Research On High-speed Application And Adaptive Drive Circuit Of SiC/GaN Power Device

Due to the high switching speed,low on-resistance and other excellent characteristics of silicon carbide and gallium nitride power devices.The power electronic converters develop towards high frequencies and high efficiency.However,high-speed applications of silicon carbide and gallium nitride power devices have many problems such as turn-off overvoltage,turn-on oscillation and bridge circuit crosstalk.These problems limit the switching speed of power devices.This paper studies the problems existing in high-speed applications of silicon carbide and gallium nitride power devices.This paper first analyzes the effect of circuit parameters on the switching characteristics of the power devices based on a standardized test circuit.Based on LTspice software,a double-pulse simulation platform was built to evaluate the influence of gate resistance,power loop inductance,common source inductance,and gate-drain parasitic capacitance on the switching characteristics of the power device.This paper standardizes the selection of test equipment and test points through theoretical analysis and experimental verification to provide a theoretical basis for the standardized testing of the switching characteristics of Si C MOSFET and Ga N HEMT.Then,this paper analyzes the mechanism of the turn-off overvoltage in detail based on the turn-off process of the power device.Based on the terminal impedance analysis method,this paper analyzes the effect of the high-frequency decoupling capacitors on the turn-off overvoltage.It provides a theoretical guidance for the selection and design of high-frequency decoupling capacitors.This paper analyzes the effect of common source inductance of non-Kelvin packaged devices on turn-on oscillation.The SRD drive circuit is proposed to suppress the turn-on oscillation of non-Kelvin packaged devices,thereby further increasing the turn-on speed of the power device and reducing the turn-on loss of the power device.Finally,this paper analyzes the crosstalk mechanism of crosstalk in bridge circuit based on different packaged devices.A double-pulse experiment platform was built to evaluate the effects of the common source inductance of the passive tube,the gate resistance of the passive tube,the gate resistance of the active tube and the drain junction capacitance of the passive tube on the crosstalk of the bridge circuit.In order to avoid the misleading of the bridge circuit,this paper proposed an RCD type bootstrap negative voltage drive circuit suitable for bridge circuits.The driving circuit only needs an auxiliary power supply to realize the gate-source negative voltage turn-off of the bridge circuit,and the negative turn-off voltage is flexible and adjustable,not affected by the duty cycle.