A ground detection circuit and control system

Abstract

The present invention relates to the technical field of charging piles, and in particular to a grounding detection circuit and control system, wherein the grounding detection circuit comprises a first voltage divider circuit and a first detection circuit, wherein the first voltage divider circuit comprises a capacitor CY1 and a capacitor C1 connected in series between an L line and a PE line, and the first detection circuit outputs a first detection signal to a controller according to the voltage across the capacitor C1. The present invention provides a grounding detection circuit that can accurately and quickly determine a grounding fault of a charging pile in real time and cut off AC input and DC output in a timely manner, and can meet the insulation withstand voltage and safety requirements of the charging pile, and has high safety and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of charging piles, and in particular to a grounding detection circuit and a control system. Background Art

[0002] With the enhancement of people's environmental awareness and the guidance of government policies, new energy electric vehicles have been widely developed. Charging piles are an important basic support for electric vehicles and one of the key conditions for realizing the industrialization and popularization of electric vehicles. Correspondingly, the safety and reliability of charging piles have also attracted much attention. As charging piles work for a long time, the aging resistance of cable rubber and thermoplastic materials often decreases, and even the insulation layer peels off. If the ground wire of the charging pile is suspended, and the ground fault cannot be detected and the AC input and output cannot be cut off, it will damage the electrical equipment and may also endanger personal safety.

[0003] In the existing technology, some grounding detection schemes have the problem of not meeting safety risk requirements. Some grounding detection schemes use various grounding detection instruments, which have the problems of high cost, inconvenient operation, and single function. Some grounding detection schemes use technologies such as resistor voltage division and optocoupler isolation, which have the problems of not meeting safety voltage resistance requirements and weak anti-interference ability.

[0004] Therefore, in order to solve the problem of imperfect existing charging pile grounding fault detection technology solutions, new grounding detection and control technologies are needed to improve the safety and reliability of charging piles. Summary of the invention

[0005] The present invention aims to solve the technical problem that the safety and reliability of charging pile grounding detection in the prior art are poor, and provides a grounding detection circuit and a control system with high safety, fast detection speed and high reliability.

[0006] The technical solution adopted by the present invention is:

[0007] A ground detection circuit, comprising:

[0008] A first voltage divider circuit, the first voltage divider circuit comprising a capacitor CY1 and a capacitor C1 connected in series between the L line and the PE line;

[0009] A first detection circuit, wherein the first detection circuit outputs a first detection signal to a controller according to the voltage across the capacitor C1.

[0010] Furthermore, the capacitor CY1 is a safety capacitor.

[0011] Furthermore, the first detection circuit includes a transistor Q1, the base of the transistor Q1 is connected to the first end of the capacitor C1, the emitter of the transistor Q1 is connected to the second end of the capacitor C1 and to the PE line and the GND end, the collector of the transistor Q1 is connected to the power supply VCC1 via the pull-up resistor R4, and the collector of the transistor Q1 is connected to the controller to output a first detection signal.

[0012] Furthermore, the first detection circuit further includes a voltage regulator tube ZD1, an anode of the voltage regulator tube ZD1 is connected to the base of the transistor Q1, and a cathode of the voltage regulator tube ZD1 is connected to the first end of the capacitor C1.

[0013] Furthermore, the first detection circuit further includes a diode D1, an anode of the diode D1 is connected to the GND terminal, and a cathode of the diode D1 is connected to the first terminal of the capacitor C1.

[0014] Furthermore, the ground detection circuit also includes a first filtering circuit, which is connected between the first detection circuit and the controller and is used to filter the first detection signal.

[0015] Furthermore, the ground detection circuit further includes a first level conversion circuit, which is connected between the first detection circuit and the controller and is used for performing a level inversion on the filtered first detection signal.

[0016] Furthermore, the first level conversion circuit includes a MOS transistor Q2, a gate of the MOS transistor Q2 is connected to the collector of the transistor Q1, a drain of the MOS transistor Q2 is connected to the power supply VCC2 via a resistor R8, and a source of the MOS transistor Q2 is connected to the GND terminal.

[0017] Furthermore, the ground detection circuit further includes:

[0018] A second voltage divider circuit, the second voltage divider circuit comprising a capacitor CY2 and a capacitor C2 connected in series between the N line and the PE line;

[0019] The second detection circuit outputs a second detection signal to the controller according to the voltage across the capacitor C2.

[0020] Furthermore, the controller is also electrically connected to the AC input relay and the DC output relay, and the controller disconnects the AC input relay and the DC output relay according to the first detection signal and / or the second detection signal.

[0021] Another aspect of the present invention discloses a control system, comprising a ground detection circuit as described in any one of the above, and further comprising:

[0022] A power supply microprocessor, wherein the power supply microprocessor controls the power supply module to shut down according to a shutdown signal output by the controller;

[0023] The host computer reminds the user of the ground fault according to the warning signal sent by the controller.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] (1) The ground detection circuit of the present invention connects a Y capacitor in series between the L line and the PE line for voltage division, which can meet the insulation withstand voltage requirements of the charging pile and the allowable leakage value of the ground line specified in the relevant safety standards, making the ground detection circuit of this embodiment safer and more reliable;

[0026] (2) The present invention adjusts the voltage stabilization value of the voltage regulator ZD1 so that when the input voltage is at different voltage values, the ground detection circuit can detect whether the PE line is reliably grounded. Moreover, since the frequency of the first detection signal is the same as the input voltage frequency, it can be determined whether the input voltage frequency is within the required range according to the waveform of the first detection signal.

[0027] (3) The present invention sets a first ground detection circuit and a second ground detection circuit to detect the L line and the N line at the same time, which effectively avoids the problem of misjudgment or failure of the ground detection circuit caused by reverse connection of the L line and the N line, and has a high fault tolerance rate;

[0028] (4) The controller of the present invention determines whether the grounding is normal by judging whether the detection signal received within a fixed period T has a pulse. Compared with the traditional high and low level signals, the detection speed is fast and the power supply circuit of the charging pile can be disconnected more quickly to ensure the safety of equipment and personnel.

[0029] (5) The control system of the present invention directly controls the shutdown of the AC input relay and the DC output relay of the charging pile, which can quickly cut off the connection between the AC power grid and the electrical equipment, and at the same time quickly shut down the power module of the charging pile, with high safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 is a schematic diagram of a ground detection circuit according to a first embodiment of the present invention;

[0032] Figure 2is a structural diagram of a ground detection circuit according to a first embodiment of the present invention;

[0033] Figure 3 is a structural diagram of a second ground detection circuit according to a second embodiment of the present invention;

[0034] Figure 4 This is a connection diagram of a controller according to Embodiment 2 of the present invention;

[0035] Figure 5 This is a schematic diagram of a control system according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0036] The purpose of the present invention is to solve the technical problem of imperfect grounding fault detection of existing charging piles, and to provide a charging pile real-time grounding detection circuit and control system that can accurately and quickly determine the grounding fault of the charging pile and cut off the AC input and DC output in time. The specific implementation of the present invention is described in detail below with reference to the accompanying drawings.

[0037] Embodiment 1:

[0038] like Figure 1-2 As shown, the ground detection circuit of this embodiment includes a first voltage divider circuit and a first detection circuit. The first voltage divider circuit includes a capacitor CY1 and a capacitor C1 connected in series between the L line and the PE line. The first detection circuit outputs a first detection signal to the controller according to the voltage across the capacitor C1. Specifically, Figure 2 As shown, the first end of capacitor CY1 is connected to the L line, ie, the single-phase electrical connection, the second end of capacitor CY1 is connected to the first end of capacitor C1, and the second end of capacitor C1 is connected to the PE line, ie, the ground line.

[0039] In this way, a capacitor voltage-dividing circuit is formed, capacitor CY1 and capacitor C1 divide the single-phase electricity, the first detection circuit detects the voltage across capacitor C1 and outputs a first detection signal to the controller, and the controller determines whether a grounding fault occurs based on the detected voltage signal, that is, whether the PE line is normally connected to the ground. Specifically, if the PE line is grounded normally, then the two ends of capacitor C1 will be divided to obtain a certain voltage, and the first detection voltage output to the controller by the first filter circuit has a specific waveform, and the controller determines that the PE line is normally grounded based on the voltage waveform; and if the PE line is not normally grounded, such as being in a suspended state, then there is no voltage across capacitor C1, and the first detection voltage output to the controller by the first filter circuit is always 0 or a constant value, and the controller determines that the PE line is not normally grounded.

[0040] The ground detection circuit of this embodiment uses capacitor CY1 and capacitor C1 for voltage division. The withstand voltage of the capacitor is very high. Capacitor CY1 is preferably a safety capacitor, such as a Y capacitor, which has a high withstand voltage of up to several thousand volts, which can meet the insulation withstand voltage requirements of the charging pile and the allowable leakage value of the ground wire specified in the relevant safety standards. This makes the ground detection circuit of this embodiment safer and more reliable. Of course, capacitor C1 can also use a Y capacitor.

[0041] like Figure 2 As shown, the first detection circuit of this embodiment includes a transistor Q1, the base of the transistor Q1 is connected to the first end of the capacitor C1, the emitter of the transistor Q1 is connected to the second end of the capacitor C1 and is also connected to the GND end, the collector of the transistor Q1 is connected to the power supply VCC1 via the pull-up resistor R4, and the collector of the transistor Q1 is connected to the controller to directly or indirectly output a first detection signal. In this way, after the PE line is grounded normally, the L line voltage continuously charges and discharges the capacitor C1, and the transistor Q1 repeatedly turns on-off-on. When the voltage across the capacitor C1 causes the transistor Q1 to turn on, the collector of the transistor Q1 is connected to the GND terminal, and the first detection signal output to the controller is a low level. When the voltage across the capacitor C1 causes the transistor Q1 to turn off, the collector of the transistor Q1 is connected to the power supply VCC1. At this time, the first detection signal output to the controller is a high level. Within a cycle of single-phase electricity, the collector of the transistor Q1 will also output a waveform with a certain duty cycle corresponding to the single-phase electricity; when the PE line is suspended, the collector of the transistor Q1 always outputs a high level; the controller can determine whether the PE line is grounded normally based on the detected first detection signal.

[0042] Furthermore, a resistor R1 is connected between the base and emitter of the transistor Q1, so that when the PE line is not properly grounded, the base of the transistor Q1 is kept at a low level to prevent it from being suspended. Furthermore, a capacitor C5 is connected between the base and emitter of the transistor Q1 for filtering to improve anti-interference capability.

[0043] Preferably, if Figure 2As shown, the first detection circuit of this embodiment also includes a voltage regulator tube ZD1, the anode of the voltage regulator tube ZD1 is connected to the base of the transistor Q1, and the cathode of the voltage regulator tube ZD1 is connected to the first end of the capacitor C1, so that during the charging process of the capacitor C1, the voltage across the capacitor C1 gradually increases, and the voltage regulator tube ZD1 can be clamped so that the base voltage of the transistor Q1 is stabilized at a certain value such as the turn-on voltage, which can protect the transistor Q1. In addition, by adjusting the voltage regulation value of the voltage regulator tube ZD1, the transistor Q1 can be set to be turned on at a certain moment of the input voltage, that is, the single-phase electricity, so that by setting the voltage regulation value of the voltage regulator tube ZD1, when the input voltage is at different voltage values, the grounding detection circuit can detect whether the PE line is reliably grounded, and because the frequency of the first detection signal is the same as the input voltage frequency, it can be judged whether the input voltage frequency is within the required range according to the waveform of the first detection signal.

[0044] Furthermore, the first detection circuit of the present embodiment further includes a diode D1, wherein the anode of the diode D1 is connected to the GND terminal, and the cathode of the diode D1 is connected to the first end of the capacitor C1, so that in the negative half cycle of the input voltage, the capacitor C1 is first discharged and then reversely charged, and the reverse voltage between the base and the emitter of the transistor Q1 gradually increases, and the voltage can be clamped by the diode D1 to protect the transistor Q1.

[0045] Preferably, if Figure 2 As shown, the ground detection circuit of this embodiment also includes a first filtering circuit, which is connected between the first detection circuit and the controller and is used to filter the first detection signal. Specifically, the first detection circuit includes a capacitor C4, a resistor R6 and a capacitor C3. The first ends of the capacitor C4 and the resistor R6 are both connected to the collector of the transistor Q1, the second end of the capacitor C4 is connected to the GND end, the second end of the resistor R6 is connected to the first end of the capacitor C3, and the second end of the capacitor C3 is connected to the GND end, forming a Π-shaped filtering circuit, which can filter the first detection signal output by the first detection circuit, connect the second end of the resistor R6 to the controller, and output the filtered first detection signal to the controller, so that the waveform of the output first detection signal is smoother and the detection result is more accurate.

[0046] Preferably, the ground detection circuit of this embodiment further includes a first level conversion circuit, which is connected between the first detection circuit and the controller, and is used to perform level inversion on the first detection signal filtered by the first filter circuit, and the first detection signal ground signal JD1 after level inversion is output to the controller. Specifically, the first level conversion circuit includes a MOS transistor Q2, the gate of the MOS transistor Q2 is connected to the collector of the transistor Q1 via a resistor R6, the drain of the MOS transistor Q2 is connected to the power supply VCC2 via a resistor R8, and the source of the MOS transistor Q2 is connected to the GND terminal. When the input voltage of the L line is in the positive half cycle, the capacitor C1 is charged to a certain moment to turn on the transistor Q1, and the collector of the transistor Q1 is pulled down to a low level. At this time, the MOS transistor Q2 is turned off, and the ground signal JD1 is at a high level; when the input voltage is in the negative half cycle, the transistor Q1 is always turned off, and the collector of the transistor Q1 is always at a high level. At this time, the MOS transistor Q1 is turned on, and the ground signal JD1 is always at a low level. It can be seen that the high level of the ground signal JD1 appears in the positive half cycle of the input voltage, corresponding to the positive half cycle of the input voltage, and the voltage of the power supply VCC2 is set to 3.3V, so that the ground signal JD1 input to the controller meets the input voltage requirement of the controller.

[0047] Furthermore, the first level conversion circuit also includes a resistor R7 and a capacitor C9. The resistor R7 is connected between the gate and source of the MOS tube Q2 to prevent the gate potential from being suspended. The capacitor C9 is connected between the drain and the GND terminal of the MOS tube Q2 to further filter the ground signal JD1 and improve the anti-interference ability.

[0048] In addition, the controller of this embodiment is also electrically connected to the AC input relay and the DC output relay. When the controller determines that the PE line is not grounded normally based on the received detection signal, it can immediately control the AC input relay and the DC output relay to disconnect, thereby ensuring the safety of electrical equipment and personnel.

[0049] In summary, the grounding detection circuit of this embodiment can accurately and quickly determine the grounding fault of the charging pile in real time and cut off the AC input and DC output in time, and can meet the insulation withstand voltage and safety requirements of the charging pile, with high safety and reliability.

[0050] Embodiment 2:

[0051] The grounding detection circuit of this embodiment includes a first grounding detection circuit and a second grounding detection circuit, wherein the first grounding detection circuit is the grounding detection circuit of the first embodiment, and the circuit structure of the second grounding detection circuit is basically the same as that of the first grounding detection circuit, except that the first grounding detection circuit divides the voltage of the L line and the PE line by a capacitor and outputs a grounding signal JD1, and the second grounding detection circuit divides the voltage of the N line and the PE line by a capacitor and outputs a grounding signal JD2. This embodiment performs grounding detection through two grounding detection circuits, and outputs the grounding signal JD1 and the grounding signal JD2 to the controller respectively. The controller determines whether the PE line is grounded normally according to the waveforms of the detected grounding signal JD1 and the grounding signal JD2, and can also determine whether the L line and the N line are reversely connected.

[0052] Specifically, Figure 3 As shown, the second ground detection circuit includes a second voltage divider circuit and a second detection circuit, the second voltage divider circuit includes a capacitor CY2 and a capacitor C2 connected in series between the N line and the PE line, the capacitor CY2 and / or the capacitor C2 are preferably safety capacitors, and the second detection circuit outputs a second detection signal to the controller according to the voltage across the capacitor C2. Specifically, Figure 3 As shown, the first end of the capacitor CY2 is connected to the N line, the second end of the capacitor CY2 is connected to the first end of the capacitor C2, and the second end of the capacitor C2 is connected to the PE line, ie, the ground line.

[0053] Furthermore, the second detection circuit also includes a transistor Q3, a voltage regulator ZD2, a diode D2, a resistor R2 and a capacitor C10, and the connection methods of these components are the same as those of the first detection circuit. Further, the second ground detection circuit also includes a second filter circuit and a second level conversion circuit, and the connection methods of the two are the same as those of the first ground detection circuit, and finally the second level conversion circuit outputs a ground signal JD2.

[0054] like Figure 4 As shown, the grounding signal JD1 and the grounding signal JD2 are respectively sent to the CAP1 port and the CAP2 port of the controller. When the PE line is normally grounded, in the first grounding detection circuit, the capacitor CY1 and the capacitor C1 are connected in series to the L line and the PE line loop, and the grounding signal JD1 obtained after the capacitor C1 divides the voltage through the first detection circuit, the first filter circuit and the first level flip circuit is a pulse signal with the same frequency as the AC input voltage signal of the L line and a duty cycle of about 50%. In the second grounding detection circuit, since N and PE are basically at the same potential, the grounding signal JD2 is a low level without pulses.

[0055] When the PE line is suspended, capacitors CY1, C1, C2 and CY2 are connected in series to the L line and N line loops, and ground signals JD1 and JD2 are both pulse signals with the same frequency and duty cycle of about 50% as the AC input voltage signal.

[0056] During the wiring process of the charging pile, the wiring personnel sometimes connect the L line and the N line of the charging pile input line in reverse. If the PE line is grounded normally at this time, the grounding signal JD1 output by the first grounding detection circuit is low level and has no pulse. The grounding signal JD2 output by the second grounding detection circuit is a pulse signal with the same frequency as the AC input voltage signal and a duty cycle of about 50%.

[0057] Then, in this embodiment, the controller can determine whether there is a grounding fault and whether the L line and the N line are connected reversely by detecting whether there are pulse signals in the grounding signal JD1 and the grounding signal JD2 within a fixed period T. The specific judgment process is as follows: if the grounding signal JD1 is a pulse signal with the same frequency and a duty cycle of about 50% as the AC input voltage signal, and JD2 is a low level and there is no pulse signal, then it is determined that the PE line is grounded normally and the L line and the N line are not connected reversely; if the grounding signal JD1 and the grounding signal JD2 are both pulse signals with the same frequency and a duty cycle of about 50% as the AC input voltage signal, then it is determined that the PE line is suspended; if the grounding signal JD1 is a low level and there is no pulse signal, and the grounding signal JD2 is a pulse signal with the same frequency and a duty cycle of about 50% as the AC input voltage signal, then it can be determined that the L line and the N line are connected reversely, that is, the L line is connected to N and the N line is connected to L, and it can be determined that the PE line is grounded normally.

[0058] If only the first grounding detection circuit is used, misjudgment may occur when the L line and the N line are connected reversely. However, in this embodiment, the first grounding detection circuit and the second grounding detection circuit are arranged to detect the L line and the N line at the same time, which effectively avoids the problem of misjudgment or failure of the grounding detection circuit caused by the reverse connection of the L line and the N line, and has a high fault tolerance rate.

[0059] Furthermore, the controller is electrically connected to the AC input relay and the DC output relay. If it is determined that there is a ground fault or the L line and the N line are connected in reverse, the controller immediately cuts off the AC input relay and the DC output relay. The controller of this embodiment determines whether the grounding is normal by determining whether there is a pulse in the grounding signal within a fixed period T. Compared with traditional high and low level signals, the detection speed is fast and the power supply circuit of the charging pile can be disconnected more quickly to ensure the safety of equipment and personnel.

[0060] To sum up, the grounding detection circuit provided in this embodiment can effectively determine whether the PE line is grounded normally, and can also determine whether the L line and the N line are reversed. The detection speed is fast, and the power supply circuit of the charging pile can be disconnected more quickly to ensure the safety of equipment and personnel.

[0061] Embodiment three:

[0062] like Figure 5As shown, this embodiment provides a control system. The control system of this embodiment includes the grounding detection circuit of embodiment 2, and also includes a power supply microprocessor and a host computer. The power supply microprocessor controls the power supply module to shut down according to the shutdown signal output by the controller, and the host computer reminds the user of the grounding fault according to the warning signal sent by the controller.

[0063] After the controller determines that there is a ground fault or the L and N lines are connected in reverse, the controller immediately cuts off the AC input relay and the DC output relay, and notifies the power microprocessor through communication to shut down the power module of the charging pile. At the same time, it sends a warning message to the host computer through the wireless network to remind the user that a ground fault or reverse connection of the L and N lines has occurred.

[0064] To sum up, the control system of this embodiment directly controls the shutdown of the AC input relay and the DC output relay of the charging pile, which can quickly cut off the connection between the AC power grid and the electrical equipment, and quickly shut down the power module of the charging pile, with high safety and reliability.

[0065] Any process or method description in a flowchart or otherwise described herein may be understood to represent a circuit, segment or portion of a code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0066] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0068] The above embodiments are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A ground detection circuit, characterized in that: include: A first voltage divider circuit, the first voltage divider circuit comprising a capacitor CY1 and a capacitor C1 connected in series between the L line and the PE line; A first detection circuit, wherein the first detection circuit outputs a first detection signal to a controller according to the voltage across the capacitor C1; The first detection circuit includes a transistor Q1, the base of the transistor Q1 is connected to the first end of the capacitor C1, the emitter of the transistor Q1 is connected to the second end of the capacitor C1 and to the PE line and the GND end, the collector of the transistor Q1 is connected to the power supply VCC1 via the pull-up resistor R4, and the collector of the transistor Q1 is connected to the controller to output a first detection signal; The first detection circuit further includes a voltage regulator tube ZD1, wherein the anode of the voltage regulator tube ZD1 is connected to the base of the transistor Q1, and the cathode of the voltage regulator tube ZD1 is connected to the first end of the capacitor C1; The ground detection circuit further includes a first filtering circuit, which is connected between the first detection circuit and the controller and is used to filter the first detection signal; The ground detection circuit further includes a first level conversion circuit, which is connected between the first detection circuit and the controller and is used for performing a level inversion on the filtered first detection signal.

2. The ground detection circuit according to claim 1, characterized in that: The capacitor CY1 is a safety capacitor.

3. The ground detection circuit according to claim 1, characterized in that: The first detection circuit further includes a diode D1 , wherein an anode of the diode D1 is connected to the GND terminal, and a cathode of the diode D1 is connected to the first terminal of the capacitor C1 .

4. The ground detection circuit according to claim 1, characterized in that: The first level conversion circuit includes a MOS transistor Q2, a gate of the MOS transistor Q2 is connected to the collector of the transistor Q1, a drain of the MOS transistor Q2 is connected to the power supply VCC2 via a resistor R8, and a source of the MOS transistor Q2 is connected to the GND terminal.

5. The ground detection circuit according to claim 1, characterized in that: The ground detection circuit also includes: A second voltage divider circuit, the second voltage divider circuit comprising a capacitor CY2 and a capacitor C2 connected in series between the N line and the PE line; The second detection circuit outputs a second detection signal to the controller according to the voltage across the capacitor C2.

6. The ground detection circuit according to claim 5, characterized in that: The controller is also electrically connected to the AC input relay and the DC output relay, and the controller disconnects the AC input relay and the DC output relay according to the first detection signal and / or the second detection signal.

7. A control system, characterized in that: The ground detection circuit according to any one of claims 1 to 6 further comprises: A power supply microprocessor, wherein the power supply microprocessor controls the power supply module to shut down according to a shutdown signal output by the controller; The host computer reminds the user of the ground fault according to the warning signal sent by the controller.

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