Water heater protection circuit and protection method

Abstract

The invention belongs to the field of intelligent household appliances, and particularly relates to a water heater protection circuit and a protection method. The water heater protection circuit comprises a grounding detection circuit; the grounding detection circuit comprises a ground wire detection circuit, an optocoupler control circuit, a master control MCU and a grounding indicating lamp. The ground wire detection circuit is respectively connected with the live wire and the ground wire, the optocoupler control circuit is respectively connected with the ground wire detection circuit and the main control MCU, and the main control MCU is further connected with the grounding indicator lamp; the ground wire detection circuit is used for generating current in a positive period of alternating current when a live wire and a ground wire of the alternating current are well connected; the optocoupler control circuit is used for generating a square wave signal under the action of the current and sending the square wave signal to the main control MCU; and the main control MCU is used for confirming good access of the live wire and the ground wire according to the square wave signal and controlling the grounding indicating lamp to indicate normally.

Description

Technical Field

[0001] The invention belongs to the field of intelligent household appliances, and in particular relates to a water heater protection circuit and a protection method. Background Art

[0002] Electric water heaters use heating wires to convert electrical energy into thermal energy, and then heat cold water into hot water through heat conduction. Because electric water heaters can heat hot water instantly, their power is generally high. Once an electric water heater leaks electricity, it poses a major safety hazard.

[0003] In the prior art, the safety of water heaters is mainly ensured by means of safety grounding to protect against leakage, installing relays to ensure safe power off, and setting over-temperature protection to prevent the water heater from drying out.

[0004] However, the existing technology can only protect the safety of the neutral wire and the live wire when there is leakage, but cannot protect the safety of the ground wire when it is energized, and there is no prompt when the ground wire is energized. Summary of the invention

[0005] In order to solve the above problems in the prior art, that is, to solve the problem that the prior art can only protect the safety of the neutral and live wires when there is leakage, but cannot protect the safety of the ground wire when it is energized, and there is no prompt when the ground wire is energized, the present invention provides a water heater protection circuit and a protection method.

[0006] In a first aspect, the present invention provides a water heater protection circuit, characterized in that it comprises: a ground detection circuit;

[0007] The grounding detection circuit comprises: a ground detection circuit, an optocoupler control circuit, a main control MCU and a grounding indicator light;

[0008] The ground wire detection circuit is connected to the live wire and the ground wire respectively, the optocoupler control circuit is connected to the ground wire detection circuit and the main control MCU respectively, and the main control MCU is also connected to the ground indicator light;

[0009] The ground wire detection circuit is used to generate current in the positive cycle of the alternating current when the live wire and the ground wire of the alternating current are well connected;

[0010] The optical coupling control circuit is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU;

[0011] The main control MCU is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light to indicate normal.

[0012] Optionally, the ground line detection circuit includes a first resistor and a first diode, wherein:

[0013] The anode of the first diode is connected to the live wire, and the cathode of the first diode is connected to the optocoupler control circuit and the ground wire respectively through the first resistor.

[0014] Optionally, the ground line detection circuit further includes a second resistor and a second diode, wherein:

[0015] The second resistor is arranged on the ground line, the anode of the second diode is connected to the second resistor, and the cathode of the second resistor is connected to the first resistor.

[0016] Optionally, the optical coupling control circuit includes an optical coupling module and a capacitor; wherein the optical coupling module includes a light emitting diode and a phototransistor;

[0017] The positive electrode of the light emitting diode is connected to the negative electrode of the first diode, the negative electrode of the light emitting diode is connected to the ground wire, and the phototransistor is connected to the capacitor;

[0018] The capacitor is connected to the main control MCU;

[0019] Wherein, the optical coupling module is used to output a level square wave signal when the first diode is turned on.

[0020] Optionally, the water heater protection circuit also includes a grounding charged detection circuit; wherein

[0021] The grounding charged detection circuit includes a water heater housing and a grounding charged indicator light;

[0022] The water heater shell is connected to the live wire, the neutral wire and the ground wire respectively;

[0023] The grounded power indicator light is respectively connected to the water heater housing and a wall for fixing the water heater;

[0024] Among them, when the water heater leaks electricity, the water heater is short-circuited. If the ground wire is charged, the ground wire, the water heater shell, the grounded charged indicator light and the wall form a loop, and the grounded charged indicator light indicates an abnormality.

[0025] Optionally, the grounding charged detection circuit further includes: a leakage protection circuit, the leakage protection circuit includes: a leakage electromagnetic ring, a protection switch and the main control MCU;

[0026] The live wire and the neutral wire are wound around the leakage electromagnetic ring, the protection switch is respectively connected to the live wire, the main control MCU and the heating body of the heater, the main control MCU is also connected to the leakage electromagnetic ring and the protection switch, and the protection switch is also connected to the heating body of the water heater;

[0027] When leakage is triggered, the main control MCU detects the induced potential on the leakage electromagnetic ring and controls the protection switch to be disconnected.

[0028] Optionally, the leakage protection circuit further includes a thermostat, wherein the thermostat is connected to the live wire and the thyristor respectively;

[0029] The thermostat is used to detect the temperature of the heating body of the heater and is disconnected when the temperature is higher than a preset temperature.

[0030] Optionally, the protection switch is a thyristor, which is arranged on the live wire and is respectively connected to the thermostat, the main control MCU and the heating body.

[0031] Optionally, the protection switch includes a first electromagnetic relay and a second electromagnetic relay, the first electromagnetic relay is arranged on the live line and located upstream of the thermostat, and the second electromagnetic relay is located on the neutral line.

[0032] In a second aspect, the present invention further provides a water heater protection method, the method comprising:

[0033] The main control MCU determines whether the optical coupling control circuit outputs a square wave signal;

[0034] If a square wave signal is output, it is determined that the water heater is grounded normally, and the grounding indicator light is controlled to indicate normal;

[0035] If the square wave signal is not output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and the grounding indicator light is controlled to indicate an abnormality.

[0036] The present invention belongs to the field of smart home appliances, and specifically relates to a water heater protection circuit and a protection method. The water heater protection circuit includes: a grounding detection circuit; the grounding detection circuit includes: a ground wire detection circuit, an optocoupler control circuit, a main control MCU and a grounding indicator light; the ground wire detection circuit is connected to the live wire and the ground wire respectively, the optocoupler control circuit is connected to the ground wire detection circuit and the main control MCU respectively, and the main control MCU is also connected to the grounding indicator light; the ground wire detection circuit is used to generate current in the positive cycle of the alternating current when the live wire and the ground wire of the alternating current are well connected; the optocoupler control circuit is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU; the main control MCU is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light to indicate normal. The water heater protection method includes: the main control MCU determines whether the optical coupling control circuit outputs a square wave signal; if the square wave signal is output, it is determined that the water heater is grounded normally, and the grounding indicator light is controlled to indicate normal; if the square wave signal is not output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected reversely, and the grounding indicator light is controlled to indicate abnormality. Problem Solving The existing technology can only protect the safety of the neutral and live wires in the case of leakage, but cannot protect the safety of the ground wire being energized, and there is no prompt when the ground wire is energized. The safety risks of water heaters should be prevented and eliminated to avoid personal and property losses caused by safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 1 The water heater protection circuit provided by the present invention Figure 1 ;

[0039] Figure 2 The water heater protection circuit provided by the present invention Figure 2 ;

[0040] Figure 3 The water heater protection circuit provided by the present invention Figure 3 ;

[0041] Figure 4 The water heater protection circuit provided by the present invention Figure 4 ;

[0042] Figure 5 It is a schematic flow chart of the water heater protection method provided by the present invention. DETAILED DESCRIPTION

[0043] First, those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0044] Secondly, it should be noted that in the description of the embodiments of the present invention, the terms "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0045] In addition, it should be noted that in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Electric water heaters use heating wires to convert electrical energy into thermal energy, and then heat cold water into hot water through heat conduction. Because electric water heaters can heat hot water instantly, their power is generally high. Once an electric water heater leaks electricity, it poses a major safety hazard and threatens the user's personal safety.

[0048] In the prior art, the safety of water heaters is ensured mainly by means of safety grounding to protect against leakage, installing relays to ensure safe power off, and setting over-temperature protection to prevent water heaters from drying out. However, the prior art can only protect the safety of neutral and live wires when there is leakage, but cannot protect the safety of the ground wire when it is energized, and there is no warning when the ground wire is energized.

[0049] The present invention provides a water heater protection circuit and a protection method. The water heater protection circuit comprises: a grounding detection circuit; the grounding detection circuit comprises: a ground wire detection circuit, an optocoupler control circuit, a main control MCU and a grounding indicator light; the ground wire detection circuit is connected to the live wire and the ground wire respectively, the optocoupler control circuit is connected to the ground wire detection circuit and the main control MCU respectively, and the main control MCU is also connected to the grounding indicator light; the ground wire detection circuit is used to generate current in the positive cycle of the alternating current when the live wire and the ground wire of the alternating current are well connected; the optocoupler control circuit is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU; the main control MCU is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light to indicate normal. The water heater protection method includes: the main control MCU determines whether the optical coupling control circuit outputs a square wave signal; if the square wave signal is output, it is determined that the water heater is grounded normally, and the grounding indicator light is controlled to indicate normal; if the square wave signal is not output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and the grounding indicator light is controlled to indicate abnormality. The existing technology can only protect the safety of the neutral and live wires in the case of leakage, but cannot protect the safety of the ground wire when it is energized, and there is no prompt when the ground wire is energized, and the safety risks of the water heater are prevented and eliminated to avoid personal and property losses caused by safety hazards.

[0050] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the embodiments of the present invention and are not used to limit the scope of the embodiments of the present invention.

[0051] Figure 1 Water heater protection circuit provided by the present invention Figure 1 The water heater protection circuit includes a grounding detection circuit, which includes: a ground wire detection circuit 10, an optocoupler control circuit 11, a main control MCU 12 and a grounding indicator light 13; the grounding detection circuit is used to detect whether the live wire and the ground wire of the AC power are well connected and whether the live wire and the neutral wire of the AC power are connected reversely.

[0052] Among them, the ground wire detection circuit 10 is connected to the live wire and the ground wire respectively, the optical coupling control circuit 11 is connected to the ground wire detection circuit 10 and the main control MCU 12 respectively, and the main control MCU 12 is also connected to the ground indicator light 13. The ground wire detection circuit 10 is used to generate current when the live wire and the ground wire of the alternating current are well connected. Specifically, the ground wire detection circuit 10 is mainly composed of a 400K resistor and a diode. Through the 400K resistor and the diode, a small current Ia can be generated. This current Ia forms a square wave signal through the optical coupling control circuit 11 and is output to the main control MCU 12, thereby realizing the detection of whether the live wire and the ground wire of the alternating current are well connected and whether the live wire and the neutral wire of the alternating current are connected in reverse.

[0053] The optical coupler control circuit 11 is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU12. Specifically, the optical coupler control circuit 11 is mainly composed of an optical coupler, which is an optoelectronic device used to connect a transmission medium and a light source. The semiconductor photosensitive device can be a photodiode, a phototransistor, a Darlington transistor, a thyristor optical coupler, etc., and the present application does not limit this. The optical coupler is mainly composed of two mutually insulated metal electrodes (called emitters) and a receiving electrode connected to a ground electrode through an insulating layer. The way to generate the square wave signal by the optical coupler control circuit can be, for example: the input end of the optical coupler (generally a light-emitting diode) is connected to the output end of the signal generator, the output end of the optical coupler (generally a photosensitive transistor) is connected to the collector and emitter of the transistor, the base of the transistor is connected to the control end of the signal generator, and the resistor and capacitor are connected between the optical coupler and the transistor to form a stable square wave signal, and the present application does not limit this.

[0054] The main control MCU12 is also called a single-chip microcomputer chip. It is an integrated circuit that integrates a central processing unit (CPU), a memory (ROM, RAM) and various peripheral interfaces (such as input and output pins, timers, serial ports, etc.). In layman's terms, an MCU chip is like a small computer that integrates a processor, a memory and various functional modules. It is a chip specially designed to control and perform specific tasks, and is commonly used in various electronic devices and embedded systems. The main control MCU is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light to indicate normal. Specifically, the main control MCU12 receives the square wave signal generated by the optocoupler control circuit 11. If a square wave signal is output, it is determined that the water heater is grounded normally, and the main control MCU12 controls the grounding indicator light 13 to indicate normal; if no square wave signal is output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and the main control MCU12 controls the grounding indicator light 13 to indicate abnormality.

[0055] In this embodiment, the water heater protection circuit includes: a grounding detection circuit; wherein the grounding detection circuit includes: a ground detection circuit 10, an optocoupler control circuit 11, a main control MCU 12 and a grounding indicator light 13. The ground detection circuit 10 is connected to the live wire and the ground wire respectively, the optocoupler control circuit 11 is connected to the ground detection circuit 10 and the main control MCU 12 respectively, and the main control MCU 12 is also connected to the grounding indicator light 13. The ground detection circuit 10 is used to generate current when the live wire and the ground wire of the alternating current are well connected; the optocoupler control circuit 11 is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU 12; the main control MCU 12 is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light 13 to indicate normal. The problem that the existing technology can only protect the safety of the zero live wire leakage and cannot protect the safety of the ground wire with electricity is solved, and the safety risks of the water heater are prevented and eliminated to avoid personal and property losses caused by safety hazards.

[0056] Figure 2 Water heater protection circuit provided by the present invention Figure 2 In the above Figure 1 Based on the embodiments, this embodiment describes in detail the structure of the water heater protection circuit.

[0057] like Figure 2 As shown: the ground wire detection circuit 10 includes a first resistor 102 and a first diode 101, wherein the positive electrode of the first diode 101 is connected to the live wire, and the negative electrode of the first diode 101 is respectively connected to the optocoupler control circuit 11 and the ground wire through the first resistor 102. Further, the ground wire detection circuit 10 also includes a second resistor 104 and a second diode 103, wherein the second resistor 104 is arranged on the ground wire, the positive electrode of the second diode 103 is connected to the second resistor 104, and the negative electrode of the second resistor 104 is connected to the first resistor 102. Through the ground wire detection circuit 10, a small current Ia can be generated, and this current Ia forms a square wave signal through the optocoupler control circuit 11 and is output to the main control MCU 12, thereby realizing the detection of whether the live wire and the ground wire of the alternating current are well connected and whether the live wire and the neutral wire of the alternating current are reversely connected.

[0058] Further, the optocoupler control circuit 11 includes an optocoupler module 111 and a capacitor 112; wherein the optocoupler module 111 includes a light emitting diode and a phototransistor; the positive electrode of the light emitting diode is connected to the negative electrode of the first diode, the negative electrode of the light emitting diode is connected to the ground wire, and the phototransistor is connected to the capacitor; the capacitor 112 is connected to the main control MCU 12; wherein the optocoupler module 111 is used to output a level square wave signal when the first diode 101 is turned on. The optocoupler control circuit 11 can generate a square wave signal under the action of the current and send the square wave signal to the main control MCU 12. Specifically, in the positive half cycle of the alternating current, a small current Ia can be generated through the ground wire detection circuit 10, and this current Ia makes the optocoupler module 111 turn on in the positive half cycle of the alternating current; in the negative half cycle of the alternating current, the optocoupler module 111 is turned on and off, and finally generates the level square wave signal. Furthermore, since the optocoupler module 111 is an electronic device for isolating and transmitting signals, the signal is transmitted between the primary and secondary sides of the optocoupler through a photoelectric conversion device, but it may be affected by interference and noise during the transmission process, especially high-frequency noise. Through the capacitor 112, a low-pass filter can be formed to filter out high-frequency noise and improve the transmission quality and stability of the signal.

[0059] In this embodiment, the positive electrode of the first diode 101 is connected to the live wire, and the negative electrode of the first diode 101 is connected to the optocoupler control circuit 11 and the ground wire respectively through the first resistor 102. The second resistor 104 is arranged on the ground wire, the positive electrode of the second diode 103 is connected to the second resistor 104, and the negative electrode of the second resistor 104 is connected to the first resistor 102. The optocoupler control circuit 11 includes an optocoupler module 111 and a capacitor 112; wherein, the optocoupler module 111 includes a light-emitting diode and a phototransistor; the positive electrode of the light-emitting diode is connected to the negative electrode of the first diode, the negative electrode of the light-emitting diode is connected to the ground wire, and the phototransistor is connected to the capacitor; the capacitor 112 is connected to the main control MCU 12; the optocoupler module 111 is used to output a level square wave signal. The problem that the prior art can only protect the safety of the zero-live wire leakage and cannot protect the safety of the ground wire with electricity is solved, and the safety risks of the water heater are prevented and eliminated to avoid personal and property losses caused by safety hazards.

[0060] Figure 3 Water heater protection circuit provided by the present invention Figure 3 This embodiment describes in detail the structure of the water heater protection circuit.

[0061] like Figure 3As shown, the water heater protection circuit also includes a grounding charged detection circuit. Specifically, the grounding charged detection circuit is used to detect the situation where the ground wire is charged. When the water heater ground wire is charged, the water heater may have leakage, and the water heater shell is charged at this time.

[0062] When a user uses a water heater, if the shell of the water heater is charged, the user standing barefoot in the water may easily cause electric shock to the user. In addition, if the shell of the water heater is charged and there is water inside the water heater when the user uses the water heater, it may easily cause a short circuit inside the water heater, thereby causing a fire. Therefore, the present application designs the grounding charge detection circuit to detect the situation where the ground wire is charged.

[0063] Specifically, the grounding charged detection circuit includes a water heater shell 31 and a grounding charged indicator light 32; the water heater shell 31 is respectively connected to the live wire, the neutral wire and the ground wire; the grounding charged indicator light 32 is respectively connected to the water heater shell 31 and a wall 33 for fixing the water heater; wherein, when the water heater leaks electricity, the water heater is short-circuited, and if the ground wire is charged, the ground wire, the water heater shell 31, the grounding charged indicator light 32 and the wall 33 form a loop, and the grounding charged indicator light 32 indicates an abnormality.

[0064] Figure 4 Water heater protection circuit provided by the present invention Figure 4 In this embodiment Figure 3 On this basis, the method of protecting the ground wire of the water heater from being energized is explained in detail.

[0065] like Figure 4 As shown, the water heater protection circuit also includes a leakage protection circuit, which includes: a leakage electromagnetic ring 41, a protection switch 42 and the main control MCU43; wherein the live wire and the neutral wire are wound around the leakage electromagnetic ring 41, the protection switch 42 is respectively connected to the live wire, the main control MCU43 and the heater body 44, the main control MCU43 is also connected to the leakage electromagnetic ring 41 and the protection switch 42, and the protection switch 42 is also connected to the heater body 44 of the water heater; when leakage is triggered, the main control MCU43 detects the induced potential on the leakage electromagnetic ring 41 and controls the protection switch 42 to be disconnected.

[0066] Specifically, when the water heater is working normally, the current on the live wire and the neutral wire is equal. When the water heater has leakage, there is a deviation in the current on the live wire and the neutral wire. When the current difference exceeds 15mA, an induced electromotive force is generated in the leakage electromagnetic ring 41. In this circuit, the main control MCU43 can be, for example, a computer board, and the protection switch 42 can be, for example, a thyristor. The thyristor is arranged on the live wire and is connected to the thermostat 41, the main control MCU43 and the heating body 44 respectively. The thyristor is a semiconductor component that can work under high voltage and high current, and has the characteristics of high withstand voltage, fast response, no contact, small size, long life, no spark, no noise, etc. In the instant electric water heater, the thyristor plays the role of a solid-state relay, and the on-off state is adjusted by applying a signal to the thyristor, thereby realizing the start and stop of the heater. Compared with the traditional mechanical relay, it has greatly improved in performance and efficiency. Due to the use of advanced semiconductor technology, the conversion speed and response time can be improved while ensuring safety and stability. In addition, it also has the advantages of lower noise and longer life during use. In the present application, the computer board generates an induced electromotive force in the leakage electromagnetic ring and controls the thyristor to stop working, thereby stopping the internal heating tube in the water heater, and then stopping the water heater after leakage occurs, thereby protecting the life safety of the user.

[0067] In addition, the protection switch 42 can also be composed of a first electromagnetic relay and a second electromagnetic relay, wherein the first electromagnetic relay is arranged on the live wire and located upstream of the thermostat, and the second electromagnetic relay is located on the neutral wire. A relay is an electrical control device, which is an electrical appliance that causes a predetermined step change in the controlled quantity in the electrical output circuit when the change in the input quantity reaches the specified requirements. It has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop), and is usually used in automated control circuits. In fact, it is an "automatic switch" that uses a small current to control the operation of a large current, so it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit. In the present application, if the water heater has a leakage, the first electromagnetic relay and the second electromagnetic relay are disconnected on the live wire and the neutral wire, thereby stopping the water heater from working and protecting the life safety of the user.

[0068] The leakage protection circuit also includes a thermostat 45, wherein the thermostat 45 is connected to the live wire and the thyristor respectively; the thermostat 45 is used to detect the temperature of the heating body 44 of the heater, and is disconnected when the temperature is higher than the preset temperature. The thermostat 45 uses an advanced single-chip microcomputer as the control core and an imported high-performance temperature and humidity sensor device, which can simultaneously measure and control temperature and humidity signals and realize LCD digital display. The thermostat 45 can undergo physical deformation inside the switch according to the temperature change of the working environment, and the temperature controller issues a switch command, thereby controlling the operation of the device to achieve the ideal temperature.

[0069] In this embodiment, the water heater protection circuit also includes a grounding charged detection circuit; wherein the grounding charged detection circuit includes a water heater shell 31 and a grounding charged indicator light 32; the water heater shell 31 is respectively connected to the live wire, the neutral wire and the ground wire; the grounding charged indicator light 32 is respectively connected to the water heater shell 31 and a wall 33 for fixing the water heater; when the water heater leaks electricity, the water heater is short-circuited, and if the ground wire is charged, the ground wire, the water heater shell 31, the grounding charged indicator light 32 and the wall 33 form a loop, and the grounding charged indicator light 32 indicates an abnormality. The water heater protection circuit also includes: a leakage protection circuit, which includes: a leakage electromagnetic ring 41, a protection switch 42 and the main control MCU43; the live wire and the neutral wire are wound on the leakage electromagnetic ring 41, and the protection switch 42 is respectively connected to the live wire, the main control MCU43 and the heater body 44, and the main control MCU4 is also connected to the leakage electromagnetic ring 41 and the protection switch 42, and the protection switch 42 is also connected to the heater body 44 of the water heater; when the leakage is triggered, the main control MCU43 detects the induced potential on the leakage electromagnetic ring and controls the protection switch 42 to disconnect. The problem that the existing technology can only protect the safety of the neutral and live wires in the case of leakage, but cannot protect the safety of the ground wire with electricity is solved, and the safety risks of the water heater are prevented and eliminated to avoid personal and property losses caused by safety hazards.

[0070] Figure 5 Flow chart of the washing and care equipment control method provided by the present invention. This embodiment describes in detail the detection of whether the live wire and the ground wire of the alternating current are properly connected and whether the live wire and the neutral wire of the alternating current are reversely connected.

[0071] S101: Determine whether the optocoupler control circuit outputs a square wave signal; if so, execute step S103, if not, execute step S102.

[0072] The optical coupler control circuit receives the tiny current Ia generated by the ground wire detection circuit. This current Ia turns on the optical coupler module in the positive half cycle of the alternating current. In the negative half cycle of the alternating current, the optical coupler module turns on and off, and finally generates the level square wave signal. Therefore, by judging whether the optical coupler circuit outputs a square wave signal, it can be concluded whether the live wire and the ground wire of the alternating current are well connected and whether the live wire and the neutral wire of the alternating current are connected in reverse.

[0073] S102: Determine that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and control the grounding indicator light to indicate an abnormality.

[0074] Wherein, if the optocoupler control circuit does not output a square wave signal, it is determined that the water heater has poor grounding and / or the live wire and the neutral wire are connected in reverse. Wherein, the reasons for the poor grounding of the water heater may be, for example: leakage of the heating tube, failure of the thermostat, damage to the heating tube, poor contact of the water inlet pipe, aging of the internal parts of the water heater, etc. When the water heater is poorly grounded, the leakage of the water heater will cause abnormal current path of the human body, posing a threat to personal safety, especially when touching the electric water heater. When the live wire and the neutral wire of the water heater are connected in reverse, although the water heater switch will trip when leakage occurs, the live wire of the power supply will not be disconnected, which will also cause damage to the equipment and life. If the optocoupler control circuit does not output a square wave signal, the grounding detection circuit does not generate the tiny current Ia, then it is determined that the water heater has poor grounding and / or the live wire and the neutral wire are connected in reverse, and the grounding indicator light is controlled to indicate an abnormality to notify the user of the water heater to stop using the water heater to ensure safety.

[0075] S103: Determine that the water heater is grounded normally, and control the grounding indicator light to indicate normal.

[0076] If the optical coupling control circuit outputs a square wave signal, it is determined that the water heater is grounded normally. There will be no equipment or human damage caused by poor grounding of the water heater or reverse connection of the live wire and the neutral wire of the water heater. The grounding indicator light is controlled to indicate normal.

[0077] In this embodiment, the main control MCU determines whether the optical coupling control circuit outputs a square wave signal; if a square wave signal is output, it is determined that the water heater is grounded normally, and the grounding indicator light is controlled to indicate normal; if no square wave signal is output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and the grounding indicator light is controlled to indicate abnormality. The problem that the prior art can only protect the safety of the neutral and live wires in the case of leakage, but cannot protect the safety of the ground wire with electricity, prevents and eliminates the safety risks of the water heater, and avoids personal and property losses caused by safety hazards.

[0078] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments, and the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A water heater protection circuit, characterized in that: include: Ground detection circuit; in The grounding detection circuit comprises: a ground detection circuit, an optocoupler control circuit, a main control MCU and a grounding indicator light; The ground wire detection circuit is connected to the live wire and the ground wire respectively, the optocoupler control circuit is connected to the ground wire detection circuit and the main control MCU respectively, and the main control MCU is also connected to the ground indicator light; The ground wire detection circuit is used to generate current when the live wire and the ground wire of the alternating current are well connected; The optical coupling control circuit is used to generate a square wave signal under the action of the current, and send the square wave signal to the main control MCU; The main control MCU is used to confirm that the live wire and the ground wire are well connected according to the square wave signal, and control the grounding indicator light to indicate normal.

2. The water heater protection circuit according to claim 1, characterized in that: The ground line detection circuit includes a first resistor and a first diode, wherein: The anode of the first diode is connected to the live wire, and the cathode of the first diode is connected to the optocoupler control circuit and the ground wire respectively through the first resistor.

3. The water heater protection circuit according to claim 2, characterized in that: The ground line detection circuit also includes a second resistor and a second diode, wherein: The second resistor is arranged on the ground line, the anode of the second diode is connected to the second resistor, and the cathode of the second resistor is connected to the first resistor.

4. The water heater protection circuit according to claim 3, characterized in that: The optical coupling control circuit includes an optical coupling module and a capacitor; wherein the optical coupling module includes a light emitting diode and a phototransistor; The positive electrode of the light emitting diode is connected to the negative electrode of the first diode, the negative electrode of the light emitting diode is connected to the ground wire, and the phototransistor is connected to the capacitor; The capacitor is connected to the main control MCU; Wherein, the optical coupling module is used to output a level square wave signal.

5. The water heater protection circuit according to any one of claims 1 to 4, characterized in that: Also includes a ground live detection circuit; wherein The grounding charged detection circuit includes a water heater housing and a grounding charged indicator light; The water heater shell is connected to the live wire, the neutral wire and the ground wire respectively; The grounded power indicator light is respectively connected to the water heater housing and a wall for fixing the water heater; Among them, when the water heater leaks electricity, the water heater is short-circuited. If the ground wire is charged, the ground wire, the water heater shell, the grounded charged indicator light and the wall form a loop, and the grounded charged indicator light indicates an abnormality.

6. The water heater protection circuit according to claim 1, characterized in that: Also includes: A leakage protection circuit, the leakage protection circuit comprising: a leakage electromagnetic ring, a protection switch and the main control MCU; in The live wire and the neutral wire are wound around the leakage electromagnetic ring, the protection switch is respectively connected to the live wire, the main control MCU and the heating body of the heater, the main control MCU is also connected to the leakage electromagnetic ring and the protection switch, and the protection switch is also connected to the heating body of the water heater; When leakage is triggered, the main control MCU detects the induced potential on the leakage electromagnetic ring and controls the protection switch to be disconnected.

7. The water heater protection circuit according to claim 6, characterized in that: The leakage protection circuit further includes a thermostat, wherein the thermostat is connected to the live wire and the thyristor respectively; The thermostat is used to detect the temperature of the heating body of the heater and is disconnected when the temperature is higher than a preset temperature.

8. The water heater protection circuit according to claim 7, characterized in that: The protection switch is a thyristor, which is arranged on the live wire and is respectively connected to the temperature controller, the main control MCU and the heating body.

9. The water heater protection circuit according to claim 7, characterized in that: The protection switch includes a first electromagnetic relay and a second electromagnetic relay. The first electromagnetic relay is arranged on the live line and located upstream of the thermostat. The second electromagnetic relay is located on the neutral line.

10. A water heater protection method, characterized in that: The method is applied to the circuit according to any one of claims 1 to 9, and the method comprises: The main control MCU determines whether the optical coupling control circuit outputs a square wave signal; If a square wave signal is output, it is determined that the water heater is grounded normally, and the grounding indicator light is controlled to indicate normal; If the square wave signal is not output, it is determined that the water heater is poorly grounded and / or the live wire and the neutral wire are connected in reverse, and the grounding indicator light is controlled to indicate an abnormality.

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