Abstract
In this paper investigates the influence of selfinduction on the output characteristics of an electromagnetic vibration energy harvester with two freely moving magnets. In many studies, this effect is either ignored or not considered. However, in resonant vibration harvesters, at high-frequency and high-amplitude excitation, the change in current in the coil becomes significant, which leads to a pronounced effect of selfinduction. To evaluate this effect, a mathematical model that takes self-induction into account was developed, and numerical simulations were performed. A laboratory prototype was also manufactured and tested. A comparison of the results showed good agreement between the calculations and the experimental data. It was found that the maximum output power is achieved at the resonance frequency of the prototype. In this mode, the harvester generates up to 4.75 mV of voltage and 3.4 mA of current at a power density of$0.358 \mu \mathrm{W} / \text{cm} 3$, which is a high indicator for compact electromagnetic systems. Numerical calculations revealed that neglecting self-induction leads to a significant overestimation of output power—at resonance, losses can reach up to 36%. Thus, the study emphasizes the importance of including self-induction in the dynamic model of the harvester. The results obtained are relevant for the development of highly efficient harvesters operating under variable and high-frequency mechanical influences.