Optimum Design of the Electric Vehicle Traction Motor Using the Hairpin Winding

Recently, according to Eco-technology accelerating, new types of traction motor with the high efficiency and power are demanded. This paper presents that the Hairpin winding is applied to a design of the electric vehicle traction motor for the high efficiency and power density. Generally, the winding method using the toroidal coil has the restriction which is the unnecessary spaces between coils. However the Hairpin winding method can reduce the gap between coils, therefore the space factor is higher than that of winding methods. However, because of using the full pitch winding and wave winding, this method has the disadvantages of increasing the THD of back electromotive force and torque ripple. Thus, to minimize the THD and torque ripple, the full factorial method, Response surface method and the step skew to the rotor are applied. The paper presents the motor design using the Hairpin winding for the high space factor, and the analysis result by using RSM, the step skew and full factorial method shows the reduced space harmonics.