Temperature-Field Analysis of an Air-Cooled Line-Start Solid-Rotor PMSM With Alternating-Hollow-Solid Slot Arrangement

The Line-Start-Solid-Rotor PMSM (LSSR-PMSM) has the characteristics of simple supporting equipment and low cost compared with the ordinary frequency conversion PMSM system, and has the characteristics of excellent starting performance and high efficiency compared with the induction motor, which has the potential to replace the traditional frequency conversion PMSM system in the applications such as oilfield pumping machines and coal mills in power plants, etc., which require the motor to have excellent starting performance. Due to the structure of solid rotor and cage bars, the rotor of LSSR-PMSM generates more eddy current loss, which leads to higher temperature rise. The magnitude of eddy currents is also related to the starting capacity of the LSSR-PMSM. Considering the actual situation of the compact mechanical structure of the LSSR-PMSM with small and medium capacity, a novel alternating-hollow-solid rotor topology without additional mechanical structure is proposed to suppress the temperature rise of the LSSR-PMSM. Besides, the solid slots of the structure serve to provide starting torque, and the hollow groove serves to change the state of fluid motion in the air gap and enhance the thermal dissipation on the rotor surface. This paper reveal the air motion law in the hollow slot and analyze the influence of the air slot on solid rotor heat transfer path. And the prototype with the scheme that optimizes the motor performance and heat transfer efficiency was machined to verify the conclusions. The research content of this paper provides ideas for the design of LSSR-PMSM.