Double-Integral Fourier Analysis of Interleaved Pulse Width Modulation

Double-integral Fourier analysis is utilized in this paper to study steady-state and dynamic characteristics of interleaved buck converters. The method presented is general and does not assume commensurability of the perturbation and the switching frequency. The resulting PWM model captures the complete spectrum of the PWM output and predicts the time-varying effect at all frequencies where it may occur. The PWM model is further used to explain the effect of interleaving on harmonic cancellation in steady-state operation, and to prove that there is an optimum interleaving angle that results in minimum residual harmonics. Cancellation of sideband components among interleaved converters under dynamic conditions, and the possibility to extend control bandwidth beyond the conventional limit of half the switching frequency are also discussed