设计1台额定功率300 kW、额定转速2 700 r/min的永磁发电机，要求中心高不大于225 mm，则功率密度约是普通电机的6倍，电机的温升控制成为了亟待解决的问题。为了降低电机的温升，设计了水冷机座，通过有限元仿真计算，发现电机绕组端部温升仍然较高。为了进一步降低绕组端部温升，在原水冷机座基础上增加了4条轴向通风道，并使冷却水能够对4条轴向通风道内的冷却气体进行冷却，电机端部温升计算值显著降低。为了验证这种混合冷却结构的可行性，制作了1台样机并进行型式试验，试验结果与设计值基本吻合，从而验证了设计的准确性和轴向通风道对端部绕组散热的有效性。

The aim of the research is to design a permanent magnet generator with rated power of 300 kW and rated speed of 2 700 r/min. For this generator, the center height should be no more than 225 mm, and the power density is about 6 times that of ordinary generator. Therefore, the temperature rise control of the generator has become an urgent issue. In order to reduce the temperature rise of the generator, the water cooling frame is designed. Through the finite element simulation calculation, it is found that the temperature rise at the end of the generator winding is still high. In order to further reduce the winding end temperature rise, four axial ventilation channels are added on the basis of the raw water cooler base, and the heat exchange between the cooling water and the cooling gas in the four axial ventilation channels is made possible. In this way, the calculated temperature rise of the generator end is significantly reduced. In order to verify the feasibility of the hybrid cooling structure, a prototype is made and type test is carried out. The test results are basically consistent with the design values, which verifies the accuracy of the design and the effectiveness of the axial ventilation channels for heat dissipation of the end windings.