A method for suppressing current harmonics of permanent magnet synchronous motor

Abstract

A method for suppressing current harmonics of a permanent magnet synchronous motor relates to the field of permanent magnet synchronous motor control, and comprises the following steps: Step 1: designing a model reference adaptive system, including three parts: a reference model, an adjustable model and an adaptive module, to realize online identification of time-varying parameters of resistance and inductance. Step 2: designing a harmonic injection system, extracting 6x±1 times current harmonics (x is a natural number), and calculating harmonic voltage compensation. Step 3: injecting the harmonic voltage compensation calculated in step 2 into a permanent magnet synchronous motor vector control model to suppress 6x±1 times current harmonics. The present invention can identify key time-varying parameters of the harmonic injection link online during the operation of the permanent magnet synchronous motor, improve the harmonic suppression effect under time-varying motor parameters, reduce the vibration and noise of the permanent magnet synchronous motor, and realize it through software optimization, without adding additional hardware and cost, and is easy to realize.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motor current harmonic suppression strategies, and in particular relates to a permanent magnet synchronous motor current harmonic suppression method based on a model reference adaptive harmonic injection method. Background Art

[0002] Permanent magnet synchronous motors have high performance advantages and are widely used in industries such as automobiles, food processing, aerospace, textiles, chemical fibers, and military. However, due to the nonlinear characteristics of inverter power devices such as dead zone effect and conduction voltage drop, this will inevitably introduce 6x±1 current harmonics (where x is a natural number), causing 6x torque pulsation and an increase in electromagnetic force, increasing the vibration and noise of the permanent magnet synchronous motor. In addition, current harmonics will also cause additional losses and affect the efficiency of the permanent magnet synchronous motor. Therefore, the suppression of current harmonics is of great significance for exerting the performance of permanent magnet synchronous motors and reducing vibration and noise.

[0003] The existing patent search involving control strategies for suppressing current harmonics is as follows:

[0004] ① Shi Tingna from the Advanced Electrical Equipment Innovation Center of Zhejiang University applied for a method for suppressing current harmonics of a built-in permanent magnet synchronous motor, application number: CN202110797655.6, authorization announcement number: CN113507250A. ② Fan Jialun from Hefei Juyi Power System Co., Ltd. applied for a method for suppressing current harmonics of a permanent magnet synchronous motor based on improved harmonic voltage compensation, application number: CN202111174483.3, authorization announcement number: CN113890441A. ③ Liu Baoping from Wuwei Power Supply Company of State Grid Gansu Electric Power Company applied for a method for suppressing current harmonics of a permanent magnet synchronous generator based on self-disturbance rejection repetitive control, application number: CN202111263572.5, authorization announcement number: CN114123900A. ④Yao Jinguang of Shenzhen Jiemeikang Electromechanical Co., Ltd. applied for a method for suppressing current harmonics of stepper motors based on harmonic current injection method, application number: CN202110728600.X, authorization announcement number: CN113179058A. ⑤Zheng Yawei of Nanjing University of Aeronautics and Astronautics applied for a method for suppressing current harmonics of high-speed permanent magnet motors, application number: CN202110582077.4, authorization announcement number: CN113517844A. ⑥Zhai Guojian of Wuxi Lanhai Huateng Technology Co., Ltd. applied for a method for optimizing current harmonics of permanent magnet synchronous motors for new energy vehicles, application number: CN202011595547.2, authorization announcement number: CN112671293A. ⑦ Wu Zhaoqian of South China University of Technology applied for a method for suppressing motor current harmonics and torque pulsation based on order extraction, application number: CN202010359488.2, authorization announcement number: CN111464085A. ⑧ Zheng Likai of Shenzhen Faraday Electric Drive Co., Ltd. applied for a control system and method for suppressing permanent magnet synchronous motor current harmonics, application number: CN201911073675.8, authorization announcement number: CN110829903A. ⑨ Pan Zhifeng of South China University of Technology applied for an inverter current control system based on adaptive current harmonic suppression, application number: CN201911011488.7, authorization announcement number: CN110707908A. ⑩Wang Shuwang of Hefei Juyi Power System Co., Ltd. applied for a permanent magnet synchronous motor current harmonic suppression method based on harmonic injection, application number: CN201910680515.3, authorization announcement number: CN110518852A.

[0005] However, the above harmonic suppression technology still has the following problems: the harmonic suppression effect of the harmonic injection strategy is easily affected by time-varying parameters. The harmonic injection strategy generally includes harmonic identification and compensation links, and the key parameters (such as inductance, resistance, etc.) are easily affected by the complex working conditions and working environment of the permanent magnet synchronous motor and change with time, which leads to the inability of the harmonic injection strategy to achieve a good harmonic suppression effect. Therefore, it is urgent to realize parameter identification in the harmonic injection strategy.

[0006] Harmonic suppression method considering the influence of time-varying parameters of the motor, the relevant patent search is as follows: Xu Jiaqun of Beijing University of Technology applied for a motor control method with strong robustness and low current harmonics, application number: CN202111194717.0, authorization announcement number: CN114070147A.

[0007] This invention does not rely on motor parameters, which helps to improve the harmonic suppression effect under time-varying motor parameters. However, parameters such as the resonance bandwidth and resonance coefficient in this method are easily affected by multiple factors such as filtering effect, system stability, and convergence speed, and the parameters are difficult to set quickly and accurately. Summary of the invention

[0008] In view of the problem that the harmonic suppression effect of the existing harmonic injection strategy is easily affected by time-varying parameters, the purpose of the present invention is to provide a control method that can identify time-varying parameters online to improve the harmonic injection effect. The main functions that can be achieved include: 1) This method can identify key time-varying parameters of the harmonic injection link online during the operation of the permanent magnet synchronous motor, such as resistance and inductance, to improve the harmonic suppression effect under time-varying motor parameters; 2) By injecting 6x±1 current harmonics, 6x torque pulsation is suppressed, thereby reducing the vibration and noise of the permanent magnet synchronous motor. This method is implemented through software optimization, without adding additional hardware and cost, and is easy to implement.

[0009] The present invention proposes a method for suppressing current harmonics of a permanent magnet synchronous motor, which comprises the following steps:

[0010] Step 1: Design a model reference adaptive system, including a reference model, an adjustable model, and an adaptive module, to achieve online identification of time-varying parameter resistance and inductance.

[0011] Step 2: Design a harmonic injection system, extract 6x±1 current harmonics (x is a natural number), and calculate the harmonic voltage compensation amount.

[0012] Step 3: Inject the harmonic voltage compensation calculated in step 2 into the permanent magnet synchronous motor vector control model to suppress the 6x±1 current harmonics.

[0013] The specific operations of step 1 are as follows:

[0014] Step 1.1: Design the reference model of the model reference adaptive system. The voltage equation of the permanent magnet synchronous motor in the rotor synchronous coordinate system is used as the reference model. For the surface mounted permanent magnet synchronous motor, the d-axis and q-axis inductances are the same, and the reference model can be expressed as equation (1).

[0015]

[0016] In the formula, id 、i q is the d-axis or q-axis current (A); R is the stator resistance (Ω); L is the d-axis or q-axis inductance (H); ω is the electrical angular velocity (rad / s); ψ f is the permanent magnet flux (Wb); u d 、u q is the d and q axis voltage (V).

[0017] Step 1.2: Design an adjustable model of the model reference adaptive system. The adjustable model contains the stator resistance R * and d-axis or q-axis inductance L * The expression of , let:

[0018]

[0019] In the formula, i' d 、i' q 、u' d 、u' q is the intermediate variable, R * , L * are the parameters to be identified: stator resistance and d-axis or q-axis inductance.

[0020] Substituting equation (2) into equation (1) and transforming it, we get the adjustable model, as shown in equation (3).

[0021]

[0022] Step 1.3: Design the adaptive module of the model reference adaptive system. According to Popov hyperstability theory and normal dynamic system theory, the adaptive rate expression containing the parameters to be identified is obtained, as shown in formula (4).

[0023]

[0024] In the formula, is the estimated value of resistance, is the estimated value of the d-axis or q-axis inductance, K P1 , K P2 , K I1 , K I2 are the proportional and integral coefficients, and is the intermediate variable i' d and i' q An estimated value of and are the initial values ​​of stator resistance and inductance, which are known quantities.

[0025] The reciprocal of equation (2) in equation (4) is taken to obtain the real-time identification value of the inductance, which is L*; the real-time identification value of the resistance is obtained by dividing equation (1) by equation (2) in equation (4).

[0026] The specific operation of step 2 is as follows:

[0027] Step 2.1: Extract 6x±1 harmonics. The 6x±1 harmonic components of the stator three-phase current in the ABC coordinate system are converted to the dq coordinate system through coordinate transformation. This harmonic component will become a DC component, and other harmonics remain as AC components. The 6x±1 current harmonics can be extracted through a low-pass filter, and the extracted current is recorded as i d(6x±1)th and i q(6x±1)th .

[0028] Step 2.2: Calculate the harmonic voltage compensation. Use the harmonic voltage stabilization equation to calculate the harmonic voltage compensation component u of the 6x±1 harmonic. d(6x±1)th and u q(6x±1)th , the harmonic voltage regulation equation is shown in equation (5). The resistance R* and inductance L* values ​​obtained by online identification of the model reference adaptive system in step 1 are used to update the resistance and inductance in real time when calculating the compensation amount, that is, the two parameters in equation (5).

[0029]

[0030] In the formula, u d(6x±1)th and u q(6x±1)th It is the 6x±1 harmonic voltage compensation in the dq coordinate system.

[0031] Step 2.3: Calculate the total voltage compensation. Substitute the voltage compensation u obtained in step 2.2 into d(6x±1)th and u q(6x±1)th , are transformed into the α-β coordinate system through Park coordinate transformation, and they are summed to obtain the total voltage compensation u α and u β .

[0032] The specific operations of step 3 are as follows:

[0033] The total voltage compensation u after coordinate transformation in step 2 α and u β , injected into the α-β axis voltage of the permanent magnet synchronous motor vector control model (the permanent magnet synchronous motor vector control model is based on i d =0 is the overall control strategy) to achieve the suppression of 6x±1th current harmonics.

[0034] The control method of the permanent magnet synchronous motor current harmonic suppression strategy based on model reference adaptive harmonic injection of the present invention can take into account the influence of time-varying parameter resistance and inductance on harmonic injection, effectively suppress 6x±1th current harmonics, and reduce the 6xth output torque pulsation of the permanent magnet synchronous motor. At the same time, the method does not need to add additional hardware equipment, saves costs and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0036] Figure 1 It is a flow chart of the method for suppressing current harmonics of a permanent magnet synchronous motor based on model reference adaptive harmonic injection proposed in the present invention;

[0037] Figure 2 It is the basic structure of the model reference adaptive system in the method proposed in the present invention;

[0038] Figure 3 It is the basic structure and process of the harmonic injection link in the method proposed by the present invention;

[0039] Figure 4 It is the model reference adaptive harmonic injection permanent magnet synchronous motor control model proposed by the present invention;

[0040] Figure 5 It is the model reference adaptive system following the d and q axis currents;

[0041] Figure 6 It is the identification result of the resistance and inductance by the model reference adaptive system;

[0042] Figure 7 A comparison of harmonic content and harmonic distortion is made between a traditional harmonic injection strategy without a harmonic injection strategy and a traditional harmonic injection strategy without adding a model reference adaptive system in step 1 and the harmonic injection strategy of the invention. DETAILED DESCRIPTION

[0043] The present invention proposes a method for suppressing current harmonics of a permanent magnet synchronous motor based on model reference adaptive harmonic injection. The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] Taking a surface-mounted permanent magnet synchronous motor as an example, the process of harmonic injection using the control strategy of the present invention is described in detail. Figure 1 The figure shows a flow chart of a method for suppressing current harmonics of a permanent magnet synchronous motor based on model reference adaptive harmonic injection proposed by the present invention; the specific steps are as follows:

[0045] Step 1: Design a model reference adaptive system, including reference model, adjustable model and adaptive module, to achieve online identification of time-varying parameter resistance and inductance. Figure 2 .

[0046] Step 1.1: Design the reference model of the model reference adaptive system. The voltage equation of the permanent magnet synchronous motor in the rotor synchronous coordinate system is used as the reference model. Matlab & Simulink software is used for simulation. For the surface-mounted permanent magnet synchronous motor of the embodiment, the d-axis and q-axis inductances are the same. The d-axis and q-axis inductances L in this embodiment are 0.00525H, the stator resistance R is 0.958Ω, and the permanent magnet flux ψ f The reference model can be expressed as formula (A1).

[0047]

[0048] In the formula, i d 、i q is the d and q axis current (A); ω is the electrical angular velocity (rad / s); u d 、u q is the d and q axis voltage (V).

[0049] Step 1.2: Design an adjustable model of the model reference adaptive system. The adjustable model contains the stator resistance R * and inductor L * The expression of , let:

[0050]

[0051] In the formula, i' d 、i' q 、u' d 、u' q is the intermediate variable, R * , L * are the stator resistance and inductance values ​​of the parameters to be identified.

[0052] Substituting equation (2) into equation (1) and transforming it, we get the adjustable model, as shown in equation (A3).

[0053]

[0054] Step 1.3: Design the adaptive module of the model reference adaptive system. According to Popov hyperstability theory and normal dynamic system theory, the adaptive rate expression containing the parameters to be identified is obtained, as shown in formula (A4).

[0055]

[0056] In the formula, is the estimated value of resistance, is the estimated value of inductance, K P1 , K P2 , K I1 , K I2 are the proportional and integral coefficients, and is the intermediate variable i' d and i' q The estimated value of .

[0057] The reciprocal of equation (2) in equation (4) is taken to obtain the real-time identification value of the inductance, which is L*; the real-time identification value of the resistance is obtained by dividing equation (1) by equation (2) in equation (4).

[0058] Step 2: Design a harmonic injection system, extract 6x±1 current harmonics (x=1, 2) mainly 5th, 7th, 11th, and 13th, and calculate the 5th, 7th, 11th, and 13th harmonic voltage compensation. The implementation process of the harmonic injection system (i.e., harmonic injection strategy) is as follows: Figure 3 (a) shown.

[0059] Step 2.1: Extract the 5th, 7th, 11th, and 13th harmonics. The 5th, 7th, 11th, and 13th harmonics of the stator three-phase current in the ABC coordinate system are converted to the dq coordinate system through coordinate transformation. The harmonics will become DC components, and the other harmonics will remain as AC components. The 5th, 7th, 11th, and 13th current harmonics can be extracted through a low-pass filter. The extracted current is recorded as i d5th 、i d7th 、i d11th 、i d13th and i q5th 、i q7th 、i q11th 、i q13th , see Figure 3 (b).

[0060] Step 2.2: Calculate the harmonic voltage compensation. Use the harmonic voltage stabilization equation to calculate the harmonic voltage compensation components u of the 5th, 7th, 11th, and 13th harmonics. d5th 、u d7th 、u d11th 、u d13th and u q5th 、u q7th 、u q11th 、u q13th , the harmonic voltage regulation equation is shown in equation (A5). The resistance R* and inductance L* values ​​obtained by online identification of the model reference adaptive system in step 1 are used to update the resistance and inductance in real time during the compensation calculation, i.e., the two parameters in equation (A5). The implementation process and principle are shown in Figure 3 (c).

[0061]

[0062] In the formula, u d(6x±1)th and u q(6x±1)th is the harmonic voltage compensation component (x=1, 2).

[0063] Step 2.3: Calculate the total voltage compensation. Substitute the harmonic voltage compensation u obtained in step 2.2 into d5th 、u d7th 、u d11th 、u d13th and u q5th 、u q7th 、u q11th 、u q13th , are transformed into the α-β coordinate system through Park coordinate transformation, and they are summed to obtain the total voltage compensation u α and u β .

[0064] Step 3: The total voltage compensation u after coordinate transformation in step 2 α and u β , injected into the α-β axis voltage of the permanent magnet synchronous motor vector control model (the permanent magnet synchronous motor vector control model is based on i d =0 is the overall control strategy) to achieve the suppression of the 5th, 7th, 11th and 13th current harmonics.

[0065] The permanent magnet synchronous motor current harmonic suppression method described in this embodiment is a permanent magnet synchronous motor current harmonic suppression method based on model reference adaptive harmonic injection, which is applied to a motor control model to form a motor control model based on a model reference adaptive harmonic injection strategy. Figure 4 .

[0066] During the simulation process, the model reference adaptive system reference model output reference current in step 1, and the adjustable model output identification current, Figure 5 It is the following effect of the identification current of the model reference adaptive system on the reference current. The error is small and the following effect is good. Figure 6 It is the identification result of the resistance and inductance by the adaptive module of the model reference adaptive system. After adding a 3N·m load at 0.2s, the system can still maintain a good parameter identification effect.

[0067] The motor control model without harmonic injection is established in Matlab & Simulink software; the motor control model without adding the traditional harmonic injection strategy of step 1 is simulated and compared with the motor control model based on the model reference adaptive harmonic injection strategy of this embodiment, and the motor parameters (resistance, inductance, flux linkage, etc.) and operating conditions (rated speed 2000r / min) of the three models are the same. Figure 7The low-order harmonic current content and total harmonic distortion of the three control models are compared to verify the suppression effect of the present invention on current harmonics. Compared with the 5th, 7th, 11th, and 13th current harmonic content and harmonic distortion under the non-harmonic suppression strategy, the reduction is: 88.09%, 93.83%, 55.17%, 35.43%, and 38.00%; compared with the 5th, 7th, 11th, and 13th current harmonic content and harmonic distortion under the traditional harmonic injection strategy, the reduction is: 63.79%, 85.58%, 38.95%, 16.33%, and 5.63%. It proves that the harmonic injection strategy proposed by the present invention has a better harmonic suppression effect because it takes into account the influence of time-varying parameters.

Claims

1. A method for suppressing current harmonics of a permanent magnet synchronous motor, characterized in that The following steps are involved: Step 1: Design a model reference adaptive system, including a reference model, an adjustable model, and an adaptive module, to achieve online identification of time-varying parameter resistance and inductance; Step 1.1: Design a reference model for the model-referenced adaptive system The voltage equation of the permanent magnet synchronous motor in the rotor synchronous coordinate system is used as the reference model; for the surface mounted permanent magnet synchronous motor, the d-axis and q-axis inductances are the same, and the reference model is expressed as formula (1): In the formula, i d 、i q is the d-axis or q-axis current; R is the stator resistance; L is the d-axis or q-axis inductance; ω is the electrical angular velocity; ψ f is the permanent magnet flux; u d 、u q is the d and q axis voltage; Step 1.2: Design an adjustable model for the model-referenced adaptive system The adjustable model contains the stator resistance R * and d-axis or q-axis inductance L * The expression of , let: In the formula, i' d 、i' q 、u' d 、u' q is the intermediate variable, R * , L * are the parameters to be identified: stator resistance and d-axis or q-axis inductance; Substituting formula (2) into formula (1) and transforming it, we get the adjustable model, as shown in formula (3). Step 1.3: Design the adaptive module of the model reference adaptive system According to Popov's hyperstability theory and normal dynamic system theory, the adaptive rate expression containing the parameters to be identified is obtained, as shown in formula (4): In the formula, is the estimated value of resistance, is the estimated value of the d-axis or q-axis inductance, K P1 , K P2 , K I1 , K I2 are the proportional and integral coefficients, and is the intermediate variable i' d and i' q An estimated value of and are the initial values ​​of stator resistance and inductance; The reciprocal of equation (2) in equation (4) is taken to obtain the real-time identification value of the inductance, which is L*; the real-time identification value of the resistance is obtained by dividing equation (1) by equation (2) in equation (4) to obtain R*; Step 2: Design a harmonic injection system, extract 6x±1 current harmonics, where x is a natural number, and calculate the harmonic voltage compensation amount; Step 2.1: Extract 6x ± 1 harmonics The 6x±1 harmonic components of the stator three-phase current in the ABC coordinate system are converted to the dq coordinate system through coordinate transformation. The harmonic components will become DC components. The 6x±1 current harmonics are extracted through a low-pass filter and the extracted current is recorded as i d(6x±1)th and i q(6x±1)th ; Step 2.2: Calculate the harmonic voltage compensation The harmonic voltage compensation component u of 6x±1 harmonics is calculated using the harmonic voltage stabilization equation. d(6x±1)th and u q(6x±1)th , the harmonic voltage regulation equation is shown in equation (5); the resistance R* and inductance L* values ​​obtained by online identification of the model reference adaptive system in step 1 are used to update the resistance and inductance in real time during the compensation calculation; In the formula, u d(6x±1)th and u q(6x±1)th is the 6x±1 harmonic voltage compensation in the dq coordinate system; Step 2.3: Calculate the total voltage compensation The voltage compensation u obtained in step 2.2 d(6x±1)th and u q(6x±1)th , are transformed into the α-β coordinate system through Park coordinate transformation, and they are summed to obtain the total voltage compensation u α and u β ; Step 3: Inject the harmonic voltage compensation calculated in step 2 into the permanent magnet synchronous motor vector control model to suppress the 6x±1 current harmonics.

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