Simulation and Analysis of Thermal Fields of Rotor Multislots for Nonsalient-Pole Motor

In this paper, the temperature distribution characteristics of rotor multislots for a 20-MW-class nonsalient-pole synchronous motor adopting one and a half of a parallel cooling channel system at the rotor end are studied. The physical model with a half-axial and a quarter-circumferential segment of the motor is established. Based on the finite-volume method (FVM), three-dimensional turbulent governing equations are numerically solved. First, the flow field of the computational domain is calculated. Second, the temperature field of the rotor, including six slots, is simulated. The results show that the peak temperatures of insulation and coolant are all located on the pole centerline per slot, and a one-and-a-half parallel cooling channel system is beneficial for decreasing the temperature of the rotor body. Finally, we compare the peak temperature of the longest slot and the average temperature of rotor windings simulated by the FVM with the values obtained by lumped-parameter thermal network and electrical resistance method, respectively. The errors meet the engineering requirement. The air volume flow rate at the inlet of the motor by simulation is accurate compared with the experimental results. This paper shows that it is feasible to design a 20-MW nonsalient-pole synchronous motor from the thermal analysis point of view.