JP2020018078A - Power supply system for electric vehicle - Google Patents

Abstract

To provide a power supply system for an electric vehicle capable of reducing charging time, capable of charging from a plurality types of external power sources with different voltages, and obviating the need of re-designing power load of the vehicle.SOLUTION: A power supply system for an electric vehicle is provided with: a vehicle power load group 20 receiving a power supply from a main battery 10, including a motor 21; a voltage converter 30 bidirectionally performing a step-up operation and a step-down operation; a power supply part 60 for supplying power from a power supply source 200 to the main battery 10; and a controller 31 for controlling an operation of the voltage converter 30. The power supply part 60 is provided with: a first charging terminal 61 connected between the voltage converter 30 and the vehicle power load group 20; and a second charging terminal 62 connected between the main battery 10 and the voltage converter 30. The controller 31 controls a step-up operation and a step-down operation of the power converter 30 in response to a charging state of the power supply part 60 and an operation request state of the vehicle power load group 20 when charging the main battery 10.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a power supply system for an electric vehicle.

Conventionally, an EV system which operates a chopper (a voltage converter) as a step-down chopper or a step-up chopper to cope with a difference in a rated voltage of a motor, a maximum voltage of a battery, and an external power supply voltage is known. (For example, see Patent Document 1).
This conventional EV system describes that the power supplied from an external power supply is boosted by a chopper to charge a battery.

JP-A-2006-1962

By the way, the battery capacity of an electric vehicle tends to increase due to an increase in the cruising distance. However, if the battery capacity is simply increased, the time until full charge becomes longer. Therefore, an increase in the maximum voltage of the battery is being studied to shorten the charging time.
When the maximum battery voltage is increased, the above-described conventional EV system can charge by increasing the voltage from an existing external power supply, but has the following problems.

When an external power source of a new standard is installed so as to be able to cope with the increased battery maximum voltage, it is difficult for the conventional EV system to support charging from a plurality of types of external power sources having different voltage values.
Furthermore, when the maximum battery voltage is increased, redesign such as strengthening of the withstand voltage of the vehicle electric power load is required in accordance with the increased voltage, which causes a problem of an increase in cost and deterioration of power consumption.

  The present invention has been made in view of the above problems, and can reduce charging time, can respond to charging from a plurality of types of external power supplies having different voltage values, and can further reduce the vehicle power load. It is an object of the present invention to provide a power supply system for an electric vehicle that does not require redesign.

In order to achieve the above object, a power supply system for an electric vehicle according to the present disclosure includes:
A voltage converter that is connected between the main battery and the vehicle power load and that performs bidirectional step-up operation and step-down operation;
A power supply unit connected to a power supply source external to the electric vehicle to supply power to the main battery,
Is provided.
The power supply unit includes a first charging terminal connected between the voltage converter and the vehicle power load, and a second charging terminal connected between the main battery and the voltage converter. ,
The control unit that controls the operation of the voltage converter, when charging the main battery, according to the state of charge of the power supply unit and the operation request state of the vehicle power load, the boost operation of the voltage converter and Controls the step-down operation.

  The power supply system for an electric vehicle according to the present disclosure can directly charge the main battery from a high-voltage external power supply via the second charging terminal, thereby shortening the charging time. Also, at the time of charging from an external power supply having a voltage lower than that of the main battery, the voltage converter can be stepped up and charged from the first charging terminal. Thus, it is possible to cope with charging from a plurality of types of external power supplies having different voltage values. Then, when power is supplied from the main battery to the vehicle power load, the voltage converter is stepped down to eliminate the need to redesign the vehicle power load according to the maximum voltage of the main battery.

1 is an overall schematic diagram of a power supply system for an electric vehicle according to a first embodiment. FIG. 3 is an operation explanatory diagram when power is transmitted from the main battery 10 to the vehicle power load group 20 via the voltage converter 30 in the power supply system for the electric vehicle according to the first embodiment. FIG. 4 is an operation explanatory diagram of the power supply system of the electric vehicle according to the first embodiment at the time of charging by a first quick charger 210; FIG. 4 is an explanatory diagram of an operation at the time of charging by a second quick charger 220 in the power supply system of the electric vehicle according to the first embodiment. FIG. 4 is an operation explanatory diagram when power is supplied to an external power load 250 outside the vehicle connected to a first charging terminal 61 in the power supply system of the electric vehicle according to the first embodiment. FIG. 5 is an overall schematic diagram of a power supply system for an electric vehicle according to a second embodiment. FIG. 13 is an operation explanatory diagram at the time of transmitting power from the main battery 10 to the vehicle power load group 20 via the first voltage converter 300 in the power supply system for the electric vehicle according to the second embodiment. FIG. 10 is an explanatory diagram of an operation at the time of charging by a first quick charger 210 in a power supply system for an electric vehicle according to a second embodiment. FIG. 14 is an operation explanatory diagram of a situation in which the second voltage converter 400 operates in the power supply system of the electric vehicle according to the second embodiment, illustrating a time of power transmission from the AC power supply 230 via the normal charger 70. FIG. 14 is an operation explanatory diagram of a state where the second voltage converter 400 operates in the power supply system of the electric vehicle according to the second embodiment, showing a power transmission state in a standby state. FIG. 13 is an overall schematic diagram illustrating a power supply system of an electric vehicle according to a third embodiment. FIG. 14 is a characteristic diagram illustrating a relationship between output power and efficiency of a first voltage converter 300 and a relationship between output power and loss in a power supply system for an electric vehicle according to a fourth embodiment. FIG. 15 is a characteristic diagram illustrating a relationship between output power and efficiency of a second voltage converter 400c and a relationship between output power and loss in a power supply system for an electric vehicle according to a fourth embodiment. The output power value of second voltage converter 400c and the power output value of second voltage converter 400c when the total value of the output power of first and second voltage converters 300c and 400c in the power supply system of the electric vehicle according to the fourth embodiment is DkW + dkW = P1. FIG. 9 is a characteristic diagram showing a relationship between total losses generated in the first and second voltage converters 300c and 400c. FIG. 14 is an operation explanatory diagram showing an operation example when the output power value Pa transmitted via any one of the first and second voltage converters 300c and 400c in the power supply system for the electric vehicle according to the fourth embodiment is P1 <Pa. is there. FIG. 15 is an overall schematic diagram illustrating a power supply system of an electric vehicle according to a fifth embodiment. FIG. 15 is an operation explanatory diagram showing an example of switching control by a control unit 840 in the power supply system of the electric vehicle according to the fifth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
A power supply system for an electric vehicle according to a first embodiment will be described based on FIGS. 1, 2A, 2B, 2C, and 2D. FIG. 1 is a schematic diagram of the entire power supply system of the electric vehicle according to the first embodiment. 2A to 2D are explanatory diagrams of the operation of the power supply system of the electric vehicle according to the first embodiment.

  As shown in FIG. 1, the power supply system for an electric vehicle according to the first embodiment is a system that is mounted on the electric vehicle MV and charges the main battery 10 and supplies power to the vehicle power load group 20. It includes a converter 30, an inverter 40, and a converter 50.

The vehicle power load group 20 includes a motor 21, a sub-battery 22, an auxiliary group 23, an inverter 40, and a converter 50.
Here, the rated voltages of the electric motor 21, the inverter 40, and the converter 50 are different from those of the sub-battery 22 and the auxiliary machine group 23.

In the first embodiment, the rated voltage of the electric motor 21, the inverter 40, and the converter 50 is the first high voltage V1 (for example, about 400 V), which corresponds to the load of the first high voltage.
On the other hand, the accessory group 23 including the sub-battery 22 is a low-voltage load, and has a rated voltage of an accessory voltage Vlow (for example, about 12 V) lower than the first high voltage V1. The accessory group 23 is, for example, an air conditioner (not shown), a lighting device, and other well-known in-vehicle devices.
The main battery 10 is a battery having a second high voltage V2 (for example, about 800 V) higher than the first high voltage V1 as a maximum charging voltage.

  Voltage converter 30 is interposed in power supply circuit 100 from main battery 10 to vehicle power load group 20. In the power supply circuit 100, the inverter 40 connected to the electric motor 21 and the converter 50 connected to the sub-battery 22 and the auxiliary machine group 23 are connected in parallel to the voltage converter 30.

  The voltage converter 30 performs a boost operation and a step-down operation in two directions. Specifically, voltage converter 30 performs a step-down operation when power is supplied from main battery 10 and a second charging terminal 62 described later to vehicle power load group 20 side. Further, voltage converter 30 performs a boosting operation when power is supplied to main battery 10 from vehicle power load group 20 and first and third charging terminals 61 and 63 described later. The bidirectional step-up operation and step-down operation are controlled by the internal control unit 31, and the details will be described later.

Furthermore, the power supply system of the electric vehicle according to the first embodiment includes a power supply unit 60 for connecting to external power supply source 200 when charging main battery 10 and sub-battery 22.
The power supply unit 60 includes a first charging terminal 61, a second charging terminal 62, and a third charging terminal 63.

Further, a first quick charger 210, a second quick charger 220, and an AC power supply 230 are provided as external power supply sources connected to the power supply unit 60. In the figure, all of the first quick charger 210, the second quick charger 220, and the AC power supply 230 are shown, but when they are connected, they are selectively connected to any of them.
The first quick charger 210 is provided as a so-called infrastructure (infrastructure) and supplies electric power with the above-mentioned first high voltage V1 as a maximum output voltage. Then, the charging can be performed more rapidly than the charging by the AC power supply 230 described later.
The second quick charger 220 is also provided as a so-called infrastructure and supplies electric power with the above-mentioned second high voltage V2 as a maximum output voltage. Therefore, quick charging can be performed more than the first quick charger 210.

  The AC power supply 230 is a charging power supply provided in the home, and supplies power with a third high voltage V3 (for example, about 200 V) lower than the first high voltage V1.

  The first charging terminal 61 is for connection with the first quick charger 210, and is connected between the voltage converter 30 and the inverter 40 and the electric motor 21 in the power supply circuit 100 via the first charging circuit 110. It is connected.

  The second charging terminal 62 is for connection with the second quick charger 220, and is connected between the main battery 10 and the voltage converter 30 in the power supply circuit 100 via the second charging circuit 120. ing.

  The third charging terminal 63 is for connection to the AC power supply 230, and is connected in parallel with the first charging circuit 110 in the power supply circuit 100 via the third charging circuit 130, and the voltage converter 30 and the inverter 40 and It is connected between the motor 21. The third charging circuit 130 includes a normal charger 70. The ordinary charger 70 converts the AC third high voltage V3 supplied from the AC power supply 230 into a DC first high voltage V1.

Next, the voltage converter 30 will be described.
The voltage converter 30 performs bidirectional power conversion between the main battery 10 and the electric motor 21 as described above, and its operation is controlled by the internal control unit 31.

The control unit 31 detects the voltage and current of the power supply circuit 100, the supply state of the power supply unit 60 (from which of the charging terminals 61 to 63 power is supplied), and the detection of the operation request state of the auxiliary machine group 23. Controlled.
Hereinafter, the control by the control unit 31 will be described together with the description of the step-up and step-down operations of the voltage converter 30.

FIG. 2A shows a state at the time of electric power transmission from the main battery 10 to the vehicle electric power load group 20 via the voltage converter 30 such as at the time of running, by an arrow I2a.
In this case, the control unit 31 supplies power in response to an operation request of the electric motor 21 and the auxiliary machine group 23 which are vehicle electric power loads. Then, at this time, the voltage converter 30 performs a step-down operation from the second high voltage V2 to the first high voltage V1.

  At this time, the inverter 40 converts DC power supplied from the main battery 10 via the voltage converter 30 into AC. Further, converter 50 performs a step-down operation from first high voltage V1 to auxiliary device voltage Vlow.

FIG. 2B shows an electric power transmission state at the time of charging by the first quick charger 210 by an arrow I2b.
In this case, the control unit 31 charges the power supplied from the first quick charger 210 to the main battery 10 from the first charging circuit 110 via the power supply circuit 100 in response to charging from the first charging terminal 61. I do.

  At this time, the control unit 31 causes the voltage converter 30 to perform a boosting operation from the first high voltage V1 to the second high voltage V2, and changes the voltage of the first quick charger 210 (maximum voltage = first high voltage V1). Since the voltage is converted so as to be equal to or higher than the voltage of the main battery 10, charging is possible without voltage mismatch. At the same time, converter 50 drops the voltage from first high voltage V1, which is the rated voltage, to accessory voltage Vlow. In this case, since the rated voltage of converter 50 is equal to the rated voltage of first quick charger 210, there is no problem even if the voltage of first quick charger 210 is applied.

  Although not shown, even when charging from the AC power supply 230, the control unit 31 causes the voltage converter 30 to perform a boosting operation from the first high voltage V1 to the second high voltage V2 in the same manner as described above. . Thus, since the voltage from the ordinary charger 70 (= the first high voltage V1) is converted to be equal to or higher than the voltage of the main battery 10, charging can be performed without voltage mismatch.

  FIG. 2C shows the power transmission state at the time of charging by the second quick charger 220 by an arrow I2c. Since the output voltage of the second quick charger 220 is equal to the maximum voltage of the main battery 10, the main battery 10 can be charged directly without passing through the voltage converter 30. At this time, if there is an operation request from sub-battery 22 and accessory group 23, control unit 31 causes voltage converter 30 to perform a step-down operation, stepping down from second high voltage V2 to first high voltage V1 or lower, and Power is transmitted to 50.

  Note that converter 50 drops the voltage from first high voltage V1, which is the rated voltage, to auxiliary equipment voltage Vlow. The operation request in this case includes, for example, a request for operating the air conditioner at the time of charging, and a request for charging due to a decrease in the voltage of the sub-battery 22.

FIG. 2D shows the power transmission state when power is supplied to the external power load 250 outside the vehicle connected to the first charging terminal 61 by an arrow I2d.
In this case, control unit 31 causes voltage converter 30 to perform a step-down operation in accordance with connection of external power load 250 to first charging terminal 61, and sets the voltage of main battery 10 to a voltage suitable for external power load 250. Step down operation. Further, converter 50 reduces the voltage stepped down by voltage converter 30 to accessory voltage Vlow.

  In this case, basically, the voltage suitable for the external power load 250 is the first high voltage V1. As such an external power load 250, for example, the first high voltage V1 is the rated voltage. There is a DC / AC converter for supplying AC power for home use. Alternatively, the external power load 250 may be a stationary storage battery or a battery mounted on another electric vehicle. Further, a sensor for detecting an appropriate voltage for the external power load 250 connected to the first charging terminal 61 may be provided, and the voltage may be reduced to a voltage corresponding to the detection.

(Effect of Embodiment 1)
Hereinafter, effects of the power supply system for the electric vehicle according to the first embodiment will be enumerated.
(1) The power supply system of the electric vehicle according to the first embodiment includes:
A main battery 10 for supplying electric power to the electric vehicle MV,
A vehicle power load group 20 including an electric motor 21 supplied with electric power from the main battery 10;
A voltage converter 30 that is connected between the main battery 10 and the vehicle power load and that performs a bidirectional step-up operation and step-down operation;
A power supply unit 60 connected to a power supply source 200 external to the electric vehicle MV to supply power from the power supply source 200 to the main battery 10;
A control unit 31 for controlling the operation of the voltage converter 30,
With
The power supply unit 60 includes a first charging terminal 61 connected between the voltage converter 30 and the vehicle power load group 20, and a second charging terminal 62 connected between the main battery 10 and the voltage converter 30. And
Control unit 31 controls the boosting operation and the step-down operation of voltage converter 30 according to the charging state of power supply unit 60 and the operation request state of vehicle power load group 20 when charging main battery 10.
Therefore, the main battery 10 can be charged directly from the second quick charger 220 as the high-voltage external power supply source 200, and the charging time can be reduced. Also, when charging from the first quick charger 210 and the AC power supply 230 as external power supplies having a lower voltage than the main battery 10, the voltage converter 30 can be charged by performing a step-up operation. Therefore, it is possible to handle charging from a plurality of types of external power supply sources 200 having different voltage values. When power is supplied from the main battery 10 to the vehicle power load group 20, it is necessary to redesign the vehicle power load group 20 so as to correspond to the maximum voltage of the main battery 10 by stepping down the voltage converter 30. There is no.
As described above, the charging time can be reduced, and charging from a plurality of types of external power sources (power supply sources 200) having different voltage values can be supported. An unnecessary power supply system for an electric vehicle can be provided.

(2) The power supply system of the electric vehicle according to the first embodiment includes:
A load whose rated voltage is the first high voltage V1 including the motor 21, the inverter 40, and the converter 50 as the vehicle power load group 20 is connected to the voltage converter 30,
The main battery 10 has a second high voltage V2 higher than the first high voltage V1 as a maximum voltage,
As the vehicle power load group 20, a sub-battery 22 as a low-voltage load that is connected via a converter 50 having the first high voltage V1 as a rated voltage and operating at a voltage lower than the first high voltage V1, and an auxiliary group 23 Is included,
The control unit 31 causes the voltage converter 30 to perform a boosting operation when power is supplied from the first charging terminal 61, and when the power is directly supplied from the second charging terminal 62 to the main battery 10, the control unit 31 supplies a low voltage load. When there is an operation request, the voltage converter 30 performs a step-down operation.
Therefore, even when the second high voltage V2 is being charged from the second charging terminal 62, power can be supplied to the sub-battery 22 and the accessory group 23 as a low-voltage load.

(3) The power supply system of the electric vehicle according to the first embodiment includes:
The control unit 31 causes the voltage converter 30 to perform a step-down operation when power is not supplied to either the first charging terminal 61 or the second charging terminal 62.
Therefore, power can be supplied to the vehicle power load group 20 whose rated voltage is lower than the maximum voltage of the main battery 10 (second high voltage V2).

(4) The power supply system of the electric vehicle according to the first embodiment includes:
When an external power load 250 is connected to the first charging terminal 61, the control unit 31 performs power conversion on the voltage converter 30 according to the voltage difference between the main battery 10 and the external power load 250, and Power is supplied to the power load 250.
Therefore, even if the voltage of the main battery 10 is increased, power can be supplied to the external power load 250 whose rated voltage is lower than the second high voltage V2 which is the maximum voltage of the main battery 10.

(Other embodiments)
Hereinafter, other embodiments will be described. In the description of the other embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

(Embodiment 2)
Next, a power supply system for an electric vehicle according to a second embodiment will be described with reference to FIGS. 3, 4A, 4B, 4C, and 4D. FIG. 3 is an overall schematic diagram of the power supply system of the electric vehicle according to the second embodiment. 4A to 4D are explanatory diagrams illustrating the operation of the power supply system for the electric vehicle according to the second embodiment.

In the second embodiment, as shown in FIG. 3, a first voltage converter 300 and a second voltage converter 400 are provided in parallel as voltage converters, and the first voltage converter 300 and the second voltage converter This is an example in which a voltage converter 400 is selectively operated.
Both voltage converters 300 and 400 are capable of bidirectional voltage conversion in the same manner as voltage converter 30 of the first embodiment, and are stepped down from main battery 10 to vehicle power load group 20 to reduce the vehicle power load. The boosting is performed from the group 20 side to the main battery 10 side.

  The rated power of the second voltage converter 400 is smaller than the rated power of the first voltage converter 300. For example, it is assumed that the rated value of the electric motor 21 and the inverter 40> the rated value of the first quick charger 210> the rated value of the ordinary charger 70> the rated value of the converter 50. In such a case, for example, the rated value of the first voltage converter 300 is set to a value larger than the rated values of the electric motor 21 and the inverter 40, and the rated value of the second voltage converter 400 is Value.

  As an example of the above rated values, the rated value of the electric motor 21 and the inverter 40 is about 80 kW, the rated value of the first quick charger 210 is about 50 kW, the rated value of the ordinary charger 70 is about 6 kW, and the rating of the converter 50 is The value is about 1 kW. The rated value of the first voltage converter 300 is about 85 kW, and the rated value of the second voltage converter 400 is about 6 kW.

Next, the operation of the first and second voltage converters 300 and 400 will be described.
First, a case where the first voltage converter 300 performs a boost operation and a step-down operation will be described. That is, the first voltage converter 300 is operated when the amount of transmitted power is relatively large.
FIG. 4A shows a state at the time of power transmission from the main battery 10 to the vehicle power load group 20 via the first voltage converter 300, such as at the time of running, by an arrow I4a.

  That is, control unit 301 supplies AkW to inverter 40 and electric motor 21 in response to the operation request, and transmits AKW to sub-battery 22 and accessory group 23 via converter 50. In this case, the rated voltage (AkW) of the inverter 40 and the electric motor 21 is relatively large (for example, A = about 80 kW), and (A + a) kW is transmitted as the total power amount. Is performed by the first voltage converter 300 having a large value. The power amount akW to the auxiliary machine group 23 is, for example, about 1 kW.

  FIG. 4B shows the state at the time of power transmission during charging by the first quick charger 210 by an arrow I4b. The first quick charger 210 has a relatively large rated voltage (BkW) (for example, B = about 50 kW) and a small rated voltage of the converter 50 (for example, about AKW = 1 kW). Of the power (Ba) kW becomes a relatively large value. For this reason, the control unit 301 causes the first voltage converter 300 to perform a boosting operation. In this case, electric power is directly supplied from first quick charger 210 to sub-battery 22 and auxiliary equipment group 23 via converter 50.

Next, a situation in which the second voltage converter 400 having a relatively small rated power operates will be described with reference to FIGS. 4C and 4D.
FIG. 4C shows a state at the time of power transmission from the AC power supply 230 via the ordinary charger 70 by an arrow I4c. In this case, a relatively small amount of bkW (bkW = about 6 kW) is supplied from the AC power supply 230 as the electric energy. In this case, an electric energy of akW is transmitted to the converter 50 and an electric energy of (ba) kW (for example, ba = 5 kW) is transmitted to the main battery 10. Therefore, the control unit 401 performs the boosting operation to the main battery 10 by the second voltage converter 400 whose rated power is relatively small, and transmits the power.

FIG. 4D shows the power transmission state in the non-charging state and the standby state by an arrow I4d.
Generally, in electric vehicle MV, converter 50 operates to charge sub-battery 22 in a standby state to prevent discharge of sub-battery 22 (battery death). In this case, control unit 401 causes second voltage converter 400, whose rated power is relatively small, to perform a step-down operation in order to transmit an amount of power of about akW from main battery 10 to converter 50.

  As described above, the power value at which power is transmitted in the power supply system of the electric vehicle according to the second embodiment changes variously depending on the situation. Accurate power conversion can be performed by selectively operating the first voltage converter 300 and the second voltage converter 400 having different rated power values according to the power value to be transmitted.

Hereinafter, effects of the power supply system for the electric vehicle according to the second embodiment will be described.
(2-1) The power supply system of the electric vehicle according to the second embodiment includes:
As voltage converters, a first voltage converter 300 having a relatively large rated power and a second voltage converter 400 having a relatively small rated power are provided in parallel.
Therefore, the first voltage converter 300 is operated to transmit power when transmitting large power such as rapid charging and traveling, and the second voltage converter 400 is transmitted when transmitting small power during normal charging and standby. It can be operated to transmit power.
Accordingly, by increasing the maximum voltage of the main battery 10, when performing power transmission of a wide range of power values, the two voltage converters 300 and 400 having different rated powers are selectively used, so that power transmission can be performed with high accuracy. It can be carried out.

  Note that the effects described in (1), (2), and (3) are also achieved in the second embodiment, as in the first embodiment. Although not described, even in the second embodiment, power can be supplied by connecting to the external power load 250 via the first charging terminal 61 as in the first embodiment. In this case, by transmitting the power by causing the first voltage converter 300 having a large rated power to perform the step-down operation, the power can be transmitted accurately, and the effect described in the above (4) can be obtained. it can.

(Embodiment 3)
Next, a power supply system for an electric vehicle according to a third embodiment will be described with reference to FIG. FIG. 5 is an overall schematic diagram showing the power supply system of the electric vehicle according to the third embodiment.
The third embodiment is a modification of the second embodiment. When the voltage of the main battery 10 is lower than the first high voltage V1 during charging from the first quick charger 210, the first voltage converter 300b ( 5 (see FIG. 5).

FIG. 5 is a circuit diagram showing a circuit configuration of the first voltage converter 300b and the second voltage converter 400b.
The first voltage converter 300b is a non-insulated bidirectional buck-boost converter including a switching circuit 310 having switches 311 and 312 and diodes 313 and 314 connected in parallel to the switches 311 and 312.

  The second voltage converter 400b is a non-isolated bidirectional buck-boost converter including a switching circuit 410 having switches 411 and 412 and diodes 413 and 414 connected in parallel to the switches 411 and 412.

  Further, the forward voltages Vf1 and Vf2 of the two diodes 313 and 413 are set in a relationship of Vf1 <Vf2.

The operation of both switching circuits 310 and 410 will be described below.
The voltage of the main battery 10 may fall below the first high voltage V1 depending on the use of power. For example, when the voltage of the main battery 10 is lower than the rated voltage of the first high voltage V1 (for example, about 400 V) (for example, about 380 V), the step-up / step-down operation by both voltage converters 300b and 400b is unnecessary. .

Arrow I5 in FIG. 5 indicates the power transmission state in the third embodiment in such a case by arrow I5.
In this case, the diode 313 is preferentially energized, and the power from the first quick charger 210 is transmitted to the main battery 10 via the first voltage converter 300b. At this time, voltage conversion is not performed in the first voltage converter 300b, and only DC power is supplied.

  For example, at the start of charging, it is assumed that the voltage of the main battery 10 falls below the maximum output voltage of the first quick charger 210. At this time, the step-up operation by the first voltage converter 300b is not necessary, and the diode 313 of the first voltage converter 300b preferentially conducts electricity to perform charging. Therefore, it is possible to prevent a failure such as a failure of the second voltage converter 400b whose rated power is relatively small and a power higher than the rated power is supplied to the second voltage converter 400b.

  The configuration of the switching circuits 310 and 410 shown in the third embodiment is an example, and a control unit (not shown) that performs control based on the voltage value on the main battery 10 side and the voltage value on the inverter 40 side is provided. Alternatively, both voltage converters 300b and 400b may be selectively subjected to a boosting operation.

Hereinafter, effects of the power supply system for the electric vehicle according to the third embodiment will be described.
(3-1) The power supply system of the electric vehicle according to the third embodiment includes:
As the voltage converter, a first voltage converter 300b having a relatively large rated power and a second voltage converter 400b having a relatively small rated power are provided in parallel,
When charging from the first charging terminal 61, if the voltage of the main battery 10 is lower than the first high voltage V1 that is the voltage from the first charging terminal 61, the switching circuits 310 and 410 as control units The power transmission is performed with priority given to the one-voltage converter 300b.
As described above, when the step-up operation and the step-down operation of both voltage converters 300b and 400b are unnecessary, the first voltage converter 300b having a large rated power is preferentially energized. For this reason, it is possible to prevent the second voltage converter 400b having a small rated power from being supplied with power equal to or higher than the rated power, thereby causing a failure or the like.

(Embodiment 4)
Next, a power supply system for an electric vehicle according to a fourth embodiment will be described with reference to FIGS. 6A, 6B, 6C, and 7. FIG.
The fourth embodiment is a modification of the second embodiment, and is an example in which the voltage converters 300c and 400c (see FIG. 7) are selectively operated based on the relationship between efficiency and loss. .

  FIG. 6A shows the relationship between the output power and the efficiency of the first voltage converter 300 and the relationship between the output power and the loss. In FIG. 6A, the output power value P1 at which the value of the loss is minimized is, for example, about the same as the output power of the first quick charger 210 (for example, about 50 kW).

  FIG. 6B shows the relationship between the output power and the efficiency of the second voltage converter 400c, and the relationship between the output power and the loss. In FIG. 6B, the maximum power value P2 that can be output by the second voltage converter 400c is, for example, the output power of the AC power supply (for example, about 7 kW).

  In the fourth embodiment, when the output power value P transmitted via one of the two voltage converters 300c and 400c is P1 <P, both the first voltage converter 300c and the second voltage converter 400c are used. To work.

FIG. 7 shows an example of such an operation.
In the example illustrated in FIG. 7, as indicated by an arrow I7, the control units 301 and 401 perform control such that power is transmitted from the main battery 10 to the inverter 40 and the converter 50 via the voltage converters 300c and 400c.

  At this time, the sum of the output power values Pa of both voltage converters 300 and 400 is PbkW + PckW, and Pb + Pc = Pa> P1. In this case, the loss generated in the first voltage converter 300 can be reduced as compared with the case where power transmission of PakW (= PbkW + PckW> P1) is performed only by the first voltage converter 300c. The loss of the first voltage converter 300 is smaller than the loss caused by increasing the transmission power of the second voltage converter 400c from 0 kW to PckW. Therefore, the total loss generated in both voltage converters 300c and 400c is low.

  FIG. 6C shows the output power value PckW of the second voltage converter 400c and the total generated by the two voltage converters 300c and 400c when the total output power of the two voltage converters 300c and 400c is PakW (PbkW + PckW). It shows the relationship between losses. As shown in FIG. 6C, it can be seen that the total loss changes by operating the second voltage converter 400c, and the total loss is minimized when operating near the output power value PckW.

  However, even when the output power value P> P1 (for example, a value near P1), operating only the first voltage converter 300c without operating the second voltage converter 400 causes a loss. If it can be suppressed, the control units 301 and 401 perform power conversion only with the first voltage converter 300c.

  When the output power value P transmitted via both voltage converters 300c and 400c is P2 <P <P1, control units 301 and 401 perform power conversion only by first voltage converter 300c. Further, when output power value P <P2, control units 301 and 401 perform power conversion only with second voltage converter 400.

That is, in the fourth embodiment, control units 301 and 401 perform “only operation of first voltage converter 300c”, “only operation of second voltage converter 400c”, and “two voltage converters 300c” according to output power value P. , 400c is operated "to determine the condition that minimizes the loss. Thereby, the loss by both voltage converters 300c and 400c can be reduced.
In this combination switching control, a map, an arithmetic expression, or the like is created and stored in advance based on an experimental result, a simulation, or the like, and is controlled according to the output power value P.

Hereinafter, effects of the power supply system for the electric vehicle according to the fourth embodiment will be described.
(4-1) The power supply system of the electric vehicle according to the fourth embodiment includes:
The control units 301 and 401 control the operation of the first voltage converter 300c and the operation of the second voltage converter 400c based on the conduction loss of the first voltage converter 300c and the second voltage converter 400c.
Therefore, the loss due to both voltage converters 300c and 400c can be reduced.

(Embodiment 5)
Next, a power supply system for an electric vehicle according to a fifth embodiment will be described with reference to FIGS.
The fifth embodiment is a modification of the first embodiment. As shown in FIG. 8, first to third switches 810, 820, and 830 for switching between a conducting state and a non-conducting state are used. This is an example in which the charging path is switched according to the voltage state of the battery.

In the power supply system for an electric vehicle according to the fifth embodiment, first charging circuit 110 has bypass circuit 110 a connected to second charging circuit 120. The first charging circuit 110 is provided with a first switch 810 that switches between a conductive state and a non-conductive state between the first quick charger 210 and the voltage converter 30d.
Further, the bypass circuit 110a is provided with a second changeover switch 820 that switches between the first quick charger 210 and the main battery 10 between a conductive state and a non-conductive state.

Further, the second charging circuit 120 is provided with a third changeover switch 830 that switches between a conductive state and a non-conductive state between the second quick charger 220 and the voltage converter 30d.
Each of the changeover switches 810, 820, and 830 is, for example, a relay or a semiconductor switch that opens and closes mechanically.

  The switching between the conduction state and the non-conduction state of each of the changeover switches 810, 820, 830 is performed by the control unit 840. The control unit 840 performs switching control based on power information including the power state of the main battery 10.

An example of the switching control by the control unit 840 will be described with reference to FIG.
When the voltage of the main battery 10 falls below the maximum output voltage (V1) of the first quick charger 210 during charging by the first quick charger 210, the first switch 810 is turned off. , The second switch 820 is turned on. In this case, as shown by an arrow Id9 in FIG. 9, the main battery 10 is directly charged from the first quick charger 210, and the voltage converter 30d is set to a non-operating state. Therefore, it is possible to eliminate the power supply loss of the voltage converter 30d and suppress the loss.
At this time, when there is an operation request for a low-voltage system such as sub-battery 22 and auxiliary equipment group 23, voltage converter 30d performs only power transmission to supply power to converter 50.

Thereafter, when the voltage of the main battery 10 reaches the maximum voltage (V1) of the first quick charger 210, the control unit 840 sets the first changeover switch 810 to the conductive state, and sets the second changeover switch 820 to the non-conductive state. State.
In this case, as described with reference to FIG. 2B, voltage converter 30d performs a boosting operation to charge main battery 10.

  Note that the bypass circuit 110a, the switches 810 to 830, and the control unit 840 described in the fifth embodiment can also be applied to the second embodiment. In this case, power can be directly transmitted from the first quick charger 210 to the main battery 10 without using the configuration in which the first voltage converter 300 is preferentially energized as described in the third embodiment. Therefore, it is possible to simplify the configuration of both voltage converters 300 and 400, and to prevent a problem such as a failure from being caused by supplying power equal to or higher than the rating to second voltage converter 400.

Hereinafter, effects of the power supply system for the electric vehicle according to the fifth embodiment will be described.
(5-1) The power supply system of the electric vehicle according to the fifth embodiment includes:
A first switch 810 that switches between a conductive state and a non-conductive state between the first charging terminal 61 and the voltage converter 30d;
A second changeover switch 820 that switches between a conductive state and a non-conductive state of a bypass circuit 110a that connects the first charging terminal 61 between the main battery 10 and the voltage converter 30d;
With
When the voltage of the main battery 10 is lower than the first high voltage V1 at the time of charging from the first charging terminal 61, the control unit 31d sets the first changeover switch 810 to the non-conducting state and performs the second changeover. When the switch 820 is turned on and the voltage of the main battery 10 is higher than the first high voltage V1, the first switch 810 is turned on and the second switch 820 is turned off.
Therefore, when the boosting operation of the voltage converter 30d is unnecessary, the power can be transmitted through the bypass circuit 110a without energizing the voltage converter 30d, so that loss and deterioration caused by energizing the voltage converter 30d are suppressed. it can.
Further, when the first voltage converter 300 and the second voltage converter 400 are provided in parallel instead of the voltage converter 30d, power exceeding the rating is supplied to the second voltage converter 400, and failure such as failure may occur. Failure can be prevented. Further, in this case, there is no need to provide the switching circuits 310 and 410 described in the third embodiment, and the design conditions of the voltage converters 300 and 400 can be simplified.

  As described above, the power supply system for the electric vehicle according to the present disclosure has been described based on the embodiment. However, the specific configuration is not limited to this embodiment, and the gist of the invention according to each claim in the claims is described. Changes and additions of the design are allowed as long as they do not deviate.

For example, in the embodiments, one specific example of the value of the rated voltage is disclosed by numerical values, but these values are not limited to these.
Further, in the embodiment, the power supply unit 60 including the first to third charging terminals 61 to 63 has been described. However, the power supply unit 60 is not limited to this. It suffices if it has 61 and the second charging terminal 62.

10 Main Battery 20 Vehicle Power Load Group 21 Motor (Vehicle Power Load)
22 Sub-battery (vehicle power load: low voltage load)
23 Auxiliary group (vehicle power load: low voltage load)
Reference Signs List 30 voltage converter 30d voltage converter 31 control unit 31d control unit 40 inverter (vehicle power load)
50 converter (vehicle power load)
Reference Signs List 60 power supply unit 61 first charging terminal 62 second charging terminal 70 ordinary charger 100 power supply circuit 110 first charging circuit 110a bypass circuit 120 second charging circuit 200 power supply source 250 external power load 300 first voltage converter 300b First voltage converter 300c First voltage converter 301 Control unit 310 Switching circuit 400 Second voltage converter 400b Second voltage converter 400c Second voltage converter 401 Control unit 410 Switching circuit 810 Switch 820 Switch 830 Switch 840 control unit MV electric vehicle V1 first high voltage V2 second high voltage Vlow auxiliary equipment voltage

Claims (8)

A main battery that supplies power in the electric vehicle;
A vehicle power load including an electric motor that receives power supply from the main battery;
A voltage converter that is connected between the main battery and the vehicle power load and that performs a bidirectional boosting operation and a step-down operation;
A power supply unit connected to a power supply outside the electric vehicle to supply power from the power supply to the main battery;
A control unit for controlling the operation of the voltage converter;
With
The power supply unit includes a first charging terminal connected between the voltage converter and the vehicle power load, and a second charging terminal connected between the main battery and the voltage converter. Prepared,
The control unit is configured to control a step-up operation and a step-down operation of the voltage converter according to a state of charge of the power supply unit and an operation request state of the vehicle power load when charging the main battery. Power system. The power supply system for an electric vehicle according to claim 1,
The voltage converter is connected to a load having a first high voltage, the rated voltage including the electric motor as the vehicle power load,
The main battery has a second high voltage higher than the first high voltage as a maximum voltage,
A low-voltage load that is connected to the vehicle power load via a converter that uses the first high voltage as a rated voltage and that operates at a voltage lower than the first high voltage;
The control unit causes the voltage converter to perform a boosting operation when power is supplied from the first charging terminal, and when there is a request for operation of the low-voltage load when power is supplied from the second charging terminal. A power supply system for an electric vehicle that causes a voltage converter to perform a step-down operation. The power supply system for an electric vehicle according to claim 1 or 2,
A power supply system for an electric vehicle, wherein a first voltage converter having a relatively large rated power and a second voltage converter having a relatively small rated power are provided in parallel as the voltage converter. The power supply system for an electric vehicle according to claim 3,
The controller performs power transmission by giving priority to the first voltage converter when the voltage of the main battery is lower than the voltage from the first charging terminal during charging from the first charging terminal. Power supply system for electric vehicles. The power supply system for an electric vehicle according to claim 3 or 4,
The control unit controls an operation of the first voltage converter and an operation of the second voltage converter based on a power loss of the first voltage converter and the second voltage converter. system. The power supply system for an electric vehicle according to any one of claims 1 to 5,
The power supply system for an electric vehicle that causes the voltage converter to perform a step-down operation when power is not supplied to any of the first charging terminal and the second charging terminal. The power supply system for an electric vehicle according to any one of claims 3 to 6, wherein
A first switch that switches between a conductive state and a non-conductive state between the first charging terminal and the voltage converter;
A second switch that switches between a conductive state and a non-conductive state of a bypass circuit that connects the first charging terminal between the main battery and the voltage converter;
With
The control unit may cause the first switch to be in a non-conductive state when the voltage of the main battery is lower than the first high voltage when charging from the first charging terminal. When the changeover switch is turned on, and the voltage of the main battery is higher than the first high voltage, the first changeover switch is turned on while the second changeover switch is turned off. Vehicle power system. The power supply system for an electric vehicle according to any one of claims 3 to 7, wherein
When an external power load is connected to the first charging terminal, the control unit performs power conversion on the voltage converter according to a voltage difference between the main battery and the external power load, and A power supply system for an electric vehicle that supplies power to an electric load.