Improved differential-evolution based optimization design of an axial flux MEMS micromotor

This paper presents an optimal design of an axial flux mircoelectromechanical systems (AF-MEMS) micromotor with enhanced power density and efficiency. The micromotor is characterized with dual-rotor and external diameter only around 10 mm. The characteristics of the MEMS micromotor are presented and modeled for optimization design. With the simple but powerful population-based stochastic search technique for solving global optimization problems, the differential evolution (DE) algorithm is adopted for the optimization design of this special motor. Furthermore, according to the characteristics of the micromotor, such as nonlinear, small size and different convergences of optimal variables, a constraint matrix (CM) and a depth search (DS) are proposed to enhance the conventional DE. Such improved DE is beneficial for the search efficiency and accuracy according to calculation results whilst giving an optimal motor with high power density and high efficiency. Experiments and 3D finite element analysis (FEA) are employed to analyze the optimized micromotor and verify the feasibility of the proposed DE.