Optimal PWM for Two-level Inverter fed High Speed Induction Machines

The typical fundamental frequency of a high speed machine and the limited switching frequency lead to low pulse ratio in inverter fed drives. To obtain a good harmonic performance at low pulse ratio an optimal PWM technique is introduced in the paper. The optimization is done for the lowest loss-factor, which is proportional to the square of rms value of current harmonics. Calculation is done for the whole modulation region for different voltage vector sequences at several pulse ratios up to 59. The performance of the optimal PWM technique is demonstrated by experimental tests.