US-12627214-B2 - Series-parallel switching method and apparatus, power conversion circuit, and electronic device

US12627214B2US 12627214 B2US12627214 B2US 12627214B2US-12627214-B2

Abstract

A series-parallel switching method and apparatus, a power conversion circuit, and an electronic device are provided. The power conversion circuit includes a control unit and two power conversion modules. The two power conversion modules are connected in series or connected in parallel. Either of the power conversion modules includes output terminals and first switch branches, where the first switch branches are connected to the output terminals, and the output terminals are configured to connect to a load. The first switch branches are connected to the control unit, and the first switch branches are configured to switch an operating state according to a control signal output by the control unit, to provide an energy discharge loop when the two power conversion modules are switched from a parallel connection to a series connection, where the operating state includes a stopping state and a running state.

Inventors

Meng Wu
Guiying LIN
Jinfeng Gao

Assignees

CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

Dates

Publication Date: 20260512
Application Date: 20230718

Claims (9)

1 . A power conversion circuit, comprising: a control unit, and two power conversion modules connected to the control unit, wherein the two power conversion modules are configured to be connected in a series connection mode or in a parallel connection mode; wherein each power conversion module comprises: an output terminal and a first switch branch, the first switch branch is connected to the output terminal, and the output terminal is connected to a load; and an input terminal and a second switch branch, the second switch branch is connected to the input terminal, and the input terminal is connected to a power grid; wherein an operating state of the first switch branch and the second switch branch each comprises a stopping state and a running state; the first switch branch is configured to switch the operating state of the first switching branch from the stopping state to the running state according to a first control signal output by the control unit, to provide an energy discharge loop when the two power conversion modules are switched from the parallel connection mode to the series connection mode, wherein energy stored in the two power conversion modules is released to the power grid via the energy discharge loop; and the second switch branch is configured to switch the operating state of the second switching branch from the stopping state to the running state according to a second control signal output by the control unit, to charge the output terminal using the power grid when the two power conversion modules are switched from the series connection mode to the parallel connection mode.
2 . The power conversion circuit according to claim 1 , wherein the power conversion circuit further comprises a first switch, a second switch, and a third switch that are connected in series, and the two power conversion modules comprise a first power conversion module and a second power conversion module, wherein a first end of the first switch is connected to a first end of the output terminal of the first power conversion module, a second end of the first switch is connected to a first end of the output terminal of the second power conversion module and a first end of the second switch, a second end of the second switch is connected to a second end of the output terminal of the first power conversion module and a first end of the third switch, and a second end of the third switch is connected to a second end of the output terminal of the second power conversion module; wherein when the first switch and the third switch are on and the second switch is off, the two power conversion modules are connected in parallel; or when the second switch is on and the first switch and the third switch are off, the two power conversion modules are connected in series.
3 . The power conversion circuit according to claim 1 , wherein the control unit is configured to: obtain a first voltage between two ends of the load and a maximum output voltage of each power conversion module; determine whether to switch the connection mode of the power conversion modules according to the first voltage between two ends of the load and the maximum output voltage of each power conversion module; and control the two power conversion modules to switch the connection mode when it is determined that the connection mode of the two power conversion modules needs to be switched.
4 . The power conversion circuit according to claim 3 , wherein in determining whether to switch the connection mode of the power conversion modules according to the first voltage between two ends of the load and a maximum output voltage of each power conversion module, the control unit is configured to: when a current connection mode of the two power conversion modules is the series connection mode, and the first voltage is less than a difference between the maximum output voltage of each power conversion module and a first voltage threshold, determine that the connection mode of the two power conversion modules needs to be switched to the parallel connection mode; and when the current connection mode of the two power conversion modules is the parallel connection mode, and the first voltage is greater than a sum of the maximum output voltage of each power conversion module and a second voltage threshold, determine that the connection mode of the two power conversion modules needs to be switched to the series connection mode.
5 . The power conversion circuit according to claim 2 , wherein when the connection mode of the two power conversion modules is switched from the parallel connection mode to the series connection mode, the first switch and the third switch are switched to off, and delayed for a first duration; the first control signal is applied to the first switch branch at an end of the first duration to control the first switch branch to switch from the stopping state to the running state; and when a voltage between the first end and the second end of the output terminal of either of the power conversion modules is not greater than a third voltage threshold, the second switch is switched to on.
6 . The power conversion circuit according to claim 2 , wherein when the connection mode of the two power conversion modules is switched from the series connection mode to the parallel connection mode, the second switch is switched to off, and delayed for a second duration; the second control signal is applied to the second switch branch at an end of the second duration to control the second switch branch to switch from the stopping state to the running state; and when a voltage between the first end and the second end of the output terminal of either of the power conversion modules is not less than a fourth voltage threshold, the first switch and the third switch are switched to be on.
7 . A charging device, comprising the power conversion circuit according to claim 1 .
8 . The charging device according to claim 7 , wherein the charging device is a charging pile or a charger.
9 . A series-parallel switching apparatus in a power conversion circuit, comprising: a processor, and memory storing program codes for execution by the processor; wherein the power conversion circuit is configured to connect to a load and a power grid, the power conversion circuit comprises two power conversion modules connected in a series connection mode or in a parallel connection mode, wherein each power conversion module comprises: an output terminal and a first switch branch, the first switch branch is connected to the output terminal, and the output terminal is connected to the load; an input terminal and a second switch branch, the second switch branch is connected to the input terminal, and the input terminal is connected to the power grid; wherein an operating state of the first switch branch and the second switch branch each comprises a stopping state and a running state; the first switch branch is configured to switch the operating state of the first switch branch from the stopping state to the running state according to a first control signal output by the apparatus, to provide an energy discharge loop when the two power conversion modules are switched from the parallel connection mode to the series connection mode, wherein energy stored in the two power conversion modules is released to the power grid via the energy discharge loop; and the second switch branch is configured to switch the operating state of the second switch branch from the stopping state to the running state according to a second control signal output by the apparatus, to charge the output terminal using the power grid when the two power conversion modules are switched from the series connection mode to the parallel connection mode; wherein when executed by the processor, the program codes cause the apparatus to: obtain a first voltage between two ends of the load and a maximum output voltage of each power conversion module; determine whether to switch the connection mode of the power conversion modules according to the first voltage between two ends of the load and the maximum output voltage of each power conversion module; and control the two power conversion modules to switch the connection mode when it is determined that the connection mode of the two power conversion modules needs to be switched; wherein in determining whether to switch the connection mode of the power conversion modules according to the first voltage between two ends of the load and a maximum output voltage of each power conversion module, the program codes cause the apparatus to: when a current connection mode of the two power conversion modules is the series connection mode, and the first voltage is less than a difference between the maximum output voltage of each power conversion module and a first voltage threshold, determine that the connection mode of the two power conversion modules needs to be switched to the parallel connection mode; and when the current connection mode of the two power conversion modules is the parallel connection mode, and the first voltage is greater than a sum of the maximum output voltage of each power conversion module and a second voltage threshold, determine that the connection mode of the two power conversion modules needs to be switched to the series connection mode.

Description

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of International Patent Application No. PCT/CN2021/126759, filed on Oct. 27, 2021, which is incorporated by reference in its entirety. TECHNICAL FIELD This application relates to the field of charging technologies, and in particular, to a series-parallel switching method and apparatus, a power conversion circuit, and an electronic device. BACKGROUND In recent years, a quantity of motor vehicles in China has increased significantly, urban traffic congestion has increased, and automobile exhaust has become a main source of urban air pollution. To alleviate air pollution and reduce environmental problems caused by traditional fuel automobile exhaust, electric vehicle technologies are advancing rapidly and national policies are published to promote development, accompanied by a rapid increase of a new energy vehicle population in the market. Charging devices such as charging piles or vehicular chargers are basic facilities for new energy vehicles. Construction of the charging devices has become an important task to promote transformation and upgrade of vehicles in China and assist in green transportation. In addition, as electric vehicles are continuously diversified, required charging voltages also change continuously. To broaden an output voltage range of a charging pile and reduce costs while improving efficiency, a plurality of power conversion modules in a series/parallel structure are usually used for implementation, to improve adaptability of a charging device to different charging objects. Specifically, the plurality of power conversion modules are in a series output state when a large voltage output is required, and the plurality of power conversion modules are in a parallel output state when a low voltage output is required. However, in the prior art, when the plurality of power conversion modules are to be switched from a parallel connection to a series connection, usually, an additional module needs to be added to assist in completing the switching process, resulting in higher costs and a larger volume. SUMMARY This application is intended to provide a series-parallel switching method and apparatus, a power conversion circuit, and an electronic device. In this application, a parallel-series switching process can be implemented without adding an additional module, so that the power conversion circuit can have lower costs and a smaller volume. To achieve the foregoing objective, according to a first aspect, this application provides a power conversion circuit. The circuit includes a control unit and two power conversion modules. The two power conversion modules are connected in series or connected in parallel. Either of the power conversion modules includes an output terminal and a first switch branch, where the first switch branch is connected to the output terminal, and the output terminal is configured to connect to a load. The first switch branch is connected to the control unit, and the first switch branch is configured to switch an operating state according to a first control signal output by the control unit, to provide an energy discharge loop when the two power conversion modules are switched from a parallel connection to a series connection, where the operating state includes a stopping state and a running state. When the two power conversion modules are switched from the parallel connection to the series connection, the two power modules need to discharge energy, that is, discharge power. Then energy can be discharged by using the energy discharge loop provided by the first switch branches in the two power conversion modules. Because no additional discharge branch is added as in the related art, costs are lower and a volume is smaller. In addition, there is no need to add an additional discharge branch control process. In comparison with a solution to adding a discharge branch in the related art, there is less difficulty in control. Moreover, an existing solution to controlling the first switch branch may be further simply improved to obtain a solution to controlling the first switch branch to implement an energy discharge process. This helps simplify the control solution in a series-parallel switching process of the two power conversion modules, thereby reducing difficulty in control. In an optional implementation, the power conversion module further includes an input terminal and a second switch branch. The second switch branch is connected to the input terminal, and the input terminal is configured to connect to an external input power supply. The second switch branch is connected to the control unit, and the second switch branch is configured to switch the operating state according to a second control signal output by the control unit, to charge the output terminal based on the input power supply when the two power conversion modules are switched from the series connection to the parallel connection. When the two