Resonant electromagnetic vibration harvesters: determination of the equivalent electric circuit parameters and simplified closed-form analysis for the identification of the optimal bridge rectifier DC load

In this paper, the guidelines leading to the identification of the values of the parameters of the equivalent electric circuit of vibration electromagnetic harvesters are identified and discussed. A simplified closed form analysis of the non-linear system composed by a vibration electromagnetic harvester which supplies a DC load by means of a diode bridge rectifier is also presented. Such an analysis clearly puts in evidence that the maximum power which can be extracted by a given vibration harvester (when it supplies the optimal load impedance) is higher than the maximum power which can be extracted by such an harvester when it is cascaded with a diode bridge rectifier which supplies the optimal DC load. The term ‘‘optimal load” identifies in both cases the load in correspondence of which the electric power which is extracted from vibrations attains its maximum value.