Speed Sensorless Control Of Pmsm Based On Dual Ekf And Signal Injection Method

There are many speed estimation algorithms based on the motor mathematical model for the speed sensroless control of PMSM(Permanent Magnet Synchronous Motor),such as sliding mode observer,EKF algorithm,etc.;however,when the motor runs at low speed,the back EMF is small and difficult to detect,so it is hard to get accurate speed information based on the motor's model.At this time,the signal injection method is applied to the speed sensorless control of PMSM at low speed.Because it is independent to the motor's model and parameters.Therefore,different estimation algorithms are considered in different speed areas for the whole speed range sensorless control.Because the electrical parameters such as stator resistance,q-axis inductance and rotor flux influences the performance of the speed sensorless control system of PMSM greatly.In order to realize the speed sensorless control in the whole speed range and consider the influence of parameter changes at the same time,different algorithms are adopted in different speed areas to estimate the speed and parameters.Firstly,the mathematical model of the IPMSM(Interior Permanent Magnet Synchronous Motor)is built,then the state equation is established,and DEKF(Dual extended Kalman filter)is introduced to realize the speed sensorless control of the IPMSM in the middle and high speed range.The stator resistance and speed of the motor are estimated simultaneously,and the two are mutually corrected.In the low speed region,the mathematical model of IPMSM considering high frequency signal is established,and the speed estimation in the low speed region is realized by signal injection method which is independent of the motor parameters and mathematical model.In order to achieve the smooth transition of the two algorithms,the weighted average scheme is introduced,and a full speed range speed observer composed of DEKF and signal injection method,which can identify the speed and stator resistance simultaneously,is constructed.The simulation and experimental results show that the composite observer can estimate the speed in the whole speed range,the steady-state performance and dynamic performance are satisfied,and the parameter robustness of the system is improved.