Switching Losses Minimized Harmonic Elimination for Two-level Inverters

In selective harmonic elimination (SHE), if there are N switching angles, N-1 harmonics can be eliminated, however, can we use fewer switching angles to eliminate the same number of harmonics? No one has ever thought about this question. In this paper, based on the discrete representation of two-level PWM waveforms, a binary quadratic programming (BQP) model is proposed to minimize the switching losses and meanwhile eliminate the harmonics. In this model, the switching losses which is closely related to the jump times of the PWM waveform is formulated to a quadratic objective function, and the numerical approximation of the Fourier coefficients are treated as the constraints which control the fundamental and eliminate the harmonics. This BQP model is solved by using the optimization toolbox YALMIP and some results are given, in which the switching angles required to eliminate the same number of harmonics are significantly reduced compared to the SHE method. Experiments on a two-level inverter verify the correctness of this method.