Research on position-compensation-based control strategy for permanent magnet synchronous motors

This paper proposes a new sensor signal processing technology to detect rotor position in permanent magnet synchronous motor (PMSM). This technology uses an incremental photoelectric encoder and some hardware circuit. It is easy to achieve, and it is not only apply to the traditional three-phase PMSM, but also suitable for the multi-phase symmetry or asymmetry PMSM. The calculation and theoretical analysis show that, this new sensor signal processing technology has high detection accuracy. The mentioned technology can meet the requirement of actual use when using in the experimental system. Introduction With the advantages of simple structure, high efficiency, low noise, reliable operation, wide speed range and running at very low frequencies, PMSM is widely used in AC servo system. Accurate detection of the rotor position information is the foundation of PMSM vector control [1]. Inaccurate rotor position detection can not achieve high accuracy, high dynamic response of the motor position and speed control. More seriously, it will cause the motor does not work properly, for these reasons, the position of the rotor pole permanent magnet synchronous motor precise positioning is particularly important. Multiphase PMSM is developed on the basis of three-phase PMSM, it is applied in many fields, such as aerospace, aviation, marine electric propulsion. Compared with ordinary three-phase PMSM, Multiphase PMSM have many advantages. With the increase of number of phases, the number of current harmonics minimum times increases and the amplitude of current harmonic decreases, which improve system stability and reduce torque ripple and improve motor efficiency, while it can reduce the rotor harmonic losses[2]. Structurally, it comprises two forms, namely symmetrical and asymmetrical. For asymmetric multiphase PMSM, its rotor is asymmetry in the magnetic and electrical structural, so that it is difficult to determine the rotor pole position using the general control algorithm. This paper presents the method of rotor position detection which not only applies to traditional symmetrical multiphase PMSM, but also applies to asymmetric multiphase PMSM. Common Methods of Rotor Position Detection At present, the common method of PMSM rotor position detection is generally divided into two types: detection without position sensor or with position sensor. Detection without Position Sensor. The method of detecting rotor position without sensor is a keen research direction among scholars, which is through the analysis and calculation of motor parameters, estimate the approximate position of the rotor, such as counter electromotive force method [3], high-frequency signal injection method [4], fretting rotor method [5]. These methods are excessive dependence motor parameters obviously there are many drawbacks. Detection with Position Sensor. Compared with detection without position sensor, detection rotor position by the position sensor is the most direct and effective method. Currently, there are three commonly used position sensors: Hall sensor [6], Rotary encoder [7] and Optical encoder [8]. International Conference on Advances in Mechanical Engineering and Industrial Informatics (AMEII 2015) © 2015. The authors Published by Atlantis Press 1019 Hall sensor is small, easy installation, low price and does not require mechanical coupling device. Switch hall, which generates discrete position signal, is widely used in permanent magnet brushless DC (BLDC) motor, so that it generally can not be directly used for PMSM vector control system. However, the linear Hall can provide continuous position information, but its output tends to contain a lot of harmonic, seriously affect the accuracy of the location estimation. Rotary transformer is one of detecting devices, which is commonly used to detect rotor position. Its advantage is high reliability and strong anti-jamming capability, but the rotary transformer demodulation is required, and the signal processing circuit is more complex. Optical encoder, divided into two kinds of absolute and incremental, is the most widely used method to detect the rotor position currently. The absolute encoder can directly output the absolute position of the rotor, do not need determine the rotor initial position, but the price is more expensive. The incremental photoelectric encoder with the positioning signal of U, V, W, can be used to detect the initial position of the PMSM rotor, besides it has the advantages of small size, fast response, and low price. Signal Processing Technology of the Incremental Photoelectric Encoder Incremental Photoelectric Encoder. As is shown in Figure 1, the incremental photoelectric encoder will produce three pulse signals: A, B, and Z, during the code disc rotation.

Due to the star connection of the windings, the impact of the third harmonic which does not exist in three-phase permanent magnet synchronous motor (PMSM) cannot be ignored in five-phase PMSM. So the conventional sensorless control methods for three-phase PMSM cannot be applied for five-phase PMSM directly. To achieve the sensorless control for five-phase PMSM, an iterative sliding mode observer (ISMO) is proposed with the consideration of the third harmonic impact. First, a sliding mode observer (SMO) is designed based on the fivephase PMSM model with the third harmonic to reduce the chattering and obtain the equivalent signal of the back electromotive force (EMF). Then, an adaptive back EMF observer is built to estimate the motor speed and rotor position, which eliminates the low-pass filter and phase compensation module and improves the estimation accuracy. Meanwhile, by iteratively using the SMO in one current sampling period to adjust the sliding mode gains, the sliding mode chattering and estimation errors of motor speed and rotor position are further reduced. Besides, the stability of the SMO and the adaptive back EMF observer are demonstrated in detail by Lyapunov stability criteria. Experiment results verify the effectiveness of the proposed observer for sensorless control of five-phase PMSM.

By using the observed stator voltages and currents, a method to estimate the rotor speed and position of permanent magnet synchronous motor (PMSM) based on extended Kalman filter was proposed. Then the simulations and preliminary experiment for the proposed observer of extended Kalman filter were designed and implemented. The results showed that the method can track the rotor speed and position accurately, even though the system noise and measurement noise existed in the control system. Moreover, the method is possible to estimate the speed and rotor position and implement PMSM drives without position and speed sensors.

This paper proposes a new sensorless method for estimating the mechanical speed and rotor position of the Permanent Magnet Synchronous Motor (PMSM). A voltage sensor is employed to measure the terminal voltage of the inverter. The phasor of the measured terminal voltage (phase-A) of the inverter has the same angular frequency as that of the back electro-motive force (emf) of the PMSM. Therefore, the angular frequency of the measured terminal voltage is used for computing the rotational speed of the PMSM. A simplified dynamic angle compensation term is derived that calculates the phase/angle shift between the terminal voltage phasor and the back emf phasor. The calculated phase/angle shift (angle compensation) in terms of time is then used to time-shift the terminal voltage phasor to obtain the exact rotor position of the PMSM. This proposed method does not require any complex estimation/observer based algorithm. The estimated rotor position and mechanical speed are employed for the vector control of the PMSM. A 1 kW laboratory prototype is developed and tested to assess the effectiveness of the proposed method. The proposed rotor position estimation approach is capable of estimating the rotor position with less than 1% error and consequently, tracks the reference speed with less than 0.1% steady-state error.

For position sensorless control of permanent magnet synchronous motor (PMSM), a single position estimation control algorithm is difficult to satisfy the accurate estimation of the rotor speed and position in wide speed range. In this paper, the influence of non-ideal factors such as inverter non-ideal factors, stator resistance changes on the accuracy of position estimation are analyzed. According to the analyze, the pulsating high frequency voltage injection method is more suitable for motor start and low speed range. The rotor position is estimated by the model reference adaptive system (MRAS) method in the high-speed stage. By using the combination of pulsating high frequency voltage injection method and MRAS, the position sensorless control of the PMSM from zero speed to high speed is realized. Simulation and experimental results shows that the proposed sensorless control system based on the complex algorithm has good dynamic response performance within full speed.

For permanent magnet synchronous motor (PMSM) control system based on sliding mode observer (SMO), the estimated values of the motor speed and the rotor position is always deviated because of variable of the PMSM parameters in actual operation. The existing optimization method is online parameter identification while the method increases the difficulty of motor control. The accuracy of its identification result directly affects the optimization effect. In order to optimize the observer's performance to obtain the rotor position better, in this paper, the regulator was constructed with rotor position compensation as the control target and the change rate of bus current caused by rotor position error as deviation by deducing the mathematical relationship between rotor position error and bus current of PMSM. Simulation model in MATLAB/Simulink and experiments results in dSPACE show high reliability of the new method and improvement of the motor efficiency.

A inverter-fed permanent magnet synchronous motor with a rotor position sensor and a speed sensor is used in many industrial applications as a DC-brushless motor. In this paper, a strategy which determines the rotor position and the speed of the permanent magnet synchronous motor by using the instantaneous values of phase voltage and phase current sensing is explained.In a permanent magnet synchronous motor, the permeance of the stater magnetic circuit is altered by rotating the rotor position; the inductance of a phase winding changes according to rotor positions. Hence, the phase voltages and currents of the motor have close relations with the rotor positions. Measured values of phase voltages and currents and the values of the equivalent circuit parameters are substituted to the voltage equation of the synchronous motor. Then, we can calculate the value of the rotor position angle by that voltage equation. The rotating speed of the rotor can be calculated from the voltage equation by substituting the rotor position angle. In these calculations, we used a 16-bit micro-computer and a DSP, and for sensing phase voltages and currents, 12-bit high quality A/D converters are used.Experimental results obtained by using the prototype system were congruous values of the rotor position angles and the rotating speed.

In recent years, the hairpin winding flat wire motor has received more and more attention because of its high power density and high torque, but the problem of increased AC copper loss caused by the increase of its wire diameter has restricted the use of the motor. Aiming at the problem of large AC copper loss in hairpin winding flat wire motors, this paper introduces the use of formed transposition windings into permanent magnet synchronous motors. Through analysis and comparison, the transposition bar suitable for permanent magnet synchronous motor is determined, and a method of inter-turn transposition that can improve the slot full rate of the motor is proposed. Taking a 223kW permanent magnet synchronous motor as an example, the transient field of the stator bar under 360° transposition was calculated by using the field-circuit combined three-dimensional(3-D) finite element method. By calculating the data, combined with the AC copper loss calculation method of the formed transposition winding given in the article, the distribution of the DC copper loss, eddy current copper loss and circulating copper loss of the motor is obtained. Compared with hairpin windings, the use of formed transposition windings can reduce the AC copper loss of the motor to a certain extent, the feasibility of using the formed transposition winding in the permanent magnet synchronous motor is verified.

In this paper, by measuring the phase voltages and currents of the permanent magnet synchronous motor (PMSM) drive, a neural-network-based rotor position and speed estimation method for PMSM is described. The proposed estimator includes two recurrent neural networks, one is used to estimate rotor speed and rotor position, and the other is used to estimate stator current. Through using an improved recursive prediction error algorithm, on-line adaptative estimation is realized. The simulation results show that the proposed approach gives a good estimation of rotor speed and position. Especially, the proposed approach has low sensitivity to perturbations of the mechanical parameters and torque disturbances.

Incremental encoder is commonly used for identifying the rotor position of a permanent-magnet synchronous motor (PMSM) in industrial applications. However, initial rotor position error exists when the conventional UVW algorithm is applied, thus uncertain disturbance occurs when Z-pulse correcting. In order to eliminate the preliminary identifying error and obtain the accurate rotor position immediately, a practical and efficient algorithm is proposed. In the proposed initial rotor identifying algorithm, the proper current vector is selected for each sector, and the accurate rotor position can be obtained in a movement of 60 electrical degrees in the worst case. A current loop auto-tuning method based on parameter estimation and frequency domain design is also proposed to construct a no-disturbance startup PMSM servo system for verifying the benefit of the proposed initial rotor identifying algorithm. Finally, comparative experiments between the conventional UVW algorithm and proposed initial rotor identifying algorithm in no-load and load case were conducted in TMS320F28335-based platform, which demonstrates the correctness and effectiveness of the proposed algorithms.

This study developed a realization of sensorless control for a permanent magnet synchronous motor (PMSM) using a field-programmable gate array (FPGA). Both position and speed were estimated using a high-frequency (HF) injection scheme. Accurate estimation is essential to ensure the proper functioning of sensorless motor control. To improve the estimation accuracy of the rotor position and reduce the motor speed ripple found in conventional methods, a new extraction strategy for estimating the rotor position and motor speed is proposed. First, signal modulation compensation was applied to expand the information of the error function in order to provide more accurate data to the tracking loop system for rotor position extraction. Second, to minimize the motor speed ripple caused by the HF injection, motor speed estimation was performed after obtaining the rotor position information using a differential equation with a low-pass filter (LPF) to avoid the direct effect of the injected signal. Verified experimentally, the results showed that the rotor position error did not exceed 10 el.deg, so these methods effectively reduce the rotor position estimation error by about 30%, along with the motor speed ripple. Therefore, better performance in sensorless PMSM control can be achieved in motor control applications.

Problem statement: This study investigates a novel optimized scheme of a High Frequency Signal Injection (HFSI) based sensor less technique in order to carry out a precise and robust rotor position error estimation of a Permanent Magnet Synchronous Motor (PMSM) drive designed for washing machines. The study was carried out for standstill condition, where precise position information was required for this application. Approach: In order to get rotor position error information, a PMSM high frequency model was considered in the estimated rotor reference frame (d,q). The impact of the HFSI technique parameters choice on the PMSM rotor position estimation performance was studied and experimentally tested, under various injection conditions. Results: The experimental results show that the amplitude of the high frequency current, resulting from injection, was not significant to carry out high performance rotor position estimation. In order to improve rotor position estimation performance and robustness, a modified demodulation of the high frequency current resulting from injection was proposed by using a high pass filter amplifier applied to PMSM measured currents. The novel proposed rotor position error extraction scheme was implemented on a dsPIC30F6010A and was experimentally validated on a 1kW washing salient pole PMSM. Conclusion: This study presents an improved high frequency voltage injection based sensor less control for Permanent Magnet Synchronous Motor (PMSM) designed for washing machines. The optimal parameters choice of the HFSI technique and the use of a high pass filter amplifier have allowed to take the most of the high frequency injected signal for extracting the rotor position error at standstill, compared to a conventional scheme.

This paper proposes a new compensation algorithm for position error due to an amplitude imbalance between resolver output signals. Resolvers are commonly used to obtain absolute rotor position information for motor drive systems in severe environments. However, in actual position sensing systems, rotor position error is caused by amplitude imbalance of the resolver output signals. As a result, the d- and q-axis currents of the synchronous reference frame have periodic ripples of the stator fundamental frequency in Permanent Magnet Synchronous Motor (PMSM) drives. In this paper, a new compensation algorithm to reduce the position error generated by amplitude imbalance is proposed. The proposed method does not require any additional hardware, and reduces computational time by simple integral operation according to rotor position. The effectiveness of the proposed compensation algorithm is verified through several simulations and experiments.

The paper discusses the problem of state estimation for the non-salient permanent magnet synchronous motor (PMSM) and presents a method for estimation of speed and rotor position based on a sliding mode (SM) EMF observer. The observer is developed based on the full order PMSM model in the stationary reference frame. The motor speed is a required input in the proposed observer and a speed estimate obtained from the output rotor position is used. The SM observer is analysed using Lyapunov’s theory of non-linear stability and is validated by simulations and experimental tests. The proposed method is applicable in a sensorless PMSM drive; the estimator uses only the measured motor voltages and currents and produces estimates of the speed and rotor position. The influence of the feedback gains of the SM observer is discussed. The method is relatively simple to implement, involves a reduced number of design gains, does not require correction of the rotor position and has excellent accuracy for a wide speed range and at low speed.

In recent years, the application range of electric energy in modern industry has gradually expanded. Permanent magnet synchronous motor has the characteristics of high efficiency and energy saving, and has obvious advantages in traction application. In order to achieve good vector control of permanent magnet synchronous motor in the full speed range, Research on model reference adaptive system (MRAS) and pulsating high frequency injection method to construct the permanent magnet synchronous motor vector control system, and combined with the flux weakening control algorithm to control the motor under the condition of limited inverter output, so as to realize the sensorless vector control of the motor in the full speed range. The difference between the estimated value of the algorithm and the actual value is compared on the actual experimental platform to verify the feasibility of the control algorithm. The experimental results show that, Under medium and high-speed working conditions, the motor speed and rotor position tracking accuracy of MRAS algorithm is high, and the tracking error is less than 0.01rad. The pulsating high-frequency injection method can accurately track the permanent magnet synchronous motor under low-speed working conditions, the speed error is less than 1n / R / min, and the rotor position error is less than 0.03rad. The static and dynamic performance of the control system is good, It can better deal with the sudden change of motor load. Using MRAS algorithm and pulsating high frequency injection method to control permanent magnet synchronous motor in full speed range is of great significance to improve the speed control performance of permanent magnet synchronous motor.