Random PWM Technique for Dual-Inverter-Fed Vector-Controlled Induction Motor Drive

From the analysis of harmonic spectrum of conventional PWM techniques, it is observed that a high amount of energy is concentrated around the harmonics of switching frequencies as side bands resulting in acoustic noise, vibration and electromagnetic interference. These effects can be mitigated by spreading the spectrum and reducing the magnitude of harmonics around switching frequencies. This can be achieved by introducing the randomness in control signals. In this paper a simplified and more generalized carrier-based random pulse width modulation (RPWM) technique is presented for asymmetrical dual-inverter-fed vector-controlled induction motor drive. In the proposed RPWM technique a zero sequence signal is added to the commended reference signal to obtain the required modulating signal. The randomness is introduced in generating the zero-sequence signal. To validate the proposed RPWM technique, simulation and experimental studies are carried out and the results are presented. © 2015, Brazilian Society for Automatics--SBA.