JP2012152003A - Power supply device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for vehicle, capable of implementing charging without generating an overcurrent when battery depletion occurs.SOLUTION: The power supply device for vehicle includes: a high-voltage battery 11; an auxiliary battery 12 with an output voltage lower than the high-voltage battery 11; a control power node with a connection terminal 25 connectable with an external power supply 30; a DC-DC converter 22 that receives a control power voltage VCC from the control power node, receives an output of the high-voltage battery 11 for voltage conversion and charges the auxiliary battery 12; and a switch circuit that can switch electrical connection between the control power node and the auxiliary battery 12.

Description

  The present invention relates to a vehicle power supply device, and more particularly to a vehicle power supply device capable of supplying power from a high voltage battery to an auxiliary battery.

  2. Description of the Related Art In recent years, attention has been focused on vehicles that are equipped with a power supply device and drive a vehicle driving motor with the electric power, such as electric vehicles, hybrid vehicles, and fuel cell vehicles, as vehicles that take vehicles into consideration.

  Japanese Patent Laying-Open No. 2009-131077 (Patent Document 1) discloses a power supply device for a vehicle configured to be able to charge a power storage device from the outside of the vehicle. In this vehicle, electric power supplied from an external power source is supplied to an auxiliary battery via a DC / DC converter.

JP 2009-131077 A JP 2002-209301 A

  The configuration disclosed in Japanese Patent Laid-Open No. 2009-131077 can surely charge the auxiliary battery from the external power source via the DC / DC converter. However, a configuration in which power from the auxiliary battery is used for controlling the DC / DC converter is also assumed. In such a configuration, once the auxiliary battery has run out of battery, the DC / DC converter cannot be activated even if it is connected to an external power source, and eventually the auxiliary battery cannot be charged. There is a fear.

  In such a case, an external power source such as another vehicle or a DC charger has been connected to the connecting terminal for charging the auxiliary battery by using a booster cable or the like for relief.

  Currently, many hybrid vehicles and electric vehicles use nickel-metal hydride batteries or lithium batteries as high-voltage batteries, which are power sources for vehicle drive motors, and lead batteries as auxiliary batteries.

  However, it is conceivable that nickel hydride batteries and lithium batteries used for high voltage batteries will be used for auxiliary batteries in the future. In particular, when a nickel metal hydride battery, a lithium battery, or the like is composed of a large number of battery cells, it is also conceivable to use some of the cells as an auxiliary battery that outputs a low voltage.

  Since the lead battery has a large internal resistance, when the lead battery is used as an auxiliary battery, even if an external power source is connected to the auxiliary battery, the charging current is limited to some extent. However, nickel-metal hydride batteries and lithium batteries have lower internal resistance than lead batteries, so if you try to charge them directly by connecting to an external power source like lead batteries, overcurrent flows through the auxiliary battery and charging cable. There is a risk that. For this reason, it is necessary to perform charge control when charging the auxiliary machine battery when it occurs.

  An object of the present invention is to provide a power supply device for a vehicle that can be charged without generating an overcurrent when a battery runs out.

  In summary, the present invention is a power supply device for a vehicle, which is a control power supply node capable of connecting an external power supply to a first power storage device, a second power storage device whose output voltage is lower than that of the first power storage device. A voltage converter capable of receiving a control power supply voltage from the control power supply node, receiving the output of the first power storage device, performing voltage conversion and charging the second power storage device, and a control power supply node And a switch circuit capable of switching electrical connection between the power storage device and the second power storage device.

  Preferably, when an external power supply is connected to the control power supply node, the switch circuit includes the control power supply node and the second power storage device so that no current flows from the control power supply node to the second power storage device. Disconnect the electrical connection between.

  Preferably, the vehicle includes a vehicle drive unit that receives supply of electric power from the first power storage device. The switch circuit includes a relay provided between the control power supply node and the second power storage device. The vehicle power supply device is operable when a power supply voltage is supplied from one of the second power storage device and the control power supply node, and further includes a control device that controls the switch circuit. The control device controls the relay to be in a conductive state when the vehicle is driven so that the vehicle drive unit can be driven, and controls the relay to a non-conductive state when an external power source is connected to the control power supply node.

  More preferably, the vehicle power supply device further includes a power management unit that monitors the current of the second power storage device and controls the voltage converter. When it is detected that the current of the second power storage device is an overcurrent, the power management unit controls the voltage converter so that the second power storage device is not charged from the voltage converter, Thereafter, when it is continuously detected that the current of the second power storage device is an overcurrent, the switch circuit disconnects the electrical connection between the control power supply node and the second power storage device.

  More preferably, when it is detected that the current of the second power storage device is an overcurrent, the power management unit controls the voltage of the voltage converter to be equal to or lower than the voltage of the second power storage device. The second power storage device is prevented from being charged from the converter.

  According to the present invention, even when the battery runs out, the vehicle can be started by applying the power supply voltage from the outside of the vehicle without causing an overcurrent.

It is a figure for demonstrating schematic structure of the vehicle with which the power supply device of embodiment of this invention is applied. It is a figure for demonstrating the structure of the battery pack 10 of FIG. It is the block diagram which showed schematic structure of the power supply device of a vehicle. 5 is a flowchart for illustrating normal starting control of vehicle 100. 4 is a flowchart for illustrating control when the system of vehicle 100 is shut down. It is a flowchart for demonstrating control of charge of the auxiliary machine battery at the time of battery exhaustion. FIG. 5 is a block diagram showing a configuration of a vehicle 100A according to a second embodiment. 10 is a flowchart for illustrating charge control when the battery is exhausted, executed in the second embodiment.

  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.

[Embodiment 1]
FIG. 1 is a diagram for explaining a schematic configuration of a vehicle to which a power supply device according to an embodiment of the present invention is applied.

  Referring to FIG. 1, vehicle 100 includes a battery pack 10 mounted at the rear of the vehicle and a vehicle drive unit 21 mounted at the front of the vehicle. The vehicle drive unit 21 includes a vehicle drive motor, an inverter for driving the motor, and the like. In the case of a hybrid vehicle, the vehicle drive unit 21 further includes an engine.

  A DC / DC converter 22 is provided in the vicinity of the motor drive inverter. A relay box 23 for connecting the external power source (or car) 30 to the booster cable 32 is also provided at the front of the vehicle in preparation for when the battery runs out. The vehicle drive unit 21 and the battery pack 10 behind the vehicle are connected in the vehicle by a power cable 28.

FIG. 2 is a diagram for explaining the configuration of the battery pack 10 of FIG.
Referring to FIG. 2, battery pack 10 includes a high voltage battery 11 and an auxiliary battery 12. A system main relay SMR is connected to the high voltage battery. The high voltage battery 11 is connected to the power cable 28 via the system main relay SMR.

  The auxiliary battery 12 is a low voltage battery for driving auxiliary machines such as various ECUs, audio devices, and power windows of the vehicle. The power supply voltage of the high voltage battery 11 is 200V, for example, and the power supply voltage of the auxiliary battery 12 is 12V, for example. However, the high voltage battery 11 and the auxiliary battery 12 are both lithium ion batteries or nickel metal hydride batteries, and are integrated in the battery pack 10.

FIG. 3 is a block diagram showing a schematic configuration of a power supply device for a vehicle.
Referring to FIG. 3, vehicle 100 includes a high voltage battery 11, a system main relay SMR, a vehicle drive unit 21, a DC / DC converter 22, an auxiliary battery 12, a relay box 23, a power supply ECU (Electronic). Control Unit) 24, power management unit 40, and start switch 27.

  The high voltage battery 11 is connected to the DC / DC converter 22 and the vehicle drive unit 21 by the power cable 28 in FIG. 1 through the system main relay SMR. Vehicle drive unit 21 includes a vehicle drive motor, a motor drive inverter, and the like when vehicle 100 is an electric vehicle, and further includes an engine and the like when vehicle 100 is a hybrid vehicle.

  DC / DC converter 22 charges auxiliary battery 12 by reducing the voltage of high voltage battery 11 to a low voltage (for example, 12 to 14 V). The auxiliary battery 12 supplies a power supply voltage to an auxiliary machine (not shown) (for example, an audio device or a power window).

  Relay box 23 includes a relay IGCT and a terminal 25. The terminal 25 is a terminal for connecting the external power supply 30 for relief with the booster cable 32 when the auxiliary battery 12 has run out of battery. The terminal 25 is provided in a control power supply node that supplies a control power supply voltage to the power management unit and the DC / DC converter 22. A clip or the like for connecting to the terminal 25 is provided at the tip 26 of the booster cable 32.

  When the auxiliary battery 12 has not run out of battery, when the user presses the start switch 27, the power supply ECU 24 turns on the relay IGCT, thereby causing the power management unit 40 and the DC / DC converter to have a control power supply voltage. VCC is supplied. As a result, the power management unit 40 and the DC / DC converter 22 are activated. The power management unit 40 supplies the power supply voltage of the high voltage battery 11 between the terminals P and N of the DC / DC converter 22 by turning on the system main relay SMR. Although not shown, the DC / DC converter 22 steps down the voltage once converted into alternating current by the switching element with a transformer or the like, further rectifies the reduced alternating voltage into direct current, and charges the auxiliary battery 12 with a charging voltage. Supply. The DC / DC converter 22 also supplies power to an auxiliary load (headlamp, power window, audio device, etc.) connected to the auxiliary battery 12.

  Here, when the auxiliary battery 12 has risen, if the terminal 25 for connecting the external power source 30 for rescue is provided at a node directly connected to the positive electrode of the auxiliary battery, the auxiliary battery 12 An excessive current may flow through the.

  For this reason, in the vehicle 100, the connection terminal 25 is provided in a portion where power can be supplied to the DC / DC converter 22, the power supply ECU 24, and the power management unit 40. At this time, the voltage from the external power source 30 is not directly applied to the auxiliary battery 12 by keeping the relay IGCT in a non-conductive state. When the auxiliary battery 12 has risen, the DC / DC converter 22 and the power management unit 40 are activated by connecting the external power supply 30 to the terminal 25. The power management unit 40 uses the DC / DC converter 22 to charge the auxiliary battery 12 with the electric power of the high voltage battery 11. Then, in response to the disconnection of the external power supply 30 from the terminal 25, the power management unit 40 turns off the system main relay SMR and enters a standby state waiting for activation by the start switch 27. In response to the driver pressing the start switch 27, the vehicle 100 is restarted according to a normal sequence.

FIG. 4 is a flowchart for illustrating normal starting control of vehicle 100.
With reference to FIGS. 3 and 4, when the start switch 27 is first pressed, the processing of this flowchart is started. In step S1, the power supply ECU 24 controls the relay IGCT to be turned on. As a result, the power supply voltage VCC for the control circuit is supplied from the auxiliary battery 12 to the power management unit 40 and the DC / DC converter 22. In response to this, the power management unit 40 turns on the system main relay SMR in step S2. As a result, the power supply voltage from the high voltage battery 11 is supplied to the vehicle drive unit 21 in step S3. In step S4, the vehicle is in a ReadyON state where it can start.

  FIG. 5 is a flowchart for illustrating control when the system of vehicle 100 is shut down.

  Referring to FIGS. 3 and 5, when start switch 27 is set to the off state, the process is started, and vehicle drive unit 21 is controlled to the off state in step S11. Then, after the system main relay SMR is turned off by the power management unit 40 in step S12, the process proceeds to step S13. In step S13, the power supply ECU 24 turns off the relay IGCT, and then the process ends in step S14.

  FIG. 6 is a flowchart for illustrating control of charging of the auxiliary battery when the battery is exhausted. The process of this flowchart is started when the external power supply 30 is connected to the terminal 25 when the auxiliary battery 12 is in a battery exhausted state.

  3 and 6, control power supply voltage VCC is supplied from external power supply 30 to DC / DC converter 22 and power management unit 40 in step S21. In response, power management unit 40 turns on system main relay SMR in step S22.

  In the subsequent step S23, the DC / DC converter 22 starts operating, and a voltage for charging the auxiliary battery 12 using the electric power of the high voltage battery 11 is generated. In step S24, the auxiliary battery 12 is charged.

  In step S25, the power management unit 40 and the power supply ECU 24 determine whether or not the connection of the external power supply 30 is continued. If the connection of the external power supply is continued in step S25, the process proceeds to step S26, and power supply ECU 24 continues to control relay IGCT to the off state. When the process of step S26 ends, the process of step S24 is executed again.

  On the other hand, when the connection of the external power supply 30 is not detected in step S25, the process proceeds to step S27, the charging of the auxiliary battery 12 is terminated by stopping the DC / DC converter 22, and the power management unit 40 is stopped. As a result, the system main relay SMR is set to the off state. In step S28, the power supply ECU 24 enters a standby state waiting for the start switch 27 to be set to ON. When the start switch 27 is set to the on state in step S28, the process proceeds to step S29, and the vehicle is set to the ready ON state according to the procedure described in the flowchart of FIG.

  As described above, in the first embodiment, the external power supply 30 is used to supply the control power supply voltage VCC to the DC / DC converter 22 and the power management unit 40, and is used for the auxiliary battery 12. It does not supply power directly. The auxiliary battery 12 is supplied with power from the high voltage battery 11 via the DC / DC converter 22. At this time, since the DC / DC converter 22 is controlled by the power management unit 40 so as not to generate an overcurrent, the auxiliary battery 12, compared with the case where the auxiliary battery 12 is directly charged from the external power source 30. No overcurrent is generated in the external power supply 30 and the booster cable 32.

  In the first embodiment, the auxiliary battery is described as an example of a battery having a low internal resistance, such as a nickel metal hydride battery. However, the present invention is not limited to this. Even when a conventional lead battery is used as an auxiliary battery, if the configuration of the present embodiment is adopted, the external power supply for relief only supplies the control power supply voltage, and the charging current is supplied from the high voltage battery. Therefore, for example, there is an advantage that the booster cable may be thin, and an advantage that a smaller battery may be used as an external power source for relief.

[Embodiment 2]
FIG. 7 is a block diagram showing a configuration of vehicle 100A of the second embodiment.

  A vehicle 100A in FIG. 7 basically has the same configuration as that of vehicle 100 shown in FIG. The vehicle 100 </ b> A includes a power management unit 40 </ b> A instead of the power management unit 40. In the case of vehicle 100 in the first embodiment, charging of auxiliary battery 12 can be started by simply connecting external power supply 30 to terminal 25 of relay box 23 without pressing start switch 27. However, after the external power supply 30 is once connected to the terminal 25 by the user and the relay IGCT is turned on by the power supply ECU 24, the external power supply 30 is once disconnected from the terminal 25, and then the external power supply 30 is connected to the terminal 25 again. In such a case, an overcurrent may occur in the auxiliary battery 12.

  7 monitors the current and voltage of the auxiliary battery 12. Then, according to the monitoring result, the power management unit 40A gives an output voltage command to the DC / DC converter 22.

  The power management unit 40A that senses that an overcurrent has flowed through the auxiliary battery 12 instructs the DC / DC converter 22 to lower the output voltage. Instead of outputting a command to lower the output voltage to the DC / DC converter 22, the operation of the DC / DC converter 22 may be temporarily stopped.

  If the overcurrent continues to flow through the auxiliary battery 12 even if the output voltage of the DC / DC converter is lower than the power supply voltage of the normal auxiliary battery 12, the power management unit 40A causes the external power supply 30 to be connected to the terminal 25. It is determined that the power supply ECU 24 has been reconnected, and relay IGCT is turned off.

  In addition, when the user does not operate the start switch 27 after the external power supply 30 is disconnected from the terminal 25 and the predetermined time has elapsed, the power management unit 40A turns off the system main relay SMR and sets the vehicle in the ReadyOFF state. To do.

  FIG. 8 is a flowchart for illustrating charge control when the battery is exhausted, which is executed in the second embodiment. Since normal vehicle startup and shutdown processing is the same as that described with reference to FIGS. 4 and 5, the description thereof will not be repeated here.

  With reference to FIGS. 7 and 8, the processing of this flowchart is started in response to the connection of the external power supply 30 to the terminal 25 when the auxiliary battery 12 has risen. About step S21-step S26, since the process similar to the case demonstrated in FIG. 6 is performed, description is not repeated here.

  In step S25, when the power management unit 40A detects that the external power supply 30 is disconnected, the process proceeds to step S31, and the relay IGCT is made conductive to the power supply ECU 24.

  Accordingly, as shown in step S32, vehicle 100A is set in a ReadyON state where it can start.

  Subsequently, in step S33, it is determined whether or not a state in which the vehicle has not been operated for a certain period of time has elapsed. If it is determined in step S33 that the vehicle has not been operated for a fixed time, the process proceeds to step S34, and the vehicle is controlled to the ReadyOFF state. At this time, the power management unit 40A controls the system main relay SMR to the off state.

  On the other hand, if it is determined in step S33 that the predetermined time has not yet elapsed since the ReadyON state in step S32, the processing in step S35 is performed. In step S35, the power management unit 40A determines whether or not an overcurrent is generated in the auxiliary battery 12 based on the output of the current sensor provided in the auxiliary battery. If no overcurrent has occurred in auxiliary battery 12 in step S35, the process in step S33 is performed again. On the other hand, if an overcurrent has occurred in auxiliary battery 12 in step S35, the process proceeds to step S36.

  In step S <b> 36, the power management unit 40 </ b> A causes the output voltage of the DC / DC converter 22 to be lowered by changing the voltage command given to the DC / DC converter 22. At this time, the voltage command of the DC / DC converter 22 is set to a value lower than the power supply voltage of the auxiliary battery 12. As a result, the auxiliary battery 12 is no longer charged, so the overcurrent state of the auxiliary battery 12 should be eliminated.

  However, if an overcurrent occurs due to the connection of the external power supply 30 to the terminal 25 while the relay IGCT is in a conducting state, the auxiliary battery 12 is not connected to the external battery 12 even if the output voltage of the DC / DC converter 22 is lowered. Since the current from the power supply 30 flows and charging is performed, the overcurrent of the auxiliary battery 12 is not eliminated.

  If the overcurrent state of the auxiliary battery continues in step S37, the process proceeds to step S38. In step S <b> 38, the power management unit 40 </ b> A determines that the external power supply 30 has been reconnected to the terminal 25. Then, the process proceeds to step S39, and the power management unit 40A controls the relay IGCT to be turned off by sending a command to the power supply ECU 24. When the process of step S39 ends, the process from step S25 is executed again. At this time, if the connection of the external power supply 30 is continued, the charging to the auxiliary battery 12 is resumed by repeatedly executing steps S26 and S24.

  On the other hand, when the overcurrent of the auxiliary battery 12 does not continue in step S37, the process proceeds to step S40. In this case, when a normal output voltage is applied from the DC / DC converter 22 to the auxiliary battery 12, an overcurrent has flowed. Therefore, in step S40, the overcurrent from the output of the DC / DC converter 22 is not. It is determined that In step S41, the DC / DC converter 22 is stopped.

  As described above, vehicle 100A according to the second embodiment has external power supply 30 connected to terminal 25 even when external power supply 30 is removed from terminal 25 for some reason while auxiliary battery 12 is being charged. The charging of the auxiliary battery 12 can be resumed simply by reconnecting to 25, which is convenient for the user. That is, unlike the case of the first embodiment, since the loop for waiting for the start switch 27 to be pressed is not entered, the user does not need to restart charging after pressing the start switch.

  Finally, referring to FIG. 1 again, the first and second embodiments of the present application will be summarized. As shown in FIGS. 3 and 7, the vehicle power supply device is provided with a high voltage battery 11, an auxiliary battery 12 whose output voltage is lower than that of the high voltage battery 11, and a connection terminal 25 that can connect an external power supply 30. A control power supply node; a DC / DC converter 22 capable of receiving the control power supply voltage VCC from the control power supply node, receiving the output of the high voltage battery 11 and performing voltage conversion to charge the auxiliary battery 12; A switch circuit capable of switching electrical connection between the control power supply node and the auxiliary battery.

  Preferably, when the external power supply 30 is connected to the control power supply node, the switch circuit includes the control power supply node and the auxiliary battery 12 so that no current flows from the control power supply node to the auxiliary battery 12. Disconnect the electrical connection between.

  The electrical connection may be disconnected by opening a circuit like a relay or by preventing a current from flowing through a semiconductor such as a diode or a transistor.

  Preferably, the vehicle includes a vehicle drive unit 21 that receives supply of electric power from the high-voltage battery 11. The switch circuit includes a relay IGCT provided between the control power supply node and auxiliary battery 12. The vehicle power supply device is operable when a power supply voltage is supplied from any one of the auxiliary battery 12 and the control power supply node, and further includes a control device that controls the switch circuit. The control device controls the relay IGCT to be in a conductive state when the vehicle driving unit 21 can be driven, and controls the relay IGCT to be in a non-conductive state when the external power supply 30 is connected to the control power supply node. .

  Instead of relay IGCT, a diode may be connected so that the direction from auxiliary battery 12 toward terminal 25 is the forward direction.

  More preferably, as described with reference to FIGS. 7 and 8, the vehicle power supply apparatus further includes a power management unit 40 that monitors the current of the auxiliary battery 12 and controls the DC / DC converter 22. When it is detected that the current of the auxiliary battery 12 is an overcurrent, the power management unit 40 sets the DC / DC converter 22 so that the auxiliary battery 12 is not charged from the DC / DC converter 22. Then, when it is detected that the current of the auxiliary battery 12 is overcurrent after that, the switch circuit disconnects the electrical connection between the control power supply node and the auxiliary battery 12.

  More preferably, as shown in step S36 of FIG. 8, when it is detected that the current of the auxiliary battery 12 is an overcurrent, the power management unit 40 supplies the voltage of the DC / DC converter 22 to the auxiliary machine. The auxiliary battery 12 is prevented from being charged from the DC / DC converter 22 by controlling the voltage below the voltage of the battery 12.

  The auxiliary battery 12 may not be charged from the DC / DC converter 22 by stopping the operation of the DC / DC converter 22.

  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.

  DESCRIPTION OF SYMBOLS 10 Battery pack, 11 High voltage battery, 12 Auxiliary battery, 21 Vehicle drive part, 22 DC / DC converter, 23 Relay box, 24 Power supply ECU, 25 Terminal, 27 Start switch, 28 Power cable, 30 External power supply, 32 Booster cable , 40, 40A Power management unit, 100, 100A vehicle, IGCT relay, SMR system main relay.

Claims (5)

A first power storage device;
A second power storage device having an output voltage lower than that of the first power storage device;
A control power node to which an external power supply can be connected;
A voltage converter that receives a control power supply voltage from the control power supply node, receives the output of the first power storage device, performs voltage conversion, and charges the second power storage device;
A vehicle power supply device comprising: a switch circuit capable of switching electrical connection between the control power supply node and the second power storage device.   When the external power supply is connected to the control power supply node, the switch circuit includes the control power supply node and the second power supply node so that no current flows from the control power supply node to the second power storage device. The power supply device for a vehicle according to claim 1, wherein electrical connection between the two power storage devices is disconnected. The vehicle is
A vehicle drive unit that receives supply of electric power from the first power storage device;
The switch circuit is
Including a relay provided between the control power supply node and the second power storage device;
The power supply device of the vehicle is
A power supply voltage is supplied from one of the second power storage device and the control power supply node;
The control device controls the relay to be in a conductive state when the vehicle is driven so that the vehicle drive unit can be driven, and puts the relay in a non-conductive state when the external power source is connected to the control power supply node. The power supply device for a vehicle according to claim 1 or 2, which is controlled. The power supply device of the vehicle is
A power management unit that monitors the current of the second power storage device and controls the voltage converter;
When the power management unit detects that the current of the second power storage device is an overcurrent, the voltage conversion unit prevents the second power storage device from being charged from the voltage converter. And when the current of the second power storage device continues to be detected as an overcurrent, the switch circuit is connected to the electric power between the control power supply node and the second power storage device. The power supply device for a vehicle according to claim 2, wherein the power connection is disconnected.   When it is detected that the current of the second power storage device is an overcurrent, the power management unit controls the voltage of the voltage converter to be equal to or lower than the voltage of the second power storage device. The power supply device for a vehicle according to claim 4, wherein charging is not performed from the voltage converter to the second power storage device.

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