Research On Gate Driving Technology Based On Sensitive Parameter Control

Power semiconductor switching devices are widely used in modern rail transit,power energy and other industrial fields.Taking full advantage of the performance of power switching devices lays great foundation on the reliablility,safety and energy-saving operation of power electronic equipment.In modern power semiconductor switching devices,Si IGBT and Si MOSFET are most widely used.Si C MOSFET,Si C IGBT and Ga N FET also gradually occupy part of the market.These switching devices are gate voltage driven devices.The characteristics of gate driven control directly affect the switching performance of the devices.The existing drive protection circuitry not only implements normal gate voltage control,but also incorporates detection and protection functions to monitor the status of the switching device.Sensitive parameters such as gate driving resistance and gate voltage have a significant impact on gate oscillation,power loop current and voltage overshoot and switching loss.Using active gate drive technology to dynamically adjust the sensitive parameters such as driving resistance and gate voltage to find the optimal working point under specific applications can take full advantage of the working performance of the device and effectively improve the operation reliability of the device.In this paper,the gate drive characteristics of power semiconductor switching devices are studied,and a multi-level synchronous synthesis driving technology is proposed.The active gate drive of variable voltage is used to reduce the electrical stress and power loss in the switching process of power devices.Firstly,the gate structures of Si IGBT,Si C MOSFET and Ga N FET devices are studied,and the parameters of gate drive circuit and gate characteristics are compared.Based on Si IGBT,the relationship between gate oscillation,current and voltage overshoot,switching loss and gate sensitive parameters is deduced,and the influence of different sensitive parameters on switching characteristics is analyzed.The switching characteristics are modeled by PSpice,making a comparioson among the influence degree of a single switching characteristic by different sensitive parameters as well as the influence degree of a single sensitive parameter on different switching characteristics.Based on the theory and simulation analysis of sensitive parameters,the active gate drive methods of variable resistance,variable voltage and variable current are studied and comparing the advantages and disadvantages of typical circuit topologies.Secondly,an active gate drive method of variable voltage is proposed,which applies a certain driving voltage for a period of time in the current change stage of the switching process to realize the compromise optimization between current and voltage overshoot and switching loss.The effects of driving voltage and its action time on current voltage overshoot and switching loss are analyzed.The optimization objective function is designed,and the changing rule of the value of action voltage and action time at the optimal working point is analyzed,the influence of the action voltage and action time at different working points on the objective function is compared,the changing trend of the optimal working point with the load current is studied.Finally,the experimental verification is designed.The variable voltage active gate drive circuit including multi-source function expansion,multi-level synchronous synthesis and load current detection.The multi-source function expansion outputs multi-level voltage,the multi-level synchronous synthesis selects the driving voltage,and the load current detection determines load current.Through simulation and experiment,the active gate drive method of variable voltage can realize the compromise optimization of current voltage overshoot and switching loss.Under the same overshoot control effect,the active gate drive can reduce the switching delay and switching loss compared with the conventional drive.The driving circuit can effectively detect the load current and adjust the action time,veritifing that the gate driving technology based on sensitive parameter control proposed in this paper is reasonable and effective.