Leakage detection circuit, on-vehicle charger, vehicle

Abstract

The utility model discloses a kind of leakage detection circuit, vehicle charger, vehicle, involve vehicle technical field.Circuit includes: first diode, the positive pole of first diode is connected with the fire wire of to-be-detected ac port;Second diode, the positive pole of second diode is connected with the zero line of to-be-detected ac port;First resistance, the first end of first resistance is connected with the negative pole of first diode and second diode;Operational amplifier, the second end of first resistance is connected with the inverting input end of operational amplifier, output end connects microcontroller;Second resistance, the first end of second resistance is connected with the inverting input end of operational amplifier, second end connects the output end of operational amplifier;Third resistance, the first end of third resistance is connected with the ground wire of to-be-detected ac port, second end connects the noninverting input end of operational amplifier;Fourth resistance, the first end of fourth resistance is connected with the second end of third resistance, second end connects first ground end.The circuit can be realized to to-be-detected ac port leakage detection.

Description

Technical Field

[0001] This utility model relates to the field of vehicle technology, and in particular to a leakage current detection circuit, an on-board charger, and a vehicle. Background Technology

[0002] With the rapid development of the new energy electric vehicle industry, the market demand for on-board chargers is constantly expanding, and the industry's development prospects are promising. As the demand for on-board chargers grows, the functional requirements for them are also increasing, and the use of bidirectional on-board chargers is becoming more widespread.

[0003] When the bidirectional on-board charger is discharging AC power, the insulation between the AC side wiring and the vehicle ground is crucial to the product's performance and safety. Abnormal insulation between the AC side wiring and the ground wire may damage the device or cause electric shock to personnel. Therefore, leakage current detection of the AC port of the on-board charger is necessary. Utility Model Content

[0004] The present invention aims to at least partially solve one of the technical problems in the related art. Therefore, the first objective of the present invention is to provide a leakage current detection circuit for detecting leakage current at AC ports.

[0005] The second objective of this utility model is to provide an on-board charger.

[0006] The third objective of this utility model is to propose a vehicle.

[0007] To achieve the above objectives, the first aspect of this utility model provides a leakage current detection circuit, the circuit comprising: a first diode, the anode of the first diode being connected to the live wire of the AC port to be detected; a second diode, the anode of the second diode being connected to the neutral wire of the AC port to be detected; a first resistor, the first end of the first resistor being connected to the cathode of the first diode and the cathode of the second diode; an operational amplifier, the inverting input terminal of the operational amplifier being connected to the second end of the first resistor, and the output terminal of the operational amplifier being connected to a microcontroller; a second resistor, the first end of the second resistor being connected to the inverting input terminal of the operational amplifier, and the second end of the second resistor being connected to the output terminal of the operational amplifier; a third resistor, the first end of the third resistor being connected to the ground wire of the AC port to be detected, and the second end of the third resistor being connected to the non-inverting input terminal of the operational amplifier; and a fourth resistor, the first end of the fourth resistor being connected to the second end of the third resistor, and the second end of the fourth resistor being connected to a first ground terminal.

[0008] In addition, the leakage current detection circuit according to this utility model may also have the following technical features: In some examples, the circuit further includes: a third resistor, the first end of which is connected to the ground of the AC port to be tested, and the second end of which is connected to the non-inverting input of the operational amplifier; a fourth resistor, the first end of which is connected to the second end of the third resistor, and the second end of which is connected to a first ground; a fifth resistor, the first end of which is connected to the output of the operational amplifier, and the second end of which is connected to the first ground; and a sixth resistor, the first end of which is connected to the output of the operational amplifier, and the second end of which is connected to the microcontroller.

[0009] In some examples, the circuit further includes: a third diode, the anode of which is connected to the second terminal of the sixth resistor, and the cathode of which is connected to a preset DC power supply; and a fourth diode, the cathode of which is connected to the second terminal of the sixth resistor, and the anode of which is connected to the second low terminal.

[0010] In some examples, the circuit further includes a capacitor, the first end of which is connected to the second end of the sixth resistor, and the second end of which is connected to a first ground terminal.

[0011] In some examples, the circuit further includes a Zener diode, the negative terminal of which is connected to the second terminal of the first resistor, and the positive terminal of which is connected to a second ground terminal.

[0012] In some examples, the circuit further includes: a first switch, a first end of which is connected to a first end of the first resistor, and a second end of which is connected to the live wire and the neutral wire.

[0013] In some examples, the circuit further includes: a second switch, the first end of which is connected to the live wire and the second end of which is connected to the neutral wire; and a seventh resistor, the first end of which is connected to the second end of the second switch and the second end of which is connected to the ground wire.

[0014] In some examples, the first switch includes a first relay, and the second switch includes a second relay.

[0015] To achieve the above objectives, the second aspect of this utility model provides an on-board charger, including the aforementioned leakage detection circuit.

[0016] To achieve the above objectives, the third aspect of this utility model provides a vehicle including the aforementioned on-board charger.

[0017] The leakage current detection circuit, on-board charger, and vehicle according to this utility model include: a first diode, the anode of which is connected to the live wire of the AC port to be tested; a second diode, the anode of which is connected to the neutral wire of the AC port to be tested; a first resistor, the first end of which is connected to the cathode of the first diode and the cathode of the second diode; an operational amplifier, the inverting input of which is connected to the second end of the first resistor, and the output of which is connected to a microcontroller; a second resistor, the first end of which is connected to the inverting input of the operational amplifier, and the second end of which is connected to the output of the operational amplifier; a third resistor, the first end of which is connected to the ground wire of the AC port to be tested, and the second end of which is connected to the non-inverting input of the operational amplifier; and a fourth resistor, the first end of which is connected to the second end of the third resistor, and the second end of which is connected to the first ground terminal. Thus, leakage current detection of the AC port can be achieved.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of the leakage current detection circuit according to an embodiment of the present invention; Figure 2 This is a circuit diagram of the AC port load side of an embodiment of this utility model; Figure 3 This is a circuit diagram of the AC port of one embodiment of this utility model; Figure 4 This is a schematic diagram of the voltage between the live wire and the ground wire of an AC port, as an example of this utility model. Figure 5 This is a schematic diagram of the voltage between the neutral wire and the ground wire of an AC port, as an example of this utility model. Figure 6 This is a schematic diagram of a microcontroller sampling voltage as an example of this utility model; Figure 7 This is a schematic diagram of the voltage between the live wire and the ground wire of an AC port, which is another example of this utility model. Figure 8 This is a schematic diagram of the voltage between the neutral and ground wires of an AC port, representing another example of this utility model. Figure 9 This is a schematic diagram of the microcontroller sampling voltage, another example of this utility model; Figure 10 This is a circuit diagram of a leakage current detection circuit according to another embodiment of the present invention; Figure 11 This is a circuit diagram of the AC port of another embodiment of this utility model; Figure 12 This is a flowchart of the leakage current detection circuit according to an embodiment of the present invention; Figure 13 This is a structural block diagram of the on-board charger according to an embodiment of the present utility model; Figure 14 This is a structural block diagram of the vehicle according to an embodiment of the present utility model. Detailed Implementation

[0020] The following description, with reference to the accompanying drawings, describes a leakage current detection circuit, an on-board charger, and a vehicle according to embodiments of the present invention, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described with reference to the accompanying drawings are exemplary and should not be construed as limiting the present invention.

[0021] The following is for reference. Figures 1-12 The leakage current detection circuit 10 of this utility model embodiment is described.

[0022] like Figures 1-12 As shown, the leakage current detection circuit 10 includes: a first diode D1, the anode of which is connected to the live wire AC-L of the AC port to be tested; a second diode D2, the anode of which is connected to the neutral wire AC-N of the AC port to be tested; a first resistor R1, the first end of which is connected to the cathode of the first diode D1 and the cathode of the second diode D2; an operational amplifier U1, the inverting input of which is connected to the second end of the first resistor R1, and the output of which is connected to a microcontroller; and a second resistor R2, the first end of which is connected to the inverting input of the operational amplifier U1, and the second end of which is connected to the output of the operational amplifier U1. ACLD-test is the sampling port of the microcontroller, through which the microcontroller obtains the output voltage of operational amplifier U1; the third resistor R3, the first end of the third resistor R3 is connected to the ground AC-PE of the AC port to be tested, and the second end of the third resistor R3 is connected to the non-inverting input terminal of operational amplifier U1; the fourth resistor R4, the first end of the fourth resistor R4 is connected to the second end of the third resistor R3, and the second end of the fourth resistor R4 is connected to the first ground terminal PGND.

[0023] Specifically, the aforementioned AC ports to be tested include the load-side live wire, the load-side neutral wire, the product-side live wire, and the product-side neutral wire.

[0024] The aforementioned load-side live wire and load-side neutral wire refer to the live wire input terminal and neutral wire input terminal of the device that obtains power using the AC port under test.

[0025] The aforementioned live wire and neutral wire of the product end refer to the live wire output terminal and neutral wire output terminal of the device that uses the AC port under test to transmit electrical energy.

[0026] For the aforementioned load terminal live wire, there is a first equivalent capacitance between it and the ground wire AC-PE of the AC port to be tested.

[0027] For the aforementioned load-side neutral wire, there is a second equivalent capacitance between it and the ground wire AC-PE of the AC port to be tested.

[0028] For the live wire of the aforementioned product, there is a third equivalent capacitance between it and the ground wire AC-PE of the AC port to be tested.

[0029] For the neutral wire of the above-mentioned product terminal, there is a fourth equivalent capacitance between it and the ground wire AC-PE of the AC port to be tested.

[0030] It should be noted that when the device that obtains power from the AC port under test is connected to the device that outputs power from the AC port under test, the live wire of the load end and the live wire of the product end are one live wire, which is the live wire AC-L of the AC port under test, and the neutral wire of the load end and the neutral wire of the product end are one neutral wire, which is the neutral wire AC-N of the AC port under test.

[0031] At this point, the load side can refer to Figure 2 For product details, please refer to [link / reference]. Figure 3 .exist Figure 2 In this context, CYLX represents the first equivalent capacitance mentioned above, and CYNX represents the second equivalent capacitance mentioned above. Figure 3 In this context, CYL represents the third equivalent capacitance, CYN represents the fourth equivalent capacitance, and RLD represents the AC-to-ground leakage equivalent resistance.

[0032] The working principle of the leakage current detection circuit 10 described above will be explained in detail below.

[0033] make Let the voltage between the live wire AC-L and the neutral wire AC-N of the AC port to be tested be... Let the voltage between the live wire AC-L and the ground wire AC-PE of the AC port to be tested be... Let the voltage between the neutral wire AC-N and the ground wire AC-PE of the AC port to be tested be... This is the sampling voltage of the microcontroller.

[0034] When there is no leakage current at the AC port to be tested, the resistance value of the AC to ground equivalent resistance RLD is infinite.

[0035] At this time, the waveforms of the live wire AC-L and the ground wire AC-PE of the AC port under test are symmetrical with those of the neutral wire AC-N and the ground wire AC-PE of the AC port under test. The capacitance value of the first equivalent capacitor CYLX is the same as that of the second equivalent capacitor CYNX, and the capacitance value of the third equivalent capacitor CYL is the same as that of the fourth equivalent capacitor CYN.

[0036] definition The voltage value is as follows: .

[0037] Where Vac is the preset voltage parameter value, and t is time.

[0038] but The voltage value is as follows: , The voltage value is as follows: , in, This refers to the capacitance value after the third equivalent capacitance CYL and the first equivalent capacitance CYLX are connected in parallel. This means the capacitance value after the fourth equivalent capacitance CYN and the second equivalent capacitance CYNX are connected in parallel.

[0039] At this point, since the capacitance value of the first equivalent capacitor CYLX is the same as the capacitance value of the second equivalent capacitor CYNX, and the capacitance value of the third equivalent capacitor CYL is the same as the capacitance value of the fourth equivalent capacitor CYN, therefore... = This makes the above With the above The specific value is 0.5.

[0040] Specifically, when no leakage occurs, the above See also Figure 4 and Figure 5 .

[0041] It is evident that when there is no leakage current at the AC port under test, = =0.5× .

[0042] Due to the above voltage The voltage of the signal on the live wire AC-L, the above voltage The voltage of the signal on the neutral line AC-N is such that even if the two signals are in phase, their directions are opposite at any given moment.

[0043] When the AC current in the live wire AC-L and the neutral wire AC-N is at the positive half-axis of the AC voltage, the signal in the live wire AC-L will pass through the first diode D1, and the signal in the neutral wire AC-N will be filtered by the second diode D2. At this time, the signal in the live wire AC-L will reach the negative feedback system composed of the first resistor R1, the second resistor R2, and the operational amplifier U1. The voltage of this signal will be amplified and reach the microcontroller. Specifically, the voltage reaching the microcontroller is: , Wherein, K11 is the amplification factor of the input signal by the negative feedback system composed of the operational amplifier U1.

[0044] When the AC current in the live wire AC-L and the neutral wire AC-N is on the negative half-axis of the AC voltage, the signal in the neutral wire AC-N will pass through the second diode D2, while the signal in the live wire AC-L will be filtered by the first diode D1. At this time, the signal in the neutral wire AC-N will reach the negative feedback system composed of the first resistor R1, the second resistor R2, and the operational amplifier U1. The voltage of this signal will be amplified and reach the microcontroller. Specifically, the voltage reaching the microcontroller is: .

[0045] As can be seen, when there is no leakage current at the AC port under test, the signal received by the microcontroller The voltage peak value during the positive half-cycle is consistent with the voltage peak value during the negative half-cycle; see details in [link to relevant documentation]. Figure 6 .

[0046] When leakage occurs at the AC port to be tested, the resistance value of the AC-to-ground leakage equivalent resistance RLD is not infinite.

[0047] At this time, the waveforms of the live wire AC-L and the ground wire AC-PE of the AC port under test are asymmetrical with those of the neutral wire AC-N and the ground wire AC-PE of the AC port under test.

[0048] Similarly, definition The voltage value is as follows: .

[0049] but The voltage value is as follows: , The voltage value is as follows: , in, It means the impedance value that varies with frequency obtained by connecting the third equivalent capacitor CYL, the first equivalent capacitor CYLX, and the AC ground leakage equivalent resistance RLD in parallel.

[0050] Specifically, when a leakage occurs, the above See also Figure 7 and Figure 8 .

[0051] It is evident that when leakage occurs at the AC port under test, ≠ ≠0.5× .

[0052] When the AC current in the live wire AC-L and the neutral wire AC-N is at the positive half-axis of the AC voltage, the signal in the live wire AC-L will pass through the first diode D1, and the signal in the neutral wire AC-N will be filtered by the second diode D2. At this time, the signal in the live wire AC-L will reach the negative feedback system composed of the first resistor R1, the second resistor R2, and the operational amplifier U1. The voltage of this signal will be amplified and reach the microcontroller. Specifically, the voltage reaching the microcontroller is: .

[0053] When the AC current in the live wire AC-L and the neutral wire AC-N is on the negative half-axis of the AC voltage, the signal in the neutral wire AC-N will pass through the second diode D2, and the signal in the live wire AC-L will be filtered by the first diode D1. At this time, the signal in the neutral wire AC-N will reach the negative feedback system composed of the first resistor R1, the second resistor R2, and the operational amplifier U1. The voltage of this signal will be amplified and reach the microcontroller. Specifically, the voltage reaching the microcontroller is: .

[0054] It can be seen that when leakage occurs at the AC port under test, the microcontroller receives the signal... The voltage peak value during the positive half-cycle is inconsistent with the voltage peak value during the negative half-cycle; see details below. Figure 9 .

[0055] In other words, when the microcontroller receives a signal Then, acquire the signal. If the voltage peak value during the positive half-cycle and the voltage peak value during the negative half-cycle are the same, it indicates that the AC port under test has no leakage current. If the two voltage peak values ​​are different, it indicates that the AC port under test has leakage current.

[0056] This allows for leakage current detection at AC ports.

[0057] It should be noted that, in the above Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 In the graph, the horizontal axis represents time in seconds, and the vertical axis represents voltage in volts. Figure 6 and Figure 9 In the diagram, the left vertical axis is the one used by VLN(t), representing the actual voltage, and the right vertical axis is the one used by CLD_test(t), representing the sampled voltage obtained by the microcontroller. As an example, when the actual voltage of the AC port is 200V, the sampled voltage obtained by the microcontroller is 1V, and when the actual voltage of the AC port is -400V, the sampled voltage obtained by the microcontroller is -2V.

[0058] In some embodiments of this utility model, the leakage current detection circuit 10 further includes: a fifth resistor R5, the first end of which is connected to the output terminal of the operational amplifier U1, and the second end of which is connected to the first ground terminal PGND; and a sixth resistor R6, the first end of which is connected to the output terminal of the operational amplifier U1, and the second end of which is connected to the microcontroller.

[0059] The fifth resistor R5 mentioned above is the output matching resistor for the differential operational amplifier U1, and the sixth resistor R6 mentioned above is the sampling filter resistor.

[0060] In some embodiments of this utility model, the leakage current detection circuit 10 further includes: a third diode D3, the anode of the third diode D3 being connected to the second terminal of the sixth resistor R6, and the cathode of the third diode D3 being connected to a preset DC power supply P3.3VA; and a fourth diode D4, the cathode of the fourth diode being connected to the second terminal of the sixth resistor R6, and the anode of the fourth diode D4 being connected to the second low terminal.

[0061] Overvoltage protection can be achieved by setting the third diode D3 and the fourth diode D4 as described above.

[0062] In some embodiments of this utility model, the leakage current detection circuit 10 further includes: a capacitor C1, the first end of which is connected to the second end of the sixth resistor R6, and the second end of which is connected to the first ground terminal PGND.

[0063] The capacitor C1 mentioned above is the sampling filter capacitor.

[0064] In some embodiments of this utility model, the leakage current detection circuit 10 further includes: a Zener diode TVS1, the negative terminal of which is connected to the second end of the first resistor R1, and the positive terminal of which is connected to the second ground terminal PAGND.

[0065] The aforementioned Zener diode TVS1 is an overvoltage protection stealing diode for the sampling port.

[0066] For the leakage current detection circuit 10 in the above embodiment, since the resistance of the first resistor R1 in the high-impedance differential sampling circuit is equal to the resistance of the third resistor R3, and the resistance of the second resistor R2 is equal to the resistance of the fourth resistor R4, the high-impedance differential sampling amplification factor is the resistance of the second resistor R2 divided by the resistance of the first resistor R1, that is, K11 = r2 / r1, where r1 is the resistance of the first resistor R1 and r2 is the resistance of the second resistor R2.

[0067] To meet the overall insulation resistance requirements, the insulation resistance between the live wire (AC-L) and the ground wire (AC-PE) of the AC port under test is generally required to be greater than 10MΩ. Enterprise standards require even higher values, exceeding 20MΩ. Therefore, the resistance values ​​of the first resistor R1 and the third resistor R3 need to be very large. For example, r1=r3=15MΩ, r2=r4=68KΩ, where r3 is the resistance value of the third resistor R3 and r4 is the resistance value of the fourth resistor R4. .

[0068] Therefore, in some embodiments of this utility model, the leakage current detection circuit 10 further includes: a first switch, the first end of the first switch being connected to the first end of the first resistor R1, and the second end of the first switch being connected to the live wire AC-L and the neutral wire AC-N.

[0069] Specifically, by setting a first switch, the first switch is closed when leakage current detection is needed and opened when leakage current detection is not needed. This ensures that the insulation impedance of the entire device is still met even with relatively small resistance values ​​for the first resistor R1 and the third resistor R3. This avoids interference with the microcontroller's sampling signal caused by a weak input signal to the operational amplifier U1 due to larger resistance values ​​of the first resistor R1 and the third resistor R3, thus preventing AC zero-crossing distortion and improving the linearity of the sampling results. As an example, after setting the first switch, the first resistor R1 can be a 1MΩ resistor. Compared to the 15MΩ resistor in the previous embodiment, this amplifies the current flowing into the input of the operational amplifier U1 by 15 times, thereby improving sampling accuracy.

[0070] For details of the aforementioned leakage current detection circuit 10, please refer to [link / reference needed]. Figure 10 The specific embodiment shown. In this specific embodiment, the first switch includes a first relay K1.

[0071] In some embodiments of this utility model, the leakage current detection circuit 10 further includes: a second switch, the first end of which is connected to the live wire AC-L, and the second end of which is connected to the neutral wire AC-N.

[0072] Specifically, by setting a second switch, when the second switch is closed, the capacitance value of the equivalent capacitance when there is no leakage current at the load end can be dynamically calculated, thereby improving the adaptability of leakage current detection.

[0073] For details of the aforementioned leakage current detection circuit 10, please refer to [link / reference needed]. Figure 11 The specific embodiment shown is as follows. In this specific embodiment, the first switch includes a first relay K1, the second switch includes a second relay K2, and the leakage current detection circuit 10 further includes a seventh resistor RX, the first end of the seventh resistor RX being connected to the second end of the second switch, and the second end of the seventh resistor RX being connected to the ground wire AC-PE.

[0074] In this specific embodiment, see Figure 12 After the leakage detection is activated, the first relay K1 is closed to determine if there is leakage. If there is leakage, leakage protection is activated and the information is reported.

[0075] If there is no leakage, close the second relay K2 and calculate the equivalent capacitance value.

[0076] Turn on the second relay K2 and continue leakage detection for 5 minutes. Then stop the leakage detection, turn on the first relay K1, set a timer for 20 minutes, and then start the leakage detection again.

[0077] The above-mentioned reverse calculation of the equivalent capacitance value is illustrated using the seventh resistor RX with a resistance of 100KΩ as an example.

[0078] Specifically, the equivalent capacitance value is calculated by reverse calculation using the following formula: , Among them, the capacitance of the third equivalent resistor CYL is equal to the capacitance of the fourth equivalent resistor CYN, and the capacitance of the first equivalent capacitor CYLX is equal to the capacitance of the second equivalent capacitor CYNX. This refers to the impedance value that varies with frequency, obtained by connecting the third equivalent capacitor CYL, the first equivalent capacitor CYLX, and the seventh resistor RX in parallel.

[0079] Since the capacitance values ​​of the third equivalent capacitance CYL and the fourth equivalent capacitance CYN are both known values ​​within the product, therefore, after obtaining... and Then, the capacitance values ​​of the first equivalent capacitance CYLX and the second equivalent capacitance CYNX can be obtained by reverse calculation based on the above formula.

[0080] In summary, the leakage current detection circuit of this utility model embodiment includes: a first diode, the anode of which is connected to the live wire of the AC port to be tested; a second diode, the anode of which is connected to the neutral wire of the AC port to be tested; a first resistor, the first end of which is connected to the cathode of the first diode and the cathode of the second diode; an operational amplifier, the inverting input terminal of which is connected to the second end of the first resistor, and the output terminal of which is connected to a microcontroller; a second resistor, the first end of which is connected to the inverting input terminal of the operational amplifier, and the second end of which is connected to the output terminal of the operational amplifier; a third resistor, the first end of which is connected to the ground wire of the AC port to be tested, and the second end of which is connected to the non-inverting input terminal of the operational amplifier; and a fourth resistor, the first end of which is connected to the second end of the third resistor, and the second end of which is connected to the first ground terminal. Therefore, leakage current detection of the AC port can be achieved.

[0081] Furthermore, this utility model proposes an on-board charger.

[0082] Figure 13 This is a structural block diagram of the on-board charger according to an embodiment of the present utility model.

[0083] like Figure 13 As shown, the on-board charger 100 includes the aforementioned leakage detection circuit 10.

[0084] The on-board charger of this utility model embodiment can realize leakage detection of AC port through the leakage detection circuit of the above embodiment.

[0085] Furthermore, this utility model proposes a vehicle.

[0086] Figure 14 This is a structural block diagram of the vehicle according to an embodiment of the present utility model.

[0087] like Figure 14 As shown, vehicle 1000 includes the aforementioned on-board charger 100.

[0088] The vehicle of this utility model embodiment can perform leakage current detection on the AC port through the on-board charger of the above embodiment.

[0089] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein can be considered as a ordered list of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0090] It should be understood that the various parts of this utility model can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0092] In the description of this specification, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as a limitation of this utility model.

[0093] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0094] In this specification, unless otherwise stated, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0095] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0096] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A leakage current detection circuit, characterized in that, The circuit includes: The first diode, the positive terminal of which is connected to the live wire of the AC port to be tested; The second diode, the positive terminal of which is connected to the neutral wire of the AC port to be tested; A first resistor, the first end of which is connected to the negative terminal of the first diode and the negative terminal of the second diode; An operational amplifier, wherein the inverting input terminal of the operational amplifier is connected to the second terminal of the first resistor, and the output terminal of the operational amplifier is connected to a microcontroller; The second resistor has its first end connected to the inverting input terminal of the operational amplifier and its second end connected to the output terminal of the operational amplifier. The third resistor has its first end connected to the ground wire of the AC port to be tested, and its second end connected to the non-inverting input terminal of the operational amplifier. A fourth resistor, the first end of which is connected to the second end of the third resistor, and the second end of the fourth resistor is connected to the first ground terminal.

2. The leakage current detection circuit according to claim 1, characterized in that, The circuit also includes: The fifth resistor has its first end connected to the output terminal of the operational amplifier and its second end connected to the first ground terminal. The sixth resistor has its first end connected to the output of the operational amplifier and its second end connected to the microcontroller.

3. The leakage current detection circuit according to claim 2, characterized in that, The circuit also includes: The third diode, the positive terminal of which is connected to the second terminal of the sixth resistor, and the negative terminal of which is connected to a preset DC power supply; The fourth diode has its cathode connected to the second terminal of the sixth resistor, and its anode connected to the second low terminal.

4. The leakage current detection circuit according to claim 2, characterized in that, The circuit also includes: A capacitor, the first end of which is connected to the second end of the sixth resistor, and the second end of which is connected to the first ground terminal.

5. The leakage current detection circuit according to claim 1, characterized in that, The circuit also includes: A Zener diode, wherein the negative terminal of the Zener diode is connected to the second terminal of the first resistor, and the positive terminal of the Zener diode is connected to the second ground terminal.

6. The leakage current detection circuit according to claim 1, characterized in that, The circuit also includes: A first switch, the first end of which is connected to the first end of the first resistor, and the second end of which is connected to the live wire and the neutral wire.

7. The leakage current detection circuit according to claim 6, characterized in that, The circuit also includes: A second switch, the first end of which is connected to the live wire, and the second end of which is connected to the neutral wire; The seventh resistor has its first end connected to the second end of the second switch, and its second end connected to the ground wire.

8. The leakage current detection circuit according to claim 7, characterized in that, The first switch includes a first relay, and the second switch includes a second relay.

9. An on-board charger, characterized in that, Includes a leakage current detection circuit according to any one of claims 1-8.

10. A vehicle, characterized in that, Includes the on-board charger according to claim 9.

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