Power conversion apparatus and charging device

Abstract

The present application provides a power conversion apparatus, comprising: N alternating current-direct current (AC-DC) conversion circuits, N input power supply lines and a detection apparatus, wherein the N AC-DC conversion circuits are connected in parallel, and the N input power supply lines are in one-to-one correspondence with N power conversion circuits. Each AC-DC conversion circuit is used for rectifying an alternating current outputted from a corresponding input power supply line and outputting a direct current. The detection apparatus comprises a first port and a second port, and the detection apparatus is used for: obtaining leakage currents of the N input power supply lines via the first port and obtaining the current or voltage of an ith input power supply line via the second port; and on the basis of the leakage currents of the N input power supply lines and the current or voltage of the ith input power supply line, determining a leakage current of the power conversion apparatus, wherein N is a positive integer, and N≥2, and 1≤i≤N. The solution can solve the problem of leakage current protection on an alternating-current input side.

Description

Power conversion device and charging equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 22, 2023, with application number 202311785850.2 and invention name “A power conversion device and charging equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of energy technology, and more specifically, to a power conversion device and a charging device. Background Art

[0003] With the rapid development of new energy vehicles, the use of car charging equipment as supporting facilities is becoming increasingly common. Car charging equipment mainly includes alternating current-direct current (AC-DC) converters and direct current-direct current (DC-DC) converters. The AC-DC converter is used to convert AC power output from the power grid into DC power, while the DC-DC converter is used to convert DC power output from the AC-DC converter into DC charging energy, thereby charging new energy vehicles.

[0004] In actual use, due to the increasing requirements for charging rates of new energy vehicles, multiple AC-DC conversion circuits connected in parallel are generally set up in the car charging equipment. Each AC-DC conversion circuit performs power conversion processing on the AC power output by the power grid to improve the power conversion capability of the car charging equipment from AC to DC, thereby realizing high-power charging of new energy vehicles by the car charging equipment.

[0005] However, most AC-DC converters in car charging equipment are non-isolated, and cannot solve the leakage protection problem on the AC input side in AC input multi-circuit AC power supply scenarios. Summary of the Invention

[0006] The present application provides a power conversion device that can solve the leakage protection problem on the AC input side in an AC input multi-circuit AC power supply scenario to meet the requirements of personal electric shock protection or electrical fire protection.

[0007] In a first aspect, a power conversion device is provided, comprising N AC-DC conversion circuits, N input power lines, and a detection device, wherein the N AC-DC conversion circuits are connected in parallel, and the N input power lines correspond one-to-one to the N power conversion circuits, and each AC-DC conversion circuit is used to rectify the AC power output from the corresponding input power line and output DC power; the detection device comprises a first port and a second port, and the detection device is used to: obtain leakage currents of the N input power lines through the first port, and obtain the current or voltage of the i-th input power line through the second port; determine the leakage current of the power conversion device based on the leakage currents of the N input power lines and the current or voltage of the i-th input power line; wherein N is a positive integer, and N≥2, 1≤i≤N.

[0008] According to the above technical solution, the detection device obtains the leakage current of N input power lines through the first port and the voltage or current of the i-th input power line through the second port. Based on the leakage current on each input power line and the voltage or current on the i-th input power line, a vector operation is performed to determine the leakage current of the power conversion device. This solves the leakage protection problem on the AC input side in AC power supply scenarios with multiple AC input circuits and meets requirements for personal electric shock protection or electrical fire protection.

[0009] In conjunction with the first aspect, in certain implementations of the first aspect, the detection device is further configured to: when the leakage current of the power conversion device is greater than or equal to a set threshold, control the N input power lines to be disconnected. According to the above technical solution, the detection device controls the N input power lines to be disconnected when the leakage current is greater than or equal to the set threshold. This can solve the leakage protection problem on the AC input side in AC power supply scenarios with multiple AC input circuits, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0010] In conjunction with the first aspect, in certain implementations of the first aspect, the power conversion device further includes: N first sensors, corresponding one-to-one to the N input power lines, connected to the first port, wherein each first sensor is configured to measure and output the leakage current of a corresponding input power line among the N input power lines; and a second sensor, disposed on the i-th input power line and connected to the second port, configured to measure and output the current or voltage of the i-th input power line. According to the above technical solution, leakage protection issues on the AC input side can be addressed in AC input multi-circuit AC power supply scenarios, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0011] In conjunction with the first aspect, in certain implementations of the first aspect, the detection device is specifically configured to perform a vector operation based on the leakage current of each input power line and the current or voltage of the i-th input power line to determine the leakage current of the power conversion device; the direction of the current or voltage of the i-th input power line is used as a phase reference during the vector operation. This technical solution can address leakage protection issues on the AC input side in AC power supply scenarios with multiple AC input circuits, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0012] In conjunction with the first aspect, certain implementations of the first aspect further include: N switching devices corresponding one-to-one to the N input power lines, wherein each switching device is provided on a corresponding one of the N input power lines, and the switching device is used to control the on / off state of the input power line; and the detection device is specifically configured to control the N switching devices to be disconnected when the leakage current of the power conversion device is greater than or equal to the set threshold. According to the above technical solution, it is possible to solve the leakage protection problem on the AC input side in a multi-circuit AC power supply scenario, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0013] In conjunction with the first aspect, in certain implementations of the first aspect, the switching device includes at least one of the following: a circuit breaker, an isolating switch, a relay, a contactor, an insulated gate bipolar transistor (IGBT), or a metal oxide semiconductor field effect transistor (MOSFIT). This technical solution can address leakage protection issues on the AC input side in a multi-circuit AC power supply scenario, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0014] In a second aspect, a charging device is provided, comprising a power conversion device and at least one charging terminal, the power conversion device being connected to the at least one charging terminal, the power conversion device being configured to receive alternating current (AC) power input from an external power grid, convert the AC power into DC power, and output the DC power to the at least one charging terminal. The power conversion device comprises N AC-DC conversion circuits, N input power lines, and a detection device, the N AC-DC conversion circuits being connected in parallel, the N input power lines corresponding one-to-one to the N power conversion circuits, and each AC-DC conversion circuit being configured to rectify the AC power output from the corresponding input power line and output DC power. The detection device comprises a first port and a second port, the detection device being configured to: obtain leakage currents of the N input power lines via the first port, and obtain the current or voltage of the i-th input power line via the second port; and determine the leakage current of the power conversion device based on the leakage currents of the N input power lines and the current or voltage of the i-th input power line. Wherein, N is a positive integer, and N ≥ 2, and 1 ≤ i ≤ N.

[0015] According to the above technical solution, the detection device obtains the leakage current of N input power lines through the first port and the voltage or current of the i-th input power line through the second port. Based on the leakage current on each input power line and the voltage or current on the i-th input power line, a vector operation is performed to determine the leakage current of the power conversion device. This solves the leakage protection problem on the AC input side in AC power supply scenarios with multiple AC input circuits and meets requirements for personal electric shock protection or electrical fire protection.

[0016] In conjunction with the second aspect, in certain implementations of the second aspect, the detection device is further configured to: when the leakage current of the power conversion device is greater than or equal to a set threshold, control the N input power lines to be disconnected. According to the above technical solution, the detection device controls the N input power lines to be disconnected when the leakage current is greater than or equal to the set threshold. This can solve the leakage protection problem on the AC input side in AC power supply scenarios with multiple AC input circuits, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0017] In conjunction with the second aspect, in certain implementations of the second aspect, the charging device further includes: N first sensors, corresponding one-to-one to the N input power lines, connected to the first port, wherein each first sensor is configured to measure and output the leakage current of a corresponding input power line among the N input power lines; and a second sensor, disposed on the i-th input power line and connected to the second port, configured to measure and output the current or voltage of the i-th input power line. According to the above technical solution, leakage protection issues on the AC input side can be resolved in AC input multi-circuit AC power supply scenarios, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0018] In conjunction with the second aspect, in certain implementations of the second aspect, the detection device is specifically configured to perform a vector operation based on the leakage current of each input power line and the current or voltage of the i-th input power line to determine the leakage current of the power conversion device; the direction of the current or voltage of the i-th input power line is used as a phase reference during the vector operation. This technical solution can address leakage protection issues on the AC input side in AC power supply scenarios with multiple AC input circuits, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0019] In conjunction with the second aspect, in certain implementations of the second aspect, the charging device further includes: N switching devices corresponding one-to-one to the N input power lines, wherein each switching device is provided on a corresponding one of the N input power lines and is configured to control the on / off state of the input power line; and the detection device is specifically configured to control the N switching devices to be disconnected when the leakage current of the power conversion device is greater than or equal to a set threshold. According to the above technical solution, leakage protection issues on the AC input side can be resolved in AC input multi-circuit AC power supply scenarios, thereby meeting requirements for personal electric shock protection or electrical fire protection.

[0020] In conjunction with the second aspect, in certain implementations of the second aspect, the switching device includes at least one of the following: a circuit breaker, an isolating switch, a relay, a contactor, an insulated gate bipolar transistor (IGBT), or a metal oxide semiconductor field effect transistor (MOSFIT). According to the above technical solution, in a multi-circuit AC power supply scenario with AC input, when the power conversion device is a non-isolated design, leakage protection issues on the AC input side can be resolved to meet requirements for personal electric shock protection or electrical fire protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of a charging system 10 provided in an embodiment of the present application.

[0022] FIG2 is a schematic diagram of electrical connections of the charging system 10 shown in FIG1 .

[0023] FIG3 is a schematic structural diagram of a power conversion device 111 provided in an embodiment of the present application.

[0024] FIG4 is a schematic diagram of vector operations provided in an embodiment of the present application.

[0025] FIG5 is a schematic flowchart of a leakage current detection method 500 applied to the aforementioned charging system, provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] To facilitate understanding, the terms involved in the embodiments of this application are first introduced.

[0027] 1. Circulating current: This refers to the current flowing between multiple power conversion devices connected in parallel. Because this current does not flow to the load or grid, it is called circulating current. Circulating current can include a low-frequency circulating current component and a high-frequency circulating current component. The low-frequency circulating current component has a lower current frequency than the high-frequency circulating current component.

[0028] 2. Three-phase alternating current: It can be an electric power system consisting of three alternating current circuits with the same frequency, equal potential amplitude and 120 degrees phase difference.

[0029] To facilitate understanding of the embodiments of the present application, the following points are explained before introducing the embodiments of the present application.

[0030] In the description of the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be achieved by direct or indirect connection to transmit signals between the two electrical components. For example, the connection between A and B can be understood as a direct connection between A and B, or it can be understood as an indirect connection between A and B through one or more other electrical components.

[0031] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in this article is merely a way to describe the association relationship of associated objects, indicating that three relationships can exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0032] In the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may judiciously or implicitly include one or more features. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two, and "at least one" and "one or more" refer to one, two or more. The singular expressions "a", "an", "said", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear indication to the contrary in the context.

[0033] The technical solution in this application will be described below with reference to the accompanying drawings.

[0034] First, to facilitate understanding of the power conversion device provided in the embodiments of the present application, the application scenarios of the power conversion device are introduced below.

[0035] FIG1 is a schematic structural diagram of a charging system 10 provided in an embodiment of the present application.

[0036] As shown in Figure 1, a charging system 10 may include a charging device 11 and a vehicle 12. The charging device 11 may include a power conversion device 111 and at least one charging terminal 112 connected to the power conversion device 111. Each of the at least one charging terminal 112 is connected to the vehicle 12. In a specific implementation, one charging terminal 112 may be connected to one vehicle 12, or multiple charging terminals 112 may be connected to one vehicle 12.

[0037] The power conversion device 111 can be used to receive AC power input from an external power grid and convert the AC power into stable DC power before transmitting it to the charging terminal 112. The charging terminal 112 can transmit the stable DC power converted by the power conversion device 111 to the vehicle 12 to charge the vehicle 12.

[0038] Optionally, the charging device 11 may be a charging pile, or may be other high-power charging equipment. It should be understood that the embodiment of the present application does not limit this.

[0039] FIG2 is a schematic diagram of electrical connections of the charging system 10 shown in FIG1 . As shown in FIG2 , the power conversion device 111 may include N AC-DC conversion circuits (eg, AC-DC conversion circuits 1111 to AC-DC conversion circuits 111n ) and a DC bus 114 .

[0040] It should be understood that the solid lines in Figure 2 represent power transmission lines. For example, the solid lines between the external power grid 20 and the N AC-DC conversion circuits (e.g., AC-DC conversion circuit 1111 to AC-DC conversion circuit 111n) in Figure 2 represent power transmission lines for the external power grid 20 to input alternating current to the N AC-DC conversion circuits.

[0041] Specifically, N AC-DC conversion circuits are connected in parallel, and the input ends of the N AC-DC conversion circuits can be connected to the external power grid 20, and the output ends of the N AC-DC conversion circuits can be connected to the DC bus 114. In other words, the N AC-DC conversion circuits can be connected in parallel between the external power grid 20 and the DC bus 114. The N AC-DC conversion circuits can be used to receive alternating current (AC) from the external power grid 20, convert the AC power into DC power, and output the DC power through the DC bus 114.

[0042] It should be noted that the power conversion device 111 can also be called an AC-DC conversion device or a rectifier cabinet. It should be understood that the embodiment of the present application is not limited to this.

[0043] Optionally, the charging device 11 may further include a DC-DC converter 113, wherein the input end of the DC-DC converter 113 may be connected to the DC bus 114, and the output end of the DC-DC converter 113 may be connected to the charging terminal 112. The DC-DC converter 113 may receive the DC power output by the power conversion device 111 via the DC bus 114, further convert the DC power into DC power suitable for the vehicle 12, and then transmit the DC power to the vehicle 12 via the charging terminal 112 for charging the vehicle 12.

[0044] Accordingly, the DC-DC converter device may also include N DC-DC converter circuits (e.g., DC-DC converter circuit 1131 to DC-DC converter circuit 113n), and the N DC-DC converter circuits are arranged in parallel in the DC-DC converter device 113. That is, the N DC-DC converter circuits 1131 are connected in parallel between the DC bus 114 and the charging terminal 112.

[0045] It should be noted that the charging terminal 112 may include a housing, a human-computer interaction interface, a charging control unit, and a metering and billing unit, etc. The charging terminal 112 may be used for information exchange, energy transmission, metering and billing, etc. with the vehicle 12 .

[0046] The vehicle 12 may be a vehicle powered by electricity. The vehicle 12 may be a new energy vehicle, such as a pure electric vehicle (pure EV / battery EV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), or a plug-in hybrid electric vehicle (PHEV).

[0047] In the power conversion device 111 , multiple AC-DC conversion circuits are connected in parallel, and each AC-DC conversion circuit performs power conversion processing on the AC power output from the external power grid 20 , thereby improving the AC-to-DC power conversion capability of the charging device 11 , thereby enabling the charging device 11 to charge the vehicle 12 at high power.

[0048] However, the AC-DC converter circuit in the power conversion device 111 is generally non-isolated, and circulating currents are easily generated between the N AC-DC converter circuits connected in parallel. Due to the existence of circulating currents, leakage protection cannot be provided on the unidirectional AC input side, and thus the power conversion device 111 cannot meet the requirements for personal electric shock protection or electrical fire protection.

[0049] Therefore, in scenarios where multiple high-power power conversion circuits are connected in parallel and the AC input has multiple AC circuits, how to perform leakage protection on the AC input side to meet the requirements of personal electric shock protection or electrical fire protection has become an urgent problem to be solved.

[0050] Based on this, an embodiment of the present application provides a power conversion device that can solve the leakage protection problem on the AC input side in a scenario where multiple high-power power conversion circuits are connected in parallel and the AC input has multiple circuits for AC power supply, so as to meet the requirements for personal electric shock protection or electrical fire protection.

[0051] FIG3 is a schematic structural diagram of a power conversion device 111 provided in an embodiment of the present application.

[0052] As shown in FIG3 , the power conversion device 111 may include N AC-DC conversion circuits (e.g., AC-DC conversion circuit 1111 to AC-DC conversion circuit 111n), N input power lines (e.g., input power line 1 to input power line n), and a detection device 115. The N AC-DC conversion circuits are connected in parallel.

[0053] Optionally, the N AC-DC conversion circuits are all non-isolated AC-DC conversion circuits.

[0054] Specifically, N input power lines correspond one-to-one to N AC-DC conversion circuits. For example, input power line 1 corresponds to AC-DC conversion circuit 1111, input power line 2 corresponds to AC-DC conversion circuit 1112, ..., and so on. Input power line n corresponds to AC-DC conversion circuit 111n.

[0055] The input end of each of the N AC-DC conversion circuits is connected to a corresponding input power line among the N input power lines, and is used to rectify the alternating current output from the corresponding input power line and output direct current.

[0056] It should be noted that the input ends of the N AC-DC conversion circuits can be connected to the external power grid, and the output ends of the N AC-DC conversion circuits can be connected to the DC bus 114. In other words, the N AC-DC conversion circuits are connected in parallel between the external power grid (not shown) and the DC bus 114. Optionally, the power conversion device 111 may further include an AC bus 116. In this case, the input ends of the N AC-DC conversion circuits may also be connected to the AC bus 116. In other words, the N AC-DC conversion circuits are connected in parallel between the AC bus 116 and the DC bus 114.

[0057] Continuing to refer to FIG. 3 , the detection device 115 includes a first port A1 and a second port A2 .

[0058] The detection device 115 obtains the leakage current of each of the N input power lines through the first port A1 and obtains the current or voltage of the i-th input power line through the second port A2. The detection device 115 then determines the leakage current of the power conversion device 111 based on the leakage current of each input power line and the current or voltage of the i-th input power line.

[0059] Specifically, the detection device 115 obtains the leakage current Ir1 on input power line 1 through the first port A1. The detection device 115 obtains the leakage current Ir2 on input power line 2 through the first port A1. Similarly, the detection device 115 obtains the leakage current Irn on input power line n through the first port A1. Furthermore, the detection device 115 obtains the current Ii or voltage Vi on the i-th input power line through the second port A2. Subsequently, the detection device 115 determines the leakage current of the power conversion device 111 based on the obtained leakage currents of the N input power lines and the current or voltage of the i-th input power line.

[0060] Exemplarily, the detection device 115 obtains leakage currents (e.g., Ir1, Ir2, ..., Irn) on N input power lines and the current Ii on the i-th input power line, and performs vector operations on the leakage currents (e.g., Ir1, Ir2, ..., Irn) and the current Ii on the i-th input power line to calculate the leakage current of the power conversion device 111. In other words, the total leakage current of the N input power lines can be obtained.

[0061] Exemplarily, the detection device 115 obtains leakage currents (e.g., Ir1, Ir2, ..., Irn) on N input power lines and a voltage Vi on the i-th input power line, and performs vector operations on the leakage currents (e.g., Ir1, Ir2, ..., Irn) and the voltage Vi on the i-th input power line to calculate the leakage current of the power conversion device 111. In other words, the total leakage current of the N input power lines can be obtained.

[0062] It should be noted that the detection device 115 obtains the leakage current of each input power line through the first port A1, which can be understood as the detection device 115 obtaining the leakage current of each input power line through the first port A1. The detection device 115 obtains the current or voltage of the i-th input power line among the N input power lines through the second port A2, which can be understood as the detection device 115 obtaining the current or voltage of the i-th input power line among the N input power lines through the second port A2.

[0063] Optionally, in the embodiment of the present application, the power conversion device 111 may further include N first sensors and N second sensors.

[0064] Specifically, the N first sensors correspond one-to-one to the N input power lines. For example, first sensor 1171 corresponds to input power line 1, first sensor 1172 corresponds to input power line 2, and so on. First sensor 117n corresponds to input power line n. Furthermore, the N first sensors are connected to first port A1. Each first sensor is configured to measure the leakage current of the corresponding input power line and output the current through first port A1. In this case, detection device 115 can obtain the leakage current of each input power line through first port A1.

[0065] The second sensor 118 is disposed on the i-th input power line and is connected to the second port A2. The second sensor 118 is configured to measure the voltage or current of the i-th input power line among the N input power lines and output the measured value through the second port A2. Furthermore, the detection device 115 can obtain the voltage or current of the i-th input power line through the second port A2.

[0066] Exemplarily, in one possible implementation, the first sensors (e.g., 1171 to 117n) and the second sensor 118 are both current sensors, which are used to collect the leakage current on the input power line and the current on the i-th input power line, respectively. Specifically, the detection device 115 obtains the leakage current (e.g., Ir1, Ir2, ... Irn) on the N input power lines through N first sensors, and obtains the current Ii on the i-th input power line through the second sensor 118. Vector operations are performed on the leakage current (e.g., Ir1, Ir2, ... Irn) and the current Ii on the i-th input power line to calculate the leakage current of the power conversion device 111. That is, the total leakage current of the N input power lines can be obtained.

[0067] Exemplarily, in one possible implementation, the first sensor (e.g., 1171 to 117n) is a current sensor for collecting leakage current on the input power line. The second sensor 118 is a voltage sensor for collecting the voltage value on the i-th input power line. Specifically, the detection device 115 obtains the leakage current (e.g., Ir1, Ir2, ... Irn) on the N input power lines through N first sensors, and obtains the voltage Vi on the i-th input power line through the second sensor 118. Vector operations are performed on the leakage current (e.g., Ir1, Ir2, ... Irn) and the voltage Vi on the i-th input power line to calculate the leakage current of the power conversion device 111. That is, the total leakage current of the N input power lines can be obtained.

[0068] It should be noted that the specific calculation process of performing vector operations on the leakage currents on the N input power lines and the current Ii or voltage Vi on the i-th input power line can refer to the existing technology and is not described here for simplicity.

[0069] It should be understood that when performing vector operations on the leakage currents on the N input power lines and the current Ii or voltage Vi on the i-th input power line, the current Ii or voltage Vi on the i-th input power line is used as a phase reference. FIG4 is a schematic diagram of vector operations provided in an embodiment of the present application.

[0070] For example, as shown in (a) and (b) of FIG4 , when performing vector operation to calculate the leakage current of the power conversion device 111 , the current I1 or the voltage V1 on the first input power line is selected as a phase reference.

[0071] Furthermore, in the embodiment of the present application, the detection device 115 is also used to control the N input power lines to be disconnected when the leakage current of the power conversion device 111 is greater than or equal to a set threshold.

[0072] Optionally, in the embodiment of the present application, the power conversion device 111 further includes N switching devices (not shown), and the N switching devices correspond one-to-one to the N input power lines. Each switching device is provided on the input power line corresponding to the switching device among the N input power lines, and each switching device is used to control the on / off of the corresponding input power line.

[0073] Specifically, when the detection device 115 detects that the leakage current of the power conversion device 111 is greater than or equal to a set threshold, the detection device 115 controls the switching devices on the N input power lines to be disconnected. The detection device 115 controls the switching devices on the N input power lines to be disconnected, which means that the detection device 115 controls the N input power lines to be disconnected.

[0074] It should be noted that the switching device mentioned above may include at least one of the following: a circuit breaker, an isolating switch, a relay, a contactor, an insulated gate bipolar transistor (IGBT), and a metal oxide semiconductor field effect transistor (MOSFIT). It should be understood that the embodiments of the present application are not limited to this.

[0075] For example, when the switching device includes a circuit breaker, in this embodiment of the present application, the detection device 115 controls all circuit breakers on the N input power lines to trip when the leakage current of the power conversion device 111 is greater than or equal to a set threshold. Tripping all circuit breakers can be understood as disconnecting the N input power lines.

[0076] Exemplarily, when the switching device includes an isolating switch, in an embodiment of the present application, the detection device 115 controls all the isolating switches on the N input power lines to be disconnected when the leakage current of the power conversion device 111 is greater than or equal to a set threshold.

[0077] It should be understood that the set threshold mentioned above is a current value set in advance.

[0078] According to the above technical solution, the detection device obtains the leakage current of N input power lines through the first port and the voltage or current of the i-th input power line through the second port. Based on the leakage current on each input power line and the voltage or current on the i-th input power line, a vector operation is performed to determine the leakage current of the power conversion device. Furthermore, if the leakage current is greater than or equal to a threshold, the N input power lines are controlled to disconnect, thereby resolving the leakage protection issue on the AC input side in AC power supply scenarios with multiple AC input circuits, and meeting requirements for personal electric shock protection or electrical fire protection.

[0079] FIG5 is a schematic flowchart of a leakage current detection method 500 applied to the aforementioned charging system provided in an embodiment of the present application. As shown in FIG5 , the method may include step S1 and step S2.

[0080] In step S510 , the detection device obtains the leakage current of each input power line through the first port, and obtains the current or voltage of the i-th input power line through the second port, where N is a positive integer and N≥2, 1≤i≤N.

[0081] Step S520 : The detection device determines the leakage current of the power conversion device according to the leakage current of each input power line and the current or voltage of the i-th input power line.

[0082] Specifically, the detection device obtains leakage current Ir1 on input power line 1 through the first port, obtains leakage current Ir2 on input power line 2 through the first port, and so on, obtaining leakage current Irn on input power line n through the first port. Furthermore, the detection device obtains current Ii or voltage Vi on the i-th input power line through the second port. Subsequently, the detection device determines the leakage current of the power conversion device based on the obtained leakage currents of the N input power lines and the current or voltage of the i-th input power line.

[0083] Exemplarily, the detection device obtains leakage currents (e.g., Ir1, Ir2, ..., Irn) on N input power lines and current Ii on the i-th input power line, and performs vector operations on the leakage currents (e.g., Ir1, Ir2, ..., Irn) and current Ii on the i-th input power line to calculate the leakage current of the power conversion device. In other words, the total leakage current of the N input power lines can be obtained.

[0084] Exemplarily, the detection device obtains leakage currents (e.g., Ir1, Ir2, ..., Irn) on N input power lines and a voltage Vi on the i-th input power line, and performs a vector operation on the leakage currents (e.g., Ir1, Ir2, ..., Irn) and the voltage Vi on the i-th input power line to calculate the leakage current of the power conversion device. In other words, the total leakage current of the N input power lines can be obtained.

[0085] It should be noted that the detection device obtains the leakage current of each input power line through the first port, which can be understood as the detection device obtaining the leakage current of each input power line through the first port. The detection device obtains the current or voltage of the i-th input power line among the N input power lines through the second port, which can be understood as the detection device obtaining the current or voltage of the i-th input power line among the N input power lines through the second port.

[0086] Optionally, in the embodiment of the present application, the power conversion device may further include N first sensors and N second sensors.

[0087] Specifically, the N first sensors correspond one-to-one to the N input power lines. For example, first sensor 1 corresponds to input power line 1, first sensor 2 corresponds to input power line 2, and so on. First sensor n corresponds to input power line n. Furthermore, the N first sensors are connected to the first port. Each first sensor is configured to measure the leakage current of a corresponding input power line among the N input power lines and output the current through the first port. In this case, the detection device can obtain the leakage current of each input power line through the first port.

[0088] A second sensor is provided on the i-th input power line and is connected to the second port. The second sensor is configured to measure the voltage or current of the i-th input power line among the N input power lines and output the voltage or current through the second port. Furthermore, the detection device can obtain the voltage or current of the i-th input power line through the second port.

[0089] Exemplarily, in one possible implementation, the first sensor and the second sensor are both current sensors, respectively used to collect leakage current on the input power line and current on the i-th input power line. Specifically, the detection device obtains leakage currents (e.g., Ir1, Ir2, ..., Irn) on N input power lines through the first sensor, and obtains current Ii on the i-th input power line through the second sensor, and performs vector operations on the leakage currents (e.g., Ir1, Ir2, ..., Irn) and current Ii on the i-th input power line to calculate the leakage current of the power conversion device. In other words, the total leakage current of the N input power lines can be obtained.

[0090] Exemplarily, in one possible implementation, the first sensor is a current sensor for collecting leakage current on the input power line. The second sensor is a voltage sensor for collecting the voltage value on the i-th input power line. Specifically, the detection device obtains the leakage current (e.g., Ir1, Ir2, ..., Irn) on N input power lines through the first sensor, and obtains the voltage Vi on the i-th input power line through the second sensor, and performs vector operation on the leakage current (e.g., Ir1, Ir2, ..., Irn) and the voltage Vi on the i-th input power line to calculate the leakage current of the power conversion device. In other words, the total leakage current of the N input power lines can be obtained.

[0091] It should be noted that the specific calculation process of performing vector operations on the leakage currents on the N input power lines and the current Ii or voltage Vi on the i-th input power line can refer to the existing technology and is not described here for simplicity.

[0092] It should be understood that when performing a vector operation on the leakage currents on the N input power lines and the current Ii or voltage Vi on the i-th input power line, the current Ii or voltage Vi on the i-th input power line is used as a phase reference. For example, as shown in (a) and (b) of FIG4 , when performing a vector operation to calculate the leakage current of the power conversion device, the current I1 or voltage V1 on the first input power line is used as a phase reference.

[0093] Optionally, in a possible implementation, the method may further include: step S530, when the leakage current of the power conversion device is greater than or equal to a set threshold, the detection device controls the N input power lines to be disconnected.

[0094] Optionally, in an embodiment of the present application, the power conversion device further includes N switching devices, and the N switching devices correspond one-to-one to the N input power lines. Each switching device is provided on the input power line corresponding to the switching device among the N input power lines, and each switching device is used to control the on / off of the corresponding input power line.

[0095] Specifically, when the leakage current of the power conversion device is greater than or equal to a set threshold, the detection device controls all the switch devices on the N input power lines to be disconnected. Controlling all the switch devices on the N input power lines to be disconnected by the detection device means controlling the N input power lines to be disconnected.

[0096] It should be noted that the switching device mentioned above may include at least one of the following: a circuit breaker, an isolating switch, a relay, a contactor, an IGBT, and a MOSFIT. It should be understood that the above is only an example and the embodiments of the present application do not limit this.

[0097] For example, when the switching device includes a circuit breaker, in an embodiment of the present application, the detection device controls the circuit breakers on N input power lines to trip when the leakage current of the power conversion device is greater than or equal to a set threshold. Tripping all the circuit breakers can be understood as disconnecting the N input power lines.

[0098] Exemplarily, when the switching device includes an isolating switch, in an embodiment of the present application, the detection device controls all the isolating switches on the N input power lines to be disconnected when the leakage current of the power conversion device is greater than or equal to a set threshold.

[0099] It should be understood that the set threshold mentioned above is a current value set in advance.

[0100] According to the above technical solution, the detection device obtains the leakage current of N input power lines through the first port and the voltage or current of the i-th input power line through the second port. Based on the leakage current on each input power line and the voltage or current on the i-th input power line, a vector operation is performed to determine the leakage current of the power conversion device. Furthermore, if the leakage current is greater than or equal to a threshold, the N input power lines are controlled to disconnect, thereby resolving the leakage protection issue on the AC input side in AC power supply scenarios with multiple AC input circuits, and meeting requirements for personal electric shock protection or electrical fire protection.

[0101] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A power conversion device, characterized in that: It includes N AC-DC conversion circuits, N input power lines and detection devices, The N AC-DC conversion circuits are connected in parallel, and the N input power lines correspond to the N power conversion circuits one by one, and each AC-DC conversion circuit is used to rectify the alternating current output from the corresponding input power line and output direct current; The detection device comprises a first port and a second port, and the detection device is used for: Obtain leakage currents of the N input power lines through the first port, and obtain current or voltage of the i-th input power line through the second port; Determining the leakage current of the power conversion device according to the leakage currents of the N input power lines and the current or voltage of the i-th input power line; Wherein, N is a positive integer, and N≥2, 1≤i≤N.

2. The power conversion device according to claim 1, characterized in that: The detection device is also used for: When the leakage current of the power conversion device is greater than or equal to a set threshold, the N input power lines are controlled to be disconnected.

3. The power conversion device according to claim 1 or 2, characterized in that: The power conversion device further comprises: N first sensors, corresponding one to one with the N input power lines, the N first sensors being connected to the first port, wherein each first sensor is used to measure and output a leakage current of a corresponding input power line among the N input power lines; The second sensor is arranged on the i-th input power line and connected to the second port, and is used for measuring the current or voltage of the i-th input power line and outputting it.

4. The power conversion device according to any one of claims 1 to 3, characterized in that: The detection device is specifically used for: Performing vector operation based on the leakage current of each input power line and the current or voltage of the i-th input power line to determine the leakage current of the power conversion device; The direction of the current or voltage of the i-th input power line is used as a phase reference when performing the vector operation.

5. The power conversion device according to any one of claims 1 to 4, characterized in that: Also includes: N switch devices, corresponding one to one with the N input power lines, wherein each switch device is arranged on a corresponding input power line among the N input power lines, and the switch device is used to control the on and off of the input power line; The detection device is specifically used for: When the leakage current of the power conversion device is greater than or equal to the set threshold, the N switch devices are controlled to be disconnected.

6. A charging device, characterized in that: The power conversion device comprises a power conversion device and at least one charging terminal, wherein the power conversion device is connected to the at least one charging terminal, and the power conversion device is used to receive alternating current input from an external power grid, and convert the alternating current into direct current and then output it to the at least one charging terminal. The power conversion device includes N AC-DC conversion circuits, N input power lines and a detection device, The N AC-DC conversion circuits are connected in parallel, and the N input power lines correspond to the N power conversion circuits one by one, and each AC-DC conversion circuit is used to rectify the alternating current output from the corresponding input power line and output direct current; The detection device comprises a first port and a second port, and the detection device is used for: Obtain leakage currents of the N input power lines through the first port, and obtain current or voltage of the i-th input power line through the second port; Determining the leakage current of the power conversion device according to the leakage currents of the N input power lines and the current or voltage of the i-th input power line; Wherein, N is a positive integer, and N≥2, 1≤i≤N.

7. The charging device according to claim 6, characterized in that: The detection device is also used for: When the leakage current of the power conversion device is greater than or equal to a set threshold, the N input power lines are controlled to be disconnected.

8. The charging device according to claim 6 or 7, characterized in that: The charging device also includes: N first sensors, corresponding one to one with the N input power lines, the N first sensors being connected to the first port, wherein each first sensor is used to measure and output a leakage current of a corresponding input power line among the N input power lines; The second sensor is arranged on the i-th input power line and connected to the second port, and is used for measuring the current or voltage of the i-th input power line and outputting it.

9. The charging device according to any one of claims 6 to 8, characterized in that: The detection device is specifically used for: Performing vector operation based on the leakage current of each input power line and the current or voltage of the i-th input power line to determine the leakage current of the power conversion device; The direction of the current or voltage of the i-th input power line is used as a phase reference when performing the vector operation.

10. The charging device according to any one of claims 6 to 9, characterized in that: The charging device also includes: N switch devices, corresponding one to one with the N input power lines, wherein each switch device is arranged on a corresponding input power line among the N input power lines, and the switch device is used to control the on and off of the input power line; The detection device is specifically used for: When the leakage current of the power conversion device is greater than or equal to the set threshold, the N switch devices are controlled to be disconnected.

Images