Research On Modeling Of Silicon Carbide MOSFET Device And Integrated Drive Technology

Silicon carbide has become a typical representative of the third generation power semiconductor materials due to its wide band gap, high breakdown field, high thermal conductivity and high saturation carrier velocity etc. SiC power MOSFET become a hot research which has high frequency, high temperature, low on-resistance etc. Existing device models are built mainly based on Spice, which is difficult to be applied to system-level simulation. And the differences of materials result in Si-based power MOSFET driver circuit is difficult to play the advantages of SiC power devices. So establishing accurate model of SiC power MOSFET based on system simulation software Simulink and designing the high-speed isolating driver circuit which meet the required characteristics of SiC power MOSFET drivers are important to wide application of SiC devices.Firstly,this paper introduces the basic structure and working principle of the N-channel enhancement mode VDMOSFET, and then use high-temperature test platform based on Agilent B1505 A semiconductor power analyzer to test the static characteristics of ST’s SiC power MOSFET SCT20N120. In order to establish a precise device model in whole workspace, this paper designed a complementary testing system, set up a test platform to test the output and transfer characteristics of SCT20N120, and provided comprehensive and accurate data support for device modeling. This method has an important impact in guiding the extraction of other power semiconductor devices’ relevant parameters.Secondly, through the theoretical analysis, this paper established a semi-physical static model of SiC power MOSFET based on traditional Si-based dual-injection lateral MOSFET static characteristics, elaborated the modeling process of MOS core unit, the drain current Id’s compensation and the threshold voltage Vth’s compensation. And the paper gave a method of extracting model parameter based on testing data, established a complete static model of SiC power MOSFET. On the basis of analyzing a simplified MOSFET’s gate equivalent circuit and the switching process of SiC power MOSFET, the paper established a dynamic analytical model of SiC power MOSFET and verified the established model through simulation to analyze its accuracy.Thirdly, based on the parameters comperation of the same capacity SiC power MOSFET and conventional Si-based power MOSFET, SiC power MOSFET driver circuit design requirements were given. This paper also analyzed the equivalent circuit of the driver, compared and analyzed different methods of isolation and power amplifier, designed a drive circuit isolated by optocoupler and a drive circuit isolated by pulse transformer, descriped the operation of drive circuits and the method of critical component selection, and verifyed the designed drivers with double pulse test.Finaly, this paper set up the device model suitable for system-level simulation software Simulink, verified the accuracy of the model by comparing the simulation and experimental data. The design of two drivers were tested on the double pulse test platform, and the impact of resistance to the gate driver driving performance was analyzed, the two drive circuit characteristics were compared, and the feasibility of the two drive circuits was verified.