Optimized piezoelectric transducer-based energy harvesting module, in particular for charging the battery of an implantable medical device such as a leadless autonomous cardiac capsule

Abstract

This module comprises: a circuit for interfacing with the piezoelectric beam of an oscillating pendular unit, outputting a rectified signal comprising a sequence of pulses at a frequency equal to a multiple of the oscillation frequency of the pendular unit; a buffer capacitor charged by the successive pulses outputted by the interface circuit; and a converter regulator adapted to convert a capacitor discharge current into a stabilized power supply voltage, and controlled by a feedback control stage of the Maximum Power-Point Tracking (MPPT) type. A comparator detects the conduction of a blocking diode interposed between the interface circuit and the capacitor, in order to produce a signal representative of the current value of the duty cycle of the detected conduction and non-conduction periods. This signal is compared with a predetermined optimum duty cycle value in order to enable or disable the coupling of the capacitor to the converter regulator so as to control either the capacitor discharge towards an input of the converter regulator, or the continuation of its charging.