Research On SiC MOSFET Module Characteristics And Its Modulation Strategy Of Three-phase Two-level Inverter

With the emergence of the third generation of new wide bandgap semiconductor materials,the power electronics field is undergoing continuous improvement and innovation.People are paying more and more attention to the improvement of efficiency and power density of the converter and the entire system to promote the new era energy efficient development.Compared to Si-based devices,Silicon Carbide metal-oxide-semiconductor field-effect transistor(SiC MOSFET)has great advantages in switching frequency,high voltage and high temperature resistance.In this paper,SiC MOSFET module(CAS300M17BM2)is used as the research object,whose own characteristics of the device and the application in three-phase inverter were studied.Based on the analysis of silicon carbide materials and their structural characteristics,the static and dynamic characteristics of SiC MOSFETs are analyzed in detail.In the aspect of static characteristics,the influencing factors are analyzed in combination of output characteristics,transfer characteristics,on-state resistance,bodydiode and distribution capacitance between the electrodes.In terms of the dynamic characteristics,the SiC MOSFET turn-on and turn-off process is analyzed in detail,and specific numerical expressions are given for each power parameter in each stage.A double pulse test platform based on three-phase inverter is constructed.Simultaneously,SiC MOSFET and Si IGBT modules with the same power level are compared and tested,and their switching losses under different load currents and crosstalk problems under different gate drive damping coefficients are analyzed.And a reference to drive design is given.The working characteristics of the third quadrant of SiC MOSFET are studied.Combined with the traditional space vector pulse width modulation(SVPWM),a synchronous rectification discontinuous pulse width modulation(SRDPWM)method is proposed.The double Fourier analysis is used to solve the SRDPWM modulation.The frequency domain mathematical model is established to quantitatively analyze the characteristics of each harmonic.Combined with the synchronous rectification mode of SiC MOSFET,the switching loss and on-state loss model of SiC MOSFET two-level inverter under SRDPWM modulation strategy are established.The experimental prototype of SiC MOSFET three-phase two-level inverter is designed and the equivalent thermal resistance model of inverter and heat sink is established.The influence of different heat sink parameters on the heat dissipation performance is analyzed by Icepak software,and the heat sink is simulated and optimized design.The SiC MOSFET three-phase inverter experimental platform was developed,and the superiority of the double Fourier analysis of the established loss model and harmonic performance was verified by experiments.Experiments were conducted to compare the efficiency of SRDPWM proposed in this paper and SVPWM under different switching frequencies and different load powers.The results show that SRDPWM can significantly reduce the SiC MOSFET switching losses and improve the efficiency of the inverter.The higher the switching frequency,the more obvious the efficiency improvement is,and the advantage of this modulation method in the light load and high switching frequency work places is more obvious.