Design and thermal analysis of a self-circulating integrated composite cooling system for high-speed PMSG in hybrid power generation system

Thermal design is a crucial aspect of high-speed permanent magnet synchronous generator (PMSG) design, particularly given the compact size of these motors, severe heat accumulation, and stringent heat dissipation requirements. Specifically, long-term operation at high temperatures can result in performance degradation and may even endanger system safety. To overcome these issues, a self-circulating integrated composite cooling system (SCIC-CS) for high-speed PMSG is designed in a hybrid power generation system. The innovation of this cooling structure lies in the high integration of the cooling system components with the high-speed PMSG. The cooling system integrates the oil tank under the high-speed PMSG, and uses a hollow shaft to scatter the heat-dissipating oil into the interior of the motor and return it to the oil tank to complete the cycle, thereby achieving overall heat dissipation of the stator and rotor, and using reinforced heat sinks to promote the joint cooling of the oil and PMSG, effectively alleviating the serious heat accumulation in the rotor and the problem of excessive heat transfer within the system. An analytical model of the composite thermal resistance network considering the effect of engine heat transfer is established, and the relationship between engine heat transfer and motor heating is analyzed. In order to verify the effectiveness of SCIC-CS and the accuracy of the thermal network model, a hybrid power generation system with a high-speed PMSG is developed to test the cooling performance of the prototype, with evaluation results demonstrating the feasibility of the novel cooling system and the accuracy of the thermal network model.