Real-time Implementation Of Harmonic Elimination Pwm Technique For Induction Motor

摘要

This paper presents a new method to decrease the switching frequency of novel harmonic elimination Pulse Width Modulated (PWM) strategy for three-phase inverter. The torque ripple of the induction motor can be dramatically reduced by the new PWM technique. The three-phase inverter is associated with a passive LC filter. The commutation angles are predetermined off-line and stored in the microcontroller memory in order to speed up the induction motors on line control. Precalculated switching is modelled to cancel the greater part of low-order harmonics and to keep a single-pole dc voltage across the polarised capacitors. A passive LC filter is designed to cancel the high-order harmonics. This approach allows substantial reduction of the harmonic ratio in the ac main output voltage without increasing the number of switches per period. Consequently, the duties of the semiconductor power switches are alleviated. Simulation results are presented in order to illustrate such algorithm performance. To show the validity of our approach, DSP-based experimental results are presented.