Skip-duty control method for minimizing switching stress in low-power multi-level Dc-Dc converters

This paper addresses the problem of large sporadic transient voltages across the switches of low-power multi-level dc-dc converters and introduces a digital control-based method for their elimination. The physical origin of the large voltage transient spikes occurring at certain operating points, corresponding to zero current ripple operation, is explained. A control-based solution for the problem, based on the avoidance of the critical operating points, i.e. on skipping of critical duty ratio values, while maintaining tight voltage regulation and symmetric inductor current waveforms, is introduced. The effectiveness of the control method is demonstrated with a wide-input 10 V/ 3 A output, 1 MHz, three-level buck dc-dc experimental prototype, where it is shown that the skip-duty control completely eliminates the sporadic spikes.