A Novel Synchronous Phase Shifted PWM Strategy for Cascaded-H-Bridge-fed PMSM Drive

This paper proposes a novel synchronous phase shifted pulse width modulation strategy for a three-phase five level cascaded H-bridge multilevel inverter-fed permanent magnet synchronous machine drive. The key novelty of the proposed strategy deals with the adoption of the apparent switching frequency to identify a novel optimal frequency modulation index that guarantees voltages half-wave and three-phase symmetries, even if it is a non-integer number. Then, a novel optimal switching frequency-motor speed pattern is defined. The effectiveness of the proposed strategy is verified through experimental analysis, both in steady-state and dynamic working conditions.