SIMULATION OF RESONANT DCWDC CONVERTER

Abstract

With the fast advance in VLSI technology, smaller and more powerful digital systems are available. These systems require power supply with higher power density, lower profile and higher efficiency. PWM topologies have been widely used for these applications. Unfortunately, hold up time requirement put huge penalties on the performance of these topologies. Also, high switching loss limits the power density achievable for these topologies. To achieve high power density and high efficiency simultaneously, resonant converter topologies are used. Nowadays a lot of work concerning the resonant converters is going on and out of all the resonant load converter topologies, LLC converter is mostly used because of its advantages over the previous topologies. The dissertation presents a systematic and comprehensive approach for the optimal design of LLC converter. It also discusses the closed loop control of LLC converter with an objective to include rejection of input supply and load transients. Two different control strategies have been employed: 1. Variable frequency control with the help of FUZZY logic. 2. PWM control. Simulations results have been obtained for the above methods for a reference set point, input supply and load variations. Further over current protection techniques have been studied for practical implementation of the converter.