Single-phase asynchronous motor starting control circuit based on MCU and dual thyristor

Abstract

The present application relates to the technical field of single-phase asynchronous motors, and discloses a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors, which includes an MCU control unit, a main thyristor, a secondary thyristor, an electricity metering chip, and a protection circuit. In particular, during the startup phase, the MCU control unit first sends a trigger signal to the secondary thyristor to put the secondary thyristor in a conductive state, and the secondary thyristor connects to the starting winding to provide additional starting torque for the single-phase asynchronous motor; after the startup conditions are met, the MCU control unit then sends a trigger signal to the main thyristor to put the main thyristor in a conductive state, and the main thyristor connects to the live wire to put the single-phase asynchronous motor into normal operation. In this way, the starting winding is energized only when necessary, avoiding energy loss caused by continuous heating of the PTC and improving the overall energy efficiency of the system.

Description

Technical Field

[0001] The present application relates to the technical field of single-phase asynchronous motors, and more specifically, to a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors. Background Art

[0002] Single-phase asynchronous motors are widely used in modern household appliances and industrial equipment due to their simple structure and high cost-effectiveness. However, these motors do not have the ability to start themselves and usually require an additional starting device to provide the necessary starting current to enable them to reach normal operating speed. Traditionally, this is achieved by using mechanical starters such as hammer starters or PTC starters. Although these methods have proven effective in the past, they have some inherent limitations. For example, hammer starters rely on the suction force generated by the electromagnetic coil to control the opening and closing of contacts. This mechanism has a slow response speed, is prone to wear, and may cause starting failure under extreme operating conditions. On the other hand, although PTC starters have a certain degree of automatic recovery capability, they are limited by thermal inertia, have a slow response speed, and long-term operation can lead to energy waste and performance degradation.

[0003] With technological advancements, particularly the development of microcontroller units (MCUs) and power electronics, the demand for more intelligent, efficient, and reliable starting solutions has become increasingly urgent. To address this issue, this application proposes a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors. This solution leverages the powerful processing capabilities of the MCU and the fast response of the thyristors to achieve precise control of the motor starting process. Summary of the Invention

[0004] In order to solve the above technical problems, the present application is proposed. An embodiment of the present application proposes a single-phase asynchronous motor starting control circuit based on MCU and dual thyristors, which includes an MCU control unit, a main thyristor, a sub-thyristor, an electricity metering chip and a protection circuit. In particular, in the starting stage, the MCU control unit first sends a trigger signal to the sub-thyristor to put the sub-thyristor in a conducting state, and the sub-thyristor connects the starting winding to provide additional starting torque for the single-phase asynchronous motor; after the starting conditions are met, the MCU control unit again sends a trigger signal to the main thyristor to put the main thyristor in a conducting state, and the main thyristor connects the live wire to allow the single-phase asynchronous motor to enter a normal operating state. In this way, the starting winding is energized only when necessary, avoiding energy loss caused by continuous heating of the PTC and improving the overall energy efficiency of the system.

[0005] Another technical advantage of the single-phase asynchronous motor starting control circuit based on MCU and dual thyristors provided in this application is that the main thyristor plus the auxiliary thyristor solution is used to replace the PTC, thereby achieving precise control of the on and off of the starting winding and avoiding the problem of starting failure caused by PTC aging or ambient temperature changes.

[0006] Another technical advantage of the single-phase asynchronous motor starting control circuit based on MCU and dual thyristors provided by the present application is that compared with the thermal inertia control of PTC, the present invention uses MCU to control the on and off of thyristors in real time, achieving millisecond-level response and improving starting accuracy.

[0007] According to one aspect of the present application, a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors is provided, comprising: an MCU control unit, a main thyristor, a secondary thyristor, an electricity metering chip, and a protection circuit; the main thyristor is electrically connected to the MCU control unit for controlling the on / off of the live wire; the secondary thyristor is electrically connected to the MCU control unit for controlling the on / off of the starting winding; the electricity metering chip is electrically connected to the MCU control unit for monitoring circuit parameters; and the protection circuit is connected to the MCU control unit for providing circuit protection.

[0008] In one possible implementation, during the startup phase, the MCU control unit first sends a trigger signal to the auxiliary thyristor to put the auxiliary thyristor in the on state, and the auxiliary thyristor connects the starting winding to provide additional starting torque for the single-phase asynchronous motor; after the startup conditions are met, the MCU control unit then sends a trigger signal to the main thyristor to put the main thyristor in the on state, and the main thyristor connects the live wire to enable the single-phase asynchronous motor to enter a normal operating state.

[0009] In a possible implementation, the start condition is a fixed delay.

[0010] In a possible implementation, the starting condition is that the AC power supply voltage crosses a zero point.

[0011] In one possible implementation, after a startup condition is met, the MCU control unit sends a trigger signal to the main thyristor to put the main thyristor into a conducting state, including: collecting motor current and motor voltage through the electricity metering chip to obtain a time series of the motor current; calculating a current rise / fall rate value based on the time series of the motor current; determining a load type based on a comparison between the current rise / fall rate value and a preset threshold, the load type including light load, medium load, and heavy load; and setting an initial trigger angle of the main thyristor by the MCU control unit based on the load type.

[0012] In one possible implementation, when the load type is light load, the initial trigger angle of the main thyristor is 80°; when the load type is medium load, the initial trigger angle of the main thyristor is 110°; when the load type is heavy load, the initial trigger angle of the main thyristor is 130°.

[0013] In one possible implementation, during the operation phase, the MCU control unit determines whether the single-phase asynchronous motor has reached a stable operating state through circuit parameters collected by the electricity metering chip. After determining that the single-phase asynchronous motor has reached a stable operating state, the MCU control unit sends a signal to turn off the auxiliary thyristor to disconnect the starting winding, and the main thyristor remains turned on.

[0014] In one possible implementation, during the operation phase, the MCU control unit receives circuit parameters collected by the electricity metering chip, and determines whether there is an abnormality based on the circuit parameters collected by the electricity metering chip; after receiving the abnormal signal, the MCU control unit disconnects the main thyristor.

[0015] Compared to existing technologies, the single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors (SCRs) provided in this application integrates an advanced MCU control unit, primary and secondary SCRs, and an energy metering chip, providing a more intelligent and efficient single-phase asynchronous motor starting solution. The dual-path control strategy of the primary and secondary SCRs is designed to precisely manage the motor starting process: the primary SCR controls the live wire, ensuring safe operation of the entire circuit; the secondary SCR specifically controls the connection and disconnection of the starter winding, achieving precise control of the starting time, thus completely replacing the functions of a traditional PTC starter. Furthermore, the introduction of the energy metering chip enables the system to monitor key parameters such as current, voltage, and power in real time, and provides multiple protection mechanisms such as overcurrent, overvoltage, and overtemperature, significantly improving system safety and stability. Leveraging the powerful processing power of the MCU, the adaptive starting algorithm dynamically adjusts the starting current, starting time, and firing angle according to different load conditions, ensuring a smooth and energy-efficient motor starting process under various operating conditions. Furthermore, this solution supports remote configuration and optimization via the MCU, making it suitable for modern smart home appliances and IoT devices, providing users with greater flexibility and convenience. In this way, the problems of slow response speed, high energy consumption and poor reliability in the existing technology are solved, and the motor starting process is highly controllable and adaptable, thereby improving the starting reliability, protection capability and response speed, and realizing the upgrade of single-phase asynchronous motor starting technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other purposes, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0017] Figure 1 The figure illustrates a schematic principle block diagram of a single-phase asynchronous motor starting control circuit based on MCU and dual thyristors according to an embodiment of the present application.

[0018] Figure 2 The figure illustrates a schematic flow chart of starting control in a single-phase asynchronous motor starting control circuit based on MCU and dual thyristors according to an embodiment of the present application.

[0019] Figure 3 The figure illustrates a schematic flow chart of S2 in a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] Below, the exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the exemplary embodiments described herein.

[0021] In order to solve the problems of slow response, high energy consumption and poor reliability in the existing technology, Figure 1 As shown, the present application provides a single-phase asynchronous motor starting control circuit based on MCU and dual thyristors, as shown in FIG. Figure 1 As shown, a single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors includes: an MCU control unit, a main thyristor, a secondary thyristor, an electricity metering chip, and a protection circuit; the main thyristor is electrically connected to the MCU control unit for controlling the on / off of the live wire; the secondary thyristor is electrically connected to the MCU control unit for controlling the on / off of the starting winding; the electricity metering chip is electrically connected to the MCU control unit for monitoring circuit parameters; and the protection circuit is connected to the MCU control unit for providing circuit protection.

[0022] In one embodiment, the MCU control unit serves as the control core, processing various input signals and generating corresponding control signals based on preset logic to drive the main and auxiliary thyristors. Its output port is directly connected to the gates of the main and auxiliary thyristors. It provides trigger signals through driver circuits such as optocoupler isolation drivers or gate driver ICs to control the on / off switching of the two thyristors. This ensures that the MCU can quickly respond and adjust the motor startup process based on real-time monitoring data. Simultaneously, the MCU's input port is connected to the data output interface of the power metering chip, receiving key parameter information such as current, voltage, and power from the chip. The MCU also receives alarm signals such as overcurrent, overvoltage, and overtemperature from the protection circuit and may obtain additional sensor data through signal detection circuitry to provide a more comprehensive understanding of the motor's operating status. The MCU itself requires a stable low-voltage DC power supply (such as 5V or 3.3V) to ensure normal operation, which can be provided by a separate power module.

[0023] The main thyristor (SCR) is connected in series between the live (L) line of the AC power supply and the motor's common terminal or main winding input terminal, controlling the on / off of the entire motor power supply circuit. Its gate and cathode are connected to control signals provided by the MCU (via a driver circuit), allowing the MCU to flexibly control the motor's operating status based on actual needs. The slave thyristor (SCR) controls the on / off connection of the motor's start winding. It is connected in series with the motor's start winding circuit, extending from the motor's common terminal, passing through the start winding, and then through the slave thyristor back to the neutral (N) line of the AC power supply or joining the main winding circuit. This precise control of the slave thyristor by the MCU enables effective management of the motor's startup process.

[0024] The energy metering chip monitors motor parameters such as motor speed, voltage, and power in real time and feeds this data back to the MCU. This data is used not only to optimize startup control but also to implement protection functions such as overcurrent and overvoltage. Therefore, it requires access to voltage and current sampling signals, obtained through a resistor divider network and a current transformer or sampling resistor, respectively. These sampling signals provide the MCU with detailed information about the circuit status, enabling dynamic adjustments. The data output interface of the energy metering chip is connected to the corresponding input interface of the MCU to facilitate data transmission.

[0025] The protection circuit is used to promptly cut off the power supply when an abnormality is detected to prevent damage to the motor. It can independently detect parameters such as current, voltage, and temperature, and send fault / alarm signals to the MCU. Those skilled in the art will understand that in some cases, the protection circuit can also directly act on the drive signal of the thyristor, or even control the relay to cut off the main power supply, providing hardware-level redundant protection. In the embodiments of the present application, all abnormal conditions are reported to the MCU, and the MCU performs the corresponding shutdown operation.

[0026] In one embodiment, Figure 2 As shown, the starting control process of the single-phase asynchronous motor starting control circuit based on MCU and dual thyristors includes: S1, in the starting stage, the MCU control unit first sends a trigger signal to the auxiliary thyristor to put the auxiliary thyristor in the on state, and the auxiliary thyristor connects the starting winding to provide additional starting torque for the single-phase asynchronous motor; S2, after the starting conditions are met, the MCU control unit again sends a trigger signal to the main thyristor to put the main thyristor in the on state, and the main thyristor connects the live wire to put the single-phase asynchronous motor into normal operation.

[0027] Specifically, at the beginning of the startup phase, the MCU first sends a trigger signal to the slave thyristor, turning it on. This connects the motor's starting winding, providing additional starting torque. This strategy is particularly important for single-phase asynchronous motors, which lack self-starting capabilities. The auxiliary magnetic field provided by the starting winding allows the motor to quickly overcome resistance at standstill and achieve rapid acceleration. This approach also effectively reduces the impact of starting current on the power grid, avoiding potential voltage drops or other electrical problems. Precisely controlling the conduction time of the slave thyristor during the initial startup phase ensures a smooth transition to stable operation. Once the motor meets the preset starting conditions, the MCU sends another trigger signal, this time to the master thyristor. The master thyristor then conducts, connecting the live wire and activating the motor's normal operation mode.

[0028] In one embodiment, the starting condition is a fixed delay, that is, after the auxiliary thyristor is connected to the starting winding, the MCU will wait for a preset time period, which is usually pre-set according to the specific parameters of the motor and its load conditions. In an embodiment of the present application, it can be set according to experience, for example, the auxiliary thyristor is set to automatically turn off 5 seconds after being triggered. During this period, the motor gradually accelerates to a certain speed through the additional torque provided by the starting winding. The advantage of this method is that it is relatively simple to implement and does not require complex sensors or algorithms to detect changes in the state of the motor. Once the set delay time is reached, the MCU will send a signal to the main thyristor to turn it on, thereby completing the transition from the startup phase to normal operation.

[0029] In one embodiment, the startup condition is when the AC power supply voltage crosses zero. That is, the MCU monitors the AC power supply voltage and triggers the main thyristor to turn on when it approaches zero (i.e., the voltage waveform crosses the zero axis). The reason for choosing to switch at this moment is that the current is at its lowest at this time, and the impact on the power grid and other electrical equipment is also minimal. Specifically, when the voltage is close to zero, the energy stored in the inductor element in the circuit is also at its lowest level, which means that switching the main thyristor at this moment can avoid generating large transient current shocks and protect the motor and other electrical components from damage. In addition, since the single-phase asynchronous motor needs to overcome a large static friction force in the early stage of startup, and the resistance gradually decreases as the speed increases, choosing to turn on the main thyristor at a time near the voltage zero crossing can make the motor transition to normal operation more smoothly.

[0030] In one embodiment, Figure 3 As shown, after the start-up conditions are met, the MCU control unit sends a trigger signal to the main thyristor to put the main thyristor into a conducting state, including: S21, collecting the motor current and motor voltage through the electricity metering chip to obtain a time series of the motor current; S22, calculating the current rise / fall rate value based on the time series of the motor current; S23, judging the load type based on the comparison between the current rise / fall rate value and a preset threshold, the load type including light load, medium load and heavy load; S24, based on the load type, the MCU control unit sets the initial trigger angle of the main thyristor.

[0031] Once the starting conditions are met, the MCU control unit sends a trigger signal to the main thyristor (SCR) through a precise series of steps to ensure the motor enters normal operation smoothly and efficiently. This process not only involves real-time monitoring of the motor current and voltage but also uses this data to determine the load type and set the main thyristor's initial trigger angle accordingly. Specifically, after the starting conditions are met, the MCU first uses the power metering chip to collect motor current and voltage data, obtaining a time series of the motor current. This time series is analyzed to calculate the current rise and fall rates, which are then compared with preset thresholds to determine the current motor load type (light, medium, or heavy). Based on the determined load type, the MCU control unit then sets the main thyristor's initial trigger angle accordingly to optimize the motor startup process.

[0032] Specifically, during the startup phase, when the secondary thyristor connects to the starter winding and the motor begins to accelerate, the MCU continuously monitors the motor's current and voltage parameters. This data is provided by the power metering chip, which accurately measures key circuit information such as current and voltage. By analyzing the time series of the motor current, the MCU can calculate the current rise or fall rate. For example, under light load conditions, the current rise rate is relatively slow during the initial startup phase because the motor faces less resistance. However, under heavy load conditions, the current rise rate increases significantly because the motor requires greater torque to overcome the greater resistance. Based on these rate values, the MCU compares them with preset thresholds to determine the current load condition. If the current rise rate is below a set value, the load is considered light; if it is in the middle range, the load is medium; and if it exceeds the upper limit, the load is considered heavy. In one specific embodiment, the thresholds can be set as follows: if the current rise rate is less than 5 amperes per second, the load is light; if it is between 5 and 10 amperes per second, the load is medium; and if it is greater than 10 amperes per second, the load is heavy. Of course, the above are only examples. These thresholds can be adjusted according to specific application scenarios and motor characteristics and do not constitute specific limitations.

[0033] Then, based on the determined load type, the MCU control unit further adjusts the initial trigger angle of the main thyristor. For light load conditions, a smaller trigger angle can be selected, which means that the thyristor will be turned on earlier in each AC cycle, allowing more current to flow into the motor without causing excessive impact. For medium and heavy load conditions, a larger trigger angle needs to be selected to ensure sufficient starting torque while avoiding damage to the equipment due to excessive current. This adaptive adjustment mechanism enables the system to respond flexibly to different working conditions, ensuring that the motor can achieve optimal starting effect under any load conditions. In a specific embodiment, when the load type is light load, the initial trigger angle of the main thyristor is 80°; when the load type is medium load, the initial trigger angle of the main thyristor is 110°; when the load type is heavy load, the initial trigger angle of the main thyristor is 130°.

[0034] In one embodiment, during the operation phase, the MCU control unit determines whether the single-phase asynchronous motor has reached a stable operating state through circuit parameters collected by the electricity metering chip. After determining that the single-phase asynchronous motor has reached a stable operating state, the MCU control unit sends a signal to turn off the auxiliary thyristor to disconnect the starting winding, and the main thyristor remains turned on.

[0035] Specifically, when the motor has just finished starting and begins running, the MCU continues to monitor its current and voltage waveforms. During this period, the secondary thyristor remains on, ensuring that the starting winding remains connected to the circuit and provides additional support for the motor. However, as the motor gradually accelerates and stabilizes, its operating characteristics will change. For example, the motor current will gradually decrease from its initial high value and stabilize, and the voltage waveform will also become smoother. The MCU can use data provided by the power metering chip to determine whether the motor has reached a stable operating state. In a specific example, this determination is made based on the changing trends of the current and voltage waveforms and whether they reach a preset stability threshold, such as a current fluctuation range of ±5% and a voltage fluctuation range of ±2%. The stability threshold can be adjusted based on the specific application scenario and motor characteristics, but this application does not specify this. If the MCU determines that the motor is running stably, it will send a signal to shut off the secondary thyristor, thereby disconnecting the starting winding and allowing the motor to continue operating solely on the main winding.

[0036] The decision to disconnect the start winding after the motor reaches steady-state operation is primarily based on efficiency and equipment protection considerations. First, the start winding is designed to provide additional torque support during the initial startup phase, helping the motor overcome resistance at standstill. Once the motor reaches a certain speed and enters steady-state operation, the start winding's function becomes unnecessary. Keeping the start winding connected at this point not only wastes energy but also increases unnecessary losses. Therefore, promptly disconnecting the start winding can significantly improve overall system efficiency and reduce energy consumption. Second, from an equipment protection perspective, leaving the start winding connected for extended periods can damage the motor and other electrical components. Since the start winding is optimized for high starting currents, leaving it connected during steady-state operation can cause overheating or other electrical failures. Disconnecting the start winding immediately after the motor reaches steady-state operation effectively avoids these problems and extends equipment life.

[0037] In one embodiment, during the operation phase, the MCU control unit receives circuit parameters collected by the electricity metering chip, and determines whether there is an abnormality based on the circuit parameters collected by the electricity metering chip; after receiving the abnormal signal, the MCU control unit disconnects the main thyristor.

[0038] Specifically, after the motor successfully starts and enters normal operation, the MCU continuously receives data from the power metering chip. This data includes key parameters such as current, voltage, power, and temperature. By monitoring these parameters in real time, the MCU can promptly detect any deviations from the normal operating range. For example, if the motor current suddenly exceeds the set safety threshold or the voltage fluctuates abnormally, these may be signs of a potential fault. Furthermore, excessively high temperatures may also indicate a cooling problem or other potential risks in the system. In this case, the MCU takes immediate action to cut off power to the motor by disconnecting the main thyristor, preventing further damage.

[0039] In summary, the single-phase asynchronous motor starting control circuit based on an MCU and dual thyristors (SCRs) provided in this application integrates an advanced MCU control unit, primary and secondary thyristors (SCRs), and an energy metering chip, providing a more intelligent and efficient single-phase asynchronous motor starting solution. The dual-path control strategy of the primary and secondary SCRs is designed to precisely manage the motor starting process: the primary SCR controls the live wire, ensuring safe operation of the entire circuit; the secondary SCR specifically controls the connection and disconnection of the starter winding, achieving precise control of the starting time, thus completely replacing the functions of a traditional PTC starter. Furthermore, the introduction of the energy metering chip enables the system to monitor key parameters such as current, voltage, and power in real time, and provides multiple protection mechanisms such as overcurrent, overvoltage, and overtemperature, significantly improving system safety and stability. Leveraging the powerful processing capabilities of the MCU, the adaptive starting algorithm dynamically adjusts the starting current, start time, and trigger angle according to different load conditions, ensuring a smooth and energy-efficient motor starting process under various operating conditions. This solution supports remote configuration and optimization via the MCU, making it suitable for modern smart home appliances and IoT devices, providing users with greater flexibility and convenience. In this way, the problems of slow response speed, high energy consumption and poor reliability in the existing technology are solved, and the motor starting process is highly controllable and adaptable, thereby improving the starting reliability, protection capability and response speed, and realizing the upgrade of single-phase asynchronous motor starting technology.

[0040] Furthermore, the single-phase asynchronous motor starting control technology proposed in this application is particularly suitable for motor drive requirements in household appliances and industrial equipment, such as compressor drives in appliances like air conditioners and refrigerators. By adopting the technical solution of this invention, not only can more precise and efficient motor control be achieved, but the performance and service life of these devices can also be significantly improved, thus possessing important practical application value.

[0041] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0042] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0043] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A single-phase asynchronous motor starting control circuit based on MCU and dual thyristor, characterized in that: include: An MCU control unit, a main thyristor, a secondary thyristor, an electricity metering chip, and a protection circuit; the main thyristor is electrically connected to the MCU control unit for controlling the on / off of the live wire; the secondary thyristor is electrically connected to the MCU control unit for controlling the on / off of the start winding; the electricity metering chip is electrically connected to the MCU control unit for monitoring circuit parameters; the protection circuit is connected to the MCU control unit for providing circuit protection; during the startup phase, the MCU control unit first sends a trigger signal to the secondary thyristor to put the secondary thyristor in a conducting state, and the secondary thyristor connects to the start winding to provide additional starting torque for the single-phase asynchronous motor; After the starting conditions are met, the MCU control unit sends a trigger signal to the main thyristor to put the main thyristor into a conducting state, and the main thyristor connects the live wire to enable the single-phase asynchronous motor to enter a normal operating state; Among them, after the startup conditions are met, the MCU control unit then sends a trigger signal to the main thyristor to put the main thyristor into a conducting state, including: collecting motor current and motor voltage through the electricity metering chip to obtain a time series of motor current; calculating a current rise / fall rate value based on the time series of the motor current; judging the load type based on a comparison between the current rise / fall rate value and a preset threshold, the load type including light load, medium load and heavy load; based on the load type, the MCU control unit sets an initial trigger angle of the main thyristor.

2. The single-phase asynchronous motor starting control circuit based on MCU and dual thyristor according to claim 1, characterized in that: The start condition is a fixed delay.

3. The single-phase asynchronous motor starting control circuit based on MCU and dual thyristor according to claim 1, characterized in that: The starting condition is that the AC power supply voltage passes through zero.

4. The single-phase asynchronous motor starting control circuit based on MCU and dual thyristor according to claim 3, characterized in that: When the load type is light load, the initial trigger angle of the main thyristor is 80°; when the load type is medium load, the initial trigger angle of the main thyristor is 110°; when the load type is heavy load, the initial trigger angle of the main thyristor is 130°.

5. The single-phase asynchronous motor starting control circuit based on MCU and dual thyristor according to claim 1, characterized in that: During the operation stage, the MCU control unit determines whether the single-phase asynchronous motor has reached a stable operating state through the circuit parameters collected by the electricity metering chip. After determining that the single-phase asynchronous motor has reached a stable operating state, the MCU control unit sends a signal to turn off the auxiliary thyristor to disconnect the starting winding, and the main thyristor remains turned on.

6. The single-phase asynchronous motor starting control circuit based on MCU and dual thyristor according to claim 5, characterized in that: During the operation phase, the MCU control unit receives the circuit parameters collected by the electricity metering chip and determines whether there is an abnormality based on the circuit parameters collected by the electricity metering chip; After receiving the abnormal signal, the MCU control unit disconnects the main thyristor.

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