Analysis and Mitigation of Bifurcation in Cascaded DC-DC Converters under Asynchronous Mode of Operation

Switching ripple interaction between source and load subsystems in a cascaded configuration of power converters leads to creation of oscillations that carry subharmonics and different multiples of switching frequencies. These ripples highly affect the intermediate bus voltage in the cascaded system resulting in reshaping of the modulation signal in the source converter. This will manifest itself in the form of bifurcation in the output voltage and current of the converter. To investigate this phenomenon, a cascaded converter under the asynchronous mode of operation is considered. According to our analysis, by implementing judiciously selected phase shifts, the bifurcations caused by the switching ripple are substantially minimized or even eliminated. The proposed technique is validated through simulation and experiment.