Research On Calculation Modeling Of Power MOSFET Loss In High Frequency Photovoltaic DC-DC Converter

High frequency photovoltaic DC converter is one of the key parts of photovoltaic power generation system.In high-frequency photovoltaic DC converters,power MOSFET switching loss is an important factor to be considered in the optimization of converter circuit parameters and heat dissipation design.This dissertation first studies the extraction and modeling methods of power MOSFET parasitic parameters.Based on the extracted parasitic parameters,the transient process of power MOSFET switching under the influence of parasitic parameters is analyzed,a simple and easy-to-use power MOSFET switching loss calculation model is proposed,and the influence mechanism of parasitic parameters on switching loss is explored.Then,on this basis,considering the circuit structure and operating characteristics of LLC resonant converter,a power MOSFET loss calculation model in LLC resonant converter is established.And build a simulation circuit in Pspice to verify the power MOSFET calculation model established in this dissertation.In addition,an experimental platform was also built to verify part of the research content of this paper.The main work content is as follows:(1)The modeling and extraction of parasitic parameters of MOSFET are studied.The parasitic capacitance equivalent model and transconductance calculation formula of the power MOSFET have been established.In addition,the extraction method of parasitic inductance of power loop and device package is also studied.(2)Aiming at the problem of complicated modeling of power MOSFET switching loss caused by parasitic parameters,a simplified calculation model of power MOSFET switching loss considering parasitic parameters is proposed.(3)Through time-domain analysis of LLC converter,combined with the proposed power MOSFET switching loss calculation model,and considering the transient characteristics of the device under the half-bridge structure,the power loss calculation model of LLC resonant converter is established.(4)The simulation circuit was built in Pspice,and the above research content was simulated and verified.And the hardware experimental circuit was built to verify the simplified calculation model of power MOSFET switching loss considering parasitic parameters.