A carrier-based discontinuous PWM modulation for four-leg inverters and applications

Abstract

We review in this paper a carrier-based discontinuous pulse-width modulation (PWM) method for four-leg DC-AC inverters using an extended definition of the classical space vector methodology in which qd and the zero sequence components of the switching vectors enable the development of the expressions of the discontinuous modulation signals that clamp the switching devices to either the positive or negative DC rails for about 1/3 of the waveform period. This modulation scheme is then used for the dynamic control of the voltage of a three-phase (balanced, unbalanced or nonlinear) load with a neutral connection using the concept of nonlinear input-output linearization with decoupling. Simulation and experimental results validate the proposed discontinuous modulation scheme as also the feasible high performance made possible by the control scheme adopted.