Three-Dimensional Finite-Element Analysis and Optimal Design of Hybrid-Excitation DC Brush Motor for Automotive Engine Start Applications

This paper presents the design of a hybrid-excitation-type DC brush motor, simulation and analysis of a commercially available diesel generator starter, and use of the finite-element analysis software, Maxwell 3D, to develop the motor model. Moreover, an improvement is proposed for magnet fixing and compared with the traditional dovetail groove design. Magnet fixation via the splicing method effectively mitigates magnetic saturation; therefore, a power density analysis is performed to demonstrate that the proposed improved design can increase the power density of the magnet per unit volume. Additionally, this work involves another structural improvement, i.e., the hybrid-excitation-type optimization design, along with the use of the Taguchi algorithm to optimize the power of a part of the stator structure; variance analysis and sensitivity are also considered. The analyses justify the selection of control factors for the optimization design. At a rated speed of 3,400rpm, the output power of the motor increases by 25.1% relative to the prototype. Considering the economic benefits and applications to automobile engines in product development, the new motor configuration enables performance improvements without increasing the weight of the car body.