Leakage current detection circuit for alternating current charging pile and alternating current charging pile
By designing a leakage current detection circuit for AC charging piles, using zero-sequence current transformer and amplifier circuit to detect leakage current, the problem of untimely leakage current detection in AC charging piles is solved, and safe and reliable leakage current detection is achieved.
Patent Information
- Application Number
- CN202420692719.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-07
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2034-04-07
AI Technical Summary
How to detect leakage current in AC charging piles in a timely manner to ensure the safety of cars and personnel.
A leakage current detection circuit for AC charging piles is designed, including a zero-sequence current transformer, a conversion circuit, an operational amplifier circuit, a precision rectifier circuit and a MCU. The circuit samples the leakage current signal through a zero-sequence current transformer, converts it into an AC voltage signal, and amplifies the signal through an amplification circuit, and finally detects it at the AD detection end of the MCU.
The actual leakage current value can be quickly detected when the leakage current is small, ensuring that the charging pile stops charging in a timely manner in the event of leakage and ensuring safety.
Smart Images
Figure CN222580230U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of charging piles, and in particular to a leakage current detection circuit for an AC charging pile and an AC charging pile. Background Art
[0002] As a facility that provides AC power supply for new energy vehicles, electric vehicle AC charging piles need to have necessary safety guarantees while meeting the charging function, among which protection against AC leakage is indispensable. Once the charging pile leaks, the charging pile should be able to stop charging immediately and disconnect the AC power supply to ensure the safety of the car and personnel.
[0003] Therefore, how to enable AC charging piles to detect leakage current in time is an important issue that needs to be solved. Utility Model Content
[0004] In order to solve the above problems, the utility model proposes a leakage current detection circuit for an AC charging pile and an AC charging pile, which can detect the leakage current in time.
[0005] In a first aspect, an embodiment of the utility model provides a leakage current detection circuit for an AC charging pile, comprising:
[0006] A zero-sequence current transformer, wherein a first input end of the zero-sequence current transformer is electrically connected to the live wire of the AC charging pile, and a second input end of the zero-sequence current transformer is electrically connected to the neutral wire of the AC charging pile;
[0007] The conversion circuit comprises a one-hundred-ninth resistor R109, wherein a first end of the one-hundred-ninth resistor R109 is electrically connected to a first output end of the zero-sequence current transformer, and a second end of the one-hundred-ninth resistor R109 is electrically connected to a second output end of the zero-sequence current transformer;
[0008] An operation amplifier circuit, the operation amplifier circuit comprising a first operation amplifier U4-A, a first input end of the first operation amplifier U4-A is electrically connected to a first output end of the zero-sequence current transformer, and a second input end of the first operation amplifier U4-A is electrically connected to a second output end of the zero-sequence current transformer;
[0009] A precision rectifier circuit, wherein an input end of the precision rectifier circuit is electrically connected to an output end of the first operational amplifier U4-A;
[0010] MCU, the AD detection end of the MCU is electrically connected to the output end of the precision rectifier circuit.
[0011] The technical solution of the first aspect of the utility model has at least one of the following advantages or beneficial effects:
[0012] The zero-sequence current transformer is mounted on the L / N line of the output power supply line of the AC charging pile to sample the leakage current. The sampled current signal is converted into an AC voltage signal through the 109th resistor R109 of the conversion circuit, and then amplified by dozens of times through the first operating amplifier U4-A. The signal is given to the AD detection end of the MCU. When the leakage current is small, the actual leakage current value can be quickly detected to ensure the safety of the car and personnel.
[0013] Optionally, the precision rectification circuit comprises:
[0014] A second operational amplifier U5-A, wherein a first input terminal of the second operational amplifier U5-A is electrically connected to an output terminal of the first operational amplifier U4-A, a second input terminal of the second operational amplifier U5-A is grounded, and an output terminal of the second operational amplifier U5-A is electrically connected to an AD detection terminal of the MCU;
[0015] A third operational amplifier U5-B, wherein the first input terminal of the third operational amplifier U5-B is electrically connected to the output terminal of the first operational amplifier U4-A, and the second input terminal and output terminal of the third operational amplifier U5-B are electrically connected to the AD detection terminal of the MCU.
[0016] Optionally, the precision rectifier circuit further includes a one hundred and seventh resistor R107, a one hundred and fourth resistor R104, a one hundred and third resistor R103, a ninety-eighth resistor R98, a sixteenth diode D16 and a seventeenth diode D17;
[0017] The first end of the first one hundred and seventh resistor R107 is electrically connected to the output end of the first operational amplifier U4-A, and the second end of the first one hundred and seventh resistor R107 is electrically connected to the first end of the first one hundred and fourth resistor R104;
[0018] The first input terminal of the second operational amplifier U5-A is electrically connected to the second terminal of the first-hundred-and-fourth resistor R104, the first terminal of the first-hundred-and-threeth resistor R103, and the first terminal of the ninety-eighth resistor R98;
[0019] The output terminal of the second operational amplifier U5-A is electrically connected to the cathode of the sixteenth diode D16 and the anode of the seventeenth diode D17;
[0020] An anode of the sixteenth diode D16 is electrically connected to a second end of the ninety-eighth resistor R98;
[0021] The cathode of the seventeenth diode D17 and the second end of the first one hundred and third resistor R103 are electrically connected to the AD detection end of the MCU.
[0022] Optionally, the precision rectifier circuit further includes a one hundred and sixth resistor R106, a one hundred and fifth resistor R105, a fourteenth diode D14 and a fifteenth diode D15;
[0023] The first input terminal of the third operational amplifier U5-B is electrically connected to the second terminal of the first one hundred and seventh resistor R107;
[0024] The second input terminal of the third operational amplifier U5-B is electrically connected to the first end of the first one hundred and sixth resistor R106 and the first end of the first one hundred and fifth resistor R105, the second end of the first one hundred and sixth resistor R106 is electrically connected to the anode of the fifteenth diode D15, and the second end of the first one hundred and fifth resistor R105 is electrically connected to the AD detection terminal of the MCU;
[0025] The output end of the third operational amplifier U5-B is electrically connected to the cathode of the fifteenth diode D15 and the anode of the fourteenth diode D14, and the cathode of the fourteenth diode D14 is electrically connected to the AD detection end of the MCU.
[0026] Optionally, the precision rectifier circuit also includes a ninety-ninth resistor R99, a first end of the ninety-ninth resistor R99 is electrically connected to the second input end of the second operational amplifier U5-A, and a second end of the ninety-ninth resistor R99 is electrically connected.
[0027] Optionally, the operation amplifier circuit further includes a 101st resistor R101, a 102nd resistor R102, a 108th resistor R108 and a 114th resistor R114;
[0028] The first end of the first one hundred and first resistor R101 is electrically connected to the second output end of the zero-sequence current transformer, and the second end of the first one hundred and first resistor R101 is electrically connected to the second input end of the first operational amplifier U4-A;
[0029] The first end of the first one hundred and second resistor R102 is electrically connected to the second end of the first one hundred and first resistor R101, and the second end of the first one hundred and second resistor R102 is grounded;
[0030] The first end of the 114th resistor R114 is electrically connected to the first output end of the zero-sequence current transformer, and the second end of the 114th resistor R114 is electrically connected to the first input end of the first operational amplifier U4-A;
[0031] The first end of the first-hundred-eighth resistor R108 is electrically connected to the second end of the first-hundred-fourteenth resistor R114, and the second end of the first-hundred-eighth resistor R108 is electrically connected to the output end of the first operational amplifier U4-A.
[0032] Optionally, the operation amplification circuit further includes a fifty-fifth capacitor C55 and a sixty-second capacitor C62;
[0033] A first end of the fifty-fifth capacitor C55 is electrically connected to a first end of the first-hundred-and-first resistor R101, a first end of the sixty-second capacitor C62 is electrically connected to a first end of the first-hundred-and-fourteenth resistor R114, and a second end of the fifty-fifth capacitor C55 and a second end of the sixty-second capacitor C62 are grounded.
[0034] Optionally, the operation amplifier circuit further includes a sixtieth capacitor C60 and a sixty-first capacitor C61;
[0035] A first end of the sixtieth capacitor C60 is electrically connected to the first input end of the first operational amplifier U4-A, and a second end of the sixtieth capacitor C60 is grounded;
[0036] The first end of the sixty-first capacitor C61 is electrically connected to the first input end of the first operational amplifier U4-A, and the second end of the sixty-first capacitor C61 is electrically connected to the output end of the first operational amplifier U4-A.
[0037] Optionally, the leakage current detection circuit for the AC charging pile further includes a filter circuit, and the filter circuit includes a 100th resistor R100 and a 59th capacitor C59;
[0038] The first end of the first one hundred resistors R100 is electrically connected to the output end of the second operational amplifier U5-A and the output end of the third operational amplifier U5-B, and the second end of the first one hundred resistors R100 is electrically connected to the AD detection end of the MCU;
[0039] A first end of the fifty-ninth capacitor C59 is electrically connected to a second end of the first one hundred resistor R100, and a second end of the fifty-ninth capacitor C59 is grounded.
[0040] In the second aspect, an embodiment of the utility model also provides an AC charging pile, including a live wire, a neutral wire and a leakage current detection circuit for the AC charging pile as in any of the above embodiments, wherein the first input end of the zero-sequence current transformer is electrically connected to the live wire, and the second input end of the zero-sequence current transformer is electrically connected to the neutral wire.
[0041] The technical solution of the second aspect of the utility model has at least one of the following advantages or beneficial effects:
[0042] The AC charging pile uses the leakage current detection circuit for the AC charging pile of any of the above-mentioned embodiments. The zero-sequence current transformer is mounted on the L / N line of the output power supply line of the AC charging pile to sample the leakage current. The sampled current signal is converted into an AC voltage signal through the 109th resistor R109 of the conversion circuit, and then the extremely weak sampling signal is amplified dozens of times through the first operating amplifier U4-A and given to the AD detection end of the MCU. When the leakage current is small, the actual leakage current value can be quickly detected to ensure the safety of the car and personnel. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0044] Figure 1 A schematic diagram of an AC charging pile provided by the utility model;
[0045] Figure 2 A schematic diagram of another AC charging pile provided by the utility model;
[0046] Figure 3 A circuit diagram of a leakage current detection circuit for an AC charging pile provided by the utility model. DETAILED DESCRIPTION
[0047] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0049] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined.
[0050] In this specification, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being “above”, “above”, and “above” a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0051] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0052] The utility model proposes a leakage current detection circuit for an AC charging pile and an AC charging pile. A zero-sequence current transformer is sleeved on the L / N line of the output power supply line of the AC charging pile to sample the leakage current. The sampled current signal is converted into an AC voltage signal through the one hundred and ninth resistor R109 of the conversion circuit. The extremely weak sampling signal is amplified by dozens of times through the first operating amplifier U4-A and given to the AD detection end of the MCU. When the leakage current is small, the actual leakage current value can be quickly detected to ensure the safety of the car and personnel.
[0053] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings.
[0054] In one embodiment, referring to Figure 1 and Figure 3 , Figure 1 A schematic diagram of an AC charging pile provided by an embodiment of the utility model, Figure 3A circuit diagram of a leakage current detection circuit for an AC charging pile provided for an embodiment of the utility model, the leakage current detection circuit for an AC charging pile includes a zero-sequence current transformer, a conversion circuit, an operation amplifier circuit, a precision rectifier circuit and an MCU; the first input end of the zero-sequence current transformer is electrically connected to the live wire of the AC charging pile, and the second input end of the zero-sequence current transformer is electrically connected to the neutral wire of the AC charging pile; the conversion circuit includes a 109th resistor R109, the first end of the 109th resistor R109 is electrically connected to the first output end of the zero-sequence current transformer , the second end of the first one hundred and nine resistors R109 is electrically connected to the second output end of the zero-sequence current transformer; the operation amplifier circuit includes a first operation amplifier U4-A, the first input end of the first operation amplifier U4-A is electrically connected to the first output end of the zero-sequence current transformer, and the second input end of the first operation amplifier U4-A is electrically connected to the second output end of the zero-sequence current transformer; the input end of the precision rectifier circuit is electrically connected to the output end of the first operation amplifier U4-A; the AD detection end of the MCU is electrically connected to the output end of the precision rectifier circuit. The zero-sequence current transformer is mounted on the L / N line of the output power line of the AC charging pile, and the leakage current is sampled. The sampled current signal is converted into an AC voltage signal through the first one hundred and nine resistors R109 of the conversion circuit, and then the extremely weak sampling signal is amplified by dozens of times through the first operation amplifier U4-A, and is given to the AD detection end of the MCU. When the leakage current is small, the actual leakage current value can be quickly detected to ensure the safety of the car and personnel.
[0055] In one embodiment, the precision rectifier circuit includes: a second operational amplifier U5-A and a third operational amplifier U5-B, wherein the first input terminal of the second operational amplifier U5-A is electrically connected to the output terminal of the first operational amplifier U4-A, the second input terminal of the second operational amplifier U5-A is grounded, and the output terminal of the second operational amplifier U5-A is electrically connected to the AD detection terminal of the MCU; the first input terminal of the third operational amplifier U5-B is electrically connected to the output terminal of the first operational amplifier U4-A, and the second input terminal and output terminal of the third operational amplifier U5-B are electrically connected to the AD detection terminal of the MCU.
[0056] Specifically, the second operational amplifier U5-A and the third operational amplifier U5-B rectify the 50-60 Hz AC signal into a DC steamed wave signal.
[0057] In one embodiment, the precision rectifier circuit also includes a one-hundred-and-seventh resistor R107, a one-hundred-and-fourth resistor R104, a one-hundred-and-three resistor R103, a ninety-eighth resistor R98, a sixteenth diode D16 and a seventeenth diode D17; the first end of the one-hundred-and-seventh resistor R107 is electrically connected to the output end of the first operational amplifier U4-A, and the second end of the one-hundred-and-seventh resistor R107 is electrically connected to the first end of the one-hundred-and-fourth resistor R104; the first input end of the second operational amplifier U5-A is electrically connected to the second end of the one-hundred-and-fourth resistor R104, the first end of the one-hundred-and-three resistor R103 and the first end of the ninety-eighth resistor R98; the output end of the second operational amplifier U5-A is electrically connected to the cathode of the sixteenth diode D16 and the anode of the seventeenth diode D17; the anode of the sixteenth diode D16 is electrically connected to the second end of the ninety-eighth resistor R98; the cathode of the seventeenth diode D17 and the second end of the one-hundred-and-three resistor R103 are electrically connected to the AD detection end of the MCU.
[0058] In one embodiment, in order to adjust the DC steamed bun wave signal to a positive unidirectional DC steamed bun wave signal, the precision rectifier circuit also includes a one-hundred-sixth resistor R106, a one-hundred-fifth resistor R105, a fourteenth diode D14 and a fifteenth diode D15; the first input terminal of the third operational amplifier U5-B is electrically connected to the second end of the one-hundred-seventh resistor R107; the second input terminal of the third operational amplifier U5-B is electrically connected to the first end of the one-hundred-sixth resistor R106 and the first end of the one-hundred-fifth resistor R105, the second end of the one-hundred-sixth resistor R106 is electrically connected to the anode of the fifteenth diode D15, and the second end of the one-hundred-fifth resistor R105 is electrically connected to the AD detection terminal of the MCU; the output terminal of the third operational amplifier U5-B is electrically connected to the cathode of the fifteenth diode D15 and the anode of the fourteenth diode D14, and the cathode of the fourteenth diode D14 is electrically connected to the AD detection terminal of the MCU.
[0059] In one embodiment, the precision rectifier circuit further includes a ninety-ninth resistor R99, a first end of the ninety-ninth resistor R99 is electrically connected to the second input end of the second operational amplifier U5-A, and a second end of the ninety-ninth resistor R99 is electrically connected.
[0060] In one embodiment, the operating amplifier circuit also includes a one-hundred-and-first resistor R101, a one-hundred-and-second resistor R102, a one-hundred-and-eighth resistor R108 and a one-hundred-and-fourteenth resistor R114; the first end of the one-hundred-and-first resistor R101 is electrically connected to the second output end of the zero-sequence current transformer, and the second end of the one-hundred-and-first resistor R101 is electrically connected to the second input end of the first operating amplifier U4-A; the first end of the one-hundred-and-second resistor R102 is electrically connected to the second end of the one-hundred-and-first resistor R101, and the second end of the one-hundred-and-second resistor R102 is grounded; the first end of the one-hundred-and-fourteenth resistor R114 is electrically connected to the first output end of the zero-sequence current transformer, and the second end of the one-hundred-and-fourteenth resistor R114 is electrically connected to the first input end of the first operating amplifier U4-A; the first end of the one-hundred-and-eighth resistor R108 is electrically connected to the second end of the one-hundred-and-fourteenth resistor R114, and the second end of the one-hundred-and-eighth resistor R108 is electrically connected to the output end of the first operating amplifier U4-A.
[0061] In one embodiment, in order to ensure current stability, the operating amplifier circuit also includes a fifty-fifth capacitor C55 and a sixty-second capacitor C62; the first end of the fifty-fifth capacitor C55 is electrically connected to the first end of the first-hundred-and-one resistor R101, the first end of the sixty-second capacitor C62 is electrically connected to the first end of the first-hundred-fourteenth resistor R114, and the second end of the fifty-fifth capacitor C55 and the second end of the sixty-second capacitor C62 are grounded.
[0062] In one embodiment, the operating amplifier circuit also includes a sixtieth capacitor C60 and a sixty-first capacitor C61; the first end of the sixtieth capacitor C60 is electrically connected to the first input terminal of the first operating amplifier U4-A, and the second end of the sixtieth capacitor C60 is grounded; the first end of the sixty-first capacitor C61 is electrically connected to the first input terminal of the first operating amplifier U4-A, and the second end of the sixty-first capacitor C61 is electrically connected to the output terminal of the first operating amplifier U4-A.
[0063] In one embodiment, referring to Figure 2 and Figure 3 The leakage current detection circuit for the AC charging pile also includes a filtering circuit, which includes a first-hundredth resistor R100 and a fifty-ninth capacitor C59; the first end of the first-hundredth resistor R100 is electrically connected to the output end of the second operational amplifier U5-A and the output end of the third operational amplifier U5-B, and the second end of the first-hundredth resistor R100 is electrically connected to the AD detection end of the MCU; the first end of the fifty-ninth capacitor C59 is electrically connected to the second end of the first-hundredth resistor R100, and the second end of the fifty-ninth capacitor C59 is grounded.
[0064] Specifically, the one hundredth resistor R100 and the fifty-ninth capacitor C59 filter the DC steamed wave signal into a smooth DC voltage signal, and provide it to the AD detection terminal of the MCU.
[0065] Another embodiment of the utility model also provides an AC charging pile, including a live wire, a neutral wire and a leakage current detection circuit for an AC charging pile as in any of the above embodiments, wherein the first input end of the zero-sequence current transformer is electrically connected to the live wire, and the second input end of the zero-sequence current transformer is electrically connected to the neutral wire. The AC charging pile uses the leakage current detection circuit for an AC charging pile in any of the above embodiments, and the zero-sequence current transformer is sleeved on the L / N line of the output power supply line of the AC charging pile, and the leakage current is sampled. The sampled current signal is converted into an AC voltage signal through the 109th resistor R109 of the conversion circuit, and then the extremely weak sampling signal is amplified by dozens of times through the first operating amplifier U4-A, and is given to the AD detection end of the MCU. When the leakage current is small, the actual leakage current value can be quickly detected to ensure the safety of the car and personnel.
[0066] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed method above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or may be implemented as hardware, or may be implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. In addition, it is well known to those skilled in the art that communication media generally contain computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.
[0067] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present invention. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present invention.
Claims
1. A leakage current detection circuit for an AC charging pile, characterized in that: include: A zero-sequence current transformer, wherein a first input end of the zero-sequence current transformer is electrically connected to the live wire of the AC charging pile, and a second input end of the zero-sequence current transformer is electrically connected to the neutral wire of the AC charging pile; The conversion circuit comprises a one-hundred-ninth resistor R109, wherein a first end of the one-hundred-ninth resistor R109 is electrically connected to a first output end of the zero-sequence current transformer, and a second end of the one-hundred-ninth resistor R109 is electrically connected to a second output end of the zero-sequence current transformer; An operation amplifier circuit, the operation amplifier circuit comprising a first operation amplifier U4-A, a first input end of the first operation amplifier U4-A is electrically connected to a first output end of the zero-sequence current transformer, and a second input end of the first operation amplifier U4-A is electrically connected to a second output end of the zero-sequence current transformer; A precision rectifier circuit, wherein an input end of the precision rectifier circuit is electrically connected to an output end of the first operational amplifier U4-A; MCU, the AD detection end of the MCU is electrically connected to the output end of the precision rectifier circuit.
2. The leakage current detection circuit for an AC charging pile according to claim 1, characterized in that: The precision rectifier circuit comprises: A second operational amplifier U5-A, wherein a first input terminal of the second operational amplifier U5-A is electrically connected to an output terminal of the first operational amplifier U4-A, a second input terminal of the second operational amplifier U5-A is grounded, and an output terminal of the second operational amplifier U5-A is electrically connected to an AD detection terminal of the MCU; A third operational amplifier U5-B, wherein the first input terminal of the third operational amplifier U5-B is electrically connected to the output terminal of the first operational amplifier U4-A, and the second input terminal and output terminal of the third operational amplifier U5-B are electrically connected to the AD detection terminal of the MCU.
3. The leakage current detection circuit for an AC charging pile according to claim 2, characterized in that: The precision rectifier circuit further includes a one hundred and seventh resistor R107, a one hundred and fourth resistor R104, a one hundred and third resistor R103, a ninety-eighth resistor R98, a sixteenth diode D16 and a seventeenth diode D17; The first end of the first one hundred and seventh resistor R107 is electrically connected to the output end of the first operational amplifier U4-A, and the second end of the first one hundred and seventh resistor R107 is electrically connected to the first end of the first one hundred and fourth resistor R104; The first input terminal of the second operational amplifier U5-A is electrically connected to the second terminal of the first-hundred-and-fourth resistor R104, the first terminal of the first-hundred-and-threeth resistor R103, and the first terminal of the ninety-eighth resistor R98; The output terminal of the second operational amplifier U5-A is electrically connected to the cathode of the sixteenth diode D16 and the anode of the seventeenth diode D17; An anode of the sixteenth diode D16 is electrically connected to a second end of the ninety-eighth resistor R98; The cathode of the seventeenth diode D17 and the second end of the first one hundred and third resistor R103 are electrically connected to the AD detection end of the MCU.
4. The leakage current detection circuit for an AC charging pile according to claim 3, characterized in that: The precision rectifier circuit further includes a one hundred and sixth resistor R106, a one hundred and fifth resistor R105, a fourteenth diode D14 and a fifteenth diode D15; The first input terminal of the third operational amplifier U5-B is electrically connected to the second terminal of the first one hundred and seventh resistor R107; The second input terminal of the third operational amplifier U5-B is electrically connected to the first end of the first one hundred and sixth resistor R106 and the first end of the first one hundred and fifth resistor R105, the second end of the first one hundred and sixth resistor R106 is electrically connected to the anode of the fifteenth diode D15, and the second end of the first one hundred and fifth resistor R105 is electrically connected to the AD detection terminal of the MCU; The output end of the third operational amplifier U5-B is electrically connected to the cathode of the fifteenth diode D15 and the anode of the fourteenth diode D14, and the cathode of the fourteenth diode D14 is electrically connected to the AD detection end of the MCU.
5. The leakage current detection circuit for an AC charging pile according to claim 4, characterized in that: The precision rectification circuit also includes a ninety-ninth resistor R99, a first end of the ninety-ninth resistor R99 is electrically connected to the second input end of the second operational amplifier U5-A, and a second end of the ninety-ninth resistor R99 is electrically connected.
6. The leakage current detection circuit for an AC charging pile according to claim 1, characterized in that: The operation amplifier circuit further includes a one hundred and first resistor R101, a one hundred and second resistor R102, a one hundred and eighth resistor R108 and a one hundred and fourteenth resistor R114; The first end of the first one hundred and first resistor R101 is electrically connected to the second output end of the zero-sequence current transformer, and the second end of the first one hundred and first resistor R101 is electrically connected to the second input end of the first operational amplifier U4-A; The first end of the first one hundred and second resistor R102 is electrically connected to the second end of the first one hundred and first resistor R101, and the second end of the first one hundred and second resistor R102 is grounded; The first end of the 114th resistor R114 is electrically connected to the first output end of the zero-sequence current transformer, and the second end of the 114th resistor R114 is electrically connected to the first input end of the first operational amplifier U4-A; The first end of the first-hundred-eighth resistor R108 is electrically connected to the second end of the first-hundred-fourteenth resistor R114, and the second end of the first-hundred-eighth resistor R108 is electrically connected to the output end of the first operational amplifier U4-A.
7. The leakage current detection circuit for an AC charging pile according to claim 6, characterized in that: The operation amplifier circuit further includes a fifty-fifth capacitor C55 and a sixty-second capacitor C62; A first end of the fifty-fifth capacitor C55 is electrically connected to a first end of the first-hundred-and-first resistor R101, a first end of the sixty-second capacitor C62 is electrically connected to a first end of the first-hundred-and-fourteenth resistor R114, and a second end of the fifty-fifth capacitor C55 and a second end of the sixty-second capacitor C62 are grounded.
8. The leakage current detection circuit for an AC charging pile according to claim 6, characterized in that: The operation amplifier circuit further includes a sixtieth capacitor C60 and a sixty-first capacitor C61; A first end of the sixtieth capacitor C60 is electrically connected to the first input end of the first operational amplifier U4-A, and a second end of the sixtieth capacitor C60 is grounded; The first end of the sixty-first capacitor C61 is electrically connected to the first input end of the first operational amplifier U4-A, and the second end of the sixty-first capacitor C61 is electrically connected to the output end of the first operational amplifier U4-A.
9. The leakage current detection circuit for an AC charging pile according to claim 2, characterized in that: The leakage current detection circuit for the AC charging pile further includes a filter circuit, and the filter circuit includes a 100th resistor R100 and a 59th capacitor C59; The first end of the first one hundred resistors R100 is electrically connected to the output end of the second operational amplifier U5-A and the output end of the third operational amplifier U5-B, and the second end of the first one hundred resistors R100 is electrically connected to the AD detection end of the MCU; A first end of the fifty-ninth capacitor C59 is electrically connected to a second end of the first one hundred resistor R100, and a second end of the fifty-ninth capacitor C59 is grounded.
10. An AC charging pile, characterized in that: It comprises a live wire, a neutral wire and a leakage current detection circuit for an AC charging pile as described in any one of claims 1 to 9, wherein the first input end of the zero-sequence current transformer is electrically connected to the live wire, and the second input end of the zero-sequence current transformer is electrically connected to the neutral wire.