Contents I. Introduction
With the development of electrical propulsive shipping and more-electric aircraft system, volume and weight of the drive system is strictly limited. Further research on electrical drive systems with higher power density, lower weight and cost is in great request. Two double Y shift 30° permanent magnet series-connected motor system helps to solve the problem. Characteristics of the series-connected system are as follows: The stator windings are connected in series and the two series-connected motors are mechanically independent supplied by single control platform and inverter drive system. Harmonic currents of one motor are limited owning to the filtering effect of the other machines stator impedance. Energy in braking process of one motor can be used by the other motor directly and process of energy feedback into the bus is skipped which helps to decrease the capacity of the inverter [1]–[4].
