PMSM Sensorless Control Design Based On High Frequency Injection

Precise location of rotor is needed in either vector or direct torque control systems forpermanent magnet synchronous motors (PMSM). For sensorless control, the method ofestimating rotor position with high frequency injection can be effective in resolving theproblems arising in the other senosorless control techniques at low and zero speed. The mainpoint of high freqency injection is to inject high frequency signals from the stator and thendeal with the modulated signals which, due to rotor’s saliency, contains the information ofrotor position. With the series of signal processing technology, the exact location of rotor,which is extracted from the responding high frequecny signals, can be used for establishing aclosed loop sensorless control system of PMSM.At the beginning of this paper a brief overview is given on the newest development ofsenosrless control technology domestically and worldwidely. In chapter 2, the math modelsof PMSM in different coordinates are used to analyse the vector control technology. Chapter3 is focused on the study of high frequency injection method for rotor location estimationonline. Due to the restrictions of traditional phase locked loop (PLL) technology, short timeFourtier transform is proposed to estimate rotor postion by extracting the peak value ofspectrogram and its associated frequency. The matlab/simulink simulation testify its strongabilty in seeking rotor’s position. Finally, from the view of engineering, a set of hardware andsoftware platform design is put forward based on DSP TMS320F2812 chip.