Jingbo Liu, Jiangang Hu, Longyu Xu
May 15, 2005
IEEE International Conference on Electric Machines and Drives, 2005.
The paper discusses the issues and provides solutions to digital implementation of sliding mode observer (SMO), especially for sensorless controlled induction machine (IM) operating over a wide speed range. An adaptive low pass filter (LPF) is proposed with variable cut-off frequency for a wide speed range, including a programming technique of using over-sampling to increase the sampling rate seen by the SMO. The sampling rate is made much higher than the system PWM frequency. Methods of designing proper gain are given for a specific SMO. Simulation and experimental results based on the fixed-point DSP TMS320F2812 are provided to verify the effectiveness of the proposed methods