A new PWM method for a 3-phase 4-leg inverter based on the injection of the opposite median reference voltage

摘要

In this paper, a new carrier-based pulse-width modulation (PWM) technique for a voltage source inverter (VSI) is presented. The new modulation law is obtained using a particular configuration of a control allocation technique based on a per-switching-state formulation of the 4-leg 2-level inverter. The resulting modulation law is equivalent to the injection of the opposite of the median reference voltage as a zero-sequence voltage. This particular solution produces a smooth transition from a continuous modulation mode at low modulation depth to a discontinuous modulation mode at high modulation depth. This hybrid solution makes it possible to focus on the THD for low output voltages and reduce losses for higher voltages.