Piezoelectric vibration energy harvesting: A connection configuration scheme to increase operational range and output power

For a conventional monolithic piezoelectric transducer (PT) using a full-bridge rectifier, there is a threshold voltage that the open-circuit voltage measured across the PT must attain prior to any transfer of energy to the storage capacitor at the output of the rectifier. This threshold voltage usually depends on the voltage of the storage capacitor and the forward voltage drop of diodes. This article presents a scheme of splitting the electrode of a monolithic piezoelectric vibration energy harvester into multiple ( n) equal regions connected in series in order to provide a wider operating voltage range and higher output power while using a full-bridge rectifier as the interface circuit. The performance of different series stage numbers has been theoretically studied and experimentally validated. The number of series stages ([Formula: see text]) can be predefined for a particular implementation, which depends on the specified operating conditions, to achieve optimal performance. This enables the system to attain comparable performance compared to active interface circuits under an increased input range while no additional active circuits are required and the system is comparatively less affected by synchronized switching damping effect. </jats:p

Self-powered and Self-configurable Active Rectifier Using Low Voltage Controller for Wide Output Range Energy Harvesters

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this recordData availability: All data are provided in full in the results section of this paper.This paper presents a self-configurable and selfpowered active rectifier that operates from 0.25–20 V for energy harvesting applications. The proposed circuit self-startups from a low voltage using a charge pump and amplifies the voltage with a voltage doubler (VD) topology to provide succeeding circuits such as boost converters with a higher voltage. When the voltage of the energy harvester reaches a high threshold, the circuit switches its topology to a full-wave rectifier (FR) that does not amplify the voltage. The start-up circuit can limit its voltage intake to prevent boosting the high voltage, which may damage the whole circuit. Comparators with a maximum operating voltage of 5.5 V used in the implementation of the rectifier are protected by a diode and resistor based circuit. A piezoelectric energy harvester (PEH) that has a wide open-circuit voltage of 0.4–15 V under the acceleration of 0.04–0.3 g was used to test the circuit. The experiment results showed the rectifier can startup from 0.25 V and switch its topology according to the PEH voltage. The voltage and power conversion efficiencies are over 90% in most cases.Engineering and Physical Sciences Research Council (EPSRC)Royal Societ

An Efficient Inductorless Dynamically Configured Interface Circuit for Piezoelectric Vibration Energy Harvesting

Vibration energy harvesting based on piezoelectric materials is of interest in several applications such as in powering remote distributed wireless sensor nodes for structural health monitoring. Synchronized switch harvesting on inductor and synchronous electric charge extraction circuits show good power efficiency among reported power management circuits; however, limitations exist due to inductors employed, adaption of response to varying excitation levels, and the synchronized switch damping (SSD) effect. In this paper, an inductorless dynamically configured interface circuit is proposed, which is able to configure the connection of two piezoelectric materials in parallel or in series by periodically evaluating the ambient excitation level. The proposed circuit is designed and fabricated in a 0.35 μHV CMOS process.The fabricated circuit is cointegrated with a piezoelectric bimorph energy harvester and the performance is experimentally validated. With a low power consumption (0.5 μW), the measured results show that the proposed rectifier can provide a 4.5 × boost in harvested energy compared to the conventional full-bridge rectifier without employing an inductor. It also shows a high power efficiency over a wide range of excitation levels and is less susceptible to SSD.Engineering and Physical Sciences Research CouncilThis is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/TPEL.2016.258775

Energy harvesting from human and machine motion for wireless electronic devices

Published versio

Power electronic interfaces for piezoelectric energy harvesters

Motion-driven energy harvesters can replace batteries in low power wireless sensors, however selection of the optimal type of transducer for a given situation is difficult as the performance of the complete system must be taken into account in the optimisation. In this thesis, a complete piezoelectric energy harvester system model including a piezoelectric transducer, a power conditioning circuit, and a battery, is presented allowing for the first time a complete optimisation of such a system to be performed. Combined with previous work on modelling an electrostatic energy harvesting system, a comparison of the two transduction methods was performed. The results at 100 Hz indicate that for small MEMS devices at low accelerations, electrostatic harvesting systems outperform piezoelectric but the opposite is true as the size and acceleration increases. Thus the transducer type which achieves the best power density in an energy harvesting system for a given size, acceleration and operating frequency can be chosen. For resonant vibrational energy harvesting, piezoelectric transducers have received a lot of attention due to their MEMS manufacturing compatibility with research focused on the transduction method but less attention has been paid to the output power electronics. Detailed design considerations for a piezoelectric harvester interface circuit, known as single-supply pre-biasing (SSPB), are developed which experimentally demonstrate the circuit outperforming the next best known interface's theoretical limit. A new mode of operation for the SSPB circuit is developed which improves the power generation performance when the piezoelectric material properties have degraded. A solution for tracking the maximum power point as the excitation changes is also presented.Open Acces