Single-phase permanent magnet motor torque ripple suppression method, device, medium and program product

Abstract

This disclosure provides a method, device, medium, and program product for suppressing torque ripple in a single-phase permanent magnet motor. The method includes: acquiring the current motor current; acquiring a lookup table combining the load torque with the fundamental component and several odd-order harmonic components of the corresponding motor current; extracting the actual fundamental and harmonic values ​​from the current motor current; using a torque reference value as the load torque value, obtaining the fundamental and harmonic reference values ​​based on the torque reference value and the lookup table; obtaining the component differences between the reference values ​​and the corresponding actual values; generating a voltage reference value component through a corresponding current controller for each component difference; using the sum of all voltage reference value components as the voltage reference value; and controlling the switching signals of the power devices of the single-phase inverter based on the voltage reference value. This disclosure effectively reduces the motor's torque ripple by injecting harmonic current, while avoiding delays caused by extracting the fundamental and harmonic components and adverse effects on system performance.

Description

Technical Field

[0001] This disclosure relates to the field of motor technology, and in particular to a method, device, medium, and program product for suppressing torque ripple in a single-phase permanent magnet motor. Background Technology

[0002] Single-phase permanent magnet motors are widely used in fans, pumps, compressors and other fields due to their simple structure and low cost. The existing closed-loop control method of single-phase permanent magnet motors mainly generates a power device drive signal with a fixed relative position to the rotor through a specific modulation method based on the rotor position, so as to ensure that the voltage input to the stator of the motor is a sine wave or a square wave.

[0003] The magnetomotive force generated by the stator current of a single-phase permanent magnet motor is pulsating, which is an inherent characteristic of the motor. This results in torque pulsation in the single-phase permanent magnet motor. Currently, torque pulsation is usually reduced by optimizing the design of the motor body, but there is a lack of means to suppress torque pulsation in terms of control. Summary of the Invention

[0004] The technical problem to be solved by this disclosure is to overcome the lack of means in the prior art to suppress torque ripple of single-phase permanent magnet motors, and to provide a method, device, medium and program product for suppressing torque ripple of single-phase permanent magnet motors.

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

[0006] This disclosure provides a method for suppressing torque ripple in a single-phase permanent magnet motor, the method comprising:

[0007] Obtain the current motor current, and obtain a lookup table of the fundamental component and several odd-order harmonic components of the load torque and the corresponding motor current; wherein, the fundamental component and the combination of harmonic components are obtained with the goal of minimizing the pulsation of the shaft output torque.

[0008] Extract the fundamental and harmonic actual values ​​from the current motor current;

[0009] The load torque is taken as a reference value, and the fundamental reference value and harmonic reference value are obtained based on the torque reference value and the lookup table; wherein, the torque reference value is obtained by the difference between the set speed and the actual speed through the speed regulator;

[0010] The component differences between the fundamental reference value and the harmonic reference value and the corresponding actual fundamental and harmonic values ​​are obtained respectively.

[0011] Each of the aforementioned component differences generates a voltage reference value component through a corresponding current controller. The sum of all voltage reference value components is used as the voltage reference value, and the switching signals of the single-phase inverter power devices are controlled according to the voltage reference value.

[0012] Optionally, the method for suppressing torque ripple in a single-phase permanent magnet motor further includes:

[0013] The no-load back EMF and cogging torque waveforms of the motor are obtained through electromagnetic simulation of the motor. Fourier decomposition of the no-load back EMF is performed to obtain the expression of the no-load back EMF containing the amplitude and phase information of the fundamental wave and each harmonic.

[0014] By injecting several odd-order harmonics into the current to suppress torque pulsation, we obtain the current expression containing harmonics and the torque expression of the motor.

[0015] The torque component generated by the interaction between the i-th harmonic of the back electromotive force and the j-th harmonic of the current is obtained based on the no-load back electromotive force expression, the current expression, and the torque expression; where i and j are both positive odd numbers.

[0016] Based on the no-load back EMF expression, the current expression, the torque expression, the torque components, and the output condition expression, with the goal of minimizing the pulsation of the shaft output torque, the values ​​of the fundamental component and odd-order harmonic components of the current corresponding to each load torque are calculated and a lookup table is constructed; wherein, the output condition expression indicates that the average value of the total torque output by the motor is equal to the load torque value of the motor.

[0017] Optionally, the following formulas can be used to express the no-load back electromotive force, the current, the torque, the torque component, and the output condition:

[0018]

[0019]

[0020] The objective of minimizing the ripple of the shaft output torque is expressed as:

[0021]

[0022] Where E0 represents the unloaded back electromotive force, i represents the harmonic order of the back electromotive force, and ψ i Indicates the amplitude of the permanent magnet flux harmonics. The initial phase of the back electromotive force harmonic is represented by ω, the electrical angular frequency of the motor is represented by t, and i represents time. s T represents the motor current containing harmonics. e T represents the electromagnetic torque of the motor.c Ω represents the cogging torque, and T represents the mechanical angular velocity of the motor. ij T represents the torque component. ampij This represents the average value of the corresponding torque components generated by the i-th harmonic of the back electromotive force and the j-th harmonic of the current. T represents the average value of the total torque output by the motor. L This indicates the load torque value of the motor.

[0023] Optionally, extracting the fundamental and harmonic actual values ​​from the current motor current includes:

[0024] The current motor current is virtualized as the phase current of an m-phase motor; where m is the highest order of the harmonics to be extracted, and m is an odd number greater than 1.

[0025] The phase current is decoupled into m-phase vector space to map the fundamental wave and several harmonics to n subspaces respectively; wherein, one of the subspaces corresponds to the fundamental wave or an odd-order harmonic, and n = (m+1) / 2.

[0026] Optionally, the step of virtually converting the current motor current into the phase current of an m-phase motor includes:

[0027] The current motor current is phase-shifted m-1 times, and each phase shift causes the phase of the current motor current to lag by 2π / m electrical angles to construct the m-phase motor and obtain the phase current of the m-phase motor.

[0028] The step of decoupling the phase current using m-phase vector space to map the fundamental wave and several harmonics to n subspaces includes:

[0029] The phase current is transformed from the m-phase vector to the decoupled vector space by a transformation matrix; wherein, for the fundamental wave and harmonics below the m-2th order, there is a pair of mutually orthogonal fundamental wave components or harmonic components on the two axes of the corresponding subspace; for the m-th harmonic, the m-th harmonic is located on one axis of the corresponding subspace.

[0030] Optionally, the phase current of the m-phase motor, the phase current in the decoupled vector space, and the transformation matrix can be represented by the following formulas:

[0031]

[0032] [i α i β i z1 i z2 … i o1 ] T =T VSD[i1 i2 i3 … i m ] T ;

[0033]

[0034] α = 2π / m;

[0035] Among them, i s Represents the motor current containing harmonics, i1...i m Let T represent the phase current of each phase, ω represent the electrical angular frequency of the motor, t represent time, m represent the number of phases of the virtual motor, f(ωt) represent the current motor current, and T represent the current of the motor. VSD Denotes the transformation matrix, [i α i β i z1 i z2 … i o1 ] represents the phase current in the decoupled vector space, i α and i β i represents a pair of mutually orthogonal fundamental components in the subspace corresponding to the fundamental wave. z1 and i z2 This represents a pair of mutually orthogonal harmonic components in the subspace corresponding to the 3rd harmonic, and so on up to the (m-2)th harmonic, i o1 This represents the harmonic components of the subspace corresponding to the m-th harmonic.

[0036] Optionally, each of the component differences generates a voltage reference value component through a corresponding current controller, and the sum of all voltage reference value components is used as the voltage reference value, including:

[0037] For the fundamental wave and harmonics below the m-2 order, each pair of orthogonal components mapped to the corresponding subspace is transformed to the corresponding frequency rotating coordinate system through Park transformation, and a pair of first DC components on the dq axis are obtained in each subspace. The difference between each first DC component and the reference value of the corresponding component is used to generate a first voltage reference value component through a PI controller.

[0038] For the mth harmonic, an AC component is mapped to an axis in the corresponding subspace, and the difference between the AC component and the reference value of the corresponding component is used to generate a second voltage reference value component through a PR controller.

[0039] The α-axis component obtained after the first voltage reference value component undergoes inverse Park transformation is used as the sum of the α-axis component and the second voltage reference value component as the voltage reference value.

[0040] 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 method for suppressing torque ripple in a single-phase permanent magnet motor.

[0041] This disclosure also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned method for suppressing torque ripple in a single-phase permanent magnet motor.

[0042] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the torque ripple suppression method for a single-phase permanent magnet motor as described above.

[0043] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of this disclosure.

[0044] The positive and progressive effects of this disclosure are as follows: This disclosure converts the current motor current into the phase current of a virtual multiphase motor, performs multiphase vector space decoupling on the phase current to map the fundamental and harmonic waves to different subspaces for extraction, and then injects harmonic current into the motor current based on the extracted fundamental and harmonic waves. Through the injection of harmonic current, the torque ripple of the motor is effectively reduced, while avoiding the delay caused by the extraction of fundamental and harmonic waves, thus avoiding adverse effects on the performance of the single-phase permanent magnet motor system. Attached Figure Description

[0045] Figure 1 A flowchart of a method for suppressing torque ripple in a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0046] Figure 2 A flowchart illustrating a specific implementation of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0047] Figure 3 A flowchart illustrating a specific implementation of step S12 of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0048] Figure 4 A flowchart illustrating a specific implementation of step S15 of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0049] Figure 5 The diagram shows the structure of a drive circuit for a single-phase permanent magnet motor, which is an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0050] Figure 6The no-load back electromotive force waveform of a single-phase permanent magnet motor is an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0051] Figure 7 The no-load back electromotive force FFT result of a single-phase permanent magnet motor is an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0052] Figure 8 An overall control block diagram of a single-phase permanent magnet motor is provided as an example of a torque ripple suppression method for a single-phase permanent magnet motor according to Embodiment 1 of this disclosure.

[0053] Figure 9 A virtual five-phase motor is an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure;

[0054] Figure 10 Current decoupling of a virtual five-phase motor is provided as an example of a torque ripple suppression method for a single-phase permanent magnet motor according to Embodiment 1 of this disclosure;

[0055] Figure 11 A diagram showing the motor current waveforms before and after harmonic injection, representing an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0056] Figure 12 The waveform of the fundamental wave in the motor current before and after the injection of harmonics is shown in an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0057] Figure 13 The waveform of the third harmonic in the motor current before and after the injection of harmonics is shown in an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0058] Figure 14 The waveform of the fifth harmonic in the motor current before and after the injection of harmonics is shown in an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0059] Figure 15 The waveforms of the motor shaft output torque and electromagnetic torque before and after harmonic injection are shown in an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0060] Figure 16 The waveform diagram of the motor speed before and after the injection of harmonics is shown in an example of a torque ripple suppression method for a single-phase permanent magnet motor provided in Embodiment 1 of this disclosure.

[0061] Figure 17 This is a schematic diagram of the structure of an electronic device provided in Embodiment 2 of this disclosure. Detailed Implementation

[0062] 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.

[0063] 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.

[0064] Example 1

[0065] Figure 1 A flowchart of a method for suppressing torque ripple in a single-phase permanent magnet motor, provided as an exemplary embodiment of this disclosure, is included. The method for suppressing torque ripple in a single-phase permanent magnet motor includes:

[0066] S11. Obtain the current motor current, and obtain a lookup table of the fundamental component and several odd-order harmonic components of the load torque and the corresponding motor current. The fundamental component and harmonic component combination are obtained with the goal of minimizing the ripple of the shaft output torque.

[0067] S12. Extract the actual value of the fundamental wave and the actual value of the harmonics from the current motor current.

[0068] S13. Using the torque reference value as the load torque value, the fundamental reference value and harmonic reference value are obtained based on the torque reference value and a lookup table. The torque reference value is obtained from the difference between the set speed and the actual speed through the speed regulator.

[0069] S14. Obtain the component differences between the fundamental reference value, the harmonic reference value, and the corresponding actual fundamental value and actual harmonic value.

[0070] S15. Each component difference is used to generate a voltage reference value component through a corresponding current controller. The sum of all voltage reference value components is used as the voltage reference value. The switching signals of the power devices of the single-phase inverter are controlled according to the voltage reference value.

[0071] In single-phase permanent magnet motors, the magnetomotive force generated by the stator current is pulsating, which is an inherent characteristic. When using traditional sinusoidal wave control methods, under the combined effect of pulsating magnetomotive force, cogging torque, and other factors, the motor torque pulsation is very large, typically reaching around 200%, resulting in poor steady-state speed response of the motor.

[0072] The torque of a motor current is actually equal to the sum of the fundamental, third, fifth, and other harmonics of the current multiplied by the sum of the fundamental, third, fifth, and other harmonics of the back electromotive force (EMF), divided by the motor's mechanical angular velocity. Expanding this multiplication result, the total torque is equal to the sum of the torque components generated by the interaction of the fundamental current with the 1st, 3rd, 5th, ... harmonics of the back EMF, the torque components generated by the interaction of the third harmonic of the current with the 1st, 3rd, 5th, ... harmonics of the back EMF, the torque components generated by the interaction of the fifth harmonic of the current with the 1st, 3rd, 5th, ... harmonics of the back EMF, and so on, and so on.

[0073] The fundamental and harmonic waves of the back electromotive force (EMF) interact with the fundamental and harmonic waves of the motor current, partially canceling each other out. For example, the interaction of the 1st (fundamental) and 1st harmonic waves produces 0th and 2nd order torque components; the interaction of the 1st and 3rd harmonic waves produces 2nd and 4th order torque components; and the interaction of the 7th and 9th harmonic waves produces 2nd and 16th order torque components. When i = j, the torque components are 0th and i+j; when i ≠ j, the torque components are ij and i+j. Without harmonic injection, the motor exhibits 2nd order torque ripple. With harmonic injection, by properly distributing the order and magnitude of the harmonics, torque components of the same order generated by different orders of current or back EMF harmonics will cancel each other out (e.g., the 2nd order torque component generated by 1+1 and the 2nd order torque component generated by 1+3), minimizing the total torque ripple. The total torque ripple is calculated as (maximum torque - minimum torque) / average torque.

[0074] The voltage reference value is converted into a switching signal for the power devices of the single-phase inverter through single-phase PWM (pulse width modulation) modulation, thereby controlling the operation of the motor.

[0075] In this embodiment, the current motor current is converted into the phase current of a virtual multiphase motor. The phase current is decoupled into a multiphase vector space to map the fundamental and harmonic waves to different subspaces for extraction. Then, harmonic current is injected into the motor current based on the extracted fundamental and harmonic waves. By injecting harmonic current, the torque ripple of the motor is effectively reduced, while avoiding the delay caused by the extraction of fundamental and harmonic waves, thus avoiding adverse effects on the performance of the single-phase permanent magnet motor system.

[0076] In one embodiment, refer to Figure 2 The methods for suppressing torque ripple in single-phase permanent magnet motors also include:

[0077] S21. Obtain the no-load back EMF and cogging torque waveforms of the motor through electromagnetic simulation. Perform Fourier decomposition on the no-load back EMF to obtain the expression of the no-load back EMF containing the amplitude and phase information of the fundamental wave and each harmonic.

[0078] S22. Inject several odd-order harmonics into the current to suppress torque pulsation, and obtain the current expression containing harmonics and the torque expression of the motor.

[0079] S23. Based on the expressions for no-load back EMF, current, and torque, obtain the torque component generated by the interaction between the i-th harmonic of the back EMF and the j-th harmonic of the current. Here, i and j are both positive odd numbers.

[0080] S24. Based on the expressions for no-load back EMF, current, torque, torque components, and output condition, with the goal of minimizing shaft output torque ripple, calculate and construct a lookup table for the combination of the fundamental component and odd-order harmonic components of the current corresponding to each load torque. The output condition expression indicates that the average value of the total output torque of the motor is equal to the load torque value of the motor.

[0081] The reference values ​​of the fundamental current and each harmonic component corresponding to each load torque are obtained offline and compiled into a lookup table.

[0082] Preferably, the phase of the harmonic current is the same as the phase of the corresponding back electromotive force.

[0083] In one embodiment, the no-load back EMF, current, torque, torque component, and output condition expressions are expressed using the following formulas:

[0084]

[0085] The objective of minimizing the ripple of the shaft output torque is expressed as:

[0086]

[0087] Where E0 represents the no-load back electromotive force, i represents the harmonic order of the back electromotive force, and ψ i Indicates the amplitude of the permanent magnet flux harmonics. The initial phase of the back electromotive force harmonic is represented by ω, the electrical angular frequency of the motor is represented by t, and i represents time. s T represents the motor current containing harmonics. e T represents the electromagnetic torque of the motor. c Ω represents the cogging torque, and T represents the mechanical angular velocity of the motor. ij T represents the torque component. ampij This represents the average value of the corresponding torque components generated by the i-th harmonic of the back electromotive force and the j-th harmonic of the current. T represents the average value of the total output torque of the motor. L This indicates the load torque value of the motor.

[0088] Wherein, the mechanical angular velocity Ω of the motor is equal to 1 / p of the electrical angular velocity ω, and p is the number of pole pairs of the motor.

[0089] Torque T from motor current e From the torque expression, we can see that the torque of the motor current is actually equal to the sum of the fundamental, third, fifth, and other harmonics of the current multiplied by the sum of the fundamental, third, fifth, and other harmonics of the back electromotive force, divided by the mechanical angular velocity of the motor. Expanding this multiplication result, the total torque is equal to the sum of the torque components generated by the interaction of the fundamental current with the first, third, fifth, ... harmonics of the back electromotive force, the torque components generated by the interaction of the third harmonic of the current with the first, third, fifth, ... harmonics of the back electromotive force, the torque components generated by the interaction of the fifth harmonic of the current with the first, third, fifth, ... harmonics of the back electromotive force, and so on, and so on.

[0090] From torque component T ij The expression shows that the torque component is generated by the interaction of the i-th harmonic of the back EMF with the j-th harmonic of the current, or vice versa. For example, the interaction of the 1st and 1st harmonics produces the 0th and 2nd harmonic components; the interaction of the 1st and 3rd harmonics produces the 2nd and 4th harmonic components; and the interaction of the 7th and 9th harmonics produces the 2nd and 16th harmonic components. When i = j, the torque components are 0th and i+j; when i ≠ j, the torque components are ij and i+j. Without harmonic injection, the motor has a 2nd-order torque ripple. With harmonic injection, as long as the order and magnitude of the harmonics are properly distributed, the torque components of the same order generated by different orders of current or back EMF harmonics will cancel each other out (e.g., the 2nd-order torque component generated by 1+1 and the 2nd-order torque component generated by 1+3), minimizing the total torque ripple. The total torque ripple = (maximum torque - minimum torque) / average torque.

[0091] When i = j, T ij The sum of the torques of the DC components (i.e., the average value of the total output torque of the motor) generated by the interaction of the fundamental current and the 3rd, 5th, ..., mth harmonics with the corresponding back electromotive force components must be equal to the load torque value T of the motor. The torque consists of a DC component (average component) and an i+jth order component. L This yields the output conditional expression.

[0092] From the output condition expression, an infinite number of combinations of different current fundamental and harmonic frequencies can be calculated. Based on this, with the goal of minimizing the ripple of the shaft output torque (i.e., the resultant torque of the electromagnetic torque and the cogging torque), the optimal combination is selected. The shaft output torque is the resultant torque of the electromagnetic torque and the cogging torque, and the torque ripple is defined as: (maximum torque value - minimum torque value) / average torque value.

[0093] Reference values ​​for the fundamental and harmonic components of the current corresponding to each load torque are obtained offline and compiled into a lookup table. In the actual dual-loop control system, the actual motor speed is calculated from the signal of the Hall sensor. The error between the reference speed value (i.e., the target speed value) and the actual speed value is processed by the speed regulator. Since the output Tref of the speed regulator is different from T... L With the same units and similar values, the output T of the speed regulator ref Can replace T L As input to the lookup table.

[0094] Preferably, the bandwidth of the speed regulator is set to a low value. This allows the current reference value to be obtained.

[0095] In one embodiment, refer to Figure 3 Step S12 includes:

[0096] S121. Virtually convert the current motor current into the phase current of an m-phase motor. Where m is the highest order of the harmonics to be extracted, and m is an odd number greater than 1.

[0097] S122. Decouple the phase currents using m-phase vector space to map the fundamental wave and several harmonics to n subspaces respectively. Each subspace corresponds to either the fundamental wave or an odd-order harmonic, and n = (m+1) / 2.

[0098] Among them, the current motor current of a single-phase permanent magnet motor can be obtained by sampling through an analog-to-digital converter.

[0099] In one embodiment, step S121 includes:

[0100] For the current motor current, perform m-1 phase shifts, each phase shift causing the current motor current to lag the phase by 2π / m electrical angles to construct an m-phase motor and obtain the phase current of the m-phase motor.

[0101] Step S122 includes:

[0102] The phase current is transformed from the m-phase vector to the decoupled vector space using a transformation matrix. For the fundamental wave and harmonics below the m-2 order, there is a pair of mutually orthogonal fundamental or harmonic components on each of the two axes of the corresponding subspace. For the m-th harmonic, the m-th harmonic lies on one axis of the corresponding subspace.

[0103] In order to extract and control the fundamental wave and the odd-order current harmonics from 3 to m, the current motor current is phase-shifted m-1 times by software. Each phase shift causes the current phase to lag by 2π / m (i.e., α) electrical angles, thus constructing a virtual m-phase motor system.

[0104] The m-phase current components formed by phase shifting are decoupled into m-phase vector space by transformation matrix to obtain n subspaces, where n = (m+1) / 2.

[0105] The subspace obtained by the transformation of rows 1 and 2 of the transformation matrix is ​​the αβ subspace, to which the fundamental wave is mapped. The α and β axes contain a pair of mutually orthogonal fundamental wave components. The subspace obtained by rows 3 and 4 is the z1z2 subspace, and the subspace obtained by rows 5 and 6 is the Z3z4 subspace, and so on. The 3rd to m-2nd harmonics reside in these subspaces, with each subspace containing a pair of mutually orthogonal harmonic components on each of the two axes. The o1 subspace is obtained by the transformation of row m, with the mth harmonic located on the o1 axis. The fundamental and harmonic components of the current, a total of n components, are transformed into n subspaces.

[0106] In one embodiment, the phase current of the m-phase motor, the phase current in the decoupled vector space, and the transformation matrix are represented by the following formulas:

[0107]

[0108] [i α i β i z1 i z2 … i o1 ] T =T VSD [i1 i2 i3 … i m ] T .

[0109]

[0110] α = 2π / m.

[0111] Among them, i s Represents the motor current containing harmonics, i1...i m Let f(ωt) represent the phase current of each phase, ω represent the electrical angular frequency of the motor, t represent time, m represent the number of phases of the virtual motor, and f(ωt) represent the current motor current. VSD Represents the transformation matrix, [i α i β i z1 i z2 … i o1 ] T i represents the phase current in the decoupled vector space. α and i β i represents a pair of mutually orthogonal fundamental components in the subspace corresponding to the fundamental wave. z1 and i z2 This represents a pair of mutually orthogonal harmonic components in the subspace corresponding to the 3rd harmonic, and so on up to the (m-2)th harmonic, io1 This represents the harmonic components of the subspace corresponding to the m-th harmonic.

[0112] Wherein, by the transformation matrix T VSD The subspaces obtained from the transformations in rows 1 and 2 are called the αβ subspaces. The fundamental wave is mapped to this subspace, and the α and β axes contain a pair of mutually orthogonal fundamental wave components. The subspaces obtained from the transformations in rows 3 and 4 are called the z1z2 subspaces, the subspaces obtained from the transformations in rows 5 and 6 are called the z3z4 subspaces, and so on. The 3rd to m-2nd harmonics are located in these subspaces, and each subspace contains a pair of mutually orthogonal harmonic components on its two axes. The o1 subspace is obtained from the transformation in row m, and the mth harmonic is located on the o1 axis. The fundamental wave and its harmonics, a total of n components, are transformed into n subspaces.

[0113] In one embodiment, refer to Figure 4 In step S15, "each component difference generates a voltage reference value component through a corresponding current controller, and the sum of all voltage reference value components is used as the voltage reference value," includes:

[0114] S151. For the fundamental wave and harmonics below the m-2 order, each pair of orthogonal components mapped to the corresponding subspace is transformed to the rotating coordinate system of the corresponding frequency through the Park transformation. A pair of first DC components on the dq axis are obtained in each subspace. The difference between each first DC component and the reference value of the corresponding component is used to generate a first voltage reference value component through a PI controller.

[0115] S152. For the m-th harmonic, the AC component mapped to one axis in the corresponding subspace is used to generate a second voltage reference value component by passing the difference between the AC component and the reference value of the corresponding component through a PR controller.

[0116] S153. The α-axis component obtained after the first voltage reference value component undergoes inverse Park transformation is used as the voltage reference value, and the sum of the α-axis component and the second voltage reference value component is used as the voltage reference value.

[0117] Specifically, the fundamental wave and the pairs of orthogonal components of the 3rd to m-2th harmonics mapped to the various subspaces such as αβ, z1z2, z3z4 are transformed to a rotating coordinate system of the corresponding frequency using the Park transform. After the Park transform, a pair of DC components on the dq axis are obtained in each subspace. Each component is controlled by a PI controller, and the mth harmonic mapped to the o1 axis is controlled by a PR controller. The α-axis component obtained by the inverse Park transform of the outputs of all PI controllers is added to the output of the PR controller to serve as the voltage reference value for the motor.

[0118] The following example illustrates the application of a torque ripple suppression method for a single-phase permanent magnet motor.

[0119] A four-pole, four-slot single-phase permanent magnet synchronous motor, the inverter used to drive the single-phase permanent magnet synchronous motor is as follows: Figure 5 As shown, U dc Represents the bus voltage, C dc S represents the bus capacitance. A \S A 'and S B \S B ' represents four power switching transistors and their anti-parallel diodes, and M represents a single-phase permanent magnet synchronous motor.

[0120] The no-load back EMF waveform and FFT (Fourier Transform) result of a single-phase permanent magnet synchronous motor at 1500 rpm are as follows: Figure 7 and Figure 8 As shown.

[0121] The overall control block diagram of a single-phase permanent magnet synchronous motor is as follows: Figure 9 As shown, the control methods can all be implemented in a microcontroller (or CPU, MCU, etc.) and its peripheral circuits. The motor speed n and rotor position θ are calculated from the output of the position sensor. The error between the given speed and the actual speed is passed through a PI controller, and then the input of the aforementioned lookup table is replaced by the speed PI controller output and placed into the closed loop.

[0122] A single-phase current is obtained by sampling with an analog-to-digital converter (AD). The single-phase current is then phase-shifted four times by software. Each phase shift causes the current phase to lag by 2π / 5 electrical degrees, thus constructing a virtual five-phase motor system.

[0123] The phase current of the virtual 5-phase motor is:

[0124]

[0125] The five-phase current components generated by phase shifting are decoupled into three subspaces using a five-phase vector space. The transformation can be expressed as:

[0126] [i α i β i z1 i z2 i o1 ] T =T VSD [i1 i2 i3 i4 i5] T .

[0127] Transformation matrix T VSD for:

[0128]

[0129] Where α = 2π / 5. The subspace obtained by the transformations in rows 1 and 2 of the above equation is the αβ subspace, to which the fundamental wave is mapped. The α and β axes represent a pair of mutually orthogonal fundamental wave components. The subspace obtained by the transformations in rows 3 and 4 is the z1z2 subspace, to which the 3rd harmonic is mapped. The z1 and z2 axes represent a pair of mutually orthogonal fundamental wave components. The o1 subspace is obtained by the transformation in row 5, where the 5th harmonic lies on the o1 axis. The virtual five-phase system and current decoupling are as follows: Figure 10 and Figure 10 As shown.

[0130] The orthogonal components of the fundamental and third harmonic waves mapped into the αβ and Z1z2 subspaces are transformed into a synchronous rotating coordinate system and a third harmonic synchronous rotating coordinate system, respectively, using the Park transform. After the Park transform, a pair of DC components on the dq axes are obtained in the αβ and z1z2 subspaces. Each component is controlled by a PI controller, and the fifth harmonic wave mapped onto the o1 axis is controlled by a PR controller. The α-axis component obtained by inverse Park transforming the outputs of all PI controllers is added to the output of the PR controller to serve as the voltage reference value for the motor.

[0131] The simulation results of this example are as follows: Figures 11-16 As shown, the motor speed and load torque are set to 750 rpm and 0.3 Nm, respectively. Only the fundamental current is present for the first 0.5 seconds, and harmonic current is injected after 0.5 seconds. Figure 11 , Figure 12 , Figure 13 and Figure 14 These are the waveforms of the phase current, the fundamental wave of the phase current, the third harmonic, and the fifth harmonic, respectively, representing the reference and actual values. Figure 16 and Figure 16 The waveforms of shaft output torque, electromagnetic torque, and speed are shown. It can be seen that the harmonic current extraction and control effect is good, the system steady-state response is good, and torque pulsation and torque fluctuation are well suppressed.

[0132] Example 2

[0133] Figure 17 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 torque ripple suppression method for a single-phase permanent magnet motor described in any of the above embodiments. Figure 17 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.

[0134] like Figure 17As 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).

[0135] Bus 93 includes a data bus, an address bus, and a control bus.

[0136] 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.

[0137] 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.

[0138] The processor 91 executes various functional applications and data processing by running computer programs stored in the memory 92, such as the single-phase permanent magnet motor torque ripple suppression method provided in any of the above embodiments.

[0139] 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.

[0140] 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.

[0141] Example 3

[0142] This disclosure also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the single-phase permanent magnet motor torque ripple suppression method provided in any of the above embodiments.

[0143] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0144] Example 4

[0145] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, implements the single-phase permanent magnet motor torque ripple suppression method described in any of the preceding embodiments.

[0146] 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.

[0147] 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 method for suppressing torque ripple in a single-phase permanent magnet motor, characterized in that, The method for suppressing torque ripple in a single-phase permanent magnet motor includes: Obtain the current motor current, and obtain a lookup table of the load torque and the corresponding fundamental component and several odd-order harmonic components of the motor current; wherein, the fundamental component and the combination of harmonic components are obtained with the goal of minimizing the pulsation of the shaft output torque. Extract the fundamental and harmonic actual values ​​from the current motor current; The load torque is taken as a reference value, and the fundamental reference value and harmonic reference value are obtained based on the torque reference value and the lookup table; wherein, the torque reference value is obtained by the difference between the set speed and the actual speed through the speed regulator; The component differences between the fundamental reference value and the harmonic reference value and the corresponding actual fundamental and harmonic values ​​are obtained respectively. Each of the component differences generates a voltage reference value component through a corresponding current controller. The sum of all voltage reference value components is used as the voltage reference value, and the switching signals of the single-phase inverter power devices are controlled according to the voltage reference value. The extraction of the fundamental and harmonic actual values ​​from the current motor current includes: The current motor current is virtualized as the phase current of an m-phase motor; where m is the highest order of the harmonics to be extracted, and m is an odd number greater than 1. The phase current is decoupled by m-phase vector space to map the fundamental wave and several harmonics to n subspaces respectively; wherein, one subspace corresponds to the fundamental wave or an odd-order harmonic, and n=(m+1) / 2; The step of virtually converting the current motor current into the phase current of an m-phase motor includes: The current motor current is phase-shifted m-1 times, with each phase shift causing the current motor current to lag in phase. The electrical angle is used to construct the m-phase motor, and the phase current of the m-phase motor is obtained; The step of decoupling the phase current using m-phase vector space to map the fundamental wave and several harmonics to n subspaces includes: The phase current is transformed from the m-phase vector to the decoupled vector space by a transformation matrix; wherein, for the fundamental wave and harmonics below the m-2th order, there is a pair of mutually orthogonal fundamental wave components or harmonic components on the two axes of the corresponding subspace; for the m-th harmonic, the m-th harmonic is located on one axis of the corresponding subspace; The phase currents of the m-phase motor, the phase currents in the decoupled vector space, and the transformation matrix are expressed by the following formulas: ； ； ； ； Among them, i s Represents the motor current containing harmonics, i1…i m These represent the phase current of each phase. The angular frequency of the motor is represented by t, time is represented by m, and the number of phases of the virtual motor is represented by m. T represents the current motor current. VSD Represents the transformation matrix, i represents the phase current in the decoupled vector space. α and i β i represents a pair of mutually orthogonal fundamental components in the subspace corresponding to the fundamental wave. z1 and i z2 This represents a pair of mutually orthogonal harmonic components in the subspace corresponding to the 3rd harmonic, and so on up to the (m-2)th harmonic, i o1 This represents the harmonic components of the subspace corresponding to the m-th harmonic.

2. The method for suppressing torque ripple in a single-phase permanent magnet motor as described in claim 1, characterized in that, The method for suppressing torque ripple in a single-phase permanent magnet motor further includes: The no-load back EMF and cogging torque waveforms of the motor are obtained through electromagnetic simulation of the motor. Fourier decomposition of the no-load back EMF is performed to obtain the expression of the no-load back EMF containing the amplitude and phase information of the fundamental wave and each harmonic. By injecting several odd-order harmonics into the current to suppress torque pulsation, we obtain the current expression containing harmonics and the torque expression of the motor. The torque component generated by the interaction between the i-th harmonic of the back electromotive force and the j-th harmonic of the current is obtained based on the no-load back electromotive force expression, the current expression, and the torque expression; where i and j are both positive odd numbers. Based on the no-load back EMF expression, the current expression, the torque expression, the torque components, and the output condition expression, with the goal of minimizing the pulsation of the shaft output torque, the values ​​of the fundamental component and odd-order harmonic components of the current corresponding to each load torque are calculated and a lookup table is constructed; wherein, the output condition expression indicates that the average value of the total torque output by the motor is equal to the load torque value of the motor.

3. The method for suppressing torque ripple in a single-phase permanent magnet motor as described in claim 2, characterized in that, The following formulas express the no-load back electromotive force, the current, the torque, the torque component, and the output condition: ； ； ； ； ； The objective of minimizing the ripple of the shaft output torque is expressed as: ； Where E0 represents the no-load back electromotive force, and i represents the harmonic order of the back electromotive force. Indicates the amplitude of the permanent magnet flux harmonics. This indicates the initial phase of the back electromotive force harmonic. The electric angular frequency of the motor is represented by t, and time is represented by i. s This represents the motor current containing harmonics, Ω represents the motor's mechanical angular velocity, and T represents the motor's angular velocity. e T represents the electromagnetic torque of the motor. c T represents the cogging torque. ij T represents the torque component. ampij This represents the average value of the corresponding torque components generated by the i-th harmonic of the back electromotive force and the j-th harmonic of the current. T represents the average value of the total torque output by the motor. L This indicates the load torque value of the motor.

4. The method for suppressing torque ripple in a single-phase permanent magnet motor as described in claim 1, characterized in that, Each of the aforementioned component differences generates a voltage reference value component through a corresponding current controller, and the sum of all voltage reference value components is used as the voltage reference value, including: For the fundamental wave and harmonics below the m-2 order, each pair of orthogonal components mapped to the corresponding subspace is transformed to the corresponding frequency rotating coordinate system through Park transformation, and a pair of first DC components on the dq axis are obtained in each subspace. The difference between each first DC component and the reference value of the corresponding component is used to generate a first voltage reference value component through a PI controller. For the mth harmonic, an AC component is mapped to an axis in the corresponding subspace, and the difference between the AC component and the reference value of the corresponding component is used to generate a second voltage reference value component through a PR controller. The α-axis component obtained after the first voltage reference value component undergoes inverse Park transformation is used as the sum of the α-axis component and the second voltage reference value component as the voltage reference value.

5. 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 torque pulsation suppression method for a single-phase permanent magnet motor as described in any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the torque pulsation suppression method for a single-phase permanent magnet motor as described in any one of claims 1 to 4.

7. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the torque ripple suppression method for a single-phase permanent magnet motor as described in any one of claims 1-4.

Images