Counter electromotive force absorption protection circuit and system of clothes airing machine

Abstract

The utility model discloses a clothes airing machine reverse electromotive force absorption protection circuit and system, the clothes airing machine reverse electromotive force absorption protection circuit comprises an isolation module and a first absorption module; the isolation module is connected with the first absorption module and the power supply module, is used for preventing reverse electromotive force from flowing back to a front-end power supply and at least comprises a first diode, the anode of the first diode is connected with the output end of the power supply module, and the cathode of the first diode is connected with the first absorption module; the first absorption module is connected with the isolation module and the motor driving module, is used for absorbing reverse electromotive force, and comprises a piezoresistor, a second electrolytic capacitor, a second capacitor and a second resistor; after the piezoresistor, the second electrolytic capacitor, the second capacitor and the second resistor are connected in parallel, one end is connected with the cathode of the first diode, and the other end is grounded; the anode of the second electrolytic capacitor is connected with the cathode of the first diode; the circuit has the advantages of effective absorption and isolation of the reverse electromotive force of the motor, simple circuit structure, strong applicability and low cost.

Description

Technical Field

[0001] The utility model relates to a lifting control circuit of a clothes dryer, in particular to a back electromotive force absorption protection circuit of a clothes dryer. When the lifting motor of the clothes dryer reverses or stops rotating, the circuit can absorb the back electromotive force to protect the front-end power supply and other components. Background Technique

[0002] The lifting of the drying rod assembly of an electric clothes dryer depends on the forward or reverse rotation of the lifting motor in the main machine, which drives the steel wire rope to pull the drying rod assembly up and down. When the lifting motor reverses (for example, from forward rotation to reverse rotation) or stops rotating, a back electromotive force much higher than the power supply voltage may be generated, which will have a certain impact on the front-end power supply and components of the circuit control system of the electric clothes dryer, and even cause damage to the front-end power supply and components.

[0003] At present, for the problem of the back electromotive force generated by the lifting motor of an electric clothes dryer, there are mainly two protection measures:

[0004] Software protection method: The main controller monitors the voltage across the motor in real time. Once the detected voltage exceeds the preset safety threshold, the software will immediately cut off the motor drive module to reduce the impact of the back electromotive force. However, this method has some limitations: it cannot actively consume the energy generated by the back electromotive force, and only reduces its impact by turning off the drive module. If it is turned off frequently, it may cause a greater impact on the drive switch device and the motor itself.

[0005] Hardware protection method: The voltage across the motor is monitored by a hardware comparator and compared with the preset safety voltage threshold. If the voltage exceeds the standard, the hardware will automatically cut off the motor drive module. This method also faces some problems: it is relatively complex to implement, relying on the motor drive module and the real-time monitoring system; it requires continuous power supply. If the control system is not powered on and the motor generates a back electromotive force due to external force, the existing technology cannot provide protection, which may cause irreversible damage to the control system.

[0006] For example, the invention patent with the application publication number CN107332482A discloses a noise reduction circuit and method applied to a clothes dryer. The circuit includes a power module, an MCU controller, a drive circuit, a relay and a motor. The MCU controller, the drive circuit, the relay and the motor are connected in sequence. The output end of the power module supplies voltage to the MCU controller and the relay respectively, and a voltage reduction circuit is also connected in the relay.

[0007] In summary, the existing back electromotive force protection technologies for the lifting motors of clothes dryers have some deficiencies, including the lack of an effective and safe energy discharge circuit, the complexity of implementation, and the lack of protection in the power-off state, etc. These all need to be improved and optimized in future designs. Summary of the Invention

[0008] In view of the problems existing in the back electromotive force protection technology of the lifting motor of the existing clothes dryer, such as the lack of an effective and safe energy discharge circuit, the complexity of implementation, and the insufficient protection in the power-off state, the technical problem to be solved by the present utility model is to provide a back electromotive force absorption protection circuit for a clothes dryer to absorb the back electromotive force generated by the lifting motor in real time with a simple circuit structure.

[0009] The technical solution adopted by the present utility model to solve the above technical problems is: a back electromotive force absorption protection circuit for a clothes dryer, including an isolation module and a first absorption module; the isolation module and the first absorption module are arranged between a power supply module and a motor drive module;

[0010] The isolation module is connected to the first absorption module and the power supply module, and is used to prevent the back electromotive force from flowing back to the front-end power supply, and at least includes a first diode. The positive electrode of the first diode is connected to the output end of the power supply module, and the negative electrode of the first diode is connected to the first absorption module;

[0011] The first absorption module is connected to the isolation module and the motor drive module, and is used to absorb the back electromotive force, and includes at least one varistor, a second electrolytic capacitor, a second capacitor and a second resistor; after the varistor, the second electrolytic capacitor, the second capacitor and the second resistor are connected in parallel, one end is connected to the negative electrode of the first diode, and the other end is grounded; the positive electrode of the second electrolytic capacitor is connected to the negative electrode of the first diode, and the negative electrode is grounded.

[0012] The preferred technical solution adopted by the present utility model to solve the above technical problems is: the isolation module further includes a first electrolytic capacitor, a first capacitor and a first resistor; after the first electrolytic capacitor, the first capacitor and the first resistor are connected in parallel, one end is connected to the positive electrode of the first diode, and the other end is grounded; the positive electrode of the first electrolytic capacitor is connected to the positive electrode of the first diode, and the negative electrode is grounded.

[0013] The preferred technical solution adopted by the present utility model to solve the above technical problems is: further includes a second absorption module; the second absorption module is connected to the lifting motor and the motor drive module, and is used to clamp the back electromotive force, and includes a third capacitor and a fourth resistor; after the third capacitor and the fourth resistor are connected in series, they are used to be connected in parallel between the lifting motor and the motor drive module.

[0014] The preferred technical solution adopted by the present utility model to solve the above technical problems is as follows: It further includes a third absorption module; the third absorption module is connected to the lifting motor and the motor drive module and is used to absorb the back electromotive force generated by the sudden power failure of the lifting motor, and includes a third resistor and a second diode; the third resistor and the positive electrode of the second diode are connected in series and then used to be connected in parallel between the lifting motor and the motor drive module.

[0015] The preferred technical solution adopted by the present utility model to solve the above technical problems is as follows: There are two varistors, including a first varistor and a second varistor, and the first varistor and the second varistor are connected in parallel with each other.

[0016] Another technical solution adopted by the present utility model to solve the above technical problems is as follows: A back electromotive force absorption protection circuit for a clothes dryer, including an isolation module and a first absorption module; the isolation module and the first absorption module are arranged between the power supply module and the motor drive module;

[0017] The isolation module is connected to the first absorption module and the power supply module and is used to prevent the back electromotive force from flowing back to the front-end power supply, and includes a first diode, a first electrolytic capacitor, a first capacitor and a first resistor; after the first electrolytic capacitor, the first capacitor and the first resistor are connected in parallel, one end is connected to the positive electrode of the first diode, and the other end is grounded; the positive electrode of the first electrolytic capacitor is connected to the positive electrode of the first diode, and the negative electrode is grounded; the negative electrode of the first diode is connected to the first absorption module;

[0018] The first absorption module is connected to the isolation module and the motor drive module and is used to absorb the back electromotive force, and includes at least one varistor, a second electrolytic capacitor, a second capacitor and a second resistor; after the varistor, the second electrolytic capacitor, the second capacitor and the second resistor are connected in parallel, one end is connected to the negative electrode of the first diode, and the other end is grounded; the positive electrode of the second electrolytic capacitor is connected to the negative electrode of the first diode, and the negative electrode is grounded.

[0019] The preference of another technical solution adopted by the present utility model to solve the above technical problems is as follows: It further includes a second absorption module; the second absorption module is connected to the lifting motor and the motor drive module and is used to clamp the back electromotive force, and includes a third capacitor and a fourth resistor; the third capacitor and the fourth resistor are connected in series and then used to be connected in parallel between the lifting motor and the motor drive module.

[0020] The preference of another technical solution adopted by the present utility model to solve the above technical problems is as follows: It further includes a third absorption module; the third absorption module is connected to the lifting motor and the motor drive module and is used to absorb the back electromotive force generated by the sudden power failure of the lifting motor, and includes a third resistor and a second diode; the third resistor and the positive electrode of the second diode are connected in series and then used to be connected in parallel between the lifting motor and the motor drive module.

[0021] Another preferred technical solution adopted by the present utility model to solve the above technical problems is as follows: There are two varistors, including a first varistor and a second varistor, and the first varistor and the second varistor are connected in parallel with each other.

[0022] Another technical solution adopted by the present utility model to solve the above technical problems is: a back electromotive force absorption protection circuit system for a clothes dryer, including a power supply module, a motor drive module, a lifting motor, and a back electromotive force absorption protection circuit for the clothes dryer; the motor drive module is connected to the lifting motor and is used to control the start, stop, forward and reverse rotation of the lifting motor;

[0023] The input end of the power supply module is used to connect to a power source, and the output end of the power supply module is connected to the isolation module; the isolation module is connected to the power supply module and the first absorption module, and the first absorption module is connected to the isolation module and the motor drive module.

[0024] Compared with the prior art, the advantages of the present utility model are: The first absorption module absorbs the back electromotive force generated by the lifting motor due to the external force acting on the motor during startup, commutation, stop, and when not powered on, and then the isolation module isolates and prevents the back electromotive force generated by the lifting motor from flowing back to the front-end power source, power supply module, or other functional modules, thereby forming a primary protection of direct absorption and a secondary protection of backup isolation, and reducing the negative impact of the back electromotive force of the lifting motor on the front-end power source and other components with two lines of defense. It not only overcomes the problems of the lack of an effective and safe energy discharge circuit, implementation complexity, and insufficient protection in the non-powered state in the prior art, but also has a simple circuit structure, strong applicability, reduced system cost, reduced vibration and noise during the operation of the lifting motor, and improved stability, reliability, and safety of the clothes dryer control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present utility model will be further described in detail below in conjunction with the drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are only drawn for the purpose of explaining the preferred embodiments and should not be used as a limitation to the scope of the present utility model. In addition, unless otherwise specified, the drawings only schematically show the composition or structure of the described object and may include exaggerated displays, and the drawings are not necessarily drawn to scale.

[0026] Figure 1 It is a system block diagram of the back electromotive force absorption protection circuit system for a clothes dryer;

[0027] Figure 2 It is the total circuit diagram of the back electromotive force absorption protection circuit system for a clothes dryer;

[0028] Figure 3 Circuit diagram of the isolation module and the first absorption module part

[0029] Figure 4 Circuit diagram of the lifting motor, the second absorption module, the third absorption module and the motor drive module part

[0030] Figure 5 Voltage waveforms of the system bus before and after adding the first absorption module

[0031] Figure 6 Voltage waveforms at both ends of the lifting motor before and after adding the second absorption module

[0032] Explanation of reference numerals

[0033] Back electromotive force absorption protection circuit system 200 of the clothes dryer, motor drive module 201, lifting motor 202, back electromotive force absorption protection circuit 100 of the clothes dryer, isolation module 101, first absorption module 102, second absorption module 103, third absorption module 104 Detailed implementation manners

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Those skilled in the art will appreciate that these descriptions are only descriptive and exemplary, and should not be construed as limiting the protection scope of the present invention

[0035] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. The terms "first" and "second" are only for descriptive convenience and have no other directional meaning, and should not be construed as limiting the present invention

[0036] As Figures 1 to 4 shown, the back electromotive force absorption protection circuit system 200 of the clothes dryer provided in this embodiment includes a power supply module (not shown in the circuit diagram), a motor drive module 201, a lifting motor 202, and the back electromotive force absorption protection circuit 100 of the clothes dryer provided in this embodiment

[0037] Among them, the input end of the power supply module is used to connect to a power source, and the output end supplies power to the motor drive module 201, the lifting motor 202, and other functional modules. The other functional modules usually also include a lighting module, a sterilization module, a drying module, etc. The motor drive module 201 is connected to the lifting motor 202 and is used to control the start, stop, forward and reverse rotation of the lifting motor 202.

[0038] In this embodiment, the motor drive module 201 includes a combination of two groups of relays and their contact switches K1 and K2, which are respectively used to control the forward start / stop and reverse start / stop of the lifting motor. The motor drive module 201 is connected to a sampling resistor R5, and the sampling resistor R5 is connected to the IO interface of the single-chip microcomputer chip for sampling the real-time current value of the operation of the lifting motor 202.

[0039] Such as Figure 2 and Figure 3 As shown, the back electromotive force absorption protection circuit 100 provided in this embodiment includes an isolation module 101 and a first absorption module 102. The isolation module 101 and the first absorption module 102 are arranged between the power supply module and the motor drive module 201.

[0040] Specifically, the isolation module 101 is connected to the first absorption module 102 and the power supply module. The other functional modules are also arranged at the front end of the isolation module 101 to prevent the back electromotive force generated by the lifting motor 202 from flowing back to the front-end power source, the power supply module or other functional modules. Compared with the absorption module directly used to absorb the back electromotive force, the isolation module 101 is an isolation backup protection, serving as a second line of defense to protect the power supply module, other functional modules and the front-end power source from the influence of the back electromotive force.

[0041] The isolation module 101 includes at least a first diode D1. The positive electrode of the first diode D1 is connected to the output end of the power supply module, and the negative electrode of the first diode D1 is connected to the first absorption module 102. Utilizing the unidirectional conduction characteristic of the first diode D1, it plays a role of electrical isolation and safety protection.

[0042] In this embodiment, the isolation module 101 further includes a first electrolytic capacitor AEC1, a first capacitor C1, and a first resistor R1. After the first electrolytic capacitor AEC1, the first capacitor C1, and the first resistor R1 are connected in parallel, one end is connected to the positive electrode of the first diode D1, and the other end is grounded to GND. Among them, the positive electrode of the first electrolytic capacitor AEC1 is connected to the positive electrode of the first diode D1, and the negative electrode is grounded to GND. The first electrolytic capacitor AEC1 and the first capacitor C1 form a filtering network, and its main function is to suppress the electromagnetic noise and clutter signals that may be input to the front-end power source, reducing the interference generated to the front-end power source.

[0043] The first absorption module 102 is connected to the isolation module 101 and the motor drive module 201, and is also connected to the system bus of the clothes dryer circuit, and is used for absorbing the back electromotive force. The first absorption module 102 can absorb the back electromotive force generated by the external force acting on the motor when the lifting motor 202 starts, stops, and is not powered on, so as to protect the power supply from surge impact.

[0044] Specifically, the first absorption module 102 includes at least one varistor, a second electrolytic capacitor AEC2, a second capacitor C2, and a second resistor R2. In this embodiment, preferably two varistors are provided, including a first varistor MOV1 and a second varistor MOV2, and the first varistor MOV1 and the second varistor MOV2 are connected in parallel with each other. After the two varistors MOV1, MOV2, the second electrolytic capacitor AEC2, the second capacitor C2, and the second resistor R2 are connected in parallel, one end is connected to the negative electrode of the first diode D1, and the other end is grounded to GND. Among them, the positive electrode of the second electrolytic capacitor AEC2 is connected to the negative electrode of the first diode D1, and the negative electrode is grounded to GND.

[0045] When the lifting motor 202 of the clothes dryer starts, stops, or is not powered on, the generated back electromotive force is superimposed on the system bus through the motor drive module 201, resulting in a transient high voltage on the system bus. At this time, the resistance values of the first varistor MOV1 and the second varistor MOV2 instantaneously decrease, enabling them to pass a large current, instantaneously absorbing the energy of the back electromotive force, and at the same time clamping the system bus voltage within the voltage range where the lifting motor 202 can operate reliably.

[0046] As Figure 5 shown are the voltage waveforms of the system bus before and after adding the first absorption module 102. Among them, the blue line L1 is the voltage waveform before absorption, and the brown line L2 is the voltage waveform after absorption.

[0047] It can be seen that for the back electromotive force absorption protection circuit and system of the clothes dryer provided by the present utility model, the first absorption module 102 absorbs the back electromotive force generated by the external force acting on the motor when the lifting motor 202 starts, commutes, stops, and is not powered on, and then the isolation module 101 isolates and prevents the back electromotive force generated by the lifting motor 202 from flowing back to the front-end power supply, power supply module, or other functional modules, thereby forming a primary protection of direct absorption and a secondary protection of backup isolation, and reducing the negative impact of the back electromotive force of the lifting motor 202 on the front-end power supply and other components with two lines of defense. It not only overcomes the problems in the prior art such as the lack of an effective and safe energy discharge circuit, the complexity of implementation, and the insufficient protection in the non-power state, but also has a simple circuit structure, strong applicability, reduced system cost, reduced vibration and noise during the operation of the lifting motor, and improved stability, reliability, and safety of the clothes dryer control system.

[0048] Further, as Figure 2 and Figure 3 shown, the back electromotive force absorption protection circuit 100 of the clothes dryer provided in this embodiment further includes a second absorption module 103. The second absorption module 103 is connected to the lifting motor 202 and the motor drive module 201, and is used to clamp the back electromotive force. The second absorption module 103 can absorb the peak voltage at both ends of the motor caused by the continuous friction between the carbon brush and the commutator inside the lifting motor 202, and at the same time clamp the back electromotive force.

[0049] Specifically, the second absorption module 103 includes a third capacitor CX1 and a fourth resistor R4. After the third capacitor CX1 and the fourth resistor R4 are connected in series, they are connected in parallel between the lifting motor 202 and the motor drive module 201.

[0050] When the clothes dryer is lifting or lowering, the carbon brush inside the lifting motor 202 continuously contacts and rubs against the commutator, and the air medium between the two is ionized by the back electromotive force to generate electric sparks. At this time, the second absorption module 103 clamps the back electromotive force induced in the lifting motor 202 during the current transient and absorbs the peak voltage at both ends of the motor. At the same time, it suppresses the impact on the components caused by the rate of increase of the bus voltage dv / dt in the circuit of the motor drive module 201, ensures the reliable control of the motor drive module 201, and improves the service life of the motor.

[0051] As Figure 6 shown, the voltage waveforms at both ends of the lifting motor 202 before and after adding the second absorption module 103 are shown. Among them, the red line L3 is the voltage waveform before absorption, and the black line L4 is the voltage waveform after absorption.

[0052] As Figure 2 and Figure 3 shown, the back electromotive force absorption protection circuit 100 of the clothes dryer provided in this embodiment further includes a third absorption module 104. The third absorption module 104 is connected to the lifting motor 202 and the motor drive module 201, and is used to absorb the back electromotive force generated when the lifting motor 202 suddenly loses power, especially the back electromotive force generated when the lifting motor 202 suddenly loses power during the process of driving the drying rod assembly to descend.

[0053] Specifically, the third absorption module 104 includes a third resistor R3 and a second diode D2. After the positive poles of the third resistor R3 and the second diode D2 are connected in series, they are connected in parallel between the lifting motor 202 and the motor drive module 201.

[0054] When the drying rod assembly of the drying machine suddenly loses power during the process of descending under load, according to the four-quadrant operation principle of the motor, at this time, the lifting motor 202 operates in the second quadrant and the fourth quadrant, and is in the power generation state. The generated back electromotive force will be superimposed on the bus voltage, causing overvoltage of the lifting motor 202 or the power supply, resulting in a sharp drop in the system reliability. At this time, the third resistor R3 and the second diode D2 of the third absorption module 104 provide an effective and safe energy discharge channel for the back electromotive force, and the third resistor R3 converts the back electromotive force from electrical energy into heat energy for consumption.

[0055] In this embodiment, the second absorption module 103 and the third absorption module 104 are both connected in parallel between the lifting motor 202 and the motor drive module 201. Therefore, in this embodiment, the three-stage absorption module ensures real-time and effective absorption and isolation of the back electromotive force generated when the drying rod assembly of the drying machine is lifted, stopped, or not powered on, and when the lifting motor 202 commutes or stops rotating, ensuring the stability, safety, and reliability of the entire drying machine control system.

[0056] It should be noted that similar reference numerals represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it may not be further defined and explained in subsequent drawings.

[0057] The above introduces the back electromotive force absorption protection circuit and system of the drying machine provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the present invention and its core idea. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. The reverse electromotive force absorption protection circuit of the clothes drying machine is characterized by: It includes an isolation module and a first absorption module; the isolation module and the first absorption module are arranged between the power supply module and the motor drive module; The isolation module is connected to the first absorption module and the power supply module, and is used to prevent the reverse electromotive force from flowing back to the front-end power supply, and at least includes a first diode, the positive electrode of the first diode is connected to the output end of the power supply module, and the negative electrode of the first diode is connected to the first absorption module; The first absorption module is connected to the isolation module and the motor drive module, and is used to absorb reverse electromotive force, and includes at least one varistor, a second electrolytic capacitor, a second capacitor and a second resistor; after the varistor, the second electrolytic capacitor, the second capacitor and the second resistor are connected in parallel, one end is connected to the cathode of the first diode, and the other end is grounded; the positive electrode of the second electrolytic capacitor is connected to the cathode of the first diode, and the cathode is grounded.

2. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 1, characterized in that: The isolation module also includes a first electrolytic capacitor, a first capacitor and a first resistor; after the first electrolytic capacitor, the first capacitor and the first resistor are connected in parallel, one end is connected to the positive electrode of the first diode and the other end is grounded; the positive electrode of the first electrolytic capacitor is connected to the positive electrode of the first diode and the negative electrode is grounded.

3. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 1, characterized in that: It also includes a second absorption module; the second absorption module is connected to the lifting motor and the motor drive module, and is used to clamp the reverse electromotive force, including a third capacitor and a fourth resistor; the third capacitor and the fourth resistor are connected in series and are used to be connected in parallel between the lifting motor and the motor drive module.

4. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 1, characterized in that: It also includes a third absorption module; the third absorption module is connected to the lifting motor and the motor drive module, and is used to absorb the reverse electromotive force generated by sudden power failure of the lifting motor, including a third resistor and a second diode; the third resistor and the positive electrode of the second diode are connected in series and used to be connected in parallel between the lifting motor and the motor drive module.

5. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 1, characterized in that: The varistor is provided with two, including a first varistor and a second varistor, and the first varistor and the second varistor are connected in parallel with each other.

6. The reverse electromotive force absorption protection circuit of the clothes drying machine is characterized by: It includes an isolation module and a first absorption module; the isolation module and the first absorption module are arranged between the power supply module and the motor drive module; The isolation module is connected to the first absorption module and the power supply module, and is used to prevent the reverse electromotive force from flowing back to the front-end power supply, and includes a first diode, a first electrolytic capacitor, a first capacitor and a first resistor; after the first electrolytic capacitor, the first capacitor and the first resistor are connected in parallel, one end is connected to the positive electrode of the first diode, and the other end is grounded; the positive electrode of the first electrolytic capacitor is connected to the positive electrode of the first diode, and the negative electrode is grounded; the negative electrode of the first diode is connected to the first absorption module; The first absorption module is connected to the isolation module and the motor drive module, and is used to absorb reverse electromotive force, and includes at least one varistor, a second electrolytic capacitor, a second capacitor and a second resistor; after the varistor, the second electrolytic capacitor, the second capacitor and the second resistor are connected in parallel, one end is connected to the cathode of the first diode, and the other end is grounded; the positive electrode of the second electrolytic capacitor is connected to the cathode of the first diode, and the cathode is grounded.

7. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 6, characterized in that: It also includes a second absorption module; the second absorption module is connected to the lifting motor and the motor drive module, and is used to clamp the reverse electromotive force, including a third capacitor and a fourth resistor; the third capacitor and the fourth resistor are connected in series and are used to be connected in parallel between the lifting motor and the motor drive module.

8. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 6, characterized in that: It also includes a third absorption module; the third absorption module is connected to the lifting motor and the motor drive module, and is used to absorb the reverse electromotive force generated by sudden power failure of the lifting motor, including a third resistor and a second diode; the third resistor and the positive electrode of the second diode are connected in series and used to be connected in parallel between the lifting motor and the motor drive module.

9. The reverse electromotive force absorption protection circuit for clothes drying machine according to claim 6, characterized in that: The varistor is provided with two, including a first varistor and a second varistor, and the first varistor and the second varistor are connected in parallel with each other.

10. A clothes drying machine reverse electromotive force absorption protection circuit system, characterized in that: It comprises a power supply module, a motor drive module, a lifting motor and a clothes drying machine reverse electromotive force absorption protection circuit as described in any one of claims 1 to 9; the motor drive module is connected to the lifting motor and is used to control the start, stop and forward and reverse rotation of the lifting motor; The input end of the power supply module is used to connect to the power supply, and the output end of the power supply module is connected to the isolation module; The isolation module is connected to the power supply module and the first absorption module, and the first absorption module is connected to the isolation module and the motor drive module.

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