Research On High Frequency Power Converter Efficiency Considering Parasitic Parameters

As modern power electronic devices are trending to high frequency and high power, theinfluences of parasitic parameters on the high frequency power converter are also increasinglysignificant. When IGBTs produce high di/dt and du/dt during the turn-on and turn-off process,the existence of parasitic inductance, capacitance and resistance will result in power loss, EMInoise, and damage to the switch devices, as well as adverse effects on the reliability of thecircuit, high frequency response, measurement error and the switch pulse waveform, ect.This paper aimed at the research on high frequency converter efficiency consideringparasitic parameters. The detail research aspects are as follows：Factors influencing the output power and efficiency of high frequency power converterare analyzed. A novel evaluation system of energy efficiency is presented considering theparasitic parameters. Various factors restricting the energy efficiency are taken intoconsideration to realize higher efficiency and higher frequency output.A novel accurate power loss analytical model is proposed. The ring loss is analyzed in asimple way with a clear physical meaning. Considering the parasitic parameters, the turn-onand turn-off equivalent circuits are analyzed in detail. Furthermore, the corresponding lossformulas are deduced. Based on this model, the circuit power loss could be predicted moreaccurately.Take Buck converter as an example, a converter efficiency model is proposedconsidering the parasitic parameters and the efficiency characteristic of the converter isanalyzed by Saber simulation. Matlab curve fitting tool is used for efficiency modelcoefficient fitting. Thus，the converter efficiency can be estimated by sampling input andoutput power based on the efficiency function model，even the operational parameters of thecircuit are unknown. In addition, different parasitic parameters’ effects on Buck efficiency aresimulated by Saber simulation respectively.A high-frequency high-power ZVZCS phase-shift full bridge converter experimentalplatform is built, and the efficiency under different output power is measured and recorded.The proposed power loss model considering parasitic parameters is verified to be moreaccurate than the traditional model, and have a very good consistency with the experimentalresults.