Modeling and Control of Sigma DC-DC Converter for High Voltage Bus Converter

This paper presents a Sigma converter for high voltage bus converter. The converter consists of an LLCLC resonant converter and a Dual Transistor Forward Converter (DTFC). The LLCLC resonant converter works in a fixed frequency mode and transfers a large portion of the power using the fundamental and third harmonics. The DTFC is used to regulate the output voltage and transmit a small portion of the power. To better analyze and design the converter, a small signal model of the converter is derived and verified. A controller is designed based on the model.