Control circuit and control method of single-phase alternating current permanent magnet synchronous motor

Abstract

The application discloses a control circuit and a control method of a single-phase alternating current permanent magnet synchronous motor. The control circuit of the single-phase alternating current permanent magnet synchronous motor comprises a power supply module, the power supply module comprises a transformer, a first power supply unit and a second power supply unit, the transformer comprises a first secondary end and a second secondary end, the first power supply unit and the second power supply unit are electrically connected to the first secondary end and the second secondary end, a driving module comprises a first release end, a second release end, a first input end and a second input end, the first input end is electrically connected to the first power supply unit, the second input end is electrically connected to the second power supply unit, and the first release end and the second release end are electrically connected to the first secondary end and the second secondary end. In this way, by electrically connecting the first release end and the second release end of the driving module to the first secondary end and the second secondary end of the transformer, the energy of the counter electromotive force is absorbed or transmitted through the transformer, and potential interference or damage of the counter electromotive force to a reference ground circuit is avoided.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a control circuit and control method for a single-phase AC permanent magnet synchronous motor. Background Technology

[0002] Single-phase AC permanent magnet synchronous motors are widely used in home appliances, power tools, electric vehicles, and other fields due to their high efficiency, low noise, and excellent control performance. However, in practical applications, motor control and energy efficiency management still face many challenges, especially in dealing with the back electromotive force (BEMF) generated during motor operation and shutdown.

[0003] When the motor is off, to prevent back EMF from damaging the circuit and the motor itself, a common approach in related technologies is to manage the back EMF using a resistor-capacitor (RC) snubber circuit. This involves using a parallel network of resistors and capacitors to absorb the energy of the back EMF. This method temporarily stores the voltage spikes generated by the back EMF through the capacitor, and then gradually dissipates the energy as heat through the resistor.

[0004] However, the relevant technical solutions have the following drawbacks: the energy contained in the back electromotive force can only be dissipated as heat through the resistance, and its energy release path is singular and inefficient, resulting in the energy not being released effectively. Summary of the Invention

[0005] The main purpose of the invention is to propose a control circuit for a single-phase AC permanent magnet synchronous motor, which aims to solve the problem that the energy contained in the back EMF cannot be effectively released.

[0006] To achieve the above objectives, the invention proposes a control circuit for a single-phase AC permanent magnet synchronous motor, which includes:

[0007] A power supply module, comprising a transformer, a first power supply unit, and a second power supply unit, wherein the transformer comprises a primary terminal and a secondary terminal, and the first power supply unit and the second power supply unit are both electrically connected to the primary terminal and the secondary terminal;

[0008] The driving module includes a first release terminal, a second release terminal, a first input terminal, and a second input terminal. The first input terminal is electrically connected to the first power supply unit, and the second input terminal is electrically connected to the second power supply unit. The first release terminal and the second release terminal are respectively electrically connected to the first stage terminal and the second stage terminal. The first release terminal and the second release terminal are used to release back electromotive force.

[0009] In some embodiments, the driver module further includes:

[0010] A first switching unit, the first switching unit includes a first connection terminal and a second connection terminal, the first connection terminal is used to electrically connect to the motor, and the second connection terminal is the first release terminal;

[0011] The second switching unit includes a third connection terminal and a fourth connection terminal. The third connection terminal is electrically connected to the motor, and the fourth connection terminal is the second release terminal.

[0012] A first transient diode is electrically connected between the motor and the second connection terminal.

[0013] The second transient diode is electrically connected between the motor and the fourth connection terminal.

[0014] In some embodiments, the first switching unit includes a first switching transistor, the drain of the first switching transistor is electrically connected to the motor through the first connection terminal, and the source is electrically connected to the first release terminal;

[0015] The second switching unit includes a second switching transistor, the drain of which is electrically connected to the motor through the third connection terminal, and the source of which is electrically connected to the second release terminal.

[0016] In some embodiments, the first power supply unit includes a first voltage regulator, which includes a third input terminal, a first output terminal, and a first common terminal. The third input terminal is electrically connected to the first stage terminal, the first output terminal is electrically connected to the first input terminal, and the first common terminal is electrically connected to the second stage terminal.

[0017] In some embodiments, the first power supply unit further includes a first half-wave rectifier, and the first stage terminal is electrically connected to the third input terminal via the first half-wave rectifier.

[0018] In some embodiments, the second power supply unit includes a second voltage regulator, which includes a fourth input terminal, a second output terminal, and a second common terminal. The second input terminal is electrically connected to the second stage terminal, the second output terminal is electrically connected to the second input terminal, and the second common terminal is electrically connected to the first stage terminal.

[0019] In some embodiments, the second power supply unit further includes a second half-wave rectifier, and the second stage terminal is electrically connected to the fourth input terminal via the second half-wave rectifier.

[0020] In some embodiments, the system further includes a main control module, which includes a detection terminal; the control circuit of the single-phase AC permanent magnet synchronous motor further includes a zero-point detection module, which includes a first resistor and a second resistor, one end of the first resistor is electrically connected to the first stage terminal, the other end of the first resistor is grounded after passing through the second resistor, and the detection terminal is electrically connected to the other end of the first resistor.

[0021] The invention further proposes a control method for a unidirectional AC motor, wherein the control method for the unidirectional AC motor is applied to the control circuit of the single-phase AC permanent magnet synchronous motor of the aforementioned embodiment, and the control method for the unidirectional AC motor includes:

[0022] Determine the positive and negative half-cycles of alternating current;

[0023] Obtain the initial position of the motor rotor;

[0024] Based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC power, the motor is powered during the positive or negative half-cycle of the AC power.

[0025] Real-time monitoring of the zero-crossing position of the AC current;

[0026] Disconnect the motor power supply within a preset time before the zero-crossing point.

[0027] In some embodiments, the step of supplying power to the motor during the positive or negative half-cycle of the AC current, based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC current, includes:

[0028] If the rotor position lags behind the AC phase, disconnect the motor power supply and wait for the rotor to rotate to the correct position before reconnecting the power.

[0029] If the rotor position is ahead of the AC phase, the motor power-on is delayed until the phase is matched and then the motor is powered on again.

[0030] In some embodiments, it also includes:

[0031] Real-time monitoring of motor speed to determine whether the motor rotor position signal is synchronized with the switching time of the positive and negative half-cycles of the AC power;

[0032] If the rotor position signal is detected to be out of sync with the AC half-cycle switching, disconnect the motor power supply and wait until the start of the next AC half-cycle to reassess the synchronization status before powering on.

[0033] The beneficial effects of the invention are as follows: by electrically connecting the first and second release terminals of the drive module to the first and second terminals of the transformer, effective management of the back electromotive force generated by the single-phase AC permanent magnet synchronous motor is achieved. Compared with the related technologies that simply absorb the back electromotive force and use a MOSFET for hard withstand or release it to the DC power supply ground, this invention absorbs or transfers the energy of the back electromotive force through a transformer, avoiding potential interference or damage to the reference ground circuit by the back electromotive force, and enhancing the stability and safety of the system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the module electrical connections of an embodiment of the control circuit of the single-phase AC permanent magnet synchronous motor of the present invention;

[0035] Figure 2 This is a partial circuit diagram of an embodiment of the control circuit for a single-phase AC permanent magnet synchronous motor of the present invention;

[0036] Figure 3 This is a partial circuit diagram of an embodiment of the control circuit for a single-phase AC permanent magnet synchronous motor of the present invention;

[0037] Figure 4 This is a partial circuit diagram of an embodiment of the control circuit for a single-phase AC permanent magnet synchronous motor of the present invention;

[0038] Figure 5 This is a flowchart of an embodiment of the control method for a unidirectional AC motor of the present invention;

[0039] Figure 6 This is a flowchart of an embodiment of the control method for a unidirectional AC motor of the present invention;

[0040] Figure 7 This is a flowchart of an embodiment of the control method for a unidirectional AC motor of the present invention.

[0041] Explanation of icon numbers:

[0042] 100. Power supply module;

[0043] T1, Transformer; T1A, Primary terminal; T1B, Secondary terminal;

[0044] 110, First power supply unit; U1, First voltage regulator; B3, Third input terminal; F1, First output terminal; D1, First half-wave rectifier;

[0045] 120, Second power supply unit; U2, Second voltage regulator; B4, Fourth input terminal; F2, Second output terminal; D2, Second half-wave rectifier;

[0046] 200. Driver module; A1. First release terminal; A2. Second release terminal; B1. First input terminal; B2. Second input terminal;

[0047] 210, First switching unit; A3, First connection terminal; A4, Second connection terminal; Q1, First switching transistor;

[0048] 220, Second switching unit; A5, Third connection terminal; A6, Fourth connection terminal; Q2, Second switching transistor;

[0049] TVS1, first transient diode;

[0050] TVS2, second transient diode;

[0051] 300, Main control module; ZDC, Detection terminal;

[0052] 400, Zero-point detection module; R1, First resistor; R2, Second resistor.

[0053] The realization of the invention's objective, its functional characteristics, and advantages will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0054] The solutions in the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0055] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0056] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0057] Furthermore, the use of terms such as "first" and "second" in the invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by the invention.

[0058] The core idea of ​​this invention lies in solving the technical challenge of handling back electromotive force (EMF) during the control of a single-phase AC permanent magnet synchronous motor. In traditional solutions, back EMF is typically handled through a simple absorption circuit or directly released to ground, which can easily cause circuit interference and component damage. This invention innovatively proposes a technical solution combining dual power supply and transformer-based back EMF handling. Through a clever circuit connection method, it achieves stable power supply for motor drive while effectively solving the problem of safe release of back EMF. For details, please refer to... Figure 1 The invention provides a control circuit for a single-phase AC permanent magnet synchronous motor, which includes:

[0059] The power supply module 100 includes a transformer T1, a first power supply unit 110 and a second power supply unit 120. The transformer T1 includes a primary terminal T1A and a secondary terminal T1B. The first power supply unit 110 and the second power supply unit 120 are both electrically connected to the primary terminal T1A and the secondary terminal T1B.

[0060] The drive module 200 includes a first release terminal A1, a second release terminal A2, a first input terminal B1, and a second input terminal B2. The first input terminal B1 is electrically connected to the first power supply unit 110, and the second input terminal B2 is electrically connected to the second power supply unit 120. The first release terminal A1 and the second release terminal A2 are respectively electrically connected to the first stage terminal T1A and the second stage terminal T1B. The first release terminal A1 and the second release terminal A2 are used to release the back electromotive force.

[0061] In this embodiment, the power supply module 100 is a dual-power supply module 100. Specifically, the power supply module 100 includes a transformer T1, a first power supply unit 110, and a second power supply unit 120. It can be understood that the dual-power supply module 100 utilizes the transformer T1 to provide power for the positive and negative half-cycles respectively. For example, during the positive half-cycle, the first stage terminal T1A outputs power to the first power supply unit 110, at which time the first power supply unit 110 supplies power to the drive module 200, and the second stage terminal T1B serves as a reference ground. During the negative half-cycle, the second stage terminal T1B outputs power to the second power supply unit 120, at which time the second power supply unit 120 supplies power to the drive module 200, and the first stage terminal T1A serves as a reference ground. By setting the first power supply unit 110 and the second power supply unit 120 to be connected in an interleaved manner to the primary stage T1A and the secondary stage T1B of transformer T1, it is achieved that the primary stage T1A and the secondary stage T1B of transformer T1 serve as ground references to each other in different half-cycles of single-phase AC power. This effectively avoids the ground fluctuation problem caused by the fixed virtual ground reference point in traditional technology when the grid voltage fluctuates, ensuring the stability of the drive power supply and working power supply output. As an alternative solution, transformer T1 can be in the form of a center-tapped transformer T1, a double-winding transformer T1, etc., and the power supply unit can be implemented in different ways such as a rectifier filter circuit or a switching power supply module.

[0062] In this embodiment, the drive module 200 is mainly used for the start, operation, and stop control of a single-phase AC permanent magnet synchronous motor. Specifically, it can be constructed using MOSFETs to form an H-bridge drive circuit or a half-bridge drive circuit; it can also be constructed using IGBT modules, power transistors, and other power switching devices; or it can be integrated using a dedicated motor drive chip. The first input terminal B1 is electrically connected to the first power supply unit 110, and the second input terminal B2 is electrically connected to the second power supply unit 120. This is mainly to obtain dual-path working drive power from the power supply module 100 to achieve precise control of the motor's operating state. The key innovation lies in the design of the release terminals: the first release terminal A1 and the second release terminal A2 are electrically connected to the first stage terminal T1A and the second stage terminal T1B, respectively. The first release terminal A1 and the second release terminal A2 are specifically used to release the back electromotive force generated during motor operation. This connection method allows the back electromotive force to form a loop through the secondary winding of transformer T1, rather than directly impacting the drive circuit or reference ground.

[0063] When a single-phase AC permanent magnet synchronous motor stops running, due to the principle of electromagnetic induction, the permanent magnet rotor inside the motor continues to rotate due to inertia, inducing a back electromotive force (EMF) in the stator windings. This back EMF is the induced electromotive force generated when the motor operates as a generator; its direction is opposite to the direction of the drive current, and its amplitude depends on the rotor speed and magnetic field strength. In traditional control circuits, if this back EMF is not effectively handled, it can cause voltage surges in the drive circuit and even damage power devices.

[0064] During the operation of this invention, when the motor generates a back electromotive force (EMF), this EMF is conducted to the primary winding terminal T1A and the secondary winding terminal T1B of the transformer T1 through the first release terminal A1 and the second release terminal A2 of the drive module 200, respectively. Due to the inductive characteristics of the secondary winding of the transformer T1 and the electromagnetic coupling effect of the transformer T1, the energy of the back EMF is effectively absorbed and transferred. Specifically, the back EMF forms a current loop between the primary winding terminal T1A and the secondary winding terminal T1B. This current is transferred to the primary side through the electromagnetic coupling of the transformer T1 and is eventually dissipated in the power grid or absorbed by other loads. This energy transfer process is gradual and controllable, avoiding the impact of instantaneous large currents on the drive circuit. At the same time, the impedance characteristics of the transformer T1 also play a role in current limiting protection.

[0065] The beneficial effects of this invention are as follows: by electrically connecting the first release terminal A1 and the second release terminal A2 of the drive module 200 to the first stage terminal T1A and the second stage terminal T1B of the transformer T1, effective management of the back electromotive force generated by the single-phase AC permanent magnet synchronous motor is achieved. Compared with the related technologies that simply absorb the back electromotive force and use a MOSFET to withstand it, or release it to the DC power supply ground, this invention absorbs or transfers the energy of the back electromotive force through the transformer T1, avoiding potential interference or damage to the reference ground circuit by the back electromotive force, and significantly enhancing the stability and safety of the system.

[0066] Furthermore, the dual-power supply design of this invention brings additional technical advantages: on the one hand, by alternating positive and negative half-cycle power supply, the virtual ground fluctuation problem in the traditional single-power supply scheme is eliminated, improving the stability of the power output; on the other hand, the isolation characteristics of transformer T1 provide electrical isolation protection for the drive circuit, further enhancing the system's anti-interference capability. Overall, this invention not only solves the core problem of back EMF handling, but also achieves a dual improvement in power supply stability and system reliability through an innovative circuit topology.

[0067] See Figure 2 In this embodiment, the driving module 200 further includes:

[0068] The first switching unit 210 includes a first connection terminal A3 and a second connection terminal A4. The first connection terminal A3 is used to electrically connect to the motor, and the second connection terminal A4 is a first release terminal A1.

[0069] The second switch unit 220 includes a third connection terminal A5 and a fourth connection terminal A6. The third connection terminal A5 is electrically connected to the motor, and the fourth connection terminal A6 is the second release terminal A2.

[0070] The first transient diode TVS1 is electrically connected between the motor and the second connection terminal A4.

[0071] The second transient diode TVS2 is electrically connected between the motor and the fourth connection terminal A6.

[0072] In this embodiment, the first switching unit 210 includes a first connection terminal A3 and a second connection terminal A4. The first connection terminal A3 is used to electrically connect to the single-phase AC permanent magnet synchronous motor, establishing an electrical connection path between the drive module 200 and the motor. The second connection terminal A4 is the aforementioned first release terminal A1, specifically used to release the back electromotive force. The first switching unit 210 can be constructed using power switching devices such as MOSFETs and IGBTs, and precise control of the motor current is achieved by switching the control signal on and off. When the motor is working normally, the first switching unit 210 turns on or off according to the control signal to provide the required drive current to the motor; when the motor stops or reverses, the first switching unit 210 also undertakes the functions of current freewheeling and back electromotive force guidance.

[0073] The second switching unit 220 includes a third connection terminal A5 and a fourth connection terminal A6. The third connection terminal A5 is also electrically connected to the motor, forming a double-ended connection of the motor together with the first connection terminal A3 of the first switching unit 210. The fourth connection terminal A6 is the second release terminal A2. The internal structure and working principle of the second switching unit 220 are similar to those of the first switching unit 210, and the two work together to form a complete motor drive control circuit. Through the coordinated control of the first switching unit 210 and the second switching unit 220, various operating modes such as forward and reverse rotation, speed regulation, and braking of the motor can be realized.

[0074] To protect the power devices inside the first switching unit 210 from back electromotive force (EMF) impacts, this embodiment specifically includes a first transient diode (TVS1), which is electrically connected between the motor and the second connection terminal A4. The first transient diode TVS1 has a fast response characteristic, enabling it to quickly conduct at the moment the back EMF appears, providing a low-impedance discharge path for the back EMF and preventing it from directly impacting the sensitive devices inside the first switching unit 210. Similarly, to protect the components inside the second switching unit 220, this embodiment also includes a second transient diode TVS2, which is electrically connected between the motor and the fourth connection terminal A6, providing the same protective function as the first transient diode TVS1.

[0075] The two transient diodes form a dual protection mechanism. When the motor generates back electromotive force (EMF), the first transient diode TVS1 and the second transient diode TVS2 selectively conduct according to the polarity of the back EMF, quickly guiding the back EMF energy to the corresponding release terminals, namely the second connection terminal A4 and the fourth connection terminal A6. Subsequently, the back EMF is conducted through the first release terminal A1 and the second release terminal A2 to the first stage terminal T1A and the second stage terminal T1B of transformer T1, respectively, and finally the energy is safely transferred and dissipated through the electromagnetic coupling of transformer T1.

[0076] Thus, the fast response characteristics of the transient diode ensure that the back EMF can be guided to a safe release path in the shortest possible time, without causing destructive voltage accumulation inside the switching unit. At the same time, the energy transfer mechanism at the secondary end of transformer T1 avoids the problem of the back EMF directly impacting the reference ground or power system in traditional solutions, significantly improving the reliability and service life of the entire drive system.

[0077] Continue reading Figure 2 In this embodiment, the first switching unit 210 includes a first switching transistor Q1. The drain of the first switching transistor Q1 is electrically connected to the motor through the first connection terminal A3, and the source is electrically connected to the first release terminal A1.

[0078] The second switching unit 220 includes a second switching transistor Q2. The drain of the second switching transistor Q2 is electrically connected to the motor through a third connection terminal A5, and the source is electrically connected to a second release terminal A2.

[0079] In this embodiment, the specific structures of the first switching unit 210 and the second switching unit 220 are further clarified. The first switching unit 210 includes a first switching transistor Q1, the drain of which is electrically connected to the single-phase AC permanent magnet synchronous motor through a first connection terminal A3, and the source of which is electrically connected to a first release terminal A1. The second switching unit 220 includes a second switching transistor Q2, the drain of which is electrically connected to the motor through a third connection terminal A5, and the source of which is electrically connected to a second release terminal A2. The first switching transistor Q1 and the second switching transistor Q2 are preferably N-type MOSFETs, which have advantages such as low on-resistance, fast switching speed, and low drive power, and can meet the drive control requirements of the single-phase AC permanent magnet synchronous motor.

[0080] During normal operation of the motor, transformer T1 provides power to the drive module 200 through the first power supply unit 110 and the second power supply unit 120 during the positive and negative half-cycles, respectively. During the negative half-cycle, the current path is opposite to that of the positive half-cycle. The second power supply unit 120 provides drive power, and the current direction changes accordingly. However, the effective drive of the motor is still achieved through the coordinated control of the first switch Q1 and the second switch Q2. By controlling the conduction timing and duty cycle of the first switch Q1 and the second switch Q2, the speed and torque output of the motor can be precisely adjusted.

[0081] When the motor stops running, it generates a back electromotive force (EMF) due to rotor inertia. The back EMF handling mechanism of this invention demonstrates its technical advantages: the generated back EMF can be quickly released through the first transient diode TVS1 via the second connection terminal A4 (i.e., the first release terminal A1) to the primary terminal T1A of transformer T1; simultaneously, the back EMF can also be released through the rapid response of the second transient diode TVS2 via the fourth connection terminal A6 (i.e., the second release terminal A2) to the secondary terminal T1B of transformer T1. Because the first power supply unit 110 and the second power supply unit 120 are connected to the primary terminal T1A and the secondary terminal T1B of transformer T1 respectively using a cross-connection method, this unique connection method allows transformer T1 to effectively absorb the energy of the back EMF based on the electromagnetic characteristics of the positive and negative half-cycles.

[0082] Specifically, when the back electromotive force (EMF) is conducted to the secondary winding of transformer T1 through the release terminal, the electromagnetic coupling of transformer T1 transfers this energy to the primary side, where it is eventually dissipated into the power grid. This energy transfer process is gradual, avoiding the impact of instantaneous large currents on the drive circuit. Simultaneously, since the primary terminal T1A and the secondary terminal T1B serve as mutual reference grounds in different half-cycles, the back EMF can selectively form an energy release loop through either the primary terminal T1A or the secondary terminal T1B, depending on its polarity and amplitude, thus achieving bidirectional safe release of the back EMF.

[0083] Through this innovative circuit topology and control method, this embodiment successfully achieves the technical goal of absorbing or transferring back EMF energy through transformer T1, effectively avoiding potential interference or damage to the reference ground circuit by back EMF, significantly improving the stability and reliability of the single-phase AC permanent magnet synchronous motor control system, and providing a strong guarantee for the long-term stable operation of the motor.

[0084] See Figure 3 In this embodiment, the first power supply unit 110 includes a first voltage regulator U1, which includes a third input terminal B3, a first output terminal F1 and a first common terminal. The third input terminal B3 is electrically connected to the first stage terminal T1A, the first output terminal F1 is electrically connected to the first input terminal B1, and the first common terminal is electrically connected to the second stage terminal T1B.

[0085] In this embodiment, the first voltage regulator U1 can be implemented using a voltage regulator chip, such as the CJ78L09 three-terminal regulator. This chip features a wide input voltage range, high voltage regulation accuracy, and overcurrent protection, and can convert the AC voltage of the secondary winding of transformer T1 into a stable DC power supply. Other types of voltage regulator chips can also be used, such as linear regulators like the LM7809 and AMS1117, or switching regulators like the LM2596, to achieve higher conversion efficiency. Furthermore, the first voltage regulator U1 can also be built using discrete components, such as a series voltage regulator circuit composed of Zener diodes, operational amplifiers, and power transistors, or a switching voltage regulator circuit composed of a PWM controller, switching transistors, and passive components such as inductors and capacitors.

[0086] In this embodiment, the first voltage regulator U1 has a dual function: on the one hand, it acts as a conventional power converter, and on the other hand, it plays an important role in processing back electromotive force (EMF) energy. The first voltage regulator U1 is mainly used to absorb the back EMF energy released to transformer T1 and convert it into usable operating power, thereby achieving effective consumption and utilization of back EMF energy. This design not only solves the problem of safe release of back EMF but also realizes energy recovery and utilization, improving the overall system's energy efficiency ratio.

[0087] Specifically, during the normal power supply phase, the first voltage regulator U1 obtains AC power from the primary stage T1A of transformer T1 through the third input terminal B3. After rectification, filtering, and voltage regulation, it provides a stable DC drive power to the drive module 200 through the first output terminal F1. During the release phase when the motor stops running and generates back EMF, when the back EMF is conducted to the primary stage T1A of transformer T1 through the first release terminal A1, the first voltage regulator U1 also obtains this portion of the back EMF energy released to transformer T1 through the third input terminal B3. Due to the energy absorption characteristics of the rectification and filtering circuits inside the voltage regulator, the energy of the back EMF is absorbed by the input stage circuit of the voltage regulator and dissipated as heat through the power consumption of the voltage regulator, or converted into working power at the output terminal to continue supplying the system.

[0088] The voltage regulator's circuit characteristics enable soft absorption of back EMF, avoiding the circuit shocks that may result from hard switching or simple resistor consumption. At the same time, the voltage regulator's voltage regulation characteristics ensure that the output power remains stable during the release of back EMF, without interfering with other parts of the drive system, thus achieving safe handling of back EMF and continuous and stable system operation.

[0089] Continue reading Figure 3 In this embodiment, the first power supply unit 110 further includes a first half-wave rectifier D1, and the first stage terminal T1A is electrically connected to the third input terminal B3 through the first half-wave rectifier D1.

[0090] In this embodiment, the first half-wave rectifier D1 is implemented using a single rectifier diode, which can be a Schottky diode, a fast recovery diode, or a common silicon diode. Schottky diodes have the advantages of low forward voltage drop and fast switching speed, making them suitable for low-voltage, high-current applications; fast recovery diodes have a short reverse recovery time, making them suitable for high-frequency rectification applications; and common silicon diodes are inexpensive and suitable for general rectification needs. The main function of the half-wave rectifier is to unidirectionally conduct the AC voltage output from the primary terminal T1A of transformer T1, allowing only the current during the positive half-cycle to pass through, thereby providing a pulsating DC voltage to the subsequent first voltage regulator U1.

[0091] Under normal operating conditions, when the primary terminal T1A of transformer T1 outputs a positive half-cycle voltage, the first half-wave rectifier D1 conducts, allowing current to flow and supplying power to the third input terminal B3 of the first voltage regulator U1. When the negative half-cycle voltage is output, the rectifier diodes are cut off, blocking reverse current. Although this half-wave rectification method only utilizes half of the AC voltage cycle, it has a simple structure and low cost, making it sufficient for the drive control of single-phase AC permanent magnet synchronous motors.

[0092] The first half-wave rectifier D1 plays a crucial role in handling back EMF. When the motor stops running and generates back EMF, and this back EMF is conducted to the primary terminal T1A of transformer T1 through the first release terminal A1, the first half-wave rectifier D1 can perform directional screening and processing of the back EMF. Due to the randomness of the polarity and amplitude of the back EMF, the first half-wave rectifier D1, through its unidirectional conduction characteristic, only allows the back EMF component that meets the forward conduction conditions to pass through, guiding it to the first voltage regulator U1 for energy absorption and conversion. This ensures that the back EMF energy can be conducted in an orderly manner to the voltage regulator for safe processing, avoiding potential impacts of reverse current on the circuit.

[0093] Continue reading Figure 3 In this embodiment, the second power supply unit 120 includes a second voltage regulator U2, which includes a fourth input terminal B4, a second output terminal F2, and a second common terminal. The second input terminal B2 is electrically connected to the second stage terminal T1B, the second output terminal F2 is electrically connected to the second input terminal B2, and the second common terminal is electrically connected to the first stage terminal T1A.

[0094] The second power supply unit 120 also includes a second half-wave rectifier D2, and the second stage terminal T1B is electrically connected to the fourth input terminal B4 via the second half-wave rectifier D2.

[0095] In this embodiment, the structure and function of the second voltage regulator U2 are similar to those of the first voltage regulator U1. It can also be implemented using three-terminal voltage regulator chips such as CJ78L09 and LM7809, or using a switching regulator or a voltage regulator circuit built with discrete components. The second half-wave rectifier D2 also uses a single rectifier diode, which can be a Schottky diode, a fast recovery diode, or a common silicon diode.

[0096] By setting up two independent voltage regulation units, the first voltage regulator U1 and the second voltage regulator U2, this embodiment achieves a true dual-power supply architecture. The two voltage regulators are cross-connected: the third input terminal B3 of the first voltage regulator U1 is connected to the first stage terminal T1A, and the first common terminal is connected to the second stage terminal T1B; the fourth input terminal B4 of the second voltage regulator U2 is connected to the second stage terminal T1B, and the second common terminal is connected to the first stage terminal T1A. This cross-connection allows the two voltage regulators to work alternately and serve as mutual reference grounds during different half-cycles of the AC power supply.

[0097] During the positive half-cycle, the first regulator U1 draws power from the primary stage terminal T1A through the first half-wave rectifier D1, while the secondary stage terminal T1B serves as the reference ground for the first regulator U1. During the negative half-cycle, the second regulator U2 draws power from the secondary stage terminal T1B through the second half-wave rectifier D2, while the primary stage terminal T1A serves as the reference ground for the second regulator U2. This operating mode not only fully utilizes the positive and negative half-cycles of the AC power supply but also ensures that the drive module 200 receives a continuous and stable operating power supply.

[0098] In handling back electromotive force (EMF), the two voltage regulators also play a crucial role. When the back EMF is conducted to the first stage terminal T1A and the second stage terminal T1B through the first release terminal A1 and the second release terminal A2, respectively, the first voltage regulator U1 and the second voltage regulator U2 can absorb and process the back EMF energy conducted to their respective input terminals according to the polarity and conduction path of the back EMF. Through the directional filtering of the two half-wave rectifiers and the energy conversion of the two voltage regulators, the energy of the back EMF is handled more comprehensively and effectively, further improving the system's ability to handle back EMF and its overall operational stability.

[0099] The dual voltage regulator configuration not only achieves efficient utilization of AC power and stable DC output, but also provides a reliable energy absorption channel for the bidirectional safe release of back EMF through the cross-connection design, ensuring the long-term stable operation of the single-phase AC permanent magnet synchronous motor control system.

[0100] See Figure 1 and Figure 4 In this embodiment, the system also includes a main control module 300, which includes a detection terminal ZDC. The control circuit of the single-phase AC permanent magnet synchronous motor also includes a zero-point detection module 400, which includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is electrically connected to the primary terminal T1A, and the other end of the first resistor R1 is grounded through the second resistor R2. The detection terminal ZDC is electrically connected to the other end of the first resistor R1.

[0101] In this embodiment, the zero-point detection module 400 plays a crucial role in signal detection and control. It is mainly used to detect the zero-point transition moment of the secondary voltage of transformer T1 and transmit the corresponding detection signal to the main control module 300. This module forms a voltage divider circuit using a first resistor R1 and a second resistor R2 to divide the voltage at the primary terminal T1A of transformer T1, converting the high-voltage signal into a low-voltage detection signal suitable for the input requirements of the main control chip. The selection of the resistance values ​​of the first resistor R1 and the second resistor R2 needs to comprehensively consider factors such as the voltage division ratio, input impedance matching, and power consumption control. Typically, a larger resistance value is chosen for the first resistor R1 to limit the current, while a smaller resistance value is chosen for the second resistor R2 to obtain a suitable detection voltage.

[0102] The core function of the zero-point detection module 400 is to provide a precise timing reference for the commutation control of a single-phase AC permanent magnet synchronous motor. Based on the principle of electromagnetic induction, the operation of a single-phase AC permanent magnet synchronous motor requires precise commutation control according to the rotor position and power supply phase to ensure that the stator magnetic field and the rotor magnetic field maintain the optimal phase relationship, thereby obtaining the maximum electromagnetic torque output. Since the voltage and current of the single-phase AC power supply periodically cross zero points, these zero-point moments are the ideal time for commutation control.

[0103] Specifically, when the voltage at the primary terminal T1A of transformer T1 crosses zero, the zero-point detection module 400 generates a corresponding voltage change, which is transmitted to the main control module 300 via the detection terminal ZDC. Upon receiving the zero-point detection signal, the main control module 300 precisely controls the on / off timing of the first switch Q1 and the second switch Q2 according to a preset control algorithm and the current operating state of the motor, thereby achieving timely switching of the power supply to the motor windings. This commutation control method based on zero-point detection ensures the continuity of the power supply to the windings and the accuracy of the phase during motor rotation.

[0104] Because the normal operation of a single-phase AC permanent magnet synchronous motor requires constant switching of the power supply direction and timing of the windings to maintain continuous rotor rotation, the main control module 300 can perform commutation operations at the optimal time through the precise timing signal provided by the zero-point detection module 400. This avoids problems such as torque fluctuations, efficiency reduction, or loss of synchronization that may result from blind commutation. Simultaneously, the zero-point detection signal can also be used for motor start-up control, speed detection, and fault protection functions, providing crucial feedback information for the entire control system and significantly improving the accuracy and reliability of single-phase AC permanent magnet synchronous motor control.

[0105] See Figure 5 The present invention further proposes a control method for a unidirectional AC motor. This control method is applied to the control circuit of the single-phase AC permanent magnet synchronous motor described in the preceding embodiments. The unidirectional AC motor control method includes:

[0106] S10. Determine the positive and negative half-cycles of the alternating current;

[0107] S20. Obtain the initial position of the motor rotor;

[0108] S30. Based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC power, supply power to the motor during the positive or negative half-cycle of the AC power.

[0109] S40, Real-time monitoring of the zero-crossing position of AC power;

[0110] S50. Disconnect the motor power supply within a preset time before the zero-crossing position.

[0111] In step S10, the determination of the positive and negative half-cycles of the AC current is achieved through the zero-point detection module 400. The zero-point detection module 400 monitors the voltage change at the primary terminal T1A of transformer T1. When the voltage changes from a positive value to a negative value or vice versa, it indicates a half-cycle switch. The main control module 300 determines in real time whether the AC current is in the positive or negative half-cycle based on the signal received from the detection terminal ZDC. Assuming the magnetic pole polarity applied to the motor stator during the positive half-cycle is S pole and the magnetic pole polarity applied during the negative half-cycle is N pole, this polarity setting provides a reference for subsequent commutation control.

[0112] Step S20 obtains the initial position of the motor rotor using a linear Hall sensor. The linear Hall sensor is installed near the motor stator and can detect changes in the magnetic field strength and polarity of the rotor's permanent magnets. When the rotor's N pole approaches the Hall sensor, the sensor outputs a high-level signal; when the rotor's S pole approaches, the sensor outputs a low-level signal. The main control module 300 accurately determines the current magnetic pole position and angle information of the rotor by reading the output signal of the Hall sensor.

[0113] Step S30 is the core of the entire control method. Based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC current, it determines whether to supply power to the motor during the positive or negative half-cycle of the AC current. Its essence is based on the interaction principle of electromagnetic induction and the magnetic field of a permanent magnet. When single-phase AC current is applied to the stator windings, it generates an alternating magnetomotive force, which interacts with the magnetic field of the permanent magnet on the rotor, generating an electromagnetic torque that drives the motor to rotate. Utilizing the basic magnetic principle of "like poles repel, unlike poles attract," the program controls whether to energize the motor during the positive or negative half-cycle of the AC current, thereby precisely controlling the initial rotation direction of the motor. For example, when the Hall sensor detects that the rotor's N pole is approaching, if the motor is to rotate clockwise, it should be energized during the negative half-cycle of the AC current. At this time, the stator generates an N-pole magnetic field, which repels the rotor's N pole, driving the rotor to rotate; conversely, if counterclockwise rotation is desired, it should be energized during the positive half-cycle.

[0114] Step S40 involves real-time monitoring of the AC voltage's zero-crossing position, a crucial step in ensuring synchronized motor operation. The zero-crossing detection module 400 continuously monitors changes in the AC voltage, and when the voltage approaches zero, it sends a zero-crossing detection signal to the main control module 300. The main control module 300 uses this signal to accurately determine the AC voltage's phase information.

[0115] Step S50 disconnects the motor power supply within a preset time before the zero-crossing point. This preset time is typically set to t milliseconds, where t = 1 / 10T, and T is the half-cycle time of the AC current. This early disconnection control strategy is to avoid supplying power to the motor at the instant the voltage crosses zero, preventing unstable magnetic fields and torque fluctuations. After the motor starts rotating, the motor power supply is turned off t milliseconds before the AC current crosses zero, and then the motor is allowed to rotate to the predetermined N or S position (determined by the Hall signal value) before the motor power supply is turned on again.

[0116] Once the motor reaches a stable operating state, the Hall sensor signal and the switch control signal will operate at the same frequency as the AC power supply, and will only be turned off at the zero-crossing point by t milliseconds. This control method achieves perfect synchronization between the motor and the power grid, ensuring the efficient and stable operation of the single-phase AC permanent magnet synchronous motor. The entire commutation process, through precise timing control and position feedback, achieves orderly switching of the motor's magnetic field, ensuring that the rotor can rotate synchronously with the stator magnetic field, avoiding problems such as loss of step and torque pulsation.

[0117] See Figure 6 In this embodiment, the step of supplying power to the motor during the positive or negative half-cycle of the AC current, based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC current, includes:

[0118] S31. If the rotor position lags behind the AC phase, disconnect the motor power supply and wait for the rotor to rotate to the correct position before reconnecting the power.

[0119] S32. If the rotor position is ahead of the AC phase, delay the motor power-on until the phase is matched and then power on again.

[0120] In this embodiment, based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC power, the step of supplying power to the motor during the positive or negative half-cycle of the AC power is further refined into two specific phase adjustment strategies to achieve precise matching between the rotor position and the AC power phase.

[0121] Step S31 addresses the issue of the rotor position lagging behind the AC current phase. When the main control module 300 detects through the Hall sensor that the actual magnetic pole position of the rotor lags behind the ideal position corresponding to the current AC current phase, the system immediately disconnects the motor power supply, stopping the power supply to the stator windings. At this time, the rotor will continue to rotate due to inertia, gradually approaching the ideal phase position. The main control module 300 continuously monitors the output signal of the Hall sensor, tracking the rotor's position changes in real time. When it detects that the rotor has rotated to the correct position matching the current AC current phase, the main control module 300 will re-control the switching unit to conduct, restoring the power supply to the motor. This power-off, waiting, and power-back control strategy effectively corrects the rotor position lag problem, ensuring that the rotor and stator magnetic field remain synchronized.

[0122] Step S32 handles the case where the rotor position is ahead of the AC phase. When the Hall sensor detects that the rotor's magnetic pole position is ahead of the ideal position corresponding to the AC phase, the main control module 300 adopts a delayed power-on strategy. At this time, the main control module 300 does not immediately supply power to the motor, but continuously monitors the phase change of the AC and the rotor's position state, calculating the delay time required for phase matching. During this delay period, the motor is in a de-energized state, and the rotor speed gradually decreases due to the lack of driving torque, with the relative phase adjusting accordingly. When the main control module 300 determines that the rotor position and AC phase are about to reach a matching state, it promptly controls the switching unit to conduct, re-energizing the motor. This delayed power-on strategy effectively solves the problem of rotor position being ahead, achieving precise phase alignment.

[0123] The core of these two phase adjustment strategies lies in achieving phase synchronization between the rotor and the AC power supply through dynamic power control. Whether lagging or leading, the system can adjust the rotor position to an ideal state that matches the AC power phase through appropriate power-off or delayed power-on operations. This precise phase matching control ensures that the motor can maintain synchronous operation under any operating conditions, avoiding problems such as torque fluctuations, efficiency reduction, or loss of synchronization caused by phase mismatch.

[0124] By implementing this refined phase adjustment control, the single-phase AC permanent magnet synchronous motor can maintain good synchronization performance under various starting conditions and operating states, significantly improving the stability and reliability of motor operation and providing a strong guarantee for the efficient operation of the motor.

[0125] See Figure 7 In this embodiment, the control method for a unidirectional AC motor further includes:

[0126] S60. Real-time monitoring of motor speed to determine whether the motor rotor position signal is synchronized with the switching time of the positive and negative half-cycles of AC power.

[0127] S70. If the rotor position signal is detected to be out of sync with the AC half-cycle switching, disconnect the motor power supply and wait until the start of the next AC half-cycle to re-evaluate the synchronization status before powering on.

[0128] In this embodiment, step S60 monitors the motor speed in real time and determines whether the motor rotor position signal is synchronized with the switching time of the positive and negative half-cycles of the AC power. The main control module 300 continuously acquires rotor position information through a Hall sensor, and simultaneously monitors the half-cycle switching time of the AC power in real time through the zero-point detection module 400. The two signals are compared and analyzed to determine whether the actual rotation frequency of the rotor is consistent with the frequency of the AC power. Under ideal synchronous operation, the signal change of the Hall sensor should be strictly synchronized with the half-cycle switching of the AC power.

[0129] Step S70 corrects the detected asynchrony. If the rotor position signal is found to be out of sync with the AC half-cycle switching, the system immediately disconnects the motor power supply, stops supplying power to the stator windings, and then waits until the start of the next AC half-cycle to reassess the synchronization status before resuming power.

[0130] When the motor is running under load, or encounters adverse factors such as external interference or power grid voltage fluctuations, the motor speed may fluctuate, becoming faster or slower. In this situation, the Hall sensor signal and the commutation timing of the positive and negative half-cycles of the AC power supply cannot maintain synchronization, disrupting the system's synchronous operation. To ensure that each time the motor is powered on, it generates torque in the same direction, avoiding speed reduction or loss of synchronization caused by reverse torque, the system must immediately shut down the motor power supply upon detecting asynchrony and wait for a suitable time to restart it.

[0131] Specifically, when the motor speed slows down, for example, during the negative half-cycle of the AC power supply (T-2T period), if the motor rotor has not yet rotated to the predetermined position near the Hall sensor at the S pole, the system will immediately shut off the motor power to avoid generating reverse torque due to powering on the wrong rotor position. The system waits for the motor to continue rotating due to inertia until the rotor rotates below the N0 position (i.e., during the rotation from the N pole to the S pole), at which point the motor is powered on again, strictly adhering to the control rule of shutting off power t milliseconds before the AC power crosses zero.

[0132] When the motor speed increases, the situation is similar but the handling method is reversed. For example, when the second positive half-cycle of the AC power (the 2T-3T period) arrives, if the motor rotor has already rotated to the N pole and is close to the Hall sensor position, the system cannot immediately start the motor. Instead, it must wait for the motor to continue rotating due to inertia until the rotor rotates to a position higher than N0 (i.e., during the rotation from the S pole to the N pole) before restarting the motor power supply. This also follows the timing control of shutting off the power supply t milliseconds before the AC power crosses zero.

[0133] Thus, through this cyclical dynamic adjustment mechanism, the system determines whether the rotor position of the motor is consistent with the torque direction of the currently set rotation direction in each AC half-cycle. This real-time monitoring and dynamic correction control strategy ensures that the motor maintains a stable synchronous operation under various operating conditions, effectively responding to the impact of load changes and external disturbances on the motor's operational stability, and guaranteeing the high reliability and strong adaptability of the single-phase AC permanent magnet synchronous motor control system.

[0134] The above description is only a part or preferred embodiment of the invention. Neither the text nor the drawings should limit the scope of protection of the invention. All equivalent structural transformations made using the contents of the invention specification and drawings under the overall concept of the invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the invention.

Claims

1. A control circuit for a single-phase AC permanent magnet synchronous motor, characterized in that, include: A power supply module, comprising a transformer, a first power supply unit, and a second power supply unit, wherein the transformer comprises a primary terminal and a secondary terminal, and the first power supply unit and the second power supply unit are both electrically connected to the primary terminal and the secondary terminal; The drive module includes a first release terminal, a second release terminal, a first input terminal, and a second input terminal. The first input terminal is electrically connected to the first power supply unit, and the second input terminal is electrically connected to the second power supply unit. The first release terminal and the second release terminal are respectively electrically connected to the first stage terminal and the second stage terminal. The first release terminal and the second release terminal are used to release back electromotive force. The first power supply unit includes a first voltage regulator, which includes a third input terminal, a first output terminal, and a first common terminal. The third input terminal is electrically connected to the first stage terminal, the first output terminal is electrically connected to the first input terminal, and the first common terminal is electrically connected to the second stage terminal. The second power supply unit includes a second voltage regulator, which includes a fourth input terminal, a second output terminal, and a second common terminal. The second input terminal is electrically connected to the second stage terminal, the second output terminal is electrically connected to the second input terminal, and the second common terminal is electrically connected to the first stage terminal.

2. The control circuit for a single-phase AC permanent magnet synchronous motor according to claim 1, characterized in that, The driver module also includes: A first switching unit, the first switching unit includes a first connection terminal and a second connection terminal, the first connection terminal is used to electrically connect to the motor, and the second connection terminal is the first release terminal; The second switching unit includes a third connection terminal and a fourth connection terminal. The third connection terminal is electrically connected to the motor, and the fourth connection terminal is the second release terminal. A first transient diode is electrically connected between the motor and the second connection terminal; The second transient diode is electrically connected between the motor and the fourth connection terminal.

3. The control circuit for a single-phase AC permanent magnet synchronous motor according to claim 2, characterized in that, The first switching unit includes a first switching transistor, the drain of the first switching transistor is electrically connected to the motor through the first connection terminal, and the source is electrically connected to the first release terminal; The second switching unit includes a second switching transistor, the drain of which is electrically connected to the motor through the third connection terminal, and the source of which is electrically connected to the second release terminal.

4. The control circuit for a single-phase AC permanent magnet synchronous motor according to claim 3, characterized in that, The first power supply unit further includes a first half-wave rectifier, and the first stage terminal is electrically connected to the third input terminal via the first half-wave rectifier.

5. The control circuit for a single-phase AC permanent magnet synchronous motor according to claim 1, characterized in that, The second power supply unit also includes a second half-wave rectifier, and the second stage terminal is electrically connected to the fourth input terminal via the second half-wave rectifier.

6. The control circuit for a single-phase AC permanent magnet synchronous motor according to claim 1, characterized in that, It also includes a main control module, which includes a detection terminal; the control circuit of the single-phase AC permanent magnet synchronous motor also includes a zero-point detection module, which includes a first resistor and a second resistor. One end of the first resistor is electrically connected to the first stage terminal, and the other end of the first resistor is grounded after passing through the second resistor. The detection terminal is electrically connected to the other end of the first resistor.

7. A control method for a unidirectional AC motor, wherein the control method for the unidirectional AC motor is applied to the control circuit of the single-phase AC permanent magnet synchronous motor according to any one of claims 1 to 6, characterized in that, The control method for the unidirectional AC motor includes: Determine the positive and negative half-cycles of alternating current; Obtain the initial position of the motor rotor; Based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC power, the motor is powered during the positive or negative half-cycle of the AC power. Real-time monitoring of the zero-crossing position of the AC current; Disconnect the motor power supply within a preset time before the zero-crossing point.

8. The control method for a unidirectional AC motor according to claim 7, characterized in that, The step of supplying power to the motor during the positive or negative half-cycle of the AC current, based on the matching relationship between the initial position of the motor rotor and the positive and negative half-cycles of the AC current, includes: If the rotor position lags behind the AC phase, disconnect the motor power supply and wait for the rotor to rotate to the correct position before reconnecting the power. If the rotor position is ahead of the AC phase, the motor power-on is delayed until the phase is matched and then the motor is powered on again.

9. The control method for a unidirectional AC motor according to claim 8, characterized in that, Also includes: Real-time monitoring of motor speed to determine whether the motor rotor position signal is synchronized with the switching time of the positive and negative half-cycles of the AC power; If the rotor position signal is detected to be out of sync with the AC half-cycle switching, disconnect the motor power supply and wait until the start of the next AC half-cycle to reassess the synchronization status before powering on.

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