Analysis and calculation of electromagnetic and temperature field in a hybrid excitation synchronous generator

摘要

This paper presents a hybrid excitation synchronous machine (HESM). As a new type of machine, the HESM is expected to have the advantage of high power density, high efficiency, and controllable magnetic field. It is essential to give full considerations of the HESM in the design stage. Hence, the electromagnetic and the thermal analysis are paid special attention in this paper. At first, no-load characteristic is introduced, as well as the structure and operating principle of the HESM. The calculated and experimental results agree well. As the heat source of thermal analysis, it is important to predict loss accurately. In the next step, the iron loss is analyzed by finite element method, including the loss distribution feature and the influence of field current on the iron loss. Considering overheating may result in the irreversible demagnetization of the permanent magnet and insulation failure of coil, a 3-D computational model is created to conduct the thermal analysis using the predicted loss as heat source, based on the theory of heat transfer. The permanent magnet and the field winding, locating in the rotor, are analyzed emphatically due to its weak cooling condition. The calculated temperature by the numerical method is compared with the experimental result. This study can provide some design references for this type of HESM.