Switching Sequence Synthesis for Minimizing RMS Current in a Single-Inductor-Multi-Output Converter

Abstract

Single-inductor-multiple-output (SIMO) DC-DC converters offer a compact power management solution in low power applications for simultaneously powering multiple DC loads. While using a time-interleaved PWM control technique, there exist multiple feasible switching sequences in a SIMO converter. The primary research focus in the recent past remains in minimizing the cross regulation and coupling effects. However, there has been a little emphasis on the design of the switching sequence for minimizing the RMS inductor current in order to minimize the conduction losses. This paper is aimed in finding a suitable switching sequence for the reduction in the RMS value of the inductor current iL in a SIMO converter. The primary objectives are to (i) find the practically feasible switching sequences, (ii) identify the sequence with the lowest RMS value of iL at a given operating condition, and (iii) develop an optimal algorithm for dynamically varying operating conditions. A prototype of dual-output buck converter is made. A three-output simulated and a two-output experimental case studies are considered, and analytical predictions are found to be consistent with the results.