A thermal protection circuit for a domestic appliance and a domestic appliance

Abstract

The application discloses a thermal protection circuit of a household device and the household device, relates to the technical field of thermal protection of household devices, and discloses the thermal protection circuit, which comprises a thermal induction module and a power assembly. The thermal induction module is connected in series with the power assembly. The thermal induction module senses the temperature of the power assembly. The resistance of the thermal induction module is directly proportional to the temperature. The thermal induction module of the application increases in resistance with the sensed temperature. The greater the resistance of the thermal induction module, the greater the voltage shared. In a high-voltage environment, the voltage is not applied to the power assembly, thereby reducing the probability of the power assembly entering a thermal protection state due to excessively high temperature.

Description

Technical Field

[0001] This invention belongs to the field of thermal protection technology for household appliances, specifically, it relates to a thermal protection circuit for household appliances and household appliances. Background Technology

[0002] Household appliances are typically designed with 220V as the center voltage. When the voltage supplied to household appliances is higher than 220V, the internal electronic components overheat because the voltage they bear is higher than the voltage required for their operation. When the heat accumulates inside and reaches a certain temperature, the appliance enters a thermal protection state and stops working.

[0003] As the user base of household appliances continues to grow, the operating conditions of these appliances are becoming increasingly complex. For example, some users operate their appliances in areas with solar photovoltaic power generation. When using solar photovoltaic power, the voltage supplied to household appliances by the grid can reach up to 280V under sufficient sunlight, while at night the voltage may drop to 220V. Under these circumstances, if users operate their appliances during the day, the appliances may overheat significantly, and there is even a possibility that they may frequently enter thermal protection mode.

[0004] To meet the voltage requirements of home appliances during the day, users can install voltage regulators in high-voltage environments to regulate the voltage supplied to the appliances. However, adding a voltage regulator increases the cost of using the appliances, and there are also certain safety risks associated with users installing voltage regulators themselves.

[0005] Therefore, how to automatically adjust the voltage supplied to household appliances is a problem that urgently needs to be solved. Summary of the Invention

[0006] In order to automatically adjust the voltage supplied to household appliances under high voltage conditions and reduce the probability of household appliances entering thermal protection state, the present invention provides a thermal protection circuit for household appliances and household appliances.

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows: The present invention provides a thermal protection circuit for household appliances, the thermal protection circuit including: a thermal sensing module and a power component, the thermal sensing module being connected in series with the power component, the thermal sensing module sensing the temperature of the power component, and the resistance of the thermal sensing module being proportional to the temperature.

[0008] By adopting the above technical solution, under high-voltage (greater than 220V) conditions, because the voltage acting on the power component is greater than the voltage required for its operation (usually set to 220V), the temperature of the power component rises during operation, and the thermal sensing module senses the temperature of the power component. As the temperature sensed by the thermal sensing module increases, the resistance of the thermal sensing module increases, and the voltage formed across the thermal sensing module also increases. That is, the thermal sensing module bears a larger share of the voltage, thereby preventing the power component from entering a thermal protection state under high-voltage conditions where the entire voltage acts on it.

[0009] In one possible implementation, a heat dissipation module is also included, which is connected in parallel with the thermal sensing module, and the heat dissipation end of the heat dissipation module acts on the power component.

[0010] In one possible implementation, the heat dissipation module includes at least a set of heat dissipation units, the heat dissipation capacity of which is proportional to the voltage across the thermal sensing module.

[0011] By adopting the above technical solution, at least one set of heat dissipation units is set up in parallel with the thermal sensing module, and the heat dissipation capacity of each set of heat dissipation units is proportional to the voltage across the thermal sensing module. As the voltage across the thermal sensing module increases, the heat dissipation capacity of the heat dissipation unit becomes stronger, thereby cooling the power component by the heat dissipation unit and further reducing the probability of the power component entering the thermal protection state.

[0012] In one possible implementation, when there are multiple sets of heat dissipation units, the multiple sets of heat dissipation units are arranged in parallel and each set of heat dissipation units has a unique corresponding minimum start-up voltage.

[0013] By adopting the above technical solution, multiple sets of heat dissipation units are connected in parallel, and each set of heat dissipation units has a unique corresponding minimum starting voltage. As the voltage across the thermal sensing module increases and reaches the minimum starting voltage of the heat dissipation unit, the corresponding heat dissipation unit is powered on and started, cooling the power component. Therefore, the higher the temperature of the power component, the higher the temperature sensed by the thermal sensing module, resulting in a higher voltage across the thermal sensing module. A higher voltage across the thermal sensing module activates more heat dissipation units, allowing multiple heat dissipation units to cool the power component simultaneously, further reducing the probability of the motor entering thermal protection mode.

[0014] In one possible implementation, the heat dissipation unit is a fan, which starts when the minimum start-up voltage is lower than the voltage across the thermal sensing module.

[0015] In one possible implementation, a filtering module is also included, which is connected in series with the power component.

[0016] By adopting the above technical solution, the filtering module is used to filter out harmonics, reduce the impact of harmonics on the power components, and ensure the safe and stable operation of the power components.

[0017] In one possible implementation, the system further includes an on / off control module and a cooling component. The on / off control module is connected in parallel with the thermal sensing module, and the on / off control module is used to drive the cooling component to cool the power component.

[0018] By adopting the above technical solution, the voltage on both ends of the thermal sensing module is applied to the on / off control module, so that the on / off control module is powered on and conducts. Then, the on / off control module drives the cooling component to cool the power component, further reducing the probability of the motor entering the thermal protection state.

[0019] In one possible implementation, the thermal sensing module obtains the temperature of the power component through thermal radiation or thermal conduction.

[0020] In one possible implementation, the thermal sensing module is a positive temperature coefficient thermistor.

[0021] The present invention also provides a household appliance that includes the above-described thermal protection circuit.

[0022] By adopting the above technical solution, under high-voltage conditions, the power components in household appliances experience a temperature increase because the voltage they bear is higher than the voltage required for their operation. A positive temperature coefficient (PTC) thermistor senses the temperature of the power component. As the temperature sensed by the PTC thermistor increases, its resistance increases, and simultaneously, the voltage across the PTC thermistor also increases, meaning it bears a larger voltage load. This prevents the entire voltage from acting on the power component under high-voltage conditions, thus preventing it from entering a thermal protection state. In other words, this invention reduces the probability of household appliances entering a thermal protection state.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0024] 1. In this invention, a positive temperature coefficient thermistor is connected in series with a power component. When the voltage applied to the power component exceeds the voltage required for its operation, the temperature of the power component rises, and the positive temperature coefficient thermistor senses the temperature of the power component. As the temperature sensed by the positive temperature coefficient thermistor increases, the resistance of the positive temperature coefficient thermistor increases, and at the same time, the voltage across the positive temperature coefficient thermistor also increases, that is, the voltage it bears is larger, thereby preventing the power component from entering a thermal protection state under high voltage conditions where the voltage is entirely applied to the power component.

[0025] 2. The present invention provides at least one set of heat dissipation units connected in parallel with a positive temperature coefficient thermistor, and the heat dissipation capacity of each set of heat dissipation units is proportional to the voltage across the positive temperature coefficient thermistor. As the voltage across the positive temperature coefficient thermistor increases, the heat dissipation capacity of the heat dissipation unit becomes stronger, thereby cooling the power component by the heat dissipation unit and further reducing the probability of the power component entering the thermal protection state.

[0026] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a schematic diagram of the structure of a household appliance according to the present invention;

[0029] Figure 2 This is a circuit diagram of an NPN transistor used in the on / off control module of a thermal protection circuit for a household appliance according to the present invention.

[0030] Figure 3 This is a circuit diagram of an NMOS transistor used in the on / off control module of a thermal protection circuit for a household appliance according to the present invention.

[0031] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the appendices in the embodiments of the present invention. Figure 1-3 The technical solutions in the embodiments are clearly and completely described below. The embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0033] In the description of this invention, it should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or device.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to 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 invention based on the specific circumstances.

[0035] In special areas with solar photovoltaic, wind power, and tidal power generation, the voltage supplied by the power grid to household appliances fluctuates significantly due to the influence of solar radiation intensity, wind intensity, and tidal range. Household appliances are typically designed with 220V as their core voltage. When the voltage supplied by the power grid exceeds 220V, the appliances experience excessive heat due to the higher voltage they require for operation. This is particularly noticeable with household appliances operating on fixed frequencies.

[0036] Household fixed-frequency appliances, including but not limited to fixed-frequency air conditioners, refrigerators, and washing machines, operate either at maximum power or completely shut down, lacking the flexibility to adjust in between. Therefore, under high-voltage conditions (above 220V), because these appliances still operate at a fixed frequency, the excessive voltage they bear causes their internal electronic components to overheat, triggering thermal protection and stopping operation. This state is referred to as thermal protection mode. In practical applications, frequent triggering of thermal protection can lead to excessive wear on internal components (such as compressors and evaporator motors), increasing the risk of equipment damage.

[0037] To reduce the probability of household appliances entering thermal protection mode, this invention provides a thermal protection circuit for household appliances. This circuit can be applied to ordinary household appliances such as air conditioners, refrigerators, ovens, washing machines, water heaters, dishwashers, televisions, and water dispensers, as well as household fixed-frequency appliances, to automatically adjust the voltage supplied to the appliances. Hereinafter, ordinary household appliances and household fixed-frequency appliances will be collectively referred to as household appliances.

[0038] Specifically, household appliances include, but are not limited to, power supply components, power components, cooling components, and thermal protection circuits. The power supply components, power components, and cooling components are either existing components within the household appliance or modules composed of multiple existing components. The power supply components primarily supply power to the power components, cooling components, and thermal protection circuits. The power components are the core components of the household appliance, determining its start-up and shutdown. For example, if the household appliance is an air conditioner, the power components include, but are not limited to, evaporator fans, compressor fans, and condenser fans; if the household appliance is a refrigerator, the power component can be a compressor motor; if the household appliance is a washing machine, the power components include, but are not limited to, direct drive motors, induction motors, and permanent magnet DC motors. For ease of explanation, the power components within household appliances will be referred to as motors below.

[0039] For household appliances with cooling functions, the components or combinations of components that primarily perform the cooling function are called cooling components. For example, in a refrigerator, the cooling components include, but are not limited to, a compressor, condenser, dryer filter, capillary tube, and evaporator. The compressor draws refrigerant from the evaporator to the condenser, compressing it into a high-temperature, high-pressure gas. The condenser exchanges heat between this high-temperature, high-pressure refrigerant gas and the external environment, dissipating heat from the refrigerator's interior. The dryer filter absorbs moisture and impurities from the refrigerant, while the capillary tube converts the high-temperature, high-pressure refrigerant liquid into a low-temperature, low-pressure wet vapor, which then vaporizes in the evaporator. In other words, the low-temperature, low-pressure refrigerant absorbs heat from the refrigerator's interior. In practical applications, cooling components can specifically cool the motor and also cool the interior space of the appliance, indirectly cooling the motor by lowering the internal temperature.

[0040] To better illustrate the working principle of thermal protection circuits for protecting household appliances, the following explanation uses a washing machine as an example.

[0041] The washing machine includes a housing and power supply components, a motor, a cooling component, and a thermal protection circuit disposed within the housing. It should be noted that the washing machine may also contain other components, but since this example does not alter the original components of the washing machine, it will not describe each of the original components in the washing machine in detail.

[0042] In this example, the power supply component includes a charging port and a power board. The charging port is connected to the mains power supply and is also connected to the power board. The mains power charges the power board through the charging port, and the power board, after being charged, supplies power to the motor and thermal protection circuit. To protect the power board, a fuse is installed between the charging port and the power board. When the voltage supplied by the mains exceeds the maximum voltage that the power board can withstand, the fuse heats up and melts, thereby severing the electrical connection between the charging port and the power board.

[0043] In this example, the cooling component can use the same power supply as the motor, i.e., both are powered by the power board. Alternatively, the cooling component can be powered by a separately set circuit board. This example does not restrict the power supply method of the cooling component; the actual settings of the washing machine shall prevail.

[0044] In this example, the thermal protection circuit includes a thermal sensing module, a heat dissipation module, and an on / off control module. The thermal sensing module is connected in series with the motor, while the heat dissipation module and the on / off control module are both connected in parallel with the thermal sensing module. Figures 1 to 3 In the diagram, thermal protection circuits are represented by dashed boxes A.

[0045] Specifically, the thermal sensing module can be placed close to the motor or in contact with the motor. The thermal sensing module is used to sense the motor's temperature. When the thermal sensing module is close to the motor, it obtains the motor's temperature through thermal radiation; when it is in contact with the motor, it obtains the motor's temperature through thermal conduction.

[0046] In this example, taking the contact configuration between the thermal sensing module and the motor as an example, the thermal sensing module and the motor housing are connected by either a fixed connection or a detachable connection. A fixed connection could involve bonding the thermal sensing module to the motor housing, or using an integrated design where the thermal sensing module and motor housing are fixed together. A detachable connection could involve mounting the thermal sensing module to the motor housing with screws, or creating a slot in the motor housing to engage the thermal sensing module. It should be noted that if the motor housing is made of insulating material, the thermal sensing module can sense the heat distributed across the housing, and the voltage on the thermal sensing module will not be transferred to the housing due to contact. In practical applications, this invention does not limit the specific connection method used between the thermal sensing module and the motor, as long as it ensures that the thermal sensing module can obtain the motor's temperature.

[0047] The thermal sensing module is a device whose resistance increases as the acquired temperature rises; in this example, a positive temperature coefficient thermistor is preferred. Figure 2 and Figure 3 A positive temperature coefficient thermistor is denoted by R0. Therefore, under high voltage conditions, because the voltage supplied to the motor by the power board is greater than the voltage required for its operation, the motor temperature rises. The positive temperature coefficient thermistor R0 senses the motor temperature, and as the sensed temperature increases, the resistance of the positive temperature coefficient thermistor R0 increases, resulting in a larger voltage across its terminals. This allows it to handle a larger voltage load, preventing the entire voltage from acting on the motor under high voltage conditions and causing it to enter a thermal protection state.

[0048] The heat dissipation end of the heat dissipation module acts on the motor, and the heat dissipation module is mainly used to cool the motor. Specifically, the heat dissipation module includes at least one set of heat dissipation units. The heat dissipation capacity of the heat dissipation unit is directly proportional to the voltage across the positive temperature coefficient thermistor R0. That is, the higher the temperature sensed by the positive temperature coefficient thermistor R0 and the greater the voltage formed across its terminals, the better the cooling effect of the heat dissipation unit.

[0049] Cooling units, such as fans and negative pressure fans, are electronic devices that exchange air in the space where the motor is located, thereby cooling the motor. Since there are various types of fans, and different types of fans offer a variety of options in terms of size and minimum starting voltage, a fan is preferred as the cooling unit in this example. The size of the fan can be selected according to the size of the space where the motor is located. The fan can be installed inside the washing machine using a fixed or detachable connection method, with the air outlet facing the motor. In this case, the fan outlet serves as the heat dissipation end of the cooling module, blowing air through the outlet to the motor to remove heat and achieve the purpose of cooling the motor.

[0050] It should be noted that the minimum starting voltage of a fan refers to the minimum voltage required for the fan to start working.

[0051] In a specific example, when the heat dissipation module includes only one set of heat dissipation units, that is, when the heat dissipation module contains only one fan, the fan motor is set to an inverter fan motor and the minimum starting voltage v1 of the fan is: v1 = γ1w0, where v1 > 0, and γ1 is the conversion factor. v0 is the total voltage provided by the power board, v f This is the first voltage that the motor can withstand. This first voltage is higher than the motor's minimum starting voltage but lower than its maximum withstand voltage. The minimum starting voltage is the minimum voltage required for the motor to start operating, and the maximum withstand voltage is the critical voltage before the motor enters thermal protection mode. In this example, the first voltage is v. f The voltage value should be slightly higher than 220V. The fluctuation range can be designed according to the actual voltage that the motor can withstand. For example, the motor operates normally between 220V and 222V. Above 222V, the heating efficiency increases, so v f It can be set to a value between 220V and 222V. w0 is the value of the motor at the first voltage v. f The temperature value sensed by the positive temperature coefficient thermistor R0.

[0052] Therefore, as the voltage across the positive temperature coefficient thermistor R0 increases and reaches the fan's minimum starting voltage v1, the fan powers on and starts, blowing air through the outlet to cool the motor. Furthermore, if the temperature sensed by the positive temperature coefficient thermistor R0 continues to rise, the voltage across it continues to increase. The higher the voltage received by the fan, the faster the variable frequency fan motor rotates, the greater the airflow speed through the outlet, and the better the cooling effect on the motor.

[0053] In another specific example, when the heat dissipation module includes multiple heat dissipation units, i.e., the heat dissipation module contains multiple fans, the multiple fans are connected in parallel, and each fan has a unique corresponding minimum start-up voltage. In this case, the minimum start-up voltage of the multiple fans is a multiple of the minimum start-up voltage v1 of a single fan, with a maximum multiple not exceeding 1. For example, if there are three fans, the minimum start-up voltage of the first fan is... The minimum starting voltage for the second fan is The minimum starting voltage for the third fan is V1.

[0054] Therefore, as the voltage across the positive temperature coefficient thermistor R0 increases and reaches the minimum starting voltage of any given fan, that fan powers on and starts, cooling the motor by blowing air through it. Furthermore, if the temperature sensed by the positive temperature coefficient thermistor R0 continues to rise, the voltage across it increases, and the number of times the voltage exceeds the minimum starting voltage increases. This results in more fans being activated, and with multiple fans simultaneously cooling the motor, the cooling effect is better.

[0055] For cooling modules that include multiple fans, all fans can be either variable frequency (VFD) or fixed frequency (FFM) motors. A FFM motor's speed does not increase with the voltage across the positive temperature coefficient (PTC) thermistor R0. Alternatively, some fans can be VFD motors, while the rest can be FFM motors; the choice depends on the specific needs.

[0056] In this example, a filter module is also configured for the motor. The filter module is connected in series with the motor. The filter module can be placed between the motor and the positive temperature coefficient thermistor R0, or it can be placed on the side of the motor away from the positive temperature coefficient thermistor R0. This example uses the case where the filter module is placed between the motor and the positive temperature coefficient thermistor R0. Specifically, the filter module includes a capacitor and an inductor. Figure 2 and Figure 3In this circuit, C and L represent capacitor and inductor, respectively. The capacitor C and inductor L are connected in series. The filter module formed by the series connection of capacitor C and inductor L filters out harmonics in the circuit to ensure the safe and stable operation of the motor.

[0057] The on / off control module is located between the cooling component and the module that supplies power to the cooling component. The on / off control module is mainly used as an electrical switch to drive the cooling component to start. Figures 1 to 3 Taking the power supply board supplying power to the cooling component as an example, the on / off control module is located between the cooling component and the power supply board. It should be noted that the power supply line from the power supply board to the cooling component is isolated from the power supply line from the power supply board to the motor; that is, the cooling component and the motor are not connected in either series or parallel.

[0058] In a specific example, the on / off control module includes a first resistor, a Zener diode, and an electrical switch. Figure 2 The components are represented by R1, Z, and Q1. The negative terminal of the Zener diode Z is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to one end of the positive temperature coefficient thermistor R0, and the other end of the positive temperature coefficient thermistor R0 is connected to the positive terminal of the Zener diode Z. In this example, the electrical switch Q1 is an NPN transistor. The base of the NPN transistor is connected to the common terminal of the Zener diode Z and the first resistor R1, and the collector of the NPN transistor is connected to the power supply board. The emitter of the NPN transistor is connected to the cooling assembly.

[0059] The set voltage v2 of the Zener diode Z mentioned above is: v2 = γ2w1, where v2 > 0, and γ2 is the conversion factor. v0 is the total voltage provided by the power board, v s This is the maximum voltage that the motor can withstand; in this example, v s For voltage values ​​greater than 220V, the fluctuation range can be designed according to the actual voltage that the motor can withstand. For example, the motor is prone to triggering thermal protection between 230V and 235V. f It can be set to a value between 230V and 235V. w1 is the maximum voltage the motor can withstand. s The temperature value sensed by the positive temperature coefficient thermistor R0.

[0060] Therefore, after the fan is turned on, if the motor temperature continues to rise, the temperature sensed by the positive temperature coefficient thermistor R0 will increase. As the temperature rises, the resistance increases, resulting in a larger voltage across the positive temperature coefficient thermistor R0. When the voltage reaches the set voltage v2 of the Zener diode Z, the Zener diode Z conducts, providing a high-level signal to the base of the NPN transistor. This causes the collector and emitter of the NPN transistor to conduct, enabling the power board to supply power to the cooling component. The cooling component then powers on and starts. At this point, the cooling component and the fan simultaneously dissipate heat from the motor, further reducing its temperature.

[0061] In another specific example, the on / off control module includes a second resistor and an NMOS transistor. Figure 3 R2 and Q2 are used to represent the components respectively. The NMOS transistor Q2 is positioned between the power supply board and the cooling component. Specifically, the gate of the NMOS transistor Q2 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to one end of the positive temperature coefficient thermistor R0. The source of the NMOS transistor Q2 is connected to the power supply board, and the drain of the NMOS transistor Q2 is connected to the cooling component.

[0062] It should be noted that the gate turn-on voltage v3 of NMOS transistor Q2 is the same as the set voltage v2 of Zener diode Z, that is, v3 = v2. The gate turn-on voltage v3 of NMOS transistor Q2 means that when the voltage applied to the gate of NMOS transistor Q2 reaches v3, NMOS transistor Q2 turns on; the set voltage v2 of Zener diode Z means that when the voltage applied to the negative terminal of Zener diode Z reaches v2, Zener diode Z turns on.

[0063] Therefore, after the fan is turned on, if the motor temperature continues to rise, the temperature sensed by the positive temperature coefficient thermistor R0 will be higher. As the temperature rises, the resistance increases, and thus the voltage across the positive temperature coefficient thermistor R0 will be greater. When the voltage reaches the gate turn-on voltage v3 of the NMOS transistor Q2, the NMOS transistor Q2 turns on, causing the power board to supply power to the cooling component. The cooling component is then powered on and started, allowing the cooling component and the fan to simultaneously dissipate heat from the motor, further reducing the motor temperature.

[0064] In summary, the working process of the thermal protection circuit for a household appliance according to an embodiment of the present invention is as follows: The power board supplies power to the motor and the positive temperature coefficient thermistor R0. When the voltage applied to the motor is higher than the voltage required for the motor to operate, the motor temperature rises. The positive temperature coefficient thermistor R0 senses the temperature of the motor. The resistance of the positive temperature coefficient thermistor R0 increases as the sensed temperature rises. As the resistance of the positive temperature coefficient thermistor R0 increases, the voltage formed across the positive temperature coefficient thermistor R0 increases, and thus the voltage it bears increases. When the voltage across the positive temperature coefficient thermistor R0 reaches the minimum starting voltage of the fan, the fan powers on and starts, at which point the fan blows air to cool the motor. As the voltage applied to the motor continues to rise, the temperature sensed by the positive temperature coefficient thermistor R0 continues to rise, its resistance continues to increase, and the voltage it shares increases. When the voltage across the positive temperature coefficient thermistor R0 reaches the set voltage of the Zener diode Z or the turn-on voltage of the NMOS transistor, the Zener diode drives the NPN transistor to turn on the power board and the cooling component, or the NMOS transistor turns on the power board and the cooling component, and the power board supplies power to the cooling component, so that the heat dissipation module and the cooling component simultaneously cool the motor, reducing the probability of the motor entering the thermal protection state.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A thermal protection circuit for a household appliance, characterized in that, include: A thermal sensing module and a power component are provided, wherein the thermal sensing module is connected in series with the power component, the thermal sensing module senses the temperature of the power component, and the resistance of the thermal sensing module is proportional to the temperature.

2. The thermal protection circuit for household appliances according to claim 1, characterized in that, It also includes a heat dissipation module, which is connected in parallel with the thermal sensing module, and the heat dissipation end of the heat dissipation module acts on the power component.

3. The thermal protection circuit for household appliances according to claim 2, characterized in that, The heat dissipation module includes at least one set of heat dissipation units, and the heat dissipation capacity of the heat dissipation units is proportional to the voltage across the thermal sensing module.

4. The thermal protection circuit for household appliances according to claim 3, characterized in that, When there are multiple sets of the heat dissipation units, the multiple sets of heat dissipation units are arranged in parallel and each set of heat dissipation units has a unique corresponding minimum start-up voltage.

5. The thermal protection circuit for household appliances according to any one of claims 3-4, characterized in that, The heat dissipation unit is a fan, which starts when the minimum starting voltage is lower than the voltage across the thermal sensing module.

6. The thermal protection circuit for household appliances according to any one of claims 1-4, characterized in that, It also includes a filtering module, which is connected in series with the power component.

7. The thermal protection circuit for household appliances according to claims 1-4, characterized in that, It also includes an on / off control module and a cooling component. The on / off control module is connected in parallel with the thermal sensing module. The on / off control module is used to drive the cooling component to cool the power component.

8. The thermal protection circuit for household appliances according to claim 1, characterized in that, The thermal sensing module obtains the temperature of the power component through thermal radiation or thermal conduction.

9. The thermal protection circuit for household appliances according to claim 1, characterized in that, The thermal sensing module is a positive temperature coefficient thermistor.

10. A household appliance, characterized in that, The thermal protection circuit includes any one of claims 1-9.

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