Performance analysis of microcomputer based PWM strategies for induction motor drive

The results presented in this paper were specially chosen to provide a comparative basis for assessing the performance of an induction motor drive operating on PWM strategies that have been suitably modified to facilitate real time implementation using microcomputers. The comparison is made for harmonic copper loss with and without skin effect, end leakage losses and stray load losses. The simulation results confirm that for low speed operation, selective harmonic elimination technique is unsuited. The regular sampled strategies, in general, are superior to harmonic elimination technique in low and mid frequency range and associated harmonic losses could be as low as one-fourth of the losses occurring with SHE strategies. Sensitivity of the optimal regular sampled strategies for relative phase shift is also investigated. Reduction of 6% in harmonic copper losses occurs for phase shift of 180/spl deg/ at modulation depth of 1.2.