A method, device, equipment and medium for controlling harmonic torque of a permanent magnet motor

Abstract

This invention provides a method, apparatus, device, and medium for harmonic torque control of a permanent magnet motor, relating to the field of harmonic control. The method includes: acquiring an initial current in a motor current control circuit, wherein the initial current includes a d-axis current and a q-axis current; pre-acquiring the maximum torque-to-current ratio curve of the motor and the amplitude and phase shift of the 5th and 7th harmonics located at the initial current; calculating the harmonic control currents corresponding to the d-axis and q-axis currents based on the amplitude, phase shift, and the maximum torque-to-current ratio curve, respectively, to generate a harmonic control command containing the harmonic control currents; and employing a harmonic current control module installed in the motor current control circuit to execute harmonic control on the initial current according to the harmonic control command, thereby suppressing the 5th and 7th harmonics and solving the problem of high system noise caused by harmonics in the motor current.

Description

Technical Field

[0001] This invention relates to the field of harmonic control, and in particular to a method, apparatus, equipment and medium for controlling the harmonic torque of a permanent magnet motor. Background Technology

[0002] During steady-state operation of a permanent magnet synchronous motor (PMSM), nonlinear characteristics such as the dead zone of the inverter switching devices, or distortions in the air gap magnetic field caused by magnetic circuit saturation effects and rotor pole structure, will all cause distortions in the motor current waveform, resulting in a series of harmonic components, including the 5th, 7th, 11th, and 13th harmonics. These harmonic current components, especially the 5th and 7th harmonics which constitute a larger proportion, will generate additional losses in the stator windings and core of the PMSM, reducing the motor's operating efficiency. When the design of an automotive PMSM results in a large harmonic torque, it can lead to significant NVH (Noise, Vibration, Harshness) noise in the drive system. Summary of the Invention

[0003] In order to overcome the above-mentioned technical defects, the purpose of this invention is to provide a method, device, equipment and medium for controlling the harmonic torque of a permanent magnet motor, which can solve the problem of large system noise caused by the 5th and 7th harmonics in the motor current.

[0004] This invention discloses a method for controlling the harmonic torque of a permanent magnet motor, comprising:

[0005] Obtain the initial current in the motor current control circuit, wherein the initial current includes the d-axis current and the q-axis current;

[0006] The maximum torque-to-current ratio curve of the motor and the amplitude and phase shift of the 5th and 7th harmonics under the initial current are obtained in advance;

[0007] Based on the amplitude, phase shift, and maximum torque-current ratio curves, calculate the harmonic control currents corresponding to the d-axis current and q-axis current, respectively, to generate harmonic control commands that include the harmonic control currents.

[0008] A harmonic current control module is used in the motor current control circuit to perform harmonic control on the initial current according to the harmonic control command, so as to suppress the 5th and 7th harmonics.

[0009] Preferably, the step of calculating the harmonic control current corresponding to the d-axis current and q-axis current based on the harmonic amplitude, phase shift, and maximum torque-current ratio curves includes:

[0010] Both the d-axis current and the q-axis current contain DC components and harmonic components.

[0011] A preset torque equation is used to establish the functional relationship between the DC component and harmonic component of the d-axis current and q-axis current and the torque based on the amplitude and phase shift of the 5th and 7th harmonics.

[0012] Under the aforementioned functional relationship, harmonic electromagnetic torque and harmonic reluctance torque in the torque are predefined respectively to obtain the expression of harmonic components in the d-axis current and q-axis current containing preset parameters.

[0013] A mapping table between the maximum torque-current ratio curve and preset parameters is generated, and preset parameters matching the DC components of the d-axis current and q-axis current are obtained from it.

[0014] The harmonic control currents corresponding to the d-axis current and q-axis current are determined based on the preset parameters and the harmonic component expression.

[0015] Preferably, the preset torque equation is expressed as:

[0016] Among them, i d =i d0 +i dh i q =i q0 +i qh ;

[0017] Where, λ d =L d i d +λ f +λ df_har ;λ q =L q i q +λ qf_har ;

[0018] Among them, i d i is the d-axis current; q This is the q-axis current;

[0019] Where P is the pole logarithm; λ f For the fundamental flux linkage of the motor; i d0 i represents the DC component of the d-axis current. dh λ represents the harmonic components in the d-axis current. df_har i represents the harmonic flux linkage corresponding to the harmonic components in the d-axis current; q0 i is the DC component of the q-axis current; qh λ represents the harmonic components in the q-axis current. qf_har This represents the harmonic flux linkage corresponding to the harmonic components in the q-axis current.

[0020] The functional relationship between the DC components and harmonic components of the d-axis and q-axis currents and the torque is expressed as follows:

[0021]

[0022] The harmonic flux linkage corresponding to the harmonic components in the d-axis current is expressed as:

[0023] λ df_har =-5k5λ f cos(6ωt+θ5)+7k7λ f cos(6ωt+θ7);

[0024] The harmonic flux linkage corresponding to the harmonic components in the q-axis current is expressed as:

[0025] λ qf_har =5k5λ f sin(6ωt+θ5)+7k7λ f sin(6ωt+θ7);

[0026] Where k5 and k7 are the scaling factors of the amplitude of the 5th and 7th harmonics to the amplitude of the fundamental wave, respectively; θ5 and θ7 are the phase shifts of the 5th and 7th harmonics, respectively.

[0027] Preferably, under the stated functional relationship, harmonic electromagnetic torque and harmonic reluctance torque in the torque are predefined to obtain expressions for harmonic components in the d-axis current and q-axis current containing preset parameters, including:

[0028] The harmonic electromagnetic torque and harmonic reluctance torque in the torque are predefined to be zero, and the initial expression is obtained.

[0029] Define θ5 and θ7 as preset values ​​to simplify the initial expression and perform trigonometric function transformation to obtain the harmonic component expressions in the d-axis current and q-axis current containing preset parameters.

[0030] Preferably, the harmonic electromagnetic torque and harmonic reluctance torque in the defined torque are both zero, expressed as:

[0031]

[0032]

[0033] Where P is the pole logarithm; λ f For the fundamental flux linkage of the motor; i d0 i represents the DC component of the d-axis current. dh λ represents the harmonic components in the d-axis current. df_har i represents the harmonic flux linkage corresponding to the harmonic components in the d-axis current; q0 i is the DC component of the q-axis current; qh λ represents the harmonic components in the q-axis current. qf_har This represents the harmonic flux linkage corresponding to the harmonic components in the q-axis current.

[0034] The initial expression is represented as:

[0035] i qh ={5k5cos(6ωt+θ5)-7k7cos(6ωt+θ7)}i q0 +{5k5sin(6ωt+θ5)+7k7sin(6ωt+θ7)}i d0 ;

[0036]

[0037] Where k5 and k7 are the scaling factors between the amplitude of the 5th and 7th harmonics and the amplitude of the fundamental wave, respectively; θ5 and θ7 are the phase shifts of the 5th and 7th harmonics, respectively.

[0038] Pre-defined θ5 and θ7 as -180 and 0 respectively, simplifying the initial expression, as follows:

[0039] i qh =(-5k5+7k7)i q0 cos(6ωt)+(-5k5-7k7)f d0 sin(6ωt);

[0040] The expression for the harmonic components in the d-axis and q-axis currents containing preset parameters is as follows:

[0041] i qh =Kcos(6ωt+Δθ);

[0042] Where K and Δθ are preset parameters.

[0043] Preferably, the harmonic current control module, which is installed in the motor current control circuit, performs harmonic control on the initial current according to the harmonic control command to suppress the 5th and 7th harmonics, including:

[0044] The harmonic current control module acquires the transformed d-axis current and q-axis current, and extracts the harmonic current signals from the d-axis current and q-axis current;

[0045] The harmonic control currents corresponding to the d-axis current and q-axis current are obtained according to the harmonic control command.

[0046] The fifth and seventh harmonics are controlled by the positive and negative 6th order transformations of the harmonic control current under the d-axis and q-axis to suppress the fifth and seventh harmonics.

[0047] Preferably, obtaining the amplitude and phase shift of the 5th and 7th harmonics includes:

[0048] Acquire the back EMF waveform data of the motor and perform signal spectrum analysis to obtain the amplitude and phase shift of the 5th and 7th harmonics.

[0049] This invention also discloses a permanent magnet motor harmonic torque control device, comprising:

[0050] An acquisition module is used to acquire the initial current in the motor current control circuit, wherein the initial current includes the d-axis current and the q-axis current;

[0051] The preprocessing module is used to pre-acquire the maximum torque-current ratio curve of the motor, as well as the amplitude and phase shift of the 5th and 7th harmonics at the initial current.

[0052] The harmonic control command calculation module is used to calculate the harmonic control current corresponding to the d-axis current and q-axis current respectively based on the amplitude, phase shift and maximum torque current ratio curve, so as to generate a harmonic control command containing the harmonic control current.

[0053] A harmonic current control module is used to be installed in the motor current control circuit to perform harmonic control on the initial current according to the harmonic control command, so as to suppress the 5th and 7th harmonics in the motor current control circuit.

[0054] The present invention also provides a computer device, the computer device comprising:

[0055] Memory, used to store executable program code; and

[0056] A processor is used to call the executable program code in the memory and execute steps including the permanent magnet motor harmonic torque control method.

[0057] The present invention also provides a computer-readable storage medium having a computer program stored thereon.

[0058] When the computer program is executed by the processor, it implements the steps of the permanent magnet motor harmonic torque control method.

[0059] Compared with existing technologies, the above technical solution has the following advantages:

[0060] The control method provided by this solution pre-stores the maximum torque-to-current ratio curve of the motor, as well as the amplitude and phase shift of the 5th and 7th harmonics. After obtaining the initial current in the motor current control circuit, the harmonic control current is pre-calculated based on the initial current outside the current control circuit. Finally, the harmonic current control module connected to the original current control circuit is used for control. The harmonic torque caused by the harmonic current due to the inverter dead zone or other reasons, or the harmonic torque caused by the motor back EMF harmonics, is injected into the motor with the corresponding harmonic current control to suppress high-frequency harmonics and solve the problem of large system noise caused by harmonics in the motor current. Attached Figure Description

[0061] Figure 1 This is a flowchart of an embodiment of the permanent magnet motor harmonic torque control method described in this invention;

[0062] Figure 2 This is a schematic diagram of the current control circuit in Embodiment 1 of the permanent magnet motor harmonic torque control method of the present invention;

[0063] Figure 3 This is a flowchart illustrating the calculation of harmonic control current in Embodiment 1 of the permanent magnet motor harmonic torque control method described in this invention;

[0064] Figure 4 This is a schematic diagram of the control circuit of the harmonic current control module in Embodiment 1 of the permanent magnet motor harmonic torque control method of the present invention;

[0065] Figure 5 The waveforms of the 5th and 7th harmonics in Embodiment 1 of the permanent magnet motor harmonic torque control method of the present invention are shown.

[0066] Figure 6 The graphs show the maximum torque-to-current ratio and the mapping relationship between torque and preset parameters in Embodiment 1 of the permanent magnet motor harmonic torque control method of the present invention.

[0067] Figure 7 The harmonic current curve controlled by the harmonic current control module in Embodiment 1 of the permanent magnet motor harmonic torque control method of the present invention;

[0068] Figure 8 This is a comparison of the harmonic current control module's current injection curves of 17.5 and 35A at 500rpm and 220N, with phases from 0 to 360 degrees, in a simulation of Embodiment 1 of the harmonic torque control method for permanent magnet motors according to the present invention.

[0069] Figure 9 This is a comparison diagram of the torque waveforms of the harmonic current control module at 500 rpm and 220 N, with and without control, in a simulation of the first embodiment of the harmonic torque control method for permanent magnet motors described in this invention.

[0070] Figure 10 This is a comparison diagram of the torque waveforms of the harmonic current control module at different speeds in the simulation of Embodiment 1 of the harmonic torque control method for permanent magnet motors described in this invention.

[0071] Figure 11 This is a schematic diagram of a module in Embodiment 2 of the permanent magnet motor harmonic torque control device of the present invention;

[0072] Figure 12 This is a schematic diagram of the structure of the computer device of the present invention.

[0073] Figure label:

[0074] 5-Permanent magnet motor harmonic torque control device; 51-Acquisition module; 52-Preprocessing module; 53-Harmonic control command calculation module; 54-Harmonic current control module; 6-Computer equipment; 61-Memory; 62-Processor. Detailed Implementation

[0075] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0076] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0077] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0078] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0079] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0080] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0081] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0082] Example 1: This example provides a method for controlling the harmonic torque of a permanent magnet motor. (See attached document.) Figure 1 , Figure 2 ,include:

[0083] S100: Obtain the initial current in the motor current control circuit, wherein the initial current includes the d-axis current and the q-axis current;

[0084] In this embodiment, a harmonic current command calculation is added to the original current control circuit to calculate the harmonic current to be controlled. A harmonic current control module is added to the original current control circuit. This module ensures that the harmonic current strictly follows the harmonic current command, controlling the harmonics and reducing the 5th and 7th harmonic currents, thus reducing torque 6th harmonic ripple. The original current control circuit includes d-axis and q-axis currents; the current obtained here is from the original current control circuit, which is the initial current mentioned above. It should be noted that both the d-axis and q-axis currents contain DC and harmonic components. In this embodiment, the calculation and control are based on the harmonic components. Furthermore, in this embodiment, harmonic current control is achieved by controlling the harmonic torque.

[0085] S200: Pre-acquire the maximum torque-to-current ratio curve of the motor, as well as the amplitude and phase shift of the 5th and 7th harmonics at the initial current;

[0086] In the above steps, the maximum torque-to-current ratio curve is the MTPA curve of the motor (see...). Figure 6 The curve is obtained directly from the database beforehand for determining the harmonic control current in subsequent step S300. The amplitude and phase shift of the 5th and 7th harmonics are used; in this embodiment, the 11th and 13th harmonics can also be used, by modifying parameters k5 and k7 to k... 11 k 13 This can be achieved by selectively adding corresponding harmonic current control modules.

[0087] Specifically, obtaining the amplitude and phase shift of the 5th and 7th harmonics includes: acquiring the back EMF waveform data of the motor and performing signal spectrum analysis to obtain the amplitude and phase shift of the 5th and 7th harmonics. In this embodiment, the back EMF waveform data of phase A motor is acquired manually, and waveform FFT analysis is performed manually (or by program execution) to extract the amplitude pu and phase shift of the 5th and 7th harmonics. That is, based on the measured FFT, k5, k7, θ5, and θ7 in the following steps can be obtained. (See also...) Figure 7 , Figure 7 The top image shows the back EMF waveform data, and the bottom image shows the actual voltage waveform reconstructed by FFT analysis. Based on this, the above amplitude and phase shift are obtained.

[0088] S300: Calculate the harmonic control current corresponding to the d-axis current and q-axis current respectively based on the amplitude, phase shift and maximum torque-current ratio curves, so as to generate a harmonic control command containing the harmonic control current;

[0089] The above steps are mainly used to set up a new harmonic current command calculation module outside the original current control circuit. This module calculates the harmonic control current, which is then injected into the motor with the corresponding harmonic current to reduce torque oscillations at the sixth harmonic frequency. Therefore, for details, please refer to... Figure 3 The step of calculating the harmonic control current corresponding to the d-axis current and q-axis current based on the harmonic amplitude, phase shift, and maximum torque-current ratio curves includes:

[0090] S310: Using a preset torque equation, establish the functional relationship between the DC component and harmonic component of the d-axis current and q-axis current and the torque based on the amplitude and phase shift of the 5th and 7th harmonics.

[0091] Specifically, the preset torque equation is expressed as follows: Where P is the pole logarithm; λ f For the fundamental magnetic flux linkage of the motor;

[0092] Among them, i d =i d0 +i dh i q =i q0 +i qh (2); This expression indicates that both the d-axis current and the q-axis current contain DC components and harmonic components; i d i is the d-axis current; q i is the q-axis current; d0 i represents the DC component of the d-axis current. dh Let i be the harmonic component in the d-axis current; where i q0 i is the DC component of the q-axis current; qh The harmonic components in the q-axis current;

[0093] Where, λd =L d i d +λ f +λ df_har ;λ q =L q i q +λ qf_har (3);

[0094] Where, λ f λ is the fundamental flux linkage of the motor; df_har λ represents the harmonic flux linkage corresponding to the harmonic components in the d-axis current. qf_har Let be the harmonic flux linkage corresponding to the harmonic components in the q-axis current.

[0095] Specifically, the harmonic flux linkage corresponding to the harmonic components in the d-axis current is expressed as:

[0096] λ df_har =-5k5λ f cos(6ωt+θ5)+7k7Lλ f cos(6ωt+θ7) (4)

[0097] The harmonic flux linkage corresponding to the harmonic components in the q-axis current is expressed as:

[0098] λ qf_har =5k5λ f sin(6ωt+θ5)+7k7λ f sin(6ωt+θ7) (5);

[0099] Where k5 and k7 are the scaling factors between the amplitude of the 5th and 7th harmonics and the amplitude of the fundamental wave, respectively; θ5 and θ7 are the phase shifts of the 5th and 7th harmonics, respectively.

[0100] Based on equations (1) to (5) above, the functional relationship between the DC component and harmonic component of the d-axis current and the q-axis current and the torque, that is, substituting equations (2) and (3) above into equation (1) above, can be expressed as:

[0101]

[0102] S320: Under the stated functional relationship, predefine the harmonic electromagnetic torque and harmonic reluctance torque in the torque to obtain the expression of harmonic components in the d-axis current and q-axis current containing preset parameters.

[0103] It should be noted that in the above formula (6), T e For torque, when substituting equations (2) and (3) into equation (1), through mathematical transformation, it is expressed as a sum of harmonic electromagnetic torque and harmonic reluctance torque, specifically, that is... Harmonic electromagnetic torque Tmag_har , Harmonic reluctance torque T rel_har Pre-define each as 0, and obtain information about i. dh i qh The calculation expression.

[0104] Specifically, under the stated functional relationship, harmonic electromagnetic torque and harmonic reluctance torque are predefined in the torque to obtain the harmonic component expressions in the d-axis current and q-axis current containing preset parameters, including:

[0105] S321: Predefine the harmonic electromagnetic torque and harmonic reluctance torque in the torque to be zero, and obtain the initial expression;

[0106] That is, the harmonic electromagnetic torque and harmonic reluctance torque in the defined torque are both zero, expressed as:

[0107]

[0108]

[0109] Where P is the pole logarithm; λ f For motor flux linkage; i d0 i represents the DC component of the d-axis current. dh λ represents the harmonic components in the d-axis current. df_har i represents the harmonic flux linkage corresponding to the harmonic components in the d-axis current; q0 The DC component of the q-axis current; 5 qh λ represents the harmonic components in the q-axis current. df_har λ represents the harmonic flux linkage corresponding to the harmonic components in the q-axis current. df_har , λ df_har Refer to equations (4) and (5) in the above steps.

[0110] The initial expression is represented as: Substituting equations (4) and (5) into the above equation, we can obtain:

[0111] i qh ={5k5cos(6ωt+θ5)-7k7cos(6ωt+λ7)}i q0 +{5k5sin(6ωt+θ5)+7k7sin(6ωt+θ7)}i d0 (7);

[0112]

[0113] S322: Define θ5 and θ7 as preset values ​​to simplify the initial expression and perform trigonometric function transformation to obtain the harmonic component expressions in the d-axis current and q-axis current containing preset parameters;

[0114] Specifically, in the above steps, θ5 and θ7 obtained from the FFT analysis are approximately 0 or ±180°. Therefore, we set θ5 = -180° and θ7 = 0 as an example to simplify the above expression. Other angles can also be obtained. Therefore, we predefine θ5 and θ7 as -180° and 0 respectively to simplify the initial expression, which is expressed as:

[0115] i qh =(-5k5+7k7)i q0 cos(6ωt)+(-5k5-7k7)i d0 sin(6ωt) (9);

[0116] After replacing the parameters with preset parameters and performing mathematical transformations, the harmonic component expressions of the d-axis current and q-axis current containing the preset parameters are expressed as follows:

[0117] i qh =Kcos(6ωt+Δθ) (10); Where K and Δθ are preset parameters.

[0118] It should be noted that the preset parameters K and Δθ here are related to i d0 i q0 Relatedly, it needs to be obtained from the maximum torque-to-current ratio curve.

[0119] S330: Generate a mapping table between the matrix and preset parameters based on the maximum torque-current ratio curve, and obtain preset parameters that match the DC components of the d-axis current and q-axis current from it;

[0120] For details, please refer to Figure 6 According to the maximum torque-to-current ratio curve (i.e., torque and i...) d The curves, torque and i q The curve graph can generate a mapping table between the matrix and preset parameters (i.e., the mapping relationship between torque and K, and the mapping relationship between torque and Δθ), according to i d0 i q0 Obtain the real-time torque corresponding to the maximum torque-current ratio curve, and then obtain the specific preset parameters of K and Δθ based on the real-time torque, which are the preset parameters that match the DC components of the d-axis current and q-axis current.

[0121] S340: Determine the harmonic control currents corresponding to the d-axis current and q-axis current based on the preset parameters that match the DC components of the d-axis current and q-axis current and the harmonic component expression.

[0122] By substituting the specific preset parameters of K and Δθ into equation (10), we can obtain i. qhThen, i is calculated according to equation (8). dh i qh i dh This refers to the harmonic control currents corresponding to the d-axis current and the q-axis current.

[0123] S400: A harmonic current control module is installed in the motor current control circuit to perform harmonic control on the initial current according to the harmonic control command, so as to suppress the 5th and 7th harmonics.

[0124] In this embodiment, refer to Figure 4 A harmonic current control module is added to the original current control module. This module is used to control the harmonic current so that it strictly follows the harmonic current command, that is, to control the circuit according to the harmonic control current calculated above.

[0125] Specifically, the harmonic current control module, which is installed in the motor current control circuit, performs harmonic control on the initial current according to the harmonic control command to suppress the 5th and 7th harmonics, including:

[0126] S410: The harmonic current control module acquires the transformed d-axis current and q-axis current, and extracts the harmonic current signals from the d-axis current and q-axis current;

[0127] The above transformations, including Park transformation, are implemented by the processing module in the original current control circuit and are also common in existing circuits, namely, extracting harmonic current signals at the error currents on the d-axis and q-axis.

[0128] S420: Obtain the harmonic control currents corresponding to the d-axis current and q-axis current according to the harmonic control command;

[0129] That is, obtain the harmonic control current calculated in step S300 above.

[0130] S430: Control the 5th and 7th harmonics by controlling the positive and negative 6th transformations according to the harmonic control current under the d-axis and q-axis, so as to suppress the 5th and 7th harmonics.

[0131] Specifically, the positive and negative 6th harmonic currents are controlled along the d-axis and q-axis respectively to control the 5th and 7th harmonic currents in the stationary coordinate system. The current undergoes a positive and negative 6th transformation along the d-axis and q-axis, passes through an LPF (low-pass filter), and then through the control module. Finally, it undergoes a negative and positive 6th transformation before outputting the controlled voltage to the d-axis and q-axis, which is then fed back into the original current control circuit. It should be noted that the 5th and 7th harmonics correspond to a positive and negative 6th transformation, while the 11th and 13th harmonics correspond to a positive and negative 12th transformation. Therefore, two harmonic current control modules can be selectively set to suppress the 5th and 7th harmonics and the 11th and 13th harmonics respectively. Setting more modules is also possible, depending on the actual application scenario and cost. See reference [link / reference needed]. Figure 7 The harmonic current control module controls only i, and does not control i. dh Control i dh and i qh The waveform diagram of the post-harmonic torque shows the control i dh and i qh The amplitude of the later harmonic is relatively small.

[0132] In this embodiment, simulation analysis is used to further demonstrate the harmonic suppression effect of the control method provided by the scheme. The simulation case uses the same motor as above. See also Figure 8 , Figure 9 and Figure 10 , Figure 8 The simulation curves show the harmonic current control module at 500 rpm and 220 N injected current of 17.5 and 35 A, with phase from 0 to 360 degrees. Figure 9 This is a comparison of the torque waveforms under simulation at 500 rpm and 220 N, with and without harmonic control (injecting harmonic control current). At 500 rpm, three scenarios were performed: no injection, injection of half the theoretical harmonic control current amplitude (17.5 A) according to the harmonic control command, and injection of the theoretical value (35 A) according to the harmonic control command. The results show that the optimal injection amplitude and phase are consistent with the theoretical value (harmonic control current). See also... Figure 10 , Figure 10 The diagram compares the torque waveforms (torque command (i.e., harmonic control command in this scheme) and the fluctuation amplitude of the 6th harmonic frequency (i.e., harmonic torque in this scheme) at different speeds. Based on the above, at four speeds (500 rpm, 1000 rpm, 1500 rpm, and 2000 rpm), this scheme uses harmonic current injection for control, compared to schemes without harmonic current injection compensation (e.g., ...). Figure 9 The torque 6th harmonic frequency fluctuation can be greatly reduced. The higher the speed, the lower the compensation effect under high torque, but a better harmonic suppression effect can be achieved.

[0133] This implementation adds a harmonic current control module to the original current control. The harmonic torque caused by harmonic current due to inverter dead zone or other reasons, or the harmonic torque caused by motor back EMF harmonics, is injected into the motor with the corresponding harmonic control current calculated based on the initial current. The harmonic current control module controls the reduction of the 5th and 7th harmonic currents, reduces the 6th harmonic frequency fluctuation of the torque, and achieves the effect of suppressing high-frequency harmonics.

[0134] Example 2: This example provides a permanent magnet motor harmonic torque control device 5, see reference. Figure 2 , Figure 4 , Figure 11 include:

[0135] The acquisition module 51 is used to acquire the initial current in the motor current control circuit, wherein the initial current includes the d-axis current and the q-axis current;

[0136] The current obtained here is the current in the original current control circuit. In this implementation, a harmonic current command calculation is added to the original current control circuit to calculate the harmonic current that needs to be controlled. A harmonic current control module is added to the original current control circuit. This module is used to control the harmonic current so that it can strictly follow the harmonic current command and perform control of the harmonics to reduce high-frequency harmonics.

[0137] Preprocessing module 52 is used to pre-acquire the maximum torque-current ratio curve of the motor and the amplitude and phase shift of the 5th and 7th harmonics under the initial current;

[0138] The maximum torque-to-current ratio curve, the amplitude and phase shift of the 5th and 7th harmonics are all obtained in advance and stored at a preset address. They are directly obtained and used for the calculation of harmonic control current during the calculation process of the harmonic control instruction calculation module 53.

[0139] The harmonic control command calculation module 53 is used to calculate the harmonic control current corresponding to the d-axis current and q-axis current respectively based on the amplitude, phase shift and maximum torque current ratio curve, so as to generate a harmonic control command containing the harmonic control current.

[0140] Specifically, the DC component and harmonic component of the d-axis current and q-axis current are obtained from the preset torque equation, and the functional relationship between them and the torque is obtained. Referring to equations (1) to (5) in Example 1, the harmonic electromagnetic torque and harmonic reluctance torque in the torque are predefined as 0, and θ5 and θ7 are preset values ​​(such as -180 and 0). The initial expression is simplified and trigonometric function transformation is performed to obtain the expressions (8) and (10) in Example 1. Finally, the preset parameters in the aforementioned expression are obtained by looking up the maximum torque-current ratio curve, and the harmonic control current is finally calculated.

[0141] The harmonic current control module 54 is configured in the motor current control circuit to perform harmonic control on the initial current according to the harmonic control command, so as to suppress the 5th and 7th harmonics in the motor current control circuit.

[0142] Specifically, harmonic current signals are extracted at the error currents on the d-axis and q-axis, which are the current signals after processing (correction or transformation) in the original circuit. The harmonic current control module is connected to the output of the error current of the original current control circuit. The harmonic current control module performs positive and negative 6 transformations according to the harmonic control command to suppress the 5th and 7th harmonics.

[0143] In this embodiment, the preprocessing module 52 stores the maximum torque-to-current ratio curve of the motor and the amplitude and phase shift of the 5th and 7th harmonics. After the acquisition module 51 acquires the initial current in the motor current control circuit, the harmonic control current is pre-calculated in the harmonic control command calculation module 53 (outside the original current control) using a preset torque formula, etc. Finally, the harmonic current control module 54, which is added on the basis of the original current control, controls the motor. The harmonic torque caused by the harmonic current due to the inverter dead zone or other reasons, or the harmonic torque caused by the motor back EMF harmonics, is injected into the motor according to the harmonic control current calculated from the initial current. This achieves suppression of high-frequency harmonics and solves the problem of large system noise caused by harmonics in the motor current.

[0144] Example 3:

[0145] To achieve the above objectives, the present invention also provides a computer device 6, which may be a smartphone, tablet computer, laptop computer, desktop computer, etc., that executes programs. Figure 12 As shown, the computer device in this embodiment includes, but is not limited to, a memory 61 and a processor 62 that can be interconnected via a device bus. It should be noted that... Figure 12 Only computer devices with components are shown; however, it should be understood that implementation of all shown components is not required, and more or fewer components may be implemented instead.

[0146] In this embodiment, memory 61 can be an internal storage unit of a computer device, such as the hard disk or RAM of the computer device. In other embodiments, memory 61 can also be an external storage device of the computer device, such as a plug-in hard disk equipped on the computer device. In this embodiment, memory 61 is typically used to store operating devices and various application software installed on the computer device, such as the program code and data (e.g., the maximum torque-to-current ratio curve and the amplitude and phase shift of the 5th and 7th harmonics at the initial current) of the permanent magnet motor harmonic torque control method in Embodiment 1. In addition, memory 61 can also be used to temporarily store various types of data that are output or to be output (e.g., harmonic control current).

[0147] In some embodiments, processor 62 may be a central processing unit (CPU), controller, microcontroller, microprocessor, or other data processing chip. This processor 62 is typically used to control the overall operation of a computer device. In this embodiment, processor 62 is used to run program code stored in memory 61 or process data, for example, to run a permanent magnet motor harmonic torque control method according to Embodiment 1.

[0148] Example 4:

[0149] To achieve the above objectives, the present invention also provides a computer-readable storage device, which includes multiple storage media, such as flash memory, hard disk, multimedia card, card-type memory (e.g., SD or D* memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, server, App application store, etc., storing computer programs thereon. When the program is executed by processor 62, it implements corresponding functions. In this embodiment, the computer-readable storage medium is used to store data, and when executed by processor 62, it implements a permanent magnet motor harmonic torque control method of Embodiment 1 and a permanent magnet motor harmonic torque control method of Embodiment 2.

[0150] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method of controlling harmonic torque in a permanent magnet electric machine, the method comprising: The method comprises: obtaining an initial current in a motor current control circuit, wherein the initial current comprises a d-axis current and a q-axis current; obtaining a maximum torque current ratio curve of the motor and amplitudes and phase shifts of 5th and 7th harmonics of the initial current; calculating harmonic control currents corresponding to the d-axis current and the q-axis current according to the amplitudes, the phase shifts and the maximum torque current ratio curve, to generate a harmonic control instruction containing the harmonic control currents; using a harmonic current control module arranged in the motor current control circuit to perform harmonic control on the initial current according to the harmonic control instruction, to suppress the 5th and 7th harmonics; wherein the calculating of the harmonic control currents corresponding to the d-axis current and the q-axis current according to the amplitudes, the phase shifts and the maximum torque current ratio curve comprises: the d-axis current and the q-axis current each contain a direct current component and a harmonic component; using a preset torque equation to establish a functional relationship between the direct current components and the harmonic components of the d-axis current and the q-axis current and torque according to the amplitudes and the phase shifts of the 5th and 7th harmonics; predefining a harmonic electromagnetic torque and a harmonic magnetic resistance torque in the torque under the functional relationship, to obtain a harmonic component expression of the d-axis current and the q-axis current containing preset parameters; generating a mapping relationship table of a matrix and the preset parameters according to the maximum torque current ratio curve, and obtaining preset parameters matched with the direct current components of the d-axis current and the q-axis current from the mapping relationship table; determining the harmonic control currents corresponding to the d-axis current and the q-axis current according to the preset parameters matched with the direct current components of the d-axis current and the q-axis current and the harmonic component expression.

2. The control method according to claim 1, wherein: The preset torque equation is expressed as: wherein ; ; wherein ; ; wherein, is the d-axis current; is the q-axis current; wherein P is the number of pole pairs; is the fundamental magnetic flux of the motor; is the direct current component in the d-axis current; is the harmonic component in the d-axis current; is the harmonic magnetic flux corresponding to the harmonic component in the d-axis current; is the direct current component in the q-axis current; is the harmonic component in the q-axis current; is the harmonic magnetic flux corresponding to the harmonic component in the q-axis current; the functional relationship between the direct current components and the harmonic components of the d-axis current and the q-axis current and torque is expressed as: ； wherein a harmonic flux corresponding to the harmonic component in the d-axis current is expressed as: ； wherein a harmonic flux corresponding to the harmonic component in the q-axis current is expressed as: ； wherein , are the proportional coefficients of the amplitudes of the 5th and 7th harmonics to the amplitude of the fundamental; , are the phase shifts of the 5th and 7th harmonics, respectively.

3. The control method according to claim 2, characterized by, the predefining of the harmonic electromagnetic torque and the harmonic magnetic resistance torque in the torque under the functional relationship, to obtain the harmonic component expression of the d-axis current and the q-axis current containing the preset parameters, comprises: the harmonic electromagnetic torque and the harmonic magnetic resistance torque in the torque are predefined as first preset values respectively, to obtain an initial expression; Definitions , respectively simplifying the initial expression with preset values and performing a trigonometric function transformation to obtain an expression of harmonic components in d-axis current and q-axis current containing preset parameters.

4. The control method according to claim 3, wherein: the harmonic electromagnetic torque and the harmonic magnetic resistance torque in the torque are defined as zero respectively, and are expressed as: ； ； wherein P is the number of pole pairs; is the fundamental wave flux of the motor; is the direct current component in the d-axis current; is the harmonic component in the d-axis current; is the harmonic flux corresponding to the harmonic component in the d-axis current; is the direct current component in the q-axis current; is the harmonic component in the q-axis current; is the harmonic flux corresponding to the harmonic component in the q-axis current; is the harmonic electromagnetic torque, is the harmonic harmonic reluctance torque; the initial expression is expressed as: ； ； wherein , are the proportional coefficients of the amplitudes of the 5th and 7th harmonics to the amplitude of the fundamental; , are the phase shifts of the 5th and 7th harmonics, respectively. predefined , Simplifying the initial expression by -180 and 0 respectively, we have: ； the obtaining of the harmonic component expression of the d-axis current and the q-axis current containing the preset parameters is expressed as: ； wherein K, is the preset parameter.

5. The control method according to claim 1, characterized by, the using of the harmonic current control module arranged in the motor current control circuit to perform the harmonic control on the initial current according to the harmonic control instruction, to suppress the 5th and 7th harmonics, comprises: the harmonic current control module obtains the transformed d-axis current and q-axis current, and extracts harmonic current signals in the d-axis current and the q-axis current; the harmonic control currents corresponding to the d-axis current and the q-axis current are obtained according to the harmonic control instruction; the 5th and 7th harmonics are controlled by controlling positive and negative 6th transformations according to the harmonic control currents in the d-axis and the q-axis, to suppress the 5th and 7th harmonics.

6. The control method according to claim 1, characterized by The amplitude and phase shift of the 5th and 7th harmonics are obtained, including: The motor back-EMF waveform data is obtained, and signal spectrum analysis is performed to obtain the amplitude and phase shift of the 5th and 7th harmonics.

7. A permanent magnet machine harmonic torque control apparatus, characterized by, Including: The initial current in the motor current control circuit is obtained by the acquisition module, wherein the initial current includes d-axis current and q-axis current; The maximum torque current ratio curve of the motor and the amplitude and phase shift of the 5th and 7th harmonics located below the initial current are obtained in advance by the preprocessing module; The harmonic control current corresponding to the d-axis current and the q-axis current is calculated according to the amplitude and phase shift and the maximum torque current ratio curve by the harmonic control instruction calculation module, to generate a harmonic control instruction containing the harmonic control current; The harmonic current control module is arranged in the motor current control circuit, and performs harmonic control on the initial current according to the harmonic control instruction, to suppress the 5th and 7th harmonics in the motor current control circuit; Wherein the harmonic control current corresponding to the d-axis current and the q-axis current is calculated according to the amplitude and phase shift and the maximum torque current ratio curve, including: The d-axis current and the q-axis current both contain direct current components and harmonic components; The function relationship between the direct current components and the harmonic components of the d-axis current and the q-axis current and the torque is established according to the amplitude and phase shift of the 5th and 7th harmonics by using a preset torque equation; The harmonic electromagnetic torque and the harmonic magnetic resistance torque in the torque are defined in advance under the function relationship, to obtain the harmonic component expression of the d-axis current and the q-axis current containing preset parameters; The mapping relationship table of the matrix and the preset parameters is generated according to the maximum torque current ratio curve, and the preset parameters matched with the direct current components of the d-axis current and the q-axis current are obtained therefrom; The harmonic control current corresponding to the d-axis current and the q-axis current is determined according to the preset parameters matched with the direct current components of the d-axis current and the q-axis current and the harmonic component expression.

8. A computer device, comprising: The computer device includes: A memory for storing executable program code; and A processor for calling the executable program code in the memory to perform the steps of the permanent magnet motor harmonic torque control method according to any one of claims 1 to 6. 9.A computer readable storage medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the steps of the permanent magnet motor harmonic torque control method according to any one of claims 1 to 6.

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