Charger

Abstract

To provide a technique that can increase the power conversion efficiency in a charger.SOLUTION: A charger to be mounted on an electric vehicle includes: an electric power conversion device that converts input power supplied from an external charging power source into charging power to be supplied to a battery mounted on the electric vehicle; and a control device that controls operation of the electric power conversion device. The control device determines the maximum value of the input power to be supplied to the electric power conversion device from the charging power source, and intermittently operates the electric power conversion device based on the determined maximum value of the input power and a power rating of the electric power conversion device.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a charger mounted on an electric vehicle.

Background Art

[0002] Patent Document 1 discloses an intermittent operation of a power conversion device as a power adjustment method that emphasizes loss reduction in a low output region. In the intermittent operation, the transmission power is adjusted on average by providing a power transmission pause period. As a result, stable operation and loss reduction in the low output region of the power conversion device are achieved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, a charger mounted on an electric vehicle is designed such that its power conversion efficiency is maximized at the rated power (i.e., the maximum input power). However, due to external factors such as the specifications of the charging cable connected to the vehicle and the specifications of the charging power source used, the rated power is not always input to the charger. For example, it is also assumed that when the input power input to the charger is small compared to the rated power of the charger, the power conversion efficiency of the charger significantly decreases. This specification provides a technology capable of increasing the power conversion efficiency in a charger.

Means for Solving the Problems

[0005] This specification discloses a charger mounted on an electric vehicle. In a first aspect, the charger includes a power conversion device that converts input power supplied from an external charging power source into charging power supplied to a battery mounted on the electric vehicle, and a control device that controls the operation of the power conversion device. The control device determines a maximum value of the input power supplied from the charging power source to the power conversion device, and intermittently operates the power conversion device based on the determined maximum value of the input power and the rated power of the power conversion device.

[0006] According to the above configuration, the charger intermittently operates the power conversion device based on the maximum value of the input power and the rated power of the power conversion device. In particular, when the maximum value of the input power is small relative to the rated power of the power conversion device, the power conversion device can be intermittently operated. Therefore, even in a situation where the rated power is not necessarily input to the charger, the power conversion efficiency in the charger can be increased.

[0007] In a second aspect, in the first aspect, the control device may determine the maximum value of the input power using the input voltage input from the charging power source to the power conversion device and the maximum value of the input current input from the charging power source to the power conversion device.

[0008] In a third aspect, in the second aspect, the charger further includes a voltage sensor that detects the input voltage. The control device may obtain the input voltage from the voltage sensor and obtain the maximum value of the input current by communication with the charging power source side. According to the above configuration, the maximum value of the input power can be appropriately determined using the input voltage obtained from the voltage sensor and the maximum value of the input current obtained by communication from the charging power source side.

[0009] In the fourth aspect, in the above third aspect, the maximum value of the input current is the rated current of the charging cable of the charging power supply connected to the electric vehicle, and the control device may communicate with a CCID (Charge Circuit Interrupt Device) provided in the charging cable to obtain the rated current of the charging cable. According to the above configuration, the control device can appropriately determine the maximum value of the input power by using the rated current of the charging cable obtained by communication from the CCID.

[0010] In the fifth aspect, in any one of the first to fourth aspects above, when the maximum value of the input power is smaller than a predetermined threshold with respect to the rated power of the power conversion device, the control device may intermittently operate the power conversion device so that the power conversion efficiency of the power conversion device exceeds a predetermined reference value. For this reason, the power conversion efficiency in the charger can be increased.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] FIG. 1 is a schematic diagram of an electric vehicle 10 and a power system 50. On the power system 50 side, a charging power supply 52 and a charging cable 54 are provided. The charging power supply 52 outputs AC power. One end of the charging cable 54 is connected to the charging power supply 52. A connector 58 for connecting to the electric vehicle 10 (specifically, the inlet 12 of the electric vehicle 10) is provided at the other end of the charging cable 54. Further, a CCID (Charge Circuit Interrupt Device) 56 is provided in the charging cable 54. The CCID 56 has a control circuit for controlling the charging of the electric vehicle 10.

[0013] The electric vehicle 10 is equipped with a battery (not shown) and a motor for driving. The electric vehicle 10 is, for example, an electric vehicle, a plug-in hybrid vehicle, or the like. The electric vehicle 10 is equipped with a charger 20.

[0014] The battery of the electric vehicle 10 is charged by the electric power input from the charging power source 52 via the charging cable 54. As shown in FIG. 1, the inlet 12 is connected to the charger 20 via the power transmission line 14 and the connector 16. When the connector 58 of the charging cable 54 is connected to the inlet 12 of the electric vehicle 10, electric power is input to the charger 20 via the inlet 12, the power transmission line 14, and the connector 16. The charger 20 converts the input electric power and supplies the converted electric power to the battery.

[0015] The charger 20 includes a control device 22, a voltage sensor 24, an AC / DC converter 26, and a DC / DC converter 28. The voltage sensor 24 detects the input voltage from the power system 50. The AC / DC converter 26 converts the AC power from the power system 50 into DC power. The DC / DC converter 28 boosts the DC power output by the AC / DC converter 26. That is, the AC / DC converter 26 and the DC / DC converter 28 are power conversion devices that convert the input electric power supplied from the external charging power source 52 into the charging electric power supplied to the battery mounted on the electric vehicle 10. Since the circuit configurations of the AC / DC converter 26 and the DC / DC converter 28 are well known, detailed descriptions thereof are omitted.

[0016] The control device 22 is configured to be communicable with the AC / DC converter 26 and the DC / DC converter 28, and controls the operations of the AC / DC converter 26 and the DC / DC converter 28. Specifically, for example, the control device 22 controls the AC / DC converter 26 and the DC / DC converter 28 by supplying a PWM signal to the AC / DC converter 26 and the DC / DC converter 28.

[0017] In addition, the control device 22 is configured to be communicable with the voltage sensor 24 and acquires the input voltage from the voltage sensor 24. Further, the control device 22 is configured to be communicable with the CCID 56 provided on the charging cable 54 on the power grid 50 side, and is configured to acquire the rated current of the charging cable 54 from the charging cable 54 by communication. Although details will be described later, the control device 22 determines the maximum value of the input power supplied to the DC / DC converter 28 from these input voltage and the rated current of the charging cable 54. Then, the control device 22 intermittently operates the DC / DC converter 28 based on the determined maximum value of the input power and the rated power of the DC / DC converter 28.

[0018] Here, "intermittent operation" means an operation mode in which a pause time for pausing power transmission is provided, and is also called a burst mode. In the intermittent operation of the DC / DC converter 28 of this embodiment, the operation time for switching the switching element of the DC / DC converter 28 and the pause time for pausing the switching of the switching element are repeated. Intermittent operation is an operation mode that emphasizes conversion efficiency, and is particularly used to reduce losses in the low output region.

[0019] Subsequently, with reference to FIG. 2, the processing executed by the control device 22 of the charger 20 will be described. The processing in FIG. 2 is started triggered by the connector 58 of the charging cable 54 being connected to the inlet 12.

[0020] In S10, the control device 22 detects the input voltage. Specifically, when the connector 58 of the charging cable 54 is connected to the inlet 12, power is input from the charging power source 52 to the charger 20, so a voltage is input to the charger 20. The voltage sensor 24 detects the input voltage supplied to the charger 20 and outputs the input voltage to the control device 22. Thereby, the control device 22 detects the input voltage.

[0021] In S12, the control device 22 acquires (i.e., receives) the rated current of the charging cable 54 from the CCID 56 through communication. Specifically, the charging cable 54 is provided with a control pilot signal line. The control device 22 receives the rated current of the charging cable 54 from the CCID 56 via the control pilot signal line of the charging cable 54. Note that the order of the processes of S10 and S12 is an example, and the process of S12 may be executed prior to the process of S10.

[0022] In S14, the control device 22 determines the maximum value of the input power. Specifically, the control device 22 determines the maximum value of the input power using the input voltage detected in S10 and the rated current received in S12. More specifically, the control device 22 determines the maximum value of the input power by calculating the product of the input voltage and the rated current.

[0023] In S16, the control device 22 determines whether the determined maximum value of the input power is near the rated power of the DC / DC converter 28. Specifically, the control device 22 determines whether the maximum value of the input power is smaller than a predetermined threshold with respect to the rated power. When the maximum value of the input power is smaller than a predetermined threshold with respect to the rated power (i.e., when the maximum value of the input power is not near the rated power), the control device 22 determines NO in S16 and proceeds to S30. On the other hand, when the maximum value of the input power is not smaller than a predetermined threshold with respect to the rated power (i.e., when the maximum value of the input power is near the rated power), the control device 22 determines YES in S16 and proceeds to S20.

[0024] Here, the reasons for executing the processes of S10 to S16 described above will be explained. Generally, the charger 20 (especially the DC / DC converter 28) is designed such that its power conversion efficiency is maximized when the rated power is input to the charger 20. However, due to external factors such as the specifications of the charging cable 54 connected to the electric vehicle 10 (e.g., the rated current of the charging cable 54) and the specifications of the charging power source 52 used (e.g., the output voltage of the charging power source 52), the rated power of the charger 20 is not necessarily input to the charger 20. For example, the rated current of the charging cable 54 may be smaller than the current required to input the rated power of the charger 20 to the charger 20. In this case, the input power input to the charger 20 becomes smaller than the rated power of the charger 20. In such a case, compared with the case where the rated power is input to the charger 20, the power conversion efficiency of the charger 20 decreases.

[0025] Assuming such a situation, the control device 22 of the present embodiment executes the processes of S10 to S16. By executing the processes of S10 to S16, the control device 22 can increase the power conversion efficiency of the charger 20 by determining whether to perform intermittent operation based on the input power input to the charger 20 and the rated power of the charger 20, and determining the pause time in the case of intermittent operation.

[0026] Returning to the description of the flowchart again. In S20, the control device 22 determines not to perform intermittent operation. That is, in this case, no pause time is provided in the power conversion control described later.

[0027] In S30, the control device 22 determines to perform intermittent operation based on the maximum value of the input power. Specifically, the control device 22 determines the pause time based on the maximum value of the input power and the rated power of the charger 20. The pause time is set to a time such that the power conversion efficiency of the DC / DC converter 28 exceeds a predetermined reference value.

[0028] In S40, the control device 22 starts power conversion control. Specifically, the control device 22 starts controlling the operations of the AC / DC converter 26 and the DC / DC converter 28 (for example, starts supplying a PWM signal). In particular, in S40 following S20, the control device 22 operates the DC / DC converter 28 in an intermittent manner, and in S40 following S30, the control device 22 does not operate the DC / DC converter 28 in an intermittent manner. The pause time of the intermittent operation is set to a time such that the power conversion efficiency of the DC / DC converter 28 exceeds a predetermined reference value.

[0029] In this way, when the maximum value of the input power is smaller than a predetermined threshold with respect to the rated power, the control device 22 of this embodiment operates the DC / DC converter 28 in an intermittent manner. For this reason, even in a situation where power smaller than the rated power is input to the DC / DC converter 28, the power conversion efficiency in the DC / DC converter 28 can be increased.

[0030] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above.

[0031] (Modification Example 1) In the above embodiment, the maximum value of the input power is determined by the control device 22 (S10 to S14 in FIG. 2). Instead of this, the control device 22 does not necessarily determine the maximum value of the input power by itself. For example, the control device 22 may acquire the maximum value of the input power from the outside through communication. In this case, the charger 20 may not include the voltage sensor 24.

[0032] (Modification Example 2) In S12 of FIG. 2, instead of the rated current of the charging cable 54, the control device 22 may receive an allowable current that can vary according to, for example, the usage status of the charging cable 54. Also, the transmission entity of the rated current of the charging cable 54 does not have to be the CCID 56, and may be, for example, the charging power supply 52 or the like.

[0033] The technical elements described in this specification or the drawings exhibit technical utility either individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies exemplified in this specification or the drawings can achieve multiple objectives simultaneously, and achieving one of those objectives by itself has technical utility.

Description of Reference Numerals

[0034] 10: Electric vehicle, 12: Inlet, 14: Power transmission line, 16: Connector, 20: Charger, 22: Control device, 24: Voltage sensor, 26: AC / DC converter 26, 28: DC / DC converter, 50: Power system, 52: Charging power source, 54: Charging cable, 56: CCID, 58: Connector

Claims

1. A charger mounted on an electric vehicle, comprising: a power conversion device that converts input power supplied from an external charging power source into charging power supplied to a battery mounted on the electric vehicle; a control device that controls the operation of the power conversion device; The charger is provided with: The control device: determines the maximum value of the input power supplied from the charging power source to the power conversion device; Based on the determined maximum value of the input power and the rated power of the power conversion device, the power conversion device is intermittently operated. Charger.

2. The control device determines the maximum value of the input power by using the input voltage input from the charging power source to the power conversion device and the maximum value of the input current input from the charging power source to the power conversion device. The charger according to claim 1.

3. The charger further comprises a voltage sensor for detecting the input voltage, The control device acquires the input voltage from the voltage sensor and acquires the maximum value of the input current by communication with the charging power source side. The charger according to claim 2.

4. The maximum value of the input current is the rated current of the charging cable of the charging power source connected to the electric vehicle, The control device communicates with a CCID (Charge Circuit Interrupt Device) provided on the charging cable to acquire the rated current of the charging cable. The charger according to claim 3.

5. When the maximum value of the input power is smaller than a predetermined threshold with respect to the rated power of the power conversion device, the control device intermittently operates the power conversion device so that the power conversion efficiency of the power conversion device exceeds a predetermined reference value. The charger according to any one of claims 1 to 4.

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