Optimal design of electromechanical devices using a hybrid finite element/air-gap element method

This paper contributes a mathematical framework for rotating electric machine optimal design. The proposed method utilizes a hybrid finite element/air-gap macro-element method, with steepest descent optimization. In particular, the air-gap element is advantageous for torque optimization, since it directly yields a smooth magnetic field function in the air-gap and an analytic expression for torque, based on the magnetic potential solution at the vertices of the finite element mesh. The sensitivity of an arbitrary objective function with respect to changes in geometric design parameters can be used in the steepest descent method. For illustration purposes, the optimization process is applied to a simple electromagnet for torque maximization.