Electric leakage detection circuit and electric leakage detection device

Abstract

The application discloses an electric leakage detection circuit and an electric leakage detection device. The electric leakage detection circuit comprises a gun seat, a sampling module, an electric leakage generation module and a control module. When the gun head of the alternating current charging pile is connected through the gun seat, the sampling module detects the alternating current voltage of the gun seat, the electric leakage generation module simulates the electric leakage of the alternating current charging pile and simulates the plug-pull action according to the electric leakage generation signal, the control module generates the electric leakage generation signal according to the electric leakage test instruction, and the difference between the electric leakage reaction time and the electric leakage generation time of the electric leakage generation module is used to determine the electric leakage action time of the alternating current charging pile. The electric leakage detection process is highly automated based on a simple structure, the electric leakage detection difficulty is reduced, the electric leakage detection process is simplified on the basis of high automation, and the time cost of the electric leakage detection is reduced.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a leakage current detection circuit and a leakage current detection device. Background Technology

[0002] With the development of new energy vehicles, the growth rate of charging piles has accelerated. Charging piles are prone to leakage, especially after mass production. Leakage detection failure or delayed leakage response may lead to serious consequences that could endanger personal safety.

[0003] However, detecting the leakage current action time of charging piles is difficult and time-consuming. Summary of the Invention

[0004] This application provides a leakage current detection circuit and a leakage current detection device to alleviate the technical problem that the detection of leakage current action time of charging piles is difficult and time-consuming.

[0005] In a first aspect, this application provides a leakage current detection circuit, which includes a gun holder, a sampling module, a leakage current generation module, and a control module. The gun holder is used to connect to the charging head of an AC charging pile; the sampling module is connected to the gun holder and is used to detect the AC voltage of the gun holder; the leakage current generation module is connected to the gun holder and is used to simulate the leakage current of the AC charging pile and simulate the plugging and unplugging action based on the leakage current generation signal; the control module is connected to the sampling module and the leakage current generation module and is used to generate a leakage current generation signal according to the leakage current test command, and determine the leakage current action time of the AC charging pile based on the difference between the leakage current response time and the leakage current generation time of the leakage current generation module.

[0006] Optionally, the control module is used to determine the leakage current response time based on the difference between the generation time of the effective level of the leakage current generation signal and the power-off time of the AC voltage of the gun holder.

[0007] Optionally, when the AC charging pile is powered by three-phase electricity, the gun holder includes a first live wire, a second live wire, a third live wire, a neutral wire, a ground wire, and a control lead wire; when the AC charging pile is powered by split-phase electricity, the gun holder includes a first live wire, a multi-function wire, a ground wire, and a control lead wire, wherein the multi-function wire is configured as either a neutral wire or a second live wire.

[0008] Optionally, the sampling module is connected to the first live wire, the second live wire, the third live wire, the multi-function wire, and the control module to sample the phase voltage or line voltage of the gun holder to generate the corresponding sampling voltage and transmit the sampling voltage to the control module.

[0009] Optionally, the leakage current generation module includes a switching unit and a driving unit. The switching unit is connected to the first live wire, the second live wire, the third live wire, the ground wire, and the control lead wire. The switching unit is used to control the connection status between at least one of the first live wire, the second live wire, the third live wire, and the control lead wire and the ground wire. The driving unit is connected to the switching unit and the control module. The driving unit is used to supply power to the control module and drive the switching unit according to the leakage current generation signal.

[0010] Optionally, the switching unit includes a first relay, a first resistor, a second relay, and a second resistor. The first relay includes a first contact and a first coil. The first contact is connected between a first live wire and a ground wire. The first coil is connected to a drive unit, which is configured to control the power supply of the first coil. The first resistor is connected in series with the first contact. The second relay includes a second contact and a second coil. The second contact is connected between a control lead and a ground wire. The second coil is connected to the drive unit, which is configured to control the power supply of the second coil. The second resistor is connected in series with the second contact.

[0011] Optionally, the switching unit further includes a third relay, a third resistor, a fourth relay, and a fourth resistor. The third relay includes a third contact and a third coil. The third contact is connected between the second live wire and the ground wire. The third coil is connected to a drive unit, which is configured to control the power supply of the third coil. The third resistor is connected in series with the third contact. The fourth relay includes a fourth contact and a fourth coil. The fourth contact is connected between the third live wire and the ground wire. The fourth coil is connected to a drive unit, which is configured to control the power supply of the fourth coil. The fourth resistor is connected in series with the fourth contact.

[0012] Optionally, when the AC voltage of the gun holder is the line voltage, the control module is used to determine the leakage response time based on at least one data acquisition block of the line voltage.

[0013] Optionally, the control module obtains the maximum difference and the sampling distance corresponding to the maximum difference in a data block based on the filter pointer. When the maximum difference and the sampling distance both meet the corresponding conditions, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period. The position difference corresponding to the filter pointer is the position of the current position of the filter pointer and the position corresponding to the starting data in the data block.

[0014] Optionally, in the control module, the data acquisition block includes multiple data acquisitions, the filter pointer points to the starting data of a data acquisition block, the maximum difference between the maximum and minimum data acquisitions among the multiple data acquisitions is calculated, and the sampling distance between the position of the maximum data acquisition and the position of the minimum data acquisition is calculated; when the maximum difference is less than a first preset value and the sampling distance is greater than a second preset value, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period.

[0015] Optionally, when the average of multiple collected data is outside the zero-crossing interval, the second preset value is the first value; when the average of multiple collected data is within the zero-crossing interval, the second preset value is the second value; the first value is greater than the second value.

[0016] Secondly, this application also provides a leakage current detection device, which includes the leakage current detection circuit described above.

[0017] Optionally, the leakage current detection device also includes a host computer, which is connected to the control module. The host computer is configured to send leakage current test commands and read back the leakage current action time, and determine whether the AC charging pile meets the leakage current protection requirements based on the leakage current action time.

[0018] The leakage current detection circuit and device provided in this application, when connected to the charging head of an AC charging pile via a gun holder, the sampling module detects the AC voltage of the gun holder, the leakage current generation module simulates the leakage current of the AC charging pile and simulates the plugging and unplugging action based on the leakage current generation signal, and the control module generates a leakage current generation signal based on the leakage current test command, and determines the leakage current action time of the AC charging pile based on the difference between the leakage current response time and the leakage current generation time of the leakage current generation module. This not only achieves a highly automated leakage current detection process based on a simple structure, reducing the difficulty of leakage current detection, but also simplifies the leakage current detection process on the basis of high automation, thereby reducing the time spent on leakage current detection. Attached Figure Description

[0019] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the leakage current detection circuit provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the first structure of the gun mount provided in an embodiment of this application.

[0022] Figure 3 This is a schematic diagram of a second structure of the gun mount provided in an embodiment of this application.

[0023] Figure 4 The circuit diagram is shown for the leakage current detection circuit provided in the embodiment of this application.

[0024] Figure 5 This is a schematic diagram of a first type of leakage current detection circuit provided in an embodiment of this application.

[0025] Figure 6 This is a first schematic diagram of a charging pile experiencing a power outage, as provided in an embodiment of this application.

[0026] Figure 7This is a second schematic diagram of a charging pile experiencing a power outage, as provided in an embodiment of this application.

[0027] Figure 8 This is a third schematic diagram of a charging pile experiencing a power outage, as provided in an embodiment of this application.

[0028] Figure 9 This is a second flowchart illustrating the leakage current detection circuit provided in an embodiment of this application.

[0029] Figure 10 This is a schematic diagram of the first structure of the leakage current detection device provided in the embodiments of this application.

[0030] Figure 11 This is a schematic diagram of a second structure of the leakage current detection device provided in the embodiments of this application. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] 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 technical features indicated. Features thus defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0033] With the development of new energy vehicles, the growth rate of charging piles has accelerated, and safety has also become a concern. Among the key technologies related to personal safety are leakage detection and leakage response time. The leakage response time is the difference between the time it takes for leakage to occur and the time it takes for the charging pile (pile body) to respond, as observed by an oscilloscope in the laboratory.

[0034] Especially after mass production, if leakage current detection fails or the leakage current action is not timely, it may lead to serious consequences that could cause personal injury. The main reasons for this are as follows:

[0035] 1. During the safety certification of charging piles, the inspection is mainly carried out on individual samples. After mass production, individual inspections are no longer carried out. As a result, some charging piles may be defective products with untimely leakage response and enter the market.

[0036] 2. After mass production, it is difficult and time-consuming to test the leakage current action time of individual charging piles. Using a sampling inspection method may also lead to missed detections.

[0037] 3. If a specialized leakage current detection device is used to obtain the leakage current action time, the price of such device is relatively expensive and the size is also relatively large.

[0038] This application determines whether the time from leakage to power cut-off of the charging pile is within safety standards by detecting the time it takes for the charging pile to disconnect the power, thereby determining whether the charging pile meets safety regulations. It can also improve the automation level of mass production. Equipped with gun bases of different standards, it can adapt to leakage detection of charging piles of different standards. Internally, it can control the switching of different phase grounding and the guidance control (CP), realizing one-click acquisition of the leakage action time of the charging pile, which is convenient for mass production. It is also small in size and highly practical.

[0039] like Figure 1 As shown, this embodiment provides a leakage current detection circuit 100, which includes a gun holder 10, a sampling module 20, a leakage current generation module 30, and a control module 40. The gun holder 10 is used to connect to the gun head 210 of the AC charging pile 200; the sampling module 20 is connected to the gun holder 10 and is used to detect the AC voltage of the gun holder 10; the leakage current generation module 30 is connected to the gun holder 10 and is used to simulate the leakage current of the AC charging pile 200 and simulate the plugging and unplugging action according to the leakage current generation signal; the control module 40 is connected to the sampling module 20 and the leakage current generation module 30, and is used to generate a leakage current generation signal according to the leakage current test command, and determine the leakage current action time of the AC charging pile 200 according to the difference between the leakage current response time and the leakage current generation time of the leakage current generation module 30.

[0040] It is understood that when the leakage detection circuit 100 provided in this embodiment is connected to the gun head 210 of the AC charging pile 200 through the gun holder 10, the sampling module 20 detects the AC voltage of the gun holder 10, the leakage generation module 30 simulates the leakage of the AC charging pile 200 and simulates the plugging and unplugging action according to the leakage generation signal, and the control module 40 generates the leakage generation signal according to the leakage test command, and determines the leakage action time of the AC charging pile 200 according to the difference between the leakage reaction time and the leakage generation time of the leakage generation module 30. It not only realizes a highly automated leakage detection process based on a simple structure, reducing the difficulty of leakage detection, but also simplifies the leakage detection process on the basis of high automation, thereby reducing the time spent on leakage detection.

[0041] It should be noted that, due to the relatively simple structure of the leakage current detection circuit 100, its size can be reduced, making it easy to move or carry, and it can be used for leakage current detection in laboratories or mass production workshops. The sampling module 20 can sample data from an analog-to-digital converter (ADC), or it can convert the data into voltage and then perform filtering calculations. The control module 40 can be a motherboard including a microcontroller unit (MCU), or it can be other control chips such as a digital signal processor (DSP) or a programmable logic controller (PLC).

[0042] In some embodiments, the control module 40 is used to determine the leakage current response time based on the difference between the generation time of the effective level of the leakage current generation signal and the power-off time of the AC voltage of the gun holder 10.

[0043] It should be noted that leakage response time refers to the time from the occurrence of leakage to the drop in the charging pile's output voltage to the threshold voltage. The time it takes for the effective level of the leakage signal to be generated is the leakage occurrence time.

[0044] In some embodiments, such as Figure 2 As shown, when the AC charging pile 200 is powered by three-phase electricity, the charging gun base 10 includes a first live wire L1, a second live wire L2, a third live wire L3, a neutral wire N, a ground wire PE, and a control lead wire CP. Figure 3 As shown, when the AC charging pile 200 is powered by split-phase electricity, the gun holder 10 includes a first live wire L1, a multi-function wire L2 / N, a ground wire PE, and a control guide wire CP. The multi-function wire L2 / N is configured as a neutral wire N or a second live wire L2.

[0045] It should be noted that, for Figure 2 Specifically, the gun holder 10 includes a first live wire L1, a second live wire L2, a third live wire L3, a ground wire PE, and a control guide wire CP. This gun holder 10 is suitable for three-phase AC charging piles conforming to national standards and European standards. Figure 3 Specifically, the gun holder 10 includes a first live wire L1, a multi-function wire L2 / N, a ground wire PE, and a control guide wire CP. The multi-function wire L2 / N is configured as either the neutral wire N or the second live wire L2. This gun holder 10 can be used with split-phase AC piles such as those conforming to American standards. Therefore, Figure 4 The gun holder 10 shown can be used for leakage detection of gun heads 210 according to national standards, American standards, European standards, NACS, etc.

[0046] In some embodiments, such as Figure 4 As shown, the sampling module 20 is connected to the first live wire L1, the second live wire L2, the third live wire L3, the multi-function line L2 / N, and the control module 40. It is used to sample the phase voltage or line voltage of the gun holder 10 to generate the corresponding sampling voltage and transmit the sampling voltage to the control module 40.

[0047] It should be noted that the control module 40 can determine whether the output voltage of the charging pile has dropped to the threshold voltage based on the received sampled voltage, thereby determining the leakage current response time. PA1 is the sampling pin for receiving the sampled voltage.

[0048] In some embodiments, such as Figure 4 As shown, the leakage current generation module 30 includes a switching unit 31 and a driving unit 32. The switching unit 31 is connected to the first live wire L1, the second live wire L2, the third live wire L3, the ground wire PE, and the control lead wire CP. The switching unit 31 is used to control the connection state between at least one of the first live wire L1, the second live wire L2, the third live wire L3, and the control lead wire CP and the ground wire PE. The driving unit 32 is connected to the switching unit 31 and the control module 40. The driving unit 32 is used to supply power to the control module 40 and drive the switching unit 31 according to the leakage current generation signal.

[0049] It should be noted that the drive unit 32 may include a power supply, which provides a supply voltage of, for example, 12V, to power the control module 40. When the control module 40 receives a leakage test command, it can adjust the level of the IO interface connected to the drive unit 32 to notify the drive unit 32 to control the switch unit 31 to generate leakage, or increase the level of the control lead CP to trigger the charging pile output voltage or eliminate the fault.

[0050] In some embodiments, such as Figure 4 As shown, the switching unit 31 includes a first relay K1, a first resistor R1, a second relay K2, and a second resistor R2. The first relay K1 includes a first contact (not shown) and a first coil (not shown). The first contact is connected between the first live wire L1 and the ground wire PE. The first coil is connected to the driving unit 32, which is configured to control the power supply of the first coil. The first resistor R1 is connected in series with the first contact. The second relay K2 includes a second contact (not shown) and a second coil (not shown). The second contact is connected between the control lead CP and the ground wire PE. The second coil is connected to the driving unit 32, which is configured to control the power supply of the second coil. The second resistor R2 is connected in series with the second contact.

[0051] It should be noted that in other embodiments, the relay can also be replaced by a field-effect transistor. The driving unit 32 changes the switching state of the contacts by controlling whether the coil in the relay is energized, thereby realizing the corresponding leakage current test function. For example, when the first coil is energized, the first contact switches from the open state to the closed state, and the first live wire L1 is connected to the ground wire PE through the first contact and the first resistor R1 in sequence, thereby simulating the leakage current of the first live wire L1. When the second coil is energized, the second contact switches from the open state to the closed state, and the level of the control lead CP is pulled low, thereby simulating the plugging and unplugging action, so that the relay of the charging pile closes to supply power normally, or, after the charging pile malfunctions, the fault is eliminated, and then the leakage current of other phase wires can be tested. This embodiment can be applied to the leakage current test of charging piles with single-phase AC charging piles.

[0052] In some embodiments, such as Figure 4 As shown, the switching unit 31 also includes a third relay K3, a third resistor R3, a fourth relay K4, and a fourth resistor R4. The third relay K3 includes a third contact (not shown) and a third coil (not shown). The third contact is connected between the second live wire L2 and the ground wire PE. The third coil is connected to the drive unit 32, which is configured to control the power supply of the third coil. The third resistor R3 is connected in series with the third contact. The fourth relay K4 includes a fourth contact (not shown) and a fourth coil (not shown). The fourth contact is connected between the third live wire L3 and the ground wire PE. The fourth coil is connected to the drive unit 32, which is configured to control the power supply of the fourth coil. The fourth resistor R4 is connected in series with the fourth contact.

[0053] It should be noted that in other embodiments, a field-effect transistor can be used instead of a relay. The driving unit 32 changes the switching state of the contacts by controlling whether the coil in the relay is energized, thereby realizing the corresponding leakage current test function. For example, when the third coil is energized, the third contact switches from the open state to the closed state, and the second live wire L2 is connected to the ground wire PE in sequence through the third contact and the third resistor R3, thereby simulating the leakage current of the second live wire L2. When the fourth coil is energized, the fourth contact switches from the open state to the closed state, and the third live wire L3 is connected to the ground wire PE in sequence through the fourth contact and the fourth resistor R4, thereby simulating the leakage current of the third live wire L3.

[0054] Figure 5 This is a first schematic diagram of the leakage current detection circuit 100 provided in an embodiment of this application. Its specific details are as follows:

[0055] initialization.

[0056] Determine if a leakage current test command has been received: If no leakage current test command has been received, the (equipment) remains in a safe state.

[0057] If a leakage current test instruction is received, the leakage current response time of all three phases is set to the unqualified time, and the leakage current test sequence number is set to L1, that is, the leakage current test is to be performed on the first live wire L1.

[0058] When K1 is closed, the charging gun is simulated to allow charging: normal power is supplied to the coil of the first relay K1 so that the first contact is closed, and normal power is supplied to the coil of the second relay K2 to simulate the normal output of AC power by the charging pile when the charging gun is activated.

[0059] Collect charging pile output voltage: Obtain the line voltage or phase voltage output by the charging pile through the acquisition module.

[0060] Determine if the charging pile is outputting voltage: If the charging pile is not outputting voltage, determine if a timeout has occurred. If no timeout has occurred, proceed to "Collect charging pile output voltage"; if a timeout has occurred, proceed to "Test completed, host computer 150 can read test results".

[0061] If the charging pile outputs voltage, close one leakage current switch (choose one of L1, L2, or L3) according to the test sequence number: Here, leakage current switch refers to the contact connected to the corresponding live wire.

[0062] Collect the output voltage of the charging pile, record the voltage for 50ms (exceeding 2 power frequency synchronizations), and calculate the time from the application of leakage current to the stop of charging.

[0063] Turn off the leakage current, simulate dialing (disconnect K1K2), and wait 6 seconds (the charging station returns to normal from the fault).

[0064] Determine if the 3-way test is complete: The 3-way test refers to the leakage current test of the 3 live wires.

[0065] If the three-channel test is not completed, the test sequence number is incremented by 1, and the next leakage test is performed, i.e., it switches to "K1 closed, simulate charging gun allowed".

[0066] If all three tests are completed, the host computer 150 can read the test results. Then, it will proceed to the next charging station's leakage current test.

[0067] The leakage current detection circuit 100 is compatible with the voltage of a three-phase four-wire or split-phase power grid for detecting power outage time. If leakage occurs in the first live wire L1, the leakage current action time of the first live wire L1 can be approximately equal to the leakage current reaction time minus the action time of the first relay K1.

[0068] The leakage current response time is the time from when the control module 40 triggers the first relay K1 to power on via IO until the charging pile is powered off, which is obtained by timing within the control module 40.

[0069] The action time of the first relay K1 starts counting when the control module 40 triggers the first relay K1 to power on via IO, and ends when the first relay K1 closes. It is generally a fixed value of about 3-4ms.

[0070] Then, the leakage fault of the pile body is eliminated by the second relay K2, and the next leakage test is carried out until the three leakage time tests are completed. Feedback is sent to the host computer 150 to upload the leakage action time of different phases to ground.

[0071] The sequence of actions on the charging pile side is as follows: Initially, the charging pile is in standby mode. The leakage current detection circuit 100 activates the second relay K2 to change the level of the control lead CP, causing the charging pile's relays to close. Subsequently, the first relay K1, the third relay K3, and the fourth relay K4 are triggered to generate leakage current (the leakage time is calculated from this point). The charging pile has a leakage current detection function, which will cause a fault to disconnect the relay of the charging pile. At this time, the leakage current detection circuit 100 will measure the disappearance of the output voltage (this is the end time). Then, the charging gun is simulated for plugging and unplugging to clear the fault. The leakage current action time of the remaining phases is tested in the same way.

[0072] The measurement scheme for leakage current action time is the focus and challenge of this application: since the time from the occurrence to the end of leakage current is in the millisecond (MS) range, the power outage waveforms of different power grids may be inconsistent. The following are power outage waveforms of mains power and split-phase power:

[0073] Figure 6 The waveform of the mains power failure shows that the voltage quickly returns to the zero voltage range after the power failure.

[0074] Figure 7 The waveforms show the voltage drop waveforms of a split-phase power supply, specifically the waveform for voltage drop 1. The arrow indicates the point where the voltage dropped. This demonstrates that after a power drop during the lower half of the sine wave, the voltage slowly recovers to the zero-voltage range, with a relatively long recovery time. These waveforms show that in a split-phase power supply environment, the voltage changes slowly after a power drop and cannot quickly return to the zero-voltage range. Furthermore, the time it takes to return to the zero-voltage range varies significantly depending on the timing of the power drop.

[0075] Graphical analysis revealed that voltage changes slowly after a power outage; when power is restored, the peaks and troughs also change slowly, but with differences. The periods of slow peak and trough changes are shorter, and the rate of change is faster. Therefore, the current method of acquiring analog voltage, which detects a moment of zero voltage and concludes that the charging station has no voltage, may lead to misjudgments under different power outage conditions, causing anomalies and making it unsuitable for accurate identification of defective products in factories.

[0076] By analyzing the waveform and using an algorithm similar to sliding mode filtering, the power outage time is analyzed by first collecting data after the power outage.

[0077] Based on the timing of the power outage, the analysis conclusions are divided into the following three cases:

[0078] 1. In the zero-voltage range, due to the drastic changes in the waveform of alternating current, the difference between 10 consecutive sample values ​​can be less than the first preset value, such as 22, which can easily filter out the power-loss data blocks with almost no error.

[0079] 2. In the region between the peak and the zero voltage range, due to the drastic changes in the AC waveform, the difference between 10 consecutive sample values ​​is less than 22, which can easily filter out the power-loss data blocks with almost no error.

[0080] 3. Near the peaks and troughs, 10 consecutive sample values ​​less than 22 may lead to misjudgment. Figure 8 The waveform of power failure 4 is shown in Table 1, which contains the sampled data for power failure 4. As shown in Table 1, the sampled values ​​after power failure (peaks and troughs) all meet this condition, from number 4 to 26.

[0081] Table 1:

[0082]

[0083] Examining the data sampled after power outages at different times reveals more detailed differences. When power is lost outside the zero-voltage range, the voltage difference from zero is significant, resulting in a prolonged voltage fluctuation (unidirectional increase or decrease with almost no change in direction). Utilizing this property, a judgment condition is added near the peaks and troughs: a power outage is considered only if the "sampling distance" in Table 1 is greater than a second preset value, such as 7. Adding this condition filters out numbers 4 through 8, ultimately revealing that the location corresponding to number 10 differs from our power outage location by only one sampling period (0.2ms).

[0084] In approximately 500 subsequent tests, the response times were found to be between 16.8ms and 20.2ms. The difference was due to the timing of the leakage current application, which caused the sensor (ADC) response to vary. Within 1 / 4 of the power frequency cycle (5ms), the difference was within a reasonable range.

[0085] Calculate the leakage response time of the charging pile, such as Figure 9 As shown:

[0086] Once the data is obtained, calculations begin. The data can be the phase voltage or line voltage sampled from Table 1.

[0087] The filter pointer points to the 0th element of the array. The array refers to a set of sampled values ​​corresponding to indices 1, 2, 3...26 in Table 1.

[0088] Filter the first 10 consecutive data points starting from the pointer, calculate the difference between the maximum and minimum values ​​(Vdiff); calculate the sampling distance between the maximum and minimum values ​​(Sdiff).

[0089] Determine if Vdiff < 22 is true: If Vdiff < 22 is false, check if the filter pointer overflows after incrementing by 1. If it does not overflow, proceed to "Calculate the difference between the maximum and minimum values ​​(Vdiff) for the first 10 consecutive data points from the filter pointer; calculate the sampling distance (Sdiff) where the maximum and minimum values ​​occur". If it overflows, proceed to "Response time = (pointer position at this time - data start position) × 0.2ms; if the pointer overflows, an unacceptable excessive time is obtained".

[0090] If the average of the 10 data points is outside the zero-crossing interval, then EXP_Sdiff = 7; otherwise, EXP_Sdiff = 0. Here, EXP_Sdiff is a second preset value, where 7 can be exemplarily represented as the first value, and 0 can be exemplarily represented as the second value.

[0091] Determine if Vdiff > EXP_Sdiff is true. If not, proceed to "Determine if the filter pointer overflows after incrementing by 1". If true, proceed to "Response time = (pointer position at this time - data start position) × 0.2ms; if the pointer overflows, an unqualified oversized time is obtained".

[0092] Finish.

[0093] In some embodiments, when the AC voltage of the gun holder 10 is the line voltage, the control module 40 is used to determine the leakage response time based on at least one data acquisition block of the line voltage.

[0094] It should be noted that this embodiment is based on Figure 9 As shown, different threshold voltages can be used to determine the power outage time of the power grid based on different power outage timings, which helps to more accurately determine the leakage current response time.

[0095] In some embodiments, the control module 40 obtains the maximum difference and the sampling distance corresponding to the maximum difference in a data block based on the filter pointer. When the maximum difference and the sampling distance both meet the corresponding conditions, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period. The position difference corresponding to the filter pointer is the current position of the filter pointer and the position corresponding to the starting data in the data block.

[0096] It should be noted that the starting data position can be, for example, the position of the 0th data point in the data acquisition block with sequence number 10, i.e., the position of 675. This embodiment provides a method for calculating leakage current response time, which helps to improve the accuracy of the calculation.

[0097] In some embodiments, in the control module 40, the data acquisition block includes multiple data acquisitions, the filter pointer points to the starting data of a data acquisition block, the maximum difference between the maximum and minimum data acquisitions among the multiple data acquisitions is calculated, and the sampling distance between the position of the maximum data acquisition and the position of the minimum data acquisition is calculated; when the maximum difference is less than a first preset value and the sampling distance is greater than a second preset value, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period.

[0098] It should be noted that the first preset value is 22 for example, and the second preset value is 7 for example. The number of data points collected in each data collection block can be an integer such as 2, 3, 4, 5...10.

[0099] In some embodiments, when the average value of multiple collected data is outside the zero-crossing interval, the second preset value is the first value; when the average value of multiple collected data is within the zero-crossing interval, the second preset value is the second value; and the first value is greater than the second value.

[0100] It should be noted that the method used in this embodiment to find power-down data is as follows: first, filter out data blocks where the maximum difference between multiple consecutive sampled values ​​is less than 22 and calculate the sampling distance. If the data is not in the zero-crossing interval, the sampling distance must also be greater than 7. This can avoid incorrect judgment of the power-down time of the charging pile.

[0101] In some embodiments, such as Figure 10 As shown, this embodiment also provides a leakage current detection device 300, which includes the leakage current detection circuit 100 described above.

[0102] It is understood that, since the leakage detection device 300 provided in this embodiment includes the leakage detection circuit 100 described above, when the gun head 210 of the AC charging pile 200 is connected through the gun holder 10, the sampling module 20 detects the AC voltage of the gun holder 10, the leakage generation module 30 simulates the leakage of the AC charging pile 200 and simulates the plugging and unplugging action according to the leakage generation signal, and the control module 40 generates a leakage generation signal according to the leakage test command, and determines the leakage action time of the AC charging pile 200 according to the difference between the leakage reaction time and the leakage generation time of the leakage generation module 30. This not only realizes a highly automated leakage detection process based on a simple structure, reducing the difficulty of leakage detection, but also simplifies the leakage detection process on the basis of high automation, thereby reducing the time spent on leakage detection.

[0103] In some embodiments, such as Figure 11 As shown, the leakage current detection device 300 also includes a host computer 150, which is connected to the control module 40. The host computer 150 is configured to send leakage current test commands and read back the leakage current action time, and determine whether the AC charging pile 200 meets the leakage current protection requirements based on the leakage current action time.

[0104] It should be noted that the host computer 150 and the control module 40 can communicate via, but are not limited to, RS-485, RS-422, or CAN bus. The leakage current detection device 300 can automatically detect leakage current in the AC charging pile 200. Working in conjunction with the host computer 150 on the mass production line, it enables mass production testing of the charging pile's leakage current action time. This allows for timely leakage current detection and action at the source, ensuring compliance with safety standards and significantly improving production efficiency and product safety upon delivery.

[0105] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0106] The leakage current detection circuit 100 and leakage current detection device 300 provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A leakage current detection circuit, characterized in that, The leakage current detection circuit includes: Gun holder, used to connect the charging head of an AC charging station; A sampling module, connected to the gun holder, is used to detect the AC voltage of the gun holder; A leakage current generation module, connected to the gun holder, is used to simulate the leakage current of the AC charging pile and simulate the plugging and unplugging action based on the leakage current generation signal. A control module, connected to the sampling module and the leakage current generation module, is used to generate the leakage current generation signal according to the leakage current test command, and to determine the leakage current action time of the AC charging pile according to the difference between the leakage current response time and the leakage current generation time of the leakage current generation module.

2. The leakage current detection circuit according to claim 1, characterized in that, The control module is used to determine the leakage current response time based on the difference between the generation time of the effective level of the leakage current generation signal and the power-off time of the AC voltage of the gun holder.

3. The leakage current detection circuit according to claim 1, characterized in that, When the AC charging pile is powered by three-phase electricity, the gun holder includes a first live wire, a second live wire, a third live wire, a neutral wire, a ground wire, and a control lead wire. When the AC charging pile is powered by split-phase electricity, the gun holder includes a first live wire, a multi-function wire, a ground wire, and a control guide wire. The multi-function wire is configured as a neutral wire or a second live wire.

4. The leakage current detection circuit according to claim 3, characterized in that, The sampling module is connected to the first live wire, the second live wire, the third live wire, the multi-function wire, and the control module. It is used to sample the phase voltage or line voltage of the gun holder to generate a corresponding sampling voltage and transmit the sampling voltage to the control module.

5. The leakage current detection circuit according to claim 3, characterized in that, The leakage current generation module includes: A switching unit is connected to the first live wire, the second live wire, the third live wire, the ground wire, and the control lead wire, and is used to control the connection state between at least one of the first live wire, the second live wire, the third live wire, and the control lead wire and the ground wire; A drive unit, connected to the switch unit and the control module, is used to supply power to the control module and drive the switch unit according to the leakage current generation signal.

6. The leakage current detection circuit according to claim 5, characterized in that, The switching unit includes: A first relay, comprising a first contact and a first coil, wherein the first contact is connected between the first live wire and the ground wire, and the first coil is connected to the drive unit, the drive unit being configured to control the power supply to the first coil; The first resistor is connected in series with the first contact. The second relay includes a second contact and a second coil. The second contact is connected between the control lead and the ground wire, and the second coil is connected to the drive unit, which is configured to control the power supply to the second coil. The second resistor is connected in series with the second contact.

7. The leakage current detection circuit according to claim 6, characterized in that, The switching unit further includes: The third relay includes a third contact and a third coil. The third contact is connected between the second live wire and the ground wire. The third coil is connected to the drive unit, which is configured to control the power supply of the third coil. The third resistor is connected in series with the third contact. The fourth relay includes a fourth contact and a fourth coil. The fourth contact is connected between the third live wire and the ground wire. The fourth coil is connected to the drive unit, which is configured to control the power supply of the fourth coil. The fourth resistor is connected in series with the fourth contact.

8. The leakage current detection circuit according to any one of claims 1-7, characterized in that, When the AC voltage of the gun holder is the line voltage, the control module is used to determine the leakage current response time based on at least one data block of the line voltage.

9. The leakage current detection circuit according to claim 8, characterized in that, The control module obtains the maximum difference in the acquired data block and the sampling distance corresponding to the maximum difference based on the filter pointer. When the maximum difference and the sampling distance both satisfy the corresponding conditions, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period. The position difference corresponding to the filter pointer is the current position of the filter pointer and the position corresponding to the starting data in the acquired data block.

10. The leakage current detection circuit according to claim 9, characterized in that, In the control module, the data acquisition block includes multiple data acquisitions, the filter pointer points to the starting data of the data acquisition block, the maximum difference between the maximum and minimum data acquisitions among the multiple data acquisitions is calculated, and the acquisition distance between the position of the maximum data acquisition and the position of the minimum data acquisition is calculated. When the maximum difference is less than the first preset value and the sampling distance is greater than the second preset value, the leakage current response time is determined to be the product of the position difference corresponding to the filter pointer and the sampling period.

11. The leakage current detection circuit according to claim 10, characterized in that, When the average value of the multiple collected data is outside the zero-crossing interval, the second preset value is the first value; when the average value of the multiple collected data is within the zero-crossing interval, the second preset value is the second value; the first value is greater than the second value.

12. A leakage current detection device, characterized in that, The leakage current detection device includes the leakage current detection circuit as described in any one of claims 1-11.

13. The leakage current detection device according to claim 12, characterized in that, The leakage current detection device also includes a host computer, which is connected to the control module. The host computer is configured to send the leakage current test command and read back the leakage current action time, and determine whether the AC charging pile meets the leakage current protection requirements based on the leakage current action time.

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