Speed Sensorless Vector Control Of Permanent Magnet Synchronous Motor (PMSM) Based On Sliding Model Observer Method

Recently, permanent magnet synchronous motors (PMSMs) are increasingly used in high performance variable speed drives for home and industrial applications. This is because the PMSM has many features, like high efficiency, compactness, high torque to inertia ratio, rapid dynamic response, simple modeling and control, and maintenance-free operation.Since the development of power semiconductor devices technology, large scale integrated circuit, microprocessor controllers and power electronic technology has been rapidly developing. This constitutes the heart of modern power electronic apparatus used in modern control system design. Presently, high power semiconductor devices are available, i.e. intelligent power module (IPM). IPM consists of high speed, low power IGBT chip. The continuing innovation in the motor control system has greatly contributed and promoting the semiconductor devices development vise visa. Therefore, Engineer designing equipment must understand the devices and their characteristic thoroughly in order to design effective, reliable, and cost-effective systems with optimum performance.The advents of modern mathematical modeling techniques (Fundamental principle of control theory), has contributed immensely in control system design, modeling and analysis which aided researcher to come out with an effective control system algorithms that meet the industrial requirement. The modern control system can yield significant gain in motor control efficiency and assuring precise control that adapts to fluctuations in system behavior in real-time.This work mainly focus on the application of speed sensorless vector control based on the sliding model observer (SMO) for permanent magnet synchronous motor (PMSM), in the application of id=0Control method, also known as field-oriented control (FOC), the amount of computational current in the algorithm is minimal, more suitable for low-level digital processing chip (DSP). This control method uses armature reaction and demagnetization effect, able to produce maximum torque, thereby increasing the efficiency of the motor (PMSM). The powering scheme was implemented through SVPWM, to supply quality power consumption pattern to drive Permanent magnetic synchronous Motor (PMSM).The essence of the sliding model observer is states (variables) reconstruction, used for estimating rotor position angle. It consists of a current model based observer and a bang-bang control generator driven by error between estimated motor currents and actual motor currents, so that when the estimated currents reach the manifold then the sliding mode occur by the bang-bang control. In order to eliminate the high frequency chattering ripples in the sliding mode observer the adoption of continuous saturation function instead of switching discontinuous function (bang-bang control).Many advantages of sensorless control such as reduced hardware complexity, low cost, reduced size, cable elimination, noise immunity, reliability and less maintenance. Never the less the key problems in sensorless vector control of ac drives is the accuracy in estimation of the stator flux vector over a wide speed range using only terminal variables (currents and voltages) and needs for sophisticated electronics (DSP). Also at start or low speed fundamental excitation is low and the observer performance tends to be poor. The reasons are the observer sensitivity to model parameter variations, nonlinearities and disturbances, limited accuracy of acquisition signals, drifts, and dc offsets, data acquisition errors, voltage distortion due to the PWM inverter and stator resistance drop which degrading the performance of sensorless drive.The proposed algorithm was modeled in the MATLAB/Simulink software with defined Permanent magnetic synchronous motor (PMSM) parameters to verify the response performance for speed sensorless vector control, which proved its dynamic responds at transient and steady state. The proposed algorithm was experimented on digital signal processor (DSP) TMS320F2808control circuit, couple with other hardware like uncontrollable controllable inverter, a Dc-bus circuit and Permanent Magnet Synchronous Motor, Exited DC motor for loading effect etc.The first chapter introduced the technical background related to control system for permanent magnet synchronous motors, the development of basic principle of sensorless vector control theory for permanent magnet synchronous motor and their significance to this research. Current research status, and points out the main key problems of speed sensorless control methods.The second chapter mainly introduces the vector control technology of permanent magnet synchronous motor, space vector modulation (SVPWM) technology, the coordinate transformation and mathematical model in voltage, current and motor torque for3phase permanent magnet synchronous provides a basis speed sensorless control.The third chapter focuses on the research of speed sensorless vector control based on sliding mode observer. This part firstly introduces the theory of sliding mode observer; simulation model is established related to the theory, and its application to permanent magnet synchronous motor. The simulation results show that, the sliding model observer for sensorless vector control has a high accuracy of motor rotor position and speed estimation at high-speed and low-speed.The fourth chapter mainly introduces the implementation and experimental verification of the speed sensorless vector control based on sliding mode observer. In this part, the system algorithm for permanent magnet synchronous motor is constructed on hardware platform, the system control software, finally the experimental verification.The last chapter is a summary, recommendation and conclusion of the thesis. The simulation and experimental results, sensorless control technique based on sliding mode observer for permanent magnet synchronous motor yield good performance, realized at high-speed, low-speed, no-load and load conditions and provides accuracy in rotor position and speed estimation. An interesting area of future research related to speed sensorless vector control for permanent magnet synchronous motor was listed. Based on the result obtained and analyzed; error free ripple, effective and low cost control method of sensorless vector control of PMSM can be achieved through sliding model observer control techniques.