Improvement on impedance model of electromagnetic energy harvesting systems

The existing equivalent impedance model of electromagnetic energy harvesters (EMEH) has considered only the single-harmonic relations among the current, voltage, velocity, and force in the dynamic electromechanical system. The modeling accuracy is insufficient, given the interference of high-order harmonics, which gets more severe under practical low-Q (quality factor) induction coil designs. This paper introduces an improvement to the conventional single-harmonic model by taking into account the influence of the practical low-Q coil and the high-order harmonics in the EMEH system. The extended impedance method (EIM) is used to characterize the nonlinear components in the system. The improvement of modeling accuracy is validated by experimental results.