CN216560832U

CN216560832U - Grounding detection circuit and electric appliance

Info

Publication number: CN216560832U
Application number: CN202122663112.3U
Authority: CN
Inventors: 何峰
Original assignee: Shenzhen Angel Drinking Water Equipment Co Ltd
Current assignee: Shenzhen Angel Drinking Water Equipment Co Ltd
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2022-05-17
Anticipated expiration: 2031-11-02

Abstract

The application discloses ground connection detection circuitry and electrical apparatus belongs to circuit technical field. The grounding detection circuit comprises a detection module, a switch module, a controller and a grounding indication module. When the grounding detection circuit works, the controller controls the switch module to be conducted. At the moment, the detection module detects the current between the live wire and the ground wire and outputs a detection signal to the controller according to the current between the live wire and the ground wire. A preset range is set in the controller for the detection signal. Therefore, when the current between the live wire and the ground wire meets the grounding performance requirement of the electric appliance, the detection signal is in the preset range by adjusting the end value of the preset range. The controller controls the grounding indication module to work when the detection signal is within a preset range, so that the effects of detecting and indicating the grounding performance of the electric appliance are achieved.

Description

Grounding detection circuit and electric appliance

Technical Field

The application relates to the technical field of circuits, in particular to a grounding detection circuit and an electric appliance.

Background

When an electrical appliance with high power is connected with a mains supply, the electrical appliance is generally required to be respectively connected with a live wire, a zero line and a ground wire of the mains supply. Therefore, when the electric appliance leaks electricity, the leakage current can directly flow into the ground wire, so that the electric shock of a human body contacting with the electric appliance is avoided. However, the mains supply provided by many buildings has a ground fault, and in this case, after the electric appliance is connected with the mains supply, the electric appliance cannot be connected to the ground wire, so that a great potential safety hazard exists. Therefore, a circuit for detecting the grounding performance of an electrical appliance is urgently needed.

SUMMERY OF THE UTILITY MODEL

The application provides a ground connection detection circuit and electrical apparatus, can detect the ground connection performance of electrical apparatus. The technical scheme is as follows:

in a first aspect, a ground fault detection circuit is provided, including: the device comprises a detection module, a switch module, a controller and a grounding indication module;

the first end of the detection module is used for being connected with a live wire, the second end of the detection module is connected with the first end of the switch module, and the second end of the switch module is used for being connected with a ground wire, so that when the switch module is switched on, the detection module outputs a detection signal according to the current between the live wire and the ground wire;

a first output end of the controller is connected with a control end of the switch module so as to control the switch module to be conducted; the input end of the controller is connected with the output end of the detection module so as to input the detection signal; and a second output end of the controller is connected with the grounding indication module, and the controller controls the grounding indication module to work when the detection signal is within a preset range.

In the present application, the ground detection circuit includes a detection module, a switch module, a controller, and a ground indication module. When the grounding detection circuit works, the controller controls the switch module to be conducted. At the moment, the detection module detects the current between the live wire and the ground wire and outputs a detection signal to the controller according to the current between the live wire and the ground wire. A preset range is set in the controller for the detection signal. Therefore, the detection signal is in the preset range when the current between the live wire and the ground wire meets the grounding performance requirement of the electric appliance by adjusting the end value of the preset range; when the current between the live wire and the ground wire does not meet the grounding performance requirement of the electric appliance, the detection signal is out of the preset range. The controller controls the grounding indication module to work when the detection signal is within a preset range, so that the effects of detecting and indicating the grounding performance of the electric appliance are achieved.

Optionally, the detection module includes: the photoelectric coupler, the first resistor and the second resistor;

the first end of the photoelectric coupler is used for being connected with the live wire, and the second end of the photoelectric coupler is connected with the first end of the switch module;

the first end of the first resistor is used for being connected with a first voltage end, the second end of the first resistor is connected with the third end of the photoelectric coupler, and the fourth end of the photoelectric coupler is used for inputting zero voltage;

and the first end of the second resistor is connected with the second end of the first resistor, and the second end of the second resistor is connected with the input end of the controller so as to output the detection signal.

Optionally, the detection module includes: the transformer, the bridge rectifier and the third resistor;

the transformer comprises a primary coil and a secondary coil, wherein the first end of the primary coil is used for being connected with the live wire, and the second end of the primary coil is connected with the first end of the switch module;

the first end of the secondary side coil is connected with the first input end of the bridge rectifier, and the second end of the secondary side coil is connected with the second input end of the bridge rectifier;

a first output end of the bridge rectifier is connected with a first end of the third resistor, and a second end of the third resistor is connected with an input end of the controller so as to output the detection signal; and the second output end of the bridge rectifier is used for inputting zero voltage.

Optionally, the detection module further comprises: the capacitor, the voltage stabilizing diode and the fourth resistor;

the first polar plate of the capacitor is connected with the first output end of the bridge rectifier, and the second polar plate of the capacitor is connected with the second output end of the bridge rectifier;

the cathode of the voltage stabilizing diode is connected with the first output end of the bridge rectifier, and the anode of the voltage stabilizing diode is connected with the second output end of the bridge rectifier;

the first end of the fourth resistor is connected with the first output end of the bridge rectifier, and the second end of the fourth resistor is connected with the second output end of the bridge rectifier.

Optionally, the ground detection circuit further comprises: and a first end of the fifth resistor is used for being connected with the live wire, and a second end of the fifth resistor is connected with the first end of the detection module.

Optionally, the switch module comprises: the relay, the transistor, the sixth resistor and the seventh resistor;

the first end of the relay is connected with the second end of the detection module, and the second end of the relay is used for being connected with the ground wire;

the third end of the relay is used for being connected with a second voltage end, the fourth end of the relay is connected with the first pole of the transistor, the second pole of the transistor is used for inputting zero voltage, so that when the transistor is conducted, current passes between the third end and the fourth end of the relay, and the first end and the second end of the relay are conducted;

a first end of the sixth resistor is connected with the control electrode of the transistor, and a second end of the sixth resistor is connected with a first output end of the controller;

a first terminal of the seventh resistor is connected to the control electrode of the transistor, and a second terminal of the seventh resistor is connected to the second electrode of the transistor.

Optionally, the switch module further comprises: and the anode of the diode is connected with the fourth end of the relay, and the cathode of the diode is connected with the third end of the relay.

Optionally, the ground indication module includes one or more of an indicator light, a display screen, a vibrator, and a buzzer.

In a second aspect, a ground detection circuit is provided, comprising: the device comprises a detection module, a switch module, a controller and a grounding indication module;

the first end of the switch module is used for being connected with a live wire, the second end of the switch module is connected with the first end of the detection module, and the second end of the detection module is used for being connected with a ground wire, so that when the switch module is switched on, the detection module outputs a detection signal according to the current between the live wire and the ground wire;

a first output end of the controller is connected with a control end of the switch module so as to control the switch module to be conducted; the input end of the controller is connected with the output end of the detection module so as to input the detection signal; and a second output end of the controller is connected with the grounding indication module so that the controller controls the grounding indication module to work when the detection signal is within a preset range.

In a third aspect, an electrical appliance is provided, comprising the ground detection circuit as set forth in any one of the first and second aspects.

It is understood that, the beneficial effects of the second and third aspects may be referred to the relevant description of the first aspect, and are not described herein again.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a first ground fault detection circuit provided in an embodiment of the present application;

fig. 2 is a circuit configuration diagram of a first grounding detection circuit provided in an embodiment of the present application;

fig. 3 is a circuit configuration diagram of a second grounding detection circuit provided in an embodiment of the present application;

fig. 4 is a circuit configuration diagram of a third grounding detection circuit provided in the embodiment of the present application;

fig. 5 is a circuit configuration diagram of a fourth ground detection circuit provided in the embodiment of the present application;

fig. 6 is a schematic structural diagram of a second ground fault detection circuit provided in the embodiment of the present application.

Wherein, the meanings represented by the reference numerals of the figures are respectively as follows:

10. a ground detection circuit;

110. a detection module;

112. a bridge rectifier;

120. a switch module;

130. a controller;

140. and a grounding indication module.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

It should be understood that reference to "a plurality" in this application refers to two or more. In the description of the present application, "/" means "or" unless otherwise stated, for example, a/B may mean a or B; "and/or" herein is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, for the convenience of clearly describing the technical solutions of the present application, the terms "first", "second", and the like are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.

The ground fault detection circuit provided in the embodiments of the present application is explained in detail below.

Fig. 1 is a schematic structural diagram of a ground fault detection circuit 10 according to an embodiment of the present disclosure. The grounding detection circuit 10 can be applied to an electric appliance to detect the grounding performance of the electric appliance when the electric appliance is connected with the mains supply. As shown in fig. 1, the ground detection circuit 10 includes a detection module 110, a switch module 120, a controller 130, and a ground indication module 140.

The detection module 110 is configured to detect a current magnitude between a live line L (hereinafter, referred to as a live line L) of the utility power and a ground line PE (hereinafter, referred to as a ground line PE) of the utility power, and output a detection signal according to the current magnitude between the live line L and the ground line PE. The detection module 110 has a first end a, a second end b and an output end h. The first end a of the detection module 110 is configured to be connected to the live line L, and the second end b of the detection module 110 is configured to be connected to the ground line PE. In this way, when a path is formed between the live line L and the ground line PE, the detection module 110 may detect a current magnitude between the live line L and the ground line PE and generate a detection signal. The output terminal h of the detection module 110 is used for outputting a detection signal.

The switch module 120 is used to control whether a path is formed between the live line L and the ground line PE. The switch module 120 has a first terminal c, a second terminal d, and a control terminal f. The first end c of the switch module 120 is connected to the second end b of the detection module 110, and the second end d of the switch module 120 is used for connecting to the ground PE. That is, the second terminal b of the detection module 110 is connected to the ground line PE through the first terminal c and the second terminal d of the switch module 120. In this way, when the first terminal c and the second terminal d of the switch module 120 are connected, a path is formed between the live line L and the ground line PE. On the contrary, when the first terminal c and the second terminal d of the switch module 120 are disconnected, the live line L and the ground line PE are disconnected. The control terminal f of the switch module 120 is used for controlling whether the first terminal c and the second terminal d of the switch module 120 are conducted or not.

The controller 130 has a first output e, an input g and a second output j. The first output end e of the controller 130 is connected to the control end f of the switch module 120, and is used for controlling whether the switch module 120 is turned on or off, that is, controlling the connection and disconnection between the first end c and the second end d of the switch module 120. The input terminal g of the controller 130 is connected to the output terminal h of the detection module 110 to input the detection signal. Generally, a preset range is set for the detection signal within the controller 130. When the detection signal is within the preset range, it indicates that the current between the live line L and the ground line PE meets the grounding performance requirement of the electrical appliance, and at this time, the controller 130 controls the grounding indication module 140 to operate. When the detection signal is not within the preset range, it indicates that the current between the live line L and the ground line PE does not meet the grounding performance requirement of the electrical appliance, and at this time, the grounding indication module 140 does not operate. The end value of the preset range can be flexibly set according to the grounding requirement of the electric appliance.

Specifically, the operation process of the ground fault detection circuit 10 is as follows: when the electrical appliance applied to the ground fault detection circuit 10 is connected to the utility power, the controller 130 of the ground fault detection circuit 10 is powered on. At this time, the controller 130 controls the switch module 120 to be turned on, i.e., controls the switch module 120 to be turned on between the first terminal c and the second terminal d. After the switch module 120 is turned on, the detection module 110 detects a current between the live line L and the ground line PE, and outputs a detection signal to the controller 130 according to the current between the live line L and the ground line PE. After the controller 130 obtains the detection signal, the detection signal is compared with a preset range, and if the detection signal is within the preset range, the controller 130 controls the grounding indication module 140 to work to indicate that the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electric appliance; on the contrary, if the detection signal is outside the preset range, the grounding indication module 140 does not operate, so as to indicate that the current between the live line L and the ground line PE does not meet the grounding performance requirement of the electrical appliance. Therefore, the purpose of detecting and indicating the grounding performance of the electric appliance can be achieved.

In other embodiments, if the detection signal is outside the preset range, the controller 130 controls the ground indication module 140 to operate, so as to indicate that the current magnitude between the live line L and the ground line PE does not meet the ground performance requirement of the electrical appliance; if the detection signal is within the preset range, the grounding indication module 140 does not operate to indicate that the current between the live line L and the ground line PE meets the grounding performance requirement of the electrical appliance.

In some embodiments, the detection signal may be a voltage signal or a current signal. Generally, after the electrical appliance is connected to the mains supply and the controller 130 controls the switch module 120 to be turned on, the better the grounding performance of the electrical appliance is, the larger the current between the live wire L and the ground wire PE is; the poorer the grounding performance of the appliance, the smaller the current between the live line L and the ground line PE. In some specific embodiments, the detection module 110 can output a voltage signal according to the magnitude of the current between the power line L and the ground line PE. When the current between the live line L and the ground line PE is larger, the voltage signal output by the detection module 110 is also larger; when the current between the live line L and the ground line PE is smaller, the voltage signal output by the detection module 110 is smaller. Or, when the current between the live line L and the ground line PE is larger, the voltage signal output by the detection module 110 is smaller; when the current between the live line L and the ground line PE is smaller, the voltage signal output by the detection module 110 is larger. In some embodiments, the detection module 110 can output a current signal according to the magnitude of the current between the power line L and the ground line PE. When the current between the live line L and the ground line PE is larger, the larger the current signal output by the detection module 110 is; when the magnitude of the current between the live line L and the ground line PE is smaller, the current signal output by the detection module 110 is also smaller. Or, when the magnitude of the current between the live line L and the ground line PE is larger, the smaller the current signal output by the detection module 110 is; when the magnitude of the current between the live line L and the ground line PE is smaller, the current signal output by the detection module 110 is also larger.

Two specific implementations of the detection module 110 are explained in detail below with reference to the drawings.

In a first possible implementation manner, as shown in fig. 2, the detection module 110 includes a photo coupler U1, a first resistor R1, and a second resistor R2. The first end of the opto-coupler U1 is for connection with the live line L. That is, the first end of the photo coupler U1 constitutes the first end a of the detection module 110. A second terminal of the optocoupler U1 is connected to the first terminal c of the switch module 120. That is, the second end of the photo coupler U1 constitutes the second end b of the detection module 110. The first end of the first resistor R1 is used for being connected with a first voltage end V1, the second end of the first resistor R1 is connected with the third end of the photoelectric coupler U1, and the fourth end of the photoelectric coupler U1 is used for inputting zero voltage. The voltage at the first voltage terminal V1 is greater than zero voltage. A first terminal of the second resistor R2 is connected to a second terminal of the first resistor R1, and a second terminal of the second resistor R2 is connected to the input terminal g of the controller 130, so as to output a detection signal. That is, the second terminal of the second resistor R2 constitutes the output terminal h of the detection module 110.

Specifically, as shown in fig. 2, the optocoupler U1 generally includes a light emitting diode and a photodiode packaged together. When the light emitting diode emits light, the photosensitive diode is conducted; on the contrary, when the light emitting diode does not emit light, the photosensitive diode is turned off. In the embodiment of the present application, the anode of the light emitting diode is the first end of the photocoupler U1, and the cathode of the light emitting diode is the second end of the photocoupler U1. The anode of the photodiode is the third end of the photoelectric coupler U1, and the cathode of the photodiode is the fourth end of the photoelectric coupler U1.

The voltage of the first voltage terminal V1 may be, for example, 3.3V or 5V. The zero voltage may be provided by the ground GND internal to the controller 130. The ground PE of the mains belongs to an external ground, in distinction to the ground GND inside the controller 130. Thus, when the switch module 120 is turned on and the detection module 110 is operated, if the grounding performance of the electrical appliance is good, the current between the live wire L and the ground wire PE causes the first end and the second end of the photocoupler U1 to be turned on, the light emitting diode in the photocoupler U1 emits light, and the third end and the fourth end of the photocoupler U1 are turned on. At this time, the second end of the second resistor R2 outputs a low voltage signal. On the contrary, if the grounding performance of the electrical appliance is not good, the current between the live wire L and the ground wire PE cannot make the first end and the second end of the photoelectric coupler U1 conduct, the light emitting diode in the photoelectric coupler U1 does not emit light, and the third end and the fourth end of the photoelectric coupler U1 are turned off. At this time, the voltage signal output by the second terminal of the second resistor R2 is equal to the voltage of the first voltage terminal V1, i.e., the second terminal of the second resistor R2 outputs a high voltage signal. Therefore, the purpose that the detection module 110 outputs the detection signal according to the current between the live line L and the ground line PE can be achieved. In this embodiment, the voltage of the output detection signal is smaller as the magnitude of the current between the live line L and the ground line PE is larger, and the voltage of the output detection signal is larger as the magnitude of the current between the live line L and the ground line PE is smaller.

Further, as shown in fig. 3, the ground detection circuit 10 may further include a fifth resistor R5. The first terminal of the fifth resistor R5 is connected to the live line L, and the second terminal of the fifth resistor R5 is connected to the first terminal a of the detection module 110. The fifth resistor R5 is used as a current-limiting resistor, so that the third terminal and the fourth terminal of the photoelectric coupler U1 are prevented from being connected when the current between the live line L and the ground line PE is small. In the embodiment of the present application, the magnitude of the detection signal output by the detection module 110 may be adjusted by adjusting the resistance of the fifth resistor R5. When the grounding performance requirement of the electrical appliance to which the grounding detection circuit 10 is applied is high, the resistance value of the fifth resistor R5 may be set to be large. Conversely, if the grounding performance requirement of the electrical appliance applied by the grounding detection circuit 10 is low, the resistance value of the fifth resistor R5 may be set to be small. Generally, in order to protect the photocoupler U1, the resistance value of the fifth resistor R5 should be greater than or equal to 5K Ω (kilo ohms). When the electric appliance has the earth leakage protection threshold value, the resistance value of the fifth resistor R5 should satisfy: when the switch module 120 is turned on, the current between the live line L and the ground line PE is smaller than the leakage protection threshold of the electrical appliance, so as to avoid triggering the leakage protection function of the electrical appliance.

The ground detection circuit 10 may also include a capacitor C1. One pole plate of the capacitor C1 is connected with the second end of the second resistor R2, and the other pole plate of the capacitor C1 is connected with the fourth end of the photoelectric coupler U1 and used for inputting zero voltage. The capacitor C1 is a voltage stabilizing filter capacitor, which can improve the stability of the detection signal output by the detection module 110.

In a second possible implementation, as shown in fig. 4, the detection module 110 includes a transformer, a bridge rectifier 112, and a third resistor R3. The transformer comprises a primary coil and a secondary coil, and the first end of the primary coil is used for being connected with a live wire L. That is, the first end of the primary coil constitutes the first end a of the detection module 110. The second terminal of the primary winding is connected to the first terminal c of the switching module 120. That is, the second end of the primary coil constitutes the second end b of the detection module 110. A first terminal of the secondary winding is connected to a first input terminal of the bridge rectifier 112 and a second terminal of the secondary winding is connected to a second input terminal of the bridge rectifier 112. A first output terminal of the bridge rectifier 112 is connected to a first terminal of a third resistor R3. The second output of the bridge rectifier 112 is used for inputting zero voltage. A second terminal of the third resistor R3 is connected to the input terminal g of the controller 130 to output a detection signal. That is, the second terminal of the third resistor R3 constitutes the output terminal h of the detection module 110.

Specifically, as shown in fig. 4, the bridge rectifier 112 includes a second diode D2, a third diode D3, a fourth diode D4, and a fifth diode D5. The anode of the third diode D3 is connected to the first end of the secondary winding. That is, the anode of the third diode D3 constitutes a first input terminal of the bridge rectifier 112. The anode of the second diode D2 is connected to the second end of the secondary winding. That is, the anode of the second diode D2 constitutes the second input terminal of the bridge rectifier 112. The cathode of the second diode D2 is connected to the cathode of the third diode D3 and to the first terminal of the third resistor R3. That is, the cathode of the second diode D2 and the cathode of the third diode D3 are connected to form the first output terminal of the bridge rectifier 112. The cathode of the fourth diode D4 is connected to the anode of the second diode D2, and the cathode of the fifth diode D5 is connected to the anode of the third diode D3. An anode of the fourth diode D4 and an anode of the fifth diode D5 are connected and used to input a zero voltage. That is, the anode of the fourth diode D4 and the anode of the fifth diode D5 are connected to form the second output terminal of the bridge rectifier 112.

The zero voltage may be provided by the ground GND internal to the controller 130. The ground PE of the mains belongs to an external ground, in distinction to the ground GND inside the controller 130. In this way, when the switch module 120 is turned on and the detection module 110 is operated, the better the grounding performance of the electrical appliance is, the larger the voltage on the primary winding of the transformer is, the larger the voltage on the secondary winding is, and the larger the detection signal output by the detection module 110 through the third resistor R3 is. Conversely, if the grounding performance of the electrical appliance is worse, the voltage on the primary winding of the transformer is smaller, the voltage on the secondary winding is also smaller, and the detection signal output by the detection module 110 through the third resistor R3 is also smaller. Therefore, the purpose that the detection module 110 outputs the detection signal according to the current between the live line L and the ground line PE can be achieved. In this embodiment, the detection signal may be either a current signal or a voltage signal. The controller 130 controls the ground indicating module 140 according to the magnitude of the voltage signal or the current signal output by the third resistor R3.

Further, as shown in fig. 5, the ground detection circuit 10 may further include a fifth resistor R5. The first terminal of the fifth resistor R5 is connected to the live line L, and the second terminal of the fifth resistor R5 is connected to the first terminal a of the detection module 110. The fifth resistor R5 is used as a voltage dividing resistor to avoid the output voltage of the secondary winding of the transformer from being too high. In the embodiment of the present application, the magnitude of the detection signal output by the detection module 110 may be adjusted by adjusting the resistance of the fifth resistor R5. When the grounding performance requirement of the electrical appliance to which the grounding detection circuit 10 is applied is high, the resistance value of the fifth resistor R5 may be set to be large. Conversely, if the grounding performance requirement of the electrical appliance applied by the grounding detection circuit 10 is low, the resistance value of the fifth resistor R5 may be set to be small. Generally, the resistance value of the fifth resistor R5 should be greater than or equal to 5K Ω (kilo ohms). When the electric appliance has the earth leakage protection threshold value, the resistance value of the fifth resistor R5 should satisfy: when the switch module 120 is turned on, the current between the live line L and the ground line PE is smaller than the leakage protection threshold of the electrical appliance, so as to avoid triggering the leakage protection function of the electrical appliance.

In some embodiments, as shown in fig. 5, the detection module 110 may further include: a capacitor C2, a zener diode D6 and a fourth resistor R4. A first plate of the capacitor C2 is connected to a first output terminal of the bridge rectifier 112, and a second plate of the capacitor C2 is connected to a second output terminal of the bridge rectifier 112. The capacitor C2 is a voltage stabilizing filter capacitor, which can improve the stability of the output voltage of the bridge rectifier 112. The cathode of the zener diode D6 is connected to the first output terminal of the bridge rectifier 112, and the anode of the zener diode D6 is connected to the second output terminal of the bridge rectifier 112. A first terminal of the fourth resistor R4 is connected to the first output terminal of the bridge rectifier 112, and a second terminal of the fourth resistor R4 is connected to the second output terminal of the bridge rectifier 112.

The detailed implementation of the switch module 120 is explained in detail below with reference to the drawings.

As shown in fig. 2, the switch module 120 may include a relay J, a transistor M1, a sixth resistor R6, and a seventh resistor R7. The first end of the relay J is connected to the second end b of the detection module 110. That is, the first end of the relay J constitutes the first end c of the switch module 120. The second end of the relay J is used for connection with the ground line PE. That is, the second terminal of the relay J constitutes the second terminal d of the switch module 120. The third terminal of the relay J is used for being connected with the second voltage terminal V2, the fourth terminal of the relay J is connected with the first pole of the transistor M1, and the second pole of the transistor M1 is used for inputting zero voltage, so that when the transistor M1 is turned on, current passes between the third terminal and the fourth terminal of the relay J. When current passes through the third end and the fourth end of the relay J, the first end and the second end of the relay J are conducted. A first terminal of the sixth resistor R6 is connected to the control electrode of the transistor M1, and a second terminal of the sixth resistor R6 is connected to the first output terminal e of the controller 130. That is, the second terminal of the sixth resistor R6 constitutes the control terminal f of the switch module 120. A first terminal of the seventh resistor R7 is connected to the control terminal of the transistor M1, and a second terminal of the seventh resistor R7 is connected to the second terminal of the transistor M1.

Specifically, as shown in fig. 2, the relay J is composed of a coil and a contact group. The contact set includes two contacts. When the coil of the relay J is energized, a path is formed between the two contacts. Conversely, when the coil of the relay J is not energized, the two contacts are open. The coil of the relay J is connected between the second voltage terminal V2 and the first pole of the transistor M1. The transistor M1 may be a MOS (metal oxide semiconductor) field effect transistor or an NPN transistor. Taking the example where the transistor M1 is an NPN transistor, the base of the transistor is the control electrode of the transistor M1, the collector of the transistor is the first electrode of the transistor M1, and the emitter of the transistor is the second electrode of the transistor M1.

The voltage of the second voltage terminal V2 may be, for example, 12V. The zero voltage may be provided by the ground GND internal to the controller 130. The ground PE of the mains belongs to an external ground, in distinction to the ground GND inside the controller 130. Taking the transistor M1 (such as an NPN transistor or an N MOS transistor) that is turned on when the transistor M1 is at a high level and turned off when the transistor M is at a low level as an example, the transistor M1 is turned on when the first output terminal e of the controller 130 outputs a high level signal. At this time, a path is formed between the second voltage terminal V2 and the ground GND through the coil of the relay J and the transistor M1, and a current flows through the coil of the relay J, that is, a current flows between the third terminal and the fourth terminal of the relay J. At this time, a path is formed between two contacts of the relay J, that is, the first end and the second end of the relay J are conducted, and the switch module 120 is conducted.

Further, as shown in fig. 3 to 5, the switch module 120 further includes a first diode D1. The anode of the first diode D1 is connected to the fourth terminal of the relay J, and the cathode of the first diode D1 is connected to the third terminal of the relay J. Thus, under the condition that the transistor M1 is turned on, if the voltage of the second voltage terminal V2 is too large, the first diode D1 is broken down by the voltage of the second voltage terminal V2, so as to short-circuit the relay J, thereby achieving the purpose of protecting the relay J.

In some embodiments, when the ground detection circuit 10 is in operation, the controller 130 controls the conduction duration of the switch module 120 to be less than 0.1 second, so as to avoid triggering the leakage protection function of the electrical appliance. That is, if the controller 130 outputs the high level signal from the first output terminal e to control the switch module 120 to be turned on, the duration of the high level signal output from the first output terminal e of the controller 130 is less than 0.1 second, so as to avoid triggering the leakage protection function of the electrical appliance, and reduce the risk to the user when the ground fault detection circuit 10 operates. After the switch module 120 is turned off, the controller 130 may control the ground indication module 140 to stop working, or may control the ground indication module 140 to continue working according to the current between the live line L and the ground line PE when the switch module 120 is turned on.

In some embodiments, the ground indication module 140 includes one or more of an indicator light, a display screen, a vibrator, and a buzzer.

When the grounding indication module 140 is an indicator light, the controller 130 compares the detection signal with the preset range after obtaining the detection signal, and if the detection signal is within the preset range, the controller 130 controls the indicator light to emit light to indicate that the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electrical appliance. If the detection signal is out of the preset range, the indicator lamp does not emit light to indicate that the current between the live wire L and the ground wire PE does not meet the grounding performance requirement of the electric appliance.

When the ground indication module 140 is a display screen, the controller 130 compares the detection signal with a preset range after obtaining the detection signal, and if the detection signal is within the preset range, the controller 130 controls the display screen to work. At this time, the display screen can display the word of 'the electric appliance is grounded' and the like to indicate that the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electric appliance. If the detection signal is out of the preset range, the display screen does not work, or words such as 'electric appliance is not grounded' are displayed, so that the current between the live wire L and the ground wire PE can not meet the grounding performance requirement of the electric appliance.

When the grounding indication module 140 is a vibrator, the controller 130 compares the detection signal with a preset range after obtaining the detection signal, and if the detection signal is within the preset range, the controller 130 controls the vibrator to vibrate to indicate that the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electrical appliance. And if the detection signal is out of the preset range, the vibrator does not vibrate to indicate that the current between the live wire L and the ground wire PE does not meet the grounding performance requirement of the electric appliance.

When the grounding indication module 140 is a buzzer, the controller 130 compares the detection signal with a preset range after obtaining the detection signal, and if the detection signal is within the preset range, the controller 130 controls the buzzer to make a sound to indicate that the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electrical appliance. If the detection signal is out of the preset range, the buzzer does not make a sound to indicate that the current between the live wire L and the ground wire PE does not meet the grounding performance requirement of the electric appliance.

Fig. 6 is a schematic structural diagram of another ground fault detection circuit 10 according to an embodiment of the present disclosure. As shown in fig. 6, the ground fault detection circuit 10 includes a detection module 110, a switch module 120, a controller 130, and a ground fault indication module 140. The first end c of the switch module 120 is used for connecting with the live line L, and the second end d of the switch module 120 is connected with the first end a of the detection module 110. The second end b of the detection module 110 is configured to be connected to the ground line PE, so that when the switch module 120 is turned on, the detection module 110 outputs a detection signal according to a current between the live line L and the ground line PE. The first output terminal e of the controller 130 is connected to the control terminal f of the switch module 120 to control the switch module 120 to be turned on. The input terminal g of the controller 130 is connected to the output terminal h of the detection module 110 to input the detection signal. The second output j of the controller 130 is connected to the ground indication module 140, so that the controller 130 controls the ground indication module 140 to operate when the detection signal is within the preset range. The working process of the ground detection circuit 10 is the same as that of the embodiment shown in fig. 1, and is not described again.

In the embodiment of the present application, the ground detection circuit 10 includes a detection module 110, a switch module 120, a controller 130, and a ground indication module 140. When the ground detection circuit 10 is in operation, the controller 130 controls the switch module 120 to be turned on. At this time, the detection module 110 detects a current between the live line L and the ground line PE, and outputs a detection signal to the controller 130 according to the current between the live line L and the ground line PE. A preset range is set for the detection signal in the controller 130. Therefore, the detection signal is in the preset range when the current between the live wire L and the ground wire PE meets the grounding performance requirement of the electric appliance by adjusting the end value of the preset range; when the current between the live wire L and the ground wire PE does not meet the grounding performance requirement of the electric appliance, the detection signal is out of the preset range. When the detection signal is within the preset range, the controller 130 controls the operation of the grounding indication module 140, so as to achieve the effect of detecting and indicating the grounding performance of the electrical appliance.

The detection module 110 may include a photo coupler U1, a first resistor R1, and a second resistor R2. In this case, the ground detection circuit 10 may further include a fifth resistor R5. The first terminal of the fifth resistor R5 is connected to the live line L, and the second terminal of the fifth resistor R5 is connected to the first terminal a of the detection module 110. The fifth resistor R5 is used as a current-limiting resistor, so that the third terminal and the fourth terminal of the photoelectric coupler U1 can be prevented from being connected when the current between the live wire L and the ground wire PE is small. The ground detection circuit 10 may also include a capacitor C1. One pole plate of the capacitor C1 is connected with the second end of the second resistor R2, and the other pole plate of the capacitor C1 is connected with the fourth end of the photoelectric coupler U1 and used for inputting zero voltage. The capacitor C1 is a voltage stabilizing filter capacitor, which can improve the stability of the detection signal output by the detection module 110.

The detection module 110 may include a transformer, a bridge rectifier 112, and a third resistor R3. In this case, the ground detection circuit 10 may further include a fifth resistor R5. The first terminal of the fifth resistor R5 is connected to the live line L, and the second terminal of the fifth resistor R5 is connected to the first terminal a of the detection module 110. The fifth resistor R5 is used as a voltage dividing resistor to avoid the output voltage of the secondary winding of the transformer from being too high. The detection module 110 may further include a capacitor C2, and the capacitor C2 is a voltage stabilizing filter capacitor, which may improve the stability of the output voltage of the bridge rectifier 112.

The switch module 120 may include a relay J, a transistor M1, a sixth resistor R6, and a seventh resistor R7. In this case, the switch module 120 may further include a first diode D1. The anode of the first diode D1 is connected to the fourth terminal of the relay J, and the cathode of the first diode D1 is connected to the third terminal of the relay J. Thus, under the condition that the transistor M1 is turned on, if the voltage of the second voltage terminal V2 is too large, the first diode D1 is broken down by the voltage of the second voltage terminal V2, so as to short-circuit the relay J, thereby achieving the purpose of protecting the relay J.

The embodiment of the application also provides an electric appliance. The electric appliance can be a water dispenser, a refrigerator, an air conditioner, a washing machine and the like. The appliance includes a ground detection circuit 10 as in any of the embodiments described above.

Specifically, the ground fault detection circuit 10 includes: the detection module 110, the switch module 120, the controller 130, and the ground indication module 140. The first end a of the detection module 110 is used for being connected to the live wire L, the second end b of the detection module 110 is connected to the first end c of the switch module 120, and the second end d of the switch module 120 is used for being connected to the ground wire PE, so that when the switch module 120 is turned on, the detection module 110 outputs a detection signal according to the current between the live wire L and the ground wire PE. The first output terminal e of the controller 130 is connected to the control terminal f of the switch module 120 to control the switch module 120 to be turned on. The input terminal g of the controller 130 is connected to the output terminal h of the detection module 110 to input the detection signal. The second output j of the controller 130 is connected to the ground indication module 140, and the controller 130 controls the ground indication module 140 to operate when the detection signal is within the preset range.

In some embodiments, the detection module 110 includes: photocoupler U1, first resistance R1 and second resistance R2. The first end of the photocoupler U1 is used for being connected with the live line L, and the second end of the photocoupler U1 is connected with the first end c of the switch module 120. The first end of the first resistor R1 is used for being connected with a first voltage end V1, the second end of the first resistor R1 is connected with the third end of the photoelectric coupler U1, and the fourth end of the photoelectric coupler U1 is used for inputting zero voltage. A first terminal of the second resistor R2 is connected to a second terminal of the first resistor R1, and a second terminal of the second resistor R2 is connected to the input terminal g of the controller 130, so as to output a detection signal.

In some embodiments, the detection module 110 includes: a transformer, a bridge rectifier 112 and a third resistor R3. The transformer comprises a primary winding and a secondary winding, a first end of the primary winding is used for being connected with the live line L, and a second end of the primary winding is connected with the first end c of the switch module 120. A first end of the secondary winding is connected to a first input of the bridge rectifier 112 and a second end of the secondary winding is connected to a second input of the bridge rectifier 112. The first output terminal of the bridge rectifier 112 is connected to the first terminal of the third resistor R3, and the second terminal of the third resistor R3 is connected to the input terminal g of the controller 130, so as to output the detection signal. The second output of the bridge rectifier 112 is used for inputting zero voltage.

In some embodiments, the detection module 110 further comprises: a capacitor C2, a zener diode D6 and a fourth resistor R4. A first plate of the capacitor C2 is connected to a first output terminal of the bridge rectifier 112, and a second plate of the capacitor C2 is connected to a second output terminal of the bridge rectifier 112. The cathode of the zener diode D6 is connected to the first output terminal of the bridge rectifier 112, and the anode of the zener diode D6 is connected to the second output terminal of the bridge rectifier 112. A first terminal of the fourth resistor R4 is connected to the first output terminal of the bridge rectifier 112, and a second terminal of the fourth resistor R4 is connected to the second output terminal of the bridge rectifier 112.

In some embodiments, the ground detection circuit 10 further comprises: and a first end of the fifth resistor R5, a first end of the fifth resistor R5 is used for being connected with the live line L, and a second end of the fifth resistor R5 is connected with the first end a of the detection module 110.

In some embodiments, the switch module 120 includes: relay J, transistor M1, sixth resistor R6, and seventh resistor R7. The first end of the relay J is connected to the second end b of the detection module 110, and the second end of the relay J is used for being connected to the ground PE. The third terminal of relay J is used for being connected with second voltage end V2, and the fourth terminal of relay J is connected with the first utmost point of transistor M1, and the second utmost point of transistor M1 is used for inputing zero voltage to when transistor M1 switches on, have electric current to pass through between the third terminal and the fourth terminal of relay J, switch on between the first terminal and the second terminal of relay J. A first terminal of the sixth resistor R6 is connected to the control electrode of the transistor M1, and a second terminal of the sixth resistor R6 is connected to the first output terminal e of the controller 130. A first terminal of the seventh resistor R7 is connected to the control terminal of the transistor M1, and a second terminal of the seventh resistor R7 is connected to the second terminal of the transistor M1.

In some embodiments, the switch module 120 further comprises: and the anode of the first diode D1 is connected with the fourth end of the relay J, and the cathode of the first diode D1 is connected with the third end of the relay J.

In some embodiments, the ground detection circuit 10 includes: the detection module 110, the switch module 120, the controller 130, and the ground indication module 140. The first end c of the switch module 120 is used for being connected to the live wire L, the second end d of the switch module 120 is connected to the first end a of the detection module 110, and the second end b of the detection module 110 is used for being connected to the ground wire PE, so that when the switch module 120 is turned on, the detection module 110 outputs a detection signal according to the current between the live wire L and the ground wire PE. The first output terminal e of the controller 130 is connected to the control terminal f of the switch module 120 to control the switch module 120 to be turned on. The input terminal g of the controller 130 is connected to the output terminal h of the detection module 110 to input the detection signal. The second output j of the controller 130 is connected to the ground indication module 140, so that the controller 130 controls the ground indication module 140 to operate when the detection signal is within the preset range.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A ground detection circuit, comprising: the device comprises a detection module, a switch module, a controller and a grounding indication module;

2. The ground detection circuit of claim 1, wherein the detection module comprises: the circuit comprises a photoelectric coupler, a first resistor and a second resistor;

3. The ground detection circuit of claim 1, wherein the detection module comprises: the transformer, the bridge rectifier and the third resistor;

4. The ground detection circuit of claim 3, wherein the detection module further comprises: the capacitor, the voltage stabilizing diode and the fourth resistor;

5. The ground detection circuit of any one of claims 1-4, further comprising: and a first end of the fifth resistor is used for being connected with the live wire, and a second end of the fifth resistor is connected with the first end of the detection module.

6. The ground detection circuit of any one of claims 1-4, wherein the switch module comprises: the relay, the transistor, the sixth resistor and the seventh resistor;

7. The ground detection circuit of claim 6, wherein the switch module further comprises: and the anode of the diode is connected with the fourth end of the relay, and the cathode of the diode is connected with the third end of the relay.

8. The ground detection circuit of any one of claims 1-4, wherein the ground indication module comprises one or more of an indicator light, a display screen, a vibrator, and a buzzer.

9. A ground detection circuit, comprising: the device comprises a detection module, a switch module, a controller and a grounding indication module;

10. An electrical appliance comprising a ground detection circuit as claimed in any one of claims 1 to 9.