JP4702333B2 - Power supply system and electric vehicle equipped with the same - Google Patents

Description

  The present invention relates to a power supply system and an electric vehicle including the same, and more particularly to control of a power supply system including a plurality of voltage converters connected in parallel.

  Japanese Patent No. 3797361 discloses a motor drive control device that controls the drive of a motor by supplying the output of a DC power source to the motor via an inverter. The motor drive control device includes a converter that converts an output voltage from a DC power supply and supplies the converted voltage to an inverter, and a control unit that performs PWM control on the inverter and controls a supply current to the motor. The control unit calculates an optimal inverter input voltage target value that can realize the required power of the motor based on the rotation speed of the motor and the target output torque, and controls the converter so that the input voltage target value is obtained.

According to this motor drive control device, efficient operation of the motor by applying an optimum voltage can be realized based on the operation state of the motor (see Patent Document 1).
Japanese Patent No. 3797361

  In an electric vehicle equipped with the motor drive control device as described above, in recent years, the capacity of a direct current power source has been increased in order to improve traveling performance such as acceleration performance and traveling distance. As a means for increasing the capacity of the DC power supply, a configuration in which a plurality of power storage devices are connected in parallel has been proposed.

  When a plurality of power storage devices are connected in parallel, it is necessary to provide a converter for each power storage device in order to control input / output of each power storage device. And in such a structure, it becomes a subject to be able to mount the converter added accompanying parallel connection of an electrical storage apparatus as low as possible in the said patent 397361, Such a subject No information is disclosed about the solution.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a power supply system capable of increasing the capacity of a DC power supply at low cost and an electric vehicle equipped with the power supply system. .

  According to this invention, the power supply system is a power supply system capable of transferring power to and from the load device, the power line for transferring power between the power supply system and the load device, the first and the chargeable / dischargeable first and A second power storage device, a water-cooled first voltage converter, an air-cooled second voltage converter, and a control device are provided. The first voltage conversion device is provided corresponding to the first power storage device, and is configured to be capable of voltage conversion between the first power storage device and the power line. The second voltage conversion device is provided corresponding to the second power storage device, and is configured to be capable of voltage conversion between the second power storage device and the power line. When the required power for the power supply system is less than or equal to the reference value, the control device includes the first and the second voltage converters such that the share ratio of the required power borne by the first voltage converter is greater than the share ratio of the second voltage converter. The second voltage converter is controlled. Then, when the required power exceeds the reference value, the control device controls the first and second voltage converters so that the sharing ratio of the second voltage converter increases as the required power increases.

Preferably, the reference value is a maximum power value at which the first voltage conversion device can be energized.
Preferably, the control device stops the second voltage conversion device when the required power is equal to or less than a reference value.

  Preferably, the power supply system further includes a temperature detection device that detects the temperature of the cooling air supplied to the second voltage conversion device. The control device controls the first and second voltage conversion devices such that the sharing ratio of the second voltage conversion device increases with a decrease in temperature.

  Preferably, the power supply system further includes a temperature detection device that detects the temperature of the second voltage conversion device. The control device controls the first and second voltage conversion devices such that the sharing ratio of the second voltage conversion device increases with a decrease in temperature.

  In addition, according to the present invention, an electric vehicle includes any one of the power supply systems described above, a driving force generation unit, a radiator, and an air cooling device. The driving force generation unit receives the supply of electric power from the power supply system and generates the driving force of the vehicle. The radiator cools the refrigerant of the first voltage conversion device included in the power supply system. The air cooling device cools the second voltage conversion device included in the power supply system. The radiator is disposed at the forefront of the vehicle, the first voltage conversion device is disposed at the front of the vehicle, and the second voltage conversion device and the air cooling device are disposed at the rear of the vehicle.

  In the present invention, the second power storage device and the second voltage conversion device are provided in parallel with the first power storage device and the first voltage conversion device. Here, since the second voltage conversion device is air-cooled and can be added at low cost, the cooling performance is relatively inferior to that of the water-cooled first voltage conversion device. Therefore, when the required power for the power supply system is less than or equal to the reference value, the control device sets the share ratio of the required power borne by the first voltage converter to be greater than the share ratio of the second voltage converter. Control the first and second voltage converters. Thereby, the energization amount of the 2nd voltage converter is controlled, and the temperature rise of the 2nd voltage converter is controlled. Then, when the required power exceeds the reference value, the control device controls the first and second voltage converters so that the sharing ratio of the second voltage converter increases as the required power increases. As a result, power that is insufficient in the first voltage converter is assisted by the second voltage converter.

  Therefore, according to the present invention, by adopting the air-cooled second voltage converter, it is possible to increase the capacity of the DC power supply at a low cost.

  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]
1 is an overall block diagram of a hybrid vehicle shown as an example of an electric vehicle equipped with a power supply system according to Embodiment 1 of the present invention. Referring to FIG. 1, hybrid vehicle 100 includes a power supply system 1, inverters 20 and 22, motor generators MG 1 and MG 2, an engine 2, a power split mechanism 4, and wheels 6.

  This hybrid vehicle 100 travels using engine 2 and motor generator MG2 as power sources. Power split device 4 is coupled to engine 2 and motor generators MG1, MG2 to distribute power between them. Power split device 4 is composed of, for example, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary carrier, and a ring gear, and these three rotation shafts are connected to the rotation shafts of engine 2 and motor generators MG1, MG2, respectively. It should be noted that engine 2 and motor generators MG1, MG2 can be mechanically connected to power split mechanism 4 by hollowing the rotor of motor generator MG1 and passing the crankshaft of engine 2 through the center thereof. Further, the rotation shaft of motor generator MG2 is coupled to wheel 6 by a reduction gear or a differential gear (not shown).

  Motor generator MG1 operates as a generator driven by engine 2 and is incorporated in hybrid vehicle 100 as an electric motor that can start engine 2, and motor generator MG2 drives wheels 6. As an electric motor, the hybrid vehicle 100 is incorporated.

  The power supply system 1 includes power storage devices B1 and B2, converters 10 and 12, a capacitor C, an ECU (Electronic Control Unit) 30, voltage sensors 42, 44, and 46, current sensors 52 and 54, and an outside air temperature sensor. 62.

  The power storage devices B1 and B2 are DC power sources that can be charged and discharged, and include, for example, secondary batteries such as nickel metal hydride and lithium ions. Power storage device B1 supplies power to converter 10 and is charged by converter 10 during power regeneration. Power storage device B2 supplies power to converter 12 and is charged by converter 12 during power regeneration.

  For example, a secondary battery having a maximum outputable power larger than that of power storage device B2 can be used for power storage device B1, and a secondary battery having a larger storage capacity than power storage device B1 can be used for power storage device B2. be able to. Thus, a high-power and large-capacity DC power source can be configured using the two power storage devices B1 and B2. Further, a large-capacity capacitor may be used for at least one of the power storage devices B1 and B2.

  Converter 10 is a water-cooled voltage converter. Based on signal PWC1 from ECU 30, converter 10 performs voltage conversion between power storage device B1 and a power line pair including positive line PL3 and negative line NL.

  Converter 12 is an air-cooled voltage converter, and is connected in parallel to converter 10 to positive line PL3 and negative line NL. Converter 12 performs voltage conversion between power storage device B2 and a power line pair formed of positive electrode line PL3 and negative electrode line NL based on signal PWC2 from ECU 30. Since converter 12 is air-cooled, the cost is lower than that of water-cooled converter 10, but the cooling performance is inferior. The circuit configuration of converters 10 and 12 will be described in detail later.

  Capacitor C is connected between positive electrode line PL3 and negative electrode line NL, and smoothes voltage fluctuations between positive electrode line PL3 and negative electrode line NL.

  Inverter 20 converts a DC voltage from positive line PL3 into a three-phase AC voltage based on signal PWI1 from ECU 30, and outputs the converted three-phase AC voltage to motor generator MG1. Inverter 20 converts the three-phase AC voltage generated by motor generator MG1 using the power of engine 2 into a DC voltage based on signal PWI1, and outputs the converted DC voltage to positive line PL3.

  Inverter 22 converts a DC voltage from positive line PL3 into a three-phase AC voltage based on signal PWI2 from ECU 30, and outputs the converted three-phase AC voltage to motor generator MG2. Further, the inverter 22 converts the three-phase AC voltage generated by the motor generator MG2 in response to the rotational force from the wheels 6 into a DC voltage based on the signal PWI2 when braking the vehicle or reducing acceleration on a downward slope, The converted DC voltage is output to positive line PL3.

  In addition, each inverter 20 and 22 consists of a bridge circuit containing the switching element for three phases, for example. Inverters 20 and 22 drive corresponding motor generators by performing switching operations in accordance with signals PWI1 and PWI2 from ECU 30, respectively.

  Each of motor generators MG1 and MG2 is a three-phase AC rotating electric machine, for example, a three-phase AC synchronous motor generator. Motor generator MG1 is regeneratively driven by inverter 20, and outputs a three-phase AC voltage generated using the power of engine 2 to inverter 20. Motor generator MG1 is driven by power by inverter 20 when engine 2 is started, and cranks engine 2. Motor generator MG <b> 2 is driven by power by inverter 22, and generates a driving force for driving wheels 6. Motor generator MG2 is regeneratively driven by inverter 22 when the vehicle is braked or when acceleration is reduced on a downward slope, and outputs to inverter 22 a three-phase AC voltage generated using the rotational force received from wheels 6.

  Voltage sensor 42 detects voltage VB1 of power storage device B1 and outputs the detected value to ECU 30. Voltage sensor 44 detects voltage VB2 of power storage device B2, and outputs the detected value to ECU 30. Current sensor 52 detects current I1 input / output to / from power storage device B1, and outputs the detected value to ECU 30. Current sensor 54 detects current I2 input to and output from power storage device B2, and outputs the detected value to ECU 30. Voltage sensor 46 detects a voltage between terminals of capacitor C, that is, voltage VH of positive line PL3 with respect to negative line NL, and outputs the detected value to ECU 30.

  The outside air temperature sensor 62 detects the temperature T of the outside air around the vehicle and outputs the detected value to the ECU 30. The outside air temperature sensor 62 detects the temperature of the cooling air sucked from the outside of the vehicle in order to cool the air-cooled converter 12.

  ECU 30 generates signals PWC1 and PWC2 for driving converters 10 and 12, respectively, and outputs the generated signals PWC1 and PWC2 to converters 10 and 12, respectively. Here, ECU 30 determines the sharing ratio of converters 10 and 12 according to a method described later in accordance with the power required for power supply system 1 (hereinafter simply referred to as “required power”) P, and the required power P Then, signals PWC1 and PWC2 are generated according to the determined sharing ratio. The required power P is calculated by a vehicle ECU (not shown) based on the accelerator pedal opening, the vehicle speed, and the like.

  ECU 30 also generates signals PWI1 and PWI2 for driving inverters 20 and 22, respectively, and outputs the generated signals PWI1 and PWI2 to inverters 20 and 22, respectively.

  FIG. 2 is a schematic plan view of hybrid vehicle 100 for describing the arrangement configuration of converters 10 and 12 shown in FIG. In FIG. 2, only the portions necessary for explaining the arrangement configuration of converters 10 and 12 are shown, and the other configurations are not shown.

  Referring to FIG. 2, hybrid vehicle 100 includes front wheels FR and FL, rear wheels RR and RL, power storage pack 70, converter 10, radiator 72, cooling water channel 74, converter 12, and intake duct 78. And a cooling fan 80 and an exhaust duct 82.

  Converter 10 is arranged in an engine room in front of the vehicle, together with engine 2, inverters 20 and 22, motor generators MG1 and MG2, which are not shown. A radiator 72 is provided in the foremost part of the vehicle, and the cooling water circulates between the converter 10 and the radiator 72 via the cooling water passage 74.

  Converter 12 is disposed, for example, behind a rear seat (not shown). The outside air taken into the intake duct 78 from the intake port 76 provided on the side of the vehicle is supplied to the converter 12 by the cooling fan 80, and the cooling air that has exchanged heat with the converter 12 passes through the exhaust duct 82. And discharged from the exhaust port 84 provided at the rear of the vehicle.

  Power storage pack 70 includes power storage devices B1 and B2 (not shown), and is disposed, for example, at the rear of the rear seat or the lower portion of the rear seat. Converter 10 exchanges power with power storage device B1 in power storage pack 70, and converter 12 transfers power with power storage device B2 in power storage pack 70.

  FIG. 3 is a circuit diagram of converters 10 and 12 shown in FIG. Referring to FIG. 3, converter 10 (12) includes transistors Q1 and Q2, diodes D1 and D2, and a coil CL. Transistors Q1 and Q2 are connected in series between positive line PL3 and negative line NL. Diodes D1 and D2 are connected in antiparallel to transistors Q1 and Q2, respectively. One end of coil CL is connected to the connection node of transistors Q1 and Q2, and the other end is connected to positive electrode line PL1 (PL2). In addition, as said transistor, power switching elements, such as IGBT (Insulated Gate Bipolar Transistor) and power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), can be used, for example.

  This converter 10 (12) comprises a chopper circuit. Converter 10 (12) boosts the voltage of positive line PL1 (PL2) using coil CL based on signal PWC1 (PWC2) from ECU 30 (not shown), and the boosted voltage is positive line. Output to PL3.

  Specifically, converter 10 (12) accumulates the current that flows when transistor Q2 is turned on as magnetic field energy in coil CL, and the accumulated energy is transferred to diode D1 in synchronization with the timing when transistor Q2 is turned off. To the positive electrode line PL3, the voltage of the positive electrode line PL3 is boosted to a voltage higher than that of the positive electrode line PL1.

  The amount of current exchanged between positive electrode line PL1 and positive electrode line PL3 is determined by the duty ratio of transistors Q1 and Q2. That is, as the on-duty ratio of transistor Q2 increases, the energy stored in coil CL increases, so the current flowing from positive line PL1 to positive line PL3 increases. On the other hand, when the on-duty ratio of the transistor Q1 increases, the current flowing from the high-voltage side positive line PL3 to the low-voltage side positive line PL1 increases.

  FIG. 4 is a functional block diagram of ECU 30 shown in FIG. Referring to FIG. 4, ECU 30 includes a converter control unit 32 and inverter control units 34 and 36.

  Converter control unit 32 turns on / off transistors Q1 and Q2 of converters 10 and 12 based on detected values of voltages VB1, VB2 and VH, currents I1 and I2 and temperature T, and required power P, respectively. PWM (Pulse Width Modulation) signals are generated in accordance with a control structure described later, and the generated PWM signals are output to converters 10 and 12 as signals PWC1 and PWC2, respectively.

  Inverter control unit 34 turns on the transistor included in inverter 20 based on torque command value TR1 of motor generator MG1, each detected value of motor current MCRT1 and rotor rotation angle θ1 of motor generator MG1, and detected value of voltage VH. A PWM signal for turning off / off is generated, and the generated PWM signal is output to the inverter 20 as a signal PWI1.

  Inverter control unit 36 turns on the transistor included in inverter 22 based on torque command value TR2 of motor generator MG2, each detected value of motor current MCRT2 and rotor rotation angle θ2 of motor generator MG2, and detected value of voltage VH. A PWM signal for turning off / off is generated, and the generated PWM signal is output to the inverter 22 as a signal PWI2.

  Torque command values TR1 and TR2 are calculated by a vehicle ECU (not shown) based on, for example, the accelerator opening, the brake depression amount, the vehicle speed, and the like. Motor currents MCRT1 and MCRT2 and rotor rotation angles θ1 and θ2 are detected by sensors (not shown).

  FIG. 5 is a detailed functional block diagram of converter control unit 32 shown in FIG. Referring to FIG. 5, converter control unit 32 includes a power distribution setting unit 102, a target value setting unit 104, and signal generation units 106-1 and 106-2.

  Based on the required power P and the detected value of temperature T, power distribution setting unit 102 sets the sharing ratio of converters 10 and 12 to required power P.

  FIG. 6 is a diagram showing the sharing ratio of converters 10 and 12 set by power distribution setting unit 102 shown in FIG. Referring to FIG. 6, the horizontal axis indicates the required power P, and the vertical axis indicates the share ratio r (%) of converter 10 with respect to required power P. That is, the sharing ratio of the converter 12 is (100−r)%.

  The threshold value Pth1 of the required power P is set to, for example, the maximum power value that can be applied to the converter 10. The threshold value Pth2 is set to a value larger than the threshold value Pth1, and is set to, for example, a value obtained by adding the maximum power that can be supplied to the converter 12 to the maximum power that can be supplied to the converter 10. When the required power P is less than or equal to the threshold value Pth1, the sharing ratio r is set to (100−α)% (α will be described later), and when the required power P exceeds the threshold value Pth1, the required power P As the ratio increases, the sharing ratio r decreases (that is, the sharing ratio of the converter 12 increases as the required power P increases). When the required power P exceeds the threshold value Pth2, the sharing ratio r is set to 50%.

  As described above, in the region where the required power P is relatively small, the sharing ratio of the converter 10 is increased and the sharing ratio of the converter 12 is decreased. In the region where the required power P is relatively large, the increase in the required power P is increased. The reason why the sharing ratio of the converter 10 is decreased and the sharing ratio of the converter 12 is increased is as follows.

  That is, as described above, the air-cooled converter 12 is inferior in cooling performance to the water-cooled converter 10 and is more likely to be subjected to output limitation due to temperature rise than the converter 10. Therefore, in a region where the required power P is relatively small, when the sharing ratio of the converter 12 is lowered, the converter 12 is given a thermal margin, and the required power P increases and the load on the converter 12 increases. In the converter 12, the output restriction due to the temperature rise is avoided as much as possible.

Here, the above-described sharing ratio r is corrected by a correction value α that changes according to the temperature T.
FIG. 7 is a diagram showing the relationship between the temperature T and the correction value α. Referring to FIG. 7, the correction value α increases as the temperature T decreases. When the temperature T exceeds the threshold value Tth1, the correction value α becomes 0.

  Therefore, referring again to FIG. 6, the lower the temperature T, the larger the correction value α, and the lower the sharing ratio r. The reason why the sharing ratio r is corrected according to the temperature T is as follows. That is, it is preferable to balance the power storage states of power storage devices B1 and B2 (hereinafter referred to as “SOC (State of Charge)”) as much as possible. Therefore, when the temperature T is low and the cooling performance of the converter 12 is high, the converter 12 is unlikely to be subjected to output limitation due to temperature rise, so the sharing ratio r is reduced, that is, the sharing ratio of the converters 10 and 12 is equalized. By approaching the direction, the SOCs of the power storage devices B1 and B2 are balanced as much as possible.

  Referring to FIG. 5 again, power distribution setting unit 102 sets sharing ratio r according to the relationships shown in FIGS. 6 and 7, and outputs the set sharing ratio r to target value setting unit 104.

  The target value setting unit 104 calculates the target value VR of the voltage VH and the target value IR of the current I2 based on the required power P, the sharing ratio r set by the power distribution setting unit 102, and the detected values of the voltages VB1 and VB2. Set. Specifically, the target value setting unit 104 sets a specified voltage higher than the voltages VB1 and VB2 as the target value VR. Target value setting unit 104 calculates the power target value of converter 12 by multiplying the required power P by the sharing ratio (100-r) of converter 12 and divides the calculated power target value by voltage VB2. As a result, the target value IR is calculated.

  Signal generation unit 106-1 includes subtraction units 108-1, 112-1, a proportional integration control unit 110-1, and a modulation unit 114-1. Subtraction unit 108-1 subtracts voltage VH from target value VR set by target value setting unit 104, and outputs the calculation result to proportional-plus-integral control unit 110-1. The proportional-plus-integral control unit 110-1 performs a proportional-integral calculation with the deviation between the target value VR and the voltage VH as an input, and outputs the calculation result to the subtracting unit 112-1. The subtraction unit 108-1 and the proportional integration control unit 110-1 constitute a voltage feedback control element.

  The subtracting unit 112-1 subtracts the output of the proportional-integral control unit 110-1 from the inverse of the theoretical boost ratio of the converter 10 indicated by the voltage value VB1 / target value VR, and uses the calculation result as the duty command Ton1 as the modulation unit 114. Output to -1.

  Modulation section 114-1 generates signal PWC 1 based on duty command Ton 1 and a carrier wave (carrier wave) generated by an oscillation section (not shown), and generates the generated signal PWC 1 to transistors Q 1 and Q 2 of converter 10. Output.

  Duty command Ton1 input to modulation unit 114-1 corresponds to the on-duty ratio of transistor Q1 constituting the upper arm of converter 10, and takes a value from 0 to 1. Converter 10 is controlled such that the step-up ratio decreases as duty command Ton1 increases, and the step-up ratio increases as duty command Ton1 decreases.

  Signal generation unit 106-2 includes subtraction units 108-2 and 112-2, proportional-integral control unit 110-2, and modulation unit 114-2. Subtraction unit 108-2 subtracts current I2 from target value IR set by target value setting unit 104, and outputs the calculation result to proportional-plus-integral control unit 110-2. The proportional-plus-integral control unit 110-2 performs a proportional-integral calculation with the deviation between the target value IR and the current I2 as input, and outputs the calculation result to the subtracting unit 112-2. The subtraction unit 108-2 and the proportional-plus-integral control unit 110-2 constitute a current feedback control element.

  Subtraction unit 112-2 subtracts the output of proportional-integral control unit 110-2 from the inverse of the theoretical boost ratio of converter 12 indicated by voltage value VB2 / target value VR, and uses the calculation result as duty command Ton2, modulating unit 114. Output to -2.

  Modulation section 114-2 generates signal PWC 2 based on duty command Ton 2 and a carrier wave (carrier wave) generated by an oscillation section (not shown), and generates the generated signal PWC 2 to transistors Q 1 and Q 2 of converter 12. Output.

  The duty command Ton2 input to the modulation unit 114-2 corresponds to the on-duty ratio of the transistor Q1 constituting the upper arm of the converter 12, and takes a value from 0 to 1.

  In converter control unit 32, power distribution setting unit 102 sets the sharing ratio of converters 10 and 12, and target value setting unit 104 sets target value VR of voltage VH and target value IR of current I2. Signal generation unit 106-1 generates signal PWC1 for controlling voltage VH to target value VR, and signal generation unit 106-2 provides converter 12 for outputting power according to the set sharing ratio. Signal PWC2 is generated. Although the converter 10 does not actively control the power, by controlling the power of the converter 12 and controlling the voltage VH to the target value VR by the converter 10, the output power of the converter 10 is consequently shared. Follow r.

  In the above description, the correction value α may always be 0, and the converter 12 may be shut down when the required power P is equal to or less than the threshold value Pth1. In this case, when requested power P is equal to or lower than threshold value Pth1, power distribution setting unit 102 generates signal SD for requesting shutdown of converter 12 and outputs the signal to converter 12, and converter 12 receives signal SD. Shut down.

  In the above description, threshold value Pth1 is set to the maximum power value at which converter 10 can be energized, but may be set to a value smaller than the maximum power at which converter 10 can be energized. The threshold value Pth2 is set to a value obtained by adding the maximum power that can be energized by the converter 10 to the maximum power that can be energized by the converter 12. However, the threshold Pth2 is within a range that is larger than the threshold Pth1. You may set to a value smaller than the total value of the maximum power of 10,12.

  As described above, in the first embodiment, power supply system 1 includes power storage device B2 and converter 12 in addition to power storage device B1 and converter 10. Although the converter 12 is air-cooled and low in cost, the cooling performance is relatively inferior to that of the water-cooled converter 10. Therefore, ECU 30 controls converters 10 and 12 such that the sharing ratio of converter 10 is greater than the sharing ratio of converter 12 when required power P for power supply system 1 is equal to or less than threshold value Pth1. Thereby, the energization amount of converter 12 is suppressed, and the temperature rise of converter 12 is suppressed. Then, when required power P exceeds threshold value Pth1, ECU 30 controls converters 10 and 12 such that the sharing ratio of converter 12 increases as required power P increases. As a result, power that is insufficient in converter 10 is assisted by converter 12. Therefore, according to the first embodiment, the adoption of the air-cooled converter 12 can increase the capacity of the power supply system 1 at a low cost.

  In addition, according to the first embodiment, converter 12 is arranged at the rear of the vehicle, so that converter 12 can be easily additionally mounted without changing the device layout in the engine room.

  Further, according to the first embodiment, since the sharing ratio of converters 10 and 12 is corrected by correction value α that varies with temperature T, the balance of SOC of power storage devices B1 and B2 is also taken into consideration The sharing ratio of converters 10 and 12 can be appropriately set according to the environment.

  If the correction value α is always 0 and the converter 12 is shut down when the required power P is less than or equal to the threshold value Pth1, loss in the converter 12 can be reduced.

[Modification 1]
As described above, it is preferable to balance the SOCs of power storage devices B1 and B2 as much as possible. Therefore, in addition to correcting the sharing ratio of converters 10 and 12 with correction value α, the converter 12 is within a range in which the heat generation of converter 12 does not increase. 12 may share power.

  FIG. 8 is a diagram showing the sharing ratio of converters 10 and 12 in the first modification. Referring to FIG. 8, when required power P is equal to or less than threshold value Pth1, sharing ratio r is set to (100−α−Δr)%. Here, offset value Δr is set to an appropriate value that allows converter 12 to have a thermal margin in consideration of the SOC balance of power storage devices B1 and B2.

  If required power P exceeds threshold value Pth1, share ratio r decreases as request power P increases (that is, the share ratio of converter 12 increases as request power P increases). When the threshold value Pth2 is exceeded, the sharing ratio r is set to 50%, as in the first embodiment.

[Modification 2]
FIG. 9 is a diagram showing the sharing ratio of converters 10 and 12 in the second modification. Referring to FIG. 9, when required power P is 0, sharing ratio r is set to 100%, and sharing ratio r decreases as required power P increases. That is, when the required power P is 0, the sharing ratio of the converter 12 is 0, and the sharing ratio of the converter 12 increases as the required power P increases. When the required power P exceeds the threshold value Pth2, the sharing ratio r is set to 50%.

  Also according to the second modification, it is possible to allow the converter 12 to have a thermal margin while considering the SOC balance of the power storage devices B1 and B2.

[Embodiment 2]
In Embodiment 2, instead of outside air temperature sensor 62, the temperatures of converters 10 and 12 are detected, and correction value α is set according to the detected temperature.

  FIG. 10 is an overall block diagram of a hybrid vehicle shown as an example of an electric vehicle equipped with the power supply system according to the second embodiment. Referring to FIG. 10, hybrid vehicle 100 </ b> A includes power supply system 1 </ b> A instead of power supply system 1 in the configuration of hybrid vehicle 100 in the first embodiment shown in FIG. 1. Power supply system 1 </ b> A includes temperature sensors 64 and 66 instead of outside air temperature sensor 62 in the configuration of power supply system 1.

  Temperature sensor 64 detects temperature T1 of converter 10 and outputs the detected value to ECU 30. Temperature sensor 66 detects temperature T2 of converter 12 and outputs the detected value to ECU 30.

  The other configuration of hybrid vehicle 100A is the same as that of hybrid vehicle 100.

  FIG. 11 is a diagram showing the correction value α in the second embodiment. Referring to FIG. 11, the correction value α increases as the temperature T2 of the converter 12 decreases. When the temperature T2 is equal to or higher than the threshold value Tth2, the correction value α is 0.

  In the second embodiment, the lower the temperature T2 of the converter 12, the lower the possibility that the converter 12 will be subjected to output limitation due to the temperature rise. Therefore, the sharing ratio r is reduced, that is, the sharing ratios of the converters 10 and 12 are equalized. By approaching the direction, the SOCs of the power storage devices B1 and B2 are balanced as much as possible.

Note that the temperature T1 of the converter 10 may be reflected in the correction value α.
FIG. 12 is a diagram showing the temperature T1 of the converter 10 and the correction value α. Referring to FIG. 12, when temperature T1 of converter 10 exceeds threshold value Tth3, correction value α increases as temperature T1 increases.

  Therefore, as the temperature T1 of the converter 10 increases, the correction value α increases, so the maximum value of the sharing ratio r of the converter 10 decreases. That is, the burden on the converter 10 is reduced, and it is possible to avoid as much as possible the output limitation in the converter 10 due to the temperature rise.

  Note that the correction value α may be determined according to the temperatures T1 and T2 by appropriately weighting the temperature T1 of the converter 10 and the temperature T2 of the converter 12.

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained.

  In each of the above embodiments, when required power P exceeds threshold value Pth2, the sharing ratio of converters 10 and 12 is set to 50%, but this set value is other than 50%. There may be. For example, you may set to the value according to the capacity | capacitance of electrical storage apparatus B1, B2.

  In each of the above embodiments, the water-cooled converter 10 is voltage feedback control based on the voltage VH, and the air-cooled converter 12 is current feedback control (power feedback control) based on the current I2. Control of converters 10 and 12 is not limited to these controls. However, at least one of converters 10 and 12 needs to perform power control or current control.

  In each of the above embodiments, a so-called series / parallel type hybrid vehicle in which the power of the engine 2 is distributed to the motor generator MG1 and the wheels 6 using the power split mechanism 4 has been described. The present invention is also applicable to a so-called series type hybrid vehicle that uses only the power generated by the motor generator MG1 and generates the driving force of the vehicle using only the motor generator MG2.

  Further, the present invention can be applied to an electric vehicle that does not include the engine 2 and runs only by electric power, and a fuel cell vehicle that further includes a fuel cell as a power source.

  In the above, inverters 20 and 22 and motor generators MG1 and MG2 form one embodiment of the “load device” and “driving force generator” in the present invention, and positive electrode line PL3 and negative electrode line NL are the present invention. Corresponds to an example of the “power line” in FIG. In addition, power storage devices B1 and B2 correspond to one embodiment of “first power storage device” and “second power storage device” in the present invention, respectively, and converters 10 and 12 This corresponds to an example of the “voltage converter” and the “second voltage converter”.

  Further, converter control unit 32 of ECU 30 corresponds to an example of “control unit” in the present invention, and each of temperature sensors 62 and 66 corresponds to an example of “temperature detection device” in the present invention. Further, intake duct 78, cooling fan 80, and exhaust duct 82 form one embodiment of the “air cooling device” in the present invention.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 is an overall block diagram of a hybrid vehicle shown as an example of an electric vehicle equipped with a power supply system according to Embodiment 1 of the present invention. It is a schematic plan view of the hybrid vehicle for demonstrating the arrangement configuration of the converter shown in FIG. It is a circuit diagram of the converter shown in FIG. It is a functional block diagram of ECU shown in FIG. It is a detailed functional block diagram of the converter control part shown in FIG. It is the figure which showed the share ratio of the converter set by the power distribution setting part shown in FIG. It is the figure which showed the relationship between temperature and a correction value. It is the figure which showed the share ratio of the converter in the modification 1. FIG. It is the figure which showed the share ratio of the converter in the modification 2. FIG. 6 is an overall block diagram of a hybrid vehicle shown as an example of an electric vehicle equipped with a power supply system according to a second embodiment. It is the figure which showed the correction value in this Embodiment 2. FIG. It is the figure which showed the temperature and correction value of a converter.

Explanation of symbols

  2 engine, 4 power split mechanism, 6 wheels, 10, 12 converter, 20, 22 inverter, 30 ECU, 32 converter control unit, 34, 36 inverter control unit, 42, 44, 46 voltage sensor, 52, 54 current sensor, 62 Outside air temperature sensor, 64, 66 Temperature sensor, 70 Power storage pack, 72 Radiator, 74 Cooling water channel, 76 Inlet port, 78 Inlet duct, 80 Cooling fan, 82 Exhaust duct, 84 Exhaust port, 100 Hybrid vehicle, 102 Power distribution setting Part, 104 target value setting part, 106-1 signal generation part, 108-1, 108-2, 112-1, 112-2 subtraction part, 110-1, 110-2 non-results control part, 114-1, 114-2 Modulation unit, B1, B2 power storage device, C capacitor, MG1, MG2 Motor generator , PL1 to PL3 positive line, NL negative line, Q1, Q2 transistors, D1, D2 diode, CL coils, FR, FL wheel, RR, RL rear wheel.

Claims (6)

A power supply system capable of transferring power to and from a load device,
A power line for transferring power between the power supply system and the load device;
Chargeable and dischargeable first and second power storage devices;
A water-cooled first voltage conversion device provided corresponding to the first power storage device and configured to be capable of voltage conversion between the first power storage device and the power line;
An air-cooled second voltage converter configured to correspond to the second power storage device and configured to be capable of voltage conversion between the second power storage device and the power line;
When the required power for the power supply system is less than or equal to a reference value, the first and second voltage converters share a ratio of the required power that is borne by the first voltage converter so that the first and second voltage converters When the second voltage conversion device is controlled and the required power exceeds the reference value, the first voltage and the second voltage are increased so that the sharing ratio of the second voltage conversion device increases as the required power increases. A power supply system comprising a control device that controls the conversion device.   The power supply system according to claim 1, wherein the reference value is a maximum power value at which the first voltage converter can be energized.   The power supply system according to claim 1, wherein the control device stops the second voltage conversion device when the required power is equal to or less than the reference value. A temperature detecting device for detecting the temperature of the cooling air supplied to the second voltage converter;
4. The control device according to claim 1, wherein the control device controls the first voltage conversion device and the second voltage conversion device so that a sharing ratio of the second voltage conversion device increases in accordance with a decrease in the temperature. 5. The power supply system according to claim 1. A temperature detection device for detecting the temperature of the second voltage conversion device;
4. The control device according to claim 1, wherein the control device controls the first voltage conversion device and the second voltage conversion device so that a sharing ratio of the second voltage conversion device increases in accordance with a decrease in the temperature. 5. The power supply system according to claim 1. The power supply system according to any one of claims 1 to 5,
A driving force generator that receives power from the power supply system and generates a driving force of the vehicle;
A radiator that cools the refrigerant of the first voltage converter included in the power supply system;
An air cooling device for air-cooling the second voltage conversion device included in the power supply system,
The radiator is disposed at the front of the vehicle,
The first voltage converter is disposed in front of the vehicle,
The second voltage conversion device and the air-cooling device are electrically powered vehicles disposed at the rear of the vehicle.

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