Shunt-diode rectifier: a new scheme for efficient piezoelectric energy harvesting

Abstract

This paper highlights the interest of shunt-diode rectifiers to optimize the performances of piezoelectric vibration energy harvesters based on linear load adaptation. It provides, for the first time, a full analytical study of the input power and frequency bandwidth of such a system. We show that this architecture is well-suited for piezoelectric energy harvesting. In the presented approach, a so-called shunt diode is connected across the electrodes of the piezoelectric transducer, which makes the piezoelectric voltage unidirectional instead of alternating. Thus, DC–DC converters usually used for power optimization can be directly connected to the transducer. We show that weakly-coupled linear inertial piezoelectric energy harvesters generate higher power when connected to a shunt-diode rectifier than to a bridge rectifier. Moreover, the frequency bandwidth is enlarged by the use of the single-diode shunt rectifier, especially for strongly-coupled piezoelectric generators. The proposed architecture is also interesting for low piezoelectric voltages, at which voltage drops across the diodes used for AC–DC conversion critically degrade the power efficiency. Experimental results validate the presented analytical study and highlight the higher efficiency of the shunt-diode rectifier circuit. Compared to a standard bridge rectifier architecture, we demonstrate an increase of +43% output power on a weakly-coupled generator and an increase of +5% bandwidth on a strongly-coupled generator.