Study On SiC MOSFET Module Drive And Protection Circuit

With the rapid development of power electronic technology,the performance of power devices based on silicon(Si)materials is difficult to meet the growing technical demands.Featuring the excellent characteristics of silicon carbide(SiC)materials,silicon carbide metal field effect transistors(SiC MOSFETs)have significant advantages in high-frequency,high-voltage,high-temperature,and high-current power electronics applications.However,the electrical stress,switching oscillation and EMI caused by higher switching speeds,weaker short-circuit withstand capability,and current sharing issuses in high-power applications.All these problemes are key obstacles to its wide applications.To address these issues,this paper starts with theoretical and experimental research work from four aspects of SiC MOSFET module:behavior model parameter calibration,gate drive circuit technology,protection circuit technology and current sharing technology.The main research contents and results are as follows:1.A calibration method for behavior model parameters of SiC MOSFET is proposed in this paper.Firstly,the factors affecting the transient accuracy of SiC MOSFET behavior model are analyzed in theory and simulation.It is found that the sensitivities affecting the transient accuracy parameters of the SiC MOSFET behavior model are CGDD,CGS,VGS,th,RG,int,gm,CDS and CDj,respectively.On this basis,a calibration method for behavior model parameters of SiC MOSFET is proposed in this paper.In SABER,finally,the simulation with calibrated model was carried out under the conditions of different gate resistance,operating temperature,switching current,bus voltage and applied gate capacitance with double-pulse test.The results show that,compared to the experimental results,the proposed calibration method for SiC MOSFET behavior model has obtained better works under different application conditions.2.A multi-gate voltage active driving technology is proposed to improve the switching performance of SiC MOSFET module.Firstly,the structure of the SiC MOSFET module gate drive circuit is introduced:and the effects of the drive circuit parameters on the switching characteristics of the SiC MOSFET module are analyzed in detail.On this basis,a method based on drive voltage decrement during the voltage and current slopes is proposed to address the overshoots,oscillations and EMI problems.Finally,the performance of the proposed method was verified with double-pulse test under different operating temperatures and load currents.The results show that,compared with conventional gate driver,the proposed method with optimal delay time can effectively reduce the switching electrical stress of the SiC MOSFET module,suppress the switching oscillation caused by high-speed switching and parasitic parameters,and cas achieve a tradeoff between switching losses and electrical stress.In addition,the proposed method has more cost and efficiency advantages in high-power SiC MOSFET module applications.3.A short circuit protection strategy for SiC MOSFET module based on power detection is proposed.First,the short-circuit types and characteristics of SiC MOSFET modules are introduced.The factors affecting the short-circuit performance of the SiC MOSFET module are analyzed,including the driving voltage,bus voltage and operating temperature.Secondly,the defects of the existing desaturation detection and dI/dt detection protection circuits in the SiC MOSFET short-circuit protection appli cation are analyzed and discussed in detail.On this basis,a short-circuit protection strategy for SiC MOSFET module based on power detection is proposed.Finally,the feasibility and advantages of the proposed protection method was verified under different application conditions The results shows that the proposed protection method can timely detect short-circuit and turn,off fault current in different short-circuit conditions.Compared with conventional gate drives,there is no blanking time and the worse the short circuit:the faster the protection response.4.A variable gate voltage active parallel current sharing strategy for improving the parallel current sharing performance of SiC MOSFET modules is proposed.First of all.the parameters affecting the current sharing performance of SiC MOSFET modules in parallel are analyzed in theory and simulation.which including driver parameters,power module parameters and power loop paramneters.On this basis,an active current sharing strategy is proposed by dynamically adjusting the gate drive voltage to achieve automatic synchronization of current edge and current slope between paralleled SiC MOSFET modules.For more paralleled SiC MOSFET modules,the efficiency and accuracy of the proposed current sharing strategy with master-slave and chain control topology are compared and analyzed using simula.tion methods The results show that the proposed current sharing strategy can effectively improve the current sharing problem between paralleled SiC MOSFET modules.In addition,the proposed method associated with the master-slave control topology can obtain a better current sharing performance in more paralleled modules.