Analysis of DC-link current harmonics for unconventional PWM strategies — Application of the double Fourier integral Method

This paper presents a numerical approach for determining the theoretical harmonic components of unconventional pulse width modulation (PWM) strategies such as the Unified-Double Carrier PWM (Uni-DC PWM). The method uses a double Fourier integral formulation to analyze the inverter DC-link current harmonic components, by establishing inner and outer integral limits of this formulation. The provided results of the investigated modulation strategy are demonstrated by comparing with those obtained by Fast Fourier Transform (FFT) analysis of simulated switched waveforms for selected conditions. 3D graphics and general cartographies for global variation of the DC bus RMS current are also presented, together with a comparison of the harmonic performance of a classic PWM strategy and the Uni-DC PWM.