Electronic interface for Piezoelectric Energy Scavenging System

The paper focuses on an electronic interface for systems, called Piezoelectric energy scavenging systems (PESS), which convert the energy of mechanical vibrations into electrical energy using a piezoelectric transducer. The output of the transducer is a strong and irregular function of time hence, to obtain a suitable supply source, an AC-DC conversion is needed. Classical rectifiers (half/full bridge or voltage doubler) with an output storage capacitor do not fit very well, since they work as peak detectors, converting only input voltages which are higher than their output voltage. The paper shows an electronic interface which is able to efficiently harvest the energy associated to the randomic voltage waveform delivered by a piezoelectric transducer. Its working principle is based on an inductive step-up converter; an active driving circuit is used to set the phases of the converter. The energy is stored into a capacitor which is also used to supply the active elements of the step-up converter, realizing a completely autonomous energy scavenging system. For this reason the whole circuitry has been designed with a very low-power consumptions, about 700 nA. A prototype was diffused in 5 V CMOS STMicroelectronics technology and measurements showed its effectiveness.