DC Homopolar Machine with Rotating Metal Belts Instead of Brushes to Carry Electric Current

General trend of electric motor development requires such features like being brushless type, efficient and having high power capability. Unfortunately, DC homopolar motors do not locate in the trend of usage commonly in the industry, especially in small size applications nowadays due to its disadvantages like existence of excessive amounts of brushes, although they have high power and torque capability without field weakening issue.  To overcome disadvantageous properties of DC homopolar machine, a new design created without brushes or liquid contacts by following an unusual way. In this new design, a transformer used to induce current in the motor conductors and rectifier circuits which are also assigned as a rotating secondary circuit of the transformer. The conduction path of the secondary circuit is completed with metal belts which are focused parts regarding electrical and mechanical resistances. Finite element method conduction model and equivalent electrical circuit element formulation to take into account viscous damping are created in order to figure out these resistances and to define dimensions for the design. At the end, a belt mechanism and dynamics, whose purpose is to conduct electric current instead of mechanical power transmission, gains a formation and can be understood with a different perspective in DC homopolar machine with metal belt design.

电动机发展的整体趋势要求电机具备无刷、高效及高功率输出等核心特性。尽管直流单极电机（DC homopolar motor）具备高功率、高转矩输出能力且无弱磁问题，但由于其存在电刷数量过多等缺陷，当前在工业主流应用场景中，尤其是小型应用场合，并未得到广泛使用。为克服直流单极电机的上述缺陷，本研究通过非常规思路设计了一款无刷且无液接触的新型电机。在该新型设计中，采用变压器（Transformer）在电机导体与整流电路中感应电流，该电路同时被设置为变压器的旋转副边绕组。副边电路的导通路径由金属带构成，而金属带是影响电气与机械电阻的关键部件。为精准计算上述电阻并确定设计尺寸参数，本研究构建了有限元法导电模型，并建立了考虑粘性阻尼的等效电路元件公式。最终，本研究确立了以导电而非机械动力传输为目标的金属带机构及其动力学特性，为采用金属带设计的直流单极电机提供了全新的理解视角。