Improved Research On Driver Design And Control Strategy Based On SiC MOSFET Inverter

In recent years,the wide band gap semiconductor device,represented by silicon carbide(SiC)metallic oxide semiconductor field effecttransistor(MOSFET),has become an ideal device choice for high frequency,high efficiency and high temperature application about voltage source inverter(VSI)due to its advantages of high switching speed,high switching frequency and high thermal conductivity.Therefore,in order to make better use of SiC device’s advantages,aiming at the problems of bridge arm crosstalk under high switching speed and the dead-time effect under high switching frequency for SiC MOSFET VSI,the design of gate driver and the dead-time elimination strategy of inverter are carried out.The main contents are as follows:(1)Due to the effects of higher switching speed and parasitic parameters,crosstalk in a phase-leg configuration of traditional SiC MOSFET driver will be more serious,while the existing drive circuits for crosstalk suppression usually bring the disadvantages of increasing switching loss,switching delay or complex degree,so a gate drive circuit was designed to suppress crosstalk in this paper.Firstly,the cause of crosstalk phenomenon and its typical solution were described.Secondly,based on the idea of adding additional new auxiliary circuit with a triode series-connected capacitor between gate-source terminals to decrease the gate driver impedance when crosstalk occurred,an improved gate driver design method was proposed on the premise of applying a negative-biased turn-off gate voltage.The operating principle and the key parameters design rules were also studied.Finally,a double-pulse testing platform was established to verify the effectiveness of the improved gate driver under the conditions of different drive resistances,input voltages and load currents.(2)With the significant increase in switching frequency of SiC MOSFET device,dead-time has a more serious impact on the output characteristics of inverter.While the traditional dead-time compensation methods have some problems such as poor compensation effect or mistaken compensation.Therefore,an online adaptive dead-time elimination method considering current ripple factor was proposed in this paper.Firstly,the cause of dead-time effect and its traditional compensation method were described.Secondly,based on the dead-time elimination principle,the width of load current’s zero-crossing area was detected adaptively by calculating the maximum value of current ripple in a single modulation period,which made the dead-time effect was effectively eliminated.Finally,An experiment of SiC MOSFET inverter prototype was carried out to compare the effects of dead-time under different switching frequencies,and verify the effectiveness of the proposed method under different voltage modulation ratio.(3)To further analyze the performance of developed SiC MOSFET inverter prototype,the loss distribution and load efficiency between silicon(Si)insulated gate bipolar transistor(IGBT)and SiC MOSFET inverters were analyzed theoretically and compared experimentally.Firstly,an experimental prototype platform of Si IGBT and SiC MOSFET inverters were built.Secondly,the loss calculation model of VSI was given,and its loss distribution and load efficiency were also theoretically analyzed.Finally,based on the experimental platform of Si IGBT and SiC MOSFET inverter prototype,the efficiency of prototype was evaluated at different switching frequency and output power.The research results have important academic value and practical significance for playing better performance of SiC MOSFET inverter,and promoting the application of SiC devices on high switching speed and high switching frequency occasion.