Study of field coupling in dual mechanical port electrical machines

The dual mechanical port electric machine (DMPM) is a new breed of electric machines. The two ports can input or output mechanical energy freely, work in motor or generator mode at the same time respectively. But field couplings exist between the inner and outer air-gaps, which affects the performances of the two mechanical ports greatly and brings much trouble in controlling. This paper studies the characteristics of the field coupling in permanent magnet DMPM motors. The main factors inducing the field coupling are analyzed. A decoupling control algorithm of DMPM is presented, based on which a four-order system thus can be converted into two two-order systems. The Lyapunov equations are constructed to prove the stability of the algorithm. Simulations and experiments are carried out. The results prove that the algorithm can decouple the system effectively.