Research On The Sensorless Vector Control Technique Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM) has wide application in the industrywhich includes servo drive with high performance, results from advantages like smallsize, simple structure, high reliability, high power density and precision. The researchon the sensorless speed control system of PMSM has become the hot topic of modernmotor control field.As the key parameters of motor control system, the position and speed of rotor areusually detected by mechanical sensor, which installation and maintenance results inthe high cost, complexity and poor reliability of system. A number of sensorless speedcontrol methods applicable to the motor in the low and mid-high speed were given byscholars in many countries, but there’s few research on the full range of sensorlessspeed control. In order to solve this problem, this paper carried out a research into thefollowing several aspects:Firstly, this paper describes the background of the research on sensorless speedcontrol of PMSM, main sensorless speed control methods, mathematical model ofPMSM based on the principle of coordinate transformation and some commonly usedmethods of vector control based on the vector control theory.Secondly, Sliding mode variable structure control is introduced, and the slidingmode observer based on the mathematical model of PMSM is designed to detect theposition and speed of rotor, and the simulation is done. System dynamic performanceis not perfect with the motor operating at low speed, because counter electromotiveforce is small under the low speed and the establishment of a sliding hyperplane needa certain amount of time. This paper mainly studied sensorless speed control based onrotating high frequency voltage injection method, considering the high frequencysignal injection method of low speed performance is good. The weighted coefficientmethod is used to implement the compound control of PMSM, rotating high frequencyvoltage injection method is used under the low speed, with the increase of rotationalspeed the sliding mode observer is used, the simulation shows that the compoundcontrol method is feasible.Finally, control system hardware platform is set, the software of control algorithmis designed. The experiment is analyzed in the actual system with compound controlmethod, the experimental results verify the correctness and effectiveness of theproposed method.