A novel SHE-PWM method for five level voltage inverters with quarter-wave symmetry

A novel formulation of quarter-symmetry SHE-PWM problems for five-level voltage inverters is proposed. The SHE modulation scheme features a broad solution space and can eliminate a large number of low-order harmonics. An effective method for obtaining initial values of switching angles is proposed. To illustrate the effectiveness of the proposed SHE method, a five-level voltage source inverter with elimination of 11 low-order harmonics is investigated. The SHE-PWM equations that can eliminate harmonics from 5^th to 35^th with modulation index M varying from 0 to 1.15 are formulated, and solutions 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.