A sensorless control system for permanent magnet synchronous motor with enhanced system robustness

Abstract

The application discloses a sensorless control system of a permanent magnet synchronous motor, which enhances system robustness, and is composed of a speed given module, a speed controller module, a compound inverter module, a Clark transformation and Park transformation module and a rotor position and speed extraction module; the rotor position and speed extraction module is composed of a parameter adaptive STA-SMO module, a back electromotive force estimation module, a rotor position extraction module and a motor parameter correction module; the parameter adaptive STA-SMO module takes the alpha-beta axis voltage, current observation error, estimated motor parameter dq axis inductance and resistance as input, and outputs estimated dq axis current; the rotor position extraction module outputs estimated rotor position angle and speed, the estimated speed is fed back to the speed controller module, and the estimated rotor position angle is fed back to the compound inverter module; the correction estimated value of the inductance and motor resistance on the dq axis is obtained through calculation and is fed back to the parameter adaptive STA-SMO to update the obtained parameters, so that the position estimation precision and speed estimation precision are improved, and the system robustness is enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of motor control, specifically permanent magnet synchronous motor control, and specifically a sensorless control system for permanent magnet synchronous motor. BACKGROUND

[0002] Permanent magnet synchronous motor has the advantages of high torque density, high efficiency, good speed regulation performance, etc., and is widely used in numerical control machine tools, electric traction drives, aerospace, national defense and military industry, etc. which have high requirements on performance and efficiency. The typical permanent magnet synchronous motor control system topology consists of an outer speed loop and an inner current loop. The speed loop calculates the current command of the current inner loop according to the speed command and the speed feedback value, so the control performance of the speed loop directly determines the speed regulation performance of the motor. However, the above control performance is heavily dependent on various parameters of the motor, so high-precision encoders are usually used to obtain the speed of the motor. Installing mechanical sensors not only increases the manufacturing cost and complexity of the system, but also reduces the operating reliability of the system under extreme conditions. In order to solve this problem, sensorless control technology is used. Sensorless control technology uses a specific algorithm to estimate the rotor position and speed by detecting relevant signals in the motor winding. This control scheme has gradually become the development trend of permanent magnet synchronous motor control systems.

[0003] According to the difference in operating speed, the sensorless control scheme can be divided into two categories: model-based method and saliency-based method: when the motor operates in the medium and high speed range, the model-based method is used, which mainly includes two schemes: back-EMF estimation and flux linkage estimation; when the motor operates at low speed or zero speed, the signal-to-noise ratio of the useful signal is very low, and it is difficult to extract, so the model-based method is not suitable for low speed, therefore, the high-frequency signal injection method is used to obtain the rotor position information.

[0004] In recent years, various model-based sensorless methods have been developed, such as model reference adaptive system, sliding mode observer and extended Kalman filter. Among them, the sliding mode observer has simple structure and strong robustness, and has been widely used in sensorless control. However, the traditional sliding mode observer has the problems of chattering and phase delay. In order to solve this problem, document 1“D. Liang, J. Li and R. Qu, “Sensorless control of permanent magnet synchronous machine based on second-order sliding-mode observer with online resistance estimation,” IEEE Trans. Ind. Appl., vol. 53, no. 4, pp. 3672-3682, July-Aug. 2017.” proposes a sliding mode observer based on super-spiral algorithm, which uses a super-torsion function instead of a sign function to effectively suppress the chattering problem. However, it only considers the change of resistance, so the position estimation is affected by the change of inductance.

[0005] Rotor position and speed information can also be extracted using a phase-locked loop. However, the traditional phase-locked loop uses a fixed gain proportional integral (PI) controller to process the position signal to obtain rotor position and speed information. Due to changes in operating conditions and motor parameters and other factors, the fixed gain PI controller cannot guarantee the expected performance. In view of these problems, document 2“C. Lascu and G. Andreescu, “PLL position and speed observer with integrated current observer for sensorless PMSM drives,” IEEE Trans. Ind. Electron., vol. 67, no. 7, pp. 5990-5999, July 2020.” proposes a five-order phase-locked loop position and speed observer based on excitation model, which is composed of a two-order phase-locked loop position observer and a three-order extended Luenberger speed observer. Experimental results show that the observer lacks good dynamic performance and robustness, and the structure is complex.

[0006] Therefore, it is necessary to provide a permanent magnet synchronous motor control system with simple structure, which can enhance the estimation accuracy and robustness to solve the above problems. SUMMARY

[0007] This invention addresses the issues of robustness and estimation accuracy in permanent magnet synchronous motors (PMSMs) by providing a sensorless control system for PMSMs that enhances system robustness. This system improves the position and velocity observation accuracy of PMSMs and features a simple structure, fast convergence speed, and good robustness, while also exhibiting better dynamic and steady-state performance.

[0008] To achieve the above objectives, the present invention provides a sensorless control system for a permanent magnet synchronous motor that enhances system robustness, employing the following technical solution: It comprises a speed setting module, a speed controller module, a composite inverter module, Clark and Park transformation modules, and a rotor position and speed extraction module; the speed setting module outputs a reference speed ω. * The speed controller module outputs the q-axis reference current. In the composite inverter module, the output three-phase current, along with the three-phase voltage, is input to the voltage u in the αβ axis obtained from the Clark and Park transformation modules. α ,u β Current i α i β and the current i in the dq axis system d i q The inputs are combined and fed into the rotor position and speed extraction module; the rotor position and speed extraction module consists of a parameter adaptive STA-SMO module, a back EMF estimation module, a rotor position extraction module, and a motor parameter correction module; the parameter adaptive STA-SMO module uses voltage u α ,u β Current observation error Motor parameter estimation values ​​for dq-axis inductance and resistance As input, output the estimated αβ axis current. Current i α i β and Current observation error obtained by subtraction As input to the back EMF estimation module, the output is the back EMF estimate. Using the estimated value of back electromotive force Motor parameter estimation values ​​for dq-axis inductance Current i d i q As input to the rotor position extraction module, the output is the estimated rotor position. and estimated rotational speed Estimated rotational speed Feedback is sent to the speed controller module to estimate the rotor position angle. Feedback is sent to the composite inverter module; using current observation error. Current and estimate the rotating speed as the input of the motor parameter correction module, the motor parameter estimated value dq-axis inductance and stator resistance is output and fed back to the parameter adaptive STA-SMO module.

[0009] further, the estimated alpha-beta axis current is: ω e is the electrical angular velocity, and Ld(k) and Lq(k) are the inductance of the d-axis and q-axis in the current control period k respectively, Rs(k) is the stator resistance in the current control period k, control law u staα ,u staβ is:

[0010]

[0011] k1 and k2 are the parameters of the sliding mode observer.

[0012] The beneficial effects of the application after adopting the above technical solutions are:

[0013] 1. In order to solve the influence of parameter change on rotor position estimation, the motor parameter adaptive STA-SMO module is designed, the correction estimated values of the inductance of the d-axis and q-axis and the motor resistance are obtained by calculation and fed back to the motor parameter adaptive STA-SMO to update the obtained parameters, the position estimation accuracy and speed estimation accuracy of the permanent magnet synchronous motor are improved, the convergence speed is fast, the robustness of the system is enhanced, and the system has better dynamic performance and steady-state performance.

[0014] 2. The control system constructed by the application has measurable and easy-to-measure control variables and input variables, the control algorithm of the system only needs to be realized by modular software programming, and additional instruments and equipment are not needed, so that the structure is simple, the control quality of the system is effectively improved without increasing the control cost, and the system is beneficial to engineering implementation. DETAILED DESCRIPTION

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used for the specific embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 is a structural block diagram of a permanent magnet synchronous motor sensorless control system for enhancing the robustness of the system.

[0017] Figure 2 For Figure 1 the constituent block diagram of the rotor position and speed extraction module 3;

[0018] Figure 3 For Figure 1 the constituent block diagram of the speed controller module 5;

[0019] Figure 4 For Figure 1 the constituent block diagram of the compound inverter module 6;

[0020] In the figure: 1. Permanent magnet synchronous motor module; 2. Clark transformation and Park transformation module; 3. Rotor position and speed extraction module; 4. Speed given module; 5. Speed controller module; 6. Compound inverter module; 31. Parameter adaptive STA-SMO module; 32. Back electromotive force estimation module; 33. Rotor position extraction module; 34. Motor parameter correction module; 51. Rotational speed decoupling module; 52. Rotational speed loop regulation module; 61. Current decoupling control module; 62. Current loop regulation module; 63. Park inverse transformation module; 64. PWM transformation module; 65. Inverter module; 66. Clark transformation module; 67. Park transformation module. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] As Figure 1 shown, the permanent magnet synchronous motor sensorless control system for enhancing system robustness of the present application is composed of a speed given module 4, a speed controller module 5, a compound inverter module 6 (i.e. PMSM1 in Figure 1 ), a Clark transformation and Park transformation module 2 and a rotor position and speed extraction module 3. The speed given module 4, the speed controller module 5, the compound inverter module 6 and the permanent magnet synchronous motor module 1 are connected in sequence, and the output of the compound inverter module 6 is fed back to the speed controller module 5 and the compound inverter module 6 through the Clark transformation and Park transformation module 2 and the rotor position and speed extraction module 3 connected in sequence. Among them, the speed given module 4 outputs the reference rotational speed ω * , which is input to the speed controller module 5, and the speed controller module 5 outputs the q-axis reference current * ​To the compound inverter module 6, the compound inverter module 6 outputs three-phase current i a , i b , i c , three-phase current i a , i b , i c and the three-phase voltage u a , u b , u c measured by the sensor are input into the Clark transformation and Park transformation module 2 together to obtain the voltage u α , u β , current i α , i β and the current i d , i q in the αβ axis system α , u β , u α , i β and the current i d , i q in the dq axis system are input into the rotor position and speed extraction module 3, wherein the Clark transformation and Park transformation module 2 obtains the voltage u α , u β by coordinate transformation, the value of which can be obtained by formula (1):

[0023]

[0024] The Clark transformation and Park transformation module 2 obtains the α and β axis currents i α , i β by coordinate transformation, the expression of which is:

[0025]

[0026] The rotor position and speed extraction module 3 outputs the estimated rotor position angle and the speed , wherein the estimated speed is fed back to the speed controller module 5, and the estimated rotor position angle is fed back to the compound inverter module 6. During the operation of the present application, the rotor position and speed extraction module 3 corrects the motor parameters in time according to the parameter changes of the motor, obtains a more accurate motor model, and further obtains a more accurate back electromotive force estimation value , so that the error is smaller, the estimation accuracy of the position sensorless control is improved, the robustness of the system is enhanced, and high-performance control of the permanent magnet synchronous motor is realized.

[0027] In combination with Figure 2As shown, the rotor position and velocity extraction module 3 consists of a parameter adaptive superhelical sliding mode observer (STA-SMO) module 31, a back electromotive force estimation module 32, a rotor position extraction module 33, and a motor parameter correction module 34. The rotor position and velocity extraction module 3 uses voltage u α ,u β Current i α i β i d i q As input, the estimated rotor position and speed This is the output.

[0028] Among them, the parameter adaptive STA-SMO module 31 uses voltage u α ,u β Current observation error Motor parameter estimation values ​​for dq-axis inductance and resistance The input is the estimated αβ-axis current, and the output is the estimated αβ-axis current. Its expression is:

[0029]

[0030] In the formula: ω e The electric angular velocity is obtained from formula (5). and These are the inductances of the d-axis and q-axis respectively for the current control cycle k, with their initial values ​​being the calibrated values ​​of the motor's d- and q-axis inductances. The stator resistance is d for the current control cycle k, with an initial value of the motor resistance calibration value. α (k),d β (k) can be obtained from formula (4):

[0031]

[0032] ω e =2πf (5)

[0033] Where f is the AC frequency of the motor system.

[0034] u staα ,u staβ The control law for the sliding mode observer is expressed as follows:

[0035]

[0036] The current observation error for the current control cycle can be obtained from formula (6). and is the current observation error of the last control period k-1, k1, k2 are the parameters of the sliding mode observer, k1 = 14, k2 = 272 respectively.

[0037]

[0038] wherein, and is the estimated αβ-axis current output by the parameter adaptive STA-SMO module 31 at the last control time.

[0039] The α and β axis currents i α , i β and the output of the parameter adaptive STA-SMO module 31 are subtracted to obtain the current observation error The current observation error is taken as the input of the back-EMF estimation module 32, and the output of the back-EMF estimation module 32 is the back-EMF estimation value The expression is:

[0040]

[0041] wherein, k1, k2 are the parameters of the sliding mode observer, k1 = 14, k2 = 272 respectively.

[0042] The back-EMF estimation value The motor parameter estimation value (detailed explanation at formula 12) and the d and q axis currents i d , i q are taken as the input of the rotor position extraction module 33, wherein the d and q axis currents i d , i q

[0043] The α and β axis currents i α , i β are obtained through park transformation, and the output of the rotor position extraction module 33 is the estimated rotor position and the estimated speed The expression is:

[0044]

[0045] In the formula: p is a differential operator, ψ f is the permanent magnet flux linkage of the motor system, and its value is ψ f = 0.0711 Wb.

[0046] In order to improve the stability of the system and the estimation accuracy of the rotor position, the current observation error The estimated αβ-axis current and the estimated speed As the input of the motor parameter correction module 34, the motor parameter estimation value is output, whose expression is:

[0047]

[0048] Wherein, L d , L q , R s are the calibration values of the motor dq-axis inductance and motor resistance.

[0049] At the same time, the motor parameter estimation value is input as the feedback value into the parameter adaptive STA-SMO module 31, for updating the parameters and reducing the error, whose expression is updated as:

[0050]

[0051] In the formula: △R s , △L d , △L q , △R s are the differences between the estimated value and the calibration value, whose expression is:

[0052]

[0053] The updated current observation value and the current value i α (k), i β (k) are subtracted to obtain the current observation error As the input of the back electromotive force estimation module 32, the output is the corrected back electromotive force estimation value, whose expression is updated as:

[0054]

[0055] The corrected back electromotive force estimation value and the dq-axis inductance estimation value and the dq-axis current i d (k), i q (k) are input into the rotor position extraction module 33, and the output is the corrected rotor position angle and speed estimation value.

[0056] As shown in Figure 3 , the speed controller module 5 is composed of the speed decoupling module 51 and the speed loop adjustment module 52. The speed controller module 5 takes the reference speed ω * output by the speed given module 4 and the estimated speed fed back by the rotor position speed extraction module 3 as the input, and outputs the q-axis reference current

[0057] First, the reference rotational speed ω output by the speed setting module 4 is... * The estimated rotational speed fed back by the rotor position and speed extraction module 3 As input, it is fed into the speed decoupling module 51 to perform speed decoupling, and the output of the speed decoupling module 51 is the error speed ω. err Its expression is:

[0058]

[0059] Then, the error speed ω err The input is fed into the speed loop adjustment module 52, and the output of the speed loop adjustment module 52 is the q-axis reference current. The output expression is:

[0060]

[0061] In the formula, K p It is the proportional gain, K i It is the integral gain.

[0062] like Figure 4 As shown, the composite inverter module 6 is composed of a current decoupling control module 61, a current loop regulation module 62, a Park inverse converter module 63, a PWM converter module 64, an inverter module 65, a Clark converter module 66, and a Park converter module 67 connected in series.

[0063] Composite inverter module 6 uses the dq axis reference current and rotor position estimate As input, three-phase electricity i a i b i c As output, the two inputs of the current decoupling control module 61 are the dq-axis reference current. These two currents The inputs are respectively the two currents i output by the Park converter module 67. d i q (With the initial value set to 0) a comparison is made, and the output of the current decoupling control module 61 is the current i in the dq coordinate system. ds and i qs The expression for the current decoupling control module 61 is:

[0064]

[0065] Current i ds i qsAs two inputs to the current loop adjustment module 62, the output of the current loop adjustment module 62 is the voltage reference value in the dq axis coordinate system. Its expression is:

[0066]

[0067] In the formula, K pd K id K represents the proportional gain and integral gain along the d-axis. qq K iq For the proportional gain and integral gain along the q-axis.

[0068] Compare the voltage reference value with the estimated rotor position angle. As the input to the Park inverse transform module 63, the output of this module is the reference voltage in the αβ axis system. Its expression is:

[0069]

[0070] The reference voltage in the αβ axis system is used as the input of the PWM converter module 64, and the output of the PWM converter module 64 is the switching signal S of the inverter. A S B S C The switch signal S A S B S C As the input to inverter module 65, the output of inverter module 65 is the three-phase current i that drives the motor to operate efficiently. a i b i c The input and output of the Clark converter module 66 are the three-phase currents i. a i b i c and the current i in the αβ axis system α i β The current i in the αβ axis system α i β As the input to the Park transformation module 67, the output of this module is the feedback current i in the dq axis coordinate system. d i q This current is input to the current decoupling control module 61.

[0071] This invention fully considers the impact of motor parameter variations on the accuracy of sensorless control. The effects of stator resistance and dq-axis inductance on the back electromotive force (EMF) estimate are calculated separately, thereby correcting the estimated back EMF and improving the accuracy of position and speed observations. By considering the variations in motor parameters, the system's robustness is also enhanced, ultimately achieving accurate position and speed estimation.

Claims

1. A sensorless control system for permanent magnet synchronous motor to enhance system robustness, characterized in that: The speed given module (4), the speed controller module (5), the compound inverter module (6), the Clark transformation and Park transformation module (2) and the rotor position and speed extraction module (3) are composed of; The speed given module (4) outputs a reference rotational speed ω * to the speed controller module (5), which outputs a q-axis reference current to the compound inverter module (6), which outputs three-phase currents, which are input together with three-phase voltages to the Clark and Park transformation module (2) to obtain the voltage u α β α β and the current i d q in the dq-axis system, which are input together to the rotor position and speed extraction module (3);​​​​ The rotor position and speed extraction module (3) is composed of a parameter adaptive STA-SMO module (31), a back electromotive force estimation module (32), a rotor position extraction module (33) and a motor parameter correction module (34); The parameter-adaptive STA-SMO module (31) takes as input the voltage u α , β , the current observation error The motor parameter estimates dq-axis inductance and resistance and outputs the estimated αβ-axis currents Current i α , β and Current observation error obtained by differencing as an input to the back EMF estimation module (32), outputting a back EMF estimate with the estimated value of back electromotive force motor parameter estimate dq-axis inductance current i d q as input to the rotor position extraction module (33), outputting an estimated rotor position and an estimated rotational speed estimated rotational speed feedback to the speed controller module (5), estimated rotor position angle feedback to the compound inverter module (6);​ current observation error current and estimated rotational speed as input to the motor parameter correction module (34), the motor parameter estimates dq-axis inductance and stator resistance are output and fed back into the parameter adaptive STA-SMO module (31).

2. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 1, characterized in that: estimated αβ-axis current is: ω e is the electrical angular velocity, and Ldand Lqare the inductances of the d-axis and q-axis, respectively, of the current in the current control period k, Rs(k) is the stator resistance in the current control period k, control law u staα u staβ is: k1, k2 are sliding mode observer parameters.

3. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 2, characterized in that: Back emf estimate is:

4. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 3, characterized in that: estimated rotor position estimated rotational speed p is a differential operator, ψ f is the permanent magnet flux linkage of the motor system.

5. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 1, characterized in that: motor parameter estimates dq-axis inductance and stator resistance respectively L d , L q , R s are the nominal values of the motor dq-axis inductance and motor resistance.

6. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 2, characterized in that: The dq-axis inductance and stator resistance are fed back into the parameter adaptive STA-SMO module (31) to update the updated current observation value as: △L d , △L q , △R s are the differences between the estimated values and the calibrated values:

7. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 6, characterized in that: updated current observation and the current i α (k), i β (k) to obtain a current observation error As an input to the back EMF estimation module (32), the output is a revised back EMF estimate, whose expression is updated to:

8. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 1, wherein: The speed controller module (5) consists of a speed decoupling module (51) and a speed loop regulation module (52), the speed controller module (5) receives as input the reference speed ω * and the estimated speed ω as output, the q-axis reference current 9. The sensorless control system of a permanent magnet synchronous motor with enhanced system robustness according to claim 8, wherein: The speed decoupling module (51) outputs an error speed The speed loop regulation module (52) outputs a q-axis reference current K p is a proportional gain, K i is an integral gain.

10. A sensorless control system for permanent magnet synchronous machines with enhanced system robustness according to any of claims 1-9, characterized in that: The composite inverter module (6) is composed of a current decoupling control module (61), a current loop regulation module (62), a Park inverse converter module (63), a PWM converter module (64), an inverter module (65), a Clark converter module (66), and a Park converter module (67) connected in series. The two inputs of the current decoupling control module (61) are the dq axis reference currents. dq axis reference current The current i in the dq coordinate system is obtained by comparing it with the two currents output by the Park transformation module (67). ds and i qs , will current i ds i qs As the input to the current loop regulation module (62), the current loop regulation module (62) outputs the voltage reference value in the dq axis coordinate system. K pd K id K represents the proportional gain and integral gain along the d-axis. qq K iq For the q-axis proportional gain and integral gain; compare the voltage reference value with the estimated rotor position angle. As the input to the Park inverse transform module (63), its output is the reference voltage in the αβ axis system. As the input of the PWM converter module (64), the PWM converter module (64) outputs a switching signal, which is used as the input of the inverter module (65). The inverter module (65) outputs three-phase current. The input and output of the Clark converter module (66) are the three-phase current and the current in the αβ axis system, respectively. The current in the αβ axis system is used as the input of the Park converter module (67), and the output is the feedback current in the dq axis coordinate system. This current is input to the current decoupling control module (61).

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