An alternating current power leakage detection method and circuit and a vehicle-mounted charger

Abstract

The application provides an alternating current power detection circuit, method and vehicle-mounted charger. In response to a user's power-on operation on an alternating current power supply, a first sampling signal is obtained, the first sampling signal including a sampling signal of a first sampling point and a sampling signal of a second sampling point. Impedance matching and hardware filtering are performed on the first sampling signal to obtain a second sampling signal. Software filtering is performed on the second sampling signal to obtain a third sampling signal, the third sampling signal including a voltage effective value and a voltage peak value of the first sampling point and a voltage effective value and a voltage peak value of the second sampling point. When the deviation between the voltage effective value of the first sampling point and the voltage effective value of the second sampling point is greater than or equal to a preset voltage deviation threshold, it is determined that the alternating current power supply has a leakage. Through the above method, the problem that the leakage of the alternating current power supply causes hidden dangers to the personal safety of the user in the scene of applying the alternating current power supply is solved.

Description

Technical Field

[0001] This application relates to the technical field of leakage current detection, and in particular to a method, circuit, and on-board charger for detecting leakage current in AC power supplies. Background Technology

[0002] The on-board charger is an important component of an electric vehicle, and it typically has an AC port and a high-voltage DC port.

[0003] When the on-board charger is charging, it needs to connect to the power grid to charge the battery. At this time, the AC port serves as the input port, connecting to the AC power supply in the grid; the high-voltage port is the output port of the on-board charger, used to connect to a high-voltage DC load. In situations where AC power is used, there are often scenarios where the user and the aforementioned high-voltage equipment are in the same space. If leakage occurs when using AC power, it will pose a serious threat to the user's personal safety.

[0004] Currently, there is an urgent need for a leakage current detection circuit, method, and on-board charger for AC power supplies to solve the problems existing in related technologies. Summary of the Invention

[0005] This application provides a leakage current detection circuit, method, and on-board charger for AC power supply, which can detect leakage current in AC power supply in a timely manner in scenarios where AC power supply is used, thereby protecting the personal safety of users.

[0006] The first aspect of this application provides a leakage current detection circuit for an AC power supply. The circuit includes: an AC power supply, an impedance adjustment module, a first sampling module, a second sampling module, a power converter, a sampling signal processing module, a comparison module, and an equivalent leakage resistance. The first sampling module includes a first sampling point, and the second sampling module includes a second sampling point. The AC power supply and the impedance adjustment module are connected in parallel. One end of the AC power supply is coupled to one end of the first sampling module, and the other end of the AC power supply is coupled to one end of the second sampling module. The impedance adjustment module is coupled to both the first and second sampling modules. The other end of the first sampling module is coupled to the other end of the second sampling module. The signal receiving end of the sampling signal processing module is coupled to both the first and second sampling points. The comparison module is coupled to the signal output end of the sampling signal processing module. The equivalent leakage resistance is connected in parallel with either the first or second sampling module.

[0007] By employing the circuit described above, this application can promptly detect leakage current in AC power supply by acquiring and comparing signals from two sampling points when using AC power.

[0008] In one possible implementation, the first sampling module includes a first impedance element and a second impedance element, and the second sampling module includes a third impedance element and a fourth impedance element. The impedance elements are composed of any one or more electronic devices including resistors, capacitors, and inductors. One end of the first impedance is coupled to one end of the AC power supply, and the other end of the first impedance is coupled to one end of the second impedance element. The other end of the second impedance element is coupled to one end of the fourth impedance element. The other end of the fourth impedance element is coupled to one end of the third impedance element. The other end of the third impedance element is coupled to the other end of the AC power supply.

[0009] This application provides a topology for a sampling module by employing the above-described circuit, and in practical applications, it enables the configuration of different types of impedance elements.

[0010] In one possible implementation, the first impedance element and the third impedance element have the same element characteristics, and the second impedance element and the fourth impedance element have the same element characteristics; the element characteristics include the type of electronic device constituting the impedance element, the parameters of the electronic device, and the topology.

[0011] By employing the circuit described above, this application ensures that the first and third impedance elements have the same characteristics, and the second and fourth impedance elements have the same element characteristics. This makes it easier to obtain the effective voltage values ​​of the two sampling points in the subsequent acquisition of the effective voltage values, and to make a judgment based on the deviation between the effective voltage values ​​of the two sampling points.

[0012] In one possible implementation, the first sampling point is the coupling point between the first impedance element and the second impedance element, and the second sampling point is the coupling point between the fourth impedance element and the third impedance element.

[0013] This application uses the above circuit to determine the position of the sampling point in each impedance element, ensuring that the effective voltage value obtained from each sampling point and the deviation between the effective voltage values ​​of two sampling points can properly reflect the leakage of the AC power supply.

[0014] A second aspect of this application provides a method for detecting AC power leakage. The method includes: in response to a user's power-on action on the AC power supply, acquiring a first sampling signal, the first sampling signal including a sampling signal at a first sampling point and a sampling signal at a second sampling point; performing impedance matching and hardware filtering on the first sampling signal to obtain a second sampling signal; performing software filtering on the second sampling signal to obtain a third sampling signal, the third sampling signal including the effective voltage value and peak voltage value at the first sampling point and the effective voltage value and peak voltage value at the second sampling point; and confirming that AC power leakage has occurred when the deviation between the effective voltage value at the first sampling point and the effective voltage value at the second sampling point is greater than or equal to a preset voltage deviation threshold.

[0015] By employing the above method, this application acquires and compares signals from two sampling points when using AC power, enabling timely detection of any leakage current when AC power is applied.

[0016] In one possible implementation, when the equivalent leakage resistance is connected in parallel with the second sampling module, the effective voltage values ​​of the first sampling point and the second sampling point are determined according to the following formula: ΔU=|U Z0Z1 -U Z2Z3 |;Among them, U Z0Z1 U represents the effective voltage value of the first and second impedance elements. Z2Z3 U1 represents the effective voltage value of the third and fourth impedance elements, U2 represents the effective voltage value of the first sampling point, U2 represents the effective voltage value of the second sampling point, and ΔU represents the deviation. AC Z0 is the effective value of the output voltage of the AC power supply; Z1 is the equivalent impedance of the first impedance element; Z2 is the equivalent impedance of the fourth impedance element; Z3 is the equivalent impedance of the third impedance element; Z4 is the effective value of the output voltage of the AC power supply; Z5 is the equivalent impedance of the first impedance element; Z6 is the equivalent iso This is the equivalent leakage resistance.

[0017] This application provides a method for obtaining the effective voltage value of each sampling point by employing the above-described method. This allows the circuit using this method to obtain the effective voltage value of each sampling point not only through processing the sampled signal, but also by using the above formula to obtain the effective voltage value of each sampling point based on the parameters of each impedance element. Furthermore, this method for obtaining the effective voltage value can also be used to verify the effective voltage values ​​of the sampling points obtained by the sampling signal processing module and the comparison module.

[0018] In one possible implementation, when the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point is less than a preset voltage deviation threshold, it is confirmed that the insulation of the AC power supply is normal and no leakage has occurred.

[0019] This application, by employing the above method, detects the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point when using AC power, and also determines whether the insulation condition of the AC power supply is normal.

[0020] In one possible implementation, when the effective voltage value of the first sampling point and the effective voltage value of the second sampling point satisfy the following formula... UZ0Z1 =U Z2Z3 =0.5U AC , Confirm that the insulation of the AC power supply is normal; Among them, U Z0Z1 U represents the effective voltage value of the first and second impedance elements. Z2Z3 U1 represents the effective voltage value of the third and fourth impedance elements, U2 represents the effective voltage value of the first sampling point, and U3 represents the effective voltage value of the second sampling point. AC Z0 represents the effective value of the output voltage of the AC power supply, Z1 represents the equivalent impedance of the first impedance element, Z2 represents the equivalent impedance of the fourth impedance element, Z3 represents the equivalent impedance of the third impedance element, and Z4 represents the equivalent leakage resistance. By employing the above method, this application can obtain the relationship between the effective voltage values ​​of the first and second sampling points when the AC power supply is under normal insulation conditions. This allows for a clearer assessment of the leakage current of the AC power supply based on the effective voltage values ​​at each sampling point.

[0021] In one possible implementation, when a leakage occurs in the AC power supply, the AC power supply is controlled to disconnect the switch.

[0022] By employing the above method, this application can control the AC power supply to disconnect when a leakage current is detected in the AC power supply, thereby further ensuring the personal safety of the user.

[0023] Compared with related technologies, the beneficial effects of this application are: when using AC power, by acquiring and comparing the signals of two sampling points, leakage can be detected in a timely manner. A topology for a sampling module is provided, which can be configured with different types of impedance elements in practical applications. By ensuring that the first and third impedance elements have the same characteristics, and the second and fourth impedance elements have the same element characteristics, it is easier to obtain the effective voltage values ​​of the sampling points and to judge the deviation between the effective voltage values ​​of the two sampling points in the subsequent acquisition of the effective voltage values ​​of the two sampling points. The position of the sampling point in each impedance element is determined to ensure that the effective voltage values ​​acquired at each sampling point and the deviation between the effective voltage values ​​of the two sampling points can correctly reflect the leakage of the AC power supply. A method for obtaining the effective voltage values ​​of each sampling point is given, so that in the circuit applying the above method, in addition to obtaining the effective voltage values ​​of each sampling point by processing the sampling signal, the effective voltage values ​​of each sampling point can also be obtained by using the above formula based on the parameters of each impedance element. Furthermore, the above method for obtaining the effective voltage values ​​can also be used to verify the effective voltage values ​​of the sampling points obtained by the sampling signal processing module and the comparison module. When using AC power, the deviation between the effective voltage values ​​at the first and second sampling points is detected to determine the insulation condition of the AC power supply. The relationship between the effective voltage values ​​at the first and second sampling points when the insulation is normal can be obtained, allowing for a clearer assessment of leakage current based on the effective voltage values ​​at each sampling point. Upon detecting leakage current in the AC power supply, the system can control the AC power supply to disconnect, further ensuring user safety. Attached Figure Description

[0024] Figure 1 This is a first structural schematic diagram of a leakage current detection circuit for an AC power supply provided in an embodiment of this application; Figure 2 This is a second structural schematic diagram of a leakage current detection circuit for an AC power supply provided in an embodiment of this application; Figure 3 This is a third structural schematic diagram of a leakage current detection circuit for an AC power supply provided in an embodiment of this application; Figure 4 This is a fourth structural schematic diagram of a leakage current detection circuit for an AC power supply provided in an embodiment of this application; Figure 5 This is a schematic flowchart of a leakage current detection method for AC power supply provided in an embodiment of this application.

[0025] Reference numerals: C1, first capacitor; C2, second capacitor; 10, AC power supply; 11, impedance adjustment module; 12, first sampling module; 121, first impedance element; 122, second impedance element; 13, second sampling module; 131, third impedance element; 132, fourth impedance element; 14, power converter; 15, sampling signal processing module; 16, comparison module; Z iso Equivalent leakage resistance. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0027] In the description of the embodiments of this application, words such as "illustrative," "for example," or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "illustrative," "for example," or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Rather, the use of words such as "illustrative," "for example," or "for example" is intended to present the relevant concepts in a specific manner.

[0028] In the description of the embodiments of this application, 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0029] The on-board charger in this embodiment can be used in various new energy electric vehicles. It features high-speed CAN network and BMS communication capabilities, enabling it to determine the correctness of the vehicle battery connection status. It can also obtain battery system parameters and real-time data for the entire battery pack and individual cells before and during charging. It can communicate with the vehicle monitoring system via the high-speed CAN network, uploading the charger's operating status, operating parameters, and fault alarm information, and receiving commands to start or stop charging. Furthermore, the on-board charger ensures that the voltage, temperature, and current of the individual power battery cells do not exceed permissible values ​​during charging.

[0030] In the embodiments of this application, such as Figure 1 As shown, the right side of the power converter 14 can be configured with corresponding output circuits or input circuits according to actual needs. This application embodiment does not make specific limitations on this.

[0031] like Figure 1 As shown, Figure 1 This application provides a leakage current detection circuit for an AC power supply. The circuit includes: an AC power supply 10, an impedance adjustment module 11, a first sampling module 12, a second sampling module 13, a power converter 14, a sampling signal processing module 15, a comparison module 16, and an equivalent leakage current resistance Z. iso The first sampling module includes a first sampling point, and the second sampling module includes a second sampling point; AC power supply 10 is connected in parallel with impedance adjustment module 11, one end of AC power supply 10 is coupled to one end of first sampling module 12, and the other end of AC power supply 10 is coupled to one end of second sampling module 13; impedance adjustment module 11 is coupled to first sampling module 12 and second sampling module 13; the other end of first sampling module 12 is coupled to the other end of second sampling module 13; power converter 14 is connected in parallel with AC power supply 10; the signal receiving end of sampling signal processing module 15 is coupled to the first sampling point and the second sampling point respectively; comparison module 16 is coupled to the signal output end of sampling signal processing module 15; equivalent leakage resistance Z iso It is connected in parallel with either the first sampling module 12 or the second sampling module 13.

[0032] In this embodiment, the AC power supply 10, the comparison module 16, and the sampling signal processing module can be grounded together or separately. This embodiment does not impose specific limitations on this.

[0033] Specifically, in the embodiments of this application, such as Figure 1 As shown, when the user supplies power to the on-board charger using AC power supply 10, the equivalent leakage resistance Z is... iso In an ideal scenario, the resistance can be considered infinite, equivalent to an open circuit. However, in practical AC power supply applications, an equivalent leakage resistance Z is unavoidable. iso And the equivalent leakage resistance Z iso The smaller the resistance value, the more severe the leakage current of the AC power supply 10. Based on this, the impedance adjustment module 11, in this circuit embodiment, incorporates a portion of the induced capacitance, considering the inherent capacitance effect between lines, into the error correction during leakage current detection. This allows for more accurate leakage current detection results. In this embodiment, the impedance adjustment module 11 is used to eliminate the initial leakage current value caused by the leakage phenomenon. This application does not elaborate on the specific circumstances leading to the leakage phenomenon; it is understood that the actual settings of the components in the impedance adjustment module 11 can be modified according to the specific circumstances causing the leakage phenomenon.

[0034] In this embodiment, the sampling signals from the sampling points of the first sampling module 12 and the second sampling module 13 are processed by the sampling signal processing module 15. The equivalent voltages of the two sampling points are then input to the comparison module 16. The deviation between the equivalent voltages of the two sampling points is compared with a preset deviation threshold to determine the leakage current of the AC power supply 10. In this embodiment, the power converter 14 is externally connected to a DC output circuit to provide DC power input. The DC output circuit will not be described in detail in this embodiment.

[0035] In one possible implementation, such as Figure 2 As shown, the first sampling module 12 includes a first impedance element 121 and a second impedance element 122, and the second sampling module 13 includes a third impedance element 131 and a fourth impedance element 132. The impedance elements are composed of any one or more electronic devices including resistors, capacitors, and inductors. One end of the first impedance 121 is coupled to one end of the AC power supply 10, and the other end of the first impedance 121 is coupled to one end of the second impedance element 122. The other end of the second impedance element 122 is coupled to one end of the fourth impedance element 132. The other end of the fourth impedance element 132 is coupled to one end of the third impedance element 131. The other end of the third impedance element 131 is coupled to the other end of the AC power supply 10.

[0036] In the embodiments of this application, the impedance element is composed of any one or more electronic devices including resistors, capacitors and inductors. For example, in the application of this application, a single impedance element can be composed of a resistor and a capacitor, and appropriate electronic devices can be reasonably selected according to the circuit parameter requirements and safety specifications.

[0037] In one possible implementation, the first impedance element 121 and the third impedance element 131 have the same element characteristics, and the second impedance element 122 and the fourth impedance element 132 have the same element characteristics; the element characteristics include the type of electronic device in the impedance element, the parameters of the electronic device, and the topology.

[0038] In one possible implementation, such as Figure 3 As shown, the impedance adjustment module 11 includes a first capacitor C1 and a second capacitor C2; one end of the first capacitor C1 is coupled to one end of the AC source 10, and the other end of the first capacitor C1 is coupled to one end of the second capacitor C2 and then grounded. The other end of the first capacitor C1 is also coupled to the other end of the second impedance element 122; the other end of the second capacitor C2 is coupled to the other end of the impedance adjustment module 11, and the other end of the second capacitor C2 is also coupled to one end of the fourth impedance element 132.

[0039] In one possible implementation, such as Figure 2As shown. The first sampling point is the coupling point between the first impedance element 121 and the second impedance element 122, and the second sampling point is the coupling point between the fourth impedance element 132 and the third impedance element 131.

[0040] Specifically, in the embodiments of this application, the circuit topology composed of the first impedance element 121, the second impedance element 122, the third impedance element 131, and the fourth impedance element 132 is symmetrical. Therefore, under ideal conditions, the equivalent leakage resistance Z iso When the impedance is infinitely large, the first sampling point is the coupling point between the first impedance element 121 and the second impedance element 122, and the second sampling point is the coupling point between the fourth impedance element 132 and the third impedance element 131. At this time, the effective voltage value of the first sampling point is the same as the effective voltage value of the second sampling point.

[0041] In one possible implementation, such as Figure 4 As shown, the first impedance element 121 and the third impedance element 131 are configured as capacitor-type elements; the second impedance element 122 and the fourth impedance element 132 are configured as resistor-type elements.

[0042] The circuit embodiments described in this application achieve the following beneficial effects: By employing the above circuit, when using AC power, leakage can be detected promptly by acquiring and comparing the signals from two sampling points. A topology for a sampling module is provided, and in practical applications, different types of impedance elements can be configured. By ensuring that the first and third impedance elements have the same characteristics, and the second and fourth impedance elements have the same element characteristics, it is easier to obtain the effective voltage values ​​of the two sampling points in the subsequent acquisition of the effective voltage values, and a judgment can be made based on the deviation between the effective voltage values ​​of the two sampling points.

[0043] like Figure 5 As shown, this application provides an AC source leakage current detection method, which is applied to, for example... Figure 2 , Figure 3 or Figure 4 The circuit shown includes steps S101-S104.

[0044] S101, in response to the user's power-on action on the AC power supply, acquire a first sampling signal, the first sampling signal including the sampling signal of the first sampling point and the sampling signal of the second sampling point.

[0045] S102, perform impedance matching and hardware filtering on the first sampled signal to obtain the second sampled signal.

[0046] Specifically, the sampling signal processing module 15 performs impedance matching and hardware filtering on the signals acquired from the first and second acquisition points. Impedance matching ensures that the sampled signal is transmitted to the sampling signal processing module 15 with minimal signal reflection back to the sampling point, thereby improving the success rate of signal transmission. Hardware filtering eliminates crosstalk interference generated during the transmission of the sampled signal. In this embodiment, low-pass, high-pass, or band-pass filters are selected to eliminate crosstalk interference based on the frequency distribution characteristics of the crosstalk interference and the sampling signal frequency.

[0047] S103, perform software filtering on the second sampled signal to obtain the third sampled signal. The third sampled signal includes the effective voltage value and peak voltage value of the first sampled point, as well as the effective voltage value and peak voltage value of the second sampled point.

[0048] In this embodiment, the comparison module 16 performs software filtering on the second sampled signal to obtain a third sampled signal. The third sampled signal includes the effective voltage value and peak voltage value of the first sampled point, as well as the effective voltage value and peak voltage value of the second sampled point.

[0049] In one possible implementation, when the deviation between the peak voltage of the first sampling point and the peak voltage of the second sampling point is greater than or equal to a preset peak deviation, it is confirmed that the AC power supply 10 has a leakage current.

[0050] Determining whether AC power supply 10 is leaking current by detecting the voltage peak values ​​at the first and second sampling points allows for a faster response to leakage and timely determination of the result. In this embodiment, when the deviation between the voltage peak values ​​at the first and second sampling points is less than a preset peak deviation, it is confirmed that the AC power supply 10 has normal insulation and no leakage has occurred.

[0051] S104, when the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point is greater than or equal to the preset voltage deviation threshold, it is confirmed that the AC power supply 10 has leakage.

[0052] In one possible implementation, when the equivalent leakage resistance is connected in parallel with the second sampling module 13, the effective voltage values ​​of the first sampling point and the second sampling point are determined according to the following formula: ΔU=|U Z0Z1 -U Z2Z3 |;Among them, U Z0Z1 U represents the effective voltage value of the first impedance element 121 and the second impedance element 122.Z2Z3 U1 is the effective voltage value of the third impedance element 131 and the fourth impedance element 132, U2 is the effective voltage value of the first sampling point, and U2 is the effective voltage value of the second sampling point. ΔU is the deviation. U AC Z0 is the effective value of the output voltage of AC power supply 10, Z1 is the equivalent impedance of the first impedance element 121, Z2 is the equivalent impedance of the second impedance element 122, Z3 is the equivalent impedance of the fourth impedance element 132, and Z4 is the equivalent impedance of the third impedance element 131. iso This is the equivalent leakage resistance.

[0053] In one possible implementation, the method further includes: when the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point is less than a preset voltage deviation threshold, confirming that the insulation of the AC power supply is normal and no leakage has occurred. The preset voltage deviation threshold in this embodiment can be set according to the circuit response accuracy required by the user, and will not be elaborated further in this embodiment.

[0054] In one possible implementation, the AC power supply is determined to be in good insulation condition when the effective voltage values ​​of the first sampling point and the second sampling point satisfy the following formula. U Z0Z1 =U Z2Z3 =0.5U AC , Among them, U Z0Z1 U represents the effective voltage value of the first impedance element 121 and the second impedance element 122. Z2Z3 U1 represents the effective voltage value of the third impedance element 131 and the fourth impedance element 132, U2 represents the effective voltage value of the first sampling point, and U3 represents the effective voltage value of the second sampling point. U AC Z0 is the effective value of the output voltage of AC power supply 10, Z1 is the equivalent impedance of the first impedance element 121, Z2 is the equivalent impedance of the second impedance element 122, Z3 is the equivalent impedance of the fourth impedance element 132, and Z4 is the equivalent impedance of the third impedance element 131, along with the equivalent leakage resistance. In one possible implementation, the method further includes: when leakage occurs in AC power supply 10, controlling AC power supply 10 to disconnect the switch.

[0055] This application provides an on-board charger, which includes any of the AC source detection circuits described in the above embodiments.

[0056] This application achieves the following beneficial effects through the above-described method embodiments: When using AC power, by acquiring and comparing signals from two sampling points, leakage can be detected promptly. A method for obtaining the effective voltage values ​​of each sampling point is provided, enabling the circuit using the above method to obtain the effective voltage values ​​of each sampling point not only through signal processing but also by using the above formula based on the parameters of each impedance element. Furthermore, this method for obtaining the effective voltage values ​​can also be used to verify the effective voltage values ​​of the sampling points obtained by the signal processing module and the comparison module. When using AC power, the deviation between the effective voltage values ​​of the first and second sampling points is detected, and the insulation condition of the AC power supply is assessed. The relationship between the effective voltage values ​​of the first and second sampling points when the AC power supply insulation is normal can be obtained, allowing for a clearer assessment of leakage based on the effective voltage values ​​of each sampling point. Upon detecting leakage in the AC power supply, the AC power supply can be switched off, further ensuring user safety.

[0057] It should be noted that the circuit and method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the circuit embodiments, which will not be repeated here.

[0058] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0059] 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.

[0060] The above description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of other embodiments of this disclosure upon considering the specification and the disclosure of practical truths. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described in this disclosure.

Claims

1. A leakage current detection circuit for an AC power supply, characterized in that, The circuit includes: an AC power supply (10), an impedance adjustment module (11), a first sampling module (12), a second sampling module (13), a power converter (14), a sampling signal processing module (15), a comparison module (16), and an equivalent leakage resistance (Z). iso The first sampling module includes a first sampling point, and the second sampling module includes a second sampling point; The AC power supply (10) is connected in parallel with the impedance adjustment module (11). One end of the AC power supply (10) is coupled to one end of the first sampling module (12), and the other end of the AC power supply (10) is coupled to one end of the second sampling module (13). The impedance adjustment module (11) is coupled to the first sampling module (12) and the second sampling module (13); The impedance adjustment module (11) includes a first capacitor (C1) and a second capacitor (C2); one end of the first capacitor (C1) is coupled to one end of the AC power supply (10), and the other end of the first capacitor (C1) is coupled to one end of the second capacitor (C2) and grounded; the other end of the first capacitor (C1) is also coupled to the other end of the second impedance element (122); the other end of the second capacitor (C2) is coupled to the other end of the impedance adjustment module (11), and the other end of the second capacitor (C2) is also coupled to one end of the fourth impedance element (132); The other end of the first sampling module (12) is coupled to the other end of the second sampling module (13); The power converter (14) is connected in parallel with the AC power supply (10); The signal receiving end of the sampling signal processing module (15) is coupled to the first sampling point and the second sampling point respectively; The comparison module (16) is coupled to the signal output terminal of the sampling signal processing module (15); The equivalent leakage resistance (Z) iso It is connected in parallel with any one of the first sampling module (12) or the second sampling module (13); The first sampling module (12) includes a first impedance element (121) and a second impedance element (122), and the second sampling module (13) includes a third impedance element (131) and a fourth impedance element (132). The impedance element is composed of any one or more electronic devices including resistors, capacitors and inductors. One end of the first impedance element (121) is coupled to one end of the AC power supply (10), and the other end of the first impedance element (121) is coupled to one end of the second impedance element (122); the other end of the second impedance element (122) is coupled to one end of the fourth impedance element (132); the other end of the fourth impedance element (132) is coupled to one end of the third impedance element (131); and the other end of the third impedance element (131) is coupled to the other end of the AC power supply (10). The first sampling point is the coupling point between the first impedance element (121) and the second impedance element (122), and the second sampling point is the coupling point between the fourth impedance element (132) and the third impedance element (131).

2. The leakage current detection circuit according to claim 1, characterized in that, The first impedance element (121) and the third impedance element (131) have the same element characteristics, and the second impedance element (122) and the fourth impedance element (132) have the same element characteristics. The characteristics of the components include the type of electronic device that makes up the impedance component, the parameters of the electronic device, and the topology.

3. A method for detecting leakage current in an AC power supply, wherein the method is applied to any one of the circuits in claims 1-2, characterized in that, The method includes: In response to the user's power-on action on the AC power supply (10), a first sampling signal is acquired, the first sampling signal including the sampling signal of the first sampling point and the sampling signal of the second sampling point; The first sampled signal is impedance matched and hardware filtered to obtain the second sampled signal; The second sampled signal is subjected to software filtering to obtain a third sampled signal, the third sampled signal including the effective voltage value and peak voltage value of the first sampled point and the effective voltage value and peak voltage value of the second sampled point; When the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point is greater than or equal to a preset voltage deviation threshold, it is confirmed that the AC power supply (10) has a leakage current.

4. The method according to claim 3, characterized in that, When the equivalent leakage resistance is connected in parallel with the second sampling module (13), the effective voltage value of the first sampling point and the effective voltage value of the second sampling point are determined according to the following formula: ； ； ； ； in, The effective voltage values ​​of the first impedance element (121) and the second impedance element (122) are given. The effective voltage values ​​of the third impedance element (131) and the fourth impedance element (132) are... The effective value of the voltage at the first sampling point. This represents the effective voltage value at the second sampling point. The deviation amount; The effective value of the output voltage of the AC power supply (10) is... The equivalent impedance of the first impedance element (121) is The equivalent impedance of the second impedance element (122) is The equivalent impedance of the fourth impedance element (132) is... The equivalent impedance of the third impedance element (131) is This is the equivalent leakage resistance.

5. The method according to claim 3, characterized in that, The method further includes: When the deviation between the effective voltage value of the first sampling point and the effective voltage value of the second sampling point is less than the preset voltage deviation threshold, it is confirmed that the insulation of the AC power supply (10) is normal and no leakage has occurred.

6. The method according to claim 4, characterized in that, The method further includes: When the effective voltage values ​​of the first sampling point and the second sampling point satisfy the following formula, it is determined that the AC power supply (10) is in good condition; ， ； ； in, The effective voltage values ​​of the first impedance element (121) and the second impedance element (122) are given. The effective voltage values ​​of the third impedance element (131) and the fourth impedance element (132) are given. The effective value of the voltage at the first sampling point. This is the effective voltage value at the second sampling point; The effective value of the output voltage of the AC power supply (10) is... The equivalent impedance of the first impedance element (121) is The equivalent impedance of the second impedance element (122) is The equivalent impedance of the fourth impedance element (132) is... The equivalent impedance of the third impedance element (131) is This is the equivalent leakage resistance.

7. The method of claim 3, wherein, The method further includes: When the AC power supply (10) leaks current, the AC power supply (10) is controlled to disconnect.

8. An on-board charger, characterized in that, The on-board charger includes the circuit described in any one of claims 1-2.

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