is predetermined. Judged to be below the value.

  In the third embodiment, since the current sensors also detect that the voltages of the two batteries are equal, the voltage detection accuracy is improved.

[Modification]
In the first to third embodiments, an example in which two batteries are used has been introduced. However, the present invention can be applied to a configuration in which the number of batteries is further added and the batteries are used by switching one after another.

  FIG. 10 is a circuit diagram showing a configuration of a vehicle in which a plurality of sub batteries are mounted on the main battery.

  Referring to FIG. 10, vehicle 1A includes, in the configuration of vehicle 1 shown in FIG. 1, a voltage conversion unit 39C instead of voltage conversion unit 39B, and further includes a battery BB2 and a voltage sensor 10B2. Since other vehicle 1A is the same as vehicle 1, description thereof will not be repeated.

  Voltage conversion unit 39C includes a system main relay SR2G that is a connection unit provided on the negative electrode side of battery BB2, and a connection unit 40C, in addition to the configuration of voltage conversion unit 39B shown in FIG. Connection unit 40C includes a system main relay SR2B connected between the positive electrode of battery BB2 and power supply line PL1B, a system main relay SR2P connected in series with system main relay SR2B, and a limiting resistor R2. Including. System main relay SR2G is connected between the negative electrode of battery BB2 and ground line SL2.

  System main relays SR2P, SR2B, and SR2G are controlled to be in a conductive / non-conductive state in accordance with control signals CONT7 to CONT9 provided from control device 30.

  Boost converter 12B is selectively connected to any one of a plurality of sub-batteries BB1 and BB2 to perform voltage conversion.

  One of secondary batteries BB1 and BB2 and main battery BA can output the maximum power allowed for an electrical load (such as inverter 22 and motor generator MG2) connected to the power supply line when used simultaneously, for example. Is set to the chargeable capacity. As a result, traveling at maximum power is possible in EV (Electric Vehicle) traveling without using the engine. If the power storage state of the secondary battery deteriorates, the secondary battery may be replaced and run further. If the power of the secondary battery is consumed, the maximum power can be run without using the secondary battery by using the engine in addition to the main battery.

  Further, with such a configuration, the boost converter 12B is shared by a plurality of sub-batteries, so that the number of boost converters need not be increased by the number of batteries. In order to further extend the EV travel distance, a battery may be added in parallel to the batteries BB1 and BB2.

  Even when the configuration as shown in FIG. 10 is adopted, the present invention can be easily applied by replacing the sub-battery used with the battery BB1 in the flowcharts of FIGS. 4, 7, and 8. Can do.

  In addition, the control methods disclosed in the above embodiments can be executed by software using a computer. A program for causing a computer to execute this control method is read from a recording medium (ROM, CD-ROM, memory card, etc.) recorded in a computer-readable manner into a computer in a vehicle control device or provided through a communication line. You may do it.

  In the present embodiment, an example is shown in which the present invention is applied to a series / parallel type hybrid system in which the power of the engine can be divided and transmitted to the axle and the generator by the power split mechanism. However, the present invention uses an engine only for driving a generator and generates a driving force of an axle only with a motor that uses electric power generated by the generator, an electric vehicle that runs only with a motor, It can also be applied to fuel cell vehicles.

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

1 is a diagram illustrating a main configuration of a vehicle 1 according to an embodiment of the present invention. It is a circuit diagram which shows the detailed structure of the inverters 14 and 22 of FIG. FIG. 2 is a circuit diagram showing a detailed configuration of boost converters 12A and 12B in FIG. 1. It is a flowchart for demonstrating control with respect to voltage conversion part 39A, 39B in Embodiment 1 of this invention. It is a figure for demonstrating the conditions from which pressure | voltage rise is unnecessary with a step-up converter. FIG. 5 is a circuit diagram for illustrating a state of charging performed in step S8 of FIG. It is a flowchart for demonstrating control with respect to voltage conversion part 39A, 39B in Embodiment 2 of this invention. 10 is a flowchart for illustrating control in the third embodiment. FIG. 6 is a circuit diagram for illustrating a current flow in a third embodiment. It is the circuit diagram which showed the structure of the vehicle carrying a some sub battery with respect to the main battery.

Explanation of symbols

  1, 1A vehicle, 2 wheels, 3 power split mechanism, 4 engine, 10A, 10B1, 10B2, 13, 21A, 21B, 74 voltage sensor, 12A, 12B boost converter, 14, 22 inverter, 15 U-phase arm, 16 V Phase arm, 17 W-phase arm, 24, 25, 100A, 100B Current sensor, 30 Control device, 39A, 39B, 39C Voltage converter, 40A, 40B Connection, 50 input terminal, 51 Relay circuit, 90 Commercial power supply, ACL1 , ACL2 power input line, BA, BB1, BB2 battery, C1, C2, CH smoothing capacitor, D1-D8 diode, L1 reactor, MG1, MG2 motor generator, N1, N2 neutral point, PL1A, PL1B, PL2 power line , Q1-Q8 IGBT elements, R0, R1 , R2 limiting resistor, RY1, RY2 relay, SL1, SL2 ground line, SMRP, SMRB, SMRG, SR1P, SR1B, SR1G, SR2P, SR2B, SR2G System main relay.

Claims (12)

A plurality of DC power supplies for supplying power to a motor for driving the wheels;
A plurality of voltage converters connected between the plurality of DC power supplies and a common power supply node to perform voltage conversion;
A control device for controlling the plurality of voltage converters,
Each of the plurality of voltage converters is
A coil whose one end is electrically connected to the positive electrode of the corresponding DC power source;
A switching element connected between the other end of the coil and the common power supply node,
The control device reduces a difference between power supply voltages of the plurality of DC power supplies when the output request from the vehicle load to the vehicle power supply device is reduced and voltage conversion by the plurality of voltage conversion units is not necessary. And a process for simultaneously turning on each of the switching elements of the plurality of voltage converters so that each power supply node of the plurality of DC power supplies is connected to the common power supply node. The first voltage conversion unit among the plurality of voltage conversion units is:
A first boost converter configured to include the coil and the switching element and boost the voltage of a first DC power supply of the plurality of DC power supplies and supply the boosted voltage to the common power supply node;
Including a first connection for connecting the first DC power source and the first boost converter;
The first connection portion is
A first relay and a limiting resistor connected in series disposed between the first DC power source and the first boost converter;
A second relay for directly connecting the first DC power source and the first boost converter;
The control device releases the second relay and keeps the first relay connected until a voltage difference between the first DC power source and another DC power source becomes a predetermined value or less, 2. The vehicle power supply device according to claim 1, wherein the second relay is controlled to be in a connected state after a difference in voltage between the DC power supply of the second DC power supply and another DC power supply becomes a predetermined value or less.   When the output request from the vehicle load to the power supply device of the vehicle is equal to or less than a predetermined value, the control device reduces a difference in power supply voltages of the plurality of DC power supplies, and the power supply device of the vehicle from the vehicle load 2. The vehicle according to claim 1, wherein when the output request for is greater than a predetermined value, the power supply voltage of the corresponding DC power supply is boosted and output to the common power supply node by at least one of the plurality of voltage conversion units. Power supply. Two DC power sources out of the plurality of DC power sources are first and second power storage devices,
Before SL controller by controlling the switching of each switching element of said plurality of voltage conversion units, the first, the other power storage from one of the power storage device such that the voltage difference between the second power storage devices is reduced The vehicle power supply device according to claim 1, wherein power is transferred to the device. Two DC power sources out of the plurality of DC power sources are first and second power storage devices,
Each of the first and second voltage converters corresponding to the first and second power storage devices respectively
A rectifying element provided in parallel before Symbol switching element,
A current sensor for detecting a current flowing through the coil,
The control device controls the switching element of one voltage conversion unit corresponding to the higher power supply voltage of the first and second power storage devices to be in a conductive state, and sets the switching element of the other voltage conversion unit to a non-conductive state. The control is performed in a conductive state, and it is determined that a difference between power supply voltages of the first and second power storage devices is equal to or less than a predetermined value when a current is detected by a current sensor of the other voltage conversion unit. A power supply device for a vehicle according to claim 1. At least one of the plurality of DC power supplies is a power storage device;
The power supply device for a vehicle according to claim 1, further comprising a power receiving unit that receives power from the external power supply in order to charge the power storage device from an external power supply. A power supply for a vehicle comprising a plurality of DC power supplies for supplying power to a motor for driving wheels, and a plurality of voltage conversion sections connected between the plurality of DC power supplies and a common power supply node for performing voltage conversion, respectively. An apparatus control method comprising:
Each of the plurality of voltage converters is
A coil whose one end is electrically connected to the positive electrode of the corresponding DC power source;
A switching element connected between the other end of the coil and the common power supply node,
When the output request from the vehicle load to the power supply device of the vehicle decreases and voltage conversion by the plurality of voltage conversion units becomes unnecessary, the plurality of the plurality of DC power supplies are reduced so as to reduce the difference between the plurality of DC power supplies. A first step of controlling the voltage converter of
When output requests from the vehicle load to the power supply device of the vehicle decrease and voltage conversion by the plurality of voltage conversion units becomes unnecessary , each power supply node of the plurality of DC power supplies is connected to the common power supply node. And a second step of simultaneously turning on each of the switching elements of the plurality of voltage converters. The first voltage conversion unit among the plurality of voltage conversion units is:
A first boost converter configured to include the coil and the switching element and boost the voltage of a first DC power supply of the plurality of DC power supplies and supply the boosted voltage to the common power supply node;
Including a first connection for connecting the first DC power source and the first boost converter;
The first connection portion is
A first relay and a limiting resistor connected in series disposed between the first DC power source and the first boost converter;
A second relay for directly connecting the first DC power source and the first boost converter;
The first step includes
Maintaining the released state of the second relay until a voltage difference between the first DC power source and another DC power source becomes equal to or less than the predetermined value;
Maintaining the connected state of the first relay until the voltage difference between the first DC power source and the other DC power source is equal to or less than the predetermined value,
The second step includes
The vehicle power supply device according to claim 7, further comprising a step of controlling the second relay to be in a connected state after a voltage difference between the first DC power supply and another DC power supply becomes equal to or less than the predetermined value. Control method. The control method is:
Further comprising the step of determining whether an output request from the vehicle load to the power supply device of the vehicle is a threshold value or less;
The method of controlling a power supply device for a vehicle according to claim 7, wherein the first step is executed when the output request is equal to or less than the threshold value. Two DC power sources out of the plurality of DC power sources are first and second power storage devices,
Before SL first step, by controlling the switching of each switching element of said plurality of voltage conversion units, the first, one from the other power storage device such that the voltage difference between the second power storage devices is reduced The method for controlling a power supply device for a vehicle according to claim 7, wherein electric power is transferred to the power storage device. Two DC power sources out of the plurality of DC power sources are first and second power storage devices,
Each of the first and second voltage converters corresponding to the first and second power storage devices respectively
A rectifying element provided in parallel before Symbol switching element,
A current sensor for detecting a current flowing through the coil,
The first step includes
Controlling the switching element of one of the voltage conversion units corresponding to the higher power supply voltage of the first and second power storage devices to a conductive state;
Controlling the switching element of the other voltage converter to a non-conductive state;
And determining that a difference between power supply voltages of the first and second power storage devices is equal to or less than a predetermined value when a current is detected by a current sensor of the other voltage conversion unit. Method for controlling the power supply device of the vehicle. At least one of the plurality of DC power supplies is a power storage device;
The power supply device of the vehicle is
The vehicle power supply device control method according to claim 7, further comprising a power receiving unit that receives electric power from the external power supply in order to charge the power storage device from an external power supply.

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