Electric leakage detection circuit
By introducing a signal flipping circuit into the leakage current detection circuit, the negative half-cycle signal is flipped into a positive half-cycle signal that the processor can recognize, which solves the problem that the processor has difficulty recognizing the negative half-cycle signal, and achieves faster protection response and higher charging pile safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-03-31
AI Technical Summary
The processor in the existing leakage current detection circuit has difficulty recognizing the negative half-cycle signal, resulting in a longer protection time and reducing the safety of the charging pile.
A leakage current detection circuit is designed, including a leakage current detection ring, a sampling circuit, a protection circuit, a filtering circuit, an amplification circuit, a signal inversion circuit, and a processor. The signal inversion circuit inverts the negative half-cycle signal into a positive half-cycle signal that the processor can recognize.
The protection time of the leakage current detection circuit has been reduced, thus improving the safety of the charging pile.
Smart Images
Figure CN121763167A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of new energy technology, and in particular relates to a leakage current detection circuit. Background Technology
[0002] American standard AC charging piles have high requirements for protection time (i.e., the total time from when the leakage current detection circuit detects that the residual current has reached the protection threshold to when the protection action is executed to cut off the power to the main circuit). Since the time required to execute the protection action (such as controlling the relay to disconnect) is usually difficult to reduce, in order to reduce the protection time, it is usually necessary to reduce the time required to detect that the residual current has reached the protection threshold.
[0003] However, the processors in current leakage current detection circuits have difficulty recognizing negative half-cycle signals, which makes it take a long time to detect that the residual current has reached the protection threshold. This results in a longer protection time for current leakage current detection circuits, reducing the safety of charging piles. Summary of the Invention
[0004] In view of this, the present application provides a leakage current detection circuit to solve the technical problem that the long protection time of the leakage current detection circuit in the prior art leads to the low safety of the charging pile.
[0005] In a first aspect, embodiments of this application provide a leakage current detection circuit, including a leakage current detection ring, a sampling circuit, a protection circuit, a first filter circuit, a first amplification circuit, a second filter circuit, a second amplification circuit, a signal switching circuit, and a processor connected in sequence. The leakage current detection ring is connected to the leakage current transformer and is configured to obtain the residual current of the leakage current transformer; The sampling circuit is configured to convert the residual current into a first voltage signal; The protection circuit is configured to provide high-voltage protection for the leakage current detection circuit; The first filtering circuit is configured to filter high-frequency interference signals in the first voltage signal and to perform current limiting processing on the current signal corresponding to the first voltage signal to obtain and output the second voltage signal. The first amplifier circuit is configured to amplify the second voltage signal to obtain and output a third voltage signal within a first preset voltage range; The second filter circuit is configured to filter operational amplifier noise and high-frequency interference signals from the third voltage signal to obtain and output a fourth voltage signal; The second amplifier circuit is configured to amplify the fourth voltage signal to obtain and output a fifth voltage signal within a second preset voltage range; The signal flipping circuit is configured to flip the negative half-cycle signal in the fifth voltage signal to obtain and output the sixth voltage signal; The processor is configured to determine whether leakage has occurred based on the sixth voltage signal.
[0006] Optionally, the circuit further includes a self-test circuit; the self-test circuit is connected to the processor and the leakage current transformer respectively; The self-test circuit is configured to control the leakage current transformer to generate a simulated residual current after receiving a leakage current simulation command sent by the processor.
[0007] Optionally, the sampling circuit includes a first resistor and a second resistor. The first end of the first resistor and the first end of the second resistor are both connected to ground. The second end of the first resistor, the first output terminal of the leakage current detection ring, and the first input terminal of the protection circuit are all connected together. The second end of the second resistor, the second output terminal of the leakage current detection ring, and the second input terminal of the protection circuit are all connected together.
[0008] Optionally, the protection circuit includes a first diode and a second diode; the cathode of the first diode, the anode of the second diode, the first input terminal of the protection circuit, and the first output terminal of the protection circuit are all connected together, and the anode of the first diode, the cathode of the second diode, the second input terminal of the protection circuit, and the second output terminal of the protection circuit are all connected together.
[0009] Optionally, the first filter circuit includes a third resistor, a fourth resistor, a first capacitor, a second capacitor, and a third capacitor; the first end of the third resistor is connected to the first output terminal of the protection circuit, the second end of the third resistor, the first end of the first capacitor, the first end of the second capacitor, and the first output terminal of the first filter circuit are all connected together, the first end of the fourth resistor is connected to the second output terminal of the protection circuit, the second end of the fourth resistor, the second end of the first capacitor, the first end of the third capacitor, and the second output terminal of the first filter circuit are all connected together, and the second end of the second capacitor and the second end of the third capacitor are all connected to ground.
[0010] Optionally, the first amplification circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a first operational amplifier; the first end of the fifth resistor is connected to the first output terminal of the first filter circuit, the second end of the fifth resistor, the first end of the sixth resistor, and the inverting input terminal of the first operational amplifier are all connected together, the second end of the sixth resistor, the output terminal of the first operational amplifier, and the output terminal of the first amplification circuit are all connected together, the first end of the seventh resistor is connected to the second output terminal of the first filter circuit, the second end of the seventh resistor, the first end of the eighth resistor, and the non-inverting input terminal of the first operational amplifier are all connected together, and the second end of the eighth resistor is grounded.
[0011] Optionally, the second filter circuit includes a ninth resistor, a fourth capacitor, and a fifth capacitor; the first terminal of the fourth capacitor is connected to the output terminal of the first amplifier circuit, and the second terminal of the fourth capacitor, the first terminal of the ninth resistor, the first terminal of the fifth capacitor, and the output terminal of the second filter circuit are all connected together, with the second terminal of the ninth resistor and the second terminal of the fifth capacitor both connected to ground.
[0012] Optionally, the second amplifier circuit includes a sixth capacitor, a seventh capacitor, a second operational amplifier, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor; The first terminal of the tenth resistor, the first terminal of the eleventh resistor, the first terminal of the sixth capacitor, the non-inverting input terminal of the second operational amplifier, the inverting input terminal of the second operational amplifier, and the input terminal of the second amplifier circuit are all connected together. The second terminal of the tenth resistor is grounded. The second terminal of the eleventh resistor, the second terminal of the sixth capacitor, the output terminal of the second operational amplifier, the first terminal of the twelfth resistor, and the first terminal of the thirteenth resistor are all connected together. The second terminal of the twelfth resistor is grounded. The second terminal of the thirteenth resistor, the first terminal of the fourteenth resistor, the first terminal of the fifteenth resistor, and the first terminal of the seventh capacitor are all connected together. The second terminal of the fourteenth resistor is connected to the first output terminal of the second amplifier circuit. The second terminal of the fifteenth resistor is connected to the second output terminal of the second amplifier circuit. The second terminal of the seventh capacitor is grounded.
[0013] Optionally, the signal switching circuit includes a third operational amplifier, a fourth operational amplifier, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, an eighth capacitor, a ninth capacitor, a third diode, and a fourth diode; The non-inverting input terminal of the third operational amplifier is connected to the first output terminal of the second amplifier circuit. The inverting input terminal, the output terminal, the first terminal of the sixteenth resistor, and the first terminal of the seventeenth resistor are all connected together. The second terminal of the sixteenth resistor is grounded. The second terminal of the seventeenth resistor, the first terminal of the eighth capacitor, and the anode of the third diode are all connected together. The second terminal of the eighth capacitor is grounded. The cathode of the third diode, the cathode of the fourth diode, and the output terminal of the signal switching circuit are all connected together. The inverting input terminal of the fourth operational amplifier, the second output terminal of the second amplifier circuit, and the first terminal of the eighteenth resistor are all connected together. The non-inverting input terminal of the fourth operational amplifier is connected to the first terminal of the nineteenth resistor. The second terminal of the nineteenth resistor is grounded. The second terminal of the eighteenth resistor, the output terminal of the fourth operational amplifier, the first terminal of the twentieth resistor, and the first terminal of the twenty-first resistor are all connected together. The second terminal of the twentieth resistor is grounded. The second terminal of the twenty-first resistor, the first terminal of the ninth capacitor, and the anode of the fourth diode are all connected together. The second terminal of the ninth capacitor is grounded.
[0014] Optionally, the circuit further includes a signal processing circuit connected between the signal inversion circuit and the processor. The signal processing circuit includes a 22nd resistor, a 23rd resistor, a 10th capacitor, a 5th diode, and a 6th diode. The first end of the 22nd resistor is connected to the output terminal of the signal inversion circuit. The second end of the 22nd resistor, the first end of the 10th capacitor, the first end of the 23rd resistor, the cathode of the 5th diode, the anode of the 6th diode, and the output terminal of the signal processing circuit are all connected together. The second end of the 10th capacitor is grounded, the second end of the 23rd resistor is grounded, the anode of the 5th diode is grounded, and the cathode of the 6th diode is connected to a power supply.
[0015] The leakage current detection circuit provided in this application has the following beneficial effects: The leakage current detection circuit provided in this application embodiment includes a leakage current detection ring, a sampling circuit, a protection circuit, a first filter circuit, a first amplification circuit, a second filter circuit, a second amplification circuit, a signal switching circuit, and a processor connected in sequence. The system includes: a leakage current detection ring connected to a leakage current transformer, configured to acquire the residual current of the leakage current transformer; a sampling circuit configured to convert the residual current into a first voltage signal; a protection circuit configured to provide high-voltage protection for the leakage current detection circuit; a first filtering circuit configured to filter high-frequency interference signals in the first voltage signal and perform current limiting processing on the current signal corresponding to the first voltage signal to obtain and output a second voltage signal; a first amplification circuit configured to amplify the second voltage signal to obtain and output a third voltage signal within a first preset voltage range; a second filtering circuit configured to filter operational amplifier noise and high-frequency interference signals in the third voltage signal to obtain and output a fourth voltage signal; a second amplification circuit configured to amplify the fourth voltage signal to obtain and output a fifth voltage signal within a second preset voltage range; a signal flipping circuit configured to flip the negative half-cycle signal in the fifth voltage signal to obtain and output a sixth voltage signal; and a processor configured to determine whether leakage has occurred based on the sixth voltage signal. The signal inversion circuit in the leakage current detection circuit of this application can invert the negative half-cycle signal in the voltage signal to obtain the positive half-cycle signal that the processor can recognize, thereby reducing the protection time of the leakage current detection circuit and improving the safety of the charging pile. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 A schematic diagram of a voltage signal provided in an embodiment of this application; Figure 2 This is a schematic diagram of a leakage current detection circuit provided in an embodiment of this application; Figure 3 A schematic diagram of a voltage signal provided for another embodiment of this application; Figure 4 A schematic diagram of a leakage current detection circuit provided in another embodiment of this application; Figure 5 A schematic diagram of a leakage current detection circuit provided in another embodiment of this application; Figure 6 A schematic diagram of a leakage current detection circuit provided in another embodiment of this application; Figure 7 A schematic diagram of a leakage current detection circuit is provided in another embodiment of this application; Figure 8 This is a schematic diagram of a signal processing circuit provided in an embodiment of this application. Detailed Implementation
[0018] It should be noted that the terminology used in the embodiments of this application is only for explaining specific embodiments of this application and is not intended to limit this application. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, "at least one" or "one or more" means one, two or more. 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 one or more of that feature.
[0019] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.
[0020] Currently, the basic principle of leakage current detection is as follows: When the main circuit conductor passes through the iron core, under normal conditions, the current vector sum is zero, there is no change in magnetic flux in the iron core, and the secondary coil has no output signal. When leakage current or electric shock occurs, part of the current flows to the ground through an abnormal path, causing the current vector sum to no longer be zero, that is, the leakage current transformer generates residual current. At this time, the magnetic flux in the iron core changes, and the secondary coil of the leakage current transformer induces a voltage signal proportional to the residual current.
[0021] In the prior art, leakage current detection circuits can usually determine whether leakage current has occurred based on voltage signals. However, the processors in current leakage current detection circuits can usually only identify the positive half-cycle signal in the voltage signal, and it is difficult to identify the negative half-cycle signal in the voltage signal.
[0022] Please see Figure 1 , Figure 1 A schematic diagram of a voltage signal provided in an embodiment of this application is shown below. Figure 1As shown, the voltage signal includes a positive half-cycle signal and a negative half-cycle signal. Since the processor in the current leakage detection circuit can usually only identify the positive half-cycle signal of the voltage signal and has difficulty identifying the negative half-cycle signal, when a leakage occurs in the charging pile, if the voltage signal received by the processor is a negative half-cycle signal, the processor cannot determine that a leakage has occurred in the charging pile based on the voltage signal at the current moment.
[0023] by Figure 1 For example, if the processor receives a voltage signal at time t1, since the voltage signal is in its negative half-cycle from t1 to t2, the processor cannot determine that the charging pile has leaked current during these two times. However, the voltage signal is in its positive half-cycle from t2 to t3, so the processor can only determine that the charging pile has leaked current during these two times. Therefore, because the charging pile has already leaked current before time t1, the processor can only determine that the charging pile has leaked current after time t2. This shows that the protection time of the leakage detection circuit in the existing technology is relatively long, reducing the safety of the charging pile.
[0024] Based on this, this application provides a leakage current detection circuit to solve the technical problem that the long protection time of the leakage current detection circuit in the prior art leads to low safety of the charging pile.
[0025] Please see Figure 2 , Figure 2 This is a schematic diagram of a leakage current detection circuit provided in an embodiment of this application. Figure 2 As shown, the leakage current detection circuit includes a leakage current detection ring 11, a sampling circuit 12, a protection circuit 13, a first filter circuit 14, a first amplifier circuit 15, a second filter circuit 16, a second amplifier circuit 17, a signal switching circuit 18, and a processor 19 connected in sequence.
[0026] The leakage current detection ring 11 is connected to the leakage current transformer and is configured to obtain the residual current of the leakage current transformer.
[0027] The sampling circuit 12 is configured to convert the residual current into a first voltage signal.
[0028] Protection circuit 13 is configured to provide high-voltage protection for the leakage current detection circuit.
[0029] The first filter circuit 14 is configured to filter high-frequency interference signals in the first voltage signal and to perform current limiting processing on the current signal corresponding to the first voltage signal to obtain and output the second voltage signal.
[0030] The first amplifier circuit 15 is configured to amplify the second voltage signal to obtain and output a third voltage signal within a first preset voltage range.
[0031] The second filter circuit 16 is configured to filter operational amplifier noise and high-frequency interference signals of the third voltage signal to obtain and output the fourth voltage signal.
[0032] The second amplifier circuit 17 is configured to amplify the fourth voltage signal to obtain and output a fifth voltage signal within a second preset voltage range.
[0033] The signal flipping circuit 18 is configured to flip the negative half-cycle signal in the fifth voltage signal to obtain and output the sixth voltage signal.
[0034] Processor 19 is configured to determine whether leakage has occurred based on a sixth voltage signal.
[0035] The signal inversion circuit 18 in the leakage current detection circuit of this application can invert the negative half-cycle signal in the voltage signal to obtain the positive half-cycle signal that the processor can recognize. Please refer to... Figure 3 , Figure 3 This is a schematic diagram of a voltage signal provided for another embodiment of this application. Figure 3 The voltage signal shown is the voltage signal after being processed by the signal inversion circuit 18. Figure 3 The voltage signal shown is Figure 1 Compared to the voltage signal shown, Figure 3 The voltage signal shown only includes the positive half-cycle signal.
[0036] by Figure 3 For example, if the processor receives a voltage signal at time t1, after the signal switching circuit 18, the voltage signal at time t1 to time t2 is a positive half-cycle signal. Therefore, the processor can determine that the charging pile has a leakage at time t1 to time t2.
[0037] It can be seen that, through existing technologies, Figure 1 The voltage signal shown indicates that the processor can only determine that the charging pile has leaked current after time t2. However, the leakage detection circuit of this application corresponds to... Figure 3 The voltage signal shown indicates that the processor can determine that the charging pile has leaked current after time t1, thus reducing the protection time and improving the safety of the charging pile.
[0038] Please see Figure 4 , Figure 4 This is a schematic diagram of a leakage current detection circuit provided in another embodiment of this application.
[0039] Figure 4 The leakage current detection circuit shown is a part of the leakage current detection circuit provided in the embodiment of this application, specifically showing the leakage current detection ring 11, sampling circuit 12, protection circuit 13 and first filter circuit 14.
[0040] The leakage current detection ring 11 includes two input ports for acquiring the residual current of the leakage current transformer. In addition, the leakage current detection ring 11 includes a first output terminal and a second output terminal for sending the residual current to the sampling circuit 12 through the first output terminal and the second output terminal.
[0041] The sampling circuit 12 includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 and the first end of the second resistor R2 are connected to ground. The second end of the first resistor R1, the first output end of the leakage current detection ring 11 and the first input end of the protection circuit 13 are connected together. The second end of the second resistor R2, the second output end of the leakage current detection ring 11 and the second input end of the protection circuit 13 are connected together.
[0042] The working principle of the sampling circuit 12 is as follows: the first resistor R1 and the second resistor R2 in the sampling circuit 12 convert the residual current sent by the leakage detection ring 11 into a first voltage signal, and send the first voltage signal to the first filter circuit 14.
[0043] The protection circuit 13 includes a first diode Q1 and a second diode Q2; the cathode of the first diode Q1, the anode of the second diode Q2, the first input terminal of the protection circuit 13 and the first output terminal of the protection circuit 13 are connected together, and the anode of the first diode Q1, the cathode of the second diode Q2, the second input terminal of the protection circuit 13 and the second output terminal of the protection circuit 13 are connected together.
[0044] The working principle of the protection circuit 13 is as follows: When a positive instantaneous high voltage (high potential relative to GND) appears at the output terminal of the sampling circuit 12, the device composed of the first diode Q1 and the second diode Q2 is in a "reverse bias" state; when the high voltage exceeds the reverse breakdown voltage of the device composed of the first diode Q1 and the second diode Q2, the device composed of the first diode Q1 and the second diode Q2 conducts in reverse, "clamping" the voltage at the output terminal of the sampling circuit 12 at the reverse breakdown voltage value of the device composed of the first diode Q1 and the second diode Q2, preventing the high voltage from continuing to be transmitted to the subsequent stage. When the instantaneous high voltage disappears, the device composed of the first diode Q1 and the second diode Q2 returns to the reverse cutoff state, which does not affect the transmission of the normal leakage signal. The voltage amplitude of the normal leakage signal is much lower than the reverse breakdown voltage of the device composed of the first diode Q1 and the second diode Q2. The device composed of the first diode Q1 and the second diode Q2 is always in the cutoff state and will not cause attenuation or distortion to the useful signal.
[0045] The first filter circuit 14 includes a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, and a third capacitor C3. The first end of the third resistor R1 is connected to the first output terminal of the protection circuit 13. The second end of the third resistor R3, the first end of the first capacitor C1, the first end of the second capacitor C2, and the first output terminal of the first filter circuit 14 are all connected together. The first end of the fourth resistor R4 is connected to the second output terminal of the protection circuit 13. The second end of the fourth resistor R4, the second end of the first capacitor C1, the first end of the third capacitor C3, and the second output terminal of the first filter circuit 14 are all connected together. The second end of the second capacitor C2 and the second end of the third capacitor C3 are all connected to ground.
[0046] The working principle of the first filter circuit 14 is as follows: the current signal corresponding to the first voltage signal is current-limited through the third resistor R3 and the fourth resistor R4, and the high-frequency interference signal in the first voltage signal is filtered through the first capacitor C1, the second capacitor C2 and the third capacitor C3 to obtain the second voltage signal, and the second voltage signal is output to the first amplifier circuit 15.
[0047] Please see Figure 5 , Figure 5 This is a schematic diagram of a leakage current detection circuit provided in another embodiment of this application.
[0048] Figure 5 The leakage current detection circuit shown is a part of the leakage current detection circuit provided in the embodiment of this application, specifically showing the first amplification circuit 15 and the second filter circuit 16.
[0049] The first amplifier circuit 15 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a first operational amplifier U1. The first end of the fifth resistor R5 is connected to the first output terminal of the first filter circuit 14. The second end of the fifth resistor R5, the first end of the sixth resistor R6, and the inverting input terminal of the first operational amplifier U1 are connected together. The second end of the sixth resistor R6, the output terminal of the first operational amplifier U1, and the output terminal of the first amplifier circuit 15 are connected together. The first end of the seventh resistor R7 is connected to the second output terminal of the first filter circuit 14. The second end of the seventh resistor R7, the first end of the eighth resistor R8, and the non-inverting input terminal of the first operational amplifier U1 are connected together. The second end of the eighth resistor R8 is grounded.
[0050] The first amplifier circuit 15 works as follows: it receives the weak leakage voltage signal output from the first filter circuit 14 and connects it to the inverting input of the first operational amplifier U1 through the sixth resistor R6. The non-inverting input of the first operational amplifier U1 is grounded through the eighth resistor R8, thus ensuring that the operational amplifier U1 operates in the linear region. This amplifies the second voltage signal to obtain a third voltage signal within the first preset voltage range, and then sends the third voltage signal to the second filter circuit 16. This enhances the signal's anti-interference capability and prevents excessive noise amplification, laying the foundation for subsequent in-depth processing.
[0051] The second filter circuit 16 includes a ninth resistor R9, a fourth capacitor C4, and a fifth capacitor C5. The first end of the fourth capacitor C4 is connected to the output end of the first amplifier circuit 15. The second end of the fourth capacitor C4, the first end of the ninth resistor R9, the first end of the fifth capacitor C5, and the output end of the second filter circuit 16 are all connected together. The second end of the ninth resistor R9 and the second end of the fifth capacitor C5 are all connected to ground.
[0052] The working principle of the second filter circuit 16 is as follows: the fourth capacitor C4 is connected in parallel between the signal terminal and GND. Based on the capacitor's "high frequency low impedance, low frequency high impedance" characteristics, residual high frequency interference (such as power grid harmonics and operational amplifier noise) is grounded through the capacitor, while the leakage signal is retained, further reducing noise interference. In addition, the fifth capacitor C5 is in the feedback loop of the second amplifier circuit 17, which can cancel the inherent phase delay of the operational amplifier, reduce the high frequency gain, and avoid self-oscillation when the second amplifier circuit 17 amplifies at high gain.
[0053] Please see Figure 6 , Figure 6 This is a schematic diagram of a leakage current detection circuit provided in another embodiment of this application.
[0054] Figure 6 The leakage current detection circuit shown is a part of the leakage current detection circuit provided in the embodiments of this application, specifically showing the second amplification circuit 17 and the signal inversion circuit 18.
[0055] The second amplifier circuit 17 includes a sixth capacitor C6, a seventh capacitor C7, a second operational amplifier U2, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, and a fifteenth resistor R15. The first terminal of the tenth resistor R10, the first terminal of the eleventh resistor R11, the first terminal of the sixth capacitor C6, the non-inverting input terminal of the second operational amplifier U2, the inverting input terminal of the second operational amplifier U2, and the input terminal of the second amplifier circuit 17 are all connected together. The second terminal of the tenth resistor R10 is grounded. The second terminal of the eleventh resistor R11, the second terminal of the sixth capacitor C6, the output terminal of the second operational amplifier U2, the first terminal of the twelfth resistor R12, and the first terminal of the thirteenth resistor R13 are all connected together. The second terminal of the twelfth resistor R12 is grounded. The second terminal of the thirteenth resistor R13, the first terminal of the fourteenth resistor R14, the first terminal of the fifteenth resistor R15, and the first terminal of the seventh capacitor C7 are all connected together. The second terminal of the fourteenth resistor R14 is connected to the first output terminal of the second amplifier circuit 17. The second terminal of the fifteenth resistor R15 is connected to the second output terminal of the second amplifier circuit 17. The second terminal of the seventh capacitor C7 is grounded.
[0056] The working principle of the second amplifier circuit 17 is as follows: by utilizing the "virtual short" and "virtual open" characteristics of the operational amplifier, the eleventh resistor R11 and the tenth resistor R10 form an amplification network, and the fourth voltage signal output by the second filter circuit 16 is further amplified by the second operational amplifier U2 to obtain the fifth voltage signal within the second preset voltage range, and the fifth voltage signal is output to the signal inversion circuit 18.
[0057] The signal switching circuit 18 includes a third operational amplifier U3, a fourth operational amplifier U4, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, an eighth capacitor C8, a ninth capacitor C9, a third diode Q3, and a fourth diode Q4.
[0058] The non-inverting input of the third operational amplifier U3 is connected to the first output of the second amplifier circuit 17. The inverting input, output, first terminals of the sixteenth and seventeenth resistors R16 and R17 are connected together. The second terminal of the sixteenth resistor R16 is grounded. The second terminal of the seventeenth resistor, the first terminal of the eighth capacitor C8, and the anode of the third diode Q3 are connected together. The second terminal of the eighth capacitor C8 is grounded. The cathodes of the third and fourth diodes Q4 and the output of the signal switching circuit 18 are connected together. The fourth operational amplifier U4... The inverting input terminal, the second output terminal of the second amplifier circuit 17, and the first terminal of the eighteenth resistor R18 are connected together. The non-inverting input terminal of the fourth operational amplifier U4 is connected to the first terminal of the nineteenth resistor R19. The second terminal of the nineteenth resistor R19 is grounded. The second terminal of the eighteenth resistor R18, the output terminal of the fourth operational amplifier U4, the first terminal of the twentieth resistor R20, and the first terminal of the twenty-first resistor R21 are connected together. The second terminal of the twentieth resistor R20 is grounded. The second terminal of the twenty-first resistor R21, the first terminal of the ninth capacitor C9, and the anode of the fourth diode Q4 are connected together. The second terminal of the ninth capacitor C9 is grounded.
[0059] The working principle of the signal switching circuit 18 is as follows: when the fifth voltage signal is a positive half-cycle signal, the fifth voltage signal is processed by the third operational amplifier U3 and output through the third diode Q3; when the fifth voltage signal is a negative half-cycle signal, the fifth voltage signal is switched by the fourth operational amplifier U3 and output through the fourth diode Q4.
[0060] In one possible implementation, the leakage current detection circuit may further include a signal processing circuit 20. The signal processing circuit 20 may be connected between the signal switching circuit 18 and the processor 19. The leakage current detection circuit may also include a self-test circuit 21, which may be connected to both the processor 19 and the leakage current transformer.
[0061] Please see Figure 7 , Figure 7 This application also provides a schematic diagram of a leakage current detection circuit according to another embodiment.
[0062] The signal processing circuit 20 is configured to perform level conversion, filtering and protection processing on the sixth voltage signal output by the signal inversion circuit 18 to ensure that the sixth voltage signal output by the signal inversion circuit 18 can meet the requirements of the processor 19.
[0063] Please see Figure 8 , Figure 8 This is a schematic diagram of a signal processing circuit provided in an embodiment of this application.
[0064] The signal processing circuit 20 includes a 22nd resistor R22, a 23rd resistor R23, a 10th capacitor C10, a 5th diode Q5, and a 6th diode Q6. The first end of the 22nd resistor R22 is connected to the output of the signal switching circuit 18. The second end of the 22nd resistor R22, the first end of the 10th capacitor C10, the first end of the 23rd resistor R23, the cathode of the 5th diode Q5, the anode of the 6th diode Q6, and the output of the signal processing circuit 18 are all connected together. The second end of the 10th capacitor C10 is grounded, the second end of the 23rd resistor R23 is grounded, the anode of the 5th diode Q5 is grounded, and the cathode of the 6th diode Q6 is connected to the power supply.
[0065] The signal processing circuit 20 operates as follows: Diodes Q5 (fifth) and Q6 (sixth) can be bidirectional Zener diodes (or transient voltage suppressor diodes), connected in parallel between the power supply (VCC) and ground. This clamps voltage fluctuations at the output of the signal processing circuit 20, preventing overvoltage damage to subsequent circuits and suppressing power supply noise. Resistor R23 (twenty-third) and capacitor C10 (tenth) form an RC filter network to filter out high-frequency interference in the input signal, making the signal smoother. Resistor R22 (twenty-second) is a current-limiting resistor, controlling the current amplitude corresponding to the sixth voltage signal input to the signal processing circuit 20, ensuring the circuit operates within a safe range. Finally, the processed signal is output from the output of the signal processing circuit 20 for acquisition or control by the processor 19.
[0066] The self-test circuit 21 is configured to, upon receiving a leakage current simulation command from the processor, control the leakage current transformer to generate a simulated residual current, thereby testing other circuits included in the leakage current detection circuit. Furthermore, the processor 19 is also configured to determine whether the leakage current detection circuit is functioning correctly based on a sixth voltage signal.
[0067] As can be seen from the above, the leakage current detection circuit provided in this application embodiment includes a leakage current detection ring, a sampling circuit, a protection circuit, a first filter circuit, a first amplification circuit, a second filter circuit, a second amplification circuit, a signal switching circuit, and a processor connected in sequence. The system includes: a leakage current detection ring connected to a leakage current transformer, configured to acquire the residual current of the leakage current transformer; a sampling circuit configured to convert the residual current into a first voltage signal; a protection circuit configured to provide high-voltage protection for the leakage current detection circuit; a first filtering circuit configured to filter high-frequency interference signals in the first voltage signal and perform current limiting processing on the current signal corresponding to the first voltage signal to obtain and output a second voltage signal; a first amplification circuit configured to amplify the second voltage signal to obtain and output a third voltage signal within a first preset voltage range; a second filtering circuit configured to filter operational amplifier noise and high-frequency interference signals in the third voltage signal to obtain and output a fourth voltage signal; a second amplification circuit configured to amplify the fourth voltage signal to obtain and output a fifth voltage signal within a second preset voltage range; a signal flipping circuit configured to flip the negative half-cycle signal in the fifth voltage signal to obtain and output a sixth voltage signal; and a processor configured to determine whether leakage has occurred based on the sixth voltage signal. The signal inversion circuit in the leakage current detection circuit of this application can invert the negative half-cycle signal in the voltage signal to obtain the positive half-cycle signal that the processor can recognize, thereby reducing the protection time of the leakage current detection circuit and improving the safety of the charging pile.
[0068] Those skilled in the art will understand that, for the sake of convenience and brevity, the above-described division of functional circuits is merely an example. In practical applications, the functions described above can be assigned to different functional circuits as needed, that is, the internal structure of the leakage current detection circuit can be divided into different functional circuits to complete all or part of the functions described above. The functional circuits in the embodiments can be integrated into one processing circuit, or each circuit can exist physically separately, or two or more circuits can be integrated into one circuit. The integrated circuit can be implemented in hardware or software. Furthermore, the specific names of the functional circuits are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the circuits in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0069] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the steps in the various method embodiments described above.
[0070] This application provides a computer program product that, when run on a terminal device, enables the terminal device to implement the steps described in the various method embodiments above.
[0071] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.
[0072] Those skilled in the art will recognize that the circuit and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0073] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.
Claims
1. A leakage current detection circuit, characterized in that, It includes a leakage current detection ring, a sampling circuit, a protection circuit, a first filter circuit, a first amplification circuit, a second filter circuit, a second amplification circuit, a signal switching circuit, and a processor connected in sequence; The leakage current detection ring is connected to the leakage current transformer and is configured to obtain the residual current of the leakage current transformer; The sampling circuit is configured to convert the residual current into a first voltage signal; The protection circuit is configured to provide high-voltage protection for the leakage current detection circuit; The first filtering circuit is configured to filter high-frequency interference signals in the first voltage signal and to perform current limiting processing on the current signal corresponding to the first voltage signal to obtain and output the second voltage signal. The first amplifier circuit is configured to amplify the second voltage signal to obtain and output a third voltage signal within a first preset voltage range; The second filter circuit is configured to filter operational amplifier noise and high-frequency interference signals from the third voltage signal to obtain and output a fourth voltage signal; The second amplifier circuit is configured to amplify the fourth voltage signal to obtain and output a fifth voltage signal within a second preset voltage range; The signal flipping circuit is configured to flip the negative half-cycle signal in the fifth voltage signal to obtain and output the sixth voltage signal. The processor is configured to determine whether leakage has occurred based on the sixth voltage signal.
2. The circuit according to claim 1, characterized in that, The circuit also includes a self-test circuit; the self-test circuit is connected to the processor and the leakage current transformer respectively. The self-test circuit is configured to control the leakage current transformer to generate a simulated residual current after receiving a leakage current simulation command sent by the processor.
3. The circuit according to claim 1, characterized in that, The sampling circuit includes a first resistor and a second resistor. The first end of the first resistor and the first end of the second resistor are both connected to ground. The second end of the first resistor, the first output end of the leakage current detection ring, and the first input end of the protection circuit are all connected together. The second end of the second resistor, the second output end of the leakage current detection ring, and the second input end of the protection circuit are all connected together.
4. The circuit according to claim 1, characterized in that, The protection circuit includes a first diode and a second diode; the cathode of the first diode, the anode of the second diode, the first input terminal of the protection circuit, and the first output terminal of the protection circuit are all connected together, and the anode of the first diode, the cathode of the second diode, the second input terminal of the protection circuit, and the second output terminal of the protection circuit are all connected together.
5. The circuit according to claim 1, characterized in that, The first filter circuit includes a third resistor, a fourth resistor, a first capacitor, a second capacitor, and a third capacitor; the first end of the third resistor is connected to the first output terminal of the protection circuit, the second end of the third resistor, the first end of the first capacitor, the first end of the second capacitor, and the first output terminal of the first filter circuit are all connected together, the first end of the fourth resistor is connected to the second output terminal of the protection circuit, the second end of the fourth resistor, the second end of the first capacitor, the first end of the third capacitor, and the second output terminal of the first filter circuit are all connected together, and the second end of the second capacitor and the second end of the third capacitor are all connected to ground.
6. The circuit according to claim 1, characterized in that, The first amplification circuit includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a first operational amplifier; the first end of the fifth resistor is connected to the first output terminal of the first filter circuit, the second end of the fifth resistor, the first end of the sixth resistor, and the inverting input terminal of the first operational amplifier are all connected together, the second end of the sixth resistor, the output terminal of the first operational amplifier, and the output terminal of the first amplification circuit are all connected together, the first end of the seventh resistor is connected to the second output terminal of the first filter circuit, the second end of the seventh resistor, the first end of the eighth resistor, and the non-inverting input terminal of the first operational amplifier are all connected together, and the second end of the eighth resistor is grounded.
7. The circuit according to claim 1, characterized in that, The second filter circuit includes a ninth resistor, a fourth capacitor, and a fifth capacitor; the first terminal of the fourth capacitor is connected to the output terminal of the first amplifier circuit, and the second terminal of the fourth capacitor, the first terminal of the ninth resistor, the first terminal of the fifth capacitor, and the output terminal of the second filter circuit are all connected together, and the second terminal of the ninth resistor and the second terminal of the fifth capacitor are all connected to ground.
8. The circuit according to claim 1, characterized in that, The second amplifier circuit includes a sixth capacitor, a seventh capacitor, a second operational amplifier, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, and a fifteenth resistor; The first terminal of the tenth resistor, the first terminal of the eleventh resistor, the first terminal of the sixth capacitor, the non-inverting input terminal of the second operational amplifier, the inverting input terminal of the second operational amplifier, and the input terminal of the second amplifier circuit are all connected together. The second terminal of the tenth resistor is grounded. The second terminal of the eleventh resistor, the second terminal of the sixth capacitor, the output terminal of the second operational amplifier, the first terminal of the twelfth resistor, and the first terminal of the thirteenth resistor are all connected together. The second terminal of the twelfth resistor is grounded. The second terminal of the thirteenth resistor, the first terminal of the fourteenth resistor, the first terminal of the fifteenth resistor, and the first terminal of the seventh capacitor are all connected together. The second terminal of the fourteenth resistor is connected to the first output terminal of the second amplifier circuit. The second terminal of the fifteenth resistor is connected to the second output terminal of the second amplifier circuit. The second terminal of the seventh capacitor is grounded.
9. The circuit according to claim 1, characterized in that, The signal switching circuit includes a third operational amplifier, a fourth operational amplifier, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, an eighth capacitor, a ninth capacitor, a third diode, and a fourth diode; The non-inverting input terminal of the third operational amplifier is connected to the first output terminal of the second amplifier circuit. The inverting input terminal, the output terminal, the first terminal of the sixteenth resistor, and the first terminal of the seventeenth resistor are all connected together. The second terminal of the sixteenth resistor is grounded. The second terminal of the seventeenth resistor, the first terminal of the eighth capacitor, and the anode of the third diode are all connected together. The second terminal of the eighth capacitor is grounded. The cathode of the third diode, the cathode of the fourth diode, and the output terminal of the signal switching circuit are all connected together. The inverting input terminal of the fourth operational amplifier, the second output terminal of the second amplifier circuit, and the first terminal of the eighteenth resistor are all connected together. The non-inverting input terminal of the fourth operational amplifier is connected to the first terminal of the nineteenth resistor. The second terminal of the nineteenth resistor is grounded. The second terminal of the eighteenth resistor, the output terminal of the fourth operational amplifier, the first terminal of the twentieth resistor, and the first terminal of the twenty-first resistor are all connected together. The second terminal of the twentieth resistor is grounded. The second terminal of the twenty-first resistor, the first terminal of the ninth capacitor, and the anode of the fourth diode are all connected together. The second terminal of the ninth capacitor is grounded.
10. The circuit according to claim 1, characterized in that, The circuit further includes a signal processing circuit connected between the signal inversion circuit and the processor. The signal processing circuit includes a 22nd resistor, a 23rd resistor, a 10th capacitor, a 5th diode, and a 6th diode. The first end of the 22nd resistor is connected to the output end of the signal inversion circuit. The second end of the 22nd resistor, the first end of the 10th capacitor, the first end of the 23rd resistor, the cathode of the 5th diode, the anode of the 6th diode, and the output end of the signal processing circuit are all connected together. The second end of the 10th capacitor is grounded, the second end of the 23rd resistor is grounded, the anode of the 5th diode is grounded, and the cathode of the 6th diode is connected to the power supply.