A Double-Feed Magnetic Resonant Coupling Machine with Air-Gap Windings for High Power Density and Efficiency

Electric vehicles (EVs) and aircraft require motors with high power density. We propose a double-fed motor (DFM) with an air-gap winding (AGWs) capable of operating in the state of magnetic resonance coupling (MRC) to obtain a high power-density and high efficiency. The fundamental characteristics of the DFM with AGW are determined and its high power is attributed to the increase in the product of primary and secondary currents without magnetic saturation of the stator and rotor. Furthermore, the DFM with AGWs operates at high efficiency at high rotational speeds owing to small iron losses. In addition, MRC allows the DFM with AGWs to operate at high speed owing to brushless feeding to the secondary winding. These features yield a high power-density via higher rotational speed and lightweight properties, which are suitable for electric aircraft and vehicles.