Leakage protection circuit and electric equipment

Abstract

The utility model relates to a leakage protection circuit and electric equipment. The electric leakage protection circuit comprises a first switch module, a second switch module, an electric leakage detection module and a voltage control module, electric equipment is connected with the voltage control module through the electric leakage detection module, the first switch module is arranged between the electric equipment and the electric leakage detection module, and the second switch module is arranged between the electric equipment and a voltage source; under the condition that the detection voltage output by the electric leakage detection module is smaller than a preset voltage threshold value, a high-level signal output by the voltage control module enables the first switch module to be disconnected; and when the detection voltage output by the electric leakage detection module is greater than or equal to a preset voltage threshold value, a low-level signal output by the voltage control module enables the second switch module to be disconnected. By adopting the leakage protection circuit, the safety of electric equipment can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of leakage detection, in particular to a leakage protection circuit and an electric device. BACKGROUND

[0002] Touch current refers to the current passing through the human body when the human body touches the accessible part of the electric device. This current can be caused by the working current, leakage current or other external factors inside the electric device.

[0003] Under normal circumstances, qualified electric devices should ensure that the touch current is below the safety limit to avoid harm to the human body. Therefore, there is an urgent need for a leakage protection circuit that can detect the touch current of the accessible part of the electric device to ensure the safety of the electric device. CONTENT OF THE INVENTION

[0004] Therefore, it is necessary to provide a leakage protection circuit and an electric device to ensure the safety of the electric device.

[0005] In a first aspect, the present application provides a leakage protection circuit, which comprises a first switch module, a second switch module, a leakage detection module and a voltage control module, the electric device is connected to the voltage control module through the leakage detection module, the first switch module is arranged between the electric device and the leakage detection module, and the second switch module is arranged between the electric device and a voltage source.

[0006] In the case where the detection voltage output by the leakage detection module is less than a preset voltage threshold, the high-level signal output by the voltage control module causes the first switch module to be disconnected.

[0007] In the case where the detection voltage output by the leakage detection module is greater than or equal to the preset voltage threshold, the low-level signal output by the voltage control module causes the second switch module to be disconnected.

[0008] In one of the embodiments, the leakage detection module comprises a current detection unit and an operational amplifier unit, the first end of the current detection unit is connected to the electric device, the second end of the current detection unit is connected to the first end of the operational amplifier unit, and the second end of the operational amplifier unit is connected to the input end of the voltage control module.

[0009] In one of the embodiments, the current detection unit comprises a filtering subunit and a current detection subunit, the first end of the filtering subunit is connected to the electric device, the second end of the filtering subunit is connected to the first end of the current detection subunit, and the second end of the current detection subunit is connected to the operational amplifier unit.

[0010] In one of the embodiments, the filtering subunit comprises a first resistor and a first capacitor connected in parallel, first ends of the first resistor and the first capacitor are connected with the electrical equipment, and second ends of the first resistor and the first capacitor are connected with the current detection subunit.

[0011] In one of the embodiments, the current detection subunit comprises a second resistor, a third resistor and a second capacitor, the third resistor and the second capacitor are connected in series and connected with the second resistor in parallel, first ends of the second resistor and the third resistor are connected with the filtering subunit, a second end of the third resistor is connected with a first end of the second capacitor, and a second end of the second capacitor is connected with a second end of the first resistor.

[0012] In one of the embodiments, the operational amplification unit comprises a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an operational amplifier, the fourth resistor is arranged between a same-phase input end of the operational amplifier and one end of the current detection unit, the fifth resistor is arranged between an inverse-phase input end of the operational amplifier and one end of the current detection unit, a first end of the sixth resistor is connected with a reference voltage source, a second end of the sixth resistor is connected with the fourth resistor and the same-phase input end of the operational amplifier, a first end of the seventh resistor is connected with the fifth resistor and the inverse-phase input end of the operational amplifier, and a second end of the seventh resistor is connected with an output end of the operational amplifier.

[0013] In one of the embodiments, the first switch module comprises a switch tube unit and an isolation switch, a first end of the switch tube unit is connected with the voltage control module, a second end of the switch tube unit is connected with a first end of the isolation switch, and a second end of the isolation switch is connected with the electric leakage detection module.

[0014] In one of the embodiments, the switch tube unit comprises an eighth resistor, a ninth resistor and a triode, a first end of the eighth resistor is connected with the voltage control module, a second end of the eighth resistor is connected with a base of the triode and a first end of the ninth resistor, a collector of the triode is connected with the isolation switch, and a second end of the ninth resistor and an emitter of the triode are grounded.

[0015] In one of the embodiments, the isolation switch comprises a relay, a first end of the relay is connected with the electric leakage detection module, a second end of the relay is connected with the power supply voltage, a third end of the relay is connected with the switch tube unit, and a fourth end of the relay is grounded.

[0016] In the second aspect, the application further provides an electrical equipment, which comprises the content of any one of the embodiments of the electric leakage protection circuit in the first aspect.

[0017] The leakage protection circuit and the electric device, the leakage protection circuit comprises: a first switch module, a second switch module, a leakage detection module and a voltage control module, the electric device is connected with the voltage control module through the leakage detection module, the first switch module is arranged between the electric device and the leakage detection module, and the second switch module is arranged between the electric device and a voltage source; in the case that the detection voltage output by the leakage detection module is less than a preset voltage threshold, the high-level signal output by the voltage control module makes the first switch module disconnected; in the case that the detection voltage output by the leakage detection module is greater than or equal to the preset voltage threshold, the low-level signal output by the voltage control module makes the second switch module disconnected. The voltage of the electric device is detected, and based on the comparison result of the detection voltage and the preset voltage threshold, the high-low level signal is output to control the disconnection of the two switch modules. In the case that the detection voltage is small, the connection between the electric device and the leakage detection module is disconnected, so that the electric device normally works under the power supply of the voltage source. In the case that the detection voltage is large, the connection between the electric device and the voltage source can be disconnected in time, so that when the human body contacts the accessible part of the electric device, no safety hazard occurs, and the safety of the electric device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the description of the embodiments of the present application or the related art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0019] Figure 1 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0020] Figure 2 It is a schematic diagram of the application scene of the leakage protection circuit in an embodiment;

[0021] Figure 3 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0022] Figure 4 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0023] Figure 5 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0024] Figure 6 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0025] Figure 7 It is a schematic diagram of the leakage protection circuit in an embodiment;

[0026] Figure 8 a schematic diagram of a leakage protection circuit in an embodiment;

[0027] Figure 9 a schematic diagram of a leakage protection circuit in an embodiment;

[0028] Figure 10 a schematic diagram of a leakage protection circuit in an embodiment.

[0029] Explanation of reference signs:

[0030] 10: leakage protection circuit;

[0031] 11: first switch module;

[0032] 111: switch tube unit;

[0033] 12: second switch module;

[0034] 13: leakage detection module;

[0035] 131: current detection unit;

[0036] 1311: filtering subunit;

[0037] 1312: current detection subunit;

[0038] 132: operational amplification unit;

[0039] 14: voltage control module;

[0040] 20: electrical equipment;

[0041] 30: voltage source. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0043] In the description of the present application, the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0044] In the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected" and the like should be understood in a broad sense, for example, it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] In one embodiment, as shown in Figure 1 A leakage protection circuit 10 is provided, which comprises a first switch module 11, a second switch module 12, a leakage detection module 13 and a voltage control module 14. The electrical equipment 20 is connected with the voltage control module 14 through the leakage detection module 13. The first switch module 11 is arranged between the electrical equipment 20 and the leakage detection module 13. The second switch module 12 is arranged between the electrical equipment 20 and the voltage source 30.

[0046] In the case that the detection voltage Vb output by the leakage detection module 13 is less than the preset voltage threshold, the high level signal output by the voltage control module 14 makes the first switch module 11 disconnected.

[0047] In the case that the detection voltage Vb output by the leakage detection module 13 is greater than the preset voltage threshold, the low level signal output by the voltage control module 14 makes the second switch module 12 disconnected.

[0048] Taking the case that the voltage source 30 is the high voltage end and the electrical equipment 20 is the low voltage end as an example, Figure 2 The application scenario diagram of the leakage protection circuit 10 is shown in the figure. As can be seen from the figure, the high voltage end and the low voltage end are connected through the transformer and the parasitic capacitor, and the high voltage end can supply power to the low voltage end. During power supply, the high voltage end passes through the parasitic capacitor to the low voltage end, and then passes through the human body to the ground to form a loop. Assuming that the human body contacts the accessible part of the low voltage end (for example, the shell of the electrical equipment), and the contact current of the accessible part is too large, the human body will feel numb or electric shock danger.

[0049] The leakage protection circuit 10 is arranged between the low voltage end and the ground, and can be integrated with the electrical equipment 20, and is specially used for leakage detection and protection of the electrical equipment 20. At this time, the leakage protection circuit 10 can only protect the electrical equipment 20 from leakage, and cannot protect other electrical equipment 20 from leakage. Alternatively, the leakage protection circuit 10 can also be a separate device, which is connected with the electrical equipment 20 when leakage protection is needed for the electrical equipment 20. In this case, the leakage protection circuit 10 can protect multiple different types of electrical equipment 20 from leakage, and can widen the use range of leakage protection.

[0050] It should be noted that the leakage protection circuit 10 can be used for safety detection before the electrical equipment 20 leaves the factory, and can also be used for leakage protection during use of the electrical equipment 20. The embodiments of the present application do not limit the setting position and use scenario of the leakage protection circuit 10.

[0051] In the embodiments of the present application, the input end of the leakage detection module 13 in the leakage protection circuit 10 is connected with the electrical equipment 20. When the voltage source 30 supplies power to the electrical equipment 20, the leakage detection module 13 in the leakage protection circuit 10 can detect the voltage acting on the human body, that is, the detection voltage. The leakage detection module 13 can be composed of a voltage dividing resistor, an operational amplifier U and the like.

[0052] The output end of the leakage detection module 13 is connected with the input end of the voltage control module 14. When the detection voltage Vb output by the leakage detection module 13 is input to the voltage control module 14, the voltage control module 14 can determine whether the detection voltage is less than the preset voltage threshold value through internal electronic elements. When it is determined that the detection voltage is less than the preset voltage threshold value, it means that the voltage acting on the human body is small and does not cause a safety hazard to the human body. At this time, the voltage control module 14 can output a high-level signal to control the first switch module 11 arranged between the electrical equipment 20 and the leakage detection module 13 to be disconnected, that is, the contactable part of the electrical equipment 20 does not cause harm to the human body, and subsequent leakage protection of the electrical equipment 20 does not need to be continued.

[0053] When it is determined that the detection voltage is greater than or equal to the preset voltage threshold value, it means that the voltage acting on the human body is large and is likely to cause a safety hazard to the human body. At this time, the voltage control module 14 can output a low-level signal to control the second switch module 12 arranged between the electrical equipment 20 and the voltage source 30 to be disconnected, so that the voltage source 30 cannot continue to supply power to the electrical equipment 20, and the power supply of the electrical equipment 20 is cut off from the source, thereby ensuring the safety of the electrical equipment 20. The voltage control module 14 can be composed of a comparator and other electronic elements. The same-phase input end of the comparator inputs the detection voltage Vb output by the leakage detection module 13, and the reverse input end inputs the preset voltage threshold value. Through the comparison result of the comparator, a high-level signal or a low-level signal is output.

[0054] The first switch module 11 and the second switch module 12 described above can be realized by means of a switch tube, a mechanical switch or a switch chip, etc. It should be noted that the second switch module 12 arranged between the electrical equipment 20 and the voltage source 30 can be arranged on the side of the user equipment.

[0055] The leakage protection circuit 10 comprises a first switch module 11, a second switch module 12, a leakage detection module 13 and a voltage control module 14. The electrical equipment 20 is connected with the voltage control module 14 through the leakage detection module 13. The first switch module 11 is arranged between the electrical equipment 20 and the leakage detection module 13. The second switch module 12 is arranged between the electrical equipment 20 and the voltage source 30. In the case that the detection voltage Vb output by the leakage detection module 13 is less than the preset voltage threshold, the high-level signal output by the voltage control module 14 makes the first switch module 11 disconnected. In the case that the detection voltage Vb output by the leakage detection module 13 is greater than or equal to the preset voltage threshold, the low-level signal output by the voltage control module 14 makes the second switch module 12 disconnected. The voltage of the electrical equipment 20 is detected, and based on the comparison result of the detection voltage and the preset voltage threshold, the high-level and low-level signals are output to control the disconnection of the two switch modules. In the case that the detection voltage is small, the connection between the electrical equipment 20 and the leakage detection module 13 is disconnected, so that the electrical equipment 20 can normally work under the power supply of the voltage source 30. In the case that the detection voltage is large, the connection between the electrical equipment 20 and the voltage source 30 can be disconnected in time, so that when the human body contacts the accessible part of the electrical equipment 20, no safety hazard occurs, and the safety of the electrical equipment 20 is improved.

[0056] When the leakage detection module 13 detects the leakage of the electrical equipment 20, the voltage of the accessible part of the electrical equipment 20 is small. In order to facilitate the observation of the voltage, the voltage needs to be amplified. Based on this, in one embodiment, as shown in FIG. 1, the leakage detection module 13 comprises a current detection unit 131 and an operational amplification unit 132. The first end of the current detection unit 131 is connected with the electrical equipment 20. The second end of the current detection unit 131 is connected with the first end of the operational amplification unit 132. The second end of the operational amplification unit 132 is connected with the input end of the voltage control module 14. Figure 3

[0057] In the embodiment of the present application, the current detection unit 131 is arranged between the electrical equipment 20 and the operational amplification unit 132, which can directly detect the current of the accessible part of the electrical equipment 20 and convert the detection current into the initial detection voltage Va. The current detection unit 131 can comprise sampling resistance, capacitance and other electronic elements.

[0058] Further, the initial detection voltage Va is applied to the operational amplification unit 132, which can amplify the initial detection voltage Va to obtain the detection voltage Vb, which is convenient for subsequent analysis of the detection voltage Vb. The operational amplification unit 132 can comprise an operational amplifier U, an amplification resistance related to the amplification multiple and other electronic elements.

[0059] ​The leakage detection module 13 includes a current detection unit 131 and an operational amplification unit 132. The first end of the current detection unit 131 is connected with the electrical equipment 20, the second end of the current detection unit 131 is connected with the first end of the operational amplification unit 132, and the second end of the operational amplification unit 132 is connected with the input end of the voltage control module 14. In the leakage detection process, the contact current of the electrical equipment 20 is detected by the current detection unit 131, and the contact current is converted into a detection voltage Vb. On this basis, the detection unit is amplified by the operational amplification unit 132, so that the detection voltage Vb is increased, and the subsequent analysis of the detection voltage Vb is facilitated.

[0060] Next, the current detection unit 131 and the operational amplification unit 132 in the leakage detection module 13 are introduced respectively. First, the specific content of the current detection unit 131 is introduced through an embodiment, as shown in FIG. 2. Figure 4 As shown in FIG. 2, the current detection unit 131 includes a filtering subunit 1311 and a current detection subunit 1312. The first end of the filtering subunit 1311 is connected with the electrical equipment 20, the second end of the filtering subunit 1311 is connected with the first end of the current detection subunit 1312, and the second end of the current detection subunit 1312 is connected with the operational amplification unit 132.

[0061] In the embodiment of the present application, the current of the contactable part of the electrical equipment 20 can have noise signals, so the filtering subunit 1311 is arranged between the current detection subunit 1312 and the electrical equipment 20. When detecting the current of the contactable part of the electrical equipment 20, the filtering subunit 1311 in the current detection unit 131 is used to filter the current of the contactable part, and the filtered current enters the current detection subunit 1312 to obtain the detection current of the electrical equipment 20. Based on the electronic elements in the current detection subunit, the detection current is transmitted to the operational amplification unit 132 in the form of a detection voltage.

[0062] The filtering subunit 1311 can be a filter, or a circuit with filtering function composed of parallel resistance and capacitance. The current detection subunit 1312 can be composed of resistance, capacitance and other electronic elements. The internal circuit of the filtering subunit 1311 and the current detection subunit 1312 is not limited in the embodiment of the present application, as long as the filtering and current detection functions are realized.

[0063] The current detection unit 131 includes a filtering subunit 1311 and a current detection subunit 1312, a first end of the filtering subunit 1311 is connected with the electrical equipment 20, a second end of the filtering subunit 1311 is connected with a first end of the current detection subunit 1312, and a second end of the current detection subunit 1312 is connected with the operational amplifier unit 132. By arranging the filtering subunit 1311 in the current detection unit 131, the noise signal in the contact current of the electrical equipment 20 can be removed, and the interference of the noise signal on the current is avoided, so that the current detected by the electronic detection subunit is more accurate.

[0064] Next, the specific content of the filtering subunit 1311 is described through an embodiment. Figure 5 As shown in the figure, the filtering subunit 1311 includes a first resistor R1 and a first capacitor C1 connected in parallel with each other, a first end of the first resistor R1 and a first end of the first capacitor C1 are connected with the electrical equipment 20, and a second end of the first resistor R1 and a second end of the first capacitor C1 are connected with the current detection subunit 1312.

[0065] In the embodiment of the present application, the circuit with filtering function formed by the parallel connection of the first resistor R1 and the first capacitor C1 is a low-pass filter, which has a small impedance for low-frequency signals and a large impedance for high-frequency signals, that is, the high-frequency signals can be filtered, so that the low-frequency detection current passes through, so that the influence of the high-frequency noise signal on the detection current is avoided.

[0066] The filtering subunit 1311 includes a first resistor R1 and a first capacitor C1 connected in parallel with each other, a first end of the first resistor R1 and a first end of the first capacitor C1 are connected with the electrical equipment 20, and a second end of the first resistor R1 and a second end of the first capacitor C1 are connected with the current detection subunit 1312. The filtering subunit 1311 formed by the parallel connection of the first resistor R1 and the first capacitor C1 can filter the high-frequency noise signal in the contact current of the electrical equipment 20, and avoid the influence of the high-frequency noise signal on the detection current.

[0067] In an embodiment, as shown in the figure, Figure 6 The current detection subunit 1312 includes a second resistor R2, a third resistor R3 and a second capacitor C2, the third resistor R3 and the second capacitor C2 are connected in series and connected in parallel with the second resistor R2, a first end of the second resistor R2 and a first end of the third resistor R3 are connected with the filtering subunit 1311, a second end of the third resistor R3 is connected with a first end of the second capacitor C2, and a second end of the second capacitor C2 is connected with a second end of the first resistor R1.

[0068] In the embodiment of the present application, the second resistor R2 and the third resistor R3 in the current detection subunit 1312 are used to perform shunt processing on the filtered contact current. The voltage on the second capacitor C2 is the voltage input to the operational amplifier U. The voltage control module 14 outputs a high or low level signal based on the comparison result of the detection voltage of the leakage detection module 13 and the preset voltage threshold, which is essentially to judge the current flowing through the second resistor R2. That is, when the current flowing through the second resistor R2 is large, the low level signal output by the voltage control module 14 makes the second switch module 12 disconnected. When the current flowing through the second resistor R2 is small, the high level signal output by the voltage control module 14 makes the first switch module 11 disconnected. Wherein, the current flowing through the second resistor R2 can be represented as:

[0069]

[0070] The current detection subunit 1312 includes the second resistor R2, the third resistor R3 and the second capacitor C2, the third resistor R3 and the second capacitor C2 are connected in series and are connected in parallel with the second resistor R2, the first end of the second resistor R2 and the first end of the third resistor R3 are connected with the filtering subunit 1311, the second end of the third resistor R3 is connected with the first end of the second capacitor C2, and the second end of the second capacitor C2 is connected with the second end of the first resistor R1. The filtered current is detected by the current detection subunit 1312 composed of two resistors and one capacitor, and the detected current is converted into voltage and transmitted to the operational amplification unit 132, which is convenient for subsequent amplification processing of the voltage.

[0071] Next, the content of the operational amplification unit 132 in the leakage detection module 13 is introduced, as shown in the figure, Figure 7 The operational amplification unit 132 includes the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the operational amplifier U, the fourth resistor R4 is arranged between the same phase input end of the operational amplifier U and one end of the current detection unit 131, the fifth resistor R5 is arranged between the opposite phase input end of the operational amplifier U and one end of the current detection unit 131, the first end of the sixth resistor R6 is connected with the reference voltage source Vref, the second end of the sixth resistor R6 is connected with the fourth resistor R4 and the same phase input end of the operational amplifier U respectively, the first end of the seventh resistor R7 is connected with the fifth resistor R5 and the opposite phase input end of the operational amplifier U respectively, and the second end of the seventh resistor R7 is connected with the output end of the operational amplifier U.

[0072] The fourth resistor R4 and the fifth resistor R5 have the same resistance value, and the sixth resistor R6 and the seventh resistor R7 have the same resistance value. The input end of the operational amplifier U is connected to the two ends of the second capacitor C2, that is, the first end of the fourth resistor R4 is connected to the first end of the second capacitor C2, and the second end of the fourth resistor R4 is connected to the positive input end of the operational amplifier U; the first end of the fifth resistor R5 is connected to the second end of the second capacitor C2, and the second end of the fifth resistor R5 is connected to the negative input end of the operational amplifier U. By collecting the contact current of the electrical equipment 20, the voltage signal between the two ends of the second capacitor C2 can be obtained. The detection voltage output by the output end of the operational amplifier U can be represented as:

[0073]

[0074] The above operational amplification unit 132 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an operational amplifier U. The fourth resistor R4 is arranged between the same-phase input end of the operational amplifier U and one end of the current detection unit 131. The fifth resistor R5 is arranged between the inverse-phase input end of the operational amplifier U and one end of the current detection unit 131. The first end of the sixth resistor R6 is connected to the reference voltage source Vref, and the second end of the sixth resistor R6 is connected to the fourth resistor R4 and the same-phase input end of the operational amplifier U. The first end of the seventh resistor R7 is connected to the fifth resistor R5 and the inverse-phase input end of the operational amplifier U, and the second end of the seventh resistor R7 is connected to the output end of the operational amplifier U. In the current sampling process, the operational amplifier U can amplify the voltage corresponding to the contact current, and the amplification multiple is determined by the resistance values of the four resistors, so that the detection voltage can be synchronized with the preset voltage threshold.

[0075] In the case that the contact current of the electrical equipment 20 does not pose a threat to the human body, the first switch module 11 arranged between the electrical equipment 20 and the leakage detection module 13 is in a disconnected state, so that the connection between the electrical equipment 20 and the leakage detection module 13 is disconnected, avoiding the interference of the leakage protection circuit 10 on the normal working process of the electrical equipment 20. In an embodiment, as shown in FIG. 2, the above first switch module 11 includes a switch tube unit 111 and an isolation switch 112. The first end of the switch tube unit 111 is connected to the voltage control module 14, the second end of the switch tube unit 111 is connected to the first end of the isolation switch 112, and the second end of the isolation switch 112 is connected to the leakage detection module 13. Figure 8

[0076] ​In the embodiments of the present application, the switch tube unit 111 can include one switch tube, and can also include one switch tube and other electronic elements. In one case, the on-off states of the switch tube in the switch tube unit 111 and the isolation switch 112 can be the same. For example, when the switch tube in the switch tube unit 111 is turned on, the isolation switch 112 is turned on, and the connection between the electrical equipment 20 and the leakage detection module 13 is maintained; when the switch tube in the switch tube unit 111 is turned off, the isolation switch 112 is turned off, and the connection between the electrical equipment 20 and the leakage detection module 13 is turned off.

[0077] In another case, the on-off states of the switch tube in the switch tube unit 111 and the isolation switch 112 can be different. For example, when the switch tube in the switch tube unit 111 is turned on, the isolation switch 112 is turned off, and the connection between the electrical equipment 20 and the leakage detection module 13 is turned off; when the switch tube in the switch tube unit 111 is turned off, the isolation switch 112 is turned on, and the connection between the electrical equipment 20 and the leakage detection module 13 is maintained.

[0078] The first switch module 11 includes the switch tube unit 111 and the isolation switch 112. The first end of the switch tube unit 111 is connected with the voltage control module 14, the second end of the switch tube unit 111 is connected with the first end of the isolation switch 112, and the second end of the isolation switch 112 is connected with the leakage detection module 13. By arranging the switch tube unit 111 and the isolation switch 112 between the electrical equipment 20 and the leakage detection module 13, the switch tube unit 111 and the isolation switch 112 include two switches. By turning on and turning off the two switches, the connection between the electrical equipment 20 and the leakage detection module 13 can be timely cut off in the case of small leakage current.

[0079] In one embodiment, as shown in FIG. 2, the switch tube unit 111 includes the eighth resistor R8, the ninth resistor R9 and the triode Q. The first end of the eighth resistor R8 is connected with the voltage control module 14, the second end of the eighth resistor R8 is connected with the base of the triode Q and the first end of the ninth resistor R9 respectively, the collector of the triode Q is connected with the isolation switch 112, and the second end of the ninth resistor R9 and the emitter of the triode Q are grounded. Figure 9

[0080] In the embodiments of the present application, when the contact current of the electrical equipment 20 is small and the voltage control module 14 outputs a low-level signal, the collector voltage of the triode Q is less than the on-voltage of the PN junction, so that the triode Q is turned off. In this case, the isolation switch 112 is turned off, and the connection between the leakage protection circuit 10 and the electrical equipment 20 is turned off. At the same time, the second switch module 12 remains in the on state, and the voltage source 30 can normally supply power to the electrical equipment 20. ​

[0081] When the contact current of the electrical equipment 20 is large, a safety hazard can be caused, and when the voltage control module 14 outputs a high-level signal, the collector voltage of the transistor Q is greater than the emitter voltage, and the base voltage is higher than the emitter voltage, so that the transistor Q is turned on. In this case, the isolating switch 112 remains turned on, and the connection between the leakage protection circuit 10 and the electrical equipment 20 is maintained. At the same time, the second switch module 12 is in an off state, and the connection between the voltage source 30 and the electrical equipment 20 is switched, which can avoid the occurrence of a safety hazard.

[0082] The above-mentioned switch tube unit 111 includes an eighth resistor R8, a ninth resistor R9, and a transistor Q, the first end of the eighth resistor R8 is connected with the voltage control module 14, the second end of the eighth resistor R8 is connected with the base of the transistor Q and the first end of the ninth resistor R9 respectively, the collector of the transistor Q is connected with the isolating switch 112, and the second end of the ninth resistor R9 and the emitter of the transistor Q are grounded. By using the high and low level signals output by the voltage control module 14 and the turn-on and turn-off characteristics of the transistor Q, the turn-on and turn-off states of the switch tube unit 111 can be accurately controlled, so that the connection state between the electrical equipment 20 and the leakage detection module 13 can be accurately controlled.

[0083] Next, the specific content of the isolating switch 112 is introduced through an embodiment, as shown in Figure 10 The isolating switch 112 includes a relay KJ, the first end of the relay KJ is connected with the leakage detection module 13, the second end of the relay KJ is connected with the power supply voltage, the third end of the relay KJ is connected with the switch tube unit 111, and the fourth end of the relay KJ is grounded.

[0084] In the embodiment of the present application, the isolating switch 112 is taken as an example of the relay KJ, the four ports of the relay KJ are connected with the power supply voltage, the collector of the transistor Q, the resistor two and the ground wire respectively, and the turn-on and turn-off of the relay KJ mainly depend on the connection between the resistor two and the ground wire. When the voltage control module 14 outputs a low-level signal, the transistor Q is turned off, the connection between the resistor two and the ground wire is disconnected, and the relay KJ disconnects the connection between the electrical equipment 20 and the leakage detection module 13. When the voltage control module 14 outputs a high-level signal, the transistor Q is turned on, the connection between the resistor two and the ground wire is maintained, and the relay KJ is closed, so that the connection between the electrical equipment 20 and the leakage detection module 13 is maintained.

[0085] The isolation switch 112 includes a relay KJ, a first end of the relay KJ is connected with the leakage detection module 13, a second end of the relay KJ is connected with the power supply voltage, a third end of the relay KJ is connected with the switch tube unit 111, and a fourth end of the relay KJ is grounded. The relay KJ is arranged as the isolation switch 112 between the electric device 20 and the leakage detection module 13, which can realize the electrical isolation between the electric device 20 and the leakage protection circuit 10, and avoid the influence of the electric device 20 on the leakage protection circuit 10, so as to protect the leakage protection circuit 10.

[0086] The above embodiments are all introductions of the first switch module 11, and the second switch module 12 can also include the switch tube unit 111 composed of the transistor Q and the two resistors, and the isolation switch 112. Alternatively, the second switch module 12 can also be a mechanical switch, for example, the mechanical switch can be a button switch, a handle switch or a knob switch, etc.

[0087] In an exemplary embodiment, the application also provides an electric device 20, which includes the content of any one of the above embodiments of the leakage protection circuit 10. In this case, the leakage protection circuit 10 is arranged in the electric device 20, and can only protect the electric device 20 from leakage.

[0088] The above is a further detailed description of the embodiments of the application in combination with specific / preferred embodiments, and cannot be regarded as limitation of the specific implementation of the embodiments of the application. For ordinary skilled in the art to which the embodiments of the application belong, without departing from the concept of the embodiments of the application, they can make several alternatives or modifications to the described embodiments, and these alternatives or modifications shall be regarded as falling within the protection scope of the embodiments of the application. In the description of the specification, the description of the terms "an embodiment", "some embodiments", "preferred embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the embodiments of the application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In order to make the description brief, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they shall be regarded as the scope of the description.

[0089] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as there is no conflict, any combination of the technical features should be considered within the scope of the present application.

[0090] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

[0091] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A leakage current protection circuit (10), characterized in that, The leakage protection circuit (10) includes: a first switch module (11), a second switch module (12), a leakage detection module (13), and a voltage control module (14). The electrical device (20) is connected to the voltage control module (14) through the leakage detection module (13). The first switch module (11) is located between the electrical device (20) and the leakage detection module (13), and the second switch module (12) is located between the electrical device (20) and the voltage source (30). When the detection voltage (Vb) output by the leakage current detection module (13) is less than the preset voltage threshold, the high-level signal output by the voltage control module (14) causes the first switch module (11) to disconnect. When the detection voltage (Vb) output by the leakage current detection module (13) is greater than or equal to the preset voltage threshold, the low-level signal output by the voltage control module (14) causes the second switch module (12) to disconnect.

2. The circuit according to claim 1, characterized in that, The leakage current detection module (13) includes a current detection unit (131) and an operational amplifier unit (132). The first end of the current detection unit (131) is connected to the electrical equipment (20), the second end of the current detection unit (131) is connected to the first end of the operational amplifier unit (132), and the second end of the operational amplifier unit (132) is connected to the input end of the voltage control module (14).

3. The circuit according to claim 2, characterized in that, The current detection unit (131) includes a filter subunit (1311) and a current detection subunit (1312). The first end of the filter subunit (1311) is connected to the electrical equipment (20), the second end of the filter subunit (1311) is connected to the first end of the current detection subunit (1312), and the second end of the current detection subunit (1312) is connected to the operational amplifier unit (132).

4. The circuit according to claim 3, characterized in that, The filtering subunit (1311) includes a first resistor (R1) and a first capacitor (C1) connected in parallel. The first ends of the first resistor (R1) and the first capacitor (C1) are both connected to the electrical equipment (20), and the second ends of the first resistor (R1) and the first capacitor (C1) are both connected to the current detection subunit (1312).

5. The circuit according to claim 3, characterized in that, The current detection subunit (1312) includes a second resistor (R2), a third resistor (R3), and a second capacitor (C2). The third resistor (R3) and the second capacitor (C2) are connected in series and then in parallel with the second resistor (R2). The first end of the second resistor (R2) and the first end of the third resistor (R3) are both connected to the filter subunit (1311). The second end of the third resistor (R3) is connected to the first end of the second capacitor (C2), and the second end of the second capacitor (C2) is connected to the second end of the first resistor (R1).

6. The circuit according to any one of claims 2-5, characterized in that, The operational amplifier unit (132) includes a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), and an operational amplifier (U). The fourth resistor (R4) is disposed between the non-inverting input terminal of the operational amplifier (U) and one end of the current detection unit (131). The fifth resistor (R5) is disposed between the inverting input terminal of the operational amplifier (U) and one end of the current detection unit (131). The first end of the sixth resistor (R6) is connected to the reference voltage source (30). The second end of the sixth resistor (R6) is connected to the fourth resistor (R4) and the non-inverting input terminal of the operational amplifier (U). The first end of the seventh resistor (R7) is connected to the fifth resistor (R5) and the inverting input terminal of the operational amplifier (U). The second end of the seventh resistor (R7) is connected to the output terminal of the operational amplifier (U).

7. The circuit according to any one of claims 1-5, characterized in that, The first switch module (11) includes a switch tube unit (111) and a disconnect switch (112). The first end of the switch tube unit (111) is connected to the voltage control module (14), the second end of the switch tube unit (111) is connected to the first end of the disconnect switch (112), and the second end of the disconnect switch (112) is connected to the leakage current detection module (13).

8. The circuit according to claim 7, characterized in that, The switching transistor unit (111) includes an eighth resistor (R8), a ninth resistor (R9), and a transistor (Q). The first end of the eighth resistor (R8) is connected to the voltage control module (14), and the second end of the eighth resistor (R8) is connected to the base of the transistor (Q) and the first end of the ninth resistor (R9). The collector of the transistor (Q) is connected to the disconnect switch (112), and the second end of the ninth resistor (R9) and the emitter of the transistor (Q) are both grounded.

9. The circuit according to claim 7, characterized in that, The disconnect switch (112) includes a relay (KJ), the first end of which is connected to the leakage current detection module (13), the second end of which is connected to the power supply voltage, the third end of which is connected to the switch tube unit (111), and the fourth end of which is grounded.

10. An electrical appliance (20), characterized in that, The electrical equipment (20) includes the leakage protection circuit (10) as described in any one of claims 1-9.

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