Simulation and Implementation of Quasi Resonant DC-DC Converter

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doi:10.3844/jcssp.2012.1730.1738

Abstract

Problem statement: A half-bridge LLC resonant converter with a voltage doubler rectifier has a simple structure and its Zero-Voltage-Switching (ZVS) capability is excellent from zero to full load condition. But conduction loss is more due to high circulating energy thus reducing the system efficiency. Moreover a variable frequency control method makes the control circuits more complicated than those using the Pulse Width Modulation (PWM) control method. Thus, DC drive has lower efficiency when it operates on light loads. Approach: To improve the efficiency of the DC drive under light loads, a PWM-controlled quasi-resonant converter is proposed .It has simple control circuits and less conduction loss compared to a half-bridge LLC resonant converter under light load conditions. The proposed converter has a half-bridge LLC resonant converter along with an auxiliary circuit. The load regulation of the proposed converter can be achieved by an auxiliary circuit. Thus the proposed converter is expected to be suitable sustaining power module for the efficiency enhancement of DC drives. As the magnetizing inductance of the proposed converter is larger the circulating energy is considerably reduced under light load conditions. In this study the operational principle, design and modeling of QRC DC-DC converters for DC drives are presented. The PWM controlled quasi resonant converter is implemented using PIC microcontroller 16F184A. Results: The capacitor filter in the output is replaced by pi filter to produce DC with minimum ripple. The experimental results and simulation results are compared. This converter has the advantages like reduced number of switches, reduced transformer and filter size, reduced ripple, reduced switching losses, reduced switching stresses and increased power density. Conclusion: The experimental results closely agree with the simulation results.

Highlights

For the DC motors operating in the textile mills high efficiency is needed primarily under light load conditions
In order to improve the efficiency under light loads a Pulse Width Modulation (PWM)-controlled quasi-resonant converter is proposed which has simpler control circuits and less conduction loss (Xie et al, 2007; Xu et al, 2006) compared to a half-bridge LLC resonant converter under light load conditions
In this proposed converter the bidirectional auxiliary circuit consists of a two auxiliary MOSFETs A1 and A2, auxiliary inductor LA and auxiliary capacitor CA

Summary

INTRODUCTION

For the DC motors operating in the textile mills high efficiency is needed primarily under light load conditions. High efficiency and low noise (Xie et al, 2007; Xu et al, 2006) but a large variation in switching frequency is needed to control the output voltage. Input voltage with a step disturbance is shown in Fig. effectiveness of the proposed converter configuration and. When the output voltage increases, the error its control strategy, a cost effective new PWM controlled quasi resonant converter has been developed, simulated and successful implemented in real time in open loop using PIC 16F877A Micro controller for a prototype. Transformer primary side voltage is shown in Fig 3e.The output waveform is complement of the driving pulse.

Name of the components

CONCLUSION