Coil optimization for linear electromagnetic energy harvesters with non-uniform magnetic field

Abstract

Useful electric power dissipated in the load of kinetic energy harvesters depends among other factors on the electromechanical coupling coefficient and the ratio of the harvester inner impedance and the load impedance. Improving the performance of an electromagnetic harvester is therefore possible by maximizing the electromechanical coupling by optimizing the magnetic circuit design, including the pick-up coil placement, size and shape. At the same time the impedance of the coil needs to be considered and an optimal electric load must be used in order to maximize the useful power. This paper presents a coil optimization algorithm for conditions of known magnetic field and its change in the space exploitable by the coil. The algorithm is based on the greedy search approach with the useful power on load as a cost function to be maximized. It also ensures an optimal and realistic load to be used.