Research On DSP Based Two-stage Bi-directional DC-DC Converter

Bi-directional DC-DC Converter(hereinafter,"BDC")is the two-quadrant operating DC-DC converter.The power can flow in either direction.BDC can perform two or more functions,so it is one of the useful methods to reduce the size,the weight and the cost of the power system.Two-stage Bi-directional DC-DC Converter which is composed with non-isolated BDC and DC transformer was adopted in the experiment.The Two-stage BDC has the advantages of high power density,convenient to optimum design and convenient to modularize.Because many active components are needed in BDC ,and the power must be controlled to flow in either direction,Digital control method is adopted in this paper .Soft-switching working mechanism of buck/boost BDC is researched firstly,harware design and experiment analysis are given at the same time.Working theory of half bridge converter with passsive and lossleess CDD sunbber circuit is analysed particularly,then a DC-DC/500W converter of 270VDC input and 360V output is designed.On the base of above , the paper introduces the fundamental and characteristics of half bridge bi-direction DC transformer.The soft switching condition is researched and the experiment result is given too . At last , a prototype/300W used in aviation of 27VDC(low voltage) and 270VDC(high voltage) is designed and achieved based on TMS320LF2407A DSPcontroller.Experiment results verifies that the converter gets a high efficiency,digital control and malfunction protect are also achieved.