Dynamic Response Mechanism And Suppression Methodology Of Silicon Carbide MOSFET Gate-source Voltage Interference

The Silicon Carbide(SiC)power MOSFET,featured with fast switching speed,high voltage resistance and high temperature tolerance,gains a broad prospect in the field of high-frequency and high-power application.However,the pulse voltage and pulse current,caused by the high-speed switching,interfere with the gate-source voltage,which threatens the reliability of the converter,impedes the performance of SiC MOSFETs,and limits more application of SiC MOSFETs in the field of power electronics.This paper proposes the dynamic response model of gate-source voltage to solve the problem that the mechanism of gate-source voltage interference oscillation is still unknown.The dynamic response model of gate-source voltage is featured with concise mathematical representation and straightforward physical meaning.Based on the equivalent circuit of the junction capacitance,the power loop model and the driver loop transfer functions are deduced,and the dynamic response model of the gate-source voltage is proposed,derived from the double circuit transfer function of the driver and power loops.Then the dynamic response mechanism of the gate-source voltage is investigated.The accuracy of the model was verified by comparing the experimental results with the calculated results.The dynamic voltage response model of the gate-source is the theoretical basis for researching the interference suppression method.The gate-source voltage interference is an outstanding challenge,caused by the characteristics of SiC MOSFET with high voltage change rate and high current change rate.This paper establishes the pulse-current-gate-voltage transfer function and pulsevoltage-gate-voltage transfer function,respectively,according to the specific transient characteristic parameters of SiC MOSFET.The interference suppression method based on driver and power double loop inductance decoupling is presented.Based on the transfer function model,a standard second-order system to describe the dynamic process of interference transfer is obtained.A normalized system parameter expression form is introduced,and an analytical optimization design method for SiC MOSFET driving parameters is proposed.Finally,theoretical analysis and experiments verify the effectiveness of the interference suppression method and the rationality of the driver parameter analytical optimization design method.The existing interference suppression methods still cannot balance the high switching speed and the voltage stability of gate-source voltage.Based on transconductance gain negative feedback mechanism,a gate negative feedback active driver is proposed.In this method,the auxiliary P-channel MOSFET,structing the negative feedback regulation mechanism,is introduced nearby the gate and the source.Then the negative feedback automatic control is adopted to bypass interference.Not sacrificing the switching speed of SiC MOSFET,the interference of the gate-source voltage is automatically suppressed to realize the stability under the high-speed switching.The principle of circuit operation is analyzed,and the rules for parameter design are put forward.The feasibility of building a driver circuit based on the negative feedback mechanism and the effectiveness of stabilizing the gate-source voltage by the gate negative feedback active driver were proved by the experimental verification.The influence mechanism of stray parameters of the driver circuit on the loss of the power converter system is not completely studied.This paper reveals the system dynamics mechanism explaining driver circuit stray parameters' effect on switch characteristics.Then,based on this mechanism,a driver circuit design strategy is proposed to reduce switching loss,by comprehensively considering the characteristics of the driver IC and the voltage interference suppression strategy of the gate-source voltage.Finally,the system dynamics mechanism is applied to PWM rectifier of charging pile of electric vehicle to verify the correctness of the mechanism analysis and the effectiveness of the design strategy.It provides theoretical basis and application design reference for further improving the performance of power converter system in high-frequency and high-power occasions.To sum up,the research in this paper is devoted to improving the reliability of power electronic converters using SiC MOSFETs,researching and establishing the modeling and analysis methodology for the responding of gate-source voltage to high-frequencypulse interference.On this basis,the research of this paper finds out a reliable and straightforward method for suppressing gate-source voltage interference.The critical performance of power electronic converter using SiC MOSFET is optimized by using this interference suppression method to provide theoretical guidance and technical support for the broader application of SiC MOSFET.