A multi-level leakage protection circuit, system and leakage self-recovery method

Abstract

The present application provides a multi-level leakage protection circuit, system and leakage self-recovery method, the multi-level leakage protection circuit includes: a first circuit, N second circuits, wherein N is an integer greater than 1; the N second circuits are connected in parallel, and the first circuit is connected in series with the N second circuits connected in parallel; the first circuit includes a first leakage current sensor, the first leakage current sensor is used to detect a leakage fault in the first circuit, each second circuit includes at least one second leakage current sensor, the second leakage current sensor is used to detect a leakage fault in the second circuit, wherein when the second leakage current sensor detects that the second circuit has a leakage fault, the second circuit with the leakage fault is disconnected, and when the first circuit has a leakage fault or the second circuit has a leakage fault and the second circuit with the leakage fault is not disconnected, the first circuit is disconnected.

Description

Technical Field

[0001] The present application relates to the field of charging technology, and in particular to a multi-level leakage protection circuit, system and leakage self-recovery method. Background Art

[0002] As a convenient means of transportation for short-distance travel, two-wheeled electric vehicles have penetrated into many fields such as personal travel, instant delivery, and shared travel, and the market size continues to grow. At the same time, the problems of difficulty in charging and parking of two-wheeled electric vehicles are becoming more and more prominent. At present, two-wheeled electric vehicles are mainly charged through charging cabinets, and one charging cabinet can charge multiple two-wheeled electric vehicles at the same time. Since the system in the charging cabinet is only equipped with a leakage protection design for the main incoming line circuit, when a single charging compartment leaks, it will cause the entire charging cabinet to lose power, affecting the overall operation of the equipment, affecting the user experience and causing serious safety hazards. Summary of the invention

[0003] The embodiments of the present application provide a multi-level leakage protection circuit, system and leakage self-recovery method to solve the problem that leakage of a single charging compartment causes power failure of the entire charging cabinet and affects the overall operation of the equipment.

[0004] To solve the above technical problems, this application is implemented as follows:

[0005] In a first aspect, the present application provides a multi-stage leakage protection circuit, the multi-stage leakage protection circuit comprising:

[0006] a first circuit, and N second circuits, wherein N is an integer greater than 1;

[0007] N second circuits are connected in parallel, and the first circuit and the N second circuits connected in parallel are connected in series;

[0008] The first circuit includes a first leakage current sensor, which is used to detect a leakage fault in the first circuit. Each of the second circuits includes at least one second leakage current sensor, which is used to detect a leakage fault in the second circuit. When the second leakage current sensor detects that the second circuit has a leakage fault, the second circuit with the leakage fault is disconnected. When the first circuit has a leakage fault or the second circuit has a leakage fault and the second circuit with the leakage fault is not disconnected, the first circuit is disconnected.

[0009] Optionally, it also includes a low-voltage leakage current detection circuit, wherein the first circuit is connected in series with N second circuits connected in parallel to obtain a third circuit, and the third circuit is connected in parallel with the low-voltage leakage current detection circuit. The low-voltage leakage current detection circuit is used to detect the insulation resistance value of the first circuit with a leakage fault or the insulation resistance value of the second circuit, or to detect a leakage fault in the disconnected second circuit.

[0010] Optionally, the low-voltage leakage current detection circuit includes an insulation resistance detection bridge circuit and a relay, the input end of the insulation resistance detection bridge circuit is connected to the input end of the third circuit, the output end of the insulation resistance detection bridge circuit is connected to the input end of the relay, and the output end of the relay is connected to the output end of the third circuit.

[0011] Optionally, the first circuit also includes a first leakage protector, and each of the second circuits also includes a second leakage protector, the first leakage protector is used to perform leakage protection when a leakage fault exists in the first circuit, and the second leakage protector is used to perform leakage protection when a leakage fault exists in the second circuit where the second leakage protector is located, wherein the action time of the first leakage protector is greater than the action time of the second leakage protector.

[0012] In a second aspect, the present application also includes a leakage protection system, which includes the multi-level leakage protection circuit in the above-mentioned first aspect.

[0013] In a third aspect, the present application also includes a leakage self-recovery method, which is applied to the multi-level leakage protection circuit in the first aspect, and the method includes the following steps:

[0014] Obtaining a current value in the first circuit and a current value in each of N second circuits, where N is an integer greater than 1;

[0015] When the current value of the second target circuit is greater than the preset first current threshold, disconnecting the second target circuit, where the second target circuit is any one of the N second circuits;

[0016] In the case where the current value of each second circuit is less than or equal to the preset first current threshold, determining whether the current value of the first circuit is greater than the preset second current threshold;

[0017] When the current value of the first circuit is greater than the preset second current threshold, the first circuit is disconnected.

[0018] Optionally, each of the second circuits includes a second leakage protector and at least one second leakage current sensor, and when the current value of the second target circuit is greater than the preset first current threshold, disconnecting the second target circuit includes:

[0019] acquiring a current value of each of the second circuits based on the second leakage current sensor;

[0020] When the current value of the second target circuit is greater than the preset first current threshold, the second target circuit is disconnected based on the second leakage protector in the second target circuit.

[0021] Optionally, before disconnecting the second target circuit based on the second leakage protector in the second target circuit, the method further includes:

[0022] Based on the low-voltage leakage current detection circuit, detecting whether there is a leakage fault in the second circuit;

[0023] When there is a leakage fault in the second circuit, closing M second circuits among the N second circuits, and obtaining a current value of each second circuit among the M second circuits;

[0024] Comparing a first sum of current values ​​of each of the M second circuits with a preset third current threshold;

[0025] When the first sum is greater than the preset third current threshold, close K of the M second circuits to obtain a current value of each of the K second circuits, wherein N is greater than M, M is greater than K, M is an integer greater than 1, and K is an integer greater than 1;

[0026] Comparing a second sum of current values ​​of each of the K second circuits with a preset fourth current threshold, and closing Q of the K second circuits when the second sum is greater than the preset fourth current threshold, wherein K is greater than Q, and Q is an integer greater than 1;

[0027] When Q is 1, the closed second circuit is determined to be the second target circuit.

[0028] Optionally, the first circuit includes a first leakage current sensor, and the second target circuit is disconnected based on the second leakage protector in the second target circuit, further comprising:

[0029] In the case that the second leakage protector disconnects the second target circuit abnormally, detecting a current value in the first circuit within a preset time based on the first leakage current sensor;

[0030] When the current value in the first circuit continues to be greater than the preset safety threshold within the preset time, the access end of the second target circuit is disconnected.

[0031] Optionally, the multi-stage leakage protection circuit further includes a low-voltage leakage current detection circuit, the low-voltage leakage current detection circuit includes an insulation resistance detection bridge circuit and a relay, and when the current value of the first circuit is greater than the preset second current threshold, after disconnecting the first circuit, it also includes:

[0032] closing the isolating switch of the relay;

[0033] Based on the insulation resistance detection bridge circuit, detecting the resistance value of the insulation resistance in the second target circuit, and when the resistance value of the insulation resistance in the second target circuit is greater than a preset first resistance value, closing the second target circuit and disconnecting the isolating switch of the relay;

[0034] or,

[0035] Based on the insulation resistance detection bridge circuit, the resistance value of the insulation resistor in the first circuit is detected. When the resistance value of the insulation resistor in the first circuit is greater than a preset second resistance value, the first circuit is closed and the isolating switch of the relay is opened.

[0036] In an embodiment of the present application, the multi-stage leakage protection circuit includes a two-stage circuit, namely a first circuit and N second circuits, the N second circuits are connected in parallel, and the first circuit is connected in series with the N second circuits connected in parallel. The first circuit and the second circuit respectively include a first leakage current sensor and a second leakage current sensor, and the first leakage sensor is used to detect leakage faults in the first circuit as a first-level leakage protection. The second leakage current sensor is used to detect leakage faults in the second circuit as a second-level leakage protection. Through the above-mentioned two-level circuit protection, the power-off probability of the first circuit can be minimized to the greatest extent, and the normal use of other second circuits can be prevented from being affected by leakage of a single second circuit, and the interactivity between the system and the customer can be enhanced, which can effectively ensure the relative safety of the equipment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0038] Figure 1 This is one of the structural schematic diagrams of a multi-level leakage protection circuit provided in an embodiment of the present application;

[0039] Figure 2 This is the second structural schematic diagram of a multi-level leakage protection circuit provided in an embodiment of the present application;

[0040] Figure 3 This is the third structural schematic diagram of a multi-level leakage protection circuit provided in an embodiment of the present application;

[0041] Figure 4 This is the fourth structural diagram of a multi-level leakage protection circuit provided in an embodiment of the present application;

[0042] Figure 5 This is one of the flow charts of a leakage self-recovery method provided in an embodiment of the present application;

[0043] Figure 6 This is the second flow chart of a leakage self-recovery method provided in an embodiment of the present application;

[0044] Figure 7 This is a third flow chart of a leakage self-recovery method provided in an embodiment of the present application;

[0045] Figure 8 It is a schematic diagram of the structure of the insulation resistance detection bridge circuit;

[0046] The reference numerals are as follows:

[0047] 11: first circuit; 111: first leakage current sensor; 112: first leakage protector; 12: second circuit; 121: second leakage current sensor; 122: second leakage protector; 13: third circuit; 14: low voltage leakage current detection circuit; 141: insulation resistance detection bridge circuit; 142: relay. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Therefore, it should be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present application.

[0049] The present application provides a multi-level leakage protection circuit, system and leakage self-recovery method. Figure 1 and Figure 2 ,like Figure 1 and Figure 2As shown, the multi-stage leakage protection circuit includes:

[0050] N second circuits 12 are connected in parallel, and the first circuit 11 is connected in series with the N second circuits 12 connected in parallel;

[0051] The first circuit 11 includes a first leakage current sensor 111, which is used to detect a leakage fault in the first circuit 11. Each of the second circuits 12 includes at least one second leakage current sensor 121, which is used to detect a leakage fault in the second circuit 12. When the second leakage current sensor 121 detects that the second circuit 12 has a leakage fault, the second circuit 12 with the leakage fault is disconnected. When the first circuit 11 has a leakage fault or the second circuit 12 has a leakage fault and the second circuit 12 with the leakage fault is not disconnected, the first circuit 11 is disconnected.

[0052] In a specific embodiment of the present application, the multi-level leakage protection circuit includes a first circuit 11 and N second circuits 12, the N second circuits 12 are connected in parallel, each second circuit 12 can be used as a branch, and the N second circuits 12 can be connected in series with the first circuit 11 as the main circuit. At the same time, the first circuit 11 includes a first leakage current sensor 111, and the first leakage current sensor 111 can be used to detect a leakage fault in the first circuit 11. The second circuit 12 includes a second leakage current sensor 121, and the second leakage current sensor 121 can be used to detect a leakage fault in the second circuit 12. The input end of the first circuit 11 can be connected to the AC main incoming line, and the output end of each second circuit 12 can be connected to the user's charging device. The second circuit 12 with a leakage fault can be disconnected in time through the secondary leakage protection setting, so that other second circuits 12 can continue to work normally, preventing the first circuit 11 from disconnecting the device for leakage protection, causing the entire device to be powered off, and reducing the possibility of problems caused by a single second circuit 12 affecting the overall work.

[0053] It should be noted that, in the process of circuit operation, there is a sudden leakage, and the second leakage current sensor 121 detects the current value in the branch where it is located. When a leakage fault is detected, the second circuit 12 where it is located will be disconnected. If there is an abnormal leakage protection of the second circuit 12, the first leakage current sensor 111 in the first circuit 11 detects that there is a leakage fault in the circuit, and the first circuit 11 will be disconnected, and all second circuits 12 will be cut off to prevent the leakage fault from continuing to exist and eliminate safety hazards. The above-mentioned first circuit 11 may also include a main incoming air switch, an electric operating mechanism, a release, etc. When it is necessary to disconnect the first circuit 11, the main incoming air switch is turned on to disconnect the entire circuit. In addition, the multi-stage leakage protection circuit may also include a controller, which can record the leakage current of each second circuit 12 in detail during operation. This data is stored in the controller as part of the safety data. At the same time, the controller has a power-off retention function, which can record the state of each second circuit 12 before power failure, which is used to determine the source of the leakage current.

[0054] Specifically, since each second circuit 12 is connected to a different user charging device, when a leakage fault occurs in the user's own charging device, when the user accesses the system, the system detects the leakage current through the second leakage current sensor 121. When the leakage current monitoring in the second circuit 12 exceeds the set threshold at the moment of closing, the second circuit 12 will be disconnected to prevent the first circuit 11 from being disconnected. At the same time, the controller records the second circuit 12 and issues an abnormal alarm.

[0055] Optionally, it also includes a low-voltage leakage current detection circuit 14, the first circuit 11 and N second circuits 12 connected in parallel are connected in series to obtain a third circuit 13, the third circuit 13 is connected in parallel with the low-voltage leakage current detection circuit 14, and the low-voltage leakage current detection circuit 14 is used to detect the insulation resistance value of the first circuit 11 or the insulation resistance value of the second circuit 12 with a leakage fault, or to detect a leakage fault in the disconnected second circuit 12.

[0056] Please refer to Figure 3 , Figure 3It is the third structural schematic diagram of a multi-stage leakage protection circuit provided by an embodiment of the present application. In a specific embodiment of the present application, the multi-stage leakage protection circuit also includes a low-voltage leakage current detection circuit 14, which is connected in series with the first circuit 11 and the second circuit 12 connected in parallel with N to obtain a third circuit 13 connected in parallel. The low-voltage leakage current detection circuit 14 can be specifically used to detect the insulation resistance value of the first circuit 11 with a leakage fault or the insulation resistance value of the second circuit 12, or to detect the leakage fault in the disconnected second circuit 12. Specifically, by measuring the resistance value of the insulation resistance in the first circuit 11 or the second circuit 12, it is determined whether there is a leakage safety hazard in the circuit with a leakage fault, and whether the leakage fault is restored, which can effectively ensure the safety of the circuit during the second power-on. Secondly, a leakage current sensor can be set in the low-voltage leakage current detection circuit 14 to detect the leakage fault in the second circuit 12 of the disconnected card.

[0057] Optionally, the low-voltage leakage current detection circuit 14 includes an insulation resistance detection bridge circuit 141 and a relay 142, the input end of the insulation resistance detection bridge circuit 141 is connected to the input end of the third circuit 13, the output end of the insulation resistance detection bridge circuit 141 is connected to the input end of the relay 142, and the output end of the relay 142 is connected to the output end of the third circuit 13.

[0058] Specifically, the low-voltage leakage current detection circuit 14 can use a low voltage input, measure and calculate the insulation resistance of the first circuit 11 or the second circuit 12 through the insulation resistance detection bridge circuit 141, and the controller compares the size of the equivalent insulation resistance with the safety threshold to determine whether the leakage fault has been restored, thereby realizing the self-recovery function. In addition, the low-voltage leakage current detection circuit 14 may include a leakage current sensor, a relay 142, and an insulation resistance detection bridge circuit 141. The role of the leakage current sensor in the low-voltage leakage current detection circuit 14 is to detect the leakage fault in the second circuit 12 of the broken card; the main role of the isolating switch is to disconnect the detection circuit from the first circuit 11 during the normal operation of the equipment to ensure electrical safety isolation; the insulation resistance detection bridge circuit 141 is used to monitor the insulation resistance in the first circuit 11 or the second circuit 12.

[0059] Optionally, the first circuit 11 also includes a first leakage protector 112, and each of the second circuits 12 also includes a second leakage protector 122, the first leakage protector 112 is used to perform leakage protection when a leakage fault exists in the first circuit 11, and the second leakage protector 122 is used to perform leakage protection when a leakage fault exists in the second circuit 12 where the second leakage protector 122 is located, wherein the action time of the first leakage protector 112 is greater than the action time of the second leakage protector 122.

[0060] Please refer to Figure 4 , Figure 4 This is the fourth structural diagram of a multi-level leakage protection circuit provided by an embodiment of the present application, specifically including: the first circuit 11 and the second circuit 12 may also be provided with a first leakage protector 112 and a second leakage protector 122, respectively, and the action time of the leakage protector is set to monitor whether the leakage fault persists. First, the leakage fault is detected by the second circuit 12, and the action time of the second leakage protector 122 is set. Secondly, the action time of the first leakage protector 112 in the first circuit 11 is set to be greater than the action time of the second leakage protector 122, so that it can be judged whether the leakage fault has been restored or persists, and the protection circuit is safe. When the first circuit 11 and the second circuit 12 are both disconnected, the action time of the first leakage protector 112 and the action time of the second leakage protector 122 are set, and the low-voltage leakage current detection circuit 14 is used to quickly detect whether there is a fault in the current first circuit 11, which can ensure that the equipment system is relatively safe, effectively reduce the risk of electric shock to personnel, and have multiple protection levels and fast action response.

[0061] See also Figure 5 , Figure 5 This is one of the flow charts of a leakage self-recovery method provided in an embodiment of the present application, which is applied to a multi-level leakage protection circuit as in the above embodiment. The method comprises the following steps:

[0062] Step 21: Obtain a current value in the first circuit and a current value in each of N second circuits, where N is an integer greater than 1.

[0063] Step 22: When the current value of the second target circuit is greater than a preset first current threshold, disconnect the second target circuit, where the second target circuit is any one of the N second circuits.

[0064] Step 23: When the current value of each second circuit is less than or equal to the preset first current threshold, determine whether the current value of the first circuit is greater than the preset second current threshold.

[0065] Step 24: When the current value of the first circuit is greater than the preset second current threshold, disconnect the first circuit.

[0066] See also Figure 6 , Figure 6 This is the second flow chart of a leakage self-recovery method provided in an embodiment of the present application, and the specific steps include:

[0067] Step 31: There is a current value of the second target circuit that is greater than a preset first current threshold;

[0068] Step 32: disconnect the second target circuit if the current value of the second target circuit is less than the preset first current threshold;

[0069] Step 33: If the current value of the second target circuit is greater than the preset first current threshold, determine whether the current value of the first circuit is greater than the preset second current threshold;

[0070] Step 34: If the current value of the first circuit is greater than the preset second current threshold, disconnect the first circuit.

[0071] In the above Figure 5 and Figure 6 In a specific embodiment, the current value in the first circuit and the current value in the second circuit can be obtained respectively by using the first leakage current sensor in the first circuit and the second leakage current sensor in the second circuit. First, by comparing whether the current value in the second circuit exceeds the threshold value, it is determined whether there is a leakage fault in the second circuit. When there is a current value in the second circuit that is greater than the preset first current value, it indicates that there is a leakage fault in the second circuit, and the second circuit is disconnected, and the disconnected second circuit can be determined as the second target circuit. The second target circuit is any one of the N second circuits, and the second target circuit can be one or more. Subsequently, if the second leakage current sensor does not detect the second circuit with a leakage fault, the first leakage current sensor is used to determine whether there is a leakage fault in the first circuit. When the current value of the first circuit is greater than the preset second current threshold, it indicates that there is a leakage fault in the first circuit, and the circuit safety is protected by disconnecting the first circuit. In this way, by applying a leakage self-recovery method in a multi-level leakage protection circuit, the first circuit and the second circuit can be effectively monitored, the faulty circuit can be checked, the risk of electric shock to personnel can be reduced, and the circuit safety can be guaranteed. It can also minimize the probability of power failure of the first circuit, prevent the normal use of other second circuits from being affected by leakage of a single second circuit, ensure the relative safety of the system where the circuit is located, and reduce safety hazards.

[0072] Optionally, each of the second circuits includes a second leakage protector and at least one second leakage current sensor, and when the current value of the second target circuit is greater than the preset first current threshold, disconnecting the second target circuit includes:

[0073] acquiring a current value of each of the second circuits based on the second leakage current sensor;

[0074] When the current value of the second target circuit is greater than the preset first current threshold, the second target circuit is disconnected based on the second leakage protector in the second target circuit.

[0075] In an embodiment of the present application, the second leakage protector and the second leakage current sensor in the above-mentioned second circuit are used in the second circuit to disconnect the second circuit and detect the leakage fault of the second circuit when a leakage fault occurs in the second circuit, respectively. The specific effects are consistent with the above-mentioned multi-stage leakage protection circuit embodiment and will not be repeated here.

[0076] Optionally, before disconnecting the second target circuit based on the second leakage protector in the second target circuit, the method further includes:

[0077] Based on the low-voltage leakage current detection circuit, detecting whether there is a leakage fault in the second circuit;

[0078] When there is a leakage fault in the second circuit, closing M second circuits among the N second circuits, and obtaining a current value of each second circuit among the M second circuits;

[0079] Comparing a first sum of current values ​​of each of the M second circuits with a preset third current threshold;

[0080] When the first sum is greater than the preset third current threshold, close K of the M second circuits to obtain a current value of each of the K second circuits, wherein N is greater than M, M is greater than K, M is an integer greater than 1, and K is an integer greater than 1;

[0081] Comparing a second sum of current values ​​of each of the K second circuits with a preset fourth current threshold, and closing Q of the K second circuits when the second sum is greater than the preset fourth current threshold, wherein K is greater than Q, and Q is an integer greater than 1;

[0082] When Q is 1, the closed second circuit is determined to be the second target circuit.

[0083] For example, M can be half of N, K can be half of M, and Q can be half of K. If there is a sudden leakage in a second circuit during use, and the second leakage protector in the second circuit is abnormal and does not cut off the second circuit in time, the second circuit detects a leakage fault, so that the first leakage protector works to disconnect the first circuit. Then, by cutting off all the second circuits and waiting for the set delay, a low-voltage leakage current detection circuit is used to detect whether there is a leakage fault in the second circuit. If the leakage fault still exists, through the above-mentioned settings of M, K and Q, the low-voltage leakage monitoring of each branch can be performed one by one by binary division. According to the saved records of the controller, the second circuits before the fault are closed first, and the first leakage sensor detects whether the current in the first circuit is lower than the preset third current threshold. If it is lower than the preset third current threshold, it means that the second circuit of the group is normal, and then try to close half of the remaining second circuits, and so on, until the second circuit with a specific actual leakage fault is detected. Finally, the controller can mark the fault of the second circuit and report the alarm, and the controller closes the switches of the first circuit and other second circuits to restore the normal operation of the circuit.

[0084] To continue with the example, when there is a leakage fault in the user's own charging device, the user connects to a second circuit, and the second leakage current sensor in the second circuit detects the presence of a leakage current fault. At the same time, the second leakage protector abnormally fails to cut off the second circuit in time, and then monitors the leakage fault through the first leakage current sensor in the first circuit. When the leakage current detected by the first leakage current sensor continues to exceed the preset second current threshold, the multi-level leakage protection circuit will automatically disconnect the second circuit connected to the current user and continue to monitor. If the current in the first circuit returns to the safety threshold, the leakage fault of the second circuit is recorded and an alarm is reported, and other second circuits remain in normal operation. If the system monitors that the current in the first circuit still exceeds the preset second current threshold, then each circuit is detected and the fault branch is checked according to the dichotomy method in the above example, and the second target circuit is finally determined to solve the leakage safety problem in the multi-level leakage protection circuit.

[0085] Optionally, the first circuit includes a first leakage current sensor, and the second target circuit is disconnected based on the second leakage protector in the second target circuit, further comprising:

[0086] In the case that the second leakage protector disconnects the second target circuit abnormally, detecting a current value in the first circuit within a preset time based on the first leakage current sensor;

[0087] When the current value in the first circuit continues to be greater than the preset safety threshold within the preset time, the access end of the second target circuit is disconnected.

[0088] It is understandable that in the case where the second leakage protector disconnects the second target circuit abnormally, that is, there is a leakage fault in the second circuit and the second leakage protector fails to disconnect the second circuit, the current value in the first circuit is detected by the first leakage current sensor in the first circuit. Within the above preset time, the current value in the first circuit detected by the first leakage current sensor is more accurate and reliable. Disconnecting the access end of the second target circuit disconnects the second target circuit from the charging device, reducing the possibility of the entire circuit failing due to leakage in the second circuit or leakage in the charging device connected to the second target circuit, and preventing the normal use of other second circuits from being affected by leakage in a single second circuit.

[0089] Optionally, the multi-stage leakage protection circuit further includes a low-voltage leakage current detection circuit, the low-voltage leakage current detection circuit includes an insulation resistance detection bridge circuit and a relay, and when the current value of the first circuit is greater than the preset second current threshold, after disconnecting the first circuit, it also includes:

[0090] closing the isolating switch of the relay;

[0091] Based on the insulation resistance detection bridge circuit, detecting the resistance value of the insulation resistance in the second target circuit, and when the resistance value of the insulation resistance in the second target circuit is greater than a preset first resistance value, closing the second target circuit and disconnecting the isolating switch of the relay;

[0092] or,

[0093] Based on the insulation resistance detection bridge circuit, the resistance value of the insulation resistor in the first circuit is detected. When the resistance value of the insulation resistor in the first circuit is greater than a preset second resistance value, the first circuit is closed and the isolating switch of the relay is opened.

[0094] See also Figure 7 , Figure 7 This is a flow chart of a leakage self-recovery method provided in an embodiment of the present application, and the specific steps include:

[0095] Step 41, closing the isolating switch of the relay;

[0096] Step 42: Detect the resistance value of the insulation resistance in the second target circuit based on the insulation resistance detection bridge circuit;

[0097] Step 43, determining that the resistance value of the insulation resistance in the second target circuit is greater than the preset first resistance value;

[0098] Step 44, closing the second target circuit and opening the isolating switch of the relay;

[0099] Step 45, detecting the resistance value of the insulation resistance in the first circuit based on the insulation resistance detection bridge circuit;

[0100] Step 46, determining that the resistance value of the insulation resistance in the first circuit is greater than a preset second resistance value;

[0101] Step 47: close the first circuit and open the isolating switch of the relay.

[0102] In the above embodiment of the present application, during normal operation of the device, the isolating switch of the relay can ensure that the low-voltage leakage current detection circuit is disconnected from the first circuit. When the first circuit is disconnected, the low-voltage leakage current detection circuit is started.

[0103] See also Figure 8 , Figure 8 It is a structural diagram of the insulation resistance detection bridge circuit. In the insulation resistance detection bridge circuit, close switches K1 and K2 at the same time for quick detection, because the detection resistance is much smaller than the insulation resistance. If the detection voltage U1 is not equal to half of the total voltage, it means that the grounding resistance is abnormal. The specific detection error needs to be judged according to the actual situation, and this application does not limit it. If the insulation of the neutral wire and the live wire to the ground drops at the same time, the leakage equivalent resistance needs to be calculated. The specific method is as follows:

[0104] First, disconnect the first switch and only close the second switch. Set the total voltage in the low-voltage leakage current detection circuit to 24V. The relationship between resistance and voltage is: Then the second switch is opened and only the first switch is closed. The relationship between resistance and voltage is: By combining the above two equations, the size of the measured leakage equivalent resistance R1 and R2 can be obtained.

[0105] Where U1 is the known voltage to be measured;

[0106] R1 is the equivalent resistance;

[0107] R2 is the equivalent resistance;

[0108] R3 is the resistance to be measured;

[0109] R4 is the resistance to be measured.

[0110] It is worth mentioning that the above detection voltage can be a DC voltage or an AC voltage of a specific frequency, respectively testing the equivalent resistance of the circuit at an AC specific frequency and the DC equivalent resistance.

[0111] It can be understood that the leakage equivalent resistance calculated by the above method is compared with the safety threshold. If the leakage equivalent resistance is less than the safety resistance, it means that the leakage has not been restored. At this time, the AC circuit breaker will not take any action to ensure the safety of the entire equipment system and prevent people from contacting and causing electric shock. First, set the safety resistance, which can be a preset first resistance value and a preset second resistance value, and is determined according to the resistance value of the circuit at the beginning and during operation. If the leakage equivalent resistance is greater than the safety resistance, it means that the leakage has been restored. At this time, the isolating switch of the relay is disconnected, and the first circuit or the second circuit is closed to realize the self-recovery function and reduce the safety hazards caused by human operation.

[0112] An embodiment of the present application also provides a leakage protection system, which includes the multi-level leakage protection circuit in the above embodiment. At the same time, the leakage protection system can apply the above leakage self-recovery method. Therefore, the leakage protection system provided by this embodiment has all the beneficial effects of all the above embodiments, which will not be repeated here.

[0113] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present invention, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0114] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0115] In the several embodiments provided in the present application, it should be understood that the disclosed circuits, systems and methods can be implemented in other ways. The system embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0116] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0117] In addition, all functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0118] A person skilled in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, etc., various media that can store program codes.

[0119] Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention can be essentially or partly reflected in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a device (which can be a terminal or a platform, etc.) to execute all or part of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0120] The above is only an embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A multi-level leakage protection circuit, characterized in that: include: A first circuit and N second circuits, wherein N is an integer greater than 1; N second circuits are connected in parallel, and the first circuit and the N second circuits connected in parallel are connected in series; The first circuit includes a first leakage current sensor, and the first leakage current sensor is used to detect a leakage fault in the first circuit. Each of the second circuits includes at least one second leakage current sensor, and the second leakage current sensor is used to detect a leakage fault in the second circuit. When the second leakage current sensor detects that the second circuit has a leakage fault, the second circuit with the leakage fault is disconnected. When the first circuit has a leakage fault or the second circuit has a leakage fault, and the second circuit with the leakage fault is not disconnected, the first circuit is disconnected. The multi-level leakage protection circuit also includes a low-voltage leakage current detection circuit. The first circuit is connected in series with N second circuits connected in parallel to obtain a third circuit. The third circuit is connected in parallel with the low-voltage leakage current detection circuit. The low-voltage leakage current detection circuit is used to detect the insulation resistance value of the first circuit with a leakage fault or the insulation resistance value of the second circuit, or to detect a leakage fault in the disconnected second circuit.

2. The circuit according to claim 1, characterized in that The low-voltage leakage current detection circuit includes an insulation resistance detection bridge circuit and a relay. The input end of the insulation resistance detection bridge circuit is connected to the input end of the third circuit, the output end of the insulation resistance detection bridge circuit is connected to the input end of the relay, and the output end of the relay is connected to the output end of the third circuit.

3. The circuit according to claim 1, characterized in that The first circuit also includes a first leakage protector, and each of the second circuits also includes a second leakage protector. The first leakage protector is used to perform leakage protection when a leakage fault exists in the first circuit, and the second leakage protector is used to perform leakage protection when a leakage fault exists in the second circuit where the second leakage protector is located, wherein the action time of the first leakage protector is greater than the action time of the second leakage protector.

4. A multi-level leakage protection system, characterized in that: The system comprises the multi-stage leakage protection circuit according to any one of claims 1 to 3.

5. A leakage self-recovery method, applied to the multi-stage leakage protection circuit as claimed in any one of claims 1 to 3, characterized in that: include: Obtaining a current value in the first circuit and a current value in each of N second circuits, where N is an integer greater than 1; When the current value of the second target circuit is greater than the preset first current threshold, disconnecting the second target circuit, where the second target circuit is any one of the N second circuits; In the case where the current value of each second circuit is less than or equal to the preset first current threshold, determining whether the current value of the first circuit is greater than the preset second current threshold; When the current value of the first circuit is greater than the preset second current threshold, the first circuit is disconnected.

6. The method according to claim 5, characterized in that Each of the second circuits includes a second leakage protector and at least one second leakage current sensor, and when the current value of the second target circuit is greater than the preset first current threshold, disconnecting the second target circuit includes: acquiring a current value of each of the second circuits based on the second leakage current sensor; When the current value of the second target circuit is greater than the preset first current threshold, the second target circuit is disconnected based on the second leakage protector in the second target circuit.

7. The method according to claim 6, characterized in that Before disconnecting the second target circuit based on the second leakage protector in the second target circuit, the method further includes: Based on the low-voltage leakage current detection circuit, detecting whether there is a leakage fault in the second circuit; When there is a leakage fault in the second circuit, closing M second circuits among the N second circuits, and obtaining a current value of each second circuit among the M second circuits; Comparing a first sum of current values ​​of each of the M second circuits with a preset third current threshold; When the first sum is greater than the preset third current threshold, close K of the M second circuits to obtain a current value of each of the K second circuits, wherein N is greater than M, M is greater than K, M is an integer greater than 1, and K is an integer greater than 1; Comparing a second sum of current values ​​of each of the K second circuits with a preset fourth current threshold, and closing Q of the K second circuits when the second sum is greater than the preset fourth current threshold, wherein K is greater than Q, and Q is an integer greater than 1; When Q is 1, the closed second circuit is determined to be the second target circuit.

8. The method according to claim 6, characterized in that The first circuit includes a first leakage current sensor, and the second target circuit is disconnected based on the second leakage protector in the second target circuit, and further includes: In the case that the second leakage protector disconnects the second target circuit abnormally, detecting a current value in the first circuit within a preset time based on the first leakage current sensor; When the current value in the first circuit continues to be greater than the preset safety threshold within the preset time, the access end of the second target circuit is disconnected.

9. The method according to claim 5, characterized in that The multi-stage leakage protection circuit further includes a low-voltage leakage current detection circuit, which includes an insulation resistance detection bridge circuit and a relay. When the current value of the first circuit is greater than the preset second current threshold, after disconnecting the first circuit, the circuit further includes: closing the isolating switch of the relay; Based on the insulation resistance detection bridge circuit, detecting the resistance value of the insulation resistance in the second target circuit, and when the resistance value of the insulation resistance in the second target circuit is greater than a preset first resistance value, closing the second target circuit and disconnecting the isolating switch of the relay; or, Based on the insulation resistance detection bridge circuit, the resistance value of the insulation resistor in the first circuit is detected. When the resistance value of the insulation resistor in the first circuit is greater than a preset second resistance value, the first circuit is closed and the isolating switch of the relay is opened.

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