Contactless Field Excitation System of Wound-Rotor Synchronous Motor

Abstract

Transferring energy to the rotating parts of electrical machines through brush or slip ring has always been a problem due to maintenance, friction loss and arcing. All of these problems are eliminated with contactless energy transfer systems. In this study, a magnetic resonance coupling (MRC) based wireless power transfer (WPT) system was used in the excitation of a synchronous motor. Single-layer circular planar spiral coils were used in the transmitting and receiving coil design, thus achieving high coupling factor and low thickness. The WPT system successfully transfers energy in low air gaps between the rotating and stationary parts of the electrical machine. Simulations of the WPT model were made with MATLAB and Maxwell 3D. According to the simulation results, the system can operate with over 98% efficiency in a wide frequency band. The system was operated at 100 khz resonance frequency and 50 W power was transferred to the output with 98.22% efficiency. This design is not affected by the rotation of the rotor and does not create an imbalance in the rotor, since the receiver and transmitter coils are positioned parallel and symmetrically. This WPT system offers a reliable, low-cost and low-complexity solution to excite a synchronous motor.