Optimal pulse pattern determination based on Pulse Harmonic Modulation

The design of optimized modulation schemes at low pulse ratios, e.g. Selective Harmonic Elimination (SHE), has been widely studied. However, most previous work has focused on half-wave symmetry pulse patterns. For variable speed and variable torque applications, non-half-wave symmetry SHE modulators depending on the power factor angle still achieve highly efficient inverters in many power factors. Unfortunately, few papers have studied inverter loss on non-half-wave symmetry SHE modulators. Thus, this paper proposes our original SHE method: Pulse Harmonic Modulation (PHM). Its mechanisms are explained in detail. Additionally, different pulse patterns of PHM are quantitatively compared. On the basis of this comparison, several design criteria are proposed for modulators at low pulse ratios.