Research On Sensorless Control Technology Of Permanent Magnet Synchronous Motor Based On SiC Power Device

At present,MOSFET or IGBT made of Si materials are used as power devices in inverters,but their switching speed is slow,resulting in lower switching frequency,arger switching loss and longer drive signal dead time.As a new wide-bandgap devices,Si C power devices have been widely used in motor drive systems,while achieving high switching frequency,reducing dead time,reducing volume and loss,increasing power density,reducing motor noise of drive system;in order to improve system reliability and further reduce the volume of hardware structure,position sensorless control technology is used to replace mechanical sensors;SVPWM technology is optimized to further reduce PWM high frequency harmonics.The switching characteristic of Si C MOSFET is analyzed,and a dual-pulse test circuit model based on Si C MOSFET devices of ROHM is built.The effects of gate resistance,driving voltage,and parasitic capacitance on the switching character istic of Si C MOSFET are analyzed through simulation.The results show that the use of Si C power devices can greatly reduce the dead time.A sensorless control technology based on nonlinear observer is studied.The voltage and current in the stationary coordinate system are used as the input of the nonlinear observer to estimate the electrical angle,and the phase-locked loop is used to extract the velocity information.The simulation and experiment results verify that the method can realize the sensorless control of permanent magnet synchronous motors,and the accuracy of the sensorless control under different switching frequencies is explored.The research results show that increasing the switching frequency can reduce the speed error and improve the accuracy of sensorless control.The principle analysis and realization method of Modified Single-edge SVPWM(MS-SVPWM)technology are studied,and the harmonic components and switching frequency of PWM are analyzed.A method of switching between Single-edge SVPWM technology and MS-SVPWM technology is designed.The research results show that MS-SVPWM technology can suppress odd multiples of PWM harmonics.The discrete simulation model of the motor control system is established,the phase lag of phase current caused by the RC filter in the sampling circuit is analyzed and compensated,and the influence of phase lag on the sensorless control accuracy is analyzed.Analyze and compensate the dead time effect using SVPWM technology and MS-SVPWM technology,and analyze the influence of the dead time effect on the control accuracy of the sensorless control.The research results show that the phase compensation can improve the dynamic performance of the sensorless control,and the dead time compensation can reduce the angle and speed errors of the sensorless control and improve the control accuracy.