Research On Integrated Circuits Of SiC MOSFET Switching Devices Driver

Silicon(Si)materials are limited by their own band width and have difficulty in meeting the needs of next-generation power electronics systems in terms of switching frequency,blocking voltage,energy consumption,and operating temperature.The superior performance of SiC materials in terms of band width,breakdown field strength,saturation electron drift rate,and thermal conductivity makes it the material of choice for the preparation of next-generation power devices.SiC MOSFET devices are gradually being used in power electronics devices for their fast switching speed,low conduction loss,high voltage,and high-temperature resistance,but the research on SiC MOSFET drive and protection are not studied at the same pace as their devices.Overshoot,oscillation,EMI during switching,and current imbalance when the devices are connected in parallel have become difficult problems in the design of SiC MOSFE drive and protection circuits.At present,there is no single SiC MOSFET driver IC design solution that can combine the Millar platform waveform improvement and the dynamic current equalization function.Therefore,the design of a perfect SiC MOSFET gate driver and protection module is of great importance for the stable and efficient application of SiC MOSFET power devices in power conversion devices.This paper analyzes the driving characteristics of SiC MOSFETs from their device structure and determines the main design parameters of the circuit,such as output voltage and output current,etc.By studying the dynamic switching process of SiC MOSFETs,the mechanism of the formation of the Miller platform of the switching process is analyzed in detail in stages.In brief,the Miller plateau is formed because of the Miller effect generated by the gate-drain parasitic capacitance during the switching process;in addition,the factors influencing the current imbalance when the power devices are connected in parallel are analyzed,and in addition to the fixed parameters such as the threshold voltage of the devices themselves,the gate drive resistance,etc.,can also have an impact on the current distribution.Based on the theoretical analysis,this paper proposes a Miller platform improvement module and a dynamic current equalization module,which effectively solve the overshoot problem caused by the large di/dt rate of change of leakage current during the switching process of SiC MOSFETs and the current imbalance problem when the devices are connected in parallel,reduce the switching loss and improve the power level of SiC MOSFET devices.In this paper,the BCD 30 V process library provided by DB Hi Tek(Korea)is used.The proposed gate drive and protection scheme uses 3.3V/5V as input and outputs a positive gate drive voltage of 20 V and a maximum instantaneous current of 1A,with basic under-voltage protection and current protection lockout functions.The Mille plateau improvement module avoids the plateau of the gate voltage and reduces the drop time of the drain voltage,so that the drain overshoot is reduced and the switching losses are reduced.Besides,the dynamic current equalization module can complete the current imbalance regulation about 8 cycles,improving the stability of SiC MOSFETs in efficiency-critical applications or higher power applications.