Half-wave symmetry SHE-PWM method for multilevel voltage inverters

Half-wave symmetry SHE-PWM method has a large number of valid solutions, which are beneficial to optimization design. This paper proposes a novel generalized formulation of half-wave symmetry SHE-PWM problems for multilevel inverters. The advantages of the proposed formulation include simplicity in format, flexibility in PWM waveforms and a broad solution space. Methods to obtain initial values for the SHE-PWM equations are discussed. Take a five-level inverter with M = 0.75 as an example, six sets of solutions for two typical initial phase angles of 0 and 90 degrees are presented. Simulations and experiments are carried out. It is demonstrated that the experimental results agree well with simulated ones, which proves the validity and practicability of the new method proposed.