Harmonic elimination by adaptive phase-shift optimization in interleaved converters

Interleaving is a commonly used technique to reduce the output current ripple in parallel connected buck-stages. Harmonic cancellation is achieved by applying a phase-shift to the carrier waves of the pulse width modulator, resulting in a reduced output current ripple at a higher effective frequency. However, optimal interleaving is only achieved when switching cells are identical. When variations between switching cells are taken into account, subharmonic switching-frequency components will appear in the output current, resulting in a higher voltage ripple than designed for. In this paper an adaptive phase-shift control method is proposed which can solve the optimal phase-shift problem. Additionally, it will be shown that the phase-shift values can be determined by only measuring the output current. The proposed algorithm has also been verified on a experimental setup.