Design and Analysis of an Integrated Modular Motor Drive for More Electric Aircraft

Although many permanent magnet synchronous motors (PMSMs) are used as the driving source for aerospace applications, the motor and converter are not integrated. This leads to large volume and low power density of the system. This article proposes an SiC-based integrated modular motor drive (IMMD) as a potential solution, in which the SiC converter is placed at the end of the stator core of the motor. The converter is directly connected to the end-turn windings of the motor so as to reduce the wiring cable losses, with the motor and converter being cooled by an integrated water-cooled housing, significantly reducing the weight of the system and improving the power density. First, the topology of a five-phase IMMD is briefly introduced. Then, the influence of the number of slots on the output performance of the motor is analyzed with the aim of improving the power density of the system. Because the system integration will cause the loss density of the motor to sharply increase, this will thereby cause the local temperature of the IMMD to be higher. A detailed analysis and calculation of the thermal design will be required to improve the reliability of the system in high-temperature environments. The skewed rotor method is adopted so that the torque ripple of the fractional-slot motor is suppressed in the high-speed region. The results show that these methods can increase the power density of the IMMD and expand the speed range of the motor so as to meet the needs of different stages during the whole flight of more electric aircraft.