Back-to-back drive circuit and control device for single-phase ac permanent magnet synchronous motor

Abstract

The utility model discloses a kind of back-to-back drive circuit and control device for single-phase alternating current permanent magnet synchronous motor, the back-to-back drive circuit for single-phase alternating current permanent magnet synchronous motor includes switch module, switch module includes first switch unit and second switch unit, first switch unit includes first connecting end and second connecting end, second switch unit includes third connecting end and fourth connecting end, third connecting end is electrically connected motor, fourth connecting end is electrically connected, first transient diode is electrically connected between motor and second connecting end, main control module is electrically connected first switch unit and second switch unit respectively, main control module controls first switch unit, second switch unit works. When counter electromotive force exceeds the breakdown voltage of TVS tube, transient diode will reverse direction and release overvoltage energy to main circuit through second connecting end in second switch unit, so as to effectively protect transistor device in first switch unit and second switch unit.

Description

Technical Field

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

[0002] In power electronics applications involving alternating current (AC), such as motor drives, efficient and reliable switching circuits are crucial. They need to be able to handle bidirectional current and cope with the significant back electromotive force (EMF) generated by inductive loads during switching operations to ensure system stability and robustness.

[0003] The relevant technical solution employs an N-type metal-oxide-semiconductor (NMOS) field-effect transistor with a back-to-back topology. That is, the sources (S) of two identical NMOS transistors are connected to ground, and their drains (D) face each other, resembling two people standing back-to-back. The gates are connected to the drive circuit, and the switching control of the AC power is achieved by connecting the two MOS transistors in series, as shown in the figure below. During the positive half-cycle of the AC power, when the gate driver is turned on, the current path is as follows: the power supply (ACL) flows through the motor load, through one MOS transistor (Q2) to fully turn it on, and then returns to ACN through the body diode of the other MOS transistor (Q1).

[0004] However, this back-to-back NMOS topology has the following technical problems. During the positive half-cycle of the AC current, when both MOSFETs are turned off simultaneously, only Q2 is actually turned off due to the body diode. At this time, the extremely high back electromotive force generated by the motor coil due to the voltage-current formula u(t)=L di / dt (the motor coil is equivalent to an inductor, and when the inductor is de-energized, the current changes from the running current to zero. With the current flowing through the inductor remaining in the same direction, a voltage relative to the inductor's running voltage is generated, called the back electromotive force, and the magnitude of the back electromotive force is proportional to the rate of change of current di / dt) will be entirely applied to the drain (D) of Q2, causing Q2 to bear excessive voltage stress. This situation can easily cause overvoltage damage to the MOSFET, thereby reducing the reliability and lifespan of the entire switching circuit. Utility Model Content

[0005] The main purpose of this invention is to propose a novel switching drive circuit and control device for single-phase AC permanent magnet synchronous motors, aiming to solve the problem of overvoltage damage to MOSFETs caused by energy accumulation at the MOSFET.

[0006] To achieve the above objectives, this utility model proposes a back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor. This back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor includes: A switch module includes a first switch unit and a second switch unit. The first switch unit includes a first connection terminal and a second connection terminal. The first connection terminal is used to electrically connect to a motor, and the second connection terminal is used to electrically connect to a power supply phase line. The second switch 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 electrically connected to... A first transient diode is electrically connected between the motor and the second connection terminal; The main control module is electrically connected to the first switch unit and the second switch unit respectively, and controls the operation of the first switch unit and the second switch unit.

[0007] In some embodiments, the first switching unit further includes a first switching transistor, the drain of the first switching transistor being electrically connected to the motor through the first connection terminal, and the source being electrically connected to the power supply phase line through the second connection terminal; The second switching unit further includes a second switching transistor, the drain of which is electrically connected to the motor via the third connection terminal, and the source of which is electrically connected to the power supply neutral line via the fourth connection terminal; The anode of the first transient diode is electrically connected to the source of the first switching transistor, and the cathode of the first transient diode is electrically connected to the drain of the second switching transistor.

[0008] In some embodiments, the device further includes a second transient diode, the anode of which is electrically connected to the source of the second switching transistor, and the cathode of which is electrically connected to the drain of the second switching transistor.

[0009] In some embodiments, the first switching unit further includes: A first driver, the first driver including a first output terminal and a first control terminal, the first output terminal being electrically connected to the gate of the first switching transistor; The optocoupler includes a first pin, a second pin, a third pin, and a fourth pin. The first pin is electrically connected to the power supply, the second pin is electrically connected to the main control module, the third pin is electrically connected to the first control terminal, and the fourth pin is grounded.

[0010] In some embodiments, the second switching unit further includes a second driver, the second driver including a second output terminal and a second control terminal, the second output terminal being electrically connected to the gate of the second switching transistor, and the second control terminal being electrically connected to the main control module.

[0011] In some embodiments, the first switch and the second switch are N-channel MOSFETs.

[0012] In some embodiments, a third transient diode is further included, the third transient diode having a first terminal and a second terminal, the first terminal being used to electrically connect to the positive terminal of the motor, and the second terminal being used to electrically connect to the negative terminal of the motor.

[0013] In some embodiments, the device further includes an energy storage and absorption module, which includes a fifth connection terminal and a sixth connection terminal. The fifth connection terminal is electrically connected to the first terminal of the third transient diode, and the sixth connection terminal is electrically connected to the second terminal of the third transient diode.

[0014] In some embodiments, an electromagnetic interference suppression circuit is further included, which is connected in parallel across the two ends of the motor.

[0015] This invention further proposes a control device, including the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor as described in the foregoing embodiments.

[0016] The beneficial effects of this utility model are as follows: By setting a first transient diode between the second connection terminal and the motor, and placing the motor between the drains of the two MOSFETs (the drain being the terminal with the highest withstand voltage in the MOSFET), the problem of overvoltage damage to the switching module caused by the back electromotive force generated when the motor is de-energized is solved. When the two MOSFETs switch simultaneously, the inductive characteristics of the motor windings will generate a high back electromotive force when the motor is braking or suddenly de-energized. This back electromotive force will be applied simultaneously to the drains of the TVS diode and the MOSFET in the first and second switching units. When the back electromotive force exceeds the breakdown voltage of the TVS diode, the transient diode (i.e., the TVS diode) will conduct in reverse and release the overvoltage energy into the main circuit through the second connection terminal. In this way, through this energy transfer mechanism, the overvoltage energy can be prevented from accumulating at the switching transistor, thereby effectively protecting the transistor devices in the first and second switching units from overvoltage impact. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the module electrical connections of an embodiment of the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to the present invention. Figure 2 This is a circuit diagram of one embodiment of the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to the present invention.

[0018] Explanation of icon numbers: 100. Switch module; 110. First switching unit; A1. First connection terminal; A2. Second connection terminal; Q1. First switching transistor; U3, First driver; A5, First output terminal; A6, First control terminal; 120. Second switching unit; A3. Third connection terminal; A4. Fourth connection terminal; Q2. Second switching transistor; U4, second driver; A7, second output terminal; A8, second control terminal; TVS1, first transient diode; U1, Main Control Module; TVS2, second transient diode; U2, optocoupler; B1, first pin; B2, second pin; B4, third pin; B5, fourth pin; TVS3, third transient diode; A9, first terminal; A10, second terminal; 200. Energy storage and absorption module; 201. Fifth connection terminal; 202. Sixth connection terminal; 300. Electromagnetic interference suppression circuit.

[0019] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The solutions in the embodiments of this utility model 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 this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0021] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment 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 indicator will also change accordingly.

[0022] 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.

[0023] Furthermore, the use of terms such as "first" and "second" in this utility model 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 only on the basis of being achievable by those skilled in the art. When 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 this utility model.

[0024] Reference Figure 1 This utility model embodiment proposes a back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor, which includes: The switch module 100 includes a first switch unit 110 and a second switch unit 120. The first switch unit 110 includes a first connection terminal A1 and a second connection terminal A2. The first connection terminal A1 is used to electrically connect to the motor, and the second connection terminal A2 is used to electrically connect to the power supply phase line. The second switch unit 120 includes a third connection terminal A3 and a fourth connection terminal A4. The third connection terminal A3 is electrically connected to the motor, and the fourth connection terminal A4 is electrically connected to... The first transient diode TVS1 is electrically connected between the motor and the second connection terminal A2; The main control module U1 is electrically connected to the first switch unit 110 and the second switch unit 120 respectively, and the main control module U1 controls the operation of the first switch unit 110 and the second switch unit 120.

[0025] In this embodiment, the switching module 100 includes a first switching unit 110 and a second switching unit 120. The main function of the two switching units is to control the power supply to the motor, forming a complete current loop. The first switching unit 110 includes a first connection terminal A1 and a second connection terminal A2, wherein the first connection terminal A1 is electrically connected to one end of the motor, and the second connection terminal A2 is electrically connected to the phase line terminal of the power supply (such as ACL), for providing a power path. The second switching unit 120 includes a third connection terminal A3 and a fourth connection terminal A4, wherein the third connection terminal A3 is electrically connected to the other end of the motor, and the fourth connection terminal A4 is electrically connected to the neutral line terminal of the power supply (such as ACN), forming a closed loop. Both the first switching unit 110 and the second switching unit 120 can be implemented using power switching devices such as MOSFETs, IGBTs, and BJTs. MOSFETs are preferred because they have the advantages of fast switching speed and low on-resistance.

[0026] The first transient diode TVS1 (TVS1) is electrically connected between the motor and the second connection terminal A2. In this embodiment, its main function is to release the high-voltage reverse electromotive force generated by the motor load onto ACL and ACN, thereby preventing the burnout of critical components such as the MOSFET. The first transient diode TVS1 can be a TVS diode, a Zener diode, or other protection devices with voltage clamping function.

[0027] The main control module U1 is mainly responsible for controlling the working state of the first switching unit 110 and the second switching unit 120. It can be implemented using microcontrollers, DSPs, FPGAs and other control devices. The switching units are adjusted by PWM signals or switching control signals.

[0028] Under normal operating conditions, the main control module U1 simultaneously controls the first switching unit 110 and the second switching unit 120 to turn on or off according to the control strategy, providing AC power to the single-phase AC permanent magnet synchronous motor and enabling the motor to operate normally. When the main control module U1 controls the first switching unit 110 and the second switching unit 120 to turn off, the motor stops running. Due to the principle of electromagnetic induction, the magnetic field energy in the motor windings cannot disappear instantaneously. According to Lenz's law, the changing magnetic flux will generate a back electromotive force in the windings. The direction of this back electromotive force is opposite to the direction of the original current, attempting to maintain the original magnetic field state.

[0029] At this time, a reverse electromotive force is applied to the first switching unit 110 and the second switching unit 120. When the voltage amplitude exceeds the breakdown threshold voltage of the first transient diode TVS1, the first transient diode TVS1 breaks down and conducts in the reverse direction, releasing the energy of the reverse electromotive force through the conduction path. The specific energy release path is: motor winding, first transient diode TVS1, second connection terminal A2, ACL or ACN. In this way, the overvoltage energy is transferred to the main circuit, avoiding the accumulation of energy at the switching devices and causing damage.

[0030] The beneficial effects of this utility model are as follows: By setting a first transient diode (TVS1) between the second connection terminal A2 and the motor, and placing the motor between the two switching units, the overvoltage damage to the switching module 100 caused by the back electromotive force generated when the motor is de-energized is effectively solved. When the motor is braking or suddenly de-energized, the inductive characteristics of the motor windings will generate a high back electromotive force, which will be applied simultaneously to the protection devices and switching transistors in the first switching unit 110 and the second switching unit 120. When the back electromotive force exceeds the breakdown voltage of the transient diode, the transient diode quickly reverses its conduction, releasing the overvoltage energy into the main circuit through the second connection terminal A2, thus achieving orderly energy transfer. This protection mechanism avoids the accumulation of overvoltage energy at the switching transistor, thereby effectively protecting the power devices in the first switching unit 110 and the second switching unit 120 from overvoltage impact, improving the reliability and service life of the drive circuit, and reducing the risk of device damage and maintenance costs.

[0031] See Figure 2 In this embodiment, the first switching unit 110 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 A1, and the source is electrically connected to the power supply phase line terminal. The second switching unit 120 includes a second switching transistor Q2. The drain of the second switching transistor Q2 is electrically connected to the motor through the third connection terminal A3, and the source is electrically connected to the neutral line terminal of the power supply. The anode of the first transient diode TVS1 is electrically connected to the source of the first switching transistor Q1, and the cathode of the first transient diode TVS1 is electrically connected to the drain of the second switching transistor Q2.

[0032] In this embodiment, the first switching unit 110 includes a first switching transistor Q1, preferably an N-type MOSFET (NMOS). Its drain is electrically connected to one end of the motor via a first connection terminal A1, and its source is electrically connected to the power supply phase line terminal (ACL). NMOS transistors have advantages such as low on-resistance, fast switching speed, and simple driving. As the terminal with the highest withstand voltage in a MOSFET, its drain can withstand high voltage surges. The first switching transistor Q1 can also be replaced by a P-type MOSFET, an IGBT, or other power switching devices.

[0033] The second switching unit 120 includes a second switching transistor Q2, which is also preferably an N-type MOSFET. Its drain is electrically connected to the other end of the motor through the third connection terminal A3, and its source is electrically connected to the power supply neutral line terminal (ACN). It forms a back-to-back driving configuration with the first switching transistor Q1. The two switching transistors work together to provide AC power to the motor.

[0034] The anode of the first transient diode TVS1 is connected to the source of the first switching transistor Q1, and the cathode is connected to the drain of the second switching transistor Q2, forming a protective path between the two switching transistors. The first transient diode TVS1 can be a TVS diode, Zener diode, or other device with bidirectional clamping function. When the voltage across its terminals exceeds its breakdown voltage, it can quickly conduct, providing a low-impedance discharge path.

[0035] Under normal operating conditions, the main control module U1 alternately controls the switching on and off of the first switch Q1 and the second switch Q2 to provide AC power to the single-phase AC permanent magnet synchronous motor. When the main control module U1 controls both switches to turn off simultaneously, the motor stops running. However, due to the inductive characteristics of the motor windings, the energy stored in the magnetic field cannot disappear instantly. According to Faraday's law of electromagnetic induction, the change in magnetic flux will induce a back electromotive force in the windings. The polarity of this back electromotive force is opposite to the direction of the original operating current.

[0036] When the amplitude of the back electromotive force generated by the motor exceeds the breakdown voltage of the first transient diode TVS1, the first transient diode TVS1 quickly breaks down and conducts, providing a discharge path for the back electromotive force. The specific energy release path is: one end of the motor, the drain of the second switching transistor Q2, the cathode of the first transient diode TVS1, the anode of the first transient diode TVS1, the source of the first switching transistor Q1, and the power supply phase line terminal (ACL) or the power supply neutral line terminal (ACN). Simultaneously, energy at the other end of the motor is released through a corresponding path. Through this bidirectional protection mechanism, the energy of the back electromotive force is effectively transferred to the main power supply circuit, preventing accumulation at the switching transistors and thus avoiding device damage.

[0037] By connecting the anode of the first transient diode TVS1 to the source of the first switching transistor Q1 and the cathode to the drain of the second switching transistor Q2, a bidirectional protection network is formed between the two switching transistors. When the motor is de-energized, a reverse electromotive force is generated. This configuration provides a low-impedance path for overvoltage energy to be released directly from the motor through the first transient diode TVS1 to the ACL / ACN, effectively protecting both switching transistors from overvoltage surges. Since the drain of the MOSFET has the highest withstand voltage, connecting the motor to the drain terminal further enhances the system's overvoltage resistance. This back-to-back protection configuration not only simplifies the circuit structure but also provides reliable bidirectional overvoltage protection, ensuring the safe operation of the switching devices under various operating conditions, significantly improving the reliability and lifespan of the drive circuit, and reducing system maintenance costs.

[0038] Continue reading Figure 2 In this embodiment, a second transient diode TVS2 is also included. The anode of the second transient diode TVS2 is electrically connected to the source of the second switching transistor Q2, and the cathode of the second transient diode TVS2 is electrically connected to the drain of the second switching transistor Q2.

[0039] In this embodiment, two transient diodes are used for back electromotive force (EMF) release protection. Specifically, based on the previous embodiment, a second transient diode, TVS2, is added to form a symmetrical dual-path protection configuration. The first transient diode, TVS1, is correspondingly disposed across the first switching transistor Q1, and the second transient diode, TVS2, is correspondingly disposed across the second switching transistor Q2, to prevent uncontrollable damage that may be caused by back EMF being discharged through a random channel.

[0040] When the motor is de-energized and generates a back electromotive force (EMF), the two transient diodes provide independent protection paths for their respective corresponding switching transistors. The first transient diode, TVS1, protects the first switching transistor Q1. When the back EMF applied to Q1 exceeds the breakdown voltage of TVS1, TVS1 conducts, releasing the overvoltage energy to the power supply phase line. Similarly, the second transient diode, TVS2, protects the second switching transistor Q2. When the back EMF exceeds its breakdown threshold, TVS2 conducts, releasing the overvoltage energy to the power supply neutral line. The specific release path principle is the same as in the previous embodiment, but the dual transient diode configuration achieves a more reliable and symmetrical overvoltage protection mechanism, ensuring effective protection for both switching transistors and further improving the safety and reliability of the drive circuit.

[0041] Continue reading Figure 2 In this embodiment, the first switching unit 110 further includes: The first driver U3 includes a first output terminal A5 and a first control terminal A6. The first output terminal A5 is electrically connected to the gate of the first switching transistor Q1. Optocoupler U2 includes a first pin B1, a second pin B2, a third pin B4, and a fourth pin B5. The first pin B1 is electrically connected to the power supply, the second pin B2 is electrically connected to the main control module U1, the third pin B4 is electrically connected to the first control terminal A6, and the fourth pin B5 is grounded.

[0042] In this embodiment, the first driver U3 can be a driver chip, such as UCC27517DBVR, IR2110, TLP250, etc., mainly used to drive the first switching transistor Q1, providing sufficient drive current and voltage to ensure that the first switching transistor Q1 can be turned on and off quickly and reliably. To achieve better electrical isolation, an optocoupler U2 is used for isolation control. The first pin B1 is electrically connected to the power supply (VCC) to provide operating power to the optocoupler U2; the second pin B2 is electrically connected to the control signal output terminal of the main control module U1 to receive control commands issued by the main control module U1; the third pin B4 is electrically connected to the first control terminal A6 of the first driver U3 to transmit the isolated control signal to the first driver U3; and the fourth pin B5 is grounded (GND) to form a current loop.

[0043] Optocoupler U2 can also be replaced by an isolation module that can achieve the same function, as long as it can achieve electrical isolation between the first switching unit 110 and the second switching unit 120. Examples include isolation transformers, digital isolation chips (such as Si8422, ADUM1200, etc.), or magnetic coupling isolators. With this configuration, the main control module U1 can isolate and control the operating state of the first driver U3 by controlling the on and off states of optocoupler U2, achieving electrical isolation between the main control module U1 and the power switching section. This effectively prevents high-voltage interference from the power side from affecting the main control module U1, while protecting the safety of the main control module U1 and improving the reliability and anti-interference capability of the entire drive circuit.

[0044] Continue reading Figure 2 Furthermore, the second switching unit 120 also includes a second driver U4, which includes a second output terminal A7 and a second control terminal A8. The second output terminal A7 is electrically connected to the gate of the second switching transistor Q2, and the second control terminal is electrically connected to the main control module U1.

[0045] In this embodiment, the second driver U4 is similar to the first driver U3, also employing a MOS driver chip, such as a dedicated driver chip like the UCC27517DBVR or IR2110. Its main function is to provide sufficient driving capability for the second switch Q2. The second output terminal A7 of the second driver U4 is directly electrically connected to the gate of the second switch Q2, providing it with the driving voltage and current required for turn-on and turn-off. The second control terminal A8 is directly electrically connected to the main control module U1, receiving control signals from the main control module U1 to achieve precise control of the second switch Q2.

[0046] It should be noted that both the first driver U3 and the second driver U4 are MOS driver chips, but they can be replaced with discrete component gate drive circuits built from transistors or MOSFETs, or other driver circuits capable of quickly turning on and off the first and second switching transistors Q2. This flexible design option allows for the selection of a suitable driver scheme based on specific application requirements, cost considerations, and performance requirements, as long as reliable driving of the switching transistors can be ensured. By configuring dedicated drivers, the switching speed of the switching transistors can be improved, switching losses reduced, and better drive stability and reliability provided.

[0047] See Figure 2 In this embodiment, the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor further includes a third transient diode TVS3. The third transient diode TVS3 includes a first terminal A9 and a second terminal A10. The first terminal A9 is used to electrically connect to the positive terminal of the motor, and the second terminal A10 is used to electrically connect to the negative terminal of the motor.

[0048] In this embodiment, the third transient diode TVS3 is directly connected in parallel across the two ends of the motor, i.e., between the positive and negative terminals of the motor, forming direct protection for the motor end. The third transient diode TVS3 is preferably a bidirectional TVS diode, which has bidirectional clamping characteristics and can effectively suppress overvoltage in both positive and negative directions. When the reverse electromotive force generated when the motor is de-energized exceeds the breakdown voltage of the third transient diode TVS3, the third transient diode TVS3 immediately conducts bidirectionally, directly clamping and absorbing the overvoltage energy at the motor end, forming the first line of protection for the motor end.

[0049] By connecting bidirectional TVS diodes in parallel across the motor terminals, the safety of the drive circuit is further enhanced. This configuration implements multiple protection mechanisms: the third transient diode, TVS3, provides direct protection to the motor end, clamping the circuit at the first moment of back EMF generation; while the first transient diode, TVS1, and the second transient diode, TVS2, provide subsequent protection for the switching transistors. This triple transient diode protection system ensures that even in extreme cases where the motor generates extremely high back EMF, key components in the entire drive circuit can be effectively protected through multi-stage clamping and energy dissipation mechanisms, improving system reliability and safety margin, and reducing the risk of component damage.

[0050] See Figure 2 In this embodiment, the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor further includes an energy storage absorption module 200. The energy storage absorption module 200 includes a fifth connection terminal 201 and a sixth connection terminal 202. The fifth connection terminal 201 is electrically connected to the first terminal A9 of the third transient diode TVS3, and the sixth connection terminal 202 is electrically connected to the second terminal A10 of the third transient diode TVS3.

[0051] In this embodiment, the energy storage absorption module 200 is connected in parallel across the third transient diode TVS3. Its main function is to further absorb and buffer the reverse electromotive force energy generated when the motor is powered off. The energy storage absorption module 200 can adopt an RC absorption circuit, including a combination of resistors and capacitors (C5, C6, R4), which can convert transient energy into heat dissipation and buffer energy storage through capacitors. The first capacitor and the second capacitor in the energy storage absorption module 200 can be adjusted to a single capacitor according to actual application needs to simplify the circuit structure and reduce costs.

[0052] When the motor generates a back electromotive force (EMF), the energy storage absorption module 200 and the third transient diode TVS3 work together to form a dual protection mechanism. The third transient diode TVS3 provides fast clamping protection, limiting overvoltage to a safe range; the energy storage absorption module 200 further absorbs residual transient energy, smoothing out the energy impact of the back EMF through capacitor energy storage and resistor dissipation. It should be noted that if the amplitude of the motor's back EMF is small and insufficient to pose a threat to the system, this RC energy storage absorption circuit can be omitted to simplify the circuit design. This flexible configuration allows the drive circuit to be optimized for different power levels of motors and applications, achieving a reasonable balance between cost and complexity while ensuring safety.

[0053] See Figure 2 The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor also includes an electromagnetic interference suppression circuit 300, which is connected in parallel across the two ends of the motor.

[0054] In this embodiment, the electromagnetic interference suppression circuit 300 consists of a capacitor C19 and a resistor R20 connected in series and connected in parallel between the positive and negative terminals of the motor. This electromagnetic interference suppression circuit 300 is mainly used to suppress high-frequency electromagnetic interference signals generated during motor operation, preventing these interference signals from being conducted to other devices through the power line or causing electromagnetic interference to surrounding electronic equipment.

[0055] Capacitor C19, acting as a high-frequency bypass component, provides a low-impedance path for high-frequency interference signals, short-circuiting the high-frequency noise generated by the motor to ground or the power supply circuit. Resistor R20, connected in series with capacitor C19, acts as a damper, preventing oscillations caused by LC resonance and limiting the amplitude of transient current. By appropriately selecting the capacitance value of C19 and the resistance value of R20, electromagnetic interference in specific frequency bands can be effectively suppressed, improving the electromagnetic compatibility performance of the drive circuit. This simple yet effective EMI suppression configuration is not only cost-effective but also significantly reduces the electromagnetic radiation level of the system, ensuring that the drive circuit meets relevant electromagnetic compatibility standards and improving the overall system's stable operation in complex electromagnetic environments.

[0056] This utility model further proposes a control device, including the aforementioned back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor. The specific structure of this novel back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor is as described in the above embodiments. Since this control device adopts all the technical solutions of all the above embodiments, it possesses at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be elaborated upon here.

[0057] In this embodiment, the control device can be an integrated motor drive control system, incorporating the aforementioned novel back-to-back drive circuit as the core drive module. The control device may also include auxiliary components such as a housing, heat sink, terminals, and indicator lights, forming a complete product. The housing provides mechanical protection and electromagnetic shielding for the drive circuit; the heat sink dissipates heat generated by the switching devices during operation; the terminals connect to an external power source and the motor; and the indicator lights display the operating status.

[0058] This control device has complete motor drive functions and can be directly applied to various applications requiring single-phase AC permanent magnet synchronous motor drives, such as household appliances, industrial equipment, and automation devices. Its integrated design simplifies user operation and installation.

[0059] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. A back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor, characterized in that, include: A switch module includes a first switch unit and a second switch unit. The first switch unit includes a first connection terminal and a second connection terminal. The first connection terminal is used to electrically connect to a motor, and the second connection terminal is used to electrically connect to a power supply phase line. The second switch 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 electrically connected to... A first transient diode is electrically connected between the motor and the second connection terminal; The main control module is electrically connected to the first switch unit and the second switch unit respectively, and the main control module controls the operation of the first switch unit and the second switch unit.

2. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 1, characterized in that, The first switching unit further includes a first switching transistor, the drain of which is electrically connected to the motor through the first connection terminal, and the source of which is electrically connected to the power supply phase line through the second connection terminal; The second switching unit also includes a second switching transistor, the drain of which is electrically connected to the motor via the third connection terminal, and the source of which is electrically connected to the power supply neutral line via the fourth connection terminal; The anode of the first transient diode is electrically connected to the source of the first switching transistor, and the cathode of the first transient diode is electrically connected to the drain of the second switching transistor.

3. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 2, characterized in that, It also includes a second transient diode, the anode of which is electrically connected to the source of the second switching transistor, and the cathode of which is electrically connected to the drain of the second switching transistor.

4. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 2, characterized in that, The first switching unit further includes: A first driver, the first driver including a first output terminal and a first control terminal, the first output terminal being electrically connected to the gate of the first switching transistor; The optocoupler includes a first pin, a second pin, a third pin, and a fourth pin. The first pin is electrically connected to the power supply, the second pin is electrically connected to the main control module, the third pin is electrically connected to the first control terminal, and the fourth pin is grounded.

5. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 4, characterized in that, The second switching unit further includes a second driver, which includes a second output terminal and a second control terminal. The second output terminal is electrically connected to the gate of the second switching transistor, and the second control terminal is electrically connected to the main control module.

6. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 2, characterized in that, The first and second switching transistors are N-channel MOSFETs.

7. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 1, characterized in that, It also includes a third transient diode, which has a first end and a second end. The first end is used to electrically connect to the positive connection end of the motor, and the second end is used to electrically connect to the negative connection end of the motor.

8. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 7, characterized in that, It also includes an energy storage and absorption module, which includes a fifth connection terminal and a sixth connection terminal. The fifth connection terminal is electrically connected to the first terminal of the third transient diode, and the sixth connection terminal is electrically connected to the second terminal of the third transient diode.

9. The back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor according to claim 8, characterized in that, It also includes an electromagnetic interference suppression circuit, which is connected in parallel across the two ends of the motor.

10. A control device, characterized in that, Includes the back-to-back drive circuit for a single-phase AC permanent magnet synchronous motor as described in any one of claims 1 to 9.

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