Detection circuit and power supply device for three-phase alternating current system

Abstract

The invention discloses a detection circuit for a three-phase alternating current system and a power supply device. A detection circuit for a three-phase AC system includes: a leakage current sensor configured to sense a leakage current in the three-phase AC system and generate a leakage current signal; the isolating switch circuit is electrically coupled with the output ends of a plurality of live wire relays and zero wire relays of the three-phase alternating current system; the voltage division detection circuit is electrically coupled with the isolation switch circuit, and the voltage division detection circuit is configured to perform voltage division on direct current voltage so as to output a voltage detection signal; the grounding switch circuit is electrically coupled with the partial voltage detection circuit; and a control module configured to control the isolation switch circuit and the grounding switch circuit to detect whether there is a fault in the three-phase AC system based on the leakage current signal or the voltage detection signal.

Description

Technical Field

[0001] The present application relates to the field of three-phase AC systems, and more specifically, to a detection circuit and a power supply device for a three-phase AC system. Background Art

[0002] In the application of three-phase alternative current (AC) charging piles, the process of charging from an AC charging pile to an electric device such as an electric vehicle can be started or ended by controlling the closing or disconnection of a relay in the three-phase AC system. This type of control method ensures safe, precise and efficient charging operations by controlling the action of the high-voltage circuit using a low-voltage signal to control the action of the relay. However, there may be faults in the three-phase AC system. For example, when trying to disconnect multiple live wire relays or neutral wire relays to stop the charging process, the relay cannot be completely disconnected (for example, adhesion occurs). This may cause the AC charging pile to fail to switch the working state normally, thereby affecting the stability and reliability of the charging pile. For example, there may be a short circuit fault between the live wires, between the live wire and the neutral wire, and between the live wire and the ground, which may damage or burn the electronic components inside the charging pile, and even cause safety hazards such as electric shock and burns. Summary of the invention

[0003] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

[0004] According to one aspect of the present invention, there is provided a detection circuit for a three-phase AC system, comprising: a leakage current sensor configured to sense leakage current in the three-phase AC system and generate a leakage current signal; an isolating switch circuit electrically coupled to output ends of a plurality of live wire relays and a neutral wire relay of the three-phase AC system; a voltage divider detection circuit electrically coupled to the isolating switch circuit, the voltage divider detection circuit being configured to divide a DC voltage to output a voltage detection signal; a grounding switch circuit electrically coupled to the voltage divider detection circuit; and a control module configured to control the isolating switch circuit and the grounding switch circuit to detect whether there is a fault in the three-phase AC system based on the leakage current signal or the voltage detection signal.

[0005] In the above-mentioned detection circuit, the voltage-dividing detection circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor and a fifth voltage-dividing resistor electrically coupled in series, wherein the first voltage-dividing resistor is electrically coupled to the second voltage-dividing resistor at a first node, the second voltage-dividing resistor is electrically coupled to the third voltage-dividing resistor at a second node, the third voltage-dividing resistor is electrically coupled to the fourth voltage-dividing resistor at a third node, and the fourth voltage-dividing resistor is electrically coupled to the fifth voltage-dividing resistor at a fourth node.

[0006] In the above-mentioned detection circuit, the isolation switch circuit includes: a first isolation switch, configured to receive a signal from the output end of the first live wire relay, the first isolation switch is electrically coupled in series with the first isolation resistor and is electrically coupled to the first node in the voltage divider detection circuit; a second isolation switch, configured to receive a signal from the output end of the second live wire relay, the second isolation switch is electrically coupled in series with the second isolation resistor and is electrically coupled to the second node in the voltage divider detection circuit; a third isolation switch, configured to receive a signal from the output end of the third live wire relay, the third isolation switch is electrically coupled in series with the third isolation resistor and is electrically coupled to the third node in the voltage divider detection circuit; and a fourth isolation switch, configured to receive a signal from the output end of the neutral wire relay, the fourth isolation switch is electrically coupled to the fourth node in the voltage divider detection circuit.

[0007] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit in a non-fully disconnected mode, and close one of the isolating switches in the isolating switch circuit, so as to detect whether there is a fault in the three-phase AC system based on the leakage current signal or the voltage detection signal; and put the grounding switch circuit in a fully disconnected mode, and close all the isolating switches in the isolating switch circuit, so as to detect whether there is a fault in the three-phase AC system based on the voltage detection signal.

[0008] In the above-mentioned detection circuit, the grounding switch circuit includes: a first grounding switch, electrically coupled to the first node in the voltage divider detection circuit; a second grounding switch, electrically coupled to the second node in the voltage divider detection circuit; and a third grounding switch, electrically coupled to the third node in the voltage divider detection circuit, wherein the control module is configured to obtain the voltage detection signal at the fourth node.

[0009] In the above-mentioned detection circuit, when at least one of the first grounding switch, the second grounding switch and the third grounding switch is configured to be closed, the grounding switch circuit is in the non-fully disconnected mode; when the first grounding switch, the second grounding switch and the third grounding switch are all configured to be disconnected, the grounding switch circuit is in the fully disconnected mode.

[0010] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit into the non-full disconnection mode, close the target isolating switch, and disconnect other isolating switches in the isolating switch circuit, wherein the target isolating switch is an isolating switch among the first isolating switch, the second isolating switch or the third isolating switch, which is connected to the same node in the voltage divider detection circuit as a closed grounding switch in the grounding switch circuit; and if it is determined that the leakage current signal is an alarm signal, it indicates that there is a fault in the three-phase AC system.

[0011] In the above detection circuit, the control module is configured to: place the grounding switch circuit in the full disconnection mode and disconnect all isolation switches in the isolation switch circuit; and determine the voltage detection signal as a reference voltage.

[0012] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit into the non-full disconnection mode, close the fourth isolating switch, and disconnect the other isolating switches in the isolating switch circuit; calculate the difference between the voltage detection signal and the reference voltage; and if it is determined that the difference is greater than or equal to a predetermined threshold, indicate that there is a fault in the three-phase AC system.

[0013] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit in the full disconnection mode and close all the isolating switches in the isolating switch circuit; calculate the difference between the voltage detection signal and the reference voltage; and if it is determined that the difference is greater than or equal to a predetermined threshold, indicate that there is a fault in the three-phase AC system.

[0014] In the above-mentioned detection circuit, the grounding switch circuit includes: a grounding switch, which is electrically coupled to the first node; wherein the voltage division detection circuit further includes: a first optocoupler module, the input end of the first optocoupler module is electrically coupled to the first node and the second node, and the output end of the first optocoupler module is configured to output a first optocoupler signal; a second optocoupler module, the input end of the second optocoupler module is electrically coupled to the second node and the third node, and the output end of the second optocoupler module is configured to output a second optocoupler signal; a third optocoupler module, the input end of the third optocoupler module is electrically coupled to the third node and the fourth node, and the output end of the third optocoupler module is configured to output a third optocoupler signal; a fourth optocoupler module, the input end of the fourth optocoupler module is electrically coupled to both ends of the fifth voltage-dividing resistor, and the output end of the fourth optocoupler module is configured to output a fourth optocoupler signal, wherein the voltage detection signal includes the first optocoupler signal, the second optocoupler signal, the third optocoupler signal and the fourth optocoupler signal.

[0015] In the above detection circuit, when the grounding switch is configured to be closed, the grounding switch circuit is in the non-fully disconnected mode; when the grounding switch is configured to be opened, the grounding switch circuit is in the fully disconnected mode.

[0016] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit in the full disconnection mode, and disconnect all the isolation switches in the isolation switch circuit; and if it is determined that the first optocoupler signal, the second optocoupler signal, the third optocoupler signal and the fourth optocoupler signal are at the first level, indicate that the detection circuit is working normally.

[0017] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit into the non-full disconnection mode, close the first isolating switch, and disconnect other isolating switches in the isolating switch circuit; and if it is determined that the leakage current signal is an alarm signal, it indicates that there is a fault in the three-phase AC system.

[0018] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit in the non-full disconnection mode, close the second isolating switch, the third isolating switch, and one of the fourth isolating switches, and disconnect the other isolating switches in the isolating switch circuit; and if it is determined that at least one of the first optocoupler signal, the second optocoupler signal, the third optocoupler signal, and the fourth optocoupler signal is at the first level, it indicates that there is a fault in the three-phase AC system.

[0019] In the above-mentioned detection circuit, the control module is configured to: put the grounding switch circuit in the full disconnection mode, and close all the isolating switches in the isolating switch circuit; and if it is determined that at least one of the first optocoupler signal, the second optocoupler signal, the third optocoupler signal and the fourth optocoupler signal is at the second level, it indicates that there is a fault in the three-phase AC system.

[0020] In the above detection circuit, the ratio of the voltage divider resistor to the isolation resistor is greater than or equal to 10:1.

[0021] According to another aspect of the present invention, a power supply device is provided, comprising: a plurality of live wire relays and neutral wire relays arranged on the live wire and neutral wire of a three-phase AC system; and a detection circuit as any one of the above detection circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention may be better understood by describing exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram showing the connection of a plurality of live relays and neutral relays for a three-phase AC system;

[0024] Figure 2 A block diagram of a detection circuit for a three-phase AC system according to an embodiment of the present invention is shown;

[0025] Figure 3 A schematic connection diagram of a detection circuit for a three-phase AC system according to an embodiment of the present invention is shown;

[0026] Figure 4A A flowchart showing operations performed by a control module according to one embodiment of the present invention is shown;

[0027] Figure 4B A flowchart showing operations performed by a control module according to another embodiment of the present invention is shown;

[0028] Figure 4C A flowchart showing operations performed by a control module according to yet another embodiment of the present invention;

[0029] Figure 5 A schematic connection diagram of a detection circuit for a three-phase AC system according to another embodiment of the present invention is shown;

[0030] Fig. 6A A flowchart showing operations performed by a control module according to yet another embodiment of the present invention;

[0031] Figure 6B A flowchart showing operations performed by a control module according to yet another embodiment of the present invention is shown;

[0032] Figure 6C A flowchart showing operations performed by a control module according to yet another embodiment of the present invention; and

[0033] Figure 7 A block diagram of a power supply device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto but only by the claims. In the accompanying drawings, for illustrative purposes, the sizes of some of the elements may be exaggerated and not drawn to scale. Wherever possible, the same reference numerals will be used in all drawings to represent the same or similar parts.

[0035] Although the terms used in the present invention are selected from well-known and commonly used terms, some of the terms mentioned in the present invention specification may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand the present invention not only by the actual terms used, but also by the meaning contained in each term.

[0036] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other examples, well-known methods, structures, and techniques are not shown in detail to avoid obscuring an understanding of the present invention.

[0037] Figure 1 A schematic diagram of the connection of multiple live relays and neutral relays for a three-phase AC system is shown. Multiple live relays and neutral relays are arranged in the main circuit of the AC charging pile. The input ends of the multiple live relays and neutral relays receive L1_IN, L2_IN, L3_IN and N_IN signals from the live wire and the neutral wire, respectively. When it is necessary to start the charging process, the multiple live relays and neutral relays are closed so that the L1_IN, L2_IN, L3_IN and N_IN signals can flow through each of the multiple live relays and the N-terminal relay, respectively, to be output as L1_OUT, L2_OUT, L3_OUT and N_OUT signals at the corresponding output ends; when it is necessary to stop the charging process, the multiple live relays and neutral relays are disconnected so that the L1_IN, L2_IN, L3_IN and N_IN signals cannot flow through.

[0038] However, if the live relay and the neutral relay are stuck or have other faults, the device containing the relay may be electrified, which may cause safety hazards such as electric shock, and even accelerate the aging and performance degradation of the components associated with the device, affecting the service life of the device. In addition, during the charging process for the device to be charged, excessive impact may be generated, thereby causing damage to the device to be charged, etc.

[0039] In addition, if a short circuit occurs between live wires, between live wire and neutral wire, or between live wire and ground, the current may increase sharply, further posing safety hazards such as electric shock. When a short circuit occurs, the large current generated releases a large amount of heat in a short period of time, and may even cause arc sparks, further leading to greater electrical safety risks.

[0040] Therefore, it is necessary to detect whether there is a fault in the three-phase AC system (for example, relay sticking, short circuit, etc.) in a suitable scenario.

[0041] In view of the above problems, the present application proposes a detection circuit for a three-phase AC system.

[0042] Figure 2 The block diagram of a detection circuit 200 for a three-phase AC system according to an embodiment of the present invention is shown. The detection circuit 200 may include a leakage current sensor 202, an isolation switch circuit 204, a voltage division detection circuit 206, a grounding switch circuit 208 and a control module 210.

[0043] The leakage current sensor 202 may be configured to sense leakage current in a three-phase AC system and generate a leakage current signal (abbreviated as a “TRIP signal”). The leakage current (i.e., residual current) refers to the current vector sum of each phase (including the neutral line) in the three-phase AC system that is not zero. The level of the TRIP signal may indicate whether there is leakage current.

[0044] The isolating switch circuit 204 can be electrically coupled to the output terminals of a plurality of live relays and a neutral relay of a three-phase AC system to receive a signal from the output terminal of each relay. In one embodiment, the isolating switch circuit 204 can include a first isolating switch, a second isolating switch, a third isolating switch, and a fourth isolating switch. The first isolating switch can be configured to receive a signal from the output terminal of the first live relay. The second isolating switch can be configured to receive a signal from the output terminal of the second live relay. The third isolating switch can be configured to receive a signal from the output terminal of the third live relay. The fourth isolating switch can be configured to receive a signal from the output terminal of the neutral relay.

[0045] By utilizing the isolating switch circuit, isolation between strong and weak electricity is achieved, and the safety and reliability of the system are improved with a relatively low increase in cost.

[0046] The voltage-dividing detection circuit 206 can be electrically coupled to the isolation switch circuit 204, and can be configured to divide the DC voltage to output a voltage detection signal. In one embodiment, the voltage-dividing detection circuit 206 may include a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor, and a fifth voltage-dividing resistor electrically coupled in series. The first voltage-dividing resistor can be electrically coupled to the second voltage-dividing resistor at a first node. The second voltage-dividing resistor can be electrically coupled to the third voltage-dividing resistor at a second node. The third voltage-dividing resistor can be electrically coupled to the fourth voltage-dividing resistor at a third node. The fourth voltage-dividing resistor can be electrically coupled to the fifth voltage-dividing resistor at a fourth node. By adopting such a simple voltage-dividing detection circuit, the circuit design cost is saved, and the complexity of debugging and calibration in the actual application process is reduced. In one embodiment, the DC voltage can be configured to 12V, 5V, etc.

[0047] Additionally, the first isolation switch included in the isolation switch circuit 204 can be electrically coupled in series with the first isolation resistor and electrically coupled with the first node in the voltage divider detection circuit 206. The second isolation switch can be electrically coupled in series with the second isolation resistor and electrically coupled with the second node in the voltage divider detection circuit 206. The third isolation switch can be electrically coupled in series with the third isolation resistor and electrically coupled with the third node in the voltage divider detection circuit 206. The fourth isolation switch can be electrically coupled with the fourth node in the voltage divider detection circuit. By electrically coupling the voltage divider detection circuit with the isolation switch circuit, the voltage divider detection circuit does not need to withstand strong electricity in certain operating modes, which reduces the selection requirements of the electronic components associated with it and reduces the difficulty of sampling the voltage detection signal.

[0048] The ground switch circuit 208 may be electrically coupled to the voltage division detection circuit 206. The ground switch circuit 208 may be controlled to be in different operation modes.

[0049] The control module 210 may be configured to control the isolation switch circuit 204 and the grounding switch circuit 208 to detect whether a fault exists in the three-phase AC system based on the TRIP signal or the voltage detection signal.

[0050] Since the isolation switch circuit and the grounding switch circuit can be controlled to switch multiple working modes, the detection requirements for multiple fault types can be met without designing independent detection circuits for each fault type. This significantly improves the versatility of the circuit, enabling it to flexibly respond to various fault types that may occur in a three-phase AC system. In addition, this design also effectively simplifies the circuit structure, reduces the occupied space and manufacturing cost, and avoids the complex connection and potential interference problems between multiple independent circuits, improving the robustness and reliability of the system.

[0051] In one embodiment, the control module 210 may be configured to place the grounding switch circuit 208 in a non-full disconnection mode and close an isolation switch in the isolation switch circuit 204 to detect whether there is a fault in the three-phase AC system based on a leakage current signal or a voltage detection signal.

[0052] In one embodiment, the control module 210 may be configured to place the grounding switch circuit 208 in the full disconnection mode and close all isolation switches in the isolation switch circuit 204 to detect whether there is a fault in the three-phase AC system based on the voltage detection signal.

[0053] In one embodiment, the ground switch circuit 208 may include a first ground switch, a second ground switch, and a third ground switch. Each of the ground switches may be electrically coupled to a first node, a second node, and a third node in the voltage divider detection circuit 206, respectively. The voltage detection signal may be output at a fourth node in the voltage divider detection circuit 206. In one embodiment, the ground switch may be a MOS tube.

[0054] Figure 3 A schematic connection diagram of a detection circuit 300 for a three-phase AC system according to an embodiment of the present invention is shown. As shown, the leakage current sensor may include a residual current device (RCD) surrounding live wires L1, L2, L3 and neutral wire N to sense leakage current.

[0055] The isolating switch circuit may include a first isolating switch K1, a second isolating switch K2, a third isolating switch K3 and a fourth isolating switch K4. The first isolating switch K1 is used to receive a signal L1_OUT from an output end of the first live relay S1. The second isolating switch K2 is used to receive a signal L2_OUT from an output end of the second live relay S2. The third isolating switch K3 is used to receive a signal L3_OUT from an output end of the third live relay S3. The fourth isolating switch K4 is used to receive a signal N_OUT from an output end of the neutral relay S4.

[0056] The voltage divider detection circuit is used to receive a DC voltage VDD. The voltage divider detection circuit may include a diode module VD1, a first voltage divider resistor R4, a second voltage divider resistor R5, a third voltage divider resistor R6, a fourth voltage divider resistor R7, and a fifth voltage divider resistor R8. The diode module VD1 may be electrically coupled in series with the first voltage divider resistor R4. The diode module VD1 serves to protect the components in the circuit from influences such as potential reverse electromotive force. Although Figure 3 The diode module VD1 is shown, but the diode module may be omitted from the circuit. The first voltage-dividing resistor R4 may be electrically coupled to the second voltage-dividing resistor R5 at a first node E1, the second voltage-dividing resistor R5 may be electrically coupled to the third voltage-dividing resistor R6 at a second node E2, the third voltage-dividing resistor R6 may be electrically coupled to the fourth voltage-dividing resistor R7 at a third node E3, and the fourth voltage-dividing resistor R7 may be electrically coupled to the fifth voltage-dividing resistor R8 at a fourth node E4.

[0057] The first isolation switch K1 may be electrically coupled in series with the first isolation resistor R1 and electrically coupled to the first node E1. The second isolation switch K2 may be electrically coupled in series with the second isolation resistor R2 and electrically coupled to the second node E2. The third isolation switch K3 may be electrically coupled in series with the third isolation resistor R3 and electrically coupled to the third node E3. The fourth isolation switch K4 may be electrically coupled to the fourth node E4. The voltage detection signal V_IN may be output at the fourth node E4.

[0058] The grounding switch circuit may include a first grounding switch Q1, a second grounding switch Q2, and a third grounding switch Q3. The first grounding switch Q1 may be electrically coupled to the first node E1 and grounded. The second grounding switch Q2 may be electrically coupled to the second node E2 and grounded, and the third grounding switch Q3 may be electrically coupled to the third node E3 and grounded.

[0059] The control module (not shown) is configured to control the isolation switches K1, K2, K3, K4 in the isolation switch circuit and the grounding switches Q1, Q2, Q3 in the grounding switch circuit to detect whether there is a fault in the three-phase AC system based on the TRIP signal or the voltage detection signal V_IN. In one embodiment, the control module may include a microcontroller and its peripheral circuit modules.

[0060] In one embodiment, when at least one of the first grounding switch, the second grounding switch, and the third grounding switch is configured to be closed, the grounding switch circuit is in a non-full disconnection mode. For example, when at least one of Q1, Q2, and Q3 is configured to be closed, the grounding switch circuit is in a non-full disconnection mode.

[0061] In one embodiment, when the first grounding switch, the second grounding switch and the third grounding switch are all configured to be disconnected, the grounding switch circuit is in the full disconnection mode. For example, when Q1, Q2 and Q3 are all configured to be disconnected, the grounding switch circuit is in the full disconnection mode.

[0062] In one embodiment, the control module may be configured to: put the grounding switch circuit in a full disconnection mode, disconnect all the isolation switches in the isolation switch circuit, and determine the voltage detection signal as a reference voltage. For example, the grounding switches Q1, Q2, and Q3 are all disconnected, and the isolation switches K1, K2, K3, and K4 are all disconnected, and the output voltage detection signal V_IN is determined as a reference voltage Vref.

[0063] In one embodiment, the control module may be further configured to: determine whether the reference voltage is within a predetermined range; and if the reference voltage is determined to be within the predetermined range, indicate that the detection circuit is operating normally. For example, when VDD is 12V and the values ​​of the voltage-dividing resistors R4, R5, R6, R7, and R8 are equal, the ideal voltage detection signal can be pre-calculated as 2.4V. Therefore, when the determined reference voltage Vref is within a predetermined range of 2.3V to 2.5V, the indication detection circuit is operating normally. For another example, when VDD is 5V and the values ​​of the voltage-dividing resistors R4, R5, R6, R7, and R8 are equal, the ideal voltage detection signal can be pre-calculated as 1V. Therefore, when the determined reference voltage Vref is within a predetermined range of 0.9V to 1.1V, the indication detection circuit is operating normally. Although the above predetermined range is offset by 0.1V based on the ideal voltage detection signal, the present invention is not limited thereto, for example, it can be offset by 0.01V, 0.05V, etc.

[0064] In one embodiment, the control module may be configured to: place the grounding switch circuit in a non-full disconnection mode and close an isolation switch in the isolation switch circuit to detect whether there is a fault in the three-phase AC system based on a leakage current signal or a voltage detection signal.

[0065] In one embodiment, the control module may be configured to place the grounding switch circuit in a full disconnection mode and close all isolation switches in the isolation switch circuit to detect whether there is a fault in the three-phase AC system based on the voltage detection signal.

[0066] It should be understood that the configuration of the above-mentioned mode for the grounding switch circuit and the configuration for the isolating switch circuit are not limited to being executed at the same time, but can be executed in sequence. In one embodiment, closing the grounding switch in the grounding switch circuit can occur before closing the isolating switch in the isolating switch circuit, that is, closing the grounding switch first and then closing the isolating switch. In addition, disconnecting the grounding switch in the grounding switch circuit can occur after disconnecting the isolating switch in the isolating switch circuit, that is, disconnecting the isolating switch first and then disconnecting the grounding switch. In this way, it is possible to prevent the impact of strong electricity on the detection circuit in the presence of a fault, which is conducive to improving the safety of the detection circuit.

[0067] In one embodiment, the ratio of each voltage-dividing resistor in the voltage-dividing detection circuit to each isolation resistor in the isolation switch circuit may be greater than or equal to 10:1.

[0068] By setting the ratio of the resistance value of the voltage divider resistor to the resistance value of the isolation resistor to be greater than or equal to 10:1, the voltage divider ratio can be controlled more accurately, so that the circuit can be adapted to different voltage input requirements while maintaining high measurement accuracy, thereby significantly improving the applicability of the circuit.

[0069] In one embodiment, the detection circuit 300 may further include a filtering circuit. The voltage detection signal V_IN that may be output at the fourth node E4 may be further transmitted through the filtering circuit (e.g., an RC filtering circuit) so that the control module can detect whether there is a fault in the three-phase AC system based on the filtered voltage detection signal.

[0070] Since the filtered voltage detection signal is smoother, reducing the influence of high-frequency fluctuations and noise, the detection accuracy of the control module is improved, and the complexity of the control module for processing is reduced. Figure 4A The flowchart of operation 400 performed by the control module according to an embodiment of the present invention is shown.

[0071] At step 402, the grounding switch circuit may be placed in a non-all-disconnected mode, the target disconnect switch may be closed, and the other disconnect switches in the disconnect switch circuit may be opened. The target disconnect switch may be one of the first disconnect switch, the second disconnect switch, and the third disconnect switch that is connected to the same node in the voltage division detection circuit as one of the closed grounding switches in the grounding switch circuit.

[0072] At step 404, it is determined whether the leakage current signal is an alarm signal. For example, if there is no leakage current in the three-phase AC system, the TRIP signal may be in a first state (e.g., low level). If there is a leakage current in the three-phase AC system, the TRIP signal may be in a second state (e.g., high level). The TRIP signal in the second state may be regarded as an alarm signal. Although the second state is described as high level here, it should be understood that in the case of using different types of leakage current sensors, the first state and the second state may also correspond to high level and low level respectively.

[0073] If it is determined at step 404 that the leakage current signal is an alarm signal (e.g., the leakage current signal is high level), then at step 406, it is indicated that there is a fault in the three-phase AC system.

[0074] If it is determined at step 404 that the leakage current signal is not an alarm signal (e.g., the leakage current signal is low level), then at step 408, it is indicated that there is no fault in the three-phase AC system.

[0075] For example, in some cases, referring to Figure 3, the control module can be configured to: close any one of the first grounding switch Q1, the second grounding switch Q2, or the third grounding switch Q3 in the grounding switch circuit or any combination thereof (including but not limited to closing Q1 and Q2, closing Q1 and Q3, closing Q2 and Q3, closing Q1, Q2, and Q3), closing the first isolating switch K1, and opening the second isolating switch K2, the third isolating switch K3, and the fourth isolating switch K4. Then, read the TRIP signal generated by the leakage current sensor RCD. If it is determined that the TRIP signal is an alarm signal, it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the first live wire relay S1. If it is determined that the TRIP signal is not an alarm signal, it indicates that there is no fault in the three-phase AC system.

[0076] For example, in some cases, reference Figure 3 , the control module can be configured to: close any one of the first grounding switch Q1, the second grounding switch Q2, or the third grounding switch Q3 in the grounding switch circuit or any combination thereof (including but not limited to closing Q1 and Q2, closing Q1 and Q3, closing Q2 and Q3, closing Q1, Q2, and Q3), closing the second isolating switch K2, and opening the first isolating switch K1, the third isolating switch K3, and the fourth isolating switch K4. Then, read the TRIP signal generated by the leakage current sensor RCD. If it is determined that the TRIP signal is an alarm signal, it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the second live wire relay S2. If it is determined that the TRIP signal is not an alarm signal, it indicates that there is no fault in the three-phase AC system.

[0077] For example, in some cases, reference Figure 3 , the control module can be configured to: close any one of the first grounding switch Q1, the second grounding switch Q2, or the third grounding switch Q3 in the grounding switch circuit or any combination thereof (including but not limited to closing Q1 and Q2, closing Q1 and Q3, closing Q2 and Q3, closing Q1, Q2, and Q3), closing the third isolating switch K3, and opening the first isolating switch K1, the second isolating switch K2, and the fourth isolating switch K4. Then, read the TRIP signal generated by the leakage current sensor RCD. If it is determined that the TRIP signal is an alarm signal, it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the third live wire relay S3. If it is determined that the TRIP signal is not an alarm signal, it indicates that there is no fault in the three-phase AC system.

[0078] Figure 4B A flow chart showing operations 410 performed by a control module according to another embodiment of the present invention is shown.

[0079] At step 412, the earthing switch circuit can be placed in a non-fully open mode, and the fourth isolating switch is closed.

[0080] At step 414, it is determined whether the difference between the voltage detection signal and the reference voltage is greater than or equal to a predetermined threshold.

[0081] If at step 414 it is determined that the difference between the voltage detection signal and the reference voltage is greater than or equal to the predetermined threshold, then at step 416 it is indicated that there is a fault in the three-phase AC system.

[0082] If at step 414 it is determined that the difference between the voltage detection signal and the reference voltage is less than the predetermined threshold, then at step 418 it is indicated that there is no fault in the three-phase AC system.

[0083] For example, in some cases, with reference to Figure 3 , the control module can be configured to: close any one of the first earthing switch Q1, the second earthing switch Q2, or the third earthing switch Q3 in the earthing switch circuit or any combination thereof (including but not limited to closing Q1 and Q2, closing Q1 and Q3, closing Q2 and Q3, closing Q1, Q2, and Q3), close the fourth isolating switch K4, and open the first isolating switch K1, the second isolating switch K2, and the third isolating switch K3. Then, calculate the difference between the voltage detection signal V_IN and the reference voltage Vref. If it is determined that the difference is greater than or equal to the predetermined threshold Vth, then it is indicated that there is a fault in the three-phase AC system, for example, the neutral line relay S4 has an adhesion fault. If it is determined that the difference is less than the predetermined threshold Vth, then it is indicated that there is no fault in the three-phase AC system. The reference voltage Vref can be measured at the fourth node E4 when Q1, Q2, and Q3 are all open, and the first isolating switch K1, the second isolating switch K2, the third isolating switch K3, and the fourth isolating switch K4 are all open. The predetermined threshold Vth can be pre-determined by the control module.

[0084] In some embodiments, when VDD is 12V and the values of the first voltage-dividing resistor R4, the second voltage-dividing resistor R5, the third voltage-dividing resistor R6, the fourth voltage-dividing resistor R7, and the fifth voltage-dividing resistor R8 are equal, the measured ideal reference voltage Vref can be 2.4V, and the predetermined threshold Vth can be pre-determined as 0.2V.

[0085] Although in the above example the predetermined threshold Vth is set to 0.2V, the present invention is not limited thereto. For example, the predetermined threshold Vth can be set to, for example, 0.1V, 0.3V, 0.4V, etc.

[0086] In some embodiments, when VDD is 5V and the values ​​of the first voltage-dividing resistor R4, the second voltage-dividing resistor R5, the third voltage-dividing resistor R6, the fourth voltage-dividing resistor R7 and the fifth voltage-dividing resistor R8 are equal, the measured ideal reference voltage Vref can be 1V, and the predetermined threshold value Vth can be predetermined to 0.1V.

[0087] Although the predetermined threshold value Vth is set to 0.1V in the above example, the present invention is not limited thereto, and for example, the predetermined threshold value Vth may be set to 0.08V, 0.12V, 0.15V, etc., for example.

[0088] Figure 4C A flow chart showing operations 420 performed by a control module according to yet another embodiment of the present invention is shown.

[0089] At step 422 , the grounding switch circuit may be placed in an all-open mode and all isolation switches may be closed.

[0090] At step 424 , it is determined whether the difference between the voltage detection signal and the reference voltage is greater than or equal to a predetermined threshold.

[0091] If it is determined at step 424 that the difference between the voltage detection signal and the reference voltage is greater than or equal to the predetermined threshold, then at step 426 it is indicated that a fault exists in the three-phase AC system.

[0092] If it is determined at step 424 that the difference between the voltage detection signal and the reference voltage is less than the predetermined threshold, then at step 428 it is indicated that there is no fault in the three-phase AC system.

[0093] For example, in some cases, reference Figure 3 , the control module can be configured to: disconnect the first grounding switch Q1, the second grounding switch Q2, and the third grounding switch Q3 in the grounding switch circuit, and close the first isolating switch K1, the second isolating switch K2, the third isolating switch K3, and the fourth isolating switch K4. Then, the difference between the voltage detection signal V_IN and the reference voltage Vref is calculated. If it is determined that the difference is greater than or equal to the predetermined threshold value Vth, it indicates that there is a fault in the three-phase AC system. For example, any of the following faults may exist: a short circuit between multiple live wires, a short circuit between any one of the multiple live wires and the neutral wire, and a short circuit between any one of the multiple live wires and the ground. If it is determined that the difference is less than the predetermined threshold value Vth, it indicates that there is no fault in the three-phase AC system. The reference voltage Vref can be measured at the fourth node E4 when Q1, Q2, and Q3 are all disconnected, and the first isolating switch K1, the second isolating switch K2, the third isolating switch K3, and the fourth isolating switch K4 are all disconnected. The predetermined threshold value Vth can be predetermined by the control module.

[0094] In some embodiments, when VDD is 12V and the values ​​of the first voltage-dividing resistor R4, the second voltage-dividing resistor R5, the third voltage-dividing resistor R6, the fourth voltage-dividing resistor R7 and the fifth voltage-dividing resistor R8 are equal, the ideal reference voltage Vref can be predetermined to be 2.4V. In this case, if the first isolation resistor R1, the second isolation resistor R2 and the third isolation resistor R3 are equal, and the ratio of the voltage-dividing resistor to the isolation resistor is 10:1, the ideal difference of the voltage detection signal V_IN corresponding to different fault types relative to the reference voltage Vref is shown in Table 1 below:

[0095]

[0096] Table 1

[0097] Since the minimum value of the above difference is 0.46V, the predetermined threshold value Vth can be set to 0.2V.

[0098] Although the predetermined threshold value Vth may be set to 0.2V in the above example, the present invention is not limited thereto, and for example, the predetermined threshold value Vth may be set to 0.1V, 0.3V, 0.4V, etc., for example.

[0099] In some embodiments, when VDD is 5V and the values ​​of the first voltage-dividing resistor R4, the second voltage-dividing resistor R5, the third voltage-dividing resistor R6, the fourth voltage-dividing resistor R7 and the fifth voltage-dividing resistor R8 are equal, the ideal reference voltage Vref may be predetermined to be 1V. In this case, if the first isolation resistor R1, the second isolation resistor R2 and the third isolation resistor R3 are equal, and the ratio of the voltage-dividing resistor to the isolation resistor is 10:1, the ideal difference of the voltage detection signal V_IN corresponding to different fault types relative to the reference voltage Vref is shown in Table 2 below:

[0100]

[0101]

[0102] Table 2

[0103] Since the minimum value of the above difference is 0.19V, the predetermined threshold value Vth can be set to 0.1V.

[0104] Although the predetermined threshold value Vth may be set to 0.1V in the above example, the present invention is not limited thereto, and for example, the predetermined threshold value Vth may be set to 0.08V, 0.12V, 0.15V, etc.

[0105] Therefore, by using multiple voltage-dividing resistors for voltage division, in addition to being able to detect whether there is a fault in the three-phase AC system, it is even possible to determine different short-circuit types in the three-phase AC system and detect whether there is a fault such as neutral line relay adhesion.

[0106] return Figure 2 In another embodiment, the grounding switch circuit 208 may include a grounding switch. The grounding switch may be electrically coupled to the first node in the voltage divider detection circuit 206. The voltage divider detection circuit may further include a first optical coupling module, a second optical coupling module, a third optical coupling module, and a fourth optical coupling module. The input end of the first optical coupling module may be electrically coupled to the first node and the second node in the voltage divider detection circuit 206, and the output end of the first optical coupling module may be configured to output a first optical coupling signal. The input end of the second optical coupling module may be electrically coupled to the second node and the third node in the voltage divider detection circuit 206, and the output end of the second optical coupling module may be configured to output a second optical coupling signal. The input end of the third optical coupling module may be electrically coupled to the third node and the fourth node in the voltage divider detection circuit 206, and the output end of the third optical coupling module may be configured to output a third optical coupling signal. The input end of the fourth optical coupling module may be electrically coupled to both ends of the fifth voltage divider resistor, and the output end of the fourth optical coupling module may be configured to output a fourth optical coupling signal. The voltage detection signal may include a first optical coupling signal, a second optical coupling signal, a third optical coupling signal, and a fourth optical coupling signal. In one embodiment, the grounding switch may be a MOS tube. In one embodiment, the optical coupling module may be a bidirectional optical coupling module.

[0107] Figure 5 FIG. 5 shows a schematic connection diagram of a detection circuit 500 for a three-phase AC system according to another embodiment of the present invention. Figure 5 The specific structure and connection relationship of the leakage current sensor and isolation switch circuit in Figure 3 The specific structures and connection relationships of the leakage current sensor and the isolation switch circuit are similar. For the sake of clarity, the repeated parts will not be repeated here.

[0108] As shown in the figure, the voltage divider detection circuit is used to receive the DC voltage VDD. The voltage divider detection circuit may include a diode module VD1, a first voltage divider resistor R4, a second voltage divider resistor R5, a third voltage divider resistor R6, a fourth voltage divider resistor R7 and a fifth voltage divider resistor R8. The diode module VD1 may be electrically coupled in series with the first voltage divider resistor R4. The diode module VD1 serves to protect the components in the circuit from influences such as potential reverse electromotive force. Although Figure 5The diode module VD1 is shown, but the diode module can also be omitted from the circuit. The first voltage-dividing resistor R4 can be electrically coupled to the second voltage-dividing resistor R5 at the first node E1, the second voltage-dividing resistor R5 can be electrically coupled to the third voltage-dividing resistor R6 at the second node E2, the third voltage-dividing resistor R6 can be electrically coupled to the fourth voltage-dividing resistor R7 at the third node E3, and the fourth voltage-dividing resistor R7 can be electrically coupled to the fifth voltage-dividing resistor R8 at the fourth node E4. Figure 3 The connection relationship between the isolation switch circuit and the voltage division detection circuit has been described, and will not be repeated here to avoid redundancy.

[0109] The voltage-dividing detection circuit may further include a first optical coupling module U1, a second optical coupling module U2, a third optical coupling module U3, and a fourth optical coupling module U4. The input end of the first optical coupling module U1 may be electrically coupled to the first node E1 and the second node E2, and the output end of the first optical coupling module U1 may be configured to output a first optical coupling signal V1_IN. The input end of the second optical coupling module U2 may be electrically coupled to the second node E2 and the third node E3, and the output end of the second optical coupling module U2 may be configured to output a second optical coupling signal V2_IN. The input end of the third optical coupling module U3 may be electrically coupled to the third node E3 and the fourth node E4, and the output end of the third optical coupling module U3 may be configured to output a third optical coupling signal V3_IN. The input end of the fourth optical coupling module U4 may be electrically coupled to both ends of the fifth voltage-dividing resistor R8, and the output end of the fourth optical coupling module U4 may be configured to output a fourth optical coupling signal V4_IN. The voltage detection signal may include a first optocoupler signal V1_IN, a second optocoupler signal V2_IN, a third optocoupler signal V3_IN, and a fourth optocoupler signal V4_IN. The first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN may be electrically coupled to the ground through capacitors C1, C2, C3, and C4, respectively. Capacitors C1, C2, C3, and C4 play a filtering role. Although Figure 5 Capacitors C1, C2, C3, C4 are shown, but they may be omitted from the circuit.

[0110] The ground switch circuit may include a ground switch Q1 , which may be electrically coupled to the first node E1 and grounded.

[0111] The control module (not shown) is configured to control the isolation switches K1, K2, K3, K4 in the isolation switch circuit and the grounding switch Q1 in the grounding switch circuit to detect whether there is a fault in the three-phase AC system based on the TRIP signal or the voltage detection signals V1_IN, V2_IN, V3_IN and V4_IN. In one embodiment, the control module may include a microcontroller and its peripheral circuit modules.

[0112] In one embodiment, when the grounding switch is configured to be closed, the grounding switch circuit is in a non-fully open mode. For example, when Q1 is configured to be closed, the grounding switch circuit is in a non-fully open mode.

[0113] In one embodiment, when the grounding switch is configured to be turned off, the grounding switch circuit is in the full-off mode. For example, when Q1 is configured to be turned off, the grounding switch circuit is in the full-off mode.

[0114] In one embodiment, the control module is configured to: put the grounding switch circuit in a full disconnection mode, and disconnect all the isolation switches in the isolation switch circuit, and if it is determined that the first optocoupler signal, the second optocoupler signal, the third optocoupler signal, and the fourth optocoupler signal are at the first level, then the detection circuit is indicated to work normally. For example, the control module is configured to disconnect Q1, and disconnect the first isolation switch K1, the second isolation switch K2, the third isolation switch K3, and the fourth isolation switch K4. If it is determined that the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN are all at the first level (i.e., low level), then the detection circuit 500 is indicated to work normally. If it is determined that at least one of the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN is at the second level (i.e., high level), then the detection circuit 500 is indicated to be faulty.

[0115] In one embodiment, the control module may be configured to: place the grounding switch circuit in a non-full disconnection mode and close an isolation switch in the isolation switch circuit to detect whether there is a fault in the three-phase AC system based on a leakage current signal or a voltage detection signal.

[0116] In one embodiment, the control module may be configured to place the grounding switch circuit in a full disconnection mode and close all isolation switches in the isolation switch circuit to detect whether there is a fault in the three-phase AC system based on the voltage detection signal.

[0117] It should be understood that the configuration of the above-mentioned mode for the grounding switch circuit and the configuration for the isolating switch circuit are not limited to being executed at the same time, but can be executed in sequence. In one embodiment, closing the grounding switch in the grounding switch circuit can occur before closing the isolating switch in the isolating switch circuit, that is, closing the grounding switch first and then closing the isolating switch. In addition, disconnecting the grounding switch in the grounding switch circuit can occur after disconnecting the isolating switch in the isolating switch circuit, that is, disconnecting the isolating switch first and then disconnecting the grounding switch. In this way, it is possible to prevent the impact of strong electricity on the detection circuit in the presence of a fault, which is conducive to improving the safety of the detection circuit.

[0118] In one embodiment, the ratio of each voltage-dividing resistor in the voltage-dividing detection circuit to each isolation resistor in the isolation switch circuit may be greater than or equal to 10:1.

[0119] By setting the ratio of the resistance value of the voltage divider resistor to the resistance value of the isolation resistor to be greater than or equal to 10:1, the voltage divider ratio can be controlled more accurately, so that the circuit can be adapted to different voltage input requirements while maintaining high measurement accuracy, thereby significantly improving the applicability of the circuit.

[0120] In one embodiment, the detection circuit 500 may further include a filtering circuit. The voltage detection signals V1_IN, V2_IN, V3_IN, and V4_IN at the output of each optocoupler module may be further transmitted through a filtering circuit (e.g., an RC filtering circuit), so that the control module detects whether there is a fault in the three-phase AC system based on the filtered voltage detection signals.

[0121] Since the filtered voltage detection signal is more stable, the influence of high-frequency fluctuations and noise is reduced, the detection accuracy of the control module is improved, and the complexity of the processing performed by the control module is reduced.

[0122] Fig. 6A A flow chart illustrating operations 600 performed by a control module according to yet another embodiment of the present invention.

[0123] At step 602 , the grounding switch circuit may be placed in a non-full disconnect mode, a first isolating switch may be closed, and other isolating switches in the isolating switch circuit may be opened.

[0124] At step 604, it is determined whether the leakage current signal is an alarm signal. For example, if there is no leakage current in the three-phase AC system, the TRIP signal may be in a first state (e.g., a low level). If there is leakage current in the three-phase AC system, the TRIP signal may be in a second state (e.g., a high level). The TRIP signal in the second state may be considered an alarm signal. Although the second state is described as a high level here, it should be understood that in the case of using different types of leakage current sensors 202, the first state and the second state may also correspond to a high level and a low level, respectively.

[0125] If it is determined at step 604 that the leakage current signal is an alarm signal (eg, a high level), then at step 606 it is indicated that there is a fault in the three-phase AC system.

[0126] If it is determined at step 604 that the leakage current signal is not an alarm signal (eg, a low level), then at step 608 it is indicated that there is no fault in the three-phase AC system.

[0127] For example, in some cases, reference Figure 5 , the control module can be configured to: close the grounding switch Q1, close the first isolating switch K1, and open the second isolating switch K2, the third isolating switch K3, and the fourth isolating switch K4 in the isolating switch circuit. Then, read the TRIP signal generated by the leakage current sensor RCD. If it is determined that the TRIP signal is an alarm signal, it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the first live wire relay S1. If it is determined that the TRIP signal is not an alarm signal, it indicates that there is no fault in the three-phase AC system.

[0128] Figure 6B A flow chart showing operations 610 performed by a control module according to yet another embodiment of the present invention is shown.

[0129] At step 612 , the grounding switch circuit may be placed in a non-full disconnection mode, one of the second isolating switch, the third isolating switch, and the fourth isolating switch may be closed, and the other isolating switches in the isolating switch circuit may be opened.

[0130] At step 614 , it is determined whether at least one of the first to fourth optocoupler signals is at a first level.

[0131] If it is determined at step 614 that at least one of the first to fourth optocoupler signals is at a first level (eg, a low level), then at step 616 it is indicated that there is a fault in the three-phase AC system.

[0132] If it is determined at step 614 that the first to fourth optocoupler signals are all at the second level (eg, high level), then at step 618 it is indicated that there is no fault in the three-phase AC system.

[0133] For example, in some cases, reference Figure 5 , the control module can be configured to: close the grounding switch Q1 in the grounding switch circuit, close the second isolating switch K2, and open the first isolating switch K1, the third isolating switch K3, and the fourth isolating switch K4. Then, if it is determined that at least one of the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN is at the first level (i.e., low level), it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the second live wire relay S2. If it is determined that the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN are all at the second level (i.e., high level), it indicates that there is no fault in the three-phase AC system.

[0134] For example, in some cases, reference Figure 5, the control module can be configured to: close the grounding switch Q1 in the grounding switch circuit, close the third isolating switch K3, and open the first isolating switch K1, the second isolating switch K2, and the fourth isolating switch K4. Then, if it is determined that at least one of the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN is at the first level (i.e., low level), it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the third live wire relay S3. If it is determined that the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN are all at the second level (i.e., high level), it indicates that there is no fault in the three-phase AC system.

[0135] For example, in some cases, reference Figure 5 , the control module can be configured to: close the grounding switch Q1 in the grounding switch circuit, close the fourth isolating switch K4, and open the first isolating switch K1, the second isolating switch K2, and the third isolating switch K3. Then, if it is determined that at least one of the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN is at a first level (i.e., a low level), it indicates that there is a fault in the three-phase AC system, for example, there is a sticking fault in the neutral relay S4. If it is determined that the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN are all at a second level (i.e., a high level), it indicates that there is no fault in the three-phase AC system.

[0136] Figure 6C A flow chart illustrating operations 620 performed by a control module according to yet another embodiment of the present invention.

[0137] At step 622 , the grounding switch circuit may be placed in an all-open mode and all isolation switches may be closed.

[0138] At step 624 , it is determined whether at least one of the first to fourth optocoupler signals is at a second level (eg, a high level).

[0139] If it is determined at step 624 that at least one of the first to fourth optocoupler signals is at the second level (eg, a high level), then at step 626 it is indicated that there is a fault in the three-phase AC system.

[0140] If it is determined at step 624 that the first to fourth optocoupler signals are all at the first level (eg, low level), then at step 628 it is indicated that there is no fault in the three-phase AC system.

[0141] For example, in some cases, reference Figure 5 The control module can be configured to: open the grounding switch Q1 in the grounding switch circuit, and close all of the first disconnecting switch K1, the second disconnecting switch K2, the third disconnecting switch K3, and the fourth disconnecting switch K4. Then, read the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN. If it is determined that at least one of the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN is at the second level (i.e., high level), it indicates that there is a fault in the three-phase AC system. For example, any one of the following faults may exist: a short circuit between multiple live wires, a short circuit between any one of the multiple live wires and the neutral wire, or a short circuit between any one of the multiple live wires and the ground. If it is determined that the first optocoupler signal V1_IN, the second optocoupler signal V2_IN, the third optocoupler signal V3_IN, and the fourth optocoupler signal V4_IN are all at the first level (i.e., low level), it indicates that there is no fault in the three-phase AC system.

[0142] Figure 7 The block diagram of a power supply device 700 according to an embodiment of the present invention is shown. The power supply device 700 may include: a plurality of live wire relays (the first live wire relay, the second live wire relay, the third live wire relay) and a neutral wire relay provided on the live wires and the neutral wire in the three-phase AC system; and a detection circuit 702. The detection circuit 702 may be the detection circuit 200 in Figure 2 . The input ends of the plurality of live wire relays and the neutral wire relay are respectively used to receive the L1_IN, L2_IN, L3_IN, and N_IN signals from the live wires and the neutral wire. In a suitable scenario, the L1_IN, L2_IN, L3_IN signals, the N_IN signal, and the L1_OUT, L2_OUT, L3_OUT signals, and the N_OUT signals at the corresponding output ends are used to detect whether the live wire relays and / or the neutral wire relay are stuck and / or whether there is a short circuit fault between the live wires, between the live wire and the neutral wire, or between the live wire and the ground. For example, if any one of the above faults or any combination thereof exists, it indicates that there is a fault in the three-phase AC system, thereby deactivating the power supply device 700. For another example, if none of the above faults exist, the power supply device 700 may be enabled to charge the device to be charged. In one embodiment, the device to be charged may be an electric vehicle. In one embodiment, the power supply device 700 may be a charging pile.

[0143] By deactivating the power supply device 700 in the event of the above faults, potential safety hazards during the charging process are avoided, ensuring the safety of the power supply device for power supply.

[0144] In one embodiment, when the device to be charged is disconnected from the power supply device 700, the detection circuit may be configured to detect whether there is a fault in the three-phase AC system. For example, when the power supply device is installed, the detection circuit may be configured to detect whether there is a fault in the three-phase AC system. For another example, before the device to be charged is electrically coupled to the power supply device to start the charging process, the detection circuit may be configured to detect whether there is a fault in the three-phase AC system. For another example, after the device to be charged that has completed charging is electrically decoupled from the power supply device to stop the charging process, the detection circuit may be configured to detect whether there is a fault in the three-phase AC system.

[0145] In one embodiment, the detection circuit can be configured to periodically detect whether there is a fault in the three-phase AC system. The detection period and the number of detections can be set by the control module. For example, if the detection period is set to seven days and the number of detections is set to three times, then the detection of whether there is a fault in the three-phase AC system is performed three times every seven days.

[0146] In another embodiment, the detection circuit can be configured to perform detection on demand, such as before and after charging.

[0147] By detecting whether there is a fault in the three-phase AC system according to needs or in appropriate scenarios, the detection circuit can be actively controlled to be enabled or disabled, reducing system power consumption and extending the service life of the system. By setting the detection timing, detection cycle, detection times, etc. according to needs, the flexibility of the system is greatly enhanced.

[0148] The detection circuit and power supply device for three-phase AC according to the exemplary embodiment of the present application are described above. By utilizing the isolating switch circuit, isolation between strong and weak electricity is achieved, and the safety and reliability of the system are improved at a low cost increase. By electrically coupling the voltage-dividing detection circuit with the isolating switch circuit, the voltage-dividing detection circuit does not need to withstand strong electricity in certain working modes, reducing the selection requirements of the electronic components associated therewith, and reducing the difficulty of sampling the voltage detection signal. Since the isolating switch circuit and the grounding switch circuit can be controlled to switch a variety of working modes, the detection requirements for a variety of fault types can be met without designing a separate detection circuit for each fault type. This significantly improves the versatility of the circuit, enabling it to flexibly respond to various fault types that may occur in a three-phase AC system. In addition, this design also effectively simplifies the circuit structure, reduces the occupied space and manufacturing cost, and avoids the complex connection and potential interference problems between multiple independent circuits, improving the robustness and reliability of the system.

[0149] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification are not necessarily all references to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be apparent to one of ordinary skill in the art from this disclosure, the particular features, structures, or characteristics may be combined in any suitable manner.

[0150] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects, the various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Therefore, the claims appended hereto are hereby expressly incorporated into this detailed description, with each claim itself representing a separate embodiment of the invention.

[0151] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in other embodiments, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0152] As used herein, module refers to any combination of hardware, software, and / or firmware. As an example, a module includes hardware such as a microcontroller associated with a non-transient medium, and the non-transient medium is used to store a code suitable for being executed by the microcontroller. Therefore, in one implementation, reference to a module refers to hardware that is specifically configured to identify and / or execute code to be stored on a non-transient medium. In addition, in another implementation, the use of a module refers to a non-transient medium including a code that is specifically suitable for being executed by a microcontroller to perform a predetermined operation. And as can be inferred, in another implementation, the term module may refer to a combination of a microcontroller and a non-transient medium. Typically, the boundaries of the modules illustrated as being separated may vary and potentially overlap. For example, a first module and a second module may share hardware, software, firmware, or a combination thereof while potentially retaining some independent hardware, software, or firmware.

[0153] Embodiments of the mechanisms disclosed herein may be implemented in hardware, software, firmware, or a combination of such implementations. Embodiments of the invention may be implemented as a computer program or program code executed on a programmable system comprising at least one processor, a storage system (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device.

[0154] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A detection circuit for a three-phase AC system, comprising: a leakage current sensor configured to sense a leakage current in the three-phase AC system and generate a leakage current signal; an isolating switch circuit electrically coupled to output ends of a plurality of live relays and neutral relays of the three-phase AC system; A voltage division detection circuit, electrically coupled to the isolation switch circuit, wherein the voltage division detection circuit is configured to divide the DC voltage to output a voltage detection signal; a grounding switch circuit, electrically coupled to the voltage division detection circuit; as well as The control module is configured to control the isolation switch circuit and the grounding switch circuit to detect whether there is a fault in the three-phase AC system based on the leakage current signal or the voltage detection signal.

2. The detection circuit according to claim 1, wherein: The voltage-dividing detection circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor and a fifth voltage-dividing resistor electrically coupled in series, wherein the first voltage-dividing resistor is electrically coupled to the second voltage-dividing resistor at a first node, the second voltage-dividing resistor is electrically coupled to the third voltage-dividing resistor at a second node, the third voltage-dividing resistor is electrically coupled to the fourth voltage-dividing resistor at a third node, and the fourth voltage-dividing resistor is electrically coupled to the fifth voltage-dividing resistor at a fourth node.

3. The detection circuit according to claim 2, wherein: The isolating switch circuit comprises: A first isolation switch configured to receive a signal from an output terminal of a first live relay, the first isolation switch being electrically coupled in series with a first isolation resistor and electrically coupled to the first node in the voltage division detection circuit; a second isolation switch configured to receive a signal from an output terminal of a second live relay, the second isolation switch being electrically coupled in series with a second isolation resistor and electrically coupled to the second node in the voltage division detection circuit; a third isolation switch configured to receive a signal from an output terminal of a third live relay, the third isolation switch being electrically coupled in series with a third isolation resistor and electrically coupled to the third node in the voltage division detection circuit; and The fourth isolation switch is configured to receive a signal from an output terminal of the neutral line relay, and the fourth isolation switch is electrically coupled to the fourth node in the voltage division detection circuit.

4. The detection circuit according to claim 3, wherein: The control module is configured to: The grounding switch circuit is placed in a non-full disconnection mode, and one of the isolating switches in the isolating switch circuit is closed, so as to detect whether there is a fault in the three-phase AC system based on the leakage current signal or the voltage detection signal; as well as The grounding switch circuit is placed in a full disconnection mode, and all the isolation switches in the isolation switch circuit are closed, so as to detect whether there is a fault in the three-phase AC system based on the voltage detection signal.

5. The detection circuit according to claim 4, wherein: The grounding switch circuit comprises: a first grounding switch electrically coupled to the first node in the voltage division detection circuit; a second grounding switch electrically coupled to the second node in the voltage division detection circuit; and a third grounding switch, electrically coupled to the third node in the voltage division detection circuit, Wherein, the control module is configured to obtain the voltage detection signal at the fourth node.

6. The detection circuit according to claim 5, wherein: When at least one of the first grounding switch, the second grounding switch, and the third grounding switch is configured to be closed, the grounding switch circuit is in the non-full-open mode; When the first grounding switch, the second grounding switch, and the third grounding switch are all configured to be opened, the grounding switch circuit is in the all-opening mode.

7. The detection circuit according to claim 6, wherein: The control module is configured to: placing the grounding switch circuit in the non-full disconnection mode, closing a target isolating switch, and opening other isolating switches in the isolating switch circuit, wherein the target isolating switch is one of the first isolating switch, the second isolating switch, or the third isolating switch connected to the same node in the voltage division detection circuit as a closed grounding switch in the grounding switch circuit; and If it is determined that the leakage current signal is an alarm signal, it indicates that there is a fault in the three-phase AC system.

8. The detection circuit according to claim 6, wherein: The control module is configured to: placing the grounding switch circuit in the full disconnection mode and opening all disconnecting switches in the disconnecting switch circuit; and The voltage detection signal is determined as a reference voltage.

9. The detection circuit according to claim 8, wherein: The control module is configured to: placing the grounding switch circuit in the non-full disconnection mode, closing the fourth isolating switch, and opening other isolating switches in the isolating switch circuit; calculating a difference between the voltage detection signal and the reference voltage; as well as If it is determined that the difference is greater than or equal to a predetermined threshold, it indicates that a fault exists in the three-phase AC system.

10. The detection circuit according to claim 8, wherein: The control module is configured to: placing the grounding switch circuit in the full disconnection mode and closing all disconnecting switches in the disconnecting switch circuit; calculating a difference between the voltage detection signal and the reference voltage; as well as If it is determined that the difference is greater than or equal to a predetermined threshold, it indicates that a fault exists in the three-phase AC system.

11. The detection circuit according to claim 4, in, The grounding switch circuit comprises: a ground switch electrically coupled to the first node; Wherein, the voltage division detection circuit further comprises: A first optical coupling module, wherein an input end of the first optical coupling module is electrically coupled to the first node and the second node, and an output end of the first optical coupling module is configured to output a first optical coupling signal; A second optical coupling module, wherein an input end of the second optical coupling module is electrically coupled to the second node and the third node, and an output end of the second optical coupling module is configured to output a second optical coupling signal; a third optical coupling module, wherein an input end of the third optical coupling module is electrically coupled to the third node and the fourth node, and an output end of the third optical coupling module is configured to output a third optical coupling signal; a fourth optical coupling module, wherein the input end of the fourth optical coupling module is electrically coupled to the two ends of the fifth voltage-dividing resistor, and the output end of the fourth optical coupling module is configured to output a fourth optical coupling signal, Wherein, the voltage detection signal includes the first optocoupler signal, the second optocoupler signal, the third optocoupler signal and the fourth optocoupler signal.

12. The detection circuit according to claim 11, wherein: When the grounding switch is configured to be closed, the grounding switch circuit is in the non-full-open mode; When the grounding switch is configured to be open, the grounding switch circuit is in the full open mode.

13. The detection circuit according to claim 12, wherein: The control module is configured to: placing the grounding switch circuit in the full disconnection mode and disconnecting all disconnecting switches in the disconnecting switch circuit; as well as If it is determined that the first optocoupler signal, the second optocoupler signal, the third optocoupler signal and the fourth optocoupler signal are at the first level, it indicates that the detection circuit operates normally.

14. The detection circuit according to claim 12, wherein: The control module is configured to: placing the grounding switch circuit in the non-full disconnection mode, closing the first isolating switch, and opening other isolating switches in the isolating switch circuit; and If it is determined that the leakage current signal is an alarm signal, it indicates that there is a fault in the three-phase AC system.

15. The detection circuit according to claim 12, wherein: The control module is configured to: The grounding switch circuit is placed in the non-full disconnection mode, one of the second isolating switch, the third isolating switch and the fourth isolating switch is closed, and the other isolating switches in the isolating switch circuit are opened; as well as If it is determined that at least one of the first optocoupler signal, the second optocoupler signal, the third optocoupler signal, and the fourth optocoupler signal is at the first level, it indicates that there is a fault in the three-phase AC system.

16. The detection circuit according to claim 12, wherein: The control module is configured to: placing the grounding switch circuit in the full disconnection mode and closing all disconnecting switches in the disconnecting switch circuit; as well as If it is determined that at least one of the first optocoupler signal, the second optocoupler signal, the third optocoupler signal, and the fourth optocoupler signal is at the second level, it indicates that there is a fault in the three-phase AC system.

17. The detection circuit according to claim 3, wherein: The ratio of the voltage divider resistor to the isolation resistor is greater than or equal to 10:

1.

18. A power supply device, comprising: A plurality of live wire relays and neutral wire relays provided on the live wire and the neutral wire of the three-phase AC system; as well as A detection circuit as claimed in any one of claims 1 to 17.

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