Suppression of B-Field & E-Field Effects on Resolver due to Overhang Components in Traction Motor Applications

Permanent Magnet Synchronous Motor (PMSM) is a favorite choice for traction applications because of their high power-to-weight ratio, torque-to-current ratio, high efficiency. In PMSM motors to perform the electronic commutation, resolvers are required to detect the rotor position. Resolvers are placed nearer to the end windings of the stator by considering the Mechanical Assembly and interfacing aspects. In high-power traction applications, due to higher current, there will be a significant influence of electric fields (E-fields) and electromagnetic fields (B-fields) on the rotor position sensor due to overhang components. The magnetic field induced by end-winding changes the excitation field, the magnitude of which decides the rotor angular position. This distortion of the excitation field will impact the sensing position and performance of the resolver. Analytical equations discussed in this paper also highlight that the machine output torque decreases with position error at higher speeds. The magnetic field in the overhang components of the winding is noticeably three-dimensional. In this research study, a 3D finite element simulation is performed to examine and suppress the impact of the B-fields and E-fields. In this approach, the influence of E-fields and B-fields is determined in radial and axial directions by creating planes. From this approach, shielding is provided for the resolver, due to that the effects of B and E-fields are suppressed by 88-95%. Due to the suppression, the resolver can deliver a precise rotor angular position for the motor.