A pmsm motor back emf non-isolated detection method and system

Abstract

The application provides a pulsator fixed-frequency washing machine motor back electromotive force non-isolation detection method and system, and relates to the household appliance control field, and the method steps are as follows: step S1, the common end of the motor is electrically connected with the first pole of the single-phase alternating current power supply, and the positive rotation end and the reverse rotation end of the motor are both electrically connected with the second pole of the single-phase alternating current power supply; step S2, the power supply ground VSS of the microcontroller MCU is electrically connected with the first pole of the single-phase alternating current power supply; step S3, during the power-off period of the motor, the voltage between the common end and the positive rotation end of the motor or the voltage between the common end and the reverse rotation end of the motor is detected through the microcontroller MCU, and the back electromotive force signal is obtained. The application has extremely low cost, high reliability, high detection precision and flexible control.

Description

Technical Field

[0001] This invention relates to the field of household appliance control, and more specifically, to a non-isolated detection method and system for the back electromotive force of a pulsator fixed-frequency washing machine motor. Background Technology

[0002] Top-loading washing machines with fixed frequency still hold a significant market share due to their simple structure, reliable control, and low cost. Their core washing motor typically uses a single-phase capacitor-driven asynchronous motor, characterized by high starting torque and high efficiency. The motor achieves forward or reverse rotation by controlling the power supply between the forward winding (forward rotation terminal) and the common terminal, thereby driving the pulsator for washing and rinsing. In addition to the washing motor, the washing machine's control system usually includes electromagnetic actuators such as inlet valves, drain valves, and actuators, all of which operate under high-voltage conditions. Measuring the motor's back electromotive force (EMF) has extremely important engineering value. First, the waveform frequency of the back EMF is proportional to the motor speed. Measuring the frequency of the back EMF allows for accurate weighing of the spin-drying load, thus optimizing water consumption and washing time. Second, during high-speed spin-drying, uneven distribution of clothes can cause drum eccentricity, leading to severe vibration. Analyzing the amplitude fluctuations of the back EMF allows for high-precision eccentricity detection, enabling timely alarms or speed adjustments, improving safety and user experience. In addition, the amplitude of the back electromotive force indirectly reflects the fluctuation of the power supply voltage and can be used to realize overvoltage protection of the input power supply.

[0003] Existing methods for detecting back EMF in washing machine motors generally use optocoupler isolation circuits. All motor control thyristors and high-voltage load control thyristors are driven in isolation using optocouplers. In this case, the primary side of the optocoupler uses the low-voltage power supply from the MCU side, while the secondary side uses another isolated high-voltage floating power supply. This allows the back EMF detection circuit to be directly connected between the motor's reverse terminal and the common terminal without interfering with the control circuit. However, this approach requires an additional optocoupler isolation circuit for each additional high-voltage load, significantly increasing cost and complicating circuit board layout. Reliability also decreases with the increased number of optocouplers. Alternatively, a hybrid control scheme can be used. This involves using optocoupler isolation only for the motor control thyristors, while some high-voltage loads are controlled non-isolated, eliminating the corresponding optocouplers. While this reduces cost to some extent, it still retains multiple optocouplers and has complex control logic, failing to resolve the cost and reliability issues. Summary of the Invention

[0004] The present invention aims to solve the problems of significantly increased cost, complex circuit board layout, complex control logic, and poor reliability of the back EMF detection method for washing machine motors.

[0005] To address the aforementioned problems, this invention provides a non-isolated method and system for detecting the back electromotive force of a pulsator-driven fixed-frequency washing machine motor. The washing machine's power supply terminal is connected to a single-phase AC power supply, the connection terminal of which includes a first pole and a second pole. The washing machine motor has a common terminal, a forward rotation terminal, and a reverse rotation terminal. The method steps are as follows: Step S1: Wiring the motor. The common terminal of the motor is connected to the first pole of the single-phase AC power supply, and the forward and reverse terminals of the motor are connected to the second pole of the single-phase AC power supply. The forward and reverse terminals of the motor are connected to the signal control terminal of the microcontroller (MCU) through the motor control unit. Step S2: Wiring the microcontroller MCU. Connect the power ground VSS of the internal microcontroller MCU of the washing machine to the first pole of the single-phase AC power supply. Step S3: Back EMF detection. During the motor power-off period, the back EMF signal is obtained by detecting the voltage between the motor common terminal and the forward rotation terminal, or the voltage between the motor common terminal and the reverse rotation terminal, through the microcontroller (MCU).

[0006] The present invention provides a non-isolated detection method and system for the back electromotive force of a pulsator fixed-frequency washing machine motor, which, compared with the prior art, has the following beneficial effects, but is not limited to: In this invention, the common terminal of the motor and the power ground VSS of the microcontroller MCU are both electrically connected to the first pole, ensuring that both the motor and the microcontroller MCU are powered by a single-phase AC power supply; the second pole is used as the common terminal of at least some other electrical components of the washing machine; the MCU controls the output of the second pole to selectively connect the second pole to the forward or reverse rotation terminal of the motor, thereby realizing forward or reverse rotation of the motor; the MCU controls the output of the first pole to selectively connect the first pole to the other electrical components, thereby realizing control of the other electrical components; during the motor power-off period, the MCU detects the voltage between the common terminal and the forward rotation terminal of the motor, or detects the voltage between the common terminal and the reverse rotation terminal of the motor, to obtain a back EMF signal, thereby realizing non-isolated back EMF detection.

[0007] This invention has extremely low cost: it reduces all optocoupler isolation devices used for motor control and high-voltage load control, and there is no need to add any isolation components for back EMF detection. It only uses ordinary resistors, capacitors and a low-cost operational amplifier, and can even utilize the operational amplifier built into the MCU, resulting in a significant reduction in hardware cost.

[0008] This invention offers high reliability: it reduces the number of components such as optocouplers that are prone to aging and temperature fluctuations, simplifies circuit board layout, and improves the long-term operational reliability of the system in harsh environments such as humidity and high temperature.

[0009] This invention offers high detection accuracy: Since the detection signal shares a common ground with the MCU, it can be directly sampled using the MCU's internal high-precision ADC. Combined with the operational amplifier conditioning circuit, it can accurately and faithfully reproduce the waveform of the back electromotive force, thereby achieving precise weighing, high-precision eccentricity detection, and reliable overvoltage protection.

[0010] This invention offers flexible control: the MCU can directly and quickly drive all thyristors without the need for optocoupler transmission delay, resulting in faster control response.

[0011] This invention is easy to implement: the whole solution has low requirements for MCU resources, the algorithm is simple, and it is easy to promote on the existing low-cost pulsator washing machine main control board.

[0012] Furthermore, the motor power-off period in step S3 specifically refers to the time period after the microcontroller MCU shuts off power to the forward or reverse end of the motor; In step S3, the voltage detection is specifically performed by the analog-to-digital converter of the microcontroller MCU.

[0013] Furthermore, it also includes step S4, wiring of other loads, one end of other loads in the washing machine is connected to the common terminal of the motor, and the other end of other loads is electrically connected to the second pole of the single-phase AC power supply; the control terminal of other loads is connected to the signal control terminal of the microcontroller MCU.

[0014] A non-isolated back EMF detection system for a pulsator fixed-frequency washing machine motor is characterized by comprising a single-phase AC power supply, a motor, a microcontroller (MCU), a motor control unit, and a voltage detection unit. Both the forward and reverse ends of the motor are electrically connected to the second pole of the single-phase AC power supply and the signal control terminal of the microcontroller (MCU) through the motor control unit. The motor control unit is used to control the forward and reverse rotation of the motor. The common terminal of the motor and the VSS terminal of the microcontroller MCU are both electrically connected to the first pole of the single-phase AC power supply. The common terminal of the motor is connected to the signal detection terminal of the microcontroller MCU through a voltage detection unit. The voltage detection unit is used to detect the voltage of the forward or reverse terminal relative to VSS during the power-off period of the motor to obtain the back EMF signal.

[0015] Furthermore, the common terminal of the motor is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply. The switching control terminals of other loads are connected to the signal control terminals of the microcontroller (MCU) through the load control unit.

[0016] Furthermore, the first pole of the single-phase AC power supply is the neutral wire, and the second pole is the live wire; or, the first pole of the single-phase AC power supply is the live wire, and the second pole is the neutral wire.

[0017] Furthermore, the VSS terminal of the microcontroller MCU is electrically connected to the first pole of a single-phase AC power supply through a resistor.

[0018] Furthermore, the other loads include at least one of an inlet valve, a drain valve, a traction device, and a heater.

[0019] Furthermore, the motor control unit includes a control switch and a signal control module. The forward and reverse ends of the motor are connected to the second pole of a single-phase AC power supply through different control switches. The control terminal of the control switch is electrically connected to the signal control terminal of the microcontroller (MCU) through the signal control module.

[0020] Furthermore, the control switches in the motor control unit include thyristor TR1 and thyristor TR2; the signal control module includes optocoupler PH1 and optocoupler PH2. The forward rotation end of the motor is connected to the T2 end of the thyristor TR1, and the T1 end of the thyristor TR1 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR1 is connected in series with capacitor C1, resistor R1, and the T1 terminal of the thyristor TR1 in sequence. The control terminal G of the thyristor TR1 is connected to one end of resistor R2 and one end of resistor R10. The other end of resistor R10 is connected to the second pole of a single-phase AC power supply; A capacitor C6 is connected in parallel across the two ends of resistor R10; The other end of resistor R2 is connected to the collector of optocoupler PH1, and the emitter of optocoupler PH1 is grounded; The anode of optocoupler PH1 is connected to the DJ+ pin of the microcontroller MCU through a control circuit; The cathode of optocoupler PH1 is connected to the VSS pin of the microcontroller MCU; The reverse end of the motor is connected to the T2 terminal of the thyristor TR2, and the T1 terminal of the thyristor TR2 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR2 is connected in series with the capacitor C3, the resistor R4, and the T1 terminal of the thyristor TR2. The control terminal G of the thyristor TR2 is connected to one end of resistor R3 and one end of resistor R6. The other end of resistor R3 is connected to the second pole of a single-phase AC power supply; A capacitor C2 is connected in parallel across the two ends of resistor R3; The other end of resistor R6 is connected to the collector of optocoupler PH2, and the emitter of optocoupler PH2 is grounded; The anode of optocoupler PH2 is connected to the DJ pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH2 is connected to the VSS pin of the microcontroller MCU; An inductor and a capacitor C5 are connected in parallel between the forward and reverse ends of the motor.

[0021] Furthermore, the voltage detection unit includes a voltage divider resistor network and a bias circuit; the bias circuit includes an operational amplifier, the common terminal and the reverse terminal of the motor are connected to the voltage divider resistor network, the sampling point of the voltage divider resistor network is connected to the input terminal of the operational amplifier in the bias circuit, and the output terminal of the operational amplifier is connected to the analog-to-digital converter pin in the microcontroller MCU.

[0022] Furthermore, the voltage detection unit includes a voltage divider resistor network comprising resistors R8, R5, Rn, and R7, with the two ends of resistor R7 serving as sampling points for the voltage divider resistor network; the bias circuit includes an operational amplifier, resistors R11, R12, and R13, and capacitor C4, all housed within the microcontroller MCU. The reverse end of the motor is connected in series with resistors R8, R5, Rn, R7, and the common end of the motor. The common end of the motor is connected to the VSS pin of the microcontroller MCU. The connection point between resistor R7 and the common terminal of the motor is connected to one end of resistor R11. The other end of resistor R11 is simultaneously connected to one end of resistor R12 and the positive input terminal P+ pin of the operational amplifier in the microcontroller MCU. The other end of resistor R12 is connected to the VDD pin of the microcontroller MCU. A capacitor C4 is connected in parallel across resistor R11; The connection point between resistors Rn and R7 is connected to one end of resistor R13, and the other end of resistor R13 is connected to the negative input P-pin of the operational amplifier in the microcontroller MCU.

[0023] Furthermore, the load control unit includes a silicon controlled rectifier (SCR) TR3; One end of the thyristor TR3 is connected to the common terminal of the motor, and the other end of the thyristor TR3 is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply; the control terminal of the thyristor TR3 is connected to the CTR-TR3 pin of the microcontroller MCU through a control circuit.

[0024] Furthermore, the load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 and thyristor TRn is connected to the common terminal of the motor, and the other end of the thyristor TR4 and thyristor TRn is connected to one end of different other loads respectively. The other end of the different other loads is connected to the second pole of the single-phase AC power supply. The control terminals of the thyristor TR4 and thyristor TRn are connected to the CTR-TR4 pin and CTR-TRn pin of the microcontroller MCU respectively through the control circuit. In the thyristor TRn, n is an integer greater than 4.

[0025] Furthermore, the load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TR4 is connected to one end of another load, which in turn is connected to the common terminal of the motor. The control terminal of the thyristor TR4 is connected to the collector of the optocoupler PH4 through resistor R15, and the emitter of the optocoupler PH4 is grounded. A resistor R18 is connected in parallel directly between the control terminal of the thyristor TR4 and the second pole of the single-phase AC power supply, and a capacitor C9 is connected in parallel across the two ends of the resistor R15. The anode of optocoupler PH4 is connected to the CTR-TR4 pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH4 is connected to the VSS pin of the microcontroller MCU; One end of the thyristor TRn is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TRn is connected to one end of another load, and the other end of the other load is connected to the common terminal of the motor. The control terminal of the thyristor TRn is connected to the collector of the optocoupler PHn through resistor R9, and the emitter of the optocoupler PHn is grounded; A resistor R17 is directly connected in parallel with the control terminal of the thyristor TRn and the second pole of the single-phase AC power supply. A capacitor C8 is connected in parallel across the two ends of the resistor R17. The anode of the optocoupler PHn is connected to the CTR-TRn pin of the microcontroller MCU via a control circuit; The cathode of the optocoupler PHn is connected to the VSS pin of the microcontroller MCU; where n in the thyristor TRn is an integer greater than 4. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the circuit structure of the back EMF detection system for the motor of a pulsator-driven fixed-frequency washing machine according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 3 of the present invention; Figure 5 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 4 of the present invention; Figure 6 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 5 of the present invention; Figure 7 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment Six of the present invention; Figure 8 This is a schematic diagram of the circuit wiring of the detection system according to Embodiment 7 of the present invention; Figure 9 This is a schematic diagram of the circuit wiring of the detection system in Embodiment 8 of the present invention; Figure 10 This is a schematic diagram of the circuit wiring of the detection system in Embodiment 9 of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0032] See Figure 1 This invention discloses a non-isolated method for detecting the back electromotive force of a pulsator-driven fixed-frequency washing machine motor. The washing machine's power supply terminal is connected to a single-phase AC power supply, the single-phase AC power supply connection terminal including a first pole and a second pole, and the washing machine motor having a common terminal, a forward rotation terminal, and a reverse rotation terminal. The method steps are as follows: Step S1: Wiring the motor. The common terminal of the motor is connected to the first pole of the single-phase AC power supply, and the forward and reverse terminals of the motor are connected to the second pole of the single-phase AC power supply. The forward and reverse terminals of the motor are connected to the signal control terminal of the microcontroller (MCU) through the motor control unit. Step S2: Wiring the microcontroller MCU. Connect the power ground VSS of the internal microcontroller MCU of the washing machine to the first pole of the single-phase AC power supply. Step S3: Back EMF detection. During the motor power-off period, the back EMF signal is obtained by detecting the voltage between the motor common terminal and the forward rotation terminal, or the voltage between the motor common terminal and the reverse rotation terminal, through the microcontroller (MCU).

[0033] In this invention, the common terminal of the motor and the power ground VSS of the microcontroller MCU are both electrically connected to the first pole, ensuring that both the motor and the microcontroller MCU are powered by a single-phase AC power supply; the second pole is used as the common terminal of at least some other electrical components of the washing machine; the MCU controls the output of the second pole to selectively connect the second pole to the forward or reverse rotation terminal of the motor, thereby realizing the forward or reverse rotation of the motor; during the motor power-off period, the MCU detects the voltage between the common terminal and the forward rotation terminal of the motor, or detects the voltage between the common terminal and the reverse rotation terminal of the motor, to obtain a back EMF signal, thereby realizing non-isolated back EMF detection.

[0034] This invention has extremely low cost: it eliminates all optocoupler isolation devices used for motor control and high-voltage load control, and there is no need to add any isolation components for back EMF detection. It only uses ordinary resistors, capacitors and a low-cost operational amplifier, and can even utilize the operational amplifier built into the MCU, resulting in a significant reduction in hardware costs.

[0035] This invention offers high reliability: it reduces the number of components such as optocouplers that are prone to aging and temperature fluctuations, simplifies circuit board layout, and improves the long-term operational reliability of the system in harsh environments such as humidity and high temperature.

[0036] This invention offers high detection accuracy: Since the detection signal shares a common ground with the MCU, it can be directly sampled using the MCU's internal high-precision ADC. Combined with the operational amplifier conditioning circuit, it can accurately and faithfully reproduce the waveform of the back electromotive force, thereby achieving precise weighing, high-precision eccentricity detection, and reliable overvoltage protection.

[0037] This invention offers flexible control: the MCU can directly and quickly drive all thyristors without the need for optocoupler transmission delay, resulting in faster control response.

[0038] This invention is easy to implement: the whole solution has low requirements for MCU resources, the algorithm is simple, and it is easy to promote on the existing low-cost pulsator washing machine main control board.

[0039] Furthermore, the motor power-off period in step S3 specifically refers to the time period after the microcontroller MCU shuts off power to the forward or reverse end of the motor; In step S3, the voltage detection is specifically performed by a microcontroller (MCU) analog-to-digital converter.

[0040] The detection in this invention includes using the analog-to-digital converter (ADC) of the MCU. The input of the ADC is obtained through a voltage divider network and a bias circuit. The bias circuit provides a DC bias voltage such that when the motor back EMF is zero, the voltage input to the ADC is half of the MCU's supply voltage. An operational amplifier superimposes the DC bias voltage onto the voltage output from the voltage divider network and outputs it to the ADC.

[0041] Furthermore, it also includes step S4, wiring of other loads, one end of other loads in the washing machine is connected to the common terminal of the motor, and the other end of other loads is electrically connected to the second pole of the single-phase AC power supply; the control terminal of other loads is connected to the signal control terminal of the microcontroller MCU.

[0042] The present invention utilizes the MCU to control the output of the first pole, so as to selectively connect the first pole to other loads, thereby realizing the control of the other loads.

[0043] A non-isolated back EMF detection system for a pulsator fixed-frequency washing machine motor is characterized by comprising a single-phase AC power supply, a motor, a microcontroller (MCU), a motor control unit, and a voltage detection unit. Both the forward and reverse ends of the motor are electrically connected to the second pole of the single-phase AC power supply and the signal control terminal of the microcontroller (MCU) through the motor control unit. The motor control unit is used to control the forward and reverse rotation of the motor. The common terminal of the motor and the VSS terminal of the microcontroller MCU are both electrically connected to the first pole of the single-phase AC power supply. The common terminal of the motor is connected to the signal detection terminal of the microcontroller MCU through a voltage detection unit. The voltage detection unit is used to detect the voltage of the forward or reverse terminal relative to VSS during the power-off period of the motor to obtain the back EMF signal.

[0044] The present invention relates to a microcontroller (MCU), which is powered by a single-phase AC power supply, with the output ground terminal of the single-phase AC power supply being VSS. A motor control unit, controlled by the MCU, is used to selectively connect the second pole to the forward or reverse rotation terminal to achieve forward or reverse rotation of the motor. A load control unit, controlled by the MCU, is used to selectively connect the first pole to other electrical components to control those other electrical components. A voltage detection unit is used to detect the voltage of the forward rotation terminal relative to VSS, or the voltage of the reverse rotation terminal relative to VSS, when the motor is powered off, to provide a back EMF detection signal to the MCU, thereby achieving non-isolated detection.

[0045] Furthermore, the common terminal of the motor is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply. The switching control terminals of other loads are connected to the signal control terminals of the microcontroller (MCU) through the load control unit.

[0046] This invention connects the motor's common terminal to one end of another load. When a load needs to be controlled, the MCU only needs to control the switch connected between the first pole and the load to turn on. Since the control switches of these loads are connected in series in the neutral circuit, and their control reference ground is the MCU's VSS, the MCU can directly drive these switches without the need for optocoupler isolation.

[0047] Furthermore, the first pole of the single-phase AC power supply is the neutral wire, and the second pole is the live wire; or, the first pole of the single-phase AC power supply is the live wire, and the second pole is the neutral wire.

[0048] This invention allows for the selection of either the live wire or the neutral wire to be connected to the common terminal based on actual conditions, facilitating the detection of the back EMF of the washing machine motor. It is simple, convenient, and beneficial for suction applications.

[0049] Furthermore, the VSS terminal of the microcontroller MCU is electrically connected to the first pole of a single-phase AC power supply through a resistor.

[0050] Resistors ensure the power supply safety of the microcontroller (MCU) and extend its lifespan.

[0051] Furthermore, the other loads include at least one of an inlet valve, a drain valve, a traction device, and a heater.

[0052] Other loads are other working components on the washing machine, such as the inlet valve, drain valve, actuator, and heater, which ensure the normal operation of the washing machine and the control of the microcontroller (MCU). Additionally, one end of the inlet valve, drain valve, and actuator is connected to the common terminal of the motor to ensure circuit simplicity, reduce operating costs, and ensure the safety of non-isolated back EMF detection.

[0053] Furthermore, the motor control unit includes a control switch and a signal control module. The forward and reverse ends of the motor are connected to the second pole of a single-phase AC power supply through different control switches. The control terminal of the control switch is electrically connected to the signal control terminal of the microcontroller (MCU) through the signal control module.

[0054] This invention uses a microcontroller (MCU) to control the on / off state of a control switch via a signal control module, thus ensuring the operation of the motor control unit and controlling the forward and reverse rotation of the motor to guarantee the normal use of the washing machine. Furthermore, the control switches in the motor control unit include thyristor TR1 and thyristor TR2; the signal control module includes optocoupler PH1 and optocoupler PH2. The forward rotation end of the motor is connected to the T2 end of the thyristor TR1, and the T1 end of the thyristor TR1 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR1 is connected in series with capacitor C1, resistor R1, and the T1 terminal of the thyristor TR1 in sequence. The control terminal G of the thyristor TR1 is connected to one end of resistor R2 and one end of resistor R10. The other end of resistor R10 is connected to the second pole of a single-phase AC power supply; A capacitor C6 is connected in parallel across the two ends of resistor R10; The other end of resistor R2 is connected to the collector of optocoupler PH1, and the emitter of optocoupler PH1 is grounded; The anode of optocoupler PH1 is connected to the DJ+ pin of the microcontroller MCU through a control circuit; The cathode of optocoupler PH1 is connected to the VSS pin of the microcontroller MCU; The reverse end of the motor is connected to the T2 terminal of the thyristor TR2, and the T1 terminal of the thyristor TR2 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR2 is connected in series with the capacitor C3, the resistor R4, and the T1 terminal of the thyristor TR2. The control terminal G of the thyristor TR2 is connected to one end of resistor R3 and one end of resistor R6. The other end of resistor R3 is connected to the second pole of a single-phase AC power supply; A capacitor C2 is connected in parallel across the two ends of resistor R3; The other end of resistor R6 is connected to the collector of optocoupler PH2, and the emitter of optocoupler PH2 is grounded; The anode of optocoupler PH2 is connected to the DJ pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH2 is connected to the VSS pin of the microcontroller MCU; An inductor and a capacitor C5 are connected in parallel between the forward and reverse ends of the motor.

[0055] This invention's MCU issues the following command: The MCU's DJ+ pin outputs a high level. Optocoupler conduction: Current flows through the LED of optocoupler PH1, turning on the phototransistor on the secondary side of PH1. Triggering TRIAC: Current flows from the live wire L—resistor R10—gate of TRIAC TR1—resistor R2—collector of optocoupler PH1—emitter of optocoupler PH1—ground. This current triggers TR1 to conduct. Motor start: After TR1 conducts, the live wire L is directly connected to the motor's forward rotation terminal W, and the motor begins to rotate forward. Turn-off: The MCU's DJ+ pin outputs a low level, the optocoupler turns off, and the control electrode current of TR1 disappears. When the AC current crosses zero, TR1 naturally turns off, and the motor is powered off.

[0056] Furthermore, the voltage detection unit includes a voltage divider resistor network and a bias circuit; the bias circuit includes an operational amplifier, the common terminal and the reverse terminal of the motor are connected to the voltage divider resistor network, the sampling point of the voltage divider resistor network is connected to the input terminal of the operational amplifier in the bias circuit, and the output terminal of the operational amplifier is connected to the analog-to-digital converter pin in the microcontroller MCU.

[0057] The bias circuit is configured to provide a DC bias voltage such that when the motor back EMF is zero, the voltage input to the MCU analog-to-digital converter is half of the MCU supply voltage; the bias circuit includes an operational amplifier, the middle node of a voltage divider network is connected to the input of the operational amplifier, and the output of the operational amplifier is connected to the MCU's analog-to-digital converter pin; the operational amplifier is also connected to a bias voltage source to apply the DC bias voltage.

[0058] Furthermore, the voltage detection unit includes a voltage divider resistor network comprising resistors R8, R5, Rn, and R7, with the two ends of resistor R7 serving as sampling points for the voltage divider resistor network; the bias circuit includes an operational amplifier, resistors R11, R12, and R13, and capacitor C4, all housed within the microcontroller MCU. The reverse end of the motor is connected in series with resistors R8, R5, Rn, R7, and the common end of the motor. The common end of the motor is connected to the VSS pin of the microcontroller MCU. The connection point between resistor R7 and the common terminal of the motor is connected to one end of resistor R11. The other end of resistor R11 is simultaneously connected to one end of resistor R12 and the positive input terminal P+ pin of the operational amplifier in the microcontroller MCU. The other end of resistor R12 is connected to the VDD pin of the microcontroller MCU. A capacitor C4 is connected in parallel across resistor R11; The connection point between resistors Rn and R7 is connected to one end of resistor R13, and the other end of resistor R13 is connected to the negative input P-pin of the operational amplifier in the microcontroller MCU.

[0059] The back electromotive force is generated in the working process of this invention: when the motor is de-energized and coasting, a back electromotive force E_RC is generated between the reverse end and the common end.

[0060] Signal attenuation: E_RC is attenuated by the R8-R5-Rn-R7 voltage divider network, resulting in a small signal voltage at node B: V_B=E_RC×[R7 / (R8+R5+Rn+R7)]; Bias superposition: Add the attenuated V_B to the DC bias (approximately 1 / 2 VDD) to obtain: V_ADC = 1 / 2VDD + (V_B × Gain) ADC sampling: The MCU's ADC acquires V_ADC and converts it into a digital quantity.

[0061] Digital processing: Subtract the digital value corresponding to 1 / 2VDD to restore the pure back EMF waveform; calculate the frequency—motor speed—load weighing; analyze amplitude fluctuations—eccentricity detection; detect amplitude abnormalities—overvoltage protection.

[0062] Furthermore, the load control unit includes a silicon controlled rectifier (SCR) TR3; One end of the thyristor TR3 is connected to the common terminal of the motor, and the other end of the thyristor TR3 is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply; the control terminal of the thyristor TR3 is connected to the CTR-TR3 pin of the microcontroller MCU through a control circuit.

[0063] TR3 is a neutral-side switch connected between "other loads" and "neutral line, i.e. MCU ground", enabling the MCU to directly and non-isolatedly control high-voltage loads such as inlet valves, drain valves, and traction devices, thereby eliminating optocoupler isolation devices and achieving the extremely low cost goal of this invention.

[0064] Furthermore, the load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 and thyristor TRn is connected to the common terminal of the motor, and the other end of the thyristor TR4 and thyristor TRn is connected to one end of different other loads respectively. The other end of the different other loads is connected to the second pole of the single-phase AC power supply. The control terminals of the thyristor TR4 and thyristor TRn are connected to the CTR-TR4 pin and CTR-TRn pin of the microcontroller MCU respectively through the control circuit. In the thyristor TRn, n is an integer greater than 4.

[0065] Different connection methods can be used for different loads according to the actual situation to ensure power supply to the load and control of it. TR4 and TRn are extension circuits with the same structure as TR3. They are used for non-isolated control of multiple other high-voltage loads in the washing machine, such as drain valve, actuator, and heating element, in addition to the motor. By reusing the same circuit mode, optocoupler-free control of all high-voltage loads can be achieved, achieving the goals of lowest cost, simplest design, and easiest expansion.

[0066] Furthermore, the load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TR4 is connected to one end of another load, which in turn is connected to the common terminal of the motor. The control terminal of the thyristor TR4 is connected to the collector of the optocoupler PH4 through resistor R15, and the emitter of the optocoupler PH4 is grounded. A resistor R18 is connected in parallel directly between the control terminal of the thyristor TR4 and the second pole of the single-phase AC power supply, and a capacitor C9 is connected in parallel across the two ends of the resistor R15. The anode of optocoupler PH4 is connected to the CTR-TR4 pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH4 is connected to the VSS pin of the microcontroller MCU; One end of the thyristor TRn is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TRn is connected to one end of another load, and the other end of the other load is connected to the common terminal of the motor. The control terminal of the thyristor TRn is connected to the collector of the optocoupler PHn through resistor R9, and the emitter of the optocoupler PHn is grounded; A resistor R17 is directly connected in parallel with the control terminal of the thyristor TRn and the second pole of the single-phase AC power supply. A capacitor C8 is connected in parallel across the two ends of the resistor R17. The anode of the optocoupler PHn is connected to the CTR-TRn pin of the microcontroller MCU via a control circuit; The cathode of the optocoupler PHn is connected to the VSS pin of the microcontroller MCU; where n in the thyristor TRn is an integer greater than 4.

[0067] Similar to TR3, TR4-TRn are neutral-side switches connected between "other loads" and "neutral", enabling the MCU to directly and non-isolatedly control high-voltage loads such as inlet valves, drain valves, and traction devices, thereby eliminating optocoupler isolation devices and achieving the extremely low cost goal of this invention.

[0068] Specifically, in Embodiment 1 of the present invention as follows Figure 2 As shown: The common terminal is connected to the neutral wire, and the forward / reverse control wire is connected to the live wire. Back EMF detection power is drawn between the reverse terminal and the common terminal. The forward / reverse thyristors TR1 and TR2 are floated to the positive AVDD power supply, and TR1 and TR2 are also connected to the live wire, controlling its on / off state. One end of each of the other high-voltage loads (excluding the motor) is connected to thyristors TR3, TR4, and TRn, and after being controlled by TR3, TR4, and TRn, it is connected to the neutral wire of the common terminal. TR3, TR4, and TRn are floated to VSS ground, meaning the neutral wire of the common terminal is floated to VSS ground. The other end of each high-voltage load (excluding the motor) is connected to the live wire. AVDD positive power supply and AVSS ground, and VDD positive power supply and VSS ground are two isolated power supplies used to separately control the motor and other high-voltage loads. A voltage divider resistor, such as R8, and a sampling resistor, such as R7, are connected between the reverse end and the common end of the motor. The voltage waveform of the sampling resistor R7 is collected by the operational amplifier circuit and input to the MCU port for the MCU to perform reverse electromotive force data acquisition and processing, so as to achieve the purpose of detecting the back electromotive force of the motor. The U3 operational amplifier can be built into the MCU chip or external.

[0069] Embodiment 2 of the present invention Figure 3 As shown: the common terminal is connected to the neutral wire, and the forward / reverse control wire is connected to the fire control wire. The back EMF detection draws power between the reverse terminal and the common terminal. The circuit connection is basically the same as in Embodiment 1 of this invention, except that the forward / reverse thyristors TR1 and TR2 are floated to AVSS ground.

[0070] Embodiment 3 of the present invention Figure 4As shown: the common terminal is connected to the neutral wire, and the forward and reverse control wires are connected to the fire control wire. The back EMF detection power is drawn between the reverse terminal and the common terminal. The circuit connection is basically the same as in Embodiment 1 of this invention, except that the neutral wire of the common terminal is floated to the VDD power supply, and the operational amplifier sampling circuit is slightly different.

[0071] Embodiment 4 of the present invention Figure 5 As shown: the common terminal is connected to the neutral wire, and the forward / reverse control wire is connected to the fire control wire. The back EMF detection draws power between the reverse terminal and the common terminal. The circuit connection is basically the same as in Example 3, except that the forward / reverse thyristors TR1 and TR2 are floated to AVSS ground.

[0072] Embodiment 5 of the present invention Figure 6 As shown: The common terminal is connected to the live wire, and the forward / reverse control is connected to the neutral wire. Back EMF detection draws power between the reverse terminal and the common terminal. The forward / reverse thyristors TR1 and TR2 are floated to the positive AVDD power supply, and TR1 and TR2 are also connected to the neutral wire, controlling its on / off state. One end of each high-voltage load (excluding the motor) is connected to thyristors TR3, TR4, and TRn, and after being controlled by TR3, TR4, and TRn, it is connected to the live wire of the common terminal. TR3, TR4, and TRn are floated to VSS ground, meaning the live wire of the common terminal is floated to VSS ground. The other end of each high-voltage load (excluding the motor) is connected to the neutral wire. AVDD positive power supply and AVSS ground, and VDD positive power supply and VSS ground are two isolated power supplies used to separately control the motor and other high-voltage loads. A voltage divider resistor (such as R8) and a sampling resistor (such as R7) are connected between the reverse end and the common end of the motor. The voltage waveform of the sampling resistor R7 is collected by the operational amplifier circuit and input to the MCU port for the MCU to perform reverse electromotive force data acquisition and processing, so as to achieve the purpose of detecting the back electromotive force of the motor. The U3 operational amplifier can be built into the MCU chip or external.

[0073] Embodiment Six of the present invention Figure 7 As shown: the common terminal is connected to the live wire, and the forward / reverse control is connected to the neutral wire. The back EMF detection draws power between the reverse terminal and the common terminal. It is basically the same as in Example 5, except that the forward / reverse thyristors TR1 and TR2 are floated to AVSS ground.

[0074] Embodiment 7 of the present invention Figure 8 As shown: the common terminal is connected to the live wire, and the forward / reverse control is the neutral wire. The back EMF detection power is drawn between the reverse terminal and the common terminal. It is basically the same as Embodiment 5, except that the common terminal live wire is floated to the VDD power supply, and the operational amplifier sampling circuit is slightly different.

[0075] Embodiment 8 of the present invention Figure 9 As shown: the common terminal is connected to the live wire, and the forward / reverse control is connected to the neutral wire. The back EMF detection draws power between the reverse terminal and the common terminal. It is basically the same as in Embodiment 7, except that the forward / reverse thyristors TR1 and TR2 are floated to AVSS ground.

[0076] Embodiment Nine of the present invention Figure 10As shown: the common terminal is connected to the neutral wire, and the forward / reverse control wire is connected to the ignition wire. The back EMF detection draws power between the forward terminal and the common terminal. This is basically the same as Example 1, except that the back EMF detection draws power between the forward terminal and the common terminal; everything else is the same. The various scenarios for drawing power between the forward terminal and the common terminal are the same as before and will not be repeated.

[0077] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A non-isolated method for detecting the back electromotive force of a pulsator-driven fixed-frequency washing machine motor, wherein the power supply terminal of the washing machine is connected to a single-phase AC power supply, the connection terminal of the single-phase AC power supply includes a first pole and a second pole, and the washing machine motor has a common terminal, a forward rotation terminal, and a reverse rotation terminal; characterized in that, The method and steps are as follows: Step S1: Wiring the motor. The common terminal of the motor is connected to the first pole of the single-phase AC power supply, and the forward and reverse terminals of the motor are connected to the second pole of the single-phase AC power supply. The forward and reverse terminals of the motor are connected to the signal control terminal of the microcontroller (MCU) through the motor control unit. Step S2: Wiring the microcontroller MCU. Connect the power ground VSS of the internal microcontroller MCU of the washing machine to the first pole of the single-phase AC power supply. Step S3: Back EMF detection. During the motor power-off period, the back EMF signal is obtained by detecting the voltage between the motor common terminal and the forward rotation terminal, or the voltage between the motor common terminal and the reverse rotation terminal, through the microcontroller (MCU).

2. The non-isolated detection method for back EMF of a pulsator-driven fixed-frequency washing machine motor according to claim 1, characterized in that, The motor power-off period in step S3 is specifically the time period after the microcontroller MCU shuts off the power supply to the forward or reverse end of the motor. In step S3, the voltage detection is specifically performed by the analog-to-digital converter of the microcontroller MCU.

3. The non-isolated detection method for back EMF of a pulsator-driven fixed-frequency washing machine motor according to claim 1, characterized in that, It also includes step S4, wiring of other loads, one end of other loads in the washing machine is connected to the common terminal of the motor, and the other end of other loads is electrically connected to the second pole of the single-phase AC power supply; the control terminal of other loads is connected to the signal control terminal of the microcontroller MCU.

4. A non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor, characterized in that, Includes a single-phase AC power supply, a motor, a microcontroller (MCU), a motor control unit, and a voltage detection unit; Both the forward and reverse ends of the motor are electrically connected to the second pole of the single-phase AC power supply and the signal control terminal of the microcontroller (MCU) through the motor control unit. The motor control unit is used to control the forward and reverse rotation of the motor. The common terminal of the motor and the VSS terminal of the microcontroller MCU are both electrically connected to the first pole of the single-phase AC power supply. The common terminal of the motor is connected to the signal detection terminal of the microcontroller MCU through a voltage detection unit. The voltage detection unit is used to detect the voltage of the forward or reverse terminal relative to VSS during the power-off period of the motor to obtain the back EMF signal.

5. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 4, characterized in that, The common terminal of the motor is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply. The switching control terminals of other loads are connected to the signal control terminals of the microcontroller (MCU) through the load control unit.

6. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 5, characterized in that, The first pole of the single-phase AC power supply is the neutral wire, and the second pole is the live wire; or, the first pole of the single-phase AC power supply is the live wire, and the second pole is the neutral wire.

7. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 6, characterized in that, The VSS terminal of the microcontroller (MCU) is electrically connected to the first pole of a single-phase AC power supply via a resistor.

8. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 7, characterized in that, The other loads include at least one of the following: inlet valve, drain valve, actuator, and heater.

9. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 4, characterized in that, The motor control unit includes a control switch and a signal control module. The forward and reverse ends of the motor are connected to the second pole of a single-phase AC power supply through different control switches. The control terminal of the control switch is electrically connected to the signal control terminal of the microcontroller (MCU) through the signal control module.

10. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 9, characterized in that, The control switches in the motor control unit include thyristors TR1 and TR2; the signal control module includes optocouplers PH1 and PH2. The forward rotation end of the motor is connected to the T2 end of the thyristor TR1, and the T1 end of the thyristor TR1 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR1 is connected in series with capacitor C1, resistor R1, and the T1 terminal of the thyristor TR1 in sequence. The control terminal G of the thyristor TR1 is connected to one end of resistor R2 and one end of resistor R10. The other end of resistor R10 is connected to the second pole of a single-phase AC power supply; A capacitor C6 is connected in parallel across the two ends of resistor R10; The other end of resistor R2 is connected to the collector of optocoupler PH1, and the emitter of optocoupler PH1 is grounded; The anode of optocoupler PH1 is connected to the DJ+ pin of the microcontroller MCU through a control circuit; The cathode of optocoupler PH1 is connected to the VSS pin of the microcontroller MCU; The reverse end of the motor is connected to the T2 terminal of the thyristor TR2, and the T1 terminal of the thyristor TR2 is connected to the second pole of the single-phase AC power supply. The T2 terminal of the thyristor TR2 is connected in series with the capacitor C3, the resistor R4, and the T1 terminal of the thyristor TR2. The control terminal G of the thyristor TR2 is connected to one end of resistor R3 and one end of resistor R6. The other end of resistor R3 is connected to the second pole of a single-phase AC power supply; A capacitor C2 is connected in parallel across the two ends of resistor R3; The other end of resistor R6 is connected to the collector of optocoupler PH2, and the emitter of optocoupler PH2 is grounded; The anode of optocoupler PH2 is connected to the DJ pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH2 is connected to the VSS pin of the microcontroller MCU; An inductor and a capacitor C5 are connected in parallel between the forward and reverse ends of the motor.

11. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 4, characterized in that, The voltage detection unit includes a voltage divider resistor network and a bias circuit; the bias circuit includes an operational amplifier, the common terminal and the reverse terminal of the motor are connected to the voltage divider resistor network, the sampling point of the voltage divider resistor network is connected to the input terminal of the operational amplifier in the bias circuit, and the output terminal of the operational amplifier is connected to the analog-to-digital converter pin in the microcontroller MCU.

12. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 11, characterized in that, The voltage detection unit includes a voltage divider resistor network consisting of resistors R8, R5, Rn, and R7, with the two ends of resistor R7 serving as sampling points for the voltage divider resistor network. The bias circuit includes an operational amplifier, resistors R11, R12, and R13, and a capacitor C4, all located within the microcontroller MCU. The reverse end of the motor is connected in series with resistors R8, R5, Rn, R7, and the common end of the motor. The common end of the motor is connected to the VSS pin of the microcontroller MCU. The connection point between resistor R7 and the common terminal of the motor is connected to one end of resistor R11. The other end of resistor R11 is simultaneously connected to one end of resistor R12 and the positive input terminal P+ pin of the operational amplifier in the microcontroller MCU. The other end of resistor R12 is connected to the VDD pin of the microcontroller MCU. A capacitor C4 is connected in parallel across resistor R11; The connection point between resistors Rn and R7 is connected to one end of resistor R13, and the other end of resistor R13 is connected to the negative input P-pin of the operational amplifier in the microcontroller MCU.

13. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 4, characterized in that, The load control unit includes a thyristor TR3; One end of the thyristor TR3 is connected to the common terminal of the motor, and the other end of the thyristor TR3 is connected to one end of another load, and the other end of the other load is connected to the second pole of a single-phase AC power supply; the control terminal of the thyristor TR3 is connected to the CTR-TR3 pin of the microcontroller MCU through a control circuit.

14. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 13, characterized in that, The load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 and thyristor TRn is connected to the common terminal of the motor, and the other end of the thyristor TR4 and thyristor TRn is connected to one end of different other loads respectively. The other end of the different other loads is connected to the second pole of the single-phase AC power supply. The control terminals of the thyristor TR4 and thyristor TRn are connected to the CTR-TR4 pin and CTR-TRn pin of the microcontroller MCU respectively through the control circuit. In the thyristor TRn, n is an integer greater than 4.

15. The non-isolated back EMF detection system for a pulsator-driven fixed-frequency washing machine motor according to claim 13, characterized in that, The load control unit also includes a silicon controlled rectifier (SCR) TR4 and a silicon controlled rectifier (SCR) TRn; One end of the thyristor TR4 is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TR4 is connected to one end of another load, which in turn is connected to the common terminal of the motor. The control terminal of the thyristor TR4 is connected to the collector of the optocoupler PH4 through resistor R15, and the emitter of the optocoupler PH4 is grounded. A resistor R18 is connected in parallel directly between the control terminal of the thyristor TR4 and the second pole of the single-phase AC power supply, and a capacitor C9 is connected in parallel across the two ends of the resistor R15. The anode of optocoupler PH4 is connected to the CTR-TR4 pin of the microcontroller MCU via a control circuit; The cathode of optocoupler PH4 is connected to the VSS pin of the microcontroller MCU; One end of the thyristor TRn is connected to the second pole of a single-phase AC power supply, and the other end of the thyristor TRn is connected to one end of another load, and the other end of the other load is connected to the common terminal of the motor. The control terminal of the thyristor TRn is connected to the collector of the optocoupler PHn through resistor R9, and the emitter of the optocoupler PHn is grounded; A resistor R17 is directly connected in parallel with the control terminal of the thyristor TRn and the second pole of the single-phase AC power supply. A capacitor C8 is connected in parallel across the two ends of the resistor R17. The anode of the optocoupler PHn is connected to the CTR-TRn pin of the microcontroller MCU via a control circuit; The cathode of the optocoupler PHn is connected to the VSS pin of the microcontroller MCU; where n in the thyristor TRn is an integer greater than 4.

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