Wound field synchronous motor with hybrid circuit for neighborhood electric vehicle traction improving fuel economy

Increasing the low mileage associated with electric vehicles is a major requirement. Improving the efficiency of the traction motor is one solution to solve the mileage problem. In this study, we propose a method to improve the efficiency of a wound field synchronous motor (as the traction motor) in case of neighborhood electric vehicles. The wound field synchronous motor is a salient pole machine that generates a negative reluctance torque when operating in the second quadrant, reducing its efficiency. However, second quadrant operation is inevitable due to voltage limitation in the high-speed range. Here, we propose a hybrid circuit comprising U, V, W windings and X, Y, Z windings. The high-speed efficiency of the wound field synchronous motor is improved by changing the connection between the windings. Further, a neighborhood electric vehicle with a wound field synchronous motor was simulated using an advanced vehicle simulator (ADVISOR) to verify the proposal. The hybrid circuit increased the fuel economy of the electric vehicle by up to 3.8%. Finally, a validation experiment was conducted using a fabricated motor prototype.