DESIGN AND IMPLEMENTATION OF CLOSED LOOP LCL-T RESONANT DC-TO-DC CONVERTER USING LOW COST EMBEDDED CONTROLLER

Annamalai Annamalai

doi:10.3844/ajeassp.2012.291.300

Abstract

The aim of this study is to simulate and implement open loop and closed loop controlled DC-DC converter for stand-alone wind energy system. Wind turbines, however, are not always very efficient in the wind speeds that are most common to a region. Typically, wind energy systems are designed to be highly efficient in high wind speed and have a cut-off wind speed- below which no energy is captured. In remote locations where wind energy is used for battery charging, the energy lost below the cut-off wind speed could be used for trickle charging or maintaining a battery’s fully charged state. Wind turbines are most efficient when they are operated at one specific Tip-Speed to Wind-Speed Ratio (TSR). Therefore, for the efficient capture of wind power, turbine speed should be controlled to follow the ideal TSR, with an optimal operating point, which is different for every wind speed In this system, the DC-DC converter in the DC link with a constant dc voltage to the load, a DC-DC converter will allow the voltage at the output of a diode bridge rectifier to be controlled. In low wind speed conditions, the voltage may be lowered to prevent the dc link from reverse biasing the diode rectifier. Under high wind speed condition, the voltage may be increased, reducing I2R losses. In addition, adjusting the voltage on the dc rectifier will change the generator terminal voltage and thereby provide control over the current flowing out of the generator. The LCL-T resonant inverter system for both open loop and closed loop DC-to-DC converter systems are simulated using MATLAB simulink power system blocks. This converter has advantages like reduced transformer size, reduced filter size and current source characteristics. The simulation studies indicate that LCL-T type for open and closed loop DC-DC converter can be used with stand-alone wind generator. Constant voltage can be maintained at the output of DC-to-DC converter by using a PWM rectifier at the output. Embedded controlled DC to DC converter is fabricated and it is tested.

Highlights

Small-scale stand-alone wind energy is increasingly viewed as a viable and sometimes preferred source of electrical energy
For the efficient capture of wind power, turbine speed should be controlled to follow the ideal to Wind-Speed Ratio (TSR), with an optimal operating point, which is different for every wind speed In this system, the DC-DC converter in the DC link with a constant dc voltage to the load, a DC-DC converter will allow the voltage at the output of a diode bridge rectifier to be controlled
The simulation studies indicate that LCL-T type for open and closed loop DC-DC converter can be used with stand-alone wind generator

Summary

Introduction

Small-scale stand-alone wind energy is increasingly viewed as a viable and sometimes preferred source of electrical energy. For example, remote villages in developing countries or ranches located far away from main power lines. Wind energy is a quiet alternative to remote diesel generation-that sometimes depends on excessive transportation and fuel storage costs- and an economically justifiable alternative to a grid connection. It has been shown that a remote load has only to be a matter of a few miles away from a main power line for a stand-alone wind generator to be cost-effective (Kellogg et al, 1998). A typical, small-scale, stand-alone, wind electric system is composed of a wind turbine, a permanent-magnet

Objectives

Results

Conclusion