Novel Approach to Modelling Electromechanical Coupling and Testing its Self-Consistency in Micro-Scale Kinetic Electromagnetic Energy Harvesters

The electromagnetic transduction mechanism is very common in kinetic (vibration) energy harvesters, and even miniaturised implementations of electromagnetic harvesters employing microtechnologies have been reported in the literature. The key task in the design and modelling of energy harvesting devices is to incorporate electromechanical coupling correctly as it is responsible for the efficiency of the device and the amount of energy that can be converted. Despite the clear physical nature of interaction between electrical and mechanical domains in the case of the electromagnetic transduction mechanism, a detailed description and accurate modelling are challenging. Today, there exist a number of methods for modelling of magnetic fields and flux appearing in these devices in three dimensions, all of them requiring computation efforts. At the same time, the engineering community prefers compact (or lumped) models of such devices because it eases the analysis, circuit design and co-simulation of electronics and resonators in the same simulation environment. In this paper, we discuss a new self-consistent model of electromagnetic energy harvesters based on first principles of electromagnetics and mechanics that results in a lumped model that is convenient for analysis and design.