Hybrid Vibration Energy Harvester Research Articles

Energy generation through a hybrid energy harvester under random excitation

This manuscript analyses a multi-frequency based coupled piezo-electromagnetic hybrid vibration energy harvester. Most of the energy harvesting devices discussed in the literature are based on the assumption that the base excitation is harmonic. However, in general, energy harvesting devices are deployed in an ambient environment, which is random in nature. Hence, in this regard, the manuscript discusses the power harvesting capabilities of the hybrid energy harvester under random base excitation using analytical and experimental studies. Acceleration with band limited Gaussian noise has been provided as an input to the base of the harvester. Comparative studies are also made to understand the performance of the hybrid harvester over conventional standalone piezoelectric and electromagnetic harvesters under the same support excitation. Thus, the novelty of the present work is to analyse a novel design of a hybrid harvester to improve harvesting performance across a wide range of frequencies under random base excitation compared to conventional harvesters. The results demonstrate that the proposed hybrid energy harvester can yield sufficient power over a wide range of frequencies. In addition, parametric studies have also been performed to characterize the system parameters in order to enhance the performance of the harvester. Studies show that the harvested power can be enhanced by maximizing the values of mass ratio, frequency ratio, non-dimensional electromechanical coupling coefficient and minimizing the values of structural damping ratios. Finally, practical applications of the proposed device have also been reported.

A hybrid vibration energy harvester with integrated piezoelectric and electrostatic devices

In recent years, energy harvesting technology has become a promising power supply method for low-power wireless sensor nodes. According to the application requirements of energy acquisition, a piezoelectric and electrostatic hybrid vibration energy harvester (HVEH) is proposed in this paper. Compared with other vibration energy harvesters, the proposed hybrid harvester is easier to miniaturize and integrate into a MEMS. The electromechanical coupling model of the hybrid harvester is established. The optimal design of the proposed harvester is carried out based on numerical simulation. The optimal matching impedance of piezoelectric and electrostatic modules are calculated based on numerical simulation and validated through experiments, which are 80–90 kΩ and 15–20 MΩ, respectively. The output power of the HVEH is increased by 0.04%, 0.08%, 0.102%, and 0.097%, when the excitation acceleration is 0.1 g, 0.15 g, 0.2 g, and 0.25 g, respectively, compared with the single piezoelectric module.

Guest Editorial: Polymer electrets and ferroelectrets

Guest Editorial: Polymer electrets and ferroelectrets

A floating piezoelectric electromagnetic hybrid wave vibration energy harvester actuated by a rotating wobble ball

This paper presents a floating piezoelectric electromagnetic hybrid wave vibration energy harvester actuated by a rotating wobble ball. The kinematic equation of the rotating wobble ball under the influence of the wave is established by simplifying the ocean wave model. One merit of the proposed harvester is that it can harvest wave vibration energy via a frequency up-conversion mechanism. The vibration energy of a wave is converted into electrical energy by the electromagnetic generator (EMG) and the piezoelectric ceramic transducer (PZT). Low-frequency vibration energy is converted into the high frequency vibration of the PZTs using frequency up-conversion mechanism. The results show that the maximum power generated by the proposed hybrid energy harvester is 21.95 mW when the external frequency of the wave is 1.4 Hz. Additionally, two PZTs and the EMG successfully output about 11.26 mW of power to light up LEDs throughout a test of low-power electronics. The results demonstrate that low-frequency wave vibrations can be efficiently harvested using the proposed hybrid vibration energy harvester.

Frequency‐tunable resonant hybrid vibration energy harvester using a piezoelectric cantilever with electret‐based electrostatic coupling

AbstractHybrid vibration energy harvesting technology converts vibration energy into electricity using multiple transduction mechanisms to improve output power. A frequency‐tunable resonant hybrid vibration energy harvester using a piezoelectric cantilever with electret‐based electrostatic coupling is proposed in this article. The electrostatic coupling including electrostatic force coupling and electrical damping coupling is introduced by an electret film placed below the cantilever, where the electrostatic force acting on the cantilever realises a tunable resonant frequency and additional electrical damping boosts power output. A coupling electromechanical model is derived using Euler–Bernoulli beam theory and Kirchhoff's law. By investigating the static and dynamic stability of cantilever, the maximum electret surface potential is defined to prevent the pull‐in phenomenon. The damping of the device is evaluated, and the optimal electret surface potential is determined to obtain the matching of the electrical and mechanical damping for maximum power output. The resonant frequency of hybrid vibration energy harvester can be adjusted in range of 176.1 rad/s by changing the electret surface potential and resistive load. The experimental output power of hybrid vibration energy harvester was 5.2 μW, 27.4 times higher than that of the individual piezoelectric generator. The proposed hybrid vibration energy harvester exhibits a promising potential to power microelectronic devices and wireless sensor network node.

Hybrid acoustic, vibration, and wind energy harvester using piezoelectric transduction for self-powered wireless sensor node applications

Energy harvesters are considered to be a promising solution for long lasting operation of wireless sensor nodes, moreover, make these power-sustainable in hazardous, implantable, remote, harsh, embedded, and abandoned environments where frequent battery replacement is a challenge. Existing energy harvesters utilize only one or two ambient energy sources, however, in this paper, we developed a novel piezoelectric-based energy harvester that converts three ambient energies (acoustic, vibration, and wind) simultaneously into electrical energy. The developed harvester comprises a Helmholtz resonator, a unimorph piezoelectric composite plate, and a cambered aerofoil connected with a piezoelectric plate using a base support. Acoustic, vibration, and wind induced deformation in the harvester’s piezoelectric plate and intrun electrical energy is produced based on piezoelectric phenomena. The harvester showed two peaks (at 802 and 1417 Hz frequencies) when subjected to a forward frequency sweep (FFS) which corresponds to its resonant frequencies. Under resonance, in the acoustic and vibrations environment, the harvester produced a maximum power of 210.6 µW, and 1.38 mW on excitation at 130 dB sound pressure level (SPL) and 0.8 g base acceleration, respectively. Furthermore, the harvester produced maximum power of about 285 µW when exposed to 8 m/s wind speed. The developed harvester can be a potential power source for self-powered wireless sensors used for the structural health monitoring of bridges, tall buildings, and railway tracks.

Dynamics of a tri-stable hybrid energy harvester under narrow-band random excitation

This paper aims to reveal the stochastic dynamics of a tri-stable piezoelectric–electromagnetic hybrid vibration energy harvester (HVEH) driven by narrow-band random excitation for purpose of enhancing the energy harvesting performance. The steady-state solutions of the electromechanical coupling tri-stable HVEH in the symmetric case are derived by the method of multiple scales, which are verified by Monte Carlo simulations. Results show that the stochastic jump phenomenon exists and the operational bandwidth of HVEH can be extended. The effects of narrow-band random excitation, critical system parameters and asymmetric potential function on stochastic dynamics are discussed. It is found that the miniaturization design of the HVEH can be optimized and the mean output power can be improved by selecting appropriate system parameters. Moreover, compared with the symmetric structure, in the case of the same highest potential-well depth, the asymmetric structure with a smaller potential-well distance is beneficial for HVEH to achieve high-energy inter-well oscillation under low-level excitation. Meanwhile, the power conversion efficiency reaches the maximum in the high-energy inter-well oscillations triggered at the critical excitation amplitude.

Functionalization of Internal Resonance in Magnetically Coupled Resonators for Highly Efficient and Wideband Hybrid Vibration Energy Harvesting.

The functionalization of internal resonance (IR) is theoretically and experimentally demonstrated on a nonlinear hybrid vibration energy harvester (HVEH) based on piezoelectric (PE) and electromagnetic (EM) transductions. This nonlinear phenomenon is tuned by adjusting the gaps between the moving magnets of the structure, enabling 1:1 and 2:1 IR. The experimental results prove that the activation of 2:1 IR with a realistic excitation amplitude allows the improvement of both the frequency bandwidth (BW) and the harvested power (HP) by and , respectively compared to the case away from IR. These remarkable results open the way towards a very large scale integration of coupled resonators with simultaneous internal resonances.

An annular tubular wearable piezoelectric-electromagnetic hybrid vibration energy harvester driven by multi magnetic beads

Wearable devices are widely applied because of the rapid development of semiconductor devices and integrated circuit technology. People hoped to enhance their senses through various wearable devices. However, the application is currently limited by the operating time of electrochemical batteries. This paper presents an annular tubular wearable piezoelectric-electromagnetic hybrid vibration energy harvester driven by multi magnetic beads for harvesting energy from the arm swing motion. The structure consists of a piezoelectric beam, magnetic beads and a set of coils. Specifically, piezoelectric energy harvesting (PEH) converts vibration energy into electrical energy by using a new macro-fiber composite (MFC). Magnetic beads and coils form an electromagnetic energy harvester (EMEH).Two energy harvesting units are coupled by magnetic beads. The magnetic beads can not only induce the coil to generate electrical energy, but also excite the piezoelectric beam. Two conversion mechanisms extract energy simultaneously through one excitation.Experimental results show that the device can harvest the vibration energy generated by human activity under different types of human motion, such as slow walking, fast walking and running. The integration between PEH and EMEH not only extends the operating bandwidth, but also makes it easy for ultra-low frequency energy harvesting. The prototype harvester that could power a number of portable electronic devices shows great potential.

A study of a new hybrid vibration energy harvester based on broadband-multimode

To improve the energy conversion efficiency and working frequency bandwidth of a single frequency piezoelectric vibration energy harvester, a new type of hybrid vibration energy harvester is developed which is combined with the mechanism of piezoelectric and electromagnetic energy conversion. The system comprises of a PZT cantilever beam, an elastic suspended magnetic mass, a magnet block attached to the end of the cantilever beam and a resonator. The addition of resonator can not only increase the mode, but also adjust the frequency of harvester flexibly. Nonlinear magnetic force of magnet block not only broadens the frequency band and improves the output performance of the system, but also changes the resonant frequency to make the harvester have better adjustable performance. On this basis, an improved electromechanical coupled analytical model of continuum is proposed which can be solved by the Runge-Kutta algorithm and the influence of different factors (the mass and spring stiffness of the resonator, as well as the electromechanical coupling coefficient, electromagnetic coupling coefficient, magnet mass and magnetic flux) on the output are analyzed. According to the prototype of the vibration energy harvester developed, an experimental system was built. The performance of the independent and hybrid energy harvesters is evaluated by experimental and analytical methods. The peak output voltage of the piezoelectric part was about 4 times that of the electromagnetic part. The peak output current of the electromagnetic part is about 30 times that of the piezoelectric part. The study results show that the proposed new hybrid vibration energy harvester can achieve a wider frequency range and multimodal vibration energy harvesting. In addition, the bandwidth and power of the harvester can be dynamically adjusted by changing the resonator or electromechanical coupling coefficient, and the bandwidth of the harvester can also be adjusted by changing the quality and characteristics of the magnet.

A silicone based piezoelectric and electromagnetic hybrid vibration energy harvester

This paper describes the investigation of a novel low-cost silicone-based hybrid vibration energy harvester (SHVEH) for converting machine vibrations into useful electrical power for wireless sensor nodes. Due to a novel fabrication technique, the harvester has the benefit of incorporating two transduction mechanisms (electromagnetic and piezoelectric) into a single silicone housing for improved output power. In the devised fabrication technique, water-soluble tablets are used to develop a cavity inside the silicone structure for an embedded magnet to vibrate in. The developed device was characterized inside the lab at different acceleration levels. The SHVEH was found to be capable of delivering a combined output power of 1.12 mW and a power density of 52 µW cm−3. The SHVEH was able to deliver maximum open circuit voltages of 3 V and 28 mV AC via the piezoelectric and electromagnetic portions, respectively, at a resonant frequency of 110 Hz. Furthermore, after connecting the SHVEH to rectifier circuitry, the DC voltage levels obtained were 3.5 V and 35 mV from the piezoelectric and electromagnetic portions, respectively.

Colored Lévy Noise-Induced Stochastic Dynamics in a Tri-Stable Hybrid Energy Harvester

Abstract The piezoelectric and electromagnetic hybrid vibration energy harvester (HVEH) has proven to be a favorable option to deal with the low power generation issue and overcome the drawbacks of each individual transduction mechanism. Besides, colored Lévy noise consisting of small perturbations, large jumps, and correlation time turns out to be a relatively suitable tool for describing the complex environments. For the purpose of enhancing the harvesting performance of HVEH, the stochastic dynamics induced by colored Lévy noise in a tri-stable HVEH is mainly investigated in this paper. The stationary probability density, the largest Lyapunov exponent, the signal-to-noise ratio, and the mean harvested power are calculated to explore the stochastic dynamics of system, such as the stochastic response, the stochastic stability, the stochastic resonance (SR), and the energy harvesting performance. The results show that the colored Lévy noise can induce stochastic P-bifurcation, D-bifurcation, and SR phenomenon. In particular, the comparisons between colored Lévy noise and colored Brownian noise in dynamics and harvesting performance are also discussed in detail. It is found that the colored Lévy noise can make a greater contribution than colored Brownian noise in the effective voltage and help to improve the mean harvested power through the SR effect.

Research on the Self-powered Wireless Sensor Micro-system Based on the Hybrid Vibration Energy Harvester

Research on the Self-powered Wireless Sensor Micro-system Based on the Hybrid Vibration Energy Harvester

Probabilistic response of a fractional-order hybrid vibration energy harvester driven by random excitation.

The stochastic response of a fractional-order hybrid vibration energy harvester is investigated in this paper. Equivalent system can be derived by the variable transformation. Then, the probability density functions of mechanical states are obtained by the stochastic averaging technique. The good agreement between numerical simulation and analytical results demonstrates the effectiveness of the proposed method. Mean square voltage, mean square current, and mean output power are presented to illustrate the device output performance. Results imply that the hybrid vibration energy harvesting system can generate higher mean output power than that from a separate piezoelectric system and an electromagnetic system.

High Performance Hybrid Piezoelectric-Electromagnetic Energy Harvester for Scavenging Energy From Low-Frequency Vibration Excitation

There are many difficulties in the power supply of the wireless monitoring system for coal mine mechanical equipment. Vibration energy scavenging is a green and effective way to solve this problem considering the intense and continuous vibration of coal mechanical equipment. In this paper, a novel hybrid vibration energy harvester was designed and manufactured, which combined electromagnetic and piezoelectric transduction units. Vibration drives the two units to move in the vertical and horizontal directions to realize the energy conversion. The mathematic model was built to calculate and predict the performance while the simulation on the distribution of magnetic field and piezoelectricity potential provided the details in the design. Besides, the output signal generated by the vibration excitation of the electromagnetic unit, piezoelectric unit and the whole energy harvester were studied simultaneously. Moreover, the resonance frequency was tested to be 14Hz, and the optimum matching impedance was measured to be 1kΩ and 10kΩ with the parallel and series connection of PH and EH, respectively. The maximum output power of the HPEH with the parallel connection pattern can reach 80.10mW at the acceleration of 2g. In the application experiment, the HPEH can facilely light up 120 LEDs and supply stable power for the electronics and sensors.

Design and Analysis of a Hybrid Solar and Vibration Energy Harvester

Abstract The performance of the small-scale stand-alone energy harvesters can be improved by implementing a hybrid energy harvesting technique. This paper aims at presenting the design and characterization of a hybrid energy harvester that can simultaneously harvest energy from mechanical vibration and solar radiation by combining piezoelectric, electromagnetic, electrostatic, and photovoltaic mechanisms. The hybrid device consists of a small high-efficiency solar panel and a bimorph PZT cantilever beam having a cylindrical tip magnet and two sets of capacitors (comb electrodes) attached on two sides of an ASTM 6061 T-6 Aluminum substrate. All the transducing sections of the configuration are interconnected by a smart hybrid electric circuit having a common optimum load resistance, an energy storage, and a microcontroller to generate and store combined power output when subjected to transverse vibration and solar radiation. The initial bias-voltage input required for the electrostatic mechanism is either obtained from the photovoltaic system or taken from the storage through the microcontroller. Results for the maximum power output are obtained at the fundamental resonance frequency of the vibrating cantilever beam. As the hybrid design allows a combined power harvesting method, more power is generated with better conversion efficiency than those obtained by stand-alone mechanisms. In addition to the power calculation, the study includes a stress and fatigue analysis of the cantilever beam using the finite element method to investigate the stress-life criteria of the hybrid structure.

Dynamics and performance evaluation of a novel tristable hybrid energy harvester for ultra-low level vibration resources

To improve the efficiency of energy harvesting from external ultra-low level vibration resources, this article presents a novel tristable hybrid vibration energy harvester using geometric nonlinearity technique to tuning the resonant frequency and broadening the bandwidth. Based on a simple snap-through spring-mass system, it is composed of a piezoelectric ceramics, two ring permanent magnets and a central inertial mass. The device was designed as harvesting energy from low and ultra-low level vibration resources by exploring structural benefits and nonlinear characteristics. The governing electromechanical coupling equations of motion are derived, and a transformation is performed to decouple the equations. The presented device has different nonlinear stiffness properties of the hardening spring effect, softening spring effect and hardening-softening spring effect, which are ideal for the system to harvest broadband energy and suitable for energy harvesting for changing excitation. Compared with monostable and bistable energy harvesters, the tristable energy harvesting has a wider bandwidth for resonance than the bistable or monostable one to enhance the energy harvesting performance over a broadband ultra-low level frequency region. For ultra-low level stochastic fluctuation, results show that the tristable characteristic can lead to a large response and give out a high harvested power.

Hybrid Vibration Energy Harvester based on Stochastic Resonance

Hybrid Vibration Energy Harvester based on Stochastic Resonance

A tunable broadband magnetoelectric and electromagnetic hybrid vibration energy harvester based on nanocrystalline soft magnetic film

In this paper, a tunable broadband electromagnetic (EM) and magnetoelectric (ME) hybrid vibration energy harvester (HVEH) employing a hybrid transducer and double cantilever to convert low-frequency vibration energy into electrical energy is presented. The electric output performances of the proposed HVEH have been investigated. Compared to single ME or EM vibration energy harvester (VEH), the experiment results show that the proposed HVEH can simultaneously obtain an enhanced output performance including higher power, voltage, current and wide bandwidth. It is found that the output power and resonance frequency of HVEH can be tuned by controlling the FeCuNbSiB layer thickness, turns number and cantilever length, respectively. When FeCuNbSiB layer thickness, cantilever length and turns number is 30μm, 5cm and 750, the optimum output power and effective bandwidth of HVEH achieve 36.8mW and 5.6Hz for an acceleration of 0.75g at frequency of 32Hz, respectively. Remarkably, the proposed HVEH has great potential for its application in wireless sensor networks.

Theoretical and experimental studies on piezoelectric-electromagnetic hybrid vibration energy harvester

In order to improve the performance of vibration energy harvester (VEH), multiple electromechanical transducers based hybrid vibration energy harvester (HVEH) has been proposed by some researchers. In this paper, we focus on the piezoelectric-electromagnetic HVEH and established the theoretical model for the HVEH with Hamilton's principle. The established theoretical model shows that the performance of the HVEH is not equal to the sum of the two stand-alone VEH, and the equivalent electrical damping of the HVEH can also not be directly expressed as the sum of the two equivalent electrical damping of the stand-alone VEH. These are different from the existing theoretical model. To verify the established model, a piezoelectric-electromagnetic HVEH was fabricated and tested. The power output of the fabricated HVEH is 57.24 $$\upmu$$μW. Experimental results show that the power output of the HVEH is less than the sum power output of the two stand-alone VEH, but is higher than power output of any one stand-alone VEH, which is agree with the established theoretical model.