Maximum Performance of Piezoelectric Energy Harvesters When Coupled to Interface Circuits

Lindsay M Miller,Alwyn D T Elliott,Paul K Wright,Paul D Mitcheson,Igor Paprotny,Einar Halvorsen

doi:10.1109/jsen.2016.2546684

Abstract

This paper presents a complete optimization of a piezoelectric vibration energy harvesting system, including a piezoelectric transducer, a power conditioning circuit with full semiconductor device models, a battery and passive components. To the authors awareness, this is the first time and all of these elements have been integrated into one optimization. The optimization is done within a framework, which models the combined mechanical and electrical elements of a complete piezoelectric vibration energy harvesting system. To realize the optimization, an optimal electrical damping is achieved using a single-supply pre-biasing circuit with a buck converter to charge the battery. The model is implemented in MATLAB and verified in SPICE. The results of the full system model are used to find the mechanical and electrical system parameters required to maximize the power output. The model, therefore, yields the upper bound of the output power and the system effectiveness of complete piezoelectric energy harvesting systems and, hence, provides both a benchmark for assessing the effectiveness of existing harvesters and a framework to design the optimized harvesters. It is also shown that the increased acceleration does not always result in increased power generation as a larger damping force is required, forcing a geometry change of the harvester to avoid exceeding the piezoelectric breakdown voltage. Similarly, increasing available volume may not result in the increased power generation because of the difficulty of resonating the beam at certain frequencies whilst utilizing the entire volume. A maximum system effectiveness of 48% is shown to be achievable at 100 Hz for a 3.38-cm3 generator.

Highlights

E NERGY can be harvested from environmental vibrations using piezoelectric [1], [2], electromagnetic [3], [4], or electrostatic [5] transduction to couple the mechanical and electrical domains
In this paper we present a model that captures the coupled behaviour of a piezoelectric energy harvester and the power conditioning circuitry with full semiconductor device models, allowing optimal system design in piezoelectric energy harvesting for the first time
A framework was developed in order to investigate the full system effectiveness of a piezoelectric harvester coupled to a single-supply pre-biasing (SSPB) circuit and a buck converter, including the semiconductor device models, and a battery, to maximise power generation within a specific volume

Summary

Introduction

E NERGY can be harvested from environmental vibrations using piezoelectric [1], [2], electromagnetic [3], [4], or electrostatic [5] transduction to couple the mechanical and electrical domains. The goal of this study is to determine a piezoelectric energy harvesting system’s maximum power output, and corresponding effectiveness and system parameters as a function of input acceleration, frequency and system volume. The SSPB circuit is used as the power conditioning circuit since it was determined in [16] to be the most efficient implementation to date which performed the needed operations to achieve optimally controlled Coulomb-damping for electrical power extraction. The power required by control circuitry to operate the synchronous switching is not considered in this study This will impact the useful power output from the system, but will not impact the ability to compare the piezoelectric harvester performance with other types of transducers since the power loss for operating control circuitry will be similar for all systems that use synchronously switched circuits. We restrict the analysis to harmonic input vibrations and resonant harvesters operating at resonance

Objectives

Methods

Findings

Conclusion