Digital implementation of a new SPWM switching scheme for modular structured mutilevel voltage source inverter

Abstract

This work proposes a new switching scheme for the cascaded multilevel inverter that can be suitably implemented using digital technique. Unlike other schemes, the proposed method is based on the symmetric regular sampling unipolar PWM with a single carrier and multiple modulating signals. Non-transcendental trigonometric equations that define the switching instants of the multilevel inverter are derived. This algorithm is implemented using a low-cost fixed-point micro controller on an experimental five-level cascaded inverter test-rig.