Coupled inductor‐based triple output bi‐polar converter with duty cycle estimation

Abstract

SummaryMulti‐output converters have been accepted in many portable and display applications due to their ability to optimize hardware both in terms of number of switches as well as on the inductances. Many of these applications require the input voltage to be both stepped up and stepped down, and some applications also require negative outputs. This paper proposes a non‐isolated converter topology which can generate positive buck and boost outputs and also a negative output using a coupled inductor. The converter can operate in continuous and discontinuous conduction modes (DCMs). A detailed analysis of the converter is done in both modes, and it is shown that the outputs can be controlled by direct real‐time analytical estimation of the duty cycle in DCM. Coupled inductor enables the possibility that more than one output can be simultaneously supplied, reducing the cycle time and increasing throughput. Independent control of all three outputs confirms that cross‐regulation is avoided due to real‐time continuous estimation of the duty cycles. The proposed converter is verified by building a hardware model for multi‐output voltages of 5, 24, and −5 V with an input voltage of 12 V using a Spartan‐6 FPGA controller. Experimental results validate that 94% converter efficiency and regulated output voltages under full load conditions. Steady state and dynamic performance of the converter illustrate the effect of suggested control technique to alleviate cross‐regulation in multi‐output converters.