Improved PD-PWM for minimizing harmonics of multilevel converter using gradient optimization

This paper proposes the improved phase-disposition PWM (PD-PWM) method, which optimizes the voltage harmonic performance of multilevel converter. The proposed PD-PWM method adjusts the position and magnitude of the carriers to find out the optimal values, which minimize the THD of output voltages. A gradient optimization method is applied as a form of an optimization-enabled transient simulation. A neutral-point clamped converter (NPC) demonstrates that the proposed method improves the THD of output voltages using PSCAD/EMTDC and MATLAB.