Surge protection circuit, control device, washing pump assembly and household appliance

Abstract

The utility model provides a surge protection circuit, a control device, a washing pump assembly and a household appliance. The surge protection circuit comprises a differential mode surge absorption circuit which comprises a thermistor connected with a live wire; the first piezoresistor is connected with the thermistor and the zero line; the common mode surge absorption circuit comprises a gas discharge tube; the second piezoresistor and the gas discharge tube are connected in series between the live wire and the ground wire; and the third piezoresistor and the gas discharge tube are connected in series between the zero line and the ground wire. Therefore, the differential-mode surge voltage between the live wire and the zero wire can be absorbed through the differential-mode surge absorption circuit, the circuit is protected from differential-mode interference, the common-mode surge voltage between the live wire and the ground wire and between the zero wire and the ground wire can be absorbed through the common-mode surge absorption circuit, the surge voltage can be inhibited in all directions, and the stability and the anti-interference capability of the circuit are improved.

Description

Technical Field

[0001] This utility model relates to the field of home appliance technology, specifically to a surge protection circuit, a control device, a washing pump assembly, and a home appliance. Background Technology

[0002] The washing pump assembly includes a motor and a heating element. The heating element is controlled by AC high voltage, and its metal casing may become electrified during operation. If the internal insulation of the heating element is damaged, there is a risk of leakage. Therefore, in addition to the neutral and live control wires, the metal casing of the heating element also needs a separate grounding wire to allow for backflow in case of leakage, preventing electric shock.

[0003] However, due to limitations in the heating element manufacturing process, its insulation withstand voltage is restricted. When the heating element is subjected to EMC surge testing or encounters severe lightning weather, the surge voltage is often too high, causing the insulation layer of the heating element to break down and thus damaging the heating element, which reduces the circuit stability and anti-interference capability. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0005] Therefore, the first aspect of this utility model is to provide a surge protection circuit.

[0006] The second aspect of this utility model is to provide a control device.

[0007] The third aspect of this invention is to provide a washing pump assembly.

[0008] The fourth aspect of this utility model is to provide a household appliance.

[0009] In view of the above, according to the first aspect of the present invention, a surge protection circuit is proposed, comprising: a differential mode surge absorption circuit, comprising: a thermistor connected to the live wire; a first varistor connected to the thermistor and the neutral wire; a common mode surge absorption circuit, comprising: a gas discharge tube; a second varistor connected in series with the gas discharge tube between the live wire and the ground wire; and a third varistor connected in series with the gas discharge tube between the neutral wire and the ground wire.

[0010] Specifically, the surge protection circuit provided by this utility model includes a differential-mode surge absorption circuit and a common-mode surge absorption circuit.

[0011] The differential-mode surge absorption circuit includes a thermistor and a first varistor.

[0012] The first end of the thermistor is connected to the live wire, the first end of the first varistor is connected to the second end of the thermistor, and the second end of the first varistor is connected to the neutral wire.

[0013] Furthermore, the common-mode surge absorption circuit includes a gas discharge tube, a second varistor, and a third varistor.

[0014] The second varistor is connected in series with the gas discharge tube between the live wire and the ground wire; the third varistor is connected in series with the gas discharge tube between the neutral wire and the ground wire.

[0015] In this way, when the circuit is working, the differential-mode surge voltage between the live wire and the neutral wire can be absorbed by the differential-mode surge absorption circuit to protect the circuit from differential-mode interference, and the common-mode surge voltage between the live wire and the ground wire, and between the neutral wire and the ground wire can be absorbed by the common-mode surge absorption circuit, thus achieving all-round suppression of surge voltage and improving circuit stability and anti-interference capability.

[0016] In some technical solutions, optionally, the first end of the gas discharge tube is connected to the ground wire; the first end of the second varistor is connected to the live wire, and the second end of the second varistor is connected to the second end of the gas discharge tube; the first end of the third varistor is connected to the neutral wire, and the second end of the third varistor is connected to the second end of the gas discharge tube.

[0017] In this technical solution, the first end of the gas discharge tube is connected to the ground wire, the first end of the second varistor is connected to the live wire, the second end of the second varistor is connected to the second end of the gas discharge tube, the first end of the third varistor is connected to the neutral wire, and the second end of the third varistor is connected to both the second end of the gas discharge tube and the second end of the second varistor. In this way, by limiting the voltage peak through the second and third varistors, and then dissipating energy through internal discharge in the gas discharge tube, common-mode surge voltage suppression is achieved, improving circuit stability and anti-interference capability.

[0018] In some technical solutions, optionally, the first end of the gas discharge tube is connected to the live wire and the neutral wire respectively; the first end of the second varistor is connected to the ground wire, and the second end of the second varistor is connected to the second end of the gas discharge tube; the first end of the third varistor is connected to the ground wire, and the second end of the third varistor is connected to the second end of the gas discharge tube.

[0019] In this technical solution, the first end of the gas discharge tube is connected to the live wire and the neutral wire, respectively. The first ends of the second and third varistors are both connected to the ground wire, and the second ends of the second and third varistors are both connected to the second end of the gas discharge tube. This achieves another effective common-mode surge protection topology, which can guide the surge current to the ground wire when a surge voltage occurs, thus protecting the circuit.

[0020] In some technical solutions, the surge protection circuit may optionally include: a first capacitor connected in parallel with a first varistor; a common-mode inductor connected in parallel with the first capacitor; a second capacitor connected with the common-mode inductor and connected between the live wire and the ground wire; and a third capacitor connected with the common-mode inductor and connected between the neutral wire and the ground wire; wherein the thermistor, the common-mode inductor, the second varistor, and the gas discharge tube constitute the first common-mode surge absorption circuit; and the thermistor, the common-mode inductor, the third varistor, and the gas discharge tube constitute the second common-mode surge absorption circuit.

[0021] In this technical solution, the surge protection circuit also includes a first capacitor, a common-mode inductor, a second capacitor, and a third capacitor.

[0022] The first capacitor is connected in parallel with the first varistor, the common-mode inductor is connected in parallel with the first capacitor, the second capacitor is connected with the common-mode inductor and is connected between the live wire and the ground wire, and the third capacitor is connected with the common-mode inductor and is connected between the neutral wire and the ground wire.

[0023] Furthermore, the thermistor, common-mode inductor, second varistor, and gas discharge tube constitute the first common-mode surge absorption circuit. This circuit suppresses the common-mode surge (L-PE) between the live wire L and the ground wire PE. The common-mode surge (L-PE) originates from the live wire L, passes through the thermistor to the common-mode inductor, and then returns to the ground wire PE via the second varistor and the gas discharge tube. In this circuit, the second varistor limits the voltage peak, the gas discharge tube dissipates the energy, and the remaining lower voltage is then supplied to the downstream circuit.

[0024] Furthermore, the thermistor, common-mode inductor, third varistor, and gas discharge tube form the second common-mode surge absorption circuit. This second common-mode surge absorption circuit suppresses the common-mode surge (N-PE) between the neutral line N and the ground line PE. The common-mode surge (N-PE) originates from the neutral line N, passes through the thermistor to the common-mode inductor, and then returns to the ground line PE via the third varistor and the gas discharge tube. In the second common-mode surge absorption circuit, the third varistor limits the voltage peak value, and the energy is dissipated through internal discharge in the gas discharge tube. The remaining lower voltage is then supplied to the downstream circuit.

[0025] By adding the first capacitor, common-mode inductor, second capacitor, and third capacitor, the filtering function can be further improved. Together with the original surge absorption elements, they form a more complex surge absorption circuit, which can filter out interference signals of different frequencies, improve the circuit's adaptability to complex electromagnetic environments, and enhance surge protection and electromagnetic compatibility performance.

[0026] According to a second aspect of the present invention, a control device is provided, comprising: a surge protection circuit as described in any of the technical solutions of the first aspect, connected to the power grid, the surge protection circuit being used to suppress surge voltage between power grid conductors; and a switching power supply, connected to the surge protection circuit and the load, the switching power supply being used to convert AC power input from the power grid into DC power for use by the load.

[0027] Specifically, the control device provided by this utility model includes the surge protection circuit in any of the technical solutions of the first aspect described above. Therefore, the control device proposed in the second aspect of this utility model possesses all the beneficial effects of the surge protection circuit in the technical solution of the first aspect described above, and will not be repeated here.

[0028] The surge protection circuit is connected to the power grid and is used to suppress surge voltage between power grid conductors.

[0029] Furthermore, the control device also includes a switching power supply, which is connected to the surge protection circuit and the load. The switching power supply is used to convert the AC power input from the power grid into DC power for the load to use.

[0030] In some technical solutions, the control device may optionally include: an intelligent power module connected to the switching power supply and the load, the intelligent power module being used to control the power of the load; and a relay connected to the switching power supply and the load, the relay being used to control the on / off state of the load path.

[0031] In this technical solution, the control device also includes an intelligent power module and a relay.

[0032] The intelligent power module is connected to the switching power supply and the load, and is used to control the power of the load.

[0033] Furthermore, the relay is connected to the switching power supply and the load, and is used to control the on / off state of the load path.

[0034] In some technical solutions, the switching power supply may optionally include: a rectifier and filter circuit connected to a surge protection circuit, wherein the rectifier and filter circuit is used to rectify and filter the AC power input from the power grid.

[0035] In this technical solution, the aforementioned switching power supply may specifically include a rectifier and filter circuit.

[0036] The rectifier and filter circuit is connected to the surge protection circuit. The rectifier and filter circuit is used to rectify and filter the AC power input from the power grid to convert the AC power input from the power grid into DC power for the load. At the same time, it reduces the ripple component in the output DC voltage, improves the purity of the output voltage, makes the output DC voltage more stable, and reduces voltage fluctuations.

[0037] In some technical solutions, optionally, the rectifier filter circuit includes: a first diode connected between the live wire and the ground terminal of the switching power supply; a second diode connected between the live wire and the universal bus; a third diode connected between the neutral wire and the universal bus; a fourth diode connected between the neutral wire and the ground terminal of the switching power supply; a fourth capacitor connected between the universal bus and the ground terminal of the switching power supply; and an electrolytic capacitor connected in parallel with the fourth capacitor; wherein, the thermistor and the first varistor in the surge protection circuit form a first differential-mode surge absorption circuit; and the thermistor, the common-mode inductor, and the electrolytic capacitor in the surge protection circuit form a second differential-mode surge absorption circuit.

[0038] In this technical solution, the aforementioned rectifier and filter circuit may specifically include a first diode, a second diode, a third diode, a fourth diode, a fourth capacitor, and an electrolytic capacitor.

[0039] The first diode is connected between the live wire and the ground terminal of the switching power supply.

[0040] Furthermore, a second diode is connected between the fire wire and the general bus.

[0041] Furthermore, a third diode is connected between the neutral wire and the universal bus.

[0042] Furthermore, the fourth diode is connected between the neutral wire and the ground terminal of the switching power supply.

[0043] Furthermore, both the fourth capacitor and the electrolytic capacitor are connected between the general-purpose bus and the ground terminal of the switching power supply.

[0044] In the surge protection circuit, the thermistor and the first varistor form the first differential-mode surge absorption circuit. For differential-mode surges (LN) between the live wire and the neutral wire, the surge voltage is clamped through the thermistor and the first varistor, which can effectively reduce the bus voltage of the downstream switching power supply.

[0045] Furthermore, the thermistor, common-mode inductor, and electrolytic capacitor in the surge protection circuit form the second differential-mode surge absorption circuit. After the differential-mode surge (LN) between the live wire and the neutral wire is absorbed by the first differential-mode surge absorption circuit, it can then pass through the common-mode inductor and the bus electrolytic capacitor to form an LC filter, thereby suppressing the bus voltage even further.

[0046] In this way, the differential mode surge (LN) between the live wire and the neutral wire can be clamped at its maximum value by the thermistor, the first varistor, the common mode inductor and the electrolytic capacitor, limiting the peak pulse voltage and thus effectively reducing the bus voltage of the downstream switching power supply.

[0047] According to a third aspect of this utility model, a washing pump assembly is provided, comprising: a control device as described in any of the technical solutions of the second aspect above, connected to the power grid; a pump body; a motor, connected to the control device and the pump body; and a heating element, connected to the control device; wherein the control device is used to control the operation of the motor and the heating element, so that the motor drives the pump body to draw in or output washing liquid, and the heating element heats the washing liquid.

[0048] The washing pump assembly provided by this utility model includes the control device in any of the technical solutions of the second aspect described above. Therefore, the washing pump assembly proposed in the third aspect of this utility model possesses all the beneficial effects of the control device in the technical solution of the second aspect described above, which will not be repeated here.

[0049] Furthermore, the washing pump assembly also includes a pump body, a motor, and a heating element.

[0050] The motor is connected to the control device and the pump body, the heating element is connected to the control device, and the control device is connected to the power grid.

[0051] Furthermore, the control device is used to control the operation of the motor and the heating element, so that the motor drives the pump to draw in or output washing liquid, and the heating element heats the washing liquid.

[0052] According to a fourth aspect of the present invention, a household appliance is provided, comprising: the washing pump assembly described in the third aspect above.

[0053] The household appliance proposed in the fourth aspect of this utility model includes the washing pump assembly in the third aspect of the above-mentioned technical solution. Therefore, the household appliance proposed in the fourth aspect of this utility model possesses all the beneficial effects of the washing pump assembly in the third aspect of the above-mentioned technical solution, which will not be repeated here.

[0054] In practical applications, the aforementioned home appliances include, but are not limited to, dishwashers, washing machines, electric water heaters, fully automatic coffee machines, and steam garment steamers, etc., without specific restrictions.

[0055] Additional aspects and advantages of this invention will become apparent in the description that follows, or may be learned by practice of this invention. Attached Figure Description

[0056] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0057] Figure 1 A circuit diagram of a surge protection circuit according to an embodiment of the present invention is shown;

[0058] Figure 2A schematic diagram of the structure of a washing pump assembly in the related art is shown;

[0059] Figure 3 A circuit diagram of a differential-mode surge suppression circuit in the related art is shown;

[0060] Figure 4 An equivalent circuit diagram of the surge protection circuit according to an embodiment of the present invention is shown;

[0061] Figure 5 A schematic diagram of lightning surge test results for differential mode surge suppression circuits in related technologies is shown.

[0062] Figure 6 A schematic diagram showing the lightning surge test results of the surge protection circuit according to an embodiment of the present invention is provided.

[0063] Figure 7 A structural block diagram of the control device according to an embodiment of the present invention is shown;

[0064] Figure 8 A structural block diagram of the washing pump assembly according to an embodiment of the present invention is shown;

[0065] Figure 9 A structural block diagram of a household appliance according to an embodiment of the present invention is shown.

[0066] Figure 1 The correspondence between the labels and the entity structures:

[0067] 100 Surge protection circuit, 102 Differential mode surge absorption circuit, 104 Thermistor, 106 First varistor, 108 Common mode surge absorption circuit, 110 Gas discharge tube, 112 Second varistor, 114 Third varistor, 116 First capacitor, 118 Common mode inductor, 120 Second capacitor, 122 Third capacitor, 208 Rectifier and filter circuit, 210 First diode, 212 Second diode, 214 Third diode, 216 Fourth diode, 218 Fourth capacitor, 220 Electrolytic capacitor. Detailed Implementation

[0068] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of this utility model and the features thereof can be combined with each other.

[0069] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0070] The following is combined Figures 1 to 9 The surge protection circuit, control device, washing pump assembly, and household appliances provided in this application will be described in detail through specific embodiments and application scenarios.

[0071] In one embodiment of this utility model, such as Figure 1 As shown, a surge protection circuit 100 is proposed.

[0072] The surge protection circuit 100 includes a differential mode surge absorption circuit 102 and a common mode surge absorption circuit 108.

[0073] The differential mode surge absorption circuit 102 includes a thermistor 104 and a first varistor 106.

[0074] The first end of the thermistor 104 is connected to the live wire L, the first end of the first varistor 106 is connected to the second end of the thermistor 104, and the second end of the first varistor 106 is connected to the neutral wire N.

[0075] Furthermore, the common-mode surge absorption circuit 108 includes a gas discharge tube 110, a second varistor 112, and a third varistor 114.

[0076] The second varistor 112 is connected in series with the gas discharge tube 110 between the live wire L and the ground wire PE; the third varistor 114 is connected in series with the gas discharge tube 110 between the neutral wire N and the ground wire PE.

[0077] In this way, when the circuit is working, the differential mode surge absorption circuit 102 can absorb the differential mode surge voltage between the live wire and the neutral wire, protecting the circuit from differential mode interference, and the common mode surge absorption circuit 108 can absorb the common mode surge voltage between the live wire and the ground wire, and between the neutral wire and the ground wire, thus achieving all-round suppression of surge voltage and improving circuit stability and anti-interference capability.

[0078] Among them, thermistor 104 is a negative temperature coefficient thermistor. When the home appliance is turned on, the resistance of thermistor 104 is relatively large due to the low temperature, which can limit the surge current and prevent excessive current from impacting the circuit when the appliance is turned on. As the current passes through, thermistor 104 heats up and the resistance decreases. When the home appliance is working normally, thermistor 104 has little impact on the circuit.

[0079] Furthermore, the first varistor 106, the second varistor 112, and the third varistor 114 are used for overvoltage protection. When a momentary high voltage occurs in the circuit, the resistance of the first varistor 106, the second varistor 112, and the third varistor 114 decreases rapidly, thereby dissipating the overvoltage energy and protecting the subsequent circuit components from being damaged by the excessive voltage.

[0080] Furthermore, the gas discharge tube 110 can quickly conduct during high-voltage surges, releasing overvoltage energy to the ground, thereby protecting the downstream circuitry.

[0081] Furthermore, varistors are voltage clamping devices with nanosecond-level response speeds, but their ability to continuously withstand energy is limited; discharge tubes are switching devices with microsecond-level response speeds, but their current carrying capacity is large, reaching tens of kiloamperes. When a varistor and a discharge tube are used in series, the varistor can quickly limit the voltage peak, and the discharge tube then conducts to discharge the main energy. If a discharge tube is used alone, because its response time is slower than that of the varistor, the varistor needs to quickly clamp the initial surge voltage spike. If a varistor is used alone, repeated surge impacts will cause its leakage current to increase until it fails. With a discharge tube in series, when the clamping voltage rises due to varistor aging, the discharge tube can conduct earlier to share the impact energy, extending the varistor's lifespan by 3 to 5 times. Moreover, when providing common-mode surge protection for the ground (PE), using only a varistor will cause the varistor to short-circuit and fail, resulting in leakage risk. Therefore, when providing common-mode surge protection for the ground (PE), a varistor and a discharge tube need to be used in series.

[0082] It is understandable that, such as Figure 2 As shown, for the washing pump assembly, during a lightning surge, as Figure 2 As shown by the dotted line, the common-mode surge (N-PE) between the neutral and ground wires originates from the neutral wire N, passes through the power line to the neutral wire N of the heating element inside the washing pump assembly, and then returns to the ground wire in the power grid through the insulation layer of the heating element, thus forming a high-voltage loop. If there is no protection along the common-mode surge path, the residual surge voltage may exceed the range specified in the heating element's datasheet, easily causing the insulation layer of the heating element to break down, leading to heating failures and other problems in the washing pump assembly.

[0083] Furthermore, in related technologies, such as Figure 3As shown, a differential-mode surge suppression circuit in a filter circuit is proposed. Based on this differential-mode surge suppression circuit, for the differential-mode surge (LN) between the live wire L and the neutral wire N, the surge voltage is clamped through the thermistor NTC1 and the varistor ZR1, which can effectively reduce the bus voltage of the downstream switching power supply and protect the power supply chip and AC control load. For example, if the surge test input voltage is 4kV, the voltage value between the live wire L and the neutral wire N can be clamped to 925V using a 14D561K varistor, thereby effectively protecting the downstream devices. Furthermore, based on the above differential-mode surge suppression circuit, after the differential-mode surge (LN) between the live wire and the neutral wire is absorbed through the above path, it can be further filtered by the common-mode inductor L1 and the bus electrolytic capacitor E1 to form an LC (inductor-capacitor) filter, so as to suppress the bus voltage even lower. With proper selection, it can be lower than 600V. For the washing pump assembly, the aforementioned differential mode surge suppression circuit can achieve differential mode surge protection by using thermistor NTC1, varistor ZR1, common mode inductor L1 and bus electrolytic capacitor E1. That is, it protects the voltage difference between the power grid and the live and neutral wires when a lightning surge occurs. However, it does not provide effective protection for common mode surges, such as common mode surges between the live wire L and the ground wire PE, and common mode surges between the neutral wire N and the ground wire PE. This can easily lead to the problem of insulation layer breakdown damage of the heating tube. For example, if the pulse common mode voltage generated by a natural lightning strike or a large capacitive load connected to the power grid is higher than the insulation withstand voltage of the heating tube itself, it will cause heating failure of the washing pump assembly.

[0084] Therefore, in the surge protection circuit 100 provided by this utility model, a common-mode surge absorption circuit 108 composed of a second varistor 112, a third varistor 114 and a gas discharge tube 110 is proposed to improve the practicality of the circuit and reduce the risk of leakage after the heating element is damaged and the insulation layer is destroyed in the household appliance.

[0085] Among them, the gas discharge tube 110 is a voltage-sensitive switch. When the gas discharge tube 110 is not triggered, the inert gas inside the sealed tube of the gas discharge tube 110 maintains high insulation, and the gas discharge tube 110 is equivalent to an open circuit. When the external voltage exceeds the DC breakdown threshold of the gas discharge tube 110, the inert gas molecules inside the sealed tube undergo collision ionization, thereby generating an avalanche effect, which can form plasma conduction within microseconds and realize the discharge of thousands of amperes of surge current.

[0086] Thus, a common-mode surge absorption circuit 108 is designed in home appliances. Utilizing the working principles of the second varistor 112, the third varistor 114, and the gas discharge tube 110, the second varistor 112 and the third varistor 114 are connected in series with the gas discharge tube 110. The second varistor 112 and the third varistor 114 can quickly limit voltage peaks, and the gas discharge tube 110 then conducts to discharge the main energy. Based on this, when a large surge pulse voltage occurs in the power grid, the second varistor 112 and the third varistor 114 limit the voltage peak, and the energy is consumed by internal discharge in the gas discharge tube 110. The remaining lower voltage is then supplied to the downstream components, such as the insulation layer of the heating element. This effectively suppresses the spike voltage from the power grid entering the internal electronic control devices of the home appliance, protecting components such as the heating element and enhancing product reliability and lifespan.

[0087] In some embodiments of this utility model, optionally, such as Figure 1 As shown, the second varistor 112 and the third varistor 114 are connected to the live wire and the neutral wire respectively, and then the second varistor 112 and the third varistor 114 connected in parallel are connected in series with the gas discharge tube 110.

[0088] Specifically, the first end of the gas discharge tube 110 is connected to the ground wire, the first end of the second varistor 112 is connected to the live wire, the second end of the second varistor 112 is connected to the second end of the gas discharge tube 110, the first end of the third varistor 114 is connected to the neutral wire, and the second end of the third varistor 114 is connected to both the second end of the gas discharge tube 110 and the second end of the second varistor 112. At this time, the equivalent circuit diagram of the surge protection circuit 100 can be as follows: Figure 4 As shown.

[0089] For differential-mode surges (LN) between the live and neutral wires, the differential-mode surge absorption circuit 102 suppresses them. For common-mode surges (L-PE) between the live and ground wires, the second varistor 112 limits the voltage peak, and the energy is then dissipated through internal discharge in the gas discharge tube 110, with the remaining lower voltage supplied to the downstream circuit. For common-mode surges (N-PE) between the neutral and ground wires, the third varistor 114 limits the voltage peak, and the energy is then dissipated through internal discharge in the gas discharge tube 110, with the remaining lower voltage supplied to the downstream circuit. This achieves comprehensive surge voltage suppression, improving circuit stability and anti-interference capabilities.

[0090] In some embodiments of this utility model, optionally, the position of the gas discharge tube 110 can be interchanged with the positions of the second varistor 112 and the third varistor 114. That is, after the second varistor 112 and the third varistor 114 are connected in parallel to the ground wire, the parallel-connected second varistor 112 and the third varistor 114 are then connected in series with the gas discharge tube 110.

[0091] Specifically, the first end of the gas discharge tube 110 is connected to the live wire and the neutral wire, respectively. The first ends of the second varistor 112 and the third varistor 114 are both connected to the ground wire, and the second ends of the second varistor 112 and the third varistor 114 are both connected to the second end of the gas discharge tube 110. This achieves another effective common-mode surge protection topology, which can guide the surge current to the ground wire when a surge voltage occurs, thus protecting the circuit.

[0092] In some embodiments of this utility model, optionally, such as Figure 1 As shown, the surge protection circuit 100 also includes a first capacitor 116, a common-mode inductor 118, a second capacitor 120, and a third capacitor 122.

[0093] In this configuration, the first capacitor 116 is connected in parallel with the first varistor 106, the common-mode inductor 118 is connected in parallel with the first capacitor 116, the second capacitor 120 is connected with the common-mode inductor 118 and is connected between the live wire and the ground wire, and the third capacitor 122 is connected with the common-mode inductor 118 and is connected between the neutral wire and the ground wire.

[0094] Furthermore, the first capacitor 116 is connected between the live wire and the neutral wire to filter out electromagnetic interference, i.e., differential mode interference, between the live wire and the neutral wire, thus ensuring the stability of the power input.

[0095] Furthermore, the second capacitor 120 and the third capacitor 122 are connected across the live wire and the ground wire, and the neutral wire and the ground wire, respectively, to filter out electromagnetic interference (i.e., common-mode interference) between the live wire and the ground wire, and the neutral wire and the ground wire, thereby improving the circuit's anti-interference capability.

[0096] Furthermore, the common-mode inductor 118 presents high impedance to common-mode interference, which can effectively suppress the passage of common-mode interference signals, while presenting low impedance to normal differential-mode current, which does not affect normal power supply.

[0097] Furthermore, the thermistor 104, common-mode inductor 118, second varistor 112, and gas discharge tube 110 form the first common-mode surge absorption circuit. This first common-mode surge absorption circuit suppresses the common-mode surge (L-PE) between the live wire L and the ground wire PE. The common-mode surge (L-PE) originates from the live wire L, passes through the thermistor 104 to the common-mode inductor 118, and then returns to the ground wire PE through the second varistor 112 and the gas discharge tube 110. In the first common-mode surge absorption circuit, the voltage peak is limited by the second varistor 112, and energy is dissipated through internal discharge in the gas discharge tube 110. The remaining lower voltage is then supplied to the downstream circuit.

[0098] Furthermore, the thermistor 104, common-mode inductor 118, third varistor 114, and gas discharge tube 110 form a second common-mode surge absorption circuit. This second common-mode surge absorption circuit suppresses the common-mode surge (N-PE) between the neutral line N and the ground line PE. The common-mode surge (N-PE) originates from the neutral line N, passes through the thermistor 104 to the common-mode inductor 118, and then returns to the ground line PE through the third varistor 114 and the gas discharge tube 110. In the second common-mode surge absorption circuit, the voltage peak is limited by the third varistor 114, and energy is dissipated through internal discharge in the gas discharge tube 110. The remaining lower voltage is then supplied to the downstream end.

[0099] By adding the first capacitor 116, the common-mode inductor 118, the second capacitor 120, and the third capacitor 122, the filtering function can be further improved. Together with the original surge absorption element, it forms a more complex surge absorption circuit, which can filter out interference signals of different frequencies, improve the circuit's adaptability to complex electromagnetic environments, and enhance surge protection and electromagnetic compatibility performance.

[0100] When the surge protection circuit 100 is applied in the washing pump assembly, under normal circumstances, the insulation resistance of the heating tube, i.e., the resistance between the live wire or neutral wire and the ground wire, is infinite. When a lightning surge occurs, if the surge voltage applied to the second varistor 112 and the third varistor 114 exceeds the operating voltage value of the common-mode surge absorption circuit 108, the current flowing through the second varistor 112 and the third varistor 114 surges. The second varistor 112 and the third varistor 114 are equivalent to resistors with infinite resistance. Therefore, the surge energy will be preferentially consumed through the first common-mode surge absorption circuit and the second common-mode surge absorption circuit. After the energy is reduced, the voltage transmitted to the two ends of the insulation layer of the heating tube at the rear end will be significantly reduced, which can effectively protect the heating tube.

[0101] For example, if the surge test voltage is 4kV and the downstream voltage requirement is lower than the insulation withstand voltage of the thick-film heating tube (1200V), a second varistor 112 and a third varistor 114 (470V) are selected and connected in series with a 2500V gas discharge tube 110. The accuracy of the second varistor 112, the third varistor 114, and the gas discharge tube 110 is 20%. Furthermore, considering that the second varistor 112 and the third varistor 114 operate at a lower accuracy limit of 376V, and the gas discharge tube 110 operates at a lower accuracy limit of 2000V, the lower limit of the operating voltage of the common-mode surge absorption circuit 108 is 376V + 2000V = 2376V > 1200V. Considering that the second varistor 112 and the third varistor 114 operate at an upper accuracy limit of 564V, and the gas discharge tube 110 operates at an upper accuracy limit of 3000V, the upper limit of the operating voltage of the common-mode surge absorption circuit 108 is 564V + 3000V = 3564V > 1200V.

[0102] Furthermore, to ensure that the common-mode surge absorption circuit 108 does not activate during the power-on moment and normal operation of the home appliance, and thus does not affect the service life of the second varistor 112, the third varistor 114, and the gas discharge tube 110, the common-mode surge absorption circuit 108 is limited to activating only when a lightning surge occurs. The operating voltage range of the common-mode surge absorption circuit 108 is limited to 2376V to 3564V. Based on this, using the above-mentioned surge protection circuit 100 can effectively reduce the voltage of the heating element insulation layer to below 1000V.

[0103] Specifically, before adding the second varistor 112, the third varistor 114, and the gas discharge tube 110 to the surge protection circuit 100, the measured residual surge voltage of the heating tube neutral line N to ground line PE during a 4kV lightning surge was as follows. Figure 5 As shown, when a lightning surge occurs, the voltage across the insulation layer of the heating tube is Vmax = 1.74kV, which is greater than the insulation withstand voltage of 1200V specified in the datasheet. Furthermore, multiple lightning surges will cause the insulation layer performance to deteriorate, and the insulation withstand voltage will decrease accordingly. After multiple surge tests, the heating tube will be damaged and malfunction.

[0104] Furthermore, after adding a second varistor 112, a third varistor 114, and a gas discharge tube 110 to the surge protection circuit 100, the residual surge voltage of the heating tube neutral line N to ground line PE was measured when a lightning surge of 4kV occurred. Figure 6 As shown, when a lightning surge occurs, the voltage peak is limited by the second varistor 112 and the third varistor 114, and the energy is consumed by the internal discharge of the gas discharge tube 110. The voltage Vmax across the insulation layer of the heating tube is 0.73kV, which is lower than the insulation withstand voltage of 1200V specified in the specification. Moreover, the heating tube works normally and is undamaged after multiple lightning surges.

[0105] In practical applications, the operating voltage parameters of the second varistor 112, the third varistor 114, and the gas discharge tube 110 can be adjusted according to the surge input voltage at the front end and the withstand voltage of the downstream devices. For example, a 470V second varistor 112, a 470V third varistor 114 + a 2500V gas discharge tube 110 can be replaced with a 680V second varistor 112, a 680V third varistor 114 + a 2000V gas discharge tube 110. No specific restrictions are imposed here.

[0106] In one embodiment of this utility model, such as Figure 7 As shown, a control device 200 is also proposed.

[0107] The control device 200 includes a surge protection circuit 100. Therefore, the control device 200 has all the beneficial effects of the surge protection circuit 100, which will not be described in detail here.

[0108] The surge protection circuit 100 is connected to the power grid and is used to suppress surge voltage between power grid conductors.

[0109] Furthermore, the control device 200 also includes a switching power supply 202, which is connected to the surge protection circuit 100 and the load. The switching power supply 202 is used to convert the AC power input from the power grid into DC power for the use of the load.

[0110] In some embodiments of this utility model, optionally, such as Figure 7 As shown, the control device 200 also includes an intelligent power module 204 and a relay 206.

[0111] The intelligent power module 204 is connected to the switching power supply 202 and the load, and is used to control the power of the load.

[0112] Furthermore, relay 206 is connected to switching power supply 202 and load, and relay 206 is used to control the on / off state of load path.

[0113] In practical applications, the aforementioned load can specifically be a motor and a heating element, and the aforementioned relay 206 can specifically be a heating element relay, used to control the heating element to turn on or off.

[0114] In some embodiments of this utility model, optionally, such as Figure 7 As shown, the aforementioned switching power supply 202 may specifically include a rectifier and filter circuit 208.

[0115] The rectifier and filter circuit 208 is connected to the surge protection circuit 100. The rectifier and filter circuit 208 is used to rectify and filter the AC power input from the power grid to convert the AC power input from the power grid into DC power for the load. At the same time, it reduces the ripple component in the output DC voltage, improves the purity of the output voltage, makes the output DC voltage more stable, and reduces voltage fluctuations.

[0116] In some embodiments of this utility model, optionally, such as Figure 1 As shown, the rectifier and filter circuit 208 may specifically include a first diode 210, a second diode 212, a third diode 214, a fourth diode 216, a fourth capacitor 218, and an electrolytic capacitor 220.

[0117] The first diode 210 is connected between the live wire and the ground terminal PGND (Power Ground) of the switching power supply 202. The anode of the first diode 210 is connected to the ground terminal of the switching power supply 202, and the cathode of the first diode 210 is connected to the live wire and the common mode inductor 118 in the surge protection circuit 100.

[0118] Furthermore, the second diode 212 is connected between the live wire and UBUS (Universal Bus). The anode of the second diode 212 is connected to the live wire, the common mode inductor 118 in the surge protection circuit 100, and the cathode of the first diode 210. The cathode of the second diode 212 is connected to the universal bus.

[0119] Furthermore, the third diode 214 is connected between the neutral line and the general bus. The anode of the third diode 214 is connected to the neutral line and the common mode inductor 118 in the surge protection circuit 100, and the cathode of the third diode 214 is connected to the general bus.

[0120] Furthermore, the fourth diode 216 is connected between the neutral line and the ground terminal of the switching power supply 202. The anode of the fourth diode 216 is connected to the ground terminal of the switching power supply 202, and the cathode of the fourth diode 216 is connected to the neutral line, the common mode inductor 118 in the surge protection circuit 100, and the anode of the third diode 214.

[0121] Furthermore, the fourth capacitor 218 and the electrolytic capacitor 220 are both connected between the general-purpose bus and the ground terminal of the switching power supply 202. The first terminal of the fourth capacitor 218 and the first terminal of the electrolytic capacitor 220 are both connected to the general-purpose bus, and the second terminal of the fourth capacitor 218 and the second terminal of the electrolytic capacitor 220 are both connected to the ground terminal of the switching power supply 202.

[0122] In this rectifier bridge, diodes 210, 212, 214, and 216 form a rectifier bridge that converts the input AC power into DC power. During the positive half-cycle of the AC voltage, diodes 210 and 214 conduct, while diodes 212 and 216 are cut off. During the negative half-cycle of the AC voltage, diodes 212 and 216 conduct, while diodes 210 and 214 conduct, thus achieving full-wave rectification.

[0123] Furthermore, the electrolytic capacitor 220 is used to smooth the pulsating DC voltage after rectification, store electrical energy, make the output DC voltage more stable, and reduce voltage fluctuations.

[0124] Furthermore, the fourth capacitor 218 is used for auxiliary filtering to further reduce the ripple component in the output DC voltage and improve the purity of the output voltage.

[0125] Furthermore, the thermistor 104 and the first varistor 106 in the surge protection circuit 100 form a first differential-mode surge absorption circuit. For differential-mode surges (LN) between the live wire and the neutral wire, the surge voltage is clamped through the thermistor 104 to the first varistor 106, which can effectively reduce the bus voltage of the downstream switching power supply 202.

[0126] Furthermore, the thermistor 104, the common-mode inductor 118 in the surge protection circuit 100, and the electrolytic capacitor 220 form the second differential-mode surge absorption circuit. After the differential-mode surge (LN) between the live wire and the neutral wire is absorbed by the first differential-mode surge absorption circuit, it can then pass through the common-mode inductor 118 and the bus electrolytic capacitor 220 to form an LC filter, thereby suppressing the bus voltage even lower.

[0127] In this way, the differential mode surge (LN) between the live wire and the neutral wire can be clamped at its maximum value by the thermistor 104, the first varistor 106, the common mode inductor 118 and the electrolytic capacitor 220, limiting the peak value of the pulse voltage, thereby effectively reducing the bus voltage of the downstream switching power supply 202.

[0128] In one embodiment of this utility model, such as Figure 8 As shown, a washing pump assembly 300 is also proposed.

[0129] The washing pump assembly 300 includes a control device 200. Therefore, the washing pump assembly 300 possesses all the beneficial effects of the control device 200, which will not be elaborated further here.

[0130] Furthermore, the washing pump assembly 300 also includes a pump body 302, a motor 304, and a heating element 306.

[0131] Among them, the motor 304 is connected to the control device 200 and the pump body 302, the heating tube 306 is connected to the control device 200, and the control device 200 is connected to the power grid.

[0132] Furthermore, the control device 200 is used to control the operation of the motor 304 and the heating tube 306, so that the motor 304 drives the pump body 302 to draw in or output washing liquid, and the heating tube 306 heats the washing liquid.

[0133] In practical applications, heating tube 306 includes, but is not limited to, PTC (Positive Temperature Coefficient) heating tubes, quartz tubes, thick-film instantaneous heating tubes, etc., without specific restrictions.

[0134] Among them, the insulation withstand voltage of PTC heating tube is 1800V, that of quartz tube is 1500V, and that of thick film instantaneous heating tube is 1200V.

[0135] In one embodiment of this utility model, such as Figure 9 As shown, a household appliance 400 is also proposed.

[0136] The household appliance 400 includes the washing pump assembly 300 in the above embodiments. Therefore, the household appliance 400 possesses all the technical effects of the washing pump assembly 300 in the above embodiments, which will not be repeated here.

[0137] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, unless otherwise expressly specified and limited. The terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0138] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0139] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0140] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A surge protection circuit, characterized in that, include: Differential-mode surge absorption circuit, including: Thermistor, connected to the live wire; The first varistor is connected to the thermistor and the neutral wire; Common-mode surge absorption circuit, including: Gas discharge tube; The second varistor is connected in series with the gas discharge tube between the live wire and the ground wire; The third varistor is connected in series with the gas discharge tube between the neutral line and the ground line.

2. The surge protection circuit according to claim 1, characterized in that, The first end of the gas discharge tube is connected to the ground wire; The first end of the second varistor is connected to the live wire, and the second end of the second varistor is connected to the second end of the gas discharge tube; The first end of the third varistor is connected to the neutral line, and the second end of the third varistor is connected to the second end of the gas discharge tube.

3. The surge protection circuit according to claim 1, characterized in that, The first end of the gas discharge tube is connected to the live wire and the neutral wire, respectively. The first end of the second varistor is connected to the ground wire, and the second end of the second varistor is connected to the second end of the gas discharge tube; The first end of the third varistor is connected to the ground wire, and the second end of the third varistor is connected to the second end of the gas discharge tube.

4. The surge protection circuit according to claim 2, characterized in that, Also includes: The first capacitor is connected in parallel with the first varistor; A common-mode inductor is connected in parallel with the first capacitor; The second capacitor is connected to the common-mode inductor and is connected between the live wire and the ground wire; The third capacitor is connected to the common-mode inductor and is connected between the neutral line and the ground line; Wherein, the thermistor, the common-mode inductor, the second varistor, and the gas discharge tube constitute the first common-mode surge absorption circuit; the thermistor, the common-mode inductor, the third varistor, and the gas discharge tube constitute the second common-mode surge absorption circuit.

5. A control device, characterized in that, include: The surge protection circuit as described in any one of claims 1 to 4 is connected to the power grid, and the surge protection circuit is used to suppress surge voltage between power grid conductors; A switching power supply, connected to the surge protection circuit and the load, is used to convert AC power input from the power grid into DC power for the load to use.

6. The control device according to claim 5, characterized in that, Also includes: An intelligent power module is connected to the switching power supply and the load, and the intelligent power module is used for power control of the load; A relay, connected to the switching power supply and the load, is used to control the on / off state of the load path.

7. The control device according to claim 5, characterized in that, The switching power supply includes: A rectifier and filter circuit is connected to the surge protection circuit. The rectifier and filter circuit is used to rectify and filter the AC power input from the power grid.

8. The control device according to claim 7, characterized in that, The rectifier filter circuit includes: The first diode is connected between the live wire and the ground terminal of the switching power supply; The second diode is connected between the fire wire and the general bus; The third diode is connected between the neutral wire and the general bus; The fourth diode is connected between the neutral wire and the ground terminal of the switching power supply; The fourth capacitor is connected between the general-purpose bus and the ground terminal of the switching power supply; An electrolytic capacitor is connected in parallel with the fourth capacitor; The thermistor and the first varistor in the surge protection circuit form a first differential-mode surge absorption circuit; the thermistor, the common-mode inductor in the surge protection circuit, and the electrolytic capacitor form a second differential-mode surge absorption circuit.

9. A washing pump assembly, characterized in that, include: The control device as described in any one of claims 5 to 8 is connected to the power grid; Pump body; The motor is connected to the control device and the pump body; The heating element is connected to the control device; The control device is used to control the operation of the motor and the heating tube, so that the motor drives the pump to draw in or output washing liquid, and the heating tube heats the washing liquid.

10. A household appliance, characterized in that, include: The washing pump assembly as described in claim 9.

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