阅读说明：本技术 Dc/dc转换单元 (DC/DC conversion unit ) 是由 佐竹周二 榎本伦人 于 2019-05-31 设计创作，主要内容包括：两个DC/DC转换器(31A和31B)对向车辆的电机供给电力的驱动电池(2)的电源电压进行DC/DC转换,并且将转换的电源电压供给到作为安装于车辆的电气部件的自动操作负载(5)和一般负载(6)。控制单元(34A和34B)控制两个DC/DC转换器(31A和31B)。控制单元(34A和34B)在DC/DC转换开始时使两个DC/DC转换器(31A和31B)中的仅一个DC/DC转换器进行DC/DC转换,并且然后使两个DC/DC转换器(31A和31B)均进行DC/DC转换。(two DC/DC converters (31A and 31B) DC/DC-convert a power supply voltage of a drive battery (2) that supplies electric power to a motor of a vehicle, and supply the converted power supply voltage to an automatic operation load (5) and a general load (6) that are electrical components mounted on the vehicle. A control unit (34A and 34B) controls the two DC/DC converters (31A and 31B). The control unit (34A and 34B) causes only one of the two DC/DC converters (31A and 31B) to perform DC/DC conversion at the start of DC/DC conversion, and then causes both of the two DC/DC converters (31A and 31B) to perform DC/DC conversion.)

1. A DC/DC conversion unit comprising:

two DC/DC converters that convert a power supply voltage of a driving power supply that supplies electric power to a motor of a vehicle by DC/DC conversion, and supply the converted power supply voltage to an electric component mounted to the vehicle; and

A control unit for controlling the two DC/DC converters,

The control unit enables only one of the two DC/DC converters to perform DC/DC conversion when the DC/DC conversion is started, and then enables both of the two DC/DC converters to perform DC/DC conversion.

2. the DC/DC conversion unit of claim 1,

Wherein, among the two DC/DC converters, one DC/DC converter which starts conversion first has an output characteristic which is more efficient when the output power is low than the other DC/DC converter.

3. The DC/DC conversion unit according to claim 1 or 2,

Wherein two of the control units are provided, and

Wherein the two control units independently control the two DC/DC converters.

4. The DC/DC conversion unit according to any one of claims 1 to 3,

Wherein two power supplies for an electrical component are respectively provided between the electrical component and the outputs of the two DC/DC converters.

Technical Field

The present invention relates to a DC/DC conversion unit.

Background

In recent years, in hybrid vehicles and electric vehicles, as power sources, it has been proposed to provide a drive battery for driving a motor and a DC/DC converter for converting an output from the drive battery into voltages corresponding to various electrical components other than the drive motor.

in addition, in order to prevent the power supply to the electrical components from being lost due to a failure of the DC/DC converter or the like during the operation of the vehicle, a technique of providing two DC/DC converters has been proposed (patent document 1). In particular, this technique is an effective technique when the electrical component is involved in automatic operation.

However, there is a problem in that efficiency is reduced when conversion of two DC/DC converters is started simultaneously in a normal state.

Disclosure of Invention

Technical problem

The present invention has been made in view of the above background, and an object of the present invention is to provide a DC/DC conversion unit capable of improving efficiency.

means for solving the problems

according to a first aspect of the present invention, there is provided a DC/DC conversion unit including:

Two DC/DC converters that perform conversion of a power supply voltage of a driving power supply that supplies electric power to a motor of a vehicle by DC/DC conversion and supply the converted power supply voltage to an electrical component mounted to the vehicle; and

A control unit for controlling the two DC/DC converters,

Wherein the control unit causes only one of the two DC/DC converters to perform DC/DC conversion at the start of DC/DC conversion, and then causes both of the two DC/DC converters to perform DC/DC conversion.

Further, among the two DC/DC converters, one DC/DC converter that starts conversion first may have output characteristics that become efficient when the output power is low, as compared with the other DC/DC converter.

Further, two of the control units may be provided, and the two control units may independently control the two DC/DC converters.

Further, two power supplies for electrical components may be provided between the electrical components and the outputs of the two DC/DC converters, respectively.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above aspect, the control unit causes only one of the two DC/DC converters to perform DC/DC conversion at the start of DC/DC conversion, and then causes both of the two DC/DC converters to perform DC/DC conversion. Thus, the conversion operation of the two DC/DC converters is not performed when the output power at the start of conversion is low, and the efficiency can be improved.

Drawings

Fig. 1 is a circuit diagram showing one embodiment of a power supply apparatus including a DC/DC conversion unit of the present invention;

FIG. 2 is a circuit diagram showing further details of the power supply apparatus shown in FIG. 1;

Fig. 3 is a graph showing a relationship between output power and efficiency of each of the two DC/DC converters shown in fig. 1;

Fig. 4 is a graph showing the relationship between the efficiency of the cooperative control and the non-cooperative control of the two DC/DC converters having the characteristics shown in fig. 3 and each output power;

Fig. 5 is a graph showing a relationship between output power and efficiency of two DC/DC converters shown in fig. 1 according to another embodiment;

Fig. 6 is a graph showing the relationship between the efficiency of performing the cooperative control and not performing the cooperative control on the two DC/DC converters having the characteristics shown in fig. 5 and each output power;

Fig. 7 is a graph showing a relationship between each output power and efficiency of the two DC/DC converters shown in fig. 1 according to another embodiment; and is

Fig. 8 is a graph showing the relationship between the efficiency of performing the cooperative control and not performing the cooperative control on the two DC/DC converters having the characteristics shown in fig. 7 and each output power.

list of reference marks

2 drive battery (drive power supply)

3 DC/DC conversion unit

4A first sub-battery (Power supply for electric component)

4B second sub-battery (Power supply for electric component)

5 automatic operation load (electric component)

General load 6 (electric parts)

31A, 31B DC/DC converter

34A, 34B control unit

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to fig. 1 and 2. The power supply device 1 shown in fig. 1 is mounted on a hybrid vehicle, an electric vehicle, or the like that is driven by a motor (not shown), and supplies electric power to an automatic operation load 5 and a general load 6 as electric components.

As shown in the figure, the power supply device 1 includes a drive battery 2 as a drive power supply, a DC/DC conversion unit 3, two first sub-batteries 4A and two second sub-batteries 4B as power supplies for electrical components, an automatic operation load 5, and a general load 6.

The drive battery 2 is a main battery, and its main purpose is to drive a motor as a power source for driving a hybrid vehicle or an electric vehicle. The drive battery 2 is connected to the motor via an inverter circuit (not shown) that converts direct current into alternating current. For this reason, a high-voltage, high-capacity battery is used as the drive battery 2.

The DC/DC conversion unit 3 DC/DC-converts the power supply voltage of the high-voltage drive battery 2, and supplies to the low-voltage first sub-battery 4A, second sub-battery 4B, automatic operation load 5, and general load 6. Details of the DC/DC conversion unit 3 will be described later.

The primary purpose of the first sub-battery 4A and the second sub-battery 4B as sub-batteries is to drive electric components (the automatic operation load 5, the general load 6) other than the motor, which are driven by a low voltage. For this reason, as the first sub-battery 4A and the second sub-battery 4B, batteries having a lower voltage and a smaller capacity than the driving battery 2 are used.

In addition, the first sub-battery 4A is provided separately from the second sub-battery 4B. The first sub-battery 4A is charged with the electric power output from the DC/DC conversion unit 3, and supplies the electric power to both the automatic operation load 5 and the general load 6. The second sub-battery 4B is charged with the electric power output from the DC/DC conversion unit 3, and supplies the electric power only to the automatic operation load 5. Power is not supplied from the second sub-battery 4B to the general load 6.

The first sub-battery 4A and the second sub-battery 4B are batteries having the same output voltage. The second sub-battery 4B is an auxiliary battery for continuing to supply electric power to at least the automatic operation load 5 when a power supply abnormality such as interruption of charging from the DC/DC conversion unit 3 to the first battery 4A occurs. As a result, even if the above-described power supply abnormality occurs, the vehicle can continue the automatic operation and return to the nearest service base.

In the present embodiment, the second sub-battery 4B supplies only electric power to the automatic operation load 5, and has a smaller capacity than the first sub-battery 4A. Of course, the present invention is not limited thereto, the second sub-battery 4B may be configured to be able to supply power to both the automatic operation load 5 and the general load 6, and the capacities of the first sub-battery 4A and the second sub-battery 4B may be the same.

The automatic operation load 5 is constituted by electric components necessary for driving and controlling the automatic operation of at least one of the accelerator, the steering wheel, and the brake. The load 6 is generally constituted by electric components such as an air conditioner and a sound which do not require automatic operation.

Next, details of the DC/DC conversion unit 3 will be described. The DC/DC conversion unit 3 includes: two DC/DC converters 31A, 31B; a switch 32; a storage box 33, the storage box 33 accommodating the two DC/DC converters 31A, 31B and the switch 32; and two control units 34A, 34B (fig. 2).

The two DC/DC converters 31A and 31B are each a known DC/DC converter composed of a switching element, a coil, and the like. Each of the two DC/DC converters 31A, 31A lowers the power supply voltage of the drive battery 2 and converts it into a voltage suitable for the first and second sub-batteries 4A, 4B, the automatic operation load 5, and the general load 6.

the first sub-battery 4A is connected to the output of the DC/DC converter 31A. The second sub-battery 4B is connected to the output of the DC/DC converter 31B.

The switch 32 is provided between the outputs of the two DC/DC converters 31A and 31B. When the switch 32 is turned on, the outputs of the two DC/DC converters 31A, 31B are connected, the output of the DC/DC converter 31A is connected to the second sub-battery 4B, and the output of the DC/DC converter 31B is connected to the first sub-battery 4A. When the switch 32 is turned off, the outputs of the two DC/DC converters 31A, 31B are disconnected from each other, the output of the DC/DC converter 31A is disconnected from the second sub-battery 4B, and the output of the DC/DC converter 31B is disconnected from the first sub-battery 4A.

the switch 32 is controlled to be turned on/off by both control units 34A, 34B (fig. 2) which will be described later. The control units 34A and 34B turn on the switch 32 in a normal state. As a result, in the normal state, the first sub-battery 4A is charged with the output power of both the two DC/DC converters 31A, 31B, and the second sub-battery 4B is also charged with the output power of both the two DC/DC converters 31A, 31B.

On the other hand, when an abnormality occurs in any one of the two DC/DC converters 31A and 31B, the control units 34A and 34B turn off the switch 32. For example, when the switch 32 is opened when an abnormality occurs in the DC/DC converter 31A, the connection between the abnormal DC/DC converter 31A and the second sub-battery 4B is disconnected. Thus, the output voltage of the abnormal DC/DC converter 31A is not supplied to the second sub-battery 4B and the automatic operation load 5, and only the output voltage of the normal DC/DC converter 31B is supplied to the second sub-battery 4B and the automatic operation load 5, so that the supply of electric power to the automatic operation load 5 can be continued.

Similarly, when the switch 32 is turned off at the time of occurrence of an abnormality of the DC/DC converter 31B, the connection between the abnormal DC/DC converter 31B and the first sub-battery 4A is disconnected. Thus, the output voltage of the abnormal DC/DC converter 31B is not supplied to the first sub-battery 4A, the automatic operation load 5, and the general load 6, and only the output voltage of the normal DC/DC converter 31A is supplied to the first sub-battery 4A, the automatic operation load 5, and the general load 6, so that the supply of electric power to the automatic operation load 5 and the general load 6 can be continued.

the two DC/DC converters 31A and 31B are accommodated in one storage box 33. That is, the two DC/DC converters 31A, 31B are accommodated in one space separated from the external space by one storage tank 33. Since the two DC/DC converters 31A, 31B are accommodated in one storage tank 33 in this way, a common cooling system can be used for the two DC/DC converters 31A, 31B, so that cost reduction can be achieved.

As the cooling system, a known cooling system capable of cooling the temperature in the storage tank 33 may be used. As the cooling system, for example, a configuration in which a cooling fan for sucking outside air into the storage tank 33 is provided, or a structure in which a heat exchanger or the like is provided in the storage tank 33 is conceivable. In addition, the cooling medium may be a liquid or a gas.

The switch 32 is also accommodated in a storage box 33. Therefore, by disposing the switch 32 close to the DC/DC converters 31A, 31B, on/off of the switch 32 can be controlled by the control units 34A, 34B that control the DC/DC converters 31A, 31B, which will be described later. That is, it is not necessary to provide a control unit for controlling on/off of the switch 32 separately from the control units 34A, 34B, and cost reduction can be achieved.

For example, the two control units 34A, 34B are constituted by microcomputers constituted by a CPU, a ROM, a RAM, and the like, and control the two DC/DC converters 31A and 31B independently, respectively. "independently control" means that each of the two control units 34A, 34B is composed of different parts, and means that the microcomputer constituting the control unit 34A is a separate part from the microcomputer constituting the control unit 34B.

By thus providing the two control units 34A and 34B and independently controlling the DC/DC converters 31A and 31B, respectively, even if either one of the control units 34A and 34B fails, the operation of the corresponding DC/DC converter can be continued with the other control unit. Therefore, the interruption of the power supply to the automatic operation load 5 can be prevented.

The control unit 34A performs conversion control of the DC/DC converter 31A, and the control unit 34B performs conversion control of the DC/DC converter 31B, thereby outputting desired output voltages from the DC/DC converters 31A and 31B. The two control units 34A and 34B may be housed inside the storage box 33 or outside the storage box 33.

Next, the switching control by the two control units 34A and 34B will be described. The two control units 34A and 34B control the operations of the DC/DC converters 31A and 31B through on/off control of switching elements included in the two DC/DC converters 31A and 31B, respectively.

In the present embodiment, the two control units 34A and 34B start control of the DC/DC converters 31A and 31B in response to, for example, turning on of the ignition switch, but do not start conversion control at the same time, and perform coordinated control shown below. In the cooperative control, first, the control unit 34B starts the conversion control of the DC/DC converter 31B. At this time, the operation of the DC/DC converter 31A is stopped. Thereafter, when the output power of the DC/DC converter 31B becomes high to some extent, the other control unit 34A starts the conversion control of the DC/DC converter 31A.

Thus, when the output power at the start of conversion is low, the operations of the two DC/DC converters 31A and 31B are not performed, so that the efficiency can be improved. Incidentally, the timing to start the conversion control of the DC/DC converter 31A may be a timing at which the output voltage of the DC/DC converter 31B exceeds a threshold value, or may be a timing when a predetermined time elapses from the start of the control of the DC/DC converter 31B.

The above effect was confirmed by simulation. Fig. 3 is a graph showing a relationship between output power and efficiency of each of the DC/DC converters 31A and 31B. The two DC/DC converters 31A and 31B have the same output power-to-power characteristic. As shown in the figure, when the output power is low, the efficiency of the DC/DC converters 31A and 31B is low, and as the output power increases, the efficiency abruptly increases. Then, when the output power becomes high to some extent, the efficiency gradually decreases as the output power increases.

in the case where the control units 34A and 34B perform the cooperative control of the DC/DC converters 31A and 31B having the above characteristics, and in the case where the control units 34A and 34B do not perform the cooperative control (i.e., in the case where the control of the two DC/DC conversions of the control units 31A and 31B is simultaneously started), the relationship between the efficiency and the output power is simulated. The results are shown in FIG. 4. As is clear from the figure, by performing the cooperative control, the efficiency when the output power is low can be improved.

According to the above embodiment, the output power versus efficiency characteristics of the two DC/DC converters 31A and 31B are the same, but the present invention is not limited thereto. For example, as shown in fig. 5 and 7, the output power versus efficiency characteristics of the two DC/DC converters 31A and 31B may be different. Fig. 6 is a graph showing the relationship of efficiency with respect to each output power when the DC/DC converters 31A and 31B having the characteristics shown in fig. 5 are subjected to the cooperative control and are not subjected to the cooperative control. Further, fig. 8 is a graph showing the relationship of efficiency with respect to each output power when the DC/DC converters 31A and 31B having the characteristics shown in fig. 7 are subjected to the cooperative control and are not subjected to the cooperative control. As shown in fig. 5 and 7, the DC/DC converter 31B has high efficiency when the output power is low, but low efficiency when the output power is high, as compared with the DC/DC converter 31A.

In this case, when the control units 34A and 34B start the conversion control of the DC/DC converter 31B that is efficient when the output power is low first and start the conversion control of the DC/DC converter 31A that is efficient when the output power is high later, the efficiency when the output power is low can be further improved, as shown in fig. 6 and 8.

in addition, the two control units 34A and 34B monitor each other. When any one of the two control units 34A and 34B detects a failure of the other of the two control units 34A and 34B, the one control unit determines that an abnormality occurs in one of the DC/DC converters 31A or 31B, and turns off the switch 32. The control unit 34A monitors a control signal output from itself to the DC/DC converter 31A and a control signal output from the control unit 34B to the DC/DC converter 31B, and turns off the switch 32 when no signal is output from either.

Likewise, the control unit 34B also monitors the output signal output from itself to the DC/DC converter 31B and the control signal output from the control unit 34A to the DC/DC converter 31A, and turns off the switch 32 when no signal is output from either one.

When the control unit 34A fails, a desired output voltage is not output from the DC/DC converter 31A. In the present embodiment, when the control unit 34A fails, the control units 34A and 34B can turn off the switch 32 and turn off the abnormal DC/DC converter 31A. The second sub-battery 4B and the automatic operation load 5 can continue to be supplied with electric power by the output voltage from the normal DC/DC converter 31B.

Further, when the control unit 34B fails, the control units 34A and 34B can turn off the switch 32 and turn off the abnormal DC/DC converter 31B. The first sub-battery 4A, the automatic operation load 5, and the general load 6 can be continuously supplied with electric power by the output from the normal DC/DC converter 31A.

Incidentally, according to the above-described embodiment, the two DC/DC converters 31A and 31B are accommodated in one storage box 33, but the present invention is not limited thereto. The two DC/DC converters 31A and 31B may be accommodated in separate storage tanks.

Further, according to the above-described embodiment, the DC/DC converters 31A and 31B are independently controlled by the two control units 34A and 34B, respectively, but the present invention is not limited thereto. The two DC/DC converters 31A and 31B may be controlled by one control unit.

Further, according to the above-described embodiment, the switch 32 is accommodated in the storage box 33, but the present invention is not limited thereto. The switch 32 may be provided outside the storage box 33.

Further, according to the above-described embodiment, the power supply device 1 is provided with two sub-batteries of the first sub-battery 4A and the second sub-battery 4B, but the present invention is not limited thereto. Only the first sub-battery 4A may be provided.

Further, according to the above-described embodiment, the control units 34A and 34B first start the conversion control of the DC/DC converter 31B and then start the conversion control of the DC/DC converter 31A, but the present invention is not limited thereto. The conversion control of the DC/DC converter 31A may be started first, and thereafter the conversion control of the DC/DC converter 31B may be started.

It is to be understood that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the present invention.