Research On Position Sensorless Control Of Permanent Magnent Synchronous Motor Based On Carrier Frequency Component Method

Position sensorless control of permanent magnet synchronous motor (PMSM) is a focal point in the research domain of the high performance electric drive and control. Carrier frequency component method (CFCM) can realize position sensorless control over full speed range. In the method, the signal of the PWM inverter carrier frequency component is used as the rotor position information source. No additional injection signal is required. CFCM has become an important direction in the research of the position sensorless control. In this paper, the corresponding theory and application of the position sensorless control system for PMSM based on CFCM is studied. Major work is as following:PMSM mathematical models in common reference frames are analyzed. Two familiar carrier modes of SPWM are deeply analyzed and compared by using double Fourier transform and Bessel theory, and then the mathematical model of the inverter's output voltage is derived. The conclusion can be drawn that the modulation using three-phase triangular wave carrier can be suitable for CFCM. Mathematics models of carrier frequency component in theα-βandγ-δframes are established. According to the above analysis, the rotor position of PMSM is estimated and the results of theoretical analysis are given.The deeply analysis on parameters and inverter nonlinearity effect in the electrical machine system is studied in this paper, because of its influence in estimating the rotor position by CFCM. Firstly, the effects of estimating accuracy by the changes of motor's speed, load and motor's saliency ratio are analyzed. Secondly, carrier frequency not only affects the accuracy of rotor position's estimation, but also affects the quality of current and ripple of electromagnetic torque. So choice of carrier frequency is analyzed in this paper. Thirdly, the performance of the position sensorless control system by the influence of the nonlinearity effects is studied, based on the analysis of inverter nonlinearity effects, in the meantime, compensation strategies are proposed.For position sensorless PMSM system, identifying the initial magnetic polarity of the rotor position correctly is very important. In this paper, inductance characteristic under the action of permanent magnet magnetic motive force and the armature magnetic motive force is considered, and its Finite Element Analysis (FEA) and experiment are carried. On this basis, flux linkage and inductance mathematical models are established considering the saturation. Identification of the initial magnetic polarity is realized by using heterodyne method, utilizing the different levels of magnetic circuit saturation in the d axis. Simulation and experiment are done to test this theory. These works make effort to realize the high-performance application of position sensorless PMSM.In order to improve the system performance of dynamic response and disturbance rejection, anti-windup controllers are used to control the PMSM system. Firstly, the design of the conventional PID controller is improved aimed at the saturation phenomenon of system integral. Position sensorless control system of PMSM is designed based on an anti-windup controller and CFCM.Experimental equipment of position sensorless system for PMSM is designed. The motor system position sensorless operation is realized using the CFCM under three-phase triangular carrier modulation, and it's verified by the experiment of interior PMSM. The result indicates that this method is effective and feasible for the position sensorless control of salient synchronous motor.Theoretical analysis, simulation and experimental studies show that position sensorless synchronous motor control system based on CFCM of PWM inverter has plenty of advantages, such as the smaller sensitivity of electric parameter and the realization of system wide-speed operation, etc, which is an effective proposal to realize position sensorless motor control system.