A PWM strategy for reducing torque-ripple in inverter-fed induction motor

A new PWM strategy suitable for an inverter-fed induction motor is described. The output waveforms in the proposed PWM inverter are investigated both theoretically and experimentally. Although the output waveform is a nonsinusoidal waveform, the induction motor driven by the proposed modulating signal produces approximately constant torque. A modulating signal for the three-phase PWM inverter is obtained by superposing a rectangular wave on the specific trapezoidal wave whose flat portion is 120 degrees. By using the proposed modulating signal, the amplitude of the fundamental component is increased by about 17 percent more than that of a conventional sine wave inverter. The new system reduces the torque ripple as well as achieving the effective utilization of the DC supply voltage for the inverter.<
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