Research On High Speed Magnetic Isolation Drive Technology Of Wide-band Gap Semiconductor

With the rapid development of the third generation wide band gap semiconductor industry,SiC MOSFET is more and more widely used in the industrial field.Comparedwith the ordinary Si semiconductor power device,it has the advantages of high temperature resistance,high voltage resistance,low loss and high switching frequency.Therefore,the commercial value of SiC MOSFET in the market is gradually increasing.The drive circuit is very important for the operation of semiconductor power devices.Because the characteristics of SiC MOSFET are different from those of ordinary Si devices,it is more sensitive to parasitic parameters in the circuit under the condition of high frequency operation.Therefore,the design of SiC MOSFET drive circuit should take more factors into consideration and has certain research significance.In this paper,the characteristics of SiC MOSFET are analyzed in detail,and the necessary and sufficient conditions for the design of SiC MOSFET driver circuit are summarized,including the bidirectional transmission of high speed magnetic isolation signal,the fault protection of SiC MOSFET,and the suppression of high frequency cross talk in half bridge structure.The main research contents and results are as follows:(1).first introduced the kinds of wide bandgap semiconductor devices and the development trend both at home and abroad,compared the ordinary Si and SiC semiconductor semiconductor devices in the performance difference,highlighted the SiC semiconductor's advantage in industrial USES,clarify the meaning and value of the thesis,on the basis of the identified driver circuit isolation methods and drive solutions.(2).The characteristics of SiC MOSFET are analyzed in detail,the influence of parasitic parameters in the circuit on the switching process of SiC MOSFET devices and the energy loss are analyzed through simulation modeling,and the influence of different gate resistors on gate drive with parasitic parameters is discussed for the modeling study of gate drive.(3).Detailed analyses the characteristics of magnetic isolation drive technology,the signal transmission technology of magnetic isolation drive principle were studied,respectively designed to share the sync pulse magnetic isolation transformer group of modem forward and reverse fault protection signal transmission circuit,and has carried on the theoretical analysis of the whole circuit design,circuit simulation and prototype making,The bidirectional transmission of drive and fault signals of SiC MOSFET can be realized reliably,and the key technology can be integrated to transmit signals through PCB coreless transformer.(4).Detailed analysis of the SiC MOSFET in the process of work may produce the fault,on the basis of the design of the drive circuit to increase the design of protection circuit,and in some traditional protection circuit to improve and optimize,through the simulation experiment to verify the feasibility of the design,improve the safety performance of SiC MOSFET in work.(5).The equivalent model of SiC MOSFET working in half bridge structure is established,and the causes of high frequency crosstalk are analyzed in detail.Through simulation and theory,it is proved that gate crosstalk mainly comes from the charging and discharging displacement current of the Miller capacitor of the device and the induced voltage introduced by co-source inductor in the drive circuit.In order to suppress the crosstalk,the optimization measures are put forward in the circuit layout,and the control strategy of variable gate voltage is adopted.