A Feed forward Voltage Mode Controlled ZVS based Phase shifted 300W full bridge DC-DC converter for military application

Abstract

This paper is a conversion solution to an advanced development of critical power supply systems in military application. A compact size high power density i.e. 25.26 watt/inch3 DC-DC converter is designed and developed. An appropriate topology of a ZVS based Phase Shifted full -bridge DC-DC converter is selected based on advantages of reduced switching losses and stresses with fixed switching frequency of 100KHZ. A PWM Controller UC1875 is used which has features of programmable output delay for resonant switching action with both voltage and current modes of controlling options. A feed forward voltage mode control is utilized which is easier to design and analyze with good noise margin and stable modulation process and improved line regulation. The Proposed topology is implemented on a hardware prototype with a single output of 30V/10A using input voltage that ranges from 18-36V with an efficiency greater than 80%. An opto-isolation is provided instead of transformer for feedback loop to minimize the size, complexity and cost. A fault tolerant design, this converter host circuit protection features such as over voltage, over current, efficient thermal protection and inbuilt EMI/EMC filters. The converter is realized in a very small size of 102mm×92mm×20.5mm aluminum package.