An Asynchronous Exciter fed Brushless Wound Field Synchronous Motor Drive for Electrified Vehicle Application

This paper introduces the concept using a brushless wound field synchronous motor as a viable solution for Electrified Vehicle (EV) traction motor. It initially presents a comparative discussion between the main EV traction machines used presently and subsequently presents the system configuration of a proposed asynchronous exciter fed brushless wound field synchronous machine. For the proposed topology, a wound rotor induction machine (WRIM) is used along with a rotating diode bridge rectifier to control the field excitation of the wound field synchronous machine (WFSM), thus eliminating the need of the slipring-brush assembly. For the design of the overall proposed machine, the Toyota Prius 2004 traction interior permanent magnet synchronous motor (IPMSM) has been considered as the baseline and the basic stator frame size, airgap length and also the shaft diameter of the WFSM has been considered to be the same as that of Toyota Prius 2004 IPMSM. The rotor for the proposed wound field synchronous motor is designed and presented along with its FEM based simulation results. This is followed by the complete design and Finite Element Method (FEM) based simulation of the exciter induction machine. Indirect rotor flux-oriented vector control is applied on the exciting induction machine to control the excitation of the synchronous motor generating a minimal motoring torque for the exciter machine. Vector control is applied on the wound field synchronous motor component to satisfy the required tractive torque keeping the d-axis component of its armature reaction at zero. Control performance is simulated through MATLAB (Simulink) software and is presented. A comparison of major performance indices and cost is finally presented between the proposed machine and the Toyota Prius 2004 machine.