Permanent magnet synchronous motor harmonic compensation method and system considering output coupling

Abstract

The invention discloses a permanent magnet synchronous motor harmonic compensation method and system considering output coupling, and the method comprises the steps: obtaining a three-phase input current and an electrical angle of a permanent magnet synchronous motor in real time, obtaining a current component under a multi-synchronous rotating coordinate system based on the three-phase input current and the electrical angle, and obtaining a to-be-processed harmonic current component after the current component is processed; according to the motor parameters and the operation speed of the permanent magnet synchronous motor, harmonic current decoupling considering the shifting multi-reference-system rotation angle is carried out on the harmonic current component to be processed through the electrical angle, and a decoupled harmonic current component is obtained; and converting the decoupled harmonic current component into the amplitude and phase of the injection voltage for harmonic compensation, thereby compensating the compensation injection voltage into the voltage harmonic in the PMSM original controller.

Description

Technical Field

[0001] The present invention relates to the technical field of PMSM harmonic processing, and in particular to a permanent magnet synchronous motor harmonic compensation method and system considering output coupling. Background Art

[0002] Permanent magnet synchronous motor (PMSM) has the characteristics of simple structure, high power density, strong overload capacity and easy maintenance. It has been widely used in industrial robots, electric vehicles, aerospace and other fields.

[0003] The magnitude of permanent magnet synchronous motor current harmonics depends on various factors, such as inverter feed system, rectifier load system magnetic circuit saturation, manufacturing error, dead time, noise, etc. These harmonic components will produce additional losses and torque ripples in the stator winding and core of the motor, which can easily cause the motor to overheat. This phenomenon will reduce the stability and reliability of the motor operation, which is not conducive to the application of PMSM in high-precision and high-power applications.

[0004] In the prior art, most of the existing methods for removing harmonics require peripheral circuits, high current polarity detection accuracy or motor parameters, have problems of complex calculations, and cannot completely remove the harmonic problem. Summary of the invention

[0005] The object of the present invention is to provide a simple solution that can achieve harmonic compensation without any additional peripheral circuits.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a permanent magnet synchronous motor harmonic compensation method considering output coupling, including: obtaining the three-phase input current and electrical angle of the permanent magnet synchronous motor in real time, based on which, obtaining the current components in multiple synchronous rotating coordinate systems and obtaining the harmonic current components to be processed after processing; according to the motor parameters and operating speed of the permanent magnet synchronous motor, using the electrical angle, the harmonic current decoupling of the harmonic current components to be processed considering the shifted multi-reference system rotation angle is performed to obtain the decoupled harmonic current components; the decoupled harmonic current components are converted into the amplitude and phase of the injection voltage for harmonic compensation, thereby compensating the compensation injection voltage into the voltage harmonics in the original PMSM controller.

[0007] Preferably, the step of obtaining current components in multiple synchronous rotating coordinate systems and obtaining harmonic current components to be processed after processing includes: converting the three-phase input current into a first harmonic current component in multiple synchronous rotating coordinate systems; performing low-pass filtering on the first harmonic current component to obtain the harmonic current component to be processed, so as to eliminate the AC component with an average value of zero.

[0008] Preferably, the step of converting the three-phase input current into the first harmonic current component in a multiple synchronous rotating coordinate system includes: subjecting the real-time three-phase input current of the permanent magnet synchronous motor to Clark transformation and Park transformation in sequence to obtain the current component in the dq synchronous reference system; according to the current component in the dq synchronous reference system, obtaining the first harmonic current component through multiple synchronous rotating coordinate transformation processing, wherein, when the electrical angle is -6ω, the current component in the fifth-order rotating reference system is used as the first harmonic current component; when the electrical angle is 6ω, the current component in the seventh-order rotating reference system is used as the first harmonic current component.

[0009] Preferably, in the step of performing harmonic current decoupling of the harmonic current component to be processed taking into account the shifted multi-reference system rotation angle using the electrical angle according to the motor parameters and the operating speed of the permanent magnet synchronous motor to obtain the decoupled harmonic current component, the step includes: judging whether the current electrical angle of the permanent magnet synchronous motor satisfies a preset electrical angle threshold range relationship, wherein the preset electrical angle threshold range relationship is constructed according to the motor parameters and the operating speed of the permanent magnet synchronous motor, wherein, if satisfied, the current harmonic current component to be processed is converted to a pre-constructed orthogonal weak solution Decoupling is performed in a coupled coordinate system, wherein the orthogonal weak decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and the vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is equal to the q-axis inductance; if not satisfied, the current harmonic current component to be processed is converted to a pre-constructed non-orthogonal strong decoupling coordinate system for decoupling, wherein the non-orthogonal strong decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and the vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is not equal to the q-axis inductance.

[0010] Preferably, the preset electrical angle threshold range relationship is expressed by the following expression:

[0011]

[0012] λ=L q / L d

[0013] or

[0014]

[0015] Among them, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor respectively, Denotes the parameter θ5δ The threshold value, θ 5δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system, Denotes the parameter θ 7δ The threshold value, θ 7δ R represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system. s Indicates the motor stator resistance.

[0016] Preferably, the multiple synchronous rotating coordinate transformation process is implemented using the following transformation matrix:

[0017] or

[0018] in, represents the five-fold rotation coordinate transformation matrix, represents the seven-fold rotation coordinate transformation matrix, ω represents the synchronous speed of the fundamental current, and t represents time.

[0019] Preferably, in the step of converting the current harmonic current component to be processed into a pre-constructed orthogonal weak decoupling coordinate system for decoupling, it includes: when the harmonic current to be processed is a fifth harmonic current, the decoupled harmonic current component is expressed by the following expression:

[0020]

[0021]

[0022]

[0023] Among them, i d ′5, i q ′5 represents the harmonic current components of the fifth harmonic current to be processed after decoupling in the orthogonal weak decoupling coordinate system, u d5 、u q5 They represent the d-axis and q-axis components of the fifth harmonic voltage corresponding to the fifth harmonic current to be processed, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor, ω represents the synchronous speed of the fundamental current, and R s represents the stator resistance of the motor; when the harmonic current to be processed is the seventh harmonic current, the decoupled harmonic current component is expressed by the following expression:

[0024]

[0025]

[0026]

[0027] Among them, i d ′7, i q ′7 represents the decoupled harmonic current components of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system, u d7 、u q7 They respectively represent the d-axis and q-axis components of the seventh harmonic voltage corresponding to the seventh harmonic current to be processed.

[0028] Preferably, the step of converting the current harmonic current component to be processed into a pre-constructed non-orthogonal strong decoupling coordinate system for decoupling includes: when the harmonic current to be processed is a fifth harmonic current, the decoupled harmonic current component is expressed by the following expression:

[0029]

[0030]

[0031]

[0032] Among them, i d ″5, i q ″5 respectively represent the decoupled harmonic current components of the fifth harmonic current to be processed in the non-orthogonal strong decoupling coordinate system, u d5 、u q5 They represent the d-axis and q-axis components of the fifth harmonic voltage corresponding to the fifth harmonic current to be processed, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor, ω represents the synchronous speed of the fundamental current, and R s represents the motor stator resistance, θ 5δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system; when the harmonic current to be processed is the seventh harmonic current, the decoupled harmonic current component is expressed by the following expression:

[0033]

[0034]

[0035]

[0036] Among them, i d ″7, i q ″7 respectively represent the decoupled harmonic current components of the seventh harmonic current to be processed in the non-orthogonal strong decoupling coordinate system, u d7、u q7 They represent the d-axis and q-axis components of the seventh harmonic voltage corresponding to the seventh harmonic current to be processed, θ 7δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system.

[0037] Preferably, the step of converting the decoupled harmonic current component into the amplitude and phase of the injection voltage for harmonic compensation includes: subjecting the decoupled harmonic current component to low-pass filtering, PI conversion and inverse coordinate transformation in sequence to obtain the compensation injection voltage.

[0038] On the other hand, an embodiment of the present invention further provides a permanent magnet synchronous motor harmonic compensation system taking output coupling into consideration, comprising: a multiple coordinate transformation module, configured to obtain the three-phase input current and electrical angle of the permanent magnet synchronous motor in real time, based on which, current components in multiple synchronous rotating coordinate systems are obtained and processed to obtain harmonic current components to be processed; a current decoupling module, configured to perform harmonic current decoupling of the harmonic current components to be processed taking into consideration the shifted multi-reference system rotation angle according to the motor parameters and operating speed of the permanent magnet synchronous motor and using the electrical angle to obtain decoupled harmonic current components; a voltage compensation module, configured to convert the decoupled harmonic current components into the amplitude and phase of the injected voltage for harmonic compensation, thereby compensating the compensation injected voltage into the voltage harmonics in the original PMSM controller.

[0039] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0040] The present invention proposes a harmonic compensation method and system for a permanent magnet synchronous motor considering output coupling. The present invention utilizes multiple synchronous rotating coordinate system transformations to obtain the amplitude and phase angle of the fifth-order or seventh-order harmonic components of the current, and then selects the corresponding LPF filter to extract the current harmonics, and then decouples and compensates the current harmonics by establishing a shifted multi-reference system. Compared with other methods, the algorithm of the present invention is simpler. Error analysis proves that the deviation caused by the motor parameters does not affect the stability, and proposes flexible use in different situations to reduce the complexity of the calculation and obtain a faster response.

[0041] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0043] Figure 1 A schematic diagram of the steps of a permanent magnet synchronous motor harmonic compensation method considering output coupling according to an embodiment of the present application.

[0044] Figure 2 This is a schematic diagram of the implementation principle of the permanent magnet synchronous motor harmonic compensation method considering output coupling in an embodiment of the present application.

[0045] Figure 3 A schematic diagram of the principle of current decoupling in a permanent magnet synchronous motor harmonic compensation method considering output coupling according to an embodiment of the present application.

[0046] Figure 4 A module block diagram of a permanent magnet synchronous motor harmonic compensation system considering output coupling according to an embodiment of the present application. DETAILED DESCRIPTION

[0047] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0048] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be performed in a sequence different from that here.

[0049] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0050] In order to solve the technical problems in the above-mentioned background technology, the embodiment of the present application proposes a permanent magnet synchronous motor harmonic compensation method and system considering output coupling. The method and system include: measuring the electrical angle of the PMSM and the three-phase current of the PMSM, and obtaining the harmonic currents in two 5th or 7th rotating reference systems through multiple synchronous rotating coordinate system transformations, and obtaining the harmonic current components to be processed after filtering with a low-pass filter (LPF); and performing voltage compensation on the two harmonic current components to be processed using the decoupling harmonic compensation strategy of the shifted multi-reference system. The present invention does not require peripheral circuits and current polarity judgment algorithms, and the calculation is simple, the algorithm is easy to understand, and the 5th and 7th harmonics can be removed.

[0051] Figure 1 A schematic diagram of the steps of a permanent magnet synchronous motor harmonic compensation method considering output coupling according to an embodiment of the present application. Figure 2 This is a schematic diagram of the implementation principle of the permanent magnet synchronous motor harmonic compensation method considering output coupling in the embodiment of the present application. Figure 1 and Figure 2 The specific steps and implementation principles of the harmonic compensation method described in the embodiment of the present invention are explained.

[0052] Step S110, obtaining the electrical angle and three-phase input current of the permanent magnet synchronous motor in real time, and obtaining the current component in the multiple synchronous rotating coordinate systems according to the real-time electrical angle and the real-time three-phase input current, so as to obtain the harmonic current component to be processed after processing the current component converted by the rotating coordinate system.

[0053] In step S110, the real-time three-phase input current of the permanent magnet synchronous motor obtained by real-time measurement is first converted into the first harmonic current component in a multiple synchronous rotating coordinate system, and then the first harmonic current component is low-pass filtered to obtain the harmonic current component to be processed, so as to eliminate the AC component with an average value of zero.

[0054] In the process of converting the real-time three-phase input current into the first harmonic current component, firstly, the real-time three-phase input current of the permanent magnet synchronous motor measured in real time is subjected to Clark transformation and Park transformation in sequence to obtain the current component under the dq synchronous reference frame.

[0055] Specifically, in actual application, PMSM is three-phase balanced and half-wave symmetrical. Considering the dead zone voltage error, the three-phase input current is expressed as:

[0056]

[0057] Where I1, I5 and I7 represent the amplitudes of the fundamental current, fifth harmonic current and seventh harmonic current of PMSM respectively, θ1, θ5 and θ7 represent the phases of the fundamental current, fifth harmonic current and seventh harmonic current of PMSM respectively, ω represents the synchronous speed of the fundamental current, t represents the time, i a 、i b and i c Represent the three-phase input current respectively.

[0058] The real-time three-phase input current of the permanent magnet synchronous motor is transformed by Clark transformation and Park transformation to obtain the current component i in the dq synchronous reference system. d and i q :

[0059]

[0060] Among them, i d 、i q It represents the current component in the dq synchronous reference frame. Since the fundamental current is a DC quantity, the fifth and seventh harmonic currents are AC quantities with angular velocities of -6ω and 6ω respectively.

[0061] Then, according to the current component in the dq synchronous reference frame, the first harmonic current component is obtained through multiple synchronous rotating coordinate transformation processing.

[0062] In one embodiment, at the real-time electrical angle ω of the permanent magnet synchronous motor T When i is -6ω, the current component in the fifth-order rotating reference system (i.e., the fifth harmonic current) is taken as the first harmonic current component. d and i q The multi-synchronous rotating coordinate system transformation is used to transform the current component to the 5-time synchronous reference system. The quintic rotating coordinate transformation matrix is ​​expressed by the following expression:

[0063]

[0064] in, represents the multi-synchronous rotating coordinate transformation matrix, ω represents the synchronous speed (the electrical angular velocity of the fundamental current), and t represents time.

[0065] Furthermore, the current components in the five synchronous reference frames obtained after coordinate transformation are:

[0066]

[0067] in, They represent the current components in the fifth-order rotating reference frame. Since the fifth harmonic current is a DC quantity, the first and seventh components are still AC quantities.

[0068] Therefore, a low-pass filter (LPF) is used to obtain the fifth harmonic current through low-pass filtering:

[0069]

[0070] Wherein, LPF(·) represents the LPF operator, which can remove the AC component with an average value of zero; i d5 、i q5 They respectively represent the d-axis component and q-axis component of the fifth harmonic current to be processed.

[0071] In another embodiment, at the real-time electrical angle ω of the permanent magnet synchronous motor T When is 6ω, the current component in the seventh-order rotating reference system (i.e., the seventh harmonic current) is taken as the first harmonic current component. d and i q The multi-synchronous rotating coordinate system transformation is used to transform the current component to the seven-time synchronous reference system. The seven-time rotating coordinate transformation matrix is ​​expressed as follows:

[0072]

[0073] in, Represents a multiple synchronous rotation coordinate transformation matrix.

[0074] Furthermore, the current components in the seven synchronous reference frames obtained after coordinate transformation are:

[0075]

[0076] in, They represent the current components in seven times rotating reference frames respectively.

[0077] Furthermore, a low-pass filter (LPF) is used to obtain the seventh harmonic current through low-pass filtering:

[0078]

[0079] Among them, i d7 、i q7 They respectively represent the d-axis component and q-axis component of the seventh harmonic current to be processed.

[0080] After obtaining the harmonic current component to be processed, the process proceeds to step S120 to carry out harmonic current decoupling processing.

[0081] In step S120, based on the motor parameters and operating speed of the permanent magnet synchronous motor and utilizing the real-time electrical angle of the permanent magnet synchronous motor measured in real time in step S110, the harmonic current components to be processed are decoupled by taking into account the shifted multi-reference frame rotation angle to obtain the decoupled harmonic current components.

[0082] In step S120, it is necessary to determine in real time whether the electrical angle of the current permanent magnet synchronous motor satisfies a preset electrical angle threshold range relationship. In an embodiment of the present invention, the preset electrical angle threshold range relationship is constructed according to the motor parameters and operating speed of the permanent magnet synchronous motor.

[0083] If the electrical angle of the current permanent magnet synchronous motor satisfies the above-mentioned preset electrical angle threshold range relationship, the current harmonic current component to be processed is converted to a pre-constructed orthogonal weak decoupling coordinate system for decoupling, thereby forming a corresponding decoupled harmonic current component. The orthogonal weak decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and the vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is equal to the q-axis inductance.

[0084] If the electrical angle of the current permanent magnet synchronous motor does not satisfy the above-mentioned preset electrical angle threshold range relationship, the current harmonic current component to be processed is converted to a pre-constructed non-orthogonal strong decoupling coordinate system for decoupling, thereby forming a corresponding decoupled harmonic current component. The non-orthogonal strong decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and the vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is not equal to the q-axis inductance.

[0085] In the embodiment of the present invention, the above-mentioned preset electrical angle threshold range relationship is expressed by the following expression:

[0086]

[0087] λ=L q / L d (10)

[0088]

[0089]

[0090] Among them, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor respectively, Denotes the parameter θ 5δ The threshold value, θ 5δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system, Denotes the parameter θ7δ The threshold value, θ 7δ R represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system. s Indicates the motor electronic resistance.

[0091] In the first embodiment, when the harmonic current component to be processed is the fifth harmonic current component to be processed, the harmonic current decoupling process in step S120 is described.

[0092] In order to study the influence of injected voltage on harmonic current, the fifth harmonic steady-state voltage equation in the coordinate system is established:

[0093]

[0094] Among them, u d5 、u q5 They represent the d-axis and q-axis components of the fifth harmonic voltage corresponding to the fifth harmonic current to be processed, ψ f5 Represents the fifth harmonic flux.

[0095] In order to simplify expression (13), the following variables are defined:

[0096]

[0097] Then equation (13) can be rewritten as the current state equation with current as the state variable:

[0098]

[0099] Figure 3 The schematic diagram of the shifted multi-reference system and the harmonic current of the PMSM in the 5th synchronous rotating coordinate system. d5 and u q5 The fifth harmonic current increase on the fifth harmonic current vector is formed respectively and The impact trajectory C idq5 .exist Figure 3 There are three coordinate systems. The first one is based on i d is the horizontal axis, i q The vertical axis is the orthogonal fifth harmonic current coordinate system C idq5 ; The second is the d-axis component of the harmonic current increase to be processed is the horizontal axis and the q-axis component As the vertical axis, and considering that the d-axis inductance of the permanent magnet synchronous motor is equal to the q-axis inductance L d =L q The orthogonal weak decoupling coordinate system C is established under the condition of i ' dq5The third is the d-axis component of the harmonic current increase to be processed is the horizontal axis and the q-axis component As the vertical axis, and considering that the d-axis inductance of the permanent magnet synchronous motor is not equal to the q-axis inductance L d ≠L q The non-orthogonal strongly decoupled coordinate system C is established under the condition of i ″ dq5 .

[0100] Among them, the d-axis phase of the fifth harmonic current to be processed is Phase with q axis is defined as follows:

[0101]

[0102] will i d5 and i q5 Transform to the orthogonal weak decoupling coordinate system C i ' dq5 Next, we have:

[0103]

[0104] Among them, i d ′5, i q '5 respectively represent the decoupled harmonic current components of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system.

[0105] Combining expression (17) with expression (3) yields:

[0106]

[0107] Therefore, we can get d ′5 and i q ′5 and u d5 and u q5 expression:

[0108]

[0109] in, and and

[0110] Then, formula (19) can be simplified as:

[0111]

[0112] Similarly, d ′5 and i q ′5 Convert to coordinate system C i ″ dq5 Down:

[0113]

[0114] in, θ 5δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system.

[0115] Expression (21) and expression (18) can be combined into:

[0116]

[0117] Therefore, we can get d "5 and i q "5 and u d5 and u q5 expression:

[0118]

[0119] in, and and

[0120]

[0121] Then, formula (23) can be simplified as:

[0122]

[0123] Furthermore, when the electrical angle of the permanent magnet synchronous motor satisfies expression (9), the fifth harmonic current to be processed can be converted to the coordinate system C i ' dq5 When it is not satisfied, the fifth harmonic current to be processed can be converted to the coordinate system C i ' d ' q5 Down.

[0124] In the second embodiment, when the harmonic current component to be processed is the seventh harmonic current component to be processed, the harmonic current decoupling process in step S120 is described.

[0125] In order to study the influence of injected voltage on harmonic current, the seventh harmonic steady-state voltage equation in the coordinate system is established:

[0126]

[0127] Among them, u d7 、u q7 They represent the d-axis and q-axis components of the seventh harmonic voltage corresponding to the seventh harmonic current to be processed, ψ f7 Represents the seventh harmonic flux.

[0128] In order to simplify expression (25), the following variables are defined:

[0129]

[0130] Then equation (25) can be rewritten as the current state equation with current as the state variable:

[0131]

[0132] Establish the d-axis component of the harmonic current increase to be processed is the horizontal axis and the q-axis component As the vertical axis, and considering that the d-axis inductance of the permanent magnet synchronous motor is equal to the q-axis inductance L d =L q The orthogonal weak decoupling coordinate system C is established under the condition of i ' dq7 ; Establish the d-axis component of the harmonic current increase to be processed is the horizontal axis and the q-axis component As the vertical axis, and considering that the d-axis inductance of the permanent magnet synchronous motor is not equal to the q-axis inductance L d ≠L q The non-orthogonal strongly decoupled coordinate system C is established under the condition of i ″ dq7 .

[0133] Among them, the d-axis phase of the seventh harmonic current to be processed is Phase with q axis The definition of is as follows:

[0134]

[0135] will i d7 and i q7 Transform to the orthogonal weak decoupling coordinate system C i ' dq7 Next, we have:

[0136]

[0137] Among them, i d ′7, i q '7 respectively represent the decoupled harmonic current components of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system.

[0138] Combining expression (29) with expression (6) yields:

[0139]

[0140] Therefore, we can get d '7 and iq ′7 and u d7 and u q7 expression:

[0141]

[0142] in, and and

[0143]

[0144] Then, formula (31) can be simplified as:

[0145]

[0146] Similarly, d '7 and i q ′7Convert to coordinate system C i ″ dq7 Down:

[0147]

[0148] in, θ 7δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system.

[0149] Expression (33) and expression (29) can be combined into:

[0150]

[0151] Therefore, we can get d "7 and i q "7 and u d7 and u q7 expression:

[0152]

[0153] in, and and

[0154]

[0155] Then, formula (35) can be simplified as:

[0156]

[0157] Furthermore, when the electrical angle of the permanent magnet synchronous motor satisfies expression (9), the seventh harmonic current to be processed can be converted to the coordinate system C i 'dq7 When it is not satisfied, the seventh harmonic current to be processed can be converted to the coordinate system C i ' d ' q7 Down.

[0158] Step S130 converts the decoupled harmonic current component obtained in step S120 into the amplitude and phase of the injection voltage for harmonic compensation, thereby compensating the compensation injection voltage into the voltage harmonics in the original controller of the PMSM.

[0159] like Figure 2 The decoupled harmonic current component (i d ′5 and i q '5; or i d '7 and i q '7; or i d "5 and i q ″5; or d "7 and i q ″7) After low-pass filtering (LPF), PI conversion and inverse coordinate transformation, the compensation injection voltage is obtained, so that the d-axis component and q-axis component of the compensation injection voltage are respectively compensated to the corresponding voltage harmonic components in the original PMSM controller.

[0160] In one embodiment, the following reference Figure 2 , the working principle of the original PMSM controller is explained. The outer loop is the speed loop, which uses the detected speed ω r As feedback; the inner loop is the current loop, which uses current sampling to obtain the stator three-phase current i a 、i b and i c , and then through Clark transformation and Park transformation, the stator current i in the dq synchronous reference frame is obtained d and i q As feedback. Given speed ω r * and the measured speed ω r After the difference is made, the given value i of the q-axis stator current is obtained through the PI controller. q * , and the d-axis current given value i d * The given value and the measured value of the two current components are subtracted and passed through the PI controller to obtain the stator voltage u in the dq synchronous reference system. d * and u q * , two stator voltage components u d * and u q* After coupling with the compensation injection voltage of the corresponding component, the compensation of the harmonic voltage component is completed, and then the two compensated voltage components are transformed by PARK to obtain the stator voltage u in the α-β coordinate system. α and u β , which is then input into the SVPWM to obtain a three-phase duty cycle signal to control the on and off of the inverter switch tube, thereby achieving control of the PMSM.

[0161] In addition, based on the above-mentioned permanent magnet synchronous motor harmonic compensation method considering output coupling, an embodiment of the present invention further provides a permanent magnet synchronous motor harmonic compensation system considering output coupling.

[0162] Figure 4 Module block diagram of the permanent magnet synchronous motor harmonic compensation system considering output coupling according to an embodiment of the present application. Figure 4 As shown, the harmonic compensation system described in the embodiment of the present invention includes: a multiple coordinate transformation module 41, a current decoupling module 42 and a voltage compensation module 43.

[0163] Specifically, the multiple coordinate transformation module 41 is implemented according to the method described in step S110, and is configured to obtain the three-phase input current and electrical angle of the permanent magnet synchronous motor in real time, based on which, the current components in the multiple synchronous rotating coordinate systems are obtained and the harmonic current components to be processed are obtained after processing; the current decoupling module 42 is implemented according to the method described in step S120, and is configured to perform harmonic current decoupling of the harmonic current components to be processed taking into account the shifted multi-reference system rotation angle according to the motor parameters and operating speed of the permanent magnet synchronous motor and using the electrical angle to obtain the decoupled harmonic current components; the voltage compensation module 43 is implemented according to the method described in step S130, and is configured to convert the decoupled harmonic current components into the amplitude and phase of the injected voltage for harmonic compensation, thereby compensating the compensation injected voltage to the voltage harmonics in the original PMSM controller.

[0164] The present invention discloses a harmonic compensation method and system for a permanent magnet synchronous motor considering output coupling. The present invention utilizes multiple synchronous rotating coordinate system transformations to obtain the amplitude and phase angle of the fifth-order or seventh-order harmonic components of the current, and then selects the corresponding LPF filter to extract the current harmonics, and then, decoupling and compensating the current harmonics by establishing a shifted multi-reference system. Compared with other methods, the present invention has a simpler algorithm, and proves through error analysis that the deviation caused by the motor parameters does not affect the stability, and proposes flexible use in different situations to reduce the complexity of the calculation and obtain a faster response.

[0165] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0166] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0167] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0168] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0169] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0170] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A permanent magnet synchronous motor harmonic compensation method considering output coupling, characterized in that: include: The three-phase input current and electrical angle of the permanent magnet synchronous motor are obtained in real time, based on which the current components in multiple synchronous rotating coordinate systems are obtained and processed to obtain the harmonic current components to be processed; According to the motor parameters and the running speed of the permanent magnet synchronous motor, the electrical angle is used to perform harmonic current decoupling of the harmonic current component to be processed taking into account the shifted multi-reference system rotation angle, so as to obtain the decoupled harmonic current component; The decoupled harmonic current component is converted into the amplitude and phase of the injection voltage for harmonic compensation, so that the compensation injection voltage is compensated into the voltage harmonics in the original controller of the PMSM.

2. The permanent magnet synchronous motor harmonic compensation method according to claim 1, characterized in that: The step of obtaining current components in multiple synchronous rotating coordinate systems and obtaining harmonic current components to be processed after processing includes: Converting the three-phase input current into a first harmonic current component in a multiple synchronous rotating coordinate system; The first harmonic current component is subjected to low-pass filtering to obtain a harmonic current component to be processed, so as to eliminate an AC component with an average value of zero.

3. The permanent magnet synchronous motor harmonic compensation method according to claim 2, characterized in that: The step of converting the three-phase input current into a first harmonic current component in a multiple synchronous rotating coordinate system includes: The real-time three-phase input current of the permanent magnet synchronous motor is subjected to Clark transformation and Park transformation in sequence to obtain the current component in the dq synchronous reference system; According to the current component in the dq synchronous reference system, the first harmonic current component is obtained by multiple synchronous rotating coordinate transformation processing, wherein: When the electrical angle is -6ω, the current component in the fifth-order rotating reference system is used as the first harmonic current component; When the electrical angle is 6ω, the current component in the seventh-order rotating reference system is used as the first harmonic current component.

4. The permanent magnet synchronous motor harmonic compensation method according to claim 3, characterized in that: In the step of performing harmonic current decoupling of the harmonic current component to be processed taking into account the shifted multi-reference system rotation angle according to the motor parameters and the running speed of the permanent magnet synchronous motor and using the electrical angle to obtain the decoupled harmonic current component, the method comprises: It is determined whether the electrical angle of the current permanent magnet synchronous motor satisfies a preset electrical angle threshold range relationship, wherein the preset electrical angle threshold range relationship is constructed according to the motor parameters and operating speed of the permanent magnet synchronous motor, wherein: If satisfied, the current harmonic current component to be processed is converted to a pre-constructed orthogonal weak decoupling coordinate system for decoupling, wherein the orthogonal weak decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and the vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is equal to the q-axis inductance; If not satisfied, the current harmonic current component to be processed is converted to a pre-constructed non-orthogonal strong decoupling coordinate system for decoupling. The non-orthogonal strong decoupling coordinate system is established with the d-axis and q-axis components of the harmonic current increase to be processed as the horizontal axis and vertical axis respectively, and considering that the d-axis inductance of the permanent magnet synchronous motor is not equal to the q-axis inductance.

5. The permanent magnet synchronous motor harmonic compensation method according to claim 4, characterized in that: The preset electrical angle threshold range relationship is expressed by the following expression: λ=L q / L d or Among them, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor respectively, Denotes the parameter θ 5δ The threshold value, θ 5δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system, Denotes the parameter θ 7δ The threshold value, θ 7δ R represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system. s Indicates the motor stator resistance.

6. The method for harmonic compensation of a permanent magnet synchronous motor according to any one of claims 3 to 5, characterized in that: The multiple synchronous rotation coordinate transformation process is implemented using the following transformation matrix: or in, represents the five-fold rotation coordinate transformation matrix, represents the seven-fold rotation coordinate transformation matrix, ω represents the synchronous speed of the fundamental current, and t represents time.

7. The permanent magnet synchronous motor harmonic compensation method according to claim 4 or 5, characterized in that: The step of converting the harmonic current component to be processed into a pre-built orthogonal weak decoupling coordinate system for decoupling includes: When the harmonic current to be processed is the fifth harmonic current, the decoupled harmonic current component is expressed by the following expression: Among them, i d ′5, i q ′5 represents the harmonic current components of the fifth harmonic current to be processed after decoupling in the orthogonal weak decoupling coordinate system, u d5 、u q5 They represent the d-axis and q-axis components of the fifth harmonic voltage corresponding to the fifth harmonic current to be processed, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor, ω represents the synchronous speed of the fundamental current, and R s Indicates the motor stator resistance; When the harmonic current to be processed is the seventh harmonic current, the decoupled harmonic current component is expressed by the following expression: Among them, i d ′7, i q ′7 represents the decoupled harmonic current components of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system, u d7 、u q7 They respectively represent the d-axis and q-axis components of the seventh harmonic voltage corresponding to the seventh harmonic current to be processed.

8. The permanent magnet synchronous motor harmonic compensation method according to claim 4 or 5, characterized in that: The step of converting the harmonic current component to be processed into a pre-built non-orthogonal strong decoupling coordinate system for decoupling includes: When the harmonic current to be processed is the fifth harmonic current, the decoupled harmonic current component is expressed by the following expression: Among them, i d ″5、i q ″5 respectively represent the decoupled harmonic current components of the fifth harmonic current to be processed in the non-orthogonal strong decoupling coordinate system, u d5 、u q5 They represent the d-axis and q-axis components of the fifth harmonic voltage corresponding to the fifth harmonic current to be processed, L d , L q They represent the d-axis and q-axis inductances of the permanent magnet synchronous motor, ω represents the synchronous speed of the fundamental current, and R s represents the motor stator resistance, θ 5δ represents the difference between the sum of the d-axis phase and the q-axis phase of the fifth harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system; When the harmonic current to be processed is the seventh harmonic current, the decoupled harmonic current component is expressed by the following expression: Among them, i d ″7, i q ″7 respectively represent the decoupled harmonic current components of the seventh harmonic current to be processed in the non-orthogonal strong decoupling coordinate system, u d7 、u q7 They represent the d-axis and q-axis components of the seventh harmonic voltage corresponding to the seventh harmonic current to be processed, θ 7δ It represents the difference between the sum of the d-axis phase and the q-axis phase of the seventh harmonic current to be processed in the orthogonal weak decoupling coordinate system and the non-orthogonal strong decoupling coordinate system.

9. The method for harmonic compensation of a permanent magnet synchronous motor according to any one of claims 1 to 8, characterized in that: The step of converting the decoupled harmonic current component into the amplitude and phase of the injection voltage for harmonic compensation includes: The decoupled harmonic current component is subjected to low-pass filtering, PI conversion and inverse coordinate transformation in sequence to obtain the compensation injection voltage.

10. A permanent magnet synchronous motor harmonic compensation system considering output coupling, characterized in that: include: A multiple coordinate transformation module is configured to obtain the three-phase input current and electrical angle of the permanent magnet synchronous motor in real time, based on which, the current components in multiple synchronous rotating coordinate systems are obtained and processed to obtain the harmonic current components to be processed; A current decoupling module is configured to perform harmonic current decoupling of the harmonic current component to be processed by taking into account the shifted multi-reference system rotation angle according to the motor parameters and the running speed of the permanent magnet synchronous motor and using the electrical angle to obtain a decoupled harmonic current component; The voltage compensation module is configured to convert the decoupled harmonic current component into the amplitude and phase of the injection voltage for harmonic compensation, so as to compensate the compensation injection voltage into the voltage harmonics in the original controller of the PMSM.

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