JP2019047554A - Power supply system for vehicle - Google Patents

Abstract

To provide a power supply system for vehicle capable of operating an inverter circuit which drives a traveling motor of a vehicle, efficiently at all the time.SOLUTION: A power supply system 1 for vehicle comprises a battery 10, a capacitor 20, a DC power converter 30, a switch device 50 and a control device 60. The battery 10 and the capacitor 20 are connected via the DC power converter 30. The DC power converter 30 is a bidirectional insulated power converter. The control device 60 controls a conversion mode and an output voltage of the DC power converter 30 and an ON/OFF state of the switch device 50. The ON/OFF state of the switch device 50 is set to a predetermined state to be able to set a state where the battery 10 and the DC power converter 30 are connected in parallel, a state where an inverter circuit IV and the DC power converter 30 are connected in parallel or a state where the battery 10 and the DC power converter 30 are connected in series and a circuit formed by connecting the battery 10 and the DC power converter 30 in series is connected in parallel to the inverter circuit IV.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply system for a vehicle.

  For example, Patent Document 1 below describes a vehicle power supply system that supplies power to an inverter circuit that drives a traveling motor of a vehicle. The vehicle power supply system includes a battery (chemical battery (for example, lithium ion battery)) as a main power supply and a capacitor (for example, a physical battery (for example, an electric double layer capacitor)) as an auxiliary power supply. In Patent Document 1, a battery and a capacitor are connected in parallel via a DC power converter. The DC power converter boosts the output voltage of the capacitor to be equal to the output voltage of the battery. Thus, battery power and capacitor power can be simultaneously supplied to the inverter circuit.

  Further, for example, the following Patent Document 2 also describes a vehicle power supply system including a battery as a main power supply and a capacitor as an auxiliary power supply. In Patent Document 2, when the storage amount of the capacitor is sufficient, the battery and the capacitor are directly connected in series. Then, power is supplied to the inverter circuit from the power storage device formed by connecting the battery and the capacitor in series.

JP, 2011-66972, A JP 2014-226010 A

  Generally, when a predetermined voltage (rated power supply voltage) is applied to the power supply terminal of the inverter circuit, the traveling motor can be driven most efficiently. Also, in general, in the battery, the output voltage (voltage between terminals) gradually decreases with the passage of discharge time, but the change width is relatively small (see FIG. 2). On the other hand, the change width of the output voltage (voltage between terminals) of the capacitor with respect to the discharge time is relatively large (see FIG. 3).

  In Patent Document 1, the output voltage of the capacitor is boosted equal to the output voltage of the battery. Therefore, the reduction in the output voltage of the battery (the portion with the halftone dots in FIG. 2) can not be compensated using the power of the capacitor. That is, in the configuration of Patent Document 1, the power supply voltage of the inverter circuit can not be maintained at the predetermined value. Therefore, it is not possible to drive the traveling motor of the vehicle efficiently.

  On the other hand, in Patent Document 2, since the battery and the capacitor are connected in series, a voltage obtained by adding the output voltage of the battery and the output voltage of the capacitor is applied to the power supply terminal of the inverter circuit. However, in the configuration of Patent Document 2, as the power of the battery and the capacitor is consumed by the inverter circuit, the output voltage of the battery and the capacitor decreases. In particular, the output voltage of the capacitor is greatly reduced. As described above, in the configuration of Patent Document 2, the power supply voltage of the inverter circuit can not be maintained at the predetermined value. Therefore, it is not possible to drive the traveling motor of the vehicle efficiently.

  The present invention has been made to address the above-mentioned problems, and an object thereof is to provide a power supply system for a vehicle capable of efficiently driving a traveling motor of the vehicle. In the following description of each component of the present invention, the reference numerals of corresponding parts of the embodiment are described in parentheses in order to facilitate understanding of the present invention, but each component of the present invention is It should not be construed as limited to the configuration of the corresponding portion indicated by the reference numerals of the embodiment.

In order to achieve the above object, the features of the present invention include an inverter circuit (IV) having a function of driving a traveling motor (MT) of a vehicle and a function of outputting regenerative power, and an accessory (AC) of the vehicle Power storage device (10) and second power storage device (20) for storing power supplied to the first power storage device, a first input / output unit (31) connected to the first power storage device and the inverter circuit, and the second power storage device The device and the second input / output unit (32) connected to the auxiliary device, and changing the voltage of the DC power supplied to one of the input / output units according to the setting signal (CS ₃₀ ) for setting the output voltage value And a plurality of switches (51) for switching the connection of the first input / output unit, the first power storage device, and the inverter circuit. , 52, 53), In accordance with the voltage of the power input to the counter isolated power converter _{(V 10, V 20, V} IV), with generating and outputting the setting signal, the plurality of switches on and off states respectively predetermined Setting the first power storage device and the first input / output unit in parallel, setting the inverter circuit and the first input / output unit in parallel, or A circuit formed by connecting a power storage device and the first input / output unit in series and connecting the first power storage device and the first input / output unit in series is connected in parallel to the inverter circuit And a control device (60) for the vehicle power supply system (1). The bidirectional insulation type DC power converter is an operation mode in which DC power obtained by converting a voltage of DC power supplied to the first input / output unit according to a setting signal is output from the second input / output unit, and An operation mode for outputting, from the first input / output unit, DC power obtained by converting a voltage of the DC power supplied to the second input / output unit according to a setting signal, and a circuit on the first input / output unit side and the second It means a device in which the circuit on the input / output side is electrically isolated.

  In this case, the first power storage device is a device that converts electrical energy into chemical energy and stores it, converts the stored chemical energy into electrical energy and releases it, and the second power storage device It is preferable that the device be a device that stores electrical energy as it is and discharges the stored electrical energy as it is. The second power storage device preferably has a smaller internal resistance than the first power storage device, and is a device with less deterioration due to repeated charging and discharging.

  In this case, the second power storage device may be a capacitor.

  In general, the power supply voltage of an inverter circuit for driving a traveling motor of a vehicle is different from the power supply voltage of an accessory. The first power storage device of the power supply system for a vehicle according to the present invention can be mainly used as a power source of the inverter circuit, and the second power storage device can be mainly used as a power source of an accessory.

  Further, in the vehicle power supply system according to the present invention, when the first power storage device and the inverter circuit are set in parallel, the first power storage device is generated using the regenerative power output from the inverter circuit. It can be charged. That is, the regenerative power can be recovered to the first power storage device. In this case, the bidirectional isolated DC power converter may be stopped.

  Further, in the vehicle power supply system according to the present invention, the second power storage device can be charged as follows. First, the first power storage device and the first input / output unit are set in parallel. Then, the power of the first power storage device is supplied to the first input / output unit, and the voltage is converted to the same voltage as the power supply voltage of the accessory and output from the second input / output unit. Thus, the second power storage device can be charged with the same voltage as the power supply voltage of the accessory. In addition, the second power storage device can also be charged as follows. First, the inverter circuit and the first input / output unit are set in parallel. Next, the regenerative power output from the inverter circuit is supplied to the first input / output unit of the power of the first power storage device, and the voltage is converted to the same voltage as the power supply voltage of the accessory to be supplied from the second input / output unit. Output. Also by this, it is possible to charge the second power storage device with the same voltage as the power supply voltage of the accessory.

  Also, the inverter circuit can be driven as follows. First, a circuit formed by connecting the first power storage device and the first input / output unit in series and further connecting the first power storage device and the first input / output unit in series is used as an inverter circuit. Set in parallel connection. Then, the power of the second power storage device is supplied to the second input / output unit, and the voltage is converted as follows and output from the first input / output unit. Specifically, the voltage of the power input to the second input / output unit is set so that the sum of the output voltage of the first power storage device and the output voltage of the first input / output unit is equal to the rated power supply voltage of the inverter circuit. Convert. Thus, the power supply voltage of the inverter circuit can be maintained at the rated power supply voltage. Therefore, according to the present invention, the traveling motor of the vehicle can always be driven efficiently.

  Further, another feature of the present invention is that in the control device, the first power storage device is the first input / output unit and the inverter circuit in a state where the inverter circuit and the first input / output unit are connected in parallel. It is set as the power supply system for vehicles set to the state separated from.

  According to the present invention, the second power storage device can be charged preferentially using the regenerative power output from the inverter circuit. According to this, the deterioration of the first power storage device can be suppressed. Here, in general, a capacitor (physical battery (for example, an electric double layer capacitor)) is less likely to deteriorate than a battery (for example, a chemical battery (for example, lithium ion battery)). Therefore, for example, when a lithium ion battery is adopted as the first storage battery and an electric double layer capacitor is adopted as the second power storage device, the lithium ion battery is charged if the electric double layer capacitor is preferentially charged using regenerative electric power. The number of charge and discharge cycles can be reduced, and deterioration of the lithium ion battery can be suppressed.

It is a circuit diagram of a power supply system for vehicles concerning the present invention. It is a graph which shows an example of the output voltage characteristic of a battery. It is a graph which shows an example of the output voltage characteristic of a capacitor. FIG. 6 is a circuit diagram showing the on / off state of the switch device and the power supply path at the time of start-up. FIG. 7 is a circuit diagram showing the on / off state of the switch device and the power supply path during rotational driving. FIG. 6 is a circuit diagram showing an on / off state of a switch device and a power supply path when charging a capacitor using regenerative power. FIG. 6 is a circuit diagram showing an on / off state of a switch device and a power supply path when charging a battery using regenerative power. It is a flowchart of a starting program. It is a flowchart of a discharge program. It is a flowchart of a charge program.

  A vehicle power supply system 1 according to an embodiment of the present invention will be described. First, an outline of a vehicle to which the vehicle power supply system 1 is applied will be described. The vehicle power supply system 1 is connected to a propulsion device DD and an accessory AC of a vehicle (electric vehicle or hybrid vehicle) as shown in FIG. The vehicle power supply system 1 supplies DC power to the propulsion device DD and the accessory AC. The propulsion device DD includes a traveling motor MT and an inverter circuit IV. The traveling motor MT is a three-phase alternating current motor. The inverter circuit IV converts DC power supplied from the vehicle power supply system 1 into three-phase AC power (U-phase, V-phase and W-phase), and supplies it to the traveling motor MT. The rated power supply voltage of the inverter circuit IV is, for example, 200V. Further, the inverter circuit IV supplies the regenerative power during braking of the vehicle to the vehicle power supply system 1. Vehicle power supply system 1 stores regenerative power supplied from inverter circuit IV. The accessory AC includes an air conditioner, an audio device, a lighting device, and the like. The power supply voltage of the accessory AC is, for example, 15V.

  Below, the structure of the power supply system 1 for vehicles is demonstrated. The vehicle power supply system 1 includes a battery 10, a capacitor 20, a DC power converter 30, a DC power converter 40, a switch device 50, and a control device 60.

The battery 10 is a chargeable / dischargeable battery (chemical battery) using an electrochemical reaction. That is, the battery 10 converts electrical energy into chemical energy and stores it during charging, and converts chemical energy into electrical energy and discharging it when discharging. For example, a lithium ion battery is used as the battery 10. The capacity of the battery 10 is, for example, 6.5 Ah. The rated output voltage of the battery 10 is, for example, 200V. As illustrated in FIG. 2, to the discharge time _{t 10} of the battery 10, the change in the output voltage _{V 10} (voltage between the positive terminal _{TP 10} and the negative terminal _{TN 10)} is relatively small. In addition, since the battery 10 involves an electrochemical reaction during charge and discharge, it is not suitable for rapid charge and discharge (input and output of relatively large current). Moreover, the battery 10 is gradually deteriorated by repeating charging and discharging. For example, the capacity is reduced.

Unlike the battery 10, the capacitor 20 stores electrical energy as it is. For example, an electric double layer capacitor is used as the capacitor 20. The capacitance of the capacitor 20 is, for example, 0.8 Ah. As illustrated in FIG. 3, the change (voltage between the positive terminal _{TP 20} and the negative terminal _{TN 20)} to the discharge time _{t 20} of the capacitor 20, the output voltage _{V 20} is relatively large. Since the capacitor 20 does not involve an electrochemical reaction during charging and discharging, rapid charging and discharging (relatively large current input / output) are possible. Further, compared to the battery 10, the durability is high (hard to deteriorate). However, as described above, the capacity is smaller than that of the battery 10. The scales (magnifications) of the vertical and horizontal axes of the graphs shown in FIGS. 2 and 3 are irrelevant. The graphs shown in FIGS. 2 and 3 are an example. The change characteristic of the output voltage V ₁₀ and the output voltage V ₂₀ is also affected by variations in load.

  The DC power converter 30 is a known bidirectional isolated DC power converter. That is, the DC power converter 30 has a function to lower the voltage of the input power and a function to raise the voltage. As shown in FIG. 1, the DC power converter 30 includes a switching circuit (bridge circuit) SC1 configured of a coil, a capacitor, a plurality of transistors, and the like, a switching circuit (bridge circuit) SC2 and a transformer T. The switching circuit SC1 and the switching circuit SC2 are connected via a transformer T. Therefore, although the switching circuit SC1 and the switching circuit SC2 are electrically isolated, they are electromagnetically connected. In FIG. 1, the plurality of transistors are simply described as switches.

The DC power converter 30 includes an input / output unit 31 (positive electrode terminal TP ₃₁ and negative electrode terminal TN ₃₁ ) and an input / output unit 32 (positive electrode terminal TP ₃₂ and negative electrode terminal TN ₃₂ ). The input / output unit 31 (positive electrode terminal TP ₃₁ and negative electrode terminal TN ₃₁ ) is a terminal unit of the switching circuit SC1 and corresponds to a terminal unit on the opposite side to the transformer T. The input / output unit 32 (positive electrode terminal TP ₃₂ and negative electrode terminal TN ₃₂ ) is a terminal portion of the switching circuit SC 2 and corresponds to a terminal portion on the opposite side to the transformer T. The DC power converter 30 converts DC power input to the input / output unit 31 (between the positive electrode terminal TP ₃₁ and the negative electrode terminal TN ₃₁ ), and converts the DC power into the input / output unit 32 (positive electrode terminal TP ₃₂ and negative electrode terminal TN _32). Output DC power). This operation mode is called a first conversion mode. Further, the DC power converter 30 converts the DC power input to the input / output unit 32 and outputs the DC power to the input / output unit 31. This operation mode is called a second conversion mode. The switching cycle and duty ratio of the on / off states of the plurality of transistors are controlled by a control device 60 described later. Thereby, the operation mode (first conversion mode or second conversion mode) of DC power converter 30 is determined, and the output voltage value from input / output unit 32 in the first conversion mode (positive electrode terminal TP ₃₂ and negative electrode terminal The voltage value between TN ₃₂ and the output voltage value from the input / output unit 31 in the second conversion mode (voltage value between the positive electrode terminal TP ₃₁ and the negative electrode terminal TN ₃₁ ) are controlled. The switching cycle and duty ratio of the on and off states of the plurality of transistors corresponds to the setting signal CS ₃₀ of the present invention.

The DC power converter 40 is a well-known step-down DC power converter. That is, the DC power converter 40 has a function of dropping the voltage of the input power. The DC power converter 40 is configured of, for example, a step-down chopper circuit. The DC power converter 40 includes an input unit 41 (positive electrode terminal TP ₄₁ and negative electrode terminal TN ₄₁ ) and an output unit 42 (positive electrode terminal TP ₄₂ and negative electrode terminal TN ₄₂ ). The input portion 41 (positive electrode terminal TP ₄₁ and negative electrode terminal TN ₄₁ ) corresponds to the terminal portion on the input side (high voltage side) of the step-down chopper circuit. The output unit 42 (positive electrode terminal TP ₄₂ and negative electrode terminal TN ₄₂ ) corresponds to the output terminal (low voltage side) terminal of the step-down chopper circuit. The DC power converter 40 converts DC power (high voltage) input to the input unit 41 (between the positive electrode terminal TP ₄₁ and the negative electrode terminal TN ₄₁ ), and outputs the output unit 42 (positive electrode terminal TP ₄₂ and negative electrode terminal). DC power (low voltage) is output to the TN ₄₂ ). The switching cycle and duty ratio (setting signal CS ₄₀ ) of the on / off states of the plurality of transistors constituting the step-down chopper circuit are controlled by the control device 60 described later. Thus, the output voltage value from the output unit 42 (voltage value between the positive terminal TP ₄₂ and the negative terminal TN ₄₂₎ is controlled.

The switch device 50 includes switches 51 to 53. Switch 51 is provided between the positive terminal _{TP 31} of the positive terminal _{TP 10} and the DC power converter 30 of the battery 10. Switch 52 is provided between the negative terminal _{TN 31} of the positive terminal _{TP 10} and the DC power converter 30 of the battery 10. The switch 53 is provided between the negative electrode terminal TN ₃₁ of the DC power converter 30 and the ground (reference potential) GND.

The negative terminal _{TN 10} of the battery 10, the negative terminal _{TN 20} of the capacitor 20, the DC negative terminal _{TN 32} of power converter 30, the negative terminal _TN 41, _{TN 42} of the DC power converter 40, the negative terminal of the power supply terminal of the auxiliary AC TN _AC, the negative terminal _{TN IV} power terminal of the inverter circuit IV is connected to the ground GND. The positive terminal TP ₃₁ of the DC power converter 30 is connected to the positive terminal TP _IV of the power supply terminal of the inverter circuit IV. The positive terminal _{TP 10} of the battery 10 is connected to the positive terminal _{TP 31} of the DC power converter 30 through the switch 51. Also, the positive terminal _{TP 10} of the battery 10 is connected to the negative terminal _{TN 31} of the DC power converter 30 through the switch 52. The negative terminal TN ₃₁ of the DC power converter 30 is connected to the ground GND via the switch 53. The positive terminal TP ₃₂ of the DC power converter 30 is connected to the positive terminal TP ₂₀ of the capacitor 20. The positive terminal _{TP 20} of the capacitor 20 is connected to the positive terminal _{TP 41} of the DC power converter 40. The positive terminal TP ₄₂ of the DC power converter 40 is connected to the positive terminal TP _AC of the power supply terminal of the accessory AC.

  When the switch 51 is set to the on state, the switch 52 is set to the off state, and the switch 53 is set to the on state (see FIG. 4), the input / output unit 31 is connected in parallel to the battery 10 It corresponds to When the switch 51 is set to the off state, the switch 52 is set to the on state, and the switch 53 is set to the off state (see FIG. 5), the input / output unit 31 is connected in series to the battery 10 It corresponds to When the switch 51 is set to the off state, the switch 52 is set to the off state, and the switch 53 is set to the on state (see FIG. 6), the input / output unit 31 is connected in parallel to the inverter circuit IV. It corresponds to In this state, the battery 10 is disconnected from the input / output unit 31 and the inverter circuit IV. The state in which the switch 51 is set to the on state, the switch 52 is set to the off state, and the switch 53 is set to the off state (see FIG. 7) corresponds to the state in which the battery 10 is connected in parallel to the inverter circuit IV. Do. At this time, the switching circuit SC1 is in a floating state.

The control device 60 includes an arithmetic device and a storage device. The computing device operates in accordance with a computer program stored in the storage device. The arithmetic device switches on / off states of the switches 51 to 53 constituting the switch device 50 based on the speed / acceleration of the vehicle, the depression amount of the accelerator pedal, the depression amount of the brake pedal, and the like. The arithmetic unit also detects the voltage of the power input to DC power converter 30 (output voltage V _{10 of} battery 10, output voltage V 20 of capacitor ₂₀ , and output voltage V _IV of inverter circuit IV at the time of regeneration) Do. The arithmetic unit generates setting signals CS ₃₀ and CS ₄₀ based on the detection result, and outputs the setting signals to DC power converters 30 and 40. The control device 60 may directly detect the speed / acceleration of the vehicle, the depression amount of the accelerator pedal, the depression amount of the brake pedal, etc., and another control device (ECU) that controls the operation of the entire vehicle. From these, those detection results may be acquired.

Below, operation | movement of the power supply system 1 for vehicles is demonstrated concretely. When the driver gets on the vehicle and the control system of the vehicle is activated, the control device 60 executes a start program shown in FIG. When the start-up process is started in step S10, the control device 60 initializes the switch device 50 in the next step S11. That is, the switches 51 to 53 are set to the off state. Next, the control unit 60, at step S12, detects the output voltage _{V 20} of the capacitor 20. Next, in step S13, control device 60 determines whether or not the storage amount of capacitor 20 is sufficient. Specifically, the output voltage _{V 20} where the detected determines whether a predetermined voltage _{VT 20} or more (see FIG. 3 (e.g., more than 12V)). When the output voltage _{V 20} described above detects the predetermined voltage _{VT 20} above, the controller 60 determines "Yes", skips steps S14 and S15 will be described later, ends the start-up process at Step S16 Do.

On the other hand, when the output voltage _{V 20} where the detected is less than a predetermined voltage _{VT 20,} the controller 60 determines a "No", executes the processing of steps S14 and S15, by using the electric power of the battery 10 , Charge the capacitor 20. Specifically, control device 60 operates switch device 50 such that battery 10 and input / output unit 31 are connected in parallel in step S14. That is, the switch 51 is set to the on state, the switch 52 is set to the off state, and the switch 53 is set to the on state (see FIG. 4). Next, at step S15, control device 60 causes DC power converter 30 to function in the first conversion mode, and output voltage V ₃₂ of input / output unit 32 of DC power converter 30 has a predetermined voltage (auxiliary device It generates a set signal _{CS 30} such that AC power supply voltage (e.g., 15V)) and outputs. Thereby, capacitor 20 is charged using the power of battery 10. Then, in step S16, the control device 60 ends the start-up process. In the start process, the traveling motor MT is stopped.

Next, control device 60 generates and outputs setting signal CS ₄₀ such that output voltage V ₄₂ of output unit 42 of DC power converter 40 becomes the power supply voltage (for example, 15 V) of auxiliary device AC. That is, the output voltage V ₂₀ of the capacitor 20 even if variations, power supply voltage of the auxiliary AC is kept constant.

Next, the control device 60 detects the control state (rotational driving state or regenerative braking state) of the traveling motor MT based on the speed / acceleration of the vehicle, the depression amount of the accelerator pedal, the depression amount of the brake pedal, and the like. When the control device 60 detects that the traveling motor MT is shifted to the rotational driving state, the control device 60 executes a discharge program shown in FIG. 9 to supply the power of the battery 10 and the capacitor 20 to the inverter circuit IV. Control device 60 starts the discharge process in step S20. Next, in step S21, the control device 60 operates the switch device 50 so that the battery 10 and the input / output unit 31 are connected in series. That is, the switch 51 is set to the off state, the switch 52 is set to the on state, and the switch 53 is set to the off state (see FIG. 5). Next, the control unit 60, at step S22, detects the output voltage _{V 10} of the battery 10. Next, the control unit 60, at step S23, the DC power converter 30 functions in the second conversion mode, and the output voltage V of the input-output unit 31 between the output voltage V ₁₀ where the detected DC power converter 30 the sum of _{31 (V} 10 ₊ V ₃₁₎ generates and outputs a set signal _{CS 30} as equal to the rated supply voltage of the inverter circuit IV. Then, control device 60 advances the process to step S22. Control device 60 repeatedly executes a series of processes consisting of step S22 and step S23. As shown in FIG. 2, the output voltage V ₁₀ of the battery 10 is gradually reduced with the lapse of the discharge time t ₁₀ (decrease of the charged amount), the decrease amount (portion hatched in FIG. 2) is, The DC power converter 30 compensates by boosting or stepping down the output voltage V ₂₀ of the capacitor 20. When it is detected that the traveling motor MT is shifted to the regenerative braking state during the discharge process, the control device 60 ends the discharge process, and shifts to a charge process to be described next.

When control device 60 detects that traveling motor MT is shifted to the regenerative braking state, control device 60 executes a charging program shown in FIG. 10 to charge capacitor 20 or battery 10 using the regenerative power. Do. Control device 60 starts the charging process in step S30. Next, the control unit 60, at step S31, detects the output voltage _{V 20} of the capacitor 20. Next, in step S32, control device 60 determines whether or not capacitor 20 can be charged using the regenerative power output from inverter circuit IV. Specifically, the output voltage V ₂₀ described above detects, determines whether a predetermined voltage VT ₂₀ above. Output voltage _{V 20} described above detects, when less than the predetermined voltage _{VT 20,} controller 60, "Yes" (i.e., the capacitor 20 can be charged) determines that, the process proceeds to step S33.

Next, in step S33, control device 60 operates switch device 50 such that inverter circuit IV and input / output unit 31 are connected in parallel. That is, the switch 51 is set to the on state, the switch 52 is set to the off state, and the switch 53 is set to the on state (see FIG. 6). Next, at step S34, control device 60 operates DC power converter 30 in the first conversion mode, and output voltage V ₃₂ of input / output unit 32 of DC power converter 30 is at a predetermined voltage It generates a set signal _{CS 30} such that AC power supply voltage (e.g., 15V)) and outputs. Thereby, capacitor 20 is charged using the regenerative power output from inverter circuit IV. The regenerative power is also used to drive the accessory AC. Then, control device 60 advances the process to step S32.

On the other hand, in step S32, the output voltage _{V 20} described above detects, when the predetermined voltage _{VT 20} above, the controller 60 determines a "No" (i.e., non charging capacitor 20). That is, control device 60 determines that the storage amount of capacitor 20 is sufficient. In this case, control device 60 charges battery 10 using the regenerative power output from inverter circuit IV.

  At step S35, control device 60 operates switch device 50 such that inverter circuit IV and battery 10 are connected in parallel. That is, the switch 51 is set to the on state, the switch 52 is set to the off state, and the switch 53 is set to the off state (see FIG. 7). In this state, DC power converter 30 is stopped, and accessory AC is driven using the power of capacitor 20. Then, control device 60 advances the process to step S32.

  As described above, in the present embodiment, the capacitor 20 is preferentially charged using the regenerative power output from the inverter circuit IV during regenerative braking of the traveling motor MT. When it is detected that the traveling motor MT is shifted to the rotational driving state, the control device 60 ends the charging process and shifts to the discharging process. Thus, while the vehicle is traveling, the discharge process and the charge process are alternately performed.

As described above, in the vehicle power supply system 1, the power of the capacitor 20 is converted by the DC power converter 30 and output from the input / output unit 31. The battery 10 and the input / output unit 31 are connected in series. In this state, as the sum of the output voltage _{V 31} of the output unit 31 of the output voltage _{V 10} and the DC power converter 30 of the battery 10 _(V 10 ₊ V ₃₁₎ is equal to the rated supply voltage of the inverter circuit IV, The DC power converter 30 is controlled. Thus, the power supply voltage of inverter circuit IV can be maintained at the rated power supply voltage. Thus, the traveling motor MT can always be driven efficiently.

  In addition, capacitor 20 having relatively high durability (not easily deteriorated) is preferentially charged using regenerative power. Therefore, the number of times of charging and discharging of the battery 10 can be reduced. Therefore, deterioration of the battery 10 can be suppressed.

  Furthermore, the implementation of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  In the above embodiment, a lithium ion battery is adopted as the battery 10, but another type of secondary battery may be adopted. Further, although an electric double layer capacitor is employed as the capacitor 20, capacitors of other types may be employed. Also, although an apparatus connected between switching circuit SC1 and switching circuit SC2 via transformer T is adopted as DC power converter 30, power is bidirectionally input / output unit 31 and input / output unit 32. A device of another type may be adopted as long as it can be converted and the circuit on the side of the input / output unit 31 and the circuit on the side of the input / output unit 32 are electrically isolated.

  If the power supply voltage values of the devices (air conditioner, audio device, lighting device, etc.) constituting the accessory AC are different, the DC power converter 40 may be provided for each of the devices.

In addition, in discharge processing, the sum (V ₁₀ + V ₃₁ ) of output voltage V ₁₀ and output voltage V ₃₁ is higher than the rated power supply voltage of inverter circuit IV in order to correspond to a high load temporarily (for example, at high speed traveling). The DC power converter 30 may be controlled to be slightly higher.

DESCRIPTION OF SYMBOLS 1 ... Power supply system for vehicles, 10 ... Battery, 20 ... Capacitor, 30, 40 ... DC power converter, 31 ... Input-output part, 32 ... Input-output part, 41 · · Input unit, 42 · · · Output unit, 51 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · control device, AC · · · auxiliary equipment, CS ₃₀ , CS ₄₀ · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Setting signal _{transformer, V 10, V 20, V} 31, V 32, V 42 ··· output _{voltage, t 10} · · · discharge _{time, t 20} · · · discharge time

Claims (4)

An inverter circuit having a function of driving a traveling motor of a vehicle and a function of outputting regenerative power; and a first power storage device and a second power storage device for storing power supplied to an accessory of the vehicle;
A first input / output unit connected to the first power storage device and the inverter circuit, and a second input / output unit connected to the second power storage device and the auxiliary device, according to a setting signal for setting an output voltage value A bidirectional isolated DC power converter that changes a voltage of DC power supplied to one input / output unit and outputs the voltage from the other input / output unit;
A plurality of switches for switching the connection of the first input / output unit, the first power storage device, and the inverter circuit;
By generating and outputting the setting signal according to the voltage of the power input to the bidirectional isolated power converter, the on / off states of the plurality of switches are set to predetermined states, respectively. A state in which the first power storage device and the first input / output unit are connected in parallel, a state in which the inverter circuit and the first input / output portion are connected in parallel, or the first power storage device and the first input / output A control unit configured to set a state in which a circuit formed by connecting the first power storage device and the first input / output unit in series is connected in parallel to the inverter circuit;
Power supply system for vehicles equipped with. In the vehicle power supply system according to claim 1,
The first power storage device is a device that converts electrical energy into chemical energy and stores it, and converts the stored chemical energy into electrical energy and releases it.
The second power storage device is a device for storing electric energy as it is and releasing the stored electric energy as it is. In the vehicle power supply system according to claim 2,
The vehicle power supply system, wherein the second power storage device is a capacitor. The vehicle power supply system according to claim 1 or 2
The control device sets a state in which the first power storage device is disconnected from the first input / output unit and the inverter circuit in a state where the inverter circuit and the first input / output unit are connected in parallel. Power supply system.

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