Grounding continuity detection circuit and charging pile

Abstract

The invention discloses a grounding continuity detection circuit and a charging pile, the grounding continuity detection circuit comprises a capacitance voltage division circuit, the input end of the capacitance voltage division circuit is used for connecting a phase line and a zero line, and the output end of the capacitance voltage division circuit is used for outputting a first voltage division signal; the voltage reduction circuit is connected with the capacitance voltage division circuit and used for carrying out voltage reduction processing on the first voltage division signal and outputting a second voltage division signal; the input end of the photoelectric coupler is connected with the protection grounding wire and the step-down circuit, and the output end of the photoelectric coupler is connected with the grounding end and the pull-up circuit and used for conducting or cutting off according to the connection state of the second voltage division signal and the protection grounding wire; and the control circuit is connected with the photoelectric coupler and the pull-up circuit, and is used for acquiring an analog voltage signal corresponding to a connection node between the photoelectric coupler and the pull-up circuit, and detecting the grounding continuity of the protection grounding wire according to the analog voltage signal. According to the technical scheme, the accuracy of grounding continuity detection of the protection grounding wire can be improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a ground continuity detection circuit and a charging pile. Background Art

[0002] With the popularity of electric vehicles, the safety and reliability of charging piles as key infrastructure have become the focus of attention. Ground continuity detection is an important part of ensuring the safe operation of charging piles. Its function is to safely conduct current to the ground when a fault such as leakage occurs in the charging pile, thereby protecting the safety of personnel and equipment.

[0003] However, existing charging pile grounding continuity detection technology has significant defects. In terms of dielectric testing, most detection circuits are not stable enough under high-voltage environments, making it difficult to accurately reflect the grounding status, resulting in inaccurate dielectric test results and even possible safety accidents. For example, some circuit components are vulnerable to high-voltage shocks and cannot provide a reliable grounding path. In terms of insulation impedance detection, traditional methods have low accuracy and cannot detect small changes in insulation impedance in a timely manner, making it difficult to meet the high requirements of modern charging piles for safety and reliability. Summary of the invention

[0004] The embodiments of the present invention provide a ground continuity detection circuit and a charging pile to solve the problem of low reliability of the existing ground continuity detection.

[0005] A ground continuity detection circuit is used in a charging pile, comprising a capacitor voltage divider circuit, a voltage step-down circuit, a photocoupler, a pull-up circuit and a control circuit; The input end of the capacitor voltage divider circuit is used to connect the phase line and the neutral line, and the output end of the capacitor voltage divider circuit is used to output a first voltage division signal; The step-down circuit is connected to the capacitive voltage-dividing circuit, and is used to step down the first voltage-dividing signal and output a second voltage-dividing signal; The photoelectric coupler input end is connected to the protective ground line and the step-down circuit, and the photoelectric coupler output end is connected to the ground end and the pull-up circuit, and is used to be turned on or off according to the connection state of the second voltage-divided signal and the protective ground line; The control circuit is connected to the photoelectric coupler and the pull-up circuit, and is used to collect an analog voltage signal corresponding to a connection node between the photoelectric coupler and the pull-up circuit, and detect the grounding continuity of the protective grounding wire according to the analog voltage signal.

[0006] Further, the voltage divider circuit includes a first capacitor circuit and a second capacitor circuit; The first end of the first capacitor circuit is used to connect the phase line or the neutral line, and the second end of the first capacitor circuit is connected to the first end of the step-down circuit; The second end of the second capacitor circuit is used to connect the neutral line or the phase line, and the second end of the second capacitor circuit is connected to the first end of the step-down circuit; The capacitance value presented by the first capacitance circuit is the same as the capacitance value presented by the second capacitance circuit.

[0007] Further, the step-down circuit includes a resistance circuit; The resistance circuit includes a plurality of resistors, and the plurality of resistors are connected in series and / or in parallel.

[0008] Further, the photoelectric coupler includes a photodiode and a phototransistor; The anode of the photodiode is connected to the step-down circuit, and the cathode of the photodiode is connected to the protective grounding wire; The collector of the phototransistor is connected to the pull-up circuit and the control circuit, and the emitter of the phototransistor is connected to the ground terminal.

[0009] Further, the control circuit includes an analog-to-digital conversion circuit and a signal processing circuit; The analog-to-digital conversion circuit is connected to the photoelectric coupler and the pull-up circuit, and is used to perform analog-to-digital conversion processing on the analog voltage signal and output a digital voltage signal; The signal processing circuit is connected to the analog-to-digital conversion circuit, and is used to determine that the grounding continuity of the protective grounding wire is abnormal if the peak voltage corresponding to the digital voltage signal is greater than or equal to a first voltage threshold; if the peak voltage corresponding to the digital voltage signal is less than or equal to a second voltage threshold, then determine that the grounding continuity of the protective grounding wire is normal; and the second voltage threshold is less than the first voltage threshold.

[0010] Further, the ground continuity detection circuit includes a surge suppression circuit; The first end of the surge suppression circuit is connected to the input end of the photoelectric coupler, and the second end of the surge suppression circuit is connected to the protective grounding line, and is used to suppress the surge signal at the input end of the photoelectric coupler.

[0011] Furthermore, the surge suppression circuit includes a first capacitor and a first diode which are arranged in parallel.

[0012] Furthermore, the ground continuity detection circuit includes a filter circuit, a first end of the filter circuit is connected to the output end of the photoelectric coupler, and a second end of the filter circuit is connected to the ground end, for filtering out high-frequency signals output from the output end of the photoelectric coupler.

[0013] Furthermore, the filter capacitor includes a second capacitor.

[0014] A charging pile comprises the above-mentioned ground continuity detection circuit.

[0015] The embodiment of the present invention provides a ground continuity detection circuit and a charging pile, wherein the ground continuity detection circuit includes a capacitor voltage divider circuit, a voltage step-down circuit, a photoelectric coupler, a pull-up circuit and a control circuit; the input end of the capacitor voltage divider circuit is used to connect the phase line and the neutral line, and the output end of the capacitor voltage divider circuit is used to output a first voltage division signal; the voltage step-down circuit is connected to the capacitor voltage divider circuit, and is used to step down the first voltage division signal and output a second voltage division signal; the input end of the photoelectric coupler is connected to the protective ground line and the voltage step-down circuit, and the output end of the photoelectric coupler is connected to the ground end and the pull-up circuit, and is used to turn on or off according to the connection state of the second voltage division signal and the protective ground line The control circuit is connected to the photoelectric coupler and the pull-up circuit, and is used to collect the analog voltage signal corresponding to the connection node between the photoelectric coupler and the pull-up circuit, and detect the grounding continuity of the protective grounding wire according to the analog voltage signal, so as to detect the grounding continuity of the protective grounding wire in real time through the photoelectric coupler, and utilize the voltage reduction processing of the voltage reduction circuit and the isolation performance of the photoelectric coupler to improve the dielectric test withstand voltage capability and insulation impedance performance at the same time, and the control circuit detects the grounding continuity of the protective grounding wire through the analog voltage signal, and more reliably identifies whether the photoelectric coupler is turned on or off, thereby improving the accuracy of the grounding continuity detection of the protective grounding wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description 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 labor.

[0017] Figure 1 is a schematic diagram of a ground continuity detection circuit in one embodiment of the present invention; Figure 2 is a schematic diagram of an analog voltage signal according to an embodiment of the present invention.

[0018] In the figure: 1. capacitor voltage divider circuit; 11. first capacitor circuit; 12. second capacitor circuit; 2. step-down circuit; 3. photocoupler; 4. pull-up circuit; 5. control circuit; 6. surge suppression circuit; 7. filter circuit. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0021] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0022] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0023] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "a", "an" and " / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "consisting of" and / or "comprising" when used in this specification determine the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0024] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0025] This embodiment provides a ground continuity detection circuit, which is applied in a charging pile, such as Figure 1 As shown, it includes a capacitor voltage divider circuit 1, a step-down circuit 2, a photoelectric coupler 3, a pull-up circuit 4 and a control circuit 5; the input end of the capacitor voltage divider circuit 1 is used to connect the phase line L_in and the neutral line N_in, and the output end of the capacitor voltage divider circuit 1 is used to output a first divided voltage signal; the step-down circuit 2 is connected to the capacitor voltage divider circuit 1, and is used to step down the first divided voltage signal and output a second divided voltage signal; the input end of the photoelectric coupler 3 is connected to the protective grounding line PE and the step-down circuit 2, and the output end of the photoelectric coupler 3 is connected to the ground end and the pull-up circuit 4, and is used to turn on or off according to the connection state of the second divided voltage signal and the protective grounding line PE; the control circuit 5 is connected to the photoelectric coupler 3 and the pull-up circuit 4, and is used to collect the analog voltage signal corresponding to the connection node between the photoelectric coupler 3 and the pull-up circuit 4, and detect the grounding continuity of the protective grounding line PE according to the analog voltage signal.

[0026] The ground continuity detection circuit is used in a charging pile. The phase line L_in is a single-phase line L_in. The voltage range between the phase line L_in and the neutral line N_in is 85V-300V, which is adapted to the global power grid standard.

[0027] As an example, when the charging pile is normally charged and discharged, the capacitor voltage divider circuit 1 divides the voltage between the phase line L_in and the neutral line N_in, and outputs a first voltage divider signal. The step-down circuit 2 steps down the first voltage divider signal and outputs a second voltage divider signal to the photoelectric coupler 3 to ensure that the photoelectric coupler 3 can work normally. When the connection state of the protective grounding wire PE at the input end of the photoelectric coupler 3 is normal, the photoelectric coupler 3 is turned on, and when the connection state of the protective grounding wire PE at the input end of the photoelectric coupler 3 is abnormal, the photoelectric coupler 3 is cut off. Since the output end of the photoelectric coupler 3 is connected to the ground end and the pull-up circuit 4, the photoelectric coupler 3 generates different analog voltage signals at the connection node between the photoelectric coupler 3 and the pull-up circuit 4 in the on and off states, so that the control circuit 5 detects the grounding continuity of the protective grounding wire PE according to the analog voltage signal.

[0028] In this embodiment, the ground continuity detection circuit includes a capacitor voltage divider circuit 1, a step-down circuit 2, a photoelectric coupler 3, a pull-up circuit 4 and a control circuit 5; the input end of the capacitor voltage divider circuit 1 is used to connect the phase line L_in and the neutral line N_in, and the output end of the capacitor voltage divider circuit 1 is used to output a first divided voltage signal; the step-down circuit 2 is connected to the capacitor voltage divider circuit 1, and is used to step down the first divided voltage signal and output a second divided voltage signal; the input end of the photoelectric coupler 3 is connected to the protective ground line PE and the step-down circuit 2, and the output end of the photoelectric coupler 3 is connected to the ground end and the pull-up circuit 4, and is used to turn on or off according to the connection state of the second divided voltage signal and the protective ground line PE; the control circuit The circuit 5 is connected to the photoelectric coupler 3 and the pull-up circuit 4, and is used to collect the analog voltage signal corresponding to the connection node between the photoelectric coupler 3 and the pull-up circuit 4, and detect the grounding continuity of the protective grounding wire PE according to the analog voltage signal, so as to detect the grounding continuity of the protective grounding wire PE in real time through the photoelectric coupler 3, and utilize the voltage reduction processing of the voltage reduction circuit 2 and the isolation performance of the photoelectric coupler 3 to improve the dielectric test withstand voltage capability and insulation impedance performance at the same time, and the control circuit 5 detects the grounding continuity of the protective grounding wire PE through the analog voltage signal, and more reliably identifies whether the photoelectric coupler 3 is turned on or off, thereby improving the accuracy of the grounding continuity detection of the protective grounding wire PE.

[0029] In one embodiment, the voltage divider circuit includes a first capacitor circuit 11 and a second capacitor circuit 12; the first end of the first capacitor circuit 11 is used to connect the phase line L_in or the neutral line N_in, and the second end of the first capacitor circuit 11 is connected to the first end of the step-down circuit 2; the second end of the second capacitor circuit 12 is used to connect the neutral line N_in or the phase line L_in, and the second end of the second capacitor circuit 12 is connected to the first end of the step-down circuit 2; the capacitance value presented by the first capacitor circuit 11 is the same as the capacitance value presented by the second capacitor circuit 12.

[0030] As an example, the first capacitor circuit 11 and the second capacitor circuit 12 may include a single capacitor or multiple capacitors respectively, as long as the capacitance value presented by the first capacitor circuit 11 and the capacitance value presented by the second capacitor circuit 12 are the same.

[0031] As an example, the first capacitor circuit 11 includes capacitors CY1 and CY2 connected in series, and the second capacitor circuit 12 includes capacitors CY3 and CY4 connected in series. Capacitors CY1-CY4 are arranged in series between the phase line L_in and the neutral line N_in. The rated voltage of each capacitor is ≥2kV, and the total withstand voltage of capacitors CY1-CY4 after being connected in series is ≥8kV, and the capacitance of each capacitor is 2.2nF, and the equivalent capacitance after being connected in series is 1.1nF, which is used to balance the voltage division and suppress common mode interference.

[0032] In this embodiment, the voltage divider circuit includes a first capacitor circuit 11 and a second capacitor circuit 12; the first end of the first capacitor circuit 11 is used to connect the phase line L_in or the neutral line N_in, and the second end of the first capacitor circuit 11 is connected to the first end of the step-down circuit 2; the second end of the second capacitor circuit 12 is used to connect the neutral line N_in or the phase line L_in, and the second end of the second capacitor circuit 12 is connected to the first end of the step-down circuit 2; the capacitance value presented by the first capacitor circuit 11 is the same as the capacitance value presented by the second capacitor circuit 12, so that no matter whether the phase line L_in and the neutral line N_in are connected positively or reversely, it can ensure that the second voltage-divided signal received by the input end of the optical coupler can make the optical coupler work normally, solving the problem of misjudgment and high-voltage breakdown caused by the reverse connection of the live wire and the neutral line N_in in the traditional ground continuity detection circuit. At the same time, the circuit for separately detecting the phase line L_in and the neutral line N_in is omitted, reducing costs.

[0033] In one embodiment, the step-down circuit 2 includes a resistance circuit; the resistance circuit includes a plurality of resistors, and the plurality of resistors are connected in series and / or in parallel.

[0034] In this embodiment, the voltage reduction process is performed through a resistor circuit, which has a simple structure and low cost.

[0035] As an example, the resistor circuit includes resistors R2, R3, R4 and R5 connected in series, the withstand voltage of a single resistor is ≥1kV, the total withstand voltage of the resistor circuit is ≥4kV, and the total resistance of the resistor circuit is 1.2MΩ, so that the leakage current is ≤0.1mA under 220V AC. Among them, the resistance value of a single resistor is 300kΩ, the rated power is 0.5W, and the resistance change rate of a single resistor is <2% under 85℃ environment to avoid resistance drift and insulation degradation caused by high temperature.

[0036] In this embodiment, the total withstand voltage of the voltage divider circuit in the above embodiment is 8kV (4×2kV), and the total withstand voltage of the resistance circuit is 4kV (4×1kV), so that the ground continuity detection circuit can withstand a 5kV / 60s dielectric test; wherein, under 220V AC, the leakage current of the resistance circuit is only 0.18mA, and after superimposing the capacitive reactance of the voltage divider circuit (1.1nF corresponds to 50Hz capacitive reactance≈2.89MΩ), the total leakage current of the ground continuity detection circuit is <0.1mA, which meets the national / European standard charging equipment safety standards.

[0037] In one embodiment, the photocoupler 3 includes a photodiode and a phototransistor; the anode of the photodiode is connected to the step-down circuit 2, and the cathode of the photodiode is connected to the protective ground line PE; the collector of the phototransistor is connected to the pull-up circuit 4 and the control circuit 5, and the emitter of the phototransistor is connected to the ground terminal.

[0038] As an example, the operating current of the photodiode is designed to be 0.05-0.15 mA, which is adapted to the micro-current characteristics of the high resistance network, that is, the resistance circuit.

[0039] As an example, Figure 2 As shown, the phase line L_in and the neutral line N_in are normally connected: the voltage of the phase line L_in is 220V, the voltage of the neutral line N_in is ≈0V, and after the voltage divider circuit divides the voltage and the resistor circuit steps down the voltage, the voltage at the input end of the photoelectric coupler 3 is ≈1.8V, the photodiode is turned on, and the analog voltage signal is a low level (240mV<0.3V); The phase line L_in and the neutral line N_in are reversely connected: the neutral line N_in is charged with 220V, and the phase line L_in is ≈0V. Due to the anti-reverse connection effect of the voltage divider circuit, that is, the capacitance value presented by the first capacitor circuit 11 of the voltage divider circuit is the same as the capacitance value presented by the second capacitor circuit 12, the voltage at the input end of the photoelectric coupler 3 is still ≈1.8V, and the detection logic remains unchanged.

[0040] When the protective ground wire PE is disconnected, the input current of the photocoupler 3 is zero, the output end of the photocoupler 3 is pulled up to 3.3V by the pull-up circuit 4, the analog voltage signal is high level, and the control circuit 5 triggers an alarm and cuts off the power supply. The pull-up circuit 4 includes a pull-up resistor R1, and the pull-up resistor R1 is connected to the power supply terminal D3.3V.

[0041] When the phase line L_in and the neutral line N_in are connected reversely, the detection accuracy is maintained by a voltage divider circuit.

[0042] In this embodiment, the photocoupler 3 includes a photodiode and a phototransistor; the anode of the photodiode is connected to the step-down circuit 2, and the cathode of the photodiode is connected to the protective ground line PE; the collector of the phototransistor is connected to the pull-up circuit 4 and the control circuit 5, and the emitter of the phototransistor is connected to the ground terminal, thereby achieving electrical isolation while maintaining detection accuracy.

[0043] In one embodiment, the control circuit 5 includes an analog-to-digital conversion circuit and a signal processing circuit; the analog-to-digital conversion circuit is connected to the photocoupler 3 and the pull-up circuit 4, and is used to perform analog-to-digital conversion processing on the analog voltage signal and output a digital voltage signal; the signal processing circuit is connected to the analog-to-digital conversion circuit, and is used to determine that the grounding continuity of the protective ground line PE is abnormal if the peak voltage corresponding to the digital voltage signal is greater than or equal to the first voltage threshold; if the peak voltage corresponding to the digital voltage signal is less than or equal to the second voltage threshold, it is determined that the grounding continuity of the protective ground line PE is normal; the second voltage threshold is less than the first voltage threshold.

[0044] As an example, the analog-to-digital conversion circuit is connected to the photocoupler 3 and the pull-up circuit 4, and is used to perform analog-to-digital conversion processing on the analog voltage signal and output a digital voltage signal. The analog-to-digital conversion circuit performs multi-point sampling on the analog voltage signal according to a preset sampling frequency, converts the continuous analog signal into discrete sampling points, and quantizes the sampled analog signal into a digital value, i.e., a digital voltage signal.

[0045] As an example, if the peak voltage corresponding to the digital voltage signal is greater than or equal to the first voltage threshold, the grounding continuity of the protective ground line PE is judged to be abnormal; if the peak voltage corresponding to the digital voltage signal is less than or equal to the second voltage threshold, the grounding continuity of the protective ground line PE is judged to be normal; the second voltage threshold is less than the first voltage threshold. Exemplarily, the first voltage threshold is 3.3V, and the second voltage threshold is 240mV. If the peak voltage corresponding to the digital voltage signal is greater than or equal to the first voltage threshold, and the holding time is greater than the first preset time, the analog voltage signal is judged to be a high-level signal, and the grounding continuity of the protective ground line PE is judged to be abnormal. If the peak voltage corresponding to the digital voltage signal is less than or equal to the second voltage threshold, the analog voltage signal is judged to be a low-level signal, and the grounding continuity of the protective ground line PE is judged to be normal. Figure 1 As shown, the control circuit 5 includes an MCU, and the MCU includes an analog-to-digital conversion circuit and a signal processing circuit. ADC1 is a signal acquisition port of the analog-to-digital conversion circuit.

[0046] Furthermore, if the peak voltage corresponding to the digital voltage signal is greater than or equal to the first voltage threshold and the holding time is greater than the first preset time, the analog voltage signal is judged to be a high-level signal, and the grounding continuity of the protective ground line PE is judged to be abnormal, thereby preventing misjudgment.

[0047] In this embodiment, the control circuit 5 includes an analog-to-digital conversion circuit and a signal processing circuit; the analog-to-digital conversion circuit is connected to the photocoupler 3 and the pull-up circuit 4, and is used to perform analog-to-digital conversion processing on the analog voltage signal and output a digital voltage signal; the signal processing circuit is connected to the analog-to-digital conversion circuit, and is used to determine that the grounding continuity of the protective grounding wire PE is abnormal if the peak voltage corresponding to the digital voltage signal is greater than or equal to the first voltage threshold; if the peak voltage corresponding to the digital voltage signal is less than or equal to the second voltage threshold, it is determined that the grounding continuity of the protective grounding wire PE is normal; the second voltage threshold is less than the first voltage threshold, so that the analog voltage signal is detected through the analog voltage signal to prevent the analog voltage signal from fluctuating with the phase line voltage, and the high and low levels are more reliably identified, avoiding misjudgment caused by differences in TTL level recognition ranges of MCUs of different brands.

[0048] In one embodiment, the ground continuity detection circuit includes a surge suppression circuit 6; a first end of the surge suppression circuit 6 is connected to the input end of the photocoupler 3, and a second end of the surge suppression circuit 6 is connected to the protective ground line PE, for suppressing the surge signal at the input end of the photocoupler 3.

[0049] In this embodiment, a first end of the surge suppression circuit 6 is connected to the input end of the photocoupler 3 , and a second end of the surge suppression circuit 6 is connected to the protective ground line PE, for suppressing the surge signal at the input end of the photocoupler 3 to ensure the safety of the photocoupler 3 .

[0050] In one embodiment, the surge suppression circuit 6 includes a first capacitor C1 and a first diode D1 arranged in parallel. As an example, the first end of the first capacitor C1 is connected to the anode of the photodiode, and the second end of the first capacitor C1 is connected to the protective ground line PE. The cathode of the second diode is connected to the anode of the photodiode, and the anode of the second diode is connected to the protective ground line PE.

[0051] In this embodiment, the surge suppression circuit 6 includes a first capacitor C1 and a first diode D1 which are connected in parallel, and has a simple structure and low cost.

[0052] In one embodiment, the ground continuity detection circuit includes a filter circuit 7, a first end of the filter circuit 7 is connected to the output end of the photocoupler 3, and a second end of the filter circuit 7 is connected to the ground end, and is used to filter out the high-frequency signal output from the output end of the photocoupler 3. In this embodiment, the first end of the filter circuit 7 is connected to the output end of the photocoupler 3, and the second end of the filter circuit 7 is connected to the ground end, and is used to filter out the high-frequency signal output from the output end of the photocoupler 3 to ensure accurate information of the analog voltage signal.

[0053] In one embodiment, the filter capacitor includes a second capacitor C2. In this embodiment, the filter capacitor includes a second capacitor C2, which has a simple structure and low cost.

[0054] This embodiment provides a charging pile, including the above-mentioned ground continuity detection circuit.

[0055] As an example, the charging pile also includes an input-output relay, and the control circuit 5 is connected to the input-output relay. When the grounding continuity of the protective grounding wire PE is abnormal, the control circuit 5 controls the grounding continuity of the protective grounding wire PE to be disconnected, cuts off the output of the charging pile, and avoids continuous accumulation of leakage current.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A ground continuity detection circuit, characterized in that: Applied in charging piles, including capacitor voltage divider circuit, step-down circuit, photocoupler, pull-up circuit and control circuit; The input end of the capacitor voltage divider circuit is used to connect the phase line and the neutral line, and the output end of the capacitor voltage divider circuit is used to output a first voltage division signal; The step-down circuit is connected to the capacitive voltage-dividing circuit, and is used to step down the first voltage-dividing signal and output a second voltage-dividing signal; The photoelectric coupler input end is connected to the protective ground line and the step-down circuit, and the photoelectric coupler output end is connected to the ground end and the pull-up circuit, and is used to be turned on or off according to the connection state of the second voltage-divided signal and the protective ground line; The control circuit is connected to the photoelectric coupler and the pull-up circuit, and is used to collect an analog voltage signal corresponding to a connection node between the photoelectric coupler and the pull-up circuit, and detect the grounding continuity of the protective grounding wire according to the analog voltage signal.

2. The ground continuity detection circuit according to claim 1, characterized in that: The voltage dividing circuit includes a first capacitor circuit and a second capacitor circuit; The first end of the first capacitor circuit is used to connect the phase line or the neutral line, and the second end of the first capacitor circuit is connected to the first end of the step-down circuit; The second end of the second capacitor circuit is used to connect the neutral line or the phase line, and the second end of the second capacitor circuit is connected to the first end of the step-down circuit; The capacitance value presented by the first capacitance circuit is the same as the capacitance value presented by the second capacitance circuit.

3. The ground continuity detection circuit according to claim 1, characterized in that: The step-down circuit includes a resistance circuit; The resistance circuit includes a plurality of resistors, and the plurality of resistors are connected in series and / or in parallel.

4. The ground continuity detection circuit according to claim 1, characterized in that: The photoelectric coupler includes a photodiode and a phototransistor; The anode of the photodiode is connected to the step-down circuit, and the cathode of the photodiode is connected to the protective grounding wire; The collector of the phototransistor is connected to the pull-up circuit and the control circuit, and the emitter of the phototransistor is connected to the ground terminal.

5. The ground continuity detection circuit according to claim 1, characterized in that: The control circuit includes an analog-to-digital conversion circuit and a signal processing circuit; The analog-to-digital conversion circuit is connected to the photoelectric coupler and the pull-up circuit, and is used to perform analog-to-digital conversion processing on the analog voltage signal and output a digital voltage signal; The signal processing circuit is connected to the analog-to-digital conversion circuit, and is used to determine that the grounding continuity of the protective grounding wire is abnormal if the peak voltage corresponding to the digital voltage signal is greater than or equal to a first voltage threshold; If the peak voltage corresponding to the digital voltage signal is less than or equal to the second voltage threshold, it is determined that the grounding continuity of the protective grounding wire is normal; The second voltage threshold is lower than the first voltage threshold.

6. The ground continuity detection circuit according to claim 1, characterized in that: The ground continuity detection circuit includes a surge suppression circuit; The first end of the surge suppression circuit is connected to the input end of the photoelectric coupler, and the second end of the surge suppression circuit is connected to the protective grounding line, and is used to suppress the surge signal at the input end of the photoelectric coupler.

7. The ground continuity detection circuit according to claim 6, characterized in that: The surge suppression circuit includes a first capacitor and a first diode which are arranged in parallel.

8. The ground continuity detection circuit according to claim 1, characterized in that: The ground continuity detection circuit comprises a filter circuit, a first end of the filter circuit is connected to the output end of the photoelectric coupler, and a second end of the filter circuit is connected to the ground end, for filtering out high-frequency signals output from the output end of the photoelectric coupler.

9. The ground continuity detection circuit according to claim 8, characterized in that: The filter capacitor includes a second capacitor.

10. A charging pile, characterized in that: Comprising a ground continuity detection circuit as claimed in any one of claims 1 to 9.

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