An Adaptive Current Source Gate Driver Applying For DC-AC Inverter With SiC MOSFET

The rational design of the drive circuit is related to the normal and good operation of the main circuit.With the increase of the voltage level and the switching frequency of the main circuit,Si MOSFET cannot meet the further demands,and SiC MOSFET is being widely used.The driving requirements of SiC MOSFET are approximately similar to Si MOSFET,but the gate of SiC MOSFET usually has a large resistor inside.If it still uses the traditional voltage source drive circuit,the existence of the large resistor will limit the increase in switching speed,which will cause higher switching losses in the application.Besides,the large changing voltage and current under high-speed switching make the effects of du/dt and di/dt more obvious.The voltage and current spikes and EMI problems caused by these require the drive circuit to have the characteristics of stable drive voltage and low impedance of the drive circuit.Otherwise SiC MOSFET cannot work in the optimal state.On the basis of the traditional voltage source drive circuit,there have been many new researches on the drive circuits.Among these circuits,the current source gate driver has more prominent advantages due to faster switching speed and smaller switching loss.In addition,considering the drive current adaptively changing with the working condition of the main circuit also becomes another method to optimize the efficiency of the main circuit.Therefore,this paper proposes an adaptive current source gate driver applying to SiC MOSFET in a DC-AC inverter.Firstly,the principle of the drive circuit and the adaptive control method are introduced,and the correctness is verified by simulation.Secondly,according to the changing characteristics of the inverter load,the minimal total of the drive circuit loss and the switching loss within one switching cycle is considered as the adaptive control design criterion.The constant current drive of the switching state of SiC MOSFET is modeled,and the correspondence between the drive current and load current is solved.Comparing to the traditional voltage source gate driver,the smaller loss of the current source gate driver and the adaptive control method shows more superiority.Finally,according to the design specification,the calculation of the parameters of the drive circuit and the main circuit,the selection of the device and the design of the compensation are completed.A double closed-loop control system for the entire circuit is built.To verify the above analysis,a 200 W current source gate driver has been made to drive a halfbridge inverter.The experimental results show that the current source gate driver can significantly increase the switching speed of SiC MOSFET,the adaptive control can also optimize the circuit working state,and the overall efficiency of the inverter is improved compared with the voltage source gate driver.