DESIGN AND PERFORMANCE ANALYSIS OF LLC RESONANT CONVERTER

Abstract

High-performance, high-step-up DC-DC converters are required for many battery-powered applications. For example, in order to power a high intensity discharge (HID) lamp ballast used in vehicle headlamps, the dc–dc converter must boost the battery voltage from 12 V to 100 V during steady-state operation. The computer and telecommunications industries have evolved, a well-defined 48 V battery plant is an ideal solution for supplying hours of reserve time during ac mains outages. The dc-input converter must raise the dc bus voltage from 48 V to around 380–400 V. High voltage-gain DC–DC converters are typically used to step-up from low voltage (24–48 V) to high voltage (380–400 V). The challenge for high voltage-gain converters is to create a large voltage gain while maintaining high efficiency over a wide input and load range. Soft-switching approaches reduce switching loss and allow for large increases in converter switching frequency. Early work in this dissertation is based on comparative study of DC-DC step up converters consisting Boost, Cuk, Flyback and LLC Resonant Converter for a input voltage of 48 volts and output voltage at 380 volts working on switching frequency of 100 kHz. At next stage closed loop control of converters is compared for output voltage regulation at 400 volts while a varying input voltage from 18 to 30 volts.