Study on Improving Precision of Analysis of Buck Ratio and Power Efficiency of Tapped-Inductor Low Buck Ratio DC-DC Converter Circuit

Abstract

Analysis precision of buck ratio and power efficiency in buck DC-DC converter circuit is improved by proposing adaptive equivalent circuit of flywheel diode in the circuit. In conventional analysis, the flywheel diode was replaced with single resistor of constant resistance independent of change in average diode current. Therefore its analysis precision was limited caused by large difference in voltage-current characteristics of the replaced resistor between that of the actual flywheel diode. We proposed replacing the flywheel diode with series circuit of resistor and voltage source changed their resistance and voltage according to change in average diode current. In analysis results, error in theoretical value compared with measured value of the buck ratio can be reduced from 23.7% to 6.61% in a conventional buck DC-DC converter circuit, and from 20.4% to 9.24% in tapped-inductor low buck ratio buck DC-DC converter circuit. In the analysis of power efficiency, error in theoretical value compared with measured value can be reduced from 22.5% to 5.45% in the conventional circuit, and from 25.4% to 4.76% in the low buck ratio circuit.