Generalized harmonic elimination method for interleaved power amplifiers

This paper examines interleaved converters in which tolerances of the cell inductors are taken into account. Normally, an equally distributed phase-shift is applied to the PWM of an interleaved converter, which results in optimal ripple-cancellation for the output current. This is true for the ideal case in which cell inductors are identical. However, in practice, cell inductors are not equal, leading to the return of fundamental switching-frequency subharmonic components in the spectrum of the output current. In this paper it is shown that for this situation an optimal phase-shift exists. A generalized method is proposed to calculate the phase-shift in such a way that harmonics, such as the fundamental switching frequency harmonic component, are removed from the spectrum. For three parallel cells an analytic and a geometric method, supported by simulation results, to calculate the phase-shift is presented. Finally, results from an experimental setup are shown to verify the proposed ideas.