Research On High-speed Permanent Magnet Synchronous Motor Drive Based On SiC MOSFET

With the rapid development of electric vehicles,the drive system of electric vehicles is developing towards higher speed,efficiency,voltage and power-density.Since the drive system of electric vehicle mainly using high-speed permanent magnet synchronous motor(PMSM),the development of electric vehicle drive system promotes the development of PMSM and has raised higher anticipation on PMSM drive.As the promotion of efficiency,power density,bus voltage of electric vehicle drive system and the increasing speed of PMSM,there are higher requirements of the switching loss,switching frequency,voltage stress,environmental temperature tolerance of motor drive.Currently,most motor drivers using Si IGBT are being more and more difficult to meet engineering requirements.The new wide bandgap semiconductor silicon carbide power devices have irreplaceable advantages in the application of high-speed PMSM,due to the advantages of faster switching speed,lower switching loss,lower switching on-off loss,higher blocking voltage,and higher environmental temperature tolerance.With the development of silicon carbide material manufacturing technology,the electrical performance of silicon carbide power devices is optimized and the price has a downward trend,so the research on silicon carbide power devices in high-speed PMSM drive has practical application value.Although there are a lot of advantages of silicon carbide power devices,there are some still problems to be solved in the motor drives.This paper analyzes three common problems of SiC MOSFET when applied in high-speed PMSM drives.Above all,with increasing switching speed,the parasitic inductance of converter circuit results in the voltage of drain-source overshoot and the oscillation.It is analyzed by modeling the main circuit and the suppression scheme is verified through experiments.Secondly,as the control-frequency increasing,the demands of control-platform and control-algorithm are even more stringent.In the end,the main problem of the application of SiC MOSFET is the phase-leg crosstalk and gate-drive oscillation.Compared with the Si IGBT,as the switching speed of SiC MOSFET power device greatly improving,the change rate of drain-source voltage in the switching transient is very large.Hence the problems of phase-leg crosstalk and gate-drive oscillation are highlighted.In the paper,the generation of crosstalk and gate-drive oscillation are firstly analyzed in stages.Secondly,the causes of crosstalk and oscillation are analyzed by modeling and simulation in frequency domain.Then,a novel suppression scheme of phase-leg crosstalk and gate-drive oscillation is proposed and analyzed in stages.The scheme is verified in frequency domain and the applicable device parameters are selected by calculating in time domain.According to the scheme,the continuous simulation experiments are done through LTspice.Finally,it is proved that the scheme is effective by conducting double pulse experiments in different voltages and currents.In the end,this paper completed the design of the high-speed PMSM platform.The designed motor drive system can sample the stator line current,the stator line voltage and bus voltage,provide the overvoltage protection of busbar pumping voltage,gain the speed of rotary transformer,detect the temperature of bearings and windings with over-temperature protection,and contain short circuit protection,to ensure the safe operation of motor and its drive.Double pulse experiments are done to verify the short circuit protection and overcurrent protection.The continue experiment done in the condition of the inductance obstruction load and the high-speed PMSM load respectively.