Role of end-ring configuration in shaping IE4 induction motor performance

The performance characteristics, particularly the starting performance of direct line-fed induction motors, which are mainly influenced by the design of the rotor, are crucial considerations for end-users. It is quite a challenging issue for motor manufacturers to enhance the starting performance of existing mass-produced motors with minimal modifications and expenses. In this paper, a simple and cost-effective method to improve the starting performance of a commercial squirrel-cage induction motor (SCIM) is proposed. The influence of geometric parameters of the end-ring on the performance characteristics, including starting (locked rotor) torque, pull-up and break down torque, starting current, rotor electric parameters, current density, power losses, and efficiency have been comprehensively investigated. It has been revealed that among the other end-ring design parameters, the ring thickness has a significant effect on the performance characteristics. An optimal end-ring thickness is determined, and its performance characteristics have been compared to those of its initial counterpart. Numeric and parametric analyses have been conducted using a 2D time-stepping finite element method (FEM). The FEM results were validated using experimental measurements obtained from an 11 kW SCIM prototype.