풍력발전기의 역률 개선을 위한 DCVM 포워드컨버터

Abstract

Wind power generation would be the most potent alternative energy source in near future with growing concern about the shortage of natural energy resources by a sharp increase in energy consumption and environmental pollution. In wind power generation, wind energy is converted to electrical energy via rotary blades and an alternator. With small size power generation system used in private houses, large scale wind power generators of megawatt range are also commonly under commercial generation. It is said that the price of power electronic device occupy 25%-35% of whole system price. Power conversion device can be divided into two parts, one is AC/DC converter part which converting ac generator voltage into dc voltage and the other is DC/AC converter part linking with utility line. AC/DC converter should meet the various input voltage requirements, and also high power factor should be achieved.

In this paper, high power factor and high efficiency forward converter is suggested by driving it with LC filter in DCVM operation. Being operated by DCVM, the forward converter's loss is dramatically decreased with the presence of voltage zero period when switch is turned off. It suggests that IGBT switch can be used in wind power generator system without further loss in the switching period which is favorable in large power rating system.

Through the experiment, output of 24 [V], 72 [W] is obtained with 90 [Vrms], 110 [Vrms], 260 [Vrms] input voltages. Power factors of 0.998, 0.995 and 0.993 are achieved with input voltage of 90, 220, 260 [Vrms] respectively. Besides simple control circuit without current sensor, it is profitable for miniaturization because the size of inductor and capacitor could be small. Also, THD of the converter is within 10% for the input voltage range from 90 to 260 [Vrms]. So, DCVM forward converter can be the possible AC/DC converter in wind power generation with varying input wind power.