This paper investigates a low-speed direct-driven small generator for the marine energy under the ocean conditions in China. The final dimensions of the generator are determined by analyzing and optimizing the key parameters, such as the length-diameter ratio, the air-gap length and the inner stator diameter. Then the characteristics of the cogging torque and the varying speed and loads are calculated by the 2D FEM and the analytical formulas to analyze the running performance. Further, a prototype is fabricated and the manufacturing test is conducted to validate the design. The experimental results show that the designed generator can meet the requirements of the rated output power 200 W, and enjoys a good performance under the conditions of the varying speed and loads. This research may serve as a reference for designing and controlling the low-speed direct-driven generators for the marine energy.

marine energy generation  /  permanent magnet generator  /  electrical machine design