Traction Synchronous Machine with Rotor Field Winding and Controlled Magnetic Anisotropy

In modern traction drives of cars, trucks, trains, ships, etc. synchronous motors with permanent magnets are used due to their compactness. At the same time, permanent magnets are expensive, and uncontrolled flux of permanent magnets is a problem when it is necessary to provide a wide range of speed control in the field weakening region. An alternative to permanent magnet motors can be motors with a field winding. This paper presents a novel design of a traction synchronous motor with a field winding on the rotor and controlled magnetic anisotropy and discusses the advantages of its use in traction drives. It is shown how the design of this type of motor contributes to achieving a high inverter utilization factor of 0.8 at a constant power speed control range of 3.5:1. The calculations carried out using the finite element method confirm the theoretical conclusions made.