Abstract

Multilevel PWM techniques are extensions of twolevel PWM methods; the multiple levels in these inverters offer extra degrees of freedom and greater possibilities in terms of device utilization and effective switching frequency. Though the SPWM and its variations are popular PWM techniques in multilevel inverters, implementing them in a digital platform is tedious, as the pulse-widths can only be defined by transcendental equations. A dc link capacitor voltage balancing scheme is proposed for an induction motor drive. The motor is fed from with threelevel inverters generating a five level output voltage structure. The proposed inverter vector locations exhibit multiplicity in the inverter switching combinations which is suitably exploited to arrive at a capacitor voltage balancing scheme. This allows the use of a single dc link power supply for the combined inverter structure. The lower order harmonic components in the output voltage waveform are eliminated by raising the carrier frequency.