Research On High Switching Speed Behavior Of Silicon Carbide Based Inverter In PMSM Driver

Multi-electric or all-electric aircraft is an important development area for aircraft in the twenty-first century.The high power density drive system is one of its core supporting technologies.Increasing the motor speed can reduce the volume and weight of the motor which increase the power density at a limited output power.Therefore,the high-speed permanent magnet synchronous motor(PMSM)has draw much attention in recent years.As the speed of PMSM is proportional to the power supply frequency,the high-speed PMSM driver demands a high switching frequency.The Si devices are limited by switching speed and power level,so the Si devices based inverter can not meet the requirements of the high-speed PMSM driver for high switching frequency.The Silicon Carbide(SiC)devices have many advantages compared with Si devices.The most fitful advantage for high speed motor drive is the high speed switching capability.With SiC devices,the high power and high switching frequency inverters for motor drive become possible.Taking SiC MOSFET module as an example,a SiC MOSFET module driver is designed to satisfied the driving requirement,and its switching characteristcs are tested in a double pulse circuit.The turn-off time of SiC MOSFET is related to the load current,so an adaptive control strategy of dead-time with variety of load current is proposed.A mathematical model between dead time and load current is established.An adaptive dead-time optimization control strategy is proposed,combining with current sampling to realize dynamic dead-time adaptive optimization in wide range of load current.Due to the high switching frequency of the SiC MOSFET based PMSM driver,a larger EMI problem will be generated,causing a significant motor current ripple.By adopting the PWM control strategy with variable switching frequency based on peak current prediction,one can reduce the harmonic component of the referenced switching frequency and the value of the peak current ripple.In accordance with the requirement of the ripple current,the switching frequency is adjusted in real-time according to the load current.