阅读说明：本技术 电动车辆的电源电路 (Power supply circuit for electric vehicle ) 是由 杉本和大 于 2020-09-04 设计创作，主要内容包括：本发明涉及电动车辆的电源电路。根据本发明的电动车辆的电源电路安装在电动车辆上,该电动车辆包括：电池,其被配置为从外部DC电源接收电力；附件,其被配置为以电池的系统电压操作；以及,DC入口,从外部DC电源向其施加高于系统电压的电压。电源电路包括第一电力线、降压转换器和第二电力线。第一电力线被配置为连接DC入口和电池。降压转换器被布置在第一电力线上,并且被配置为降低从DC入口向电池供应的电压。第二电力线的一端在降压转换器与电池之间连接到第一电力线,并且另一端连接到附件。(The present invention relates to a power supply circuit for an electric vehicle. A power supply circuit of an electric vehicle according to the present invention is mounted on an electric vehicle including: a battery configured to receive power from an external DC power source; an accessory configured to operate at a system voltage of a battery; and a DC inlet to which a voltage higher than the system voltage is applied from an external DC power supply. The power supply circuit includes a first power line, a buck converter, and a second power line. The first power line is configured to connect the DC inlet and the battery. The buck converter is disposed on the first power line and is configured to reduce a voltage supplied from the DC inlet to the battery. One end of the second power line is connected to the first power line between the buck converter and the battery, and the other end is connected to the accessory.)

1. A power supply circuit mounted on an electric vehicle, the electric vehicle comprising: a battery configured to receive power from an external DC power source; an accessory configured to operate at a system voltage of the battery; and a DC inlet to which a voltage higher than the system voltage is applied from the external DC power supply, the power supply circuit including:

a first power line configured to connect the DC inlet and the battery;

a buck converter disposed on the first power line and configured to reduce a voltage supplied from the DC inlet to the battery; and

a second power line having one end connected to the first power line between the buck converter and the battery and the other end connected to the accessory.

2. The power supply circuit of claim 1, wherein:

the electric vehicle further includes a motor configured to drive the electric vehicle and a power control unit configured to drive the motor;

the step-down converter is configured as a step-up/step-down converter that additionally includes a function of raising a voltage supplied from the battery;

the power supply circuit further includes a third power line configured to connect the battery and the power control unit; and

the third power line branches from the first power line between the DC inlet and the boost/buck converter.

3. The power supply circuit of claim 2, further comprising: a DC relay arranged on the first power line between the DC inlet and the step-up/down converter and configured to switch between supply and stop of power,

wherein the third power line branches from the first power line between the DC relay and the step-up/down converter.

Technical Field

The present invention relates to a power supply circuit of an electric vehicle, and more particularly to a power supply circuit compatible with quick charging using an external DC power supply.

Background

For example, JP 2015-201915A discloses a vehicle equipped with an external connection portion (AC inlet) connected to an AC power supply outside the vehicle and a battery. In the vehicle, a DC/DC converter is disposed on a power line connecting an AC inlet and a battery.

Disclosure of Invention

In an electric vehicle equipped with a battery configured to receive electric power from an external DC power source, there are the following problems with the installation of accessories configured to operate at the system voltage of the battery.

More specifically, when the battery is rapidly charged by increasing the voltage applied to the DC inlet from the external DC power supply to above the system voltage, it is necessary to be able to protect the accessories from the high voltage while reducing the cost increase due to the high voltage measure.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a power supply circuit of an electric vehicle, which can protect an accessory configured to operate at a system voltage of a battery from a high voltage when a rapid charge is performed at the high voltage, and can also reduce an increase in cost due to a high voltage measure.

A power supply circuit of an electric vehicle according to the present invention is mounted on an electric vehicle including: a battery configured to receive power from an external DC power source; an accessory configured to operate at a system voltage of a battery; and a DC inlet to which a voltage higher than the system voltage is applied from an external DC power supply. The power supply circuit includes a first power line, a buck converter, and a second power line. The first power line is configured to connect the DC inlet and the battery. The buck converter is disposed on the first power line and is configured to reduce a voltage supplied from the DC inlet to the battery. One end of the second power line is connected to the first power line between the buck converter and the battery, and the other end is connected to the accessory.

The electric vehicle may further include a motor configured to drive the electric vehicle and a power control unit configured to drive the motor. The buck converter may also be configured as a step-up/down converter that additionally includes a function of boosting the voltage supplied from the battery. The power supply circuit may further include a third power line configured to connect the battery and the power control unit. The third power line may further branch from the first power line between the DC inlet and the boost/buck converter.

The power supply circuit may include a DC relay that is arranged on the first power line between the DC inlet and the step-up/down converter, and is configured to switch between supply and stop of the power. The third power line may also branch from the first power line between the DC relay and the step-up/down converter.

According to the power supply circuit of an electric vehicle of the present invention, the second power line for connecting the accessory to the battery is branched from the first power line between the buck converter and the battery. Therefore, even if a voltage higher than the system voltage of the battery is applied to the DC outlet, it is possible to avoid applying a high voltage to the accessory. Therefore, when the rapid charging is performed at a high voltage, it becomes possible to protect the accessory configured to operate at the system voltage from the high voltage, and also to reduce the cost increase due to the high voltage measure.

Drawings

Fig. 1 is a block diagram schematically showing the configuration of a power supply circuit included in an electric vehicle according to a first embodiment of the invention;

fig. 2 is a block diagram schematically showing a configuration of a power supply circuit according to a comparative example; and

fig. 3 is a block diagram schematically showing the configuration of a power supply circuit of an electric vehicle according to a second embodiment of the invention.

Detailed Description

In the following embodiments of the present invention, the same components in the drawings are denoted by the same reference numerals, and redundant description thereof is omitted or simplified. Further, it should be understood that even if the number, amount, range, or other numerical property of the elements is mentioned in the description of the embodiments below, the present invention is not limited to the numerical property unless it is explicitly stated otherwise or unless it is theoretically explicitly specified by the numerical property. Further, unless explicitly stated otherwise, or unless the invention is clearly theoretically specified by a structure, a step, or the like, the structure, the step, or the like described in connection with the following embodiments is not necessarily essential to the invention.

1. First embodiment

A first embodiment according to the present invention will be described with reference to fig. 1 to 2.

1-1. configuration of power supply circuit

Fig. 1 is a block diagram schematically showing the configuration of a power supply circuit 30 included in an electric vehicle 10 according to a first embodiment. An electric vehicle (hereinafter, simply referred to as "vehicle") 10 includes a Motor Generator (MG)12 and a Power Control Unit (PCU) 14. As an example, the MG 12 is of an AC (alternating current) type, and is configured to drive the vehicle 10. The PCU 14 is configured to drive the MG 12. The MG 12 corresponds to an example of "a motor" according to the present invention.

The vehicle 10 further includes a battery 16, accessories 18 and 20, and a DC (direct current) inlet 22. The battery 16 receives electric power from an external DC power supply (charging facility) outside the vehicle 10. More specifically, the battery 16 is generally configured as a battery system including a plurality of battery modules (i.e., modules made up of a plurality of battery cells connected to each other) and an electronic control unit (battery ECU). The battery ECU measures, for example, the voltage, current, and temperature of each battery module, and monitors the temperature and state of charge (SOC) of the battery system. As an example, the system voltage Vb (nominal value) of the battery 16 is 400V.

The accessories 18 and 20 are configured to operate at the system voltage Vb. Examples of the accessories 18 are an alternating current charger (AC charger) and a DC/DC converter. The AC charger (AC charging circuit) converts AC power supplied from an external AC power supply via an AC inlet (not shown) into DC power. The DC/DC converter converts a direct-current voltage output from the AC charger into a desired direct-current voltage. Further, examples of the accessories 20 are a compressor for an air conditioner in a passenger compartment of the vehicle 10 and a heater for heating water. The water mentioned here is used for heating the passenger compartment. It should be noted that the "accessory" according to the present invention is not limited to the above example as long as it is configured to operate at the system voltage Vb, and any one or more accessories may be used.

The DC inlet 22 is configured to be connectable to the above-mentioned external DC power source via a cable and a connector, not shown. A voltage (hereinafter, referred to as "supply voltage Vs") higher than the system voltage Vb of the battery 16 is applied from an external DC power supply to the DC inlet 22. An example of the supply voltage Vs is 800V.

In addition, the system voltage Vb and the supply voltage Vs are not limited to the above-described examples of 400V and 800V as long as the supply voltage Vs is higher than the system voltage Vb. Further, the system voltage Vb is determined according to the vehicle class, for example, and a value other than 400V, for example, in the range of 350 to 400V is used as the system voltage Vb. Another example of the supply voltage Vs is 900V.

The power supply circuit 30 is mounted on the vehicle 10. The power supply circuit 30 includes a first power line 32, a second power line 34, and a third power line 36, which are a pair of positive and negative power lines, respectively, and further includes a step-down converter 38 and a DC (direct current) relay 40.

The first power line 32 is configured to connect the DC inlet 22 and the battery 16. The buck converter 38 is arranged on the first power line 32. The step-down converter 38 is a step-down DC/DC converter configured to reduce the voltage (supply voltage Vs) supplied from the DC inlet 22 to the battery 16. In more detail, in an example where the system voltage Vb is 400V and the supply voltage Vs is 800V, the buck converter 38 steps down the voltage from 800V to 400V. In the vehicle 10 equipped with the battery 16 having the system voltage Vb of 400V, the use of such a step-down converter 38 allows the battery 16 to be charged while supplying a high current to the battery 16 using a fast charge of 350kW class at a high supply voltage Vs such as 800V.

The second power line 34 is configured to connect the battery 16 and the accessories 18 and 20. In the present embodiment, as shown in fig. 1, the second power line 34 branches from the first power line 32 at a branch point 42 between the buck converter 38 and the battery 16. That is, one end of the second power line 34 is connected to the first power line 32 at the branch point 42, and the other end thereof is connected to the accessories 18 and 20. More specifically, in the example shown in fig. 1, the second power line 34 branches at a branch point 44 in a bifurcated manner, and is connected to each of the accessories 18 and 20.

The DC relay 40 is arranged on the first power line 32 on a side closer to the DC inlet 22 than the branch point 42 to switch between supply and stop of electric power between the DC inlet 22 and the battery 16. In the example shown in fig. 1, a DC relay 40 is arranged between the buck converter 38 and the branch point 42. In more detail, the vehicle 10 includes an Electronic Control Unit (ECU)50 for controlling the vehicle 10, and the DC relay 40 is controlled by a command from the ECU 50 to switch between the supply and the stop of the electric power.

The third power line 36 is configured to connect the battery 16 and the PCU 14 so as to supply power to the MG 12 from the battery 16. In the example shown in fig. 1, the third power line 36 is connected to the second power line 34 at a branch point 44. That is, in this example, the third power line 36 shares a portion from the branch point 42 to the branch point 44 with the second power line 34.

The PCU 14 converts DC power of the battery 16 into AC power and supplies it to the MG 12. The PCU 14 controls the MG 12 based on a command from the ECU 50.

In addition, in the example shown in fig. 1, the power supply circuit 30 is configured as a high-voltage unit integrally including a DC relay 40 and a buck converter 38. In fig. 1, the high voltage unit is a part surrounded by a dotted frame. Furthermore, the high voltage unit also integrally includes a function of branching off a second power line 34 from the first power line 32, the second power line 34 being arranged to connect the accessories 18 and 20 to the battery 16. Furthermore, in the example shown in fig. 1, inside the high voltage unit, an accessory 18 is also included. However, like the accessory 20, the accessory 18 may be arranged outside the high voltage unit.

1-2. Effect

Fig. 2 is a block diagram schematically showing the configuration of a power supply circuit 100 according to a comparative example. The effect of the power supply circuit 30 according to the first embodiment will be described in comparison with the power supply circuit 100 according to the comparative example.

First, in the comparative example shown in fig. 2, the second power line 102 for connecting the accessories 18 and 20 with the battery 16 is branched from the first power line 32 between the DC inlet 22 and the step-down converter 38. As a result, when a high supply voltage Vs, such as 800V, is applied to the DC inlet 22, the supply voltage Vs, which is higher than the system voltage Vb, is applied to the accessories 18 and 20. Therefore, it is necessary to take measures for the accessories 18 and 20 to withstand a high voltage, or to take measures to change the circuit configuration of the power supply circuit 100. Such high voltage measures will lead to increased costs.

In contrast to the above, according to the power supply circuit 30 in the first embodiment, the second power line 34 for connecting the accessories 18 and 20 with the battery 16 is branched from the first power line 32 between the step-down converter 38 and the battery 16. Therefore, even if the supply voltage Vs higher than the system voltage Vb is applied to the DC input port 22, it is possible to avoid applying a high voltage to the accessories 18 and 20. Therefore, when the rapid charging is performed at the high supply voltage Vs, the power supply circuit 30 makes it possible to protect the accessories 18 and 20 operating at the system voltage Vb from the high voltage while reducing the increase in cost due to the high voltage measures.

2. Second embodiment

Next, a second embodiment according to the present invention will be described with reference to fig. 3.

2-1. configuration of power supply circuit

Fig. 3 is a block diagram schematically showing the configuration of a power supply circuit 70 of an electric vehicle 60 according to the second embodiment. The power supply circuit 70 according to the present embodiment is configured similarly to the power supply circuit 30 according to the first embodiment except for the following points.

The power supply circuit 70 includes a step-up/down converter 72. The step-up/down converter 72 is configured to have a step-up function for increasing the voltage supplied from the battery 16 in addition to a step-down function for reducing the voltage supplied from the DC inlet 22 to the battery 16, similar to the step-down converter 38 (see fig. 1). When the system voltage Vb (400V) of the battery 16 is equal to its input voltage, the step-up/down converter 72 steps up the voltage from 400V to 800V. Similar to the first embodiment, the accessories 18 and 20 are disposed on the first power line 32 between the step-up/down converter 72 and the battery 16.

Then, in the power supply circuit 70, unlike the power supply circuit 30, a third power line 74 configured to connect the battery 16 and the PCU 14 branches from the first power line 32 between the DC inlet 22 and the step-up/down converter 72. In more detail, in the example shown in fig. 3, unlike the power supply circuit 30, the DC relay 40 is arranged on the first power line 32 between the DC inlet 22 and the step-up/down converter 72. In other words, the step-up/down converter 72 is disposed on the first power line 32 between the DC relay 40 and the branch point 42. Further, a third power line 74 branches from the first power line 32 between the DC relay 40 and the step-up/down converter 72.

2-2. Effect

According to the power supply circuit 70 of the presently described second embodiment, during rapid charging using the high supply voltage Vs (800V) of the external DC power supply, the voltage supplied to the battery 16 is reduced from 800V to 400V by the step-up/down converter 72. Therefore, similarly to the power supply circuit 30 of the first embodiment, it is possible to avoid applying a high voltage to the accessories 18 and 20 during rapid charging.

Further, according to the power supply circuit 70 of the second embodiment, during running of the vehicle in which the MG 12 is driven using electric power of the battery 16 (during power running), the following effects 1 to 3 can be achieved.

First, a third power line 74 connected to the PCU 14 is located between the DC inlet 22 and the step-up/down converter 72. More specifically, in the example shown in fig. 3, the third power line 74 is connected between the DC relay 40 and the step-up/down converter 72. Therefore, when the vehicle is running (when the vehicle is powered), unlike the power supply circuit 30 (see fig. 1), the high voltage (800V) that has been boosted by the step-up/down converter 72 can be used for driving the MG 12 (i.e., effect 1 is achieved). In addition, in the example of the power supply circuit 30 according to the first embodiment, in order to make a high voltage such as 800V available for driving the MG 12, it is necessary to separately arrange a boost converter on the third power line 36. In contrast, according to the circuit configuration of the power supply circuit 70, it becomes possible to drive the MG 12 using a high voltage while avoiding complication of the circuit configuration due to separately adding such a boost converter and reducing cost increase.

Then, according to the circuit configuration of the comparative example shown in fig. 2, if the step-up/down converter 72 is disposed at the position of the step-down converter 38 instead of the step-down converter 38, a high voltage can be applied to the PCU 14. However, it is also possible to apply a high voltage to the accessories 18 and 20 unnecessarily. In contrast, according to the power supply circuit 70, the accessories 18 and 20 are arranged on the side closer to the battery 16 than the step-up/down converter 72, and the third power line 74 is arranged on the side closer to the DC inlet 22 than the step-up/down converter 72. Therefore, when the vehicle is running (when the vehicle is powered), it becomes possible to drive the MG 12 using the boosted high voltage (800V) while preventing the high voltage from being applied to the accessories 18 and 20 (i.e., effect 2 is achieved).

Then, according to the power supply circuit 70, the DC relay 40 is arranged between the step-up/down converter 72 and the DC inlet 22 (relay arrangement example 1). Unlike this relay arrangement example 1, the DC relay 40 may be arranged on a side closer to the battery 16 than the connection position of the third power line 74 to the first power line 32 (relay arrangement example 2). Even in this relay arrangement example 2, the above-described effects 1 and 2 can be achieved. However, in relay arrangement example 2, when electric power is supplied from the battery 16 to the PCU 14, electric power consumption occurs due to conduction (closing) of the DC relay 40. In contrast, according to the power supply circuit 70 employing the relay arrangement example 1, the DC relay 40 can be maintained in a non-conductive (open) state during vehicle running (during power running). Therefore, it becomes possible to use the high power after the step-up while reducing the power consumption of the DC relay 40 (i.e., effect 3 is achieved).