A Randomized Voltage Space-Vector PWM Scheme For Converter-Fed Drive Systems

Random Pulse Width Modulation (RPWM) techniques for voltage-controlled power electronic converters have been attracting an increased interest due to the unique effects of these techniques on the converter-supplied drive systems. In this paper, a feasibility study of the Random Space-Vector Pulse Width Modulation (PWM) scheme is reported aiming at the noise reduction by power inverters.First at all, the paper presents a synthetic review of the state of the art in PWM theory and practice, and take a direction to perfect the conventional PWM.Second, based on the space vector concept and the existing PWM techniques comparison, a new RPWM strategy is proposed and implemented. The new random modulation algorithms are developed both on the two level and three level inverters.Third, the algorithm simulations involving the power spectra are achieved by the computer program developed in this paper. As a result, the power spectra of the electromagnetic acoustic noise is spread to the wide band area and the wide band noise is much more comfortable and less annoying than the narrow band one.Last but not least, the simulated and experimental systematic output proves the validity of the Random Space Vector PWM, which is considered producing the input action of the system.The work covers the new algorithm investigation, the improvement of random number generation and the simulations coming on the PWM appearance, the power spectra, the random number generation model and the power system output. The PWM scheme has been executed in real time in a digital controller and its features have been experimentally confirmed.