Research On The Sensorless Control Of PMSM Using Low Frequency Signal Injection

Permanent magnet synchronous motor(PMSM)is widely used in various fields because of its high power density,high efficiency,small size and other advantages.PMSM control system with mechanical position sensor is easy to be disturbed by the environment,and increases the cost,while sensorless control technology makes up for these shortcomings and becomes a research hotspot in recent years.Low frequency signal injection method is a kind of sensorless control technology for PMSM at zero and low speed,Compared with the high frequency signal injection method,the low frequency signal injection method does not have obvious noise because of its low injection signal frequency,which has certain application value.Firstly,this paper introduces the basic principle of low frequency current injection method,and analyzes its stability.Aiming at the influence of salient polarity on low frequency current injection method,the current compensation scheme is adopted to improve it.The dynamic and static performance and parameter sensitivity of the low frequency current injection method are analyzed in detail through simulation,and the effectiveness of the current compensation scheme is verified.Aiming at the shortcomings of low frequency current injection method,such as small speed observation range and general dynamic performance,an adaptive observer enhanced by low frequency current injection method is proposed.At low speed,the low frequency injection module output is used as the correction speed to adjust the adjustable model of the adaptive module,so that it not only has good low-speed observation accuracy,but also has good dynamic performance.The feasibility of the combined observer is verified by simulation,which proves that it has a wide speed observation range and can smoothly switch from low speed to medium high speedBased on the experimental platform of TMS320F28335,the feasibility of low frequency current injection method and adaptive observer enhanced by low frequency current injection method is verified by experiments.