Single-Supply Pre-Biasing Circuit for Low-Amplitude Energy Harvesting Applications

Harvesters utilizing piezoelectricity as the transduction method have advantages over other designs in that the transducer output voltage and current tend to be in a more favourable range for input to a power electronic interface. However, typical devices often operate significantly below their fundamental maximum power because the transducer is unable to provide enough electrical damping. Consequently, circuits have been developed that allow increased damping, such as the SSHI techniques proposed by Guyomar et al., and the pre-biasing technique proposed by us. However, the performance of these circuits suffers significantly at low input voltages, which may occur at low harvester input excitation amplitudes. We present here a new circuit termed single-supply pre-biasing which is able to increase the power output from a piezoelectric harvester to a greater extent than previously possible at both low and high input voltages.