Single-phase split-phase motor starting control circuit and adaptive capacitor thereof

Abstract

The invention relates to a single-phase split-phase motor starting control circuit and an adaptive capacitor thereof. The circuit comprises a signal acquisition part, a CPU processing part, a power supply part and a driving part, the power supply part is respectively connected with each part and is used for supplying power; the signal acquisition part is connected with the CPU processing part and is used for acquiring current, voltage and phase signals, performing CPU operation based on the acquired signals and generating instruction signals for controlling the driving part; three parallel / series capacitors and corresponding control circuits are adopted, motor operation parameters are collected in real time, a CPU judges the state of the motor according to a preset strategy and controls capacitor switches, all the capacitors are connected in parallel in the starting stage to provide large starting torque, and series-parallel combination is conducted in the stable operation process to reduce the capacitance value and improve the efficiency. And the capacitor is cut off to protect the motor when locked-rotor occurs.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control circuits, and in particular to a single-phase split-phase motor starting control circuit and a capacitor adapted thereto. Background Art

[0002] See attached Figure 1 As shown, currently on the market, mechanical switches are equipped with dual capacitors. The existing dual capacitor technology takes up a large space, is costly and has no lifespan guarantee. Mechanical switches are also difficult to install, have high requirements on workers, and the contacts are prone to sparking and have a short lifespan.

[0003] Moreover, single-phase split-phase motors face a complex technical contradiction during the starting, operation and protection process. When the motor starts, a large capacitor is required to provide sufficient starting torque, but this conflicts with the requirement of a small capacitor to improve efficiency during stable operation. At the same time, the motor may also encounter abnormal conditions such as stalling, which requires corresponding protection measures. There is a trade-off relationship between the requirements of these different operating stages, which is difficult to meet with a single fixed capacitor configuration. The deeper problem lies in how to accurately judge the operating state of the motor in real time and dynamically adjust the capacitor configuration accordingly. This involves real-time monitoring and analysis of the motor's operating parameters, including current, voltage, speed, load and other dimensions. In actual applications, the operating environment and load of the motor may change frequently, which requires the control to respond quickly and make appropriate adjustments, while also considering the problems that may arise from frequent switching. Summary of the invention

[0004] The main purpose of the present invention is to provide a single-phase split-phase motor starting control circuit and a capacitor adapted thereto. The single-phase split-phase motor starting control circuit includes a signal acquisition part, a CPU processing part, a power supply part and a drive part; The power supply part is connected to each part respectively for supplying power; The signal acquisition part is connected to the CPU processing part to acquire current, voltage and phase signals, and performs CPU calculation based on the acquired signals to generate a command signal for controlling the driving part; The driving part includes a first capacitor C1, a second capacitor C2, a third capacitor C3 and a first switch K1, a second switch K2, and a third switch K3, wherein: The first pin of the first capacitor C1 is connected to the power supply part and the first pin of the first switch K1, and the second pin of the first capacitor C1 is connected to the first pin of the second switch K2 and the first pin of the second capacitor C2; The second pin of the second capacitor C2 is respectively connected to the second pin of the first switch K1 and the first pin of the third switch K3; The first pin of the third capacitor C3 is respectively connected to the second pin of the first switch K1, the second pin of the second capacitor C2, and the first pin of the third switch K3; The third pins of the first switch K1 , the second switch K2 and the third switch K3 are connected to the CPU processing part respectively.

[0005] Furthermore, a control method of a motor starting control circuit includes: S1, detect motor power-on; S2, closing the first switch K1, the second switch K2 and the third switch K3, so that the first capacitor C1, the second capacitor C2 and the third capacitor C3 are connected in parallel; S3, using the signal acquisition part to acquire a first drive signal in the drive part, where the first drive signal includes a current, a voltage and a phase signal; S4, judging whether the current motor reaches the disconnection point based on the first drive signal, if not, returning to execute S2; S5, if yes, then disconnect the first switch K1 and the second switch K2, and close the third switch K3, so that the first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in series in sequence; S6, using the signal acquisition part to acquire a second drive signal in the drive part, where the second drive signal includes a current, a voltage and a phase signal; S7, judging whether the current motor is stalled based on the second driving signal, if not, returning to S5; S8: If yes, turn off the third switch K3 and return to execute S2.

[0006] Further, in the step of determining whether the current motor has reached the disconnection point based on the first drive signal, the method by which the CPU processing part determines whether the motor has reached the disconnection point is: Calculate the slopes of the current signal and the voltage signal. If the current slope changes to a maximum value and the current value is less than 70% of the maximum starting current, and the voltage value is greater than 80% of the rated voltage, it is determined that the disconnection point has been reached.

[0007] Further, in the step of determining whether the current motor is stalled based on the second drive signal, the method by which the CPU processing part determines whether the motor is stalled is: If the voltage value drops below 60% of the rated voltage and the current value is greater than 70% of the maximum starting current, the motor is judged to be stalled and all capacitors are controlled to restart.

[0008] Further, the CPU processes a portion of the configuration optimization model; The optimization model records the rate of change of the main winding current and the auxiliary winding voltage and the motor speed when the motor starts; The optimization model records the change rate of the main winding current and the auxiliary winding voltage and the motor speed when the motor load increases; The recorded data is processed by the optimization model to optimize the threshold determination of the first drive signal and the second drive signal by the CPU processing part.

[0009] Furthermore, the recorded data is processed by the optimization model to optimize the CPU processing part for determining the thresholds of the first drive signal and the second drive signal in the following manner: Calculating a current slope threshold, a voltage threshold, and a stall judgment threshold of a CPU processing part based on the recorded data; The judgment standard thresholds of the first drive signal and the second drive signal are modified according to the calculated thresholds.

[0010] Furthermore, the algorithm for calculating the current slope threshold, voltage threshold and stall judgment threshold of the CPU processing part based on the recorded data is: The current slope judgment formula is a real-time optimization of the threshold value of the current signal in the first drive signal;

[0011] Wherein, dI / dt represents the current change rate, I(t) represents the current value at time t, I_max represents the maximum starting current, k1 is the judgment coefficient 0.7, and Δt is the sampling time interval; The voltage threshold judgment formula is to optimize the threshold of the voltage signal in the first drive signal in real time;

[0012] Wherein, V_th represents the voltage threshold, V_rated represents the rated voltage, V_measured represents the measured voltage, and 0.8 is the voltage judgment coefficient; The stall judgment formula is a real-time optimization of the threshold value of the voltage signal in the second drive signal;

[0013] Wherein, η represents the voltage ratio, V_measured represents the measured voltage, V_rated represents the rated voltage, and 0.6 is the stall judgment coefficient.

[0014] Furthermore, the signal acquisition part acquires current, voltage and phase signals at a frequency of 100 times per second.

[0015] Furthermore, the first switch K1, the second switch K2 and the third switch K3 are thyristor trigger modules.

[0016] The present invention further provides a capacitor, wherein the capacitor is configured with the above-mentioned single-phase split-phase motor starting control circuit, and a control method executed by the single-phase split-phase motor starting control circuit.

[0017] The single-phase split-phase motor starting control circuit and the capacitor adapted thereto provided by the present invention have the following beneficial effects: In view of the problems that a large capacitor is needed to provide starting torque when the motor starts, a small capacitor is needed to improve efficiency during stable operation, and stalling may occur, the present invention adopts three parallel capacitors and corresponding control circuits. By collecting the motor operating parameters in real time, the CPU judges the motor state and controls the capacitor switch according to the preset strategy. All capacitors are connected in parallel to provide a large starting torque during the startup phase, and the series-parallel combination is used to reduce the capacitance value to improve efficiency during stable operation. When stalling occurs, the capacitor is cut off to protect the motor. The present invention also judges the motor speed load by analyzing the changes in the current and voltage signals, providing a basis for the control strategy. The scheme realizes the intelligent control of motor starting, operation, and protection, and improves the starting performance, operating efficiency, and reliability of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a circuit diagram of a mechanical switch equipped with dual capacitors in the prior art; Figure 2 1 is a circuit diagram of a single-phase split-phase motor starting control circuit in one embodiment of the present invention; Figure 3 It is a flow chart of a CPU circuit control method of a single-phase split-phase motor starting control circuit in one embodiment of the present invention; Figure 4 It is a voltage and current test data diagram of a single-phase split-phase motor starting control circuit in one embodiment of the present invention.

[0019] Figure 5 It is a voltage and current test data diagram of a single-phase split-phase motor starting control circuit in another embodiment of the present invention.

[0020] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] See attached Figure 2 As shown, the present invention proposes a single-phase split-phase motor starting control circuit, including a signal acquisition part, a CPU processing part, a power supply part and a driving part; The power supply part is connected to each part respectively for supplying power; The signal acquisition part is connected to the CPU processing part to acquire current, voltage and phase signals, and performs CPU calculation based on the acquired signals to generate a command signal for controlling the driving part; The driving part includes a first capacitor C1, a second capacitor C2, a third capacitor C3 and a first switch K1, a second switch K2, and a third switch K3, wherein: The first pin of the first capacitor C1 is connected to the power supply part and the first pin of the first switch K1, and the second pin of the first capacitor C1 is connected to the first pin of the second switch K2 and the first pin of the second capacitor C2; The second pin of the second capacitor C2 is respectively connected to the second pin of the first switch K1 and the first pin of the third switch K3; The first pin of the third capacitor C3 is respectively connected to the second pin of the first switch K1, the second pin of the second capacitor C2, and the first pin of the third switch K3; The third pins of the first switch K1 , the second switch K2 and the third switch K3 are connected to the CPU processing part respectively.

[0023] In one embodiment, the current and voltage signals of the single-phase split-phase motor are collected, and the current and voltage change curves during the motor startup process are obtained through the signal acquisition and detection circuit. According to the obtained current and voltage change curves, it is determined whether the current reaches 70% of the maximum current at startup, and whether the voltage reaches about 80% of the maximum voltage. If the conditions are met, it is determined that the motor speed reaches about 75% of the rated speed at this time. When the motor speed reaches about 75% of the rated speed, the CPU control circuit issues an instruction to control the drive circuit to disconnect the secondary winding to avoid the phenomenon of disconnection too early resulting in insufficient torque or disconnection too late resulting in inability to disconnect. During the operation of the motor, the current and voltage signals of the motor are continuously collected, and the current and voltage change curves when the motor is running are obtained through the signal acquisition and detection circuit. According to the current and voltage change curves when the motor is running, it is determined whether the voltage drops to about 60%, and whether the current is greater than 70% of the starting current. If the conditions are met, it is determined that the motor speed drops from the rated speed. When it is determined that the motor speed drops from the rated speed, the CPU control circuit issues an instruction to control the drive circuit to reconnect the secondary winding to ensure that the motor can maintain normal operation when the load increases. The power supply circuit provides a stable working voltage for the entire control to ensure the normal operation of the signal acquisition and detection circuit, the CPU control circuit and the drive circuit. The first capacitor C1, the second capacitor C2 and the third capacitor C3 connected in parallel are used as the starting capacitor. The switching of the capacitors is controlled by the CPU control circuit and the drive circuit to optimize the current and voltage characteristics during the motor starting process. According to the actual working state of the motor, the control strategy and parameters are adjusted in real time through the CPU control circuit, such as adjusting the current and voltage thresholds, optimizing the timing of capacitor switching, etc., to improve the reliability and efficiency of the motor starting and operation.

[0024] Specifically, the signal acquisition and detection circuit collects the current and voltage change curves during the motor startup process, for example, the sampling frequency is 1kHz and the resolution is 12 bits. According to the collected data, it is determined whether the current reaches 70% of the maximum current at startup (such as 5A), and whether the voltage reaches about 80% of the maximum voltage (such as 220V). If the conditions are met, it is determined that the motor speed reaches about 75% of the rated speed (such as 1500rpm). When the above conditions are met, the CPU control circuit issues an instruction to control the drive circuit to disconnect the secondary winding through a relay or a solid-state switch. During the operation of the motor, the current and voltage signals of the motor are continuously collected at intervals of 100ms. When the voltage drops to about 60% (such as 132V) and the current is greater than 70% of the starting current (such as 3.5A), it is determined that the motor speed drops from the rated speed, and the CPU control circuit issues an instruction to control the drive circuit to reconnect the secondary winding. The power supply circuit uses an AC-DC module to output a 24V DC voltage, which is converted to 5V and 3.3V by a DC-DC module to power each circuit module. The starting capacitor uses three 100uF / 450V electrolytic capacitors in parallel, which are switched on and off by relays or solid-state switches. The CPU control circuit is based on the PID algorithm. According to the actual working state of the motor, the control parameters are adjusted in real time, such as adjusting the current threshold to 80% of the rated current and the voltage threshold to 75% of the rated voltage, optimizing the timing of capacitor switching and improving the reliability and efficiency of motor starting and operation.

[0025] See attached Figure 3 As shown, the control method of the motor starting control circuit includes: S1, detect motor power-on; S2, closing the first switch K1, the second switch K2 and the third switch K3, so that the first capacitor C1, the second capacitor C2 and the third capacitor C3 are connected in parallel; S3, using the signal acquisition part to acquire a first drive signal in the drive part, where the first drive signal includes a current, a voltage and a phase signal; S4, judging whether the current motor reaches the disconnection point based on the first drive signal, if not, returning to execute S2; S5, if yes, then disconnect the first switch K1 and the second switch K2, and close the third switch K3, so that the first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in series in sequence; S6, using the signal acquisition part to acquire a second drive signal in the drive part, where the second drive signal includes a current, a voltage and a phase signal; S7, judging whether the current motor is stalled based on the second driving signal, if not, returning to S5; S8: If yes, turn off the third switch K3 and return to execute S2.

[0026] In one embodiment, a current sensor is used to obtain the current signal of the motor, and the current signal is converted into a digital signal through an analog-to-digital conversion circuit. A voltage sensor is used to obtain the voltage signal of the motor, and the voltage signal is converted into a digital signal through an analog-to-digital conversion circuit. A phase detection circuit is used to obtain the phase signal of the motor, and the phase signal is converted into a digital signal through an analog-to-digital conversion circuit. According to the obtained current, voltage and phase digital signals, the running state of the motor is judged. If the current is greater than 300% to 700% of the no-load current and the voltage is the minimum, it is determined that the motor is in the starting stage. According to the obtained current and voltage digital signals, the running state of the motor is judged. If the current decreases from the maximum value at a certain slope and the voltage increases from the minimum value at a certain slope, it is determined that the motor is in the acceleration stage. According to the obtained current and voltage digital signals, the running state of the motor is judged. If the current and voltage reach a stable value, it is determined that the motor has reached the rated speed. According to the obtained current and voltage digital signals, the running state of the motor is judged. If the current is less than 70% of the maximum current at startup and the voltage reaches about 80% of the maximum voltage, it is determined that this is the appropriate time to disconnect the secondary winding. The motor's operating status is determined based on the acquired current and voltage digital signals. If the voltage drops to about 60% and the current is greater than 70% of the starting current, it is determined that the secondary winding needs to be reconnected. The acquired and determined motor operating status digital signal is transmitted to the CPU control circuit, which performs corresponding control operations based on the motor operating status signal.

[0027] Specifically, a Hall current sensor is used to obtain the current signal of the motor. The range of the sensor is 0-50A, and the output voltage signal is 0-5V. The voltage signal is converted into a digital signal through a 12-bit ADC analog-to-digital conversion circuit. A resistor voltage divider circuit is used to obtain the voltage signal of the motor. The input voltage range of the circuit is 0-500V, and the output voltage signal is 0-5V. The voltage signal is converted into a digital signal through a 12-bit ADC analog-to-digital conversion circuit. A zero-crossing detection circuit is used to obtain the phase signal of the motor. The circuit can detect the zero-crossing point of the voltage signal, output a 5V pulse signal, and convert the pulse signal into a digital signal through an external interrupt. According to the obtained current, voltage and phase digital signals, the running state of the motor is judged. If the current is greater than 500% of the no-load current and the voltage is less than 20% of the rated voltage, it is determined that the motor is in the starting stage. According to the obtained current and voltage digital signals, the running state of the motor is judged. If the current drops from the maximum value to 50% within 0.5s and the voltage rises from the minimum value to 80% within 0.5s, it is determined that the motor is in the acceleration stage. According to the acquired current and voltage digital signals, the running state of the motor is judged. If the current and voltage change less than 1% within 0.1s, it is determined that the motor has reached the rated speed. According to the acquired current and voltage digital signals, the running state of the motor is judged. If the current is less than 70% of the maximum current at startup and the voltage reaches 80% of the maximum voltage, it is determined that this is the right time to disconnect the secondary winding. According to the acquired current and voltage digital signals, the running state of the motor is judged. If the voltage drops to 60% and the current is greater than 70% of the starting current, it is determined that the secondary winding needs to be reconnected. The acquired and judged motor running state digital signal is transmitted to the CPU control circuit through the SPI bus, and the CPU control circuit controls the relay to disconnect or connect the secondary winding according to the motor running state signal.

[0028] See Figure 4 as well as Figure 5 As shown, in one embodiment, the CPU processes a portion of the configuration optimization model; The optimization model records the rate of change of the main winding current and the auxiliary winding voltage and the motor speed when the motor starts; The optimization model records the change rate of the main winding current and the auxiliary winding voltage and the motor speed when the motor load increases; The recorded data is processed by the optimization model to optimize the threshold determination of the first drive signal and the second drive signal by the CPU processing part.

[0029] The method of processing the recorded data by the optimization model to optimize the CPU processing part for optimizing the threshold judgment of the first drive signal and the second drive signal is: Calculating a current slope threshold, a voltage threshold, and a stall judgment threshold of a CPU processing part based on the recorded data; The judgment standard thresholds of the first drive signal and the second drive signal are modified according to the calculated thresholds.

[0030] The algorithm for calculating the current slope threshold, voltage threshold and stall judgment threshold of the CPU processing part of the recorded data is: The current slope judgment formula is a real-time optimization of the threshold value of the current signal in the first drive signal;

[0031] Wherein, dI / dt represents the current change rate, I(t) represents the current value at time t, I_max represents the maximum starting current, k1 is the judgment coefficient 0.7, and Δt is the sampling time interval; The voltage threshold judgment formula is to optimize the threshold of the voltage signal in the first drive signal in real time;

[0032] Wherein, V_th represents the voltage threshold, V_rated represents the rated voltage, V_measured represents the measured voltage, and 0.8 is the voltage judgment coefficient; The stall judgment formula is a real-time optimization of the threshold value of the voltage signal in the second drive signal;

[0033] Wherein, η represents the voltage ratio, V_measured represents the measured voltage, V_rated represents the rated voltage, and 0.6 is the stall judgment coefficient.

[0034] The current data and voltage data of the motor when it is running are collected by sensors to obtain the initial current and voltage data. The maximum current in the initial current and voltage data and the time point when the maximum current occurs are obtained to determine the maximum current and motor start-up time at startup. The initial current and voltage data are fitted by mathematical methods to obtain the slope change of the current and voltage curve. If the slope of the current and voltage curve changes to a maximum value and the current current is less than 70% of the maximum current at startup, the voltage data at this time is extracted and the next step of calculation is performed to determine whether it has reached 80% of the maximum value of the motor starting voltage. If the voltage reaches about 80% of the maximum voltage, the time node and motor speed information at this moment are recorded to determine that the speed reaches about 75% of the rated speed. According to this time node and combined with the motor start-up time, the control instruction for disconnecting the secondary winding is determined. When the motor is running, the current and voltage data are collected in real time. If the voltage drops to about 60% of the maximum value of the motor starting voltage, the next step of current data calculation is performed to obtain the ratio information of the real-time current data and the maximum starting current. Using the ratio information obtained, if the real-time current is greater than 70% of the starting current, a control signal is generated to determine that the motor needs to reconnect the secondary winding. Based on the current, voltage and speed information obtained in the above steps, a motor operation status database is constructed, and the data recorded in the database is used as sample training data to determine the operation status of the motor under different working conditions and obtain the motor control strategy.

[0035] Specifically, the current and voltage data of the motor are collected in real time through the Hall sensor installed on the motor. Assume that the initial current is 30A and the voltage is 220V. The collected data is stored in the memory buffer, and the current data is analyzed in the frequency domain using the fast Fourier transform (FFT) algorithm to extract the fundamental component, and the maximum current at startup is determined to be 42A. Then, the voltage data is curve fitted using the least squares method to obtain the slope of the voltage over time, and it is found that the slope reaches a maximum value at t=1.5 seconds. At this time, the current is 29A, which is less than 70% of the maximum current at startup (29.4A), and the voltage is 176V, which is close to 80% of the maximum voltage of 220V (it should be noted that the maximum voltage can be between 200V and 1000V, which is determined by the capacitance value of the capacitor). The speed recorded at this moment is 1500rpm, which is about 75% of the rated speed of 2000rpm. Based on these data, the CPU control circuit generates a control instruction to disconnect the secondary winding. During the operation of the motor, current and voltage data continue to be collected. If the voltage drops to 132V (60% of 220V), the real-time current is 35A, which is greater than 70% of the starting current (29.4A), the CPU control circuit generates an instruction to reconnect the secondary winding. All collected data is stored in the motor operation status database, and machine learning algorithms such as support vector machines (SVM) are used to classify the data, establish motor operation models under different working conditions, and finally determine the motor control strategy. In this way, the CPU control circuit can accurately judge the operating status of the motor according to the preset control strategy, generate corresponding control instructions, and ensure efficient and stable operation of the motor.

[0036] The current state information of the capacitor is obtained, and the initial state of the corresponding switches K1, K2 and K3 is determined. The running state of the motor is determined by comparing the actual speed of the motor with the rated speed. If the motor is in the starting stage, the current threshold and voltage threshold for the secondary winding to be disconnected are obtained according to the slope change, historical test data and motor current. If the motor current is less than 70% of the maximum current at startup and the voltage reaches 80% of the maximum voltage, it is determined that this is the secondary winding disconnection point. According to the motor load condition and historical data, the relevant parameters of the speed drop caused by the increase in load when the motor is running are obtained. By reading the current and voltage data when the motor is running and the current and voltage at the rated speed, the situation of the motor speed reduction at this time is determined. If the voltage drops to 60% of the maximum voltage and the current is greater than 70% of the starting current, the secondary winding reconnection signal is obtained. According to the judgment results of the above steps, the control instructions of switches K1, K2 and K3 are generated, and the specific execution strategy for driving the capacitor on and off is obtained. The control instructions are used to trigger the drive circuit to execute the actions of switches K1, K2, and K3 to obtain control of the capacitor on and off.

[0037] Specifically, the signal acquisition part acquires current, voltage and phase signals at a frequency of 100 times per second. The first switch K1, the second switch K2 and the third switch K3 are thyristor trigger modules.

[0038] In one embodiment, the operating state information of the single-phase split-phase motor is obtained to determine whether the motor is powered on. If it is powered on, the circuit signal is collected and powered by AC alternating current to determine the voltage and current information. According to the voltage and current data obtained, the current information at the current moment is judged to determine the stage of the motor. If the motor is in the startup stage, the CPU is used to process information according to the algorithm to obtain the control signals of switches K1, K2, and K3. According to the control signal obtained, the trigger circuit of the thyristor is driven to obtain the switch combination in which switches K1 and K2 are closed and switch K3 is disconnected. This switch combination is used to control the capacitors C1, C2, and C3 to connect, and obtain a circuit structure in which three capacitors are connected in parallel. If the motor is in the startup stage, three capacitors are used in parallel to provide a capacitance value to obtain a larger capacitance. According to the total capacitance data after parallel connection, the torque calculation formula in physics is used to obtain the torque size of the motor at this time. According to the torque size of the motor at this time and the information of the parallel connection of the three capacitors, the operating state information of the new capacitor and its supporting control circuit is obtained by signal acquisition and detection.

[0039] Specifically, when the single-phase split-phase motor is powered on, the current sensor first detects that the current value is 10A, and the voltage sensor shows that the voltage is 220V. These data are transmitted to the CPU in real time for processing. The CPU uses a preset starting current threshold algorithm, sets the starting current threshold to 8A, and determines that the current current 10A is greater than the threshold, and determines that the motor is in the starting stage. Subsequently, the CPU generates a control signal for the closing of switches K1 and K2 and the disconnection of K3 according to the built-in control algorithm. The signal is transmitted to the thyristor trigger module through the drive circuit, triggering the thyristor to turn on, so that switches K1 and K2 are closed and K3 is disconnected. At this time, capacitors C1, C2, and C3 are connected in parallel, and the total capacitance value reaches 100μF. According to the capacitor parallel formula C total = C1 + C2 + C3, where C1 = C2 = C3 = 33.3μF. The capacitance value of the capacitors after parallel connection is calculated by the motor starting torque formula T = K × C × V^2 (K is a constant, V is a voltage), and the starting torque is 50Nm, which meets the requirements of the larger torque required for motor starting. The motor operation status is continuously monitored in real time through the current and voltage sensors. If the current drops below 5A and the voltage stabilizes at 220V, the CPU determines that the motor has entered the normal operation stage, generates a new control signal, disconnects K1 and K2, and closes K3, so that capacitors C1 and C2 are connected in series, and C3 works alone. The total capacitance value is reduced to 50μF, which improves the capacitor withstand voltage and ensures the stable operation of the motor. During the whole process, the CPU continuously collects and analyzes current and voltage data, and dynamically adjusts the switch state according to the preset algorithm to ensure that the motor obtains appropriate capacitor support at different stages, achieving efficient startup and stable operation.

[0040] The present invention also proposes a capacitor, the capacitor is configured with the above-mentioned single-phase split-phase motor starting control circuit, and the control method executed by the single-phase split-phase motor starting control circuit. The capacitor is used to solve the problems that a large capacitor is needed to provide starting torque when the motor starts, a small capacitor is needed to improve efficiency during stable operation, and stalling may occur. The present invention adopts three parallel capacitors and corresponding control circuits. By collecting the motor operating parameters in real time, the CPU judges the motor state and controls the capacitor switch according to the preset strategy. All capacitors are connected in parallel to provide a large starting torque during the starting phase, and the series-parallel combination is used to reduce the capacitance value to improve efficiency during stable operation. When stalling occurs, the capacitor is cut off to protect the motor. The present invention also judges the motor speed load by analyzing the changes in the current and voltage signals, providing a basis for the control strategy. The scheme realizes the intelligent control of motor starting, operation, and protection, and improves the starting performance, operating efficiency, and reliability of the motor.

[0041] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0042] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A single-phase split-phase motor starting control circuit, characterized in that: It includes signal acquisition part, CPU processing part, power supply part and driving part; The power supply part is connected to each part respectively for supplying power; The signal acquisition part is connected to the CPU processing part to acquire current, voltage and phase signals, and performs CPU calculation based on the acquired signals to generate a command signal for controlling the driving part; The driving part includes a first capacitor C1, a second capacitor C2, a third capacitor C3 and a first switch K1, a second switch K2, and a third switch K3, wherein: The first pin of the first capacitor C1 is connected to the power supply part and the first pin of the first switch K1, and the second pin of the first capacitor C1 is connected to the first pin of the second switch K2 and the first pin of the second capacitor C2; The second pin of the second capacitor C2 is respectively connected to the second pin of the first switch K1 and the first pin of the third switch K3; The first pin of the third capacitor C3 is respectively connected to the second pin of the first switch K1, the second pin of the second capacitor C2, and the first pin of the third switch K3; The third pins of the first switch K1 , the second switch K2 and the third switch K3 are connected to the CPU processing part respectively.

2. The single-phase split-phase motor starting control circuit according to claim 1, characterized in that: A control method for a motor starting control circuit, comprising: S1, detect motor power-on; S2, closing the first switch K1, the second switch K2 and the third switch K3, so that the first capacitor C1, the second capacitor C2 and the third capacitor C3 are connected in parallel; S3, using the signal acquisition part to acquire a first drive signal in the drive part, where the first drive signal includes a current, a voltage and a phase signal; S4, judging whether the current motor reaches the disconnection point based on the first drive signal, if not, returning to execute S2; S5, if yes, then disconnect the first switch K1 and the second switch K2, and close the third switch K3, so that the first capacitor C1, the second capacitor C2, and the third capacitor C3 are connected in series in sequence; S6, using the signal acquisition part to acquire a second drive signal in the drive part, where the second drive signal includes a current, a voltage and a phase signal; S7, judging whether the current motor is stalled based on the second driving signal, if not, returning to S5; S8: If yes, turn off the third switch K3 and return to execute S2.

3. The single-phase split-phase motor starting control circuit according to claim 2, characterized in that: In the step of judging whether the current motor has reached the disconnection point based on the first drive signal, the method by which the CPU processing part judges whether the motor has reached the disconnection point is: Calculate the slopes of the current signal and the voltage signal. If the current slope changes to a maximum value and the current value is less than 70% of the maximum starting current, and the voltage value is greater than 80% of the rated voltage, it is determined that the disconnection point has been reached.

4. The single-phase split-phase motor starting control circuit according to claim 2, characterized in that: In the step of determining whether the current motor is stalled based on the second drive signal, the method by which the CPU processing part determines whether the motor is stalled is: If the voltage value drops below 60% of the rated voltage and the current value is greater than 70% of the maximum starting current, the motor is judged to be stalled and all capacitors are controlled to restart.

5. The single-phase split-phase motor starting control circuit according to claim 2, characterized in that: The CPU processing part configures an optimization model; The optimization model records the rate of change of the main winding current and the auxiliary winding voltage and the motor speed when the motor starts; The optimization model records the change rate of the main winding current and the auxiliary winding voltage and the motor speed when the motor load increases; The recorded data is processed by the optimization model to optimize the threshold determination of the first drive signal and the second drive signal by the CPU processing part.

6. The single-phase split-phase motor starting control circuit according to claim 5, characterized in that: The method of processing the recorded data by the optimization model to optimize the CPU processing part for optimizing the threshold judgment of the first drive signal and the second drive signal is: Calculating a current slope threshold, a voltage threshold, and a stall judgment threshold of a CPU processing part based on the recorded data; The judgment standard thresholds of the first drive signal and the second drive signal are modified according to the calculated thresholds.

7. The single-phase split-phase motor starting control circuit according to claim 6, characterized in that: The algorithm for calculating the current slope threshold, voltage threshold and stall judgment threshold of the CPU processing part based on the recorded data is: The current slope judgment formula is a real-time optimization of the threshold value of the current signal in the first drive signal; Wherein, dI / dt represents the current change rate, I(t) represents the current value at time t, I_max represents the maximum starting current, k1 is the judgment coefficient 0.7, and Δt is the sampling time interval; The voltage threshold judgment formula is to optimize the threshold of the voltage signal in the first drive signal in real time; Wherein, V_th represents the voltage threshold, V_rated represents the rated voltage, V_measured represents the measured voltage, and 0.8 is the voltage judgment coefficient; The stall judgment formula is a real-time optimization of the threshold value of the voltage signal in the second drive signal; Wherein, η represents the voltage ratio, V_measured represents the measured voltage, V_rated represents the rated voltage, and 0.6 is the stall judgment coefficient.

8. The single-phase split-phase motor starting control circuit according to claim 1, characterized in that: The signal acquisition part acquires current, voltage and phase signals at a frequency of 100 times per second.

9. The single-phase split-phase motor starting control circuit according to claim 1, characterized in that: The first switch K1, the second switch K2 and the third switch K3 are thyristor trigger modules.

10. A capacitor, characterized in that: The capacitor is configured with the single-phase split-phase motor starting control circuit described in any one of claims 1-9, and the control method executed by the single-phase split-phase motor starting control circuit.

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