Time Multiplexing Control for Power Converters

Controlling two outputs with a single controlling switch in the power converter presents difficulties when two contrasting actions are required: to raise one output and decrease the other. This paper studies the application of time-multiplexing control (TMC) technique on power converters, with particular interest on single-switch multiple-output converters. Each output has its own feedback control circuit but these discrete feedback control loops are intermittently switched to regulate the duration of the ´on period´ and ´off period´ of the power switches. The inclusion of multiplexing logic to incorporate multiple controllers will improve the regulation of the auxiliary outputs and the main output within the tolerances required for electronic equipment. The output errors can be distributed between the outputs according to the time sharing factor of the time multiplexing logic controller. Simulation and experimental results on a single-switch dual-output flyback converter with and without TMC are reported to verify the error sharing capability of the proposed method. This control approach suggests a possible solution in improving the overall performance of the power supply in terms of output voltage regulation.