Research On Gate Drivers Of Silicon-Carbide MOSFET

Currently, with the intelligent development of power system and establishment of global energy interconnection, power electronic equipment places a more and more important role in power application. As the most important component, the maturity of power switching components determines the degree of power electronic devices. Nowadays, common power switching devices such as MOSFET、IGBT almost are based on Silicon semiconductor. However, due to the existing drawbacks of silicon material, power switching devices suffer from huge limitations. First, silicon semiconductor has lower critical breakdown field strength, which limits the maximum blocking voltage and minimum on-resistance. And the switching losses of silicon power switching devices could not reach ideal states. Second, silicon has lower energy gap and thermal conductivity, which also limits the maximum working temperature and power.Therefore, the third generation semiconductor devices such as SiC、GaN have attracted attention because of the excellent characteristics. And in the area of high voltage and large power application, SiC has more advantages than GaN. As wide bandgap devices, the energy gap of SiC is 3 times than Si, the breakdown strength is 10 times than Si, and the thermal conductivity is 2.5 times than Si. Silicon Carbide MOSFET is one of the mature power switching devices and has been applied commercially. SiC MOSFET has better characteristics, such as high breakdown voltage, high thermal conductivity and high switching frequency. Applying Silicon Carbide MOSFET to PV inverters can improve the power density and efficiency remarkably.Nowadays, the researches about Silicon Carbide MOSFET mainly concentrate on the building of SiC MOSFET models and the test of its good performances, which is limited on the improvement and optimization of Silicon Carbide MOSFET gate drivers. This article summarizes the existing Silicon gate driver circuits and their advantages and disadvantages, and analyzes the gate driver design of Silicon Carbide MOSFET series. First, this paper analyzes the problems when applying the existing gate driver technology to Silicon Carbide MOSFET. On this basis, this paper introduces the principle of the novel gate driver scheme and crosstalk suppression. And then the synchronous Buck converter is used to analyze this new gate driver. This novel topology is also verified by LTspice and experiments. At last, this paper introduces the MOSFET series issue, and applies the novel gate driver to switching devices series topology.The main contents of this thesis are as follows:(1) The first chapter introduced the background and significance of Silicon Carbide power devices. The Silicon Carbide MOSFET applying technologies and design requirements of Silicon Carbide MOSFET gate drivers have been overview in this chapter.(2) The basic principles and working process of the novel Silicon Carbide MOSFET gate driver have been analyzed in detail in the second chapter.(3) Based on the synchronous Buck converter, the Silicon Carbide MOSFET gate driver is verified by LTspice simulation and experiments in chapter three.(4) As to the power switching devices series operating issues, research status on voltage-sharing is introduced; the novel Silicon Carbide gate driver is analyzed and simulated when applying in the series topology.