Ambient vibration energy harvesters: A review on nonlinear techniques for performance enhancement

Energy generation in a hybrid harvester under harmonic excitation

Energy harvesting from chaos in base excited double pendulum

A concept of non-linear electromagnetic system with the rotational magnetic pendulum for energy harvesting from mechanical vibrations was presented. The system was stimulated by vertical excitation coming from a shaker. The main assumption of the system was the montage of additional regulated stationary magnets inside coils creating double potential well, and the system was made with a 3D printing technique in order to avoid a magnetic coupling with the housing. In validation process of the system, modelling of electromagnetic effects in different configurations of magnets positions was performed with the application of a finite element method (FEM) obtaining the value of magnetic force acting on the pendulum. A laboratory measurement circuit was built and an experiment was carried out. The voltage and power outputs were measured for different excitations in range of system operational frequencies found experimentally. The experimental results of the physical system with electrical circuit and numerical estimations of the magnetic field of a stationary magnet’s configuration were used to derive a mathematical model. The equation of motion for the rotational pendulum was used to prove the broadband frequency effect.

Modelling of Electromagnetic Energy Harvester with Rotational Pendulum Using Mechanical Vibrations to Scavenge Electrical Energy

Pumping electrons from chemical potential difference

Multiple energy harvesters in a single device has become important to harvest enough power for sensors. In such situation presence of mistuning may change the performance of the overall system. This paper studies the issue of presence of mistuning in such system and also extend the study to performance evaluation when mechanically coupling is present between the multiple harvesters. A simple case of two pendulums in a same frame is analysed for electromagnetic energy harvesting. Experiments are carried out to support the numerical evaluation. The study limits its observations to low frequency and low amplitude motions. The observation made are very interesting and intricate.

Analysis of energy harvesting from multiple pendulums with and without mechanical coupling

This article investigates an array of pendulums as a potential broadband energy harvester. Closed form expression of the total power is analytically obtained. Effect of parameters on the total power harvested and on frequency band of the harvested power is accessed numerically. Finally experiments are carried out for arrays with two to five pendulums, which strongly supports the numerical observations. Different configurations are studied; (a) pendulums in the array are independent of each other, (b) pendulums are coupled using springs in between. The effect of mechanical grounding, where in the extreme pendulums are connected to the support through a spring, is also investigated. Observations show that array of coupled pendulums with mechanical grounding increased the bandwidth of harvesting frequency. The bandwidth and the total power harvested saturates with the number of pendulums.

Broadband energy harvesting with mechanically coupled harvesters

A low frequency magneto-mechanically coupled energy harvesting system is proposed to increase the power magnitude and bandwidth simultaneously. The system consists of two pendulums that are magnetically and mechanically coupled. The analytical formulation for the coupled system is developed based on the extended Lagrangian formulation. The experimental and simulated results are reported. The results exhibiting the benefits of magneto-mechanical coupling are reported. The experiments show an increment of 30.69% in the power magnitude and 100% enhancement in the bandwidth when compared to independent harvesters even at a low amplitude of excitation. Moreover, Chaos is observed at low frequency and at a low amplitude, which tends to provide larger bandwidths with more power.

Magneto-mechanically coupled electromagnetic harvesters for broadband energy harvesting

Analysis and experiment of magneto-mechanically coupled harvesters

In this research energy harvesting from near periodic structure is discussed. The near periodic system consists of two pendulums connected using a common linear spring. Mistuning in the simple coupled pendulum system is achieved by varying the length of one of the pendulums. Effect of this mistuning on amount of energy harvested is developed analytically and numerically. This will be discussed in this paper and at the same time effect of harvesting on mistuning will be presented. It is shown that with a proper electrical damping, optimal power can be obtained and effect of mistuning can be minimized. Same analysis is carried out with energy harvesting from both the pendulums. In case of harvesting from both the pendulums the harvesting bandwidth is increased and electrical damping required to minimize mistuning is more than that in case of harvesting with mistuned pendulum alone.

P. V. Malaji

Papers

Analysis of energy harvesting from multiple pendulums with and without mechanical coupling

Broadband energy harvesting with mechanically coupled harvesters

Magneto-mechanically coupled electromagnetic harvesters for broadband energy harvesting

Analysis and experiment of magneto-mechanically coupled harvesters

Energy Harvesting from Near Periodic Structures