Single-phase permanent magnet motor, control method, device and program product thereof

Abstract

This disclosure provides a single-phase permanent magnet motor and its control method, device, and program. The single-phase permanent magnet motor includes: a first winding and a second winding wound on stator teeth, an inverter, and several relays. The relays are used to connect the first winding to the grid voltage and the second winding to the inverter when the motor is connected to the grid in grid-connected mode, by setting it to a first switching combination state. In grid-connected operation of the single-phase permanent magnet motor, the second winding is powered by the inverter and subjected to closed-loop control. When the motor speed fluctuates, the second winding can actively generate electromagnetic torque to suppress speed fluctuations by controlling the current, eliminating motor speed oscillations and improving operational stability. Compared to a single-phase permanent magnet motor system under frequency conversion control, the system efficiency is significantly improved; compared to direct grid connection of the single-phase permanent magnet motor, the problems of grid-connected speed oscillation and divergence are solved, improving the stability of system operation.

Description

Technical Field

[0001] This disclosure relates to the field of motor technology, and in particular to a single-phase permanent magnet motor and its control method, equipment and program products. Background Technology

[0002] Due to their advantages such as simple structure, low cost, and high efficiency, single-phase permanent magnet motors are widely used in low-power household appliances. Currently, systems driven by single-phase permanent magnet motors typically employ frequency conversion control, where the grid voltage is supplied to the single-phase permanent magnet motor via a rectifier-inverter.

[0003] The losses in a single-phase motor system originate from motor losses and controller losses. Directly connecting a single-phase permanent magnet motor to the power grid at its operating frequency can eliminate controller losses, greatly improving system efficiency. However, single-phase permanent magnet motors lack squirrel cage bars and damping windings, resulting in low inherent damping. Consequently, they exhibit poor stability when directly connected to the power grid at its operating frequency, making them prone to oscillations, loss of synchronism, and eventual shutdown. Summary of the Invention

[0004] The technical problem to be solved by this disclosure is to overcome the above-mentioned defects in the prior art and to provide a single-phase permanent magnet motor and its control method, equipment and program products.

[0005] This disclosure solves the above-mentioned technical problems through the following technical solution:

[0006] This disclosure provides a single-phase permanent magnet motor, which includes: a first winding and a second winding wound on stator teeth, an inverter, and a plurality of relays;

[0007] The relay is used to connect the first winding to the grid voltage and connect the second winding to the inverter when the motor is in grid-connected state, by setting it to a first switch combination state.

[0008] Optionally, the relay is further configured to connect the first winding to the inverter for operation when the motor is disconnected from the grid by setting it to a second switch combination state, and to de-energize the second winding.

[0009] Optionally, the inverter includes four power switching transistors and diodes corresponding to each power switching transistor;

[0010] The source of each power switch is electrically connected to the anode of the corresponding diode, the drain of each power switch is electrically connected to the cathode of the corresponding diode, and the gate of each power switch is connected to an external control signal.

[0011] The four power switching transistors include the upper transistor of bridge arm A, the lower transistor of bridge arm A, the upper transistor of bridge arm B, and the lower transistor of bridge arm B;

[0012] The drain of the upper transistor in bridge arm A and the drain of the upper transistor in bridge arm B are both connected to the positive terminal of the DC bus voltage. The source of the upper transistor in bridge arm A is also electrically connected to the drain of the lower transistor in bridge arm A. The source of the upper transistor in bridge arm B is also electrically connected to the drain of the lower transistor in bridge arm B. The source of the lower transistor in bridge arm A and the source of the lower transistor in bridge arm B are both connected to the inverting terminal of the DC bus voltage.

[0013] Optionally, when the inverter adopts the first structure, in the motor grid-connected state, the two ends of the second winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively; in the motor grid-disconnected state, the two ends of the first winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively.

[0014] And / or,

[0015] In the case where the inverter adopts the second structure, the inverter further includes a first capacitor and a second capacitor. The first terminal of the first capacitor is connected to the positive terminal of the DC bus voltage, the second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is connected to the inverting terminal of the DC bus voltage.

[0016] When the motor is connected to the grid, the two ends of the second winding are electrically connected to the source of the upper tube of the A bridge arm and the second end of the first capacitor, respectively, and the upper tube of the B bridge arm and the lower tube of the B bridge arm are both turned off.

[0017] When the motor is disconnected from the grid, the two ends of the first winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively.

[0018] And / or,

[0019] The number of turns in the first winding is greater than the number of turns in the second winding;

[0020] And / or,

[0021] The no-load back EMF of the first winding is in phase with the no-load back EMF of the second winding.

[0022] This disclosure also provides a control method for a single-phase permanent magnet motor, the control method being applied to the aforementioned single-phase permanent magnet motor, the control method comprising:

[0023] The relay switching combination state is set according to the grid connection and disconnection requirements so that the single-phase permanent magnet motor is in grid connection state or grid disconnection state.

[0024] Optionally, the control method further includes:

[0025] In response to the second winding being connected to the inverter, the single-phase permanent magnet motor is subjected to closed-loop control.

[0026] Optionally, the closed-loop control of the single-phase permanent magnet motor includes:

[0027] Obtain the real-time speed and position of the motor rotor;

[0028] The grid-connected synchronous speed is used as the reference value of the motor rotor speed. The first difference between the reference value of the speed and the real-time speed is processed by the speed controller and the limiter to obtain the speed control result. The speed control result is used as the reference value of the current amplitude.

[0029] The product of the reference value of the current amplitude and the current parameter is used as the current reference value of the motor current; wherein, the current parameter is related to the electrical angle of the motor rotor.

[0030] The second difference between the current reference value and the actual current value of the motor is used by the current controller to obtain the voltage command for the motor.

[0031] The target algorithm is determined from the single-phase full-bridge inverter PWM (Pulse Width Modulation) algorithm and the single-phase half-bridge inverter PWM algorithm based on the structure adopted by the inverter.

[0032] The voltage command is processed by the target algorithm to obtain the drive signals for the four power switching transistors in the inverter.

[0033] Alternatively, the current parameter can be expressed using the following formula:

[0034] Current parameter = sinθ;

[0035] Where θ represents the electrical angle of the motor rotor.

[0036] This disclosure also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and used to run on the processor, wherein the processor executes the computer program to implement the aforementioned control method for a single-phase permanent magnet motor.

[0037] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned control method for a single-phase permanent magnet motor.

[0038] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this disclosure.

[0039] The positive improvements of this disclosure are as follows: When a single-phase permanent magnet motor is connected to the grid, the first winding is connected to the grid while the second winding is powered by an inverter and controlled in a closed loop. When the motor speed fluctuates, the second winding can actively generate electromagnetic torque to suppress speed fluctuations by controlling the current, thus eliminating motor speed oscillations and improving operational stability. Furthermore, by setting the difference / ratio of the number of turns in the first and second windings, the first winding provides power while the current in the second winding is limited to a very small value, and the second winding only plays a role in suppressing fluctuations. The inverter losses are far less than in the off-grid scenario, maintaining efficiency advantages while enhancing grid-connected operation stability. Compared to a single-phase permanent magnet motor system under frequency conversion control, system efficiency is significantly improved; compared to direct grid connection of a single-phase permanent magnet motor, the problems of grid-connected speed oscillation and divergence are solved, improving system operational stability. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0041] Figure 2 This is a schematic diagram of the drive circuit of a single-phase permanent magnet motor according to Embodiment 1 of this disclosure;

[0042] Figure 3 A schematic diagram of the drive circuit for another structure of a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0043] Figure 4 This is a flowchart of a control method for a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure;

[0044] Figure 5 This is a control block diagram illustrating an example of closed-loop control of a single-phase permanent magnet motor, as provided in Embodiment 2 of this disclosure.

[0045] Figure 6 A flowchart illustrating a specific implementation of step S12 of a control method for a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure;

[0046] Figure 7 This is a schematic diagram of the structure of a prior art single-winding grid-connected drive circuit in an example of a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure;

[0047] Figure 8 Simulation results of a prior art single-winding grid-connected drive circuit in an example of a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure;

[0048] Figure 9 The speed waveform for implementing the control method of this scheme is shown in an example of a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure.

[0049] Figure 10 The current of the first winding and the second winding of the control method of this scheme is implemented in an example of a single-phase permanent magnet motor provided in Embodiment 2 of this disclosure;

[0050] Figure 11 This is a schematic diagram of the structure of an electronic device provided in Embodiment 3 of this disclosure. Detailed Implementation

[0051] The present disclosure is further illustrated below by way of embodiments, but the present disclosure is not limited to the scope of the embodiments described herein.

[0052] The prefixes such as "first" and "second" used in this disclosure are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this disclosure does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not be construed as an unnecessary limitation. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0053] Example 1

[0054] This disclosure provides a single-phase permanent magnet motor, with reference to... Figure 1 A single-phase permanent magnet motor includes: a stator core 1, a permanent magnet 2, a rotor core 3, a shaft 4, a first winding RZ1 and a second winding RZ2 wound on the stator teeth, an inverter, and several relays.

[0055] The relay is used to connect the first winding to the grid voltage and the second winding to the inverter when the motor is in grid-connected state, by setting it to the first switching combination state.

[0056] The inverter, relay, first winding RZ1, and second winding RZ2 are part of the motor drive circuit. The inverter may include several power switching transistors to construct a single-phase full-bridge inverter or a single-phase half-bridge inverter to control the motor.

[0057] Figure 2 and Figure 3 Two drive circuit structures are shown respectively, mainly reflecting the two structures used in the inverter, S A S A '、S B and S B 'There are four power switching transistors, D' A D A '、D B and D BIt's a diode, U dc It is the DC bus voltage of the inverter, U ac It is the grid voltage. S1 to S5 are five relays used to control the switching of the winding's grid-connected / disconnected state.

[0058] Figure 2 In the process of connecting the motor to the grid, disconnecting relays S2 and S3 and closing relays S1, S4, and S5 (first switch combination state) allows the two ends of the first winding RZ1 to be directly connected to the grid voltage U. ac S A S A '、S B and S B 'and its corresponding diode (D) A D A '、D B and D B This constitutes a single-phase full-bridge inverter, with the second winding RZ2 connected to the inverter for closed-loop control.

[0059] Figure 3 In the process of connecting the motor to the grid, disconnecting relays S2 and S3 and closing relays S1, S4, and S5 (first switch combination state) allows the two ends of the first winding RZ1 to be directly connected to the grid voltage U. ac S A S A 'and its corresponding diode (D) A and D A ') and capacitors C1 and C2 are connected together to form a single-phase half-bridge inverter, S B and S B 'and its corresponding diode (D) B and D B When the inverter is not in operation, the second winding RZ2 is connected to the inverter for closed-loop control.

[0060] Single-phase permanent magnet motors have relatively low inherent damping, resulting in poor stability during direct grid-connected operation. They are prone to oscillation, loss of synchronism, and eventual shutdown. However, if the second winding is powered by an inverter and under closed-loop control while the first winding is connected to the grid, the second winding can actively generate electromagnetic torque to suppress speed fluctuations when the motor speed fluctuates. This eliminates speed oscillations and improves operational stability. As long as the second winding is powered by an inverter and under closed-loop control, motor speed oscillations can be eliminated to a certain extent.

[0061] Preferably, the number of turns in the first winding RZ1 is greater than the number of turns in the second winding RZ2, and the no-load back EMF of the first winding RZ1 is in phase with the no-load back EMF of the second winding RZ2. The in-phase relationship between the no-load back EMF of the first winding RZ1 and the no-load back EMF of the second winding RZ2 better eliminates motor speed oscillations and improves operational stability. Furthermore, since the number of turns in the first winding RZ1 is greater than that in the second winding RZ2, during grid-connected operation, the motor can primarily generate power from the first winding RZ1, with the second winding RZ2 only serving to suppress fluctuations. Therefore, the current in the second winding RZ2 can be limited to a very small value. The inverter's losses mainly consist of switching losses and conduction losses. The conduction loss is proportional to the conduction time (i.e., the duty cycle of the power device's switching signal), the square of the current, and the on-state resistance. After the current in the second winding RZ2 is limited to a very small value, the conduction time also decreases proportionally. Therefore, although this grid-connected scheme requires an inverter, the inverter's losses are much smaller than in the case of no grid connection, thus maintaining the efficiency advantage and enhancing the stability of grid-connected operation.

[0062] In this embodiment, when the single-phase permanent magnet motor is running in grid-connected mode, the first winding is connected to the grid while the second winding is powered by an inverter and subjected to closed-loop control. When the motor speed fluctuates, the second winding can actively generate electromagnetic torque to suppress speed fluctuations by controlling the current, thus eliminating motor speed oscillations and improving operational stability. Furthermore, by setting the difference / ratio of the number of turns in the first and second windings, the first winding provides power while the current in the second winding is limited to a very small value, and the second winding only plays a role in suppressing fluctuations. The inverter losses are far less than in the off-grid scenario, maintaining efficiency advantages while enhancing grid-connected operation stability. Compared to a single-phase permanent magnet motor system under frequency conversion control, the system efficiency is significantly improved; compared to direct grid connection of a single-phase permanent magnet motor, the problems of grid-connected speed oscillation and divergence are solved, improving system operational stability.

[0063] In one embodiment, the relay is also used to connect the first winding RZ1 to the inverter for operation in the motor off-grid state by setting it to a second switch combination state, and to de-energize the second winding RZ2.

[0064] Figure 2 In the middle, when the motor is disconnected from the grid, S A S A '、S B and S B 'and its corresponding diode (D) A D A '、D B and D BThis constitutes a single-phase full-bridge inverter. Closing relays S2 and S3 and opening relays S1, S4 and S5 (second switch combination state) allows the first winding RZ1 to be connected to the inverter for operation. The speed-current dual closed-loop control strategy of the existing technology is used for closed-loop control and speed regulation, while the second winding RZ2 is open.

[0065] Figure 3 In the middle, when the motor is disconnected from the grid, S A S A '、S B and S B 'and its corresponding diode (D) A D A '、D B and D B The first winding RZ1 and capacitors C1 and C2 form a single-phase full-bridge inverter. Closing relays S2 and S3 and opening relays S1, S4 and S5 (second switch combination state) allows the first winding RZ1 to be connected to the inverter for operation. The speed-current dual closed-loop control strategy of the existing technology is used for closed-loop control and speed regulation, and the second winding RZ2 is open.

[0066] In one embodiment, refer to Figure 2 and Figure 3 The inverter includes four power switching transistors and corresponding diodes for each power switching transistor.

[0067] The source of each power switch is electrically connected to the anode of the corresponding diode, the drain of each power switch is electrically connected to the cathode of the corresponding diode, and the gate of each power switch is connected to an external control signal.

[0068] The four power switching transistors include the upper transistor S on the A-arm bridge. A A-bridge lower tube S A '、B bridge arm upper pipe S B and B bridge arm lower tube S B '.

[0069] A bridge arm upper pipe S A The drain and the upper S-type tube of the B-bridge arm B The drains of all are connected to the DC bus voltage U dc The positive terminal, S on the A bridge arm A The source electrode is also related to the lower tube S of the A bridge arm. A The drain connection of ', the upper transistor S on the B-arm of the bridge. B The source electrode is also related to the lower tube S of the B bridge arm. B The drain connection of ', lower transistor S of bridge arm A. A 'The source and the lower B-arm of the bridge S' B The sources of ' are all connected to the DC bus voltage U dc The inverting input.

[0070] Among them, diode D A D A '、D B and D B 'Corresponding to S on the upper pipe of bridge arm A respectively A A-bridge lower tube S A '、B bridge arm upper pipe S B and B bridge arm lower tube S B ', U dc It is the DC bus voltage of the inverter, U ac It is the grid voltage.

[0071] In one embodiment, when the inverter adopts the first structure, the two ends of the second winding RZ2 are respectively connected to the upper tube S of the A bridge arm in the motor grid-connected state. A The source and the upper S-band of the B-bridge arm B The source terminals are electrically connected, and when the motor is disconnected from the grid, the two ends of the first winding RZ1 are respectively connected to the upper tube S of the A bridge arm. A The source and the upper S-band of the B-bridge arm B The source electrode is connected.

[0072] in, Figure 2 The first configuration of the inverter is shown.

[0073] In one embodiment, when the inverter adopts the second structure, the inverter further includes a first capacitor C1 and a second capacitor C2, with the first terminal of the first capacitor C1 connected to the DC bus voltage U. dc The positive terminal of the capacitor is connected to the second terminal of the first capacitor C1, which is electrically connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the DC bus voltage U. dc The inverting input.

[0074] When the motor is connected to the grid, the two ends of the second winding RZ2 are respectively connected to the upper tube S of the A bridge arm. A The source of the transistor is electrically connected to the second terminal of the first capacitor C1, and the upper transistor S on the B-arm is connected to the second terminal of the first capacitor C1. B and B bridge arm lower tube S B All are closed.

[0075] With the motor disconnected from the grid, the two ends of the first winding RZ1 are respectively connected to the upper tube S of the A bridge arm. A The source and the upper S-band of the B-bridge arm B The source electrode is connected.

[0076] in, Figure 3 This illustrates the case where the inverter employs the second structure.

[0077] In one embodiment, the number of turns of the first winding RZ1 is greater than the number of turns of the second winding RZ2.

[0078] In this grid-connected configuration, since the number of turns in the first winding RZ1 is greater than that in the second winding RZ2, the motor can primarily generate power from the first winding RZ1 during grid-connected operation. The second winding RZ2 only serves to suppress fluctuations, thus limiting the current in the second winding RZ2 to a very small value. Inverter losses mainly consist of switching losses and conduction losses. Conduction losses are proportional to the conduction time (i.e., the duty cycle of the power device's switching signal), the square of the current, and the on-state resistance. With the current in the second winding RZ2 limited to a very small value, the conduction time also decreases proportionally. Therefore, although this grid-connected scheme requires an inverter, its losses are far less than in the off-grid scenario, maintaining efficiency advantages while enhancing the stability of grid-connected operation.

[0079] In one embodiment, the no-load back EMF of the first winding RZ1 is in phase with the no-load back EMF of the second winding RZ2.

[0080] The fact that the no-load back EMF of the first winding RZ1 is in phase with the no-load back EMF of the second winding RZ2 can better eliminate the speed oscillation of the motor and improve the stability of operation.

[0081] Example 2

[0082] Figure 4 The flowchart illustrates a control method for a single-phase permanent magnet motor provided as an exemplary embodiment of this disclosure. The control method is applied to the aforementioned single-phase permanent magnet motor and includes:

[0083] S11. Set the relay switching combination state according to the grid connection and disconnection requirements so that the single-phase permanent magnet motor is in grid connection state or grid disconnection state.

[0084] Among them, grid connection and grid disconnection requirements mean that the motor needs to be in grid connection state or in grid disconnection state.

[0085] for Figure 2 and Figure 3 For example, the switch combination state is the first switch combination state, that is, the relays S2 and S3 are open, the relays S1, S4 and S5 are closed, and the motor is in the motor grid-connected state; the switch combination state is the second switch combination state, that is, the relays S2 and S3 are closed, the relays S1, S4 and S5 are open, and the motor is in the motor grid-disconnected state.

[0086] In this embodiment, when the single-phase permanent magnet motor is running in grid-connected mode, the first winding is connected to the grid while the second winding is powered by an inverter and subjected to closed-loop control. When the motor speed fluctuates, the second winding can actively generate electromagnetic torque to suppress speed fluctuations by controlling the current, thus eliminating motor speed oscillations and improving operational stability. Furthermore, by setting the difference / ratio of the number of turns in the first and second windings, the first winding provides power while the current in the second winding is limited to a very small value, and the second winding only plays a role in suppressing fluctuations. The inverter losses are far less than in the off-grid scenario, maintaining efficiency advantages while enhancing grid-connected operation stability. Compared to a single-phase permanent magnet motor system under frequency conversion control, the system efficiency is significantly improved; compared to direct grid connection of a single-phase permanent magnet motor, the problems of grid-connected speed oscillation and divergence are solved, improving system operational stability.

[0087] In one embodiment, refer to Figure 4 The control methods also include:

[0088] S12, in response to the second winding being connected to the inverter, performs closed-loop control on the single-phase permanent magnet motor.

[0089] in, Figure 5 The diagram shows an example of closed-loop control of a single-phase permanent magnet motor after the second winding is connected to the inverter. n* represents the reference speed of the motor rotor (i.e., the set speed when the motor is connected to the grid), n represents the real-time speed of the motor rotor, θ represents the electrical angle of the motor rotor, sinθ represents the current parameter used, i* represents the reference current of the motor current, i represents the actual current value of the motor, u* represents the voltage command of the motor, the single-phase SVPWM sends the drive signal of the power switching transistor in the inverter to the inverter, and M is the winding connected to the inverter.

[0090] In one embodiment, refer to Figure 6 Step S12, "performing closed-loop control of the single-phase permanent magnet motor," includes:

[0091] S121. Obtain the real-time speed and position of the motor rotor.

[0092] S122. The grid-connected synchronous speed is used as the reference value of the motor rotor speed. The first difference between the speed reference value and the real-time speed is used by the speed controller and the limiter to obtain the speed control result. The speed control result is used as the reference value of the current amplitude.

[0093] S123. The product of the current amplitude reference value and the current parameter is used as the current reference value of the motor current. Among them, the current parameter is related to the electric angle of the motor rotor.

[0094] S124. The second difference between the current reference value and the actual motor current value is used by the current controller to obtain the motor voltage command.

[0095] S125. Determine the target algorithm from the single-phase full-bridge inverter PWM algorithm and the single-phase half-bridge inverter PWM algorithm according to the structure adopted by the inverter.

[0096] S126. The voltage command is processed by the target algorithm to obtain the drive signals for the four power switching transistors in the inverter.

[0097] The real-time speed and position of the motor rotor can be obtained through position sensors or sensorless algorithms. The actual motor current value can be obtained through phase current sampling.

[0098] In one embodiment, the current parameter is expressed by the following formula:

[0099] Current parameter = sinθ.

[0100] Where θ represents the electrical angle of the motor rotor.

[0101] The following is an example of a single-phase permanent magnet motor and a control method for implementing a single-phase permanent magnet motor.

[0102] A single-phase permanent magnet motor with two windings, such as Figure 1 As shown. The first winding RZ1 has 2420 turns, and the second winding RZ2 has 400 turns. 705 turns are wound on each of the three adjacent teeth in a clockwise direction, and 305 turns are wound on the fourth tooth. These are connected in series according to the principle that the no-load back electromotive force is in phase to form the first winding RZ1. Another 400 turns are wound on the fourth tooth to form the second winding RZ2.

[0103] The motor drive circuit is as follows Figure 2 As shown, S A S A '、S B and S B 'There are four power switching transistors, D' A D A '、D B and D B It's a diode, U dc It is the DC bus voltage of the inverter, U ac It is the grid voltage. S1 to S5 are five relays used to control the switching of the winding's grid-connected / grid-disconnected state. The on / off states of S1, S4, and S5 are the same, and the on / off states of S2 and S3 are the same.

[0104] When the motor is connected to the grid, disconnecting relays S2 and S3 and closing relays S1, S4, and S5 (first switch combination state) allows the two ends of the first winding RZ1 to be directly connected to the grid voltage U. ac S A S A '、SB and S B 'and its corresponding diode (D) A D A '、D B and D B This constitutes a single-phase full-bridge inverter, with the second winding RZ2 connected to the inverter for closed-loop control.

[0105] When the motor is disconnected from the grid, S A S A '、S B and S B 'and its corresponding diode (D) A D A '、D B and D B This constitutes a single-phase full-bridge inverter. Closing relays S2 and S3 and opening relays S1, S4, and S5 (second switch combination state) allows the first winding RZ1 to operate independently in the inverter. A speed-current dual closed-loop control strategy is used for closed-loop control and speed regulation, while the second winding RZ2 is open. At this time, the first winding RZ1 is controlled by the inverter, which controls the motor startup. When a command is received from the upper layer that the motor needs to operate in grid-connected mode, S2 and S3 are opened, and S1, S4, and S5 are closed. The first winding RZ1 is then connected to the grid, and the second winding RZ2 is controlled by the inverter, i.e., switching to grid-connected motor operation.

[0106] The control block diagram of the second winding RZ2 when the motor is operating in grid-connected mode is as follows: Figure 5 As shown. Figure 5 The single-phase inverter in the middle is Figure 2 The single-phase inverter in the middle, Figure 5 M in the text is Figure 2 The second winding RZ2 is described in this embodiment. The control method described in this embodiment is implemented in a microcontroller and its peripheral circuits. n and θ are the motor speed and electrical angle, respectively, which are calculated by sampling the motor rotor position using a Hall sensor mounted on the motor. n* is the motor speed reference value (set speed) when the motor is connected to the grid. Subtracting n yields the speed error signal. The speed error signal is input to the speed controller, and the output is limited and multiplied by sinθ to obtain the current reference value i* of the second winding RZ2. The actual current value i is obtained by sampling by the ADC in the circuit. The current error signal passes through the current controller and outputs the voltage reference value u* of the second winding RZ2. The voltage reference value is then modulated by single-phase SVPWM to obtain the switching signals driving the four power devices SA, SA', SB, and SB'.

[0107] The following simulation results compare the current situation with direct grid connection of a single winding. The hardware drive circuit for direct grid connection of a single winding in the prior art is as follows: Figure 7As shown, the grid connection simulation results are as follows: Figure 8 As shown, when S1 and S3 are disconnected and S2 is closed at 1.5s, the motor speed exhibits divergent oscillation and gradually becomes unstable.

[0108] The grid connection simulation results of this embodiment are as follows: Figure 9 and 10 As shown, at 1.5s, S2 and S4 are opened, and S1 and S3 are closed. At 2s, [the following is a separate, unrelated statement:] Figure 5 The limiting value of the intermediate speed controller has been changed from no limiting to a limiting value of ±0.05A (amperes). Figure 9 The rotational speed waveform of this process is shown. Figure 10 i1 and i2 are the currents of the first winding RZ1 and the second winding RZ2, respectively. It can be seen that the speed oscillates after switching but gradually converges and stabilizes.

[0109] Example 3

[0110] Figure 11 This is a schematic diagram of the structure of an electronic device according to an example embodiment of the present disclosure. The electronic device includes a memory, a processor, and a computer program stored in the memory and used to run on the processor. When the processor executes the computer program, it implements the control method of the single-phase permanent magnet motor described in any of the above embodiments. Figure 11 The electronic device 90 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments disclosed herein.

[0111] like Figure 11 As shown, the electronic device 90 can be manifested as a general-purpose computing device, such as a server device. The components of the electronic device 90 may include, but are not limited to: at least one processor 91, at least one memory 92, and a bus 93 connecting different system components (including memory 92 and processor 91).

[0112] Bus 93 includes a data bus, an address bus, and a control bus.

[0113] The memory 92 may include volatile memory, such as random access memory (RAM) 921 and / or cache memory 922, and may further include read-only memory (ROM) 923.

[0114] The memory 92 may also include a program tool 925 (or utility) having a set (at least one) program module 924, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0115] The processor 91 executes various functional applications and data processing by running computer programs stored in the memory 92, such as the control method for a single-phase permanent magnet motor provided in any of the above embodiments.

[0116] Electronic device 90 can also communicate with one or more external devices 94 (e.g., keyboard, pointing device, etc.). This communication can be performed through input / output (I / O) interface 95. Furthermore, electronic device 90 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public network, such as the Internet) via network adapter 96. As shown, network adapter 96 communicates with other modules of electronic device 90 via bus 93. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with electronic device 90, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0117] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0118] Example 4

[0119] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the control method for a single-phase permanent magnet motor as described above.

[0120] The program code for executing the computer program product of this disclosure can be written in any combination of one or more programming languages, and the program code can be executed entirely on a user device, partially on a user device, as a stand-alone software package, partially on a user device and partially on a remote device, or entirely on a remote device.

[0121] While specific embodiments of this disclosure have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this disclosure is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this disclosure, but all such changes and modifications fall within the scope of protection of this disclosure.

Claims

1. A single-phase permanent magnet motor, characterized in that, The single-phase permanent magnet motor includes: a first winding and a second winding wound on stator teeth, an inverter, and several relays; The relay is used to connect the first winding to the grid voltage and connect the second winding to the inverter when the motor is in grid-connected state, by setting it to a first switch combination state.

2. The single-phase permanent magnet motor as described in claim 1, characterized in that, The relay is also used to connect the first winding to the inverter for operation when the motor is disconnected from the grid, by setting it to a second switch combination state, and to de-energize the second winding.

3. The single-phase permanent magnet motor as described in claim 1, characterized in that, The inverter includes four power switching transistors and diodes corresponding to each power switching transistor. The source of each power switch is electrically connected to the anode of the corresponding diode, the drain of each power switch is electrically connected to the cathode of the corresponding diode, and the gate of each power switch is connected to an external control signal. The four power switching transistors include the upper transistor of bridge arm A, the lower transistor of bridge arm A, the upper transistor of bridge arm B, and the lower transistor of bridge arm B; The drain of the upper transistor in bridge arm A and the drain of the upper transistor in bridge arm B are both connected to the positive terminal of the DC bus voltage. The source of the upper transistor in bridge arm A is also electrically connected to the drain of the lower transistor in bridge arm A. The source of the upper transistor in bridge arm B is also electrically connected to the drain of the lower transistor in bridge arm B. The source of the lower transistor in bridge arm A and the source of the lower transistor in bridge arm B are both connected to the inverting terminal of the DC bus voltage.

4. The single-phase permanent magnet motor as described in claim 3, characterized in that, When the inverter adopts the first structure, in the motor grid-connected state, the two ends of the second winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively. In the motor grid-disconnected state, the two ends of the first winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively. And / or, In the case where the inverter adopts the second structure, the inverter further includes a first capacitor and a second capacitor. The first terminal of the first capacitor is connected to the positive terminal of the DC bus voltage, the second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is connected to the inverting terminal of the DC bus voltage. When the motor is connected to the grid, the two ends of the second winding are electrically connected to the source of the upper tube of the A bridge arm and the second end of the first capacitor, respectively, and the upper tube of the B bridge arm and the lower tube of the B bridge arm are both turned off. When the motor is disconnected from the grid, the two ends of the first winding are electrically connected to the source of the upper tube of the A bridge arm and the source of the upper tube of the B bridge arm, respectively. And / or, The number of turns in the first winding is greater than the number of turns in the second winding; And / or, The no-load back EMF of the first winding is in phase with the no-load back EMF of the second winding.

5. A control method for a single-phase permanent magnet motor, characterized in that, The control method is applied to a single-phase permanent magnet motor as described in any one of claims 1-4, and the control method includes: The relay switching combination state is set according to the grid connection and disconnection requirements so that the single-phase permanent magnet motor is in grid connection state or grid disconnection state.

6. The control method for a single-phase permanent magnet motor as described in claim 5, characterized in that, The control method further includes: In response to the second winding being connected to the inverter, the single-phase permanent magnet motor is subjected to closed-loop control.

7. The control method for a single-phase permanent magnet motor as described in claim 5, characterized in that, The closed-loop control of the single-phase permanent magnet motor includes: Obtain the real-time speed and position of the motor rotor; The grid-connected synchronous speed is used as the reference value of the motor rotor speed. The first difference between the reference value of the speed and the real-time speed is processed by the speed controller and the limiter to obtain the speed control result. The speed control result is used as the reference value of the current amplitude. The product of the reference value of the current amplitude and the current parameter is used as the current reference value of the motor current; wherein, the current parameter is related to the electrical angle of the motor rotor. The second difference between the current reference value and the actual current value of the motor is used by the current controller to obtain the voltage command for the motor. The target algorithm is determined from the single-phase full-bridge inverter PWM algorithm and the single-phase half-bridge inverter PWM algorithm based on the structure adopted by the inverter. The voltage command is processed by the target algorithm to obtain the drive signals for the four power switches in the inverter.

8. The control method for a single-phase permanent magnet motor as described in claim 7, characterized in that, The current parameter is expressed by the following formula: Current parameter = sinθ; Where θ represents the electrical angle of the motor rotor.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and for running on the processor, characterized in that, When the processor executes the computer program, it implements the control method for a single-phase permanent magnet motor as described in any one of claims 5 to 8.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the control method for a single-phase permanent magnet motor as described in any one of claims 5-8.

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