Type Of Vibration Energy Harvester Research Articles

Low Frequency High Power Energy Harvester

The vibration energy harvester has become a hot spot because it can supply energy to device without battery. Four types of vibration energy harvesters with different operation modes are introduced in low frequency and high power aspects. They are electromagnetic, magnetostrictive, electrostatic and piezoelectric vibration energy harvester. Their developments are illustrated in detail. Meanwhile, the advantages and disadvantages of the four different structures are compared, and the performances are summarized. Among them, piezoelectric vibration energy harvester was studied the earliest. So, it has better performance and can be used widely.

On adjusting the rotary inertia of a cantilever-type energy harvester for wideband operation

Inertial vibration energy harvesters are effective only when they operate at their natural frequencies. A slight deviation from operation at resonance conditions leads to a substantial reduction in the generated power, which places hurdles for the development of devices that operate across a wide frequency range. To address this issue, we present a vibration energy harvester with a tunable natural frequency. Frequency adjustment in a cantilever-type energy harvester is achieved by varying the rotary inertia of the beam through changing the angular position of a rotatable mass mounted at its tip. The mass is driven by a beam-mounted servomotor which controls its angular position about an axis normal to the beam’s mid-plane, thereby varying the effective mass moment of inertia. In this arrangement, the power required for frequency adjustment is kept to a minimum, since no mechanical straining forces are applied on the beam, and power is only needed when the motor turns to adjust the orientation of the tuning mass. A frequency tuning algorithm is developed to keep the beam operating at resonance. The algorithm relies on information gathered by an infrared sensor/receiver module that detects the prevailing frequency of vibration by a microprocessor and drives the servomotor in accordance with a lookup table that relates natural frequency with angular position of the motor. An analytical model is developed to predict the system dynamics and the variation in natural frequency in terms of the various design parameters. While the proposed design is applicable to various types of vibration energy harvesters, an electromagnetic prototype is presented to verify the concept. Findings of the theoretical model are verified experimentally.

Non-linear dynamics of a vibration energy harvester by means of the homotopy analysis method

This article reports on the modelling and experimental validation of a vibration energy harvesting approach that uses a permanent-magnet/ball-bearing arrangement and a wire-coil transducer. The harvester’s behaviour is modelled using a forced Duffing oscillator modified with quintic non-linearity, and the primary first-order steady-state resonant solutions are found using the homotopy analysis method. These solutions found are shown to compare well with measured ball-bearing displacements and harvested output power and are used to predict the wideband frequency response of this type of vibration energy harvester. A prototype harvester was found to produce a maximum output power of 16.4 mW from a 14.2 Hz, 400 milli-g excitation.

A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data

The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.

An energy harvester combining a piezoelectric cantilever and a single degree of freedom elastic system

This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton's principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for applica- tion to the piezoelectric energy harvester.

Vibration energy harvesting from random force and motion excitations

A vibration energy harvester is typically composed of a spring–mass system with an electromagnetic or piezoelectric transducer connected in parallel with a spring. This configuration has been well studied and optimized for harmonic vibration sources. Recently, a dual-mass harvester, where two masses are connected in series by the energy transducer and a spring, has been proposed. The dual-mass vibration energy harvester is proved to be able to harvest more power and has a broader bandwidth than the single-mass configuration, when the parameters are optimized and the excitation is harmonic. In fact, some dual-mass vibration energy harvesters, such as regenerative vehicle suspensions and buildings with regenerative tuned mass dampers (TMDs), are subjected to random excitations. This paper is to investigate the dual-mass and single-mass vibration harvesters under random excitations using spectrum integration and the residue theorem. The output powers for these two types of vibration energy harvesters, when subjected to different random excitations, namely force, displacement, velocity and acceleration, are obtained analytically with closed-form expressions. It is also very interesting to find that the output power of the vibration energy harvesters under random excitations depends on only a few parameters in very simple and elegant forms. This paper also draws some important conclusions on regenerative vehicle suspensions and buildings with regenerative TMDs, which can be modeled as dual-mass vibration energy harvesters. It is found that, under white-noise random velocity excitation from road irregularity, the harvesting power from vehicle suspensions is proportional to the tire stiffness and road vertical excitation spectrum only. It is independent of the chassis mass, tire–wheel mass, suspension stiffness and damping coefficient. Under random wind force excitation, the power harvested from buildings with regenerative TMD will depends on the building mass only, not on the parameters of the TMD subsystem if the ratio of electrical and mechanical damping is constant.

102 圧電コンポジットを利用した振動発電装置のエネルギー変換効率に関する考察(セッション1 モデル解析・設計)

Authors have proposed a cantilever type of vibration energy harvester with piezocomposite for vibration condition monitoring applications of rotating machinery. Proposed energy harvester consisted of Macro-Fiber Composite (MFC) actuators in bimorph configuration. The dynamics of the vibration energy harvester can be modeled as a single degree-of-freedom, spring-mass-damper system with base excitation due to unbalance response of rotating machinery. Considering the electric circuit connected to the MFC, the equivalent two degree-of-freedom model is obtained. In this study, the energy balance equation is derived. The efficiency of vibration energy transfer to the electrical resistive load of the circuit is estimated by using the derived energy balance equation. The estimated generated maximum AC power is 105.3(μW) with the electrical resistive load 112.8(kΩ) at the resonant frequency of 26.25(Hz) under the excitation amplitude level 0.71(mm/s rms). It indicates that the impedance matching between MFC actuators and the electrical resistive load is effective for maximizing the AC power transfer of the vibration energy harvester. At this condition, input vibration power is calculated as 727(μW) from the energy balance equation, and then the efficiency of vibration energy transfer to the load is estimated as 17%.