Analysis and Modeling of a Voltage Compensated Push-pull DCX Converter

DC Transformer (DCX) is widely used because of its high efficiency and tight conversion ratio. Although the traditional cascade converter can regulated output voltage, it causes a huge loss (over 10% efficiency). The proposed topology outputs regulated voltage with high efficiency and wide input voltage. It consists of a push-pull DCX converter in parallel with a voltage compensation circuit. The compensation circuit only processes part of input power with low stress and low loss; thus, the total efficiency is improved. Two compensation circuits are compared and discussed, then the small-signal model and the control-to-output transfer function are derived. A design example is presented, and the simulation and calculation results verify the theory. The results show that the secondary-side compensation circuit has high efficiency (92.5%), wide input voltage range (±43%), and the efficiency penalty caused by voltage compensation is less than 2.5%.