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 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 necessarily 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 that can increase the power conversion efficiency in the charger.

Means for Solving the Problems

[0005] This specification discloses a charger to be mounted on an electric vehicle. In a first embodiment, the charger comprises a power converter 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 converter, wherein the control device determines the maximum value of the input power supplied from the charging power source to the power converter, and operates the power converter intermittently based on the determined maximum value of the input power and the rated power of the power converter.

[0006] According to the above configuration, the charger intermittently operates the power converter based on the maximum input power and the rated power of the power converter. In particular, the power converter can be operated intermittently when the maximum input power is small compared to the rated power of the power converter. This makes it possible to improve the power conversion efficiency of the charger even in situations where the rated power is not always input to the charger.

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

[0008] In a third embodiment, the control device further comprises a voltage sensor for detecting the input voltage, and the control device acquires the input voltage from the voltage sensor and the maximum value of the input current by communication with the charging power supply. With the above configuration, the maximum value of the input power can be appropriately determined by using the input voltage acquired from the voltage sensor and the maximum value of the input current acquired by communication from the charging power supply.

[0009] In a fourth embodiment, in the third embodiment, 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 on 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 embodiment, in any one of the first to fourth embodiments, the control device may intermittently operate the power converter so that the power conversion efficiency of the power converter exceeds a predetermined reference value when the maximum value of the input power is less than a predetermined threshold value relative to the rated power of the power converter. This makes it possible to increase the power conversion efficiency of the charger. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the electric vehicle and power system. [Figure 2] This is a flowchart of the processes performed by the charger. [Modes for carrying out the invention]

[0012] Figure 1 is a schematic diagram of the electric vehicle 10 and the power system 50. The power system 50 is equipped with a charging power supply 52 and a charging cable 54. The charging power supply 52 outputs AC power. One end of the charging cable 54 is connected to the charging power supply 52. ​​The other end of the charging cable 54 is equipped with a connector 58 for connection to the electric vehicle 10 (specifically, the inlet 12 of the electric vehicle 10). The charging cable 54 is also equipped with a CCID (Charge Circuit Interrupt Device) 56. The CCID 56 has a control circuit for controlling the charging of the electric vehicle 10.

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

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

[0015] The charger 20 comprises 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. In other words, the AC / DC converter 26 and the DC / DC converter 28 are power conversion devices that convert the input power supplied from an external charging power source 52 into charging power supplied to the battery mounted on the electric vehicle 10. The circuit configurations of the AC / DC converter 26 and the DC / DC converter 28 are well known, so a detailed explanation will be omitted.

[0016] The control device 22 is configured to communicate with the AC / DC converter 26 and the DC / DC converter 28, and controls the operation 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 PWM signals to them.

[0017] Furthermore, the control device 22 is configured to communicate with the voltage sensor 24 and obtains the input voltage from the voltage sensor 24. In addition, the control device 22 is configured to communicate with the CCID 56 provided on the charging cable 54 on the power system 50 side and is configured to obtain the rated current of the charging cable 54 from the charging cable 54 via communication. As will be described in more detail later, the control device 22 determines the maximum value of the input power supplied to the DC / DC converter 28 from these input voltages and the rated current of the charging cable 54. Then, the control device 22 operates the DC / DC converter 28 intermittently based on the determined maximum value of the input power and the rated power of the DC / DC converter 28.

[0018] Here, "intermittent operation" refers to an operating mode that includes pauses in power transmission, and is also called burst mode. In the intermittent operation of the DC / DC converter 28 in this embodiment, the DC / DC converter 28 repeatedly alternates between an operating time in which the switching elements are switched and a pause time in which the switching of the switching elements is paused. Intermittent operation is an operating mode that prioritizes conversion efficiency and is used in particular to reduce losses in the low-power region.

[0019] Next, referring to Figure 2, the process performed by the control device 22 of the charger 20 will be described. The process in Figure 2 is triggered when the connector 58 of the charging cable 54 is 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 supply 52 to the charger 20, and 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. As a result, 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 in S10 and S12 is an example, and the process in S12 may be executed prior to the process in 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 the rated power by more than a predetermined threshold. When the maximum value of the input power is smaller than the rated power by more than a predetermined threshold (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 the rated power by more than a predetermined threshold (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 reason for executing the above processes S10 to S16 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 (e.g., the rated current of the charging cable 54) connected to the electric vehicle 10 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, the power conversion efficiency of the charger 20 decreases as compared with the case where the rated power is input to the charger 20.

[0025] Assuming such a situation, the control device 22 of the present embodiment executes the processes S10 to S16. By executing the processes 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 explanation of the flowchart again. The control device 22 determines not to perform intermittent operation in S20. That is, in this case, no pause time is provided in the subsequent power conversion control.

[0027] The control device 22 determines to perform intermittent operation based on the maximum value of the input power in S30. 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 operation of the AC / DC converter 26 and the DC / DC converter 28 (for example, by starting to supply a PWM signal). In particular, in S40 after S20, the control device 22 operates the DC / DC converter 28 intermittently, but in S40 after S30, it does not operate the DC / DC converter 28 intermittently. The pause time for 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, the control device 22 of this embodiment operates the DC / DC converter 28 intermittently when the maximum input power is less than a predetermined threshold relative to the rated power. As a result, even when the DC / DC converter 28 is input with power less than the rated power, the power conversion efficiency of the DC / DC converter 28 can be increased.

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

[0031] (Modification 1) In the above embodiment, the maximum value of the input power was determined by the control device 22 (S10-S14 in Figure 2). Alternatively, the control device 22 does not have to determine the maximum value of the input power itself. For example, the control device 22 may obtain the maximum value of the input power from an external source via communication. In this case, the charger 20 does not need to be equipped with a voltage sensor 24.

[0032] (Modification 2) In S12 of Figure 2, the control device 22 may receive, for example, an allowable current that can vary depending on the usage status of the charging cable 54, instead of the rated current of the charging cable 54. Also, the entity transmitting the rated current of the charging cable 54 does not have to be CCID 56, but may be, for example, the charging power supply 52.

[0033] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

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

Claims

1. A charger installed in an electric vehicle, 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 for controlling the operation of the power converter, Equipped with, The control device is The maximum value of the input power supplied from the charging power source to the power converter is determined. Based on the determined maximum input power and the rated power of the power converter, the power converter is operated intermittently. charger.

2. The charger according to claim 1, wherein the control device determines the maximum value of the input power using the input voltage input from the charging power supply to the power converter and the maximum value of the input current input from the charging power supply to the power converter.

3. The system further includes a voltage sensor that detects the aforementioned input voltage, The charger according to claim 2, wherein 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 supply side.

4. 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. The charger according to claim 3, wherein the control device communicates with a CCID (Charge Circuit Interrupt Device) provided on the charging cable to obtain the rated current of the charging cable.

5. The charger according to any one of claims 1 to 4, wherein the control device intermittently operates the power converter so that the power conversion efficiency of the power converter exceeds a predetermined reference value when the maximum value of the input power is less than a predetermined threshold value relative to the rated power of the power converter.

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