Wide Speed Range Sensorless Control Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor (PMSM) is widely used in the filed of AC drive for itsproperty of high power density, high power factor and high efficiency. The precise information ofrotor position and speed is required in the PMSM control system, so the position sensor is installed.However the sensor not only increase the cost and volume of the system, but also limits the use ofPMSM in some extreme conditions for its property. In order to solve this problem, the sensorlesscontrol technology is introduced and become one of the hot directions of AC drive research filed.This paper start from the mathematical model of and PMSM and the principle of the Space VectorControl, select the current control strategy of id=0, and build up the simulation model. Then thesensorless control of surface mounted permanent magnet synchronous (SPMSM) is researched. Onthe basis of the full analysis of the current research status of SPMSM sensorless control, the methodof fluctuating high frequency voltage injection which applied to low and zero speed range and themethod of back electromotive force direct calculate which applied to high speed are combined torealize the sensorless control of SPMSM in wide speed range.First of all, the method of fluctuating high frequency voltage injection is researched. The principleof magnetic saturated saliency is analysed and a method of detection of magnetic saturated saliency ispresented. Then the research focus on the detection of initial position which is a special problem forthe method of fluctuating high frequency voltage injection. Based on this, a strategy of initial positiondetecting is presented. The simulation model of fluctuating high frequency voltage injection is builtand the simulation result demonstrate the feasibility of the method.Then the switch of two methods is researched, the back electromotive force extraction strategy andthe relationship between the rotor position and the back electromotive force are given. The methods ofweighted switching modes is adopted to realize smooth switching between two methods. Thesimulation model of this method is also built and the analysis is carried out.Finally, a hardware platform is designed and constructed, the idea of software and hardware designis introduced in detail, and the experimental research of both the sensor and sensorless control ofSPMSM motor is carried out. The result of experimental shows the good performance of PMSM andthe feasibility of the methods presented.