Frequency Tuning of a Nonlinear Electromagnetic Energy Harvester

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Longhan Xie ◽  
Ruxu Du
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Frequency Tuning ◽  
Nonlinear Behavior ◽  
Stretch Ratio ◽  
Electromagnetic Energy ◽  
Elastic Strings ◽  
Simulation And Experiment ◽  
Frequency Tunable

This paper investigates a frequency-tunable nonlinear electromagnetic energy harvester. The electromagnetic harvester mainly consists of permanent magnets supported on the base to provide a magnetic field, and electrical coils suspended by four even-distributed elastic strings to be an oscillating object. When the base provides external excitation, the electrical coils oscillate in the magnetic field to produce electricity. The stretch length of the elastic strings can be tuned to change their stretch ratio by tuning adjustable screws, which can result in a shift of natural frequency of the harvester system. The transverse force of the elastic strings has nonlinear behavior, which broadens the system's frequency response to improve the performance of the energy harvester. Both simulation and experiment show that the above-discussed electromagnetic energy harvester has nonlinear behavior and frequency-tunable ability, which can be used to improve the effectiveness of energy harvesting.

scholarly journals Topology Selection and Parametric Design of Electromagnetic Vibration Energy Harvesters by Combining FEA-in-the-Loop and Analytical Approaches

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 627 ◽  
Author(s):  
Seong-yeol Yoo ◽  
Young-Woo Park ◽  
Myounggyu Noh
Keyword(s):  
Output Power ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Electromagnetic Energy ◽  
Vibration Energy ◽  
Maximum Output ◽  
Primary Concern ◽  
Energy Harvesters ◽  
Analytical Approaches

Electromagnetic energy harvesters have been used to capture low-frequency vibration energy of large machines such as diesel generators. The structure of an electromagnetic energy harvester is either planar or tubular. Past research efforts focus on optimally designing each structure separately. An objective comparison between the two structures is necessary in order to decide which structure is advantageous. When comparing the structures, the design variations such as magnetization patterns and the use of yokes must also be considered. In this study, extensive comparisons are made covering all possible topologies of an electromagnetic energy harvester. A bench mark harvester is defined and the parameters that produce maximum output power are identified for each topology. It is found that the tubular harvesters generally produce larger output power than the planar counterparts. The largest output power is generated by the tubular harvester with a Halbach magnetization pattern (94.7 mW). The second best is the tubular harvester with axial magnetization pattern (79.1 mW) when moving yokes are inserted between permanent magnets for flux concentration. When cost is of primary concern, the tubular harvester with axial pattern may become a best option.

scholarly journals Frequency Tuning Characteristics of a High-Power Sub-THz Gyrotron with Quasi-Optical Cavity

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 526
Author(s):  
Xiaotong Guan ◽  
Jiayi Zhang ◽  
Wenjie Fu ◽  
Dun Lu ◽  
Tongbin Yang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Power ◽  
Frequency Tuning ◽  
Optical Cavity ◽  
Separation Distance ◽  
Center Frequency ◽  
Broad Bandwidth ◽  
Particle In Cell ◽  
Power Frequency ◽  
Frequency Tunable

Motivated by some emerging high-frequency applications, a high-power frequency-tunable sub-THz quasi-optical gyrotron cavity based on a confocal waveguide is designed in this paper. The frequency tuning characteristics of different approaches, including magnetic field tuning, mirror separation adjustment, and hybrid tuning, have been investigated by particle-in-cell (PIC) simulation. Results predict that it is possible to realize a smooth continuous frequency tuning band with an extraordinarily broad bandwidth of 41.55 GHz, corresponding to a relative bandwidth of 18.7% to the center frequency of 0.22 THz. The frequency tunability is provided by varying the separation distance between two mirrors and correspondingly adjusting the external magnetic field. During the frequency tuning, the output power remains higher than 20 kW, which corresponds to an interaction efficiency of 10%. Providing great advantages in terms of broad bandwidth, smooth tuning, and high power, this research may be conducive to the development of high-power frequency-tunable THz gyrotron oscillators.

Combined Finite Element Method (FEM) and Network Simulation of a Nonlinear Electromagnetic Energy Harvester

2020 ◽  
Author(s):  
Maxim Germer ◽  
Uwe Marschner ◽  
Andreas Richter
Keyword(s):  
Finite Element ◽  
Energy Storage ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Network Modeling ◽  
Electromagnetic Energy ◽  
Capacitive Energy Storage ◽  
Interface Circuit ◽  
Modeling Methods ◽  
Voltage Doubler

Abstract Combined finite element and network modeling methods provide a time efficient instrument to simulate multi-physics systems. In this work, the Combined Simulation is applied to a nonlinear electromagnetic energy harvester with electrical interface circuit and capacitive energy storage. The energy harvester consists of two cylindrical permanent magnets placed in a cylinder with opposite directions to each other, whereas one magnet is fixed and the other magnet is freely movable in the vertical direction within the cylinder. A coil surrounds the cylinder and transforms the magneto-mechanical energy into electrical energy by means of electromagnetic induction. An external force with a certain wave-form excites the system. Finite element and network modeling methods are combined to determine concentrated and distributed network parameters and to describe the nonlinear system as an equivalent circuit, whereas Finite element modeling of the two permanent magnets reveals the repulsive force at different distances. The position-dependent electromagnetic coupling coefficient is employed by calculating the linked magnetic flux gradient. The system performance, including the interface circuit and an energy storage component, is then predicted using the numerical network simulator LTspice. A voltage doubler is used to charge a capacitor and compared with a one-way and two-way rectifier. The voltage doubler shows the best results and charges the capacitor to the highest voltage. The presented method helped to understand the overall system behavior. Physical quantities can be quickly determined in the network. The method can be applied to other multi-physics systems and to more complex interface circuits, easily.

scholarly journals Analysis of vibration energy harvester with magnetic spring

2018 ◽  
Vol 19 ◽  
pp. 01030
Author(s):  
Marcin Kulik ◽  
Rafał Gabor ◽  
Mariusz Jagieła
Keyword(s):  
Magnetic Field ◽  
Computer Simulation ◽  
Resonance Frequency ◽  
External Force ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Magnetic Interaction ◽  
Vibration Energy ◽  
Vibration Energy Harvester ◽  
Numerical Optimisation

In paper an electromagnetic energy harvester with two fixed permanent magnets and one moving suspended vertically by the magnetic interaction between them. The external force imposed on the system causes displacement of the magnet whose magnetic field induces emf in the coil wound around it. In order to obtain the resonance frequency around 25 Hz, the numerical optimisation was carried out. The measured frequency characteristics of the manufactured system compare well with results of computer simulation.

Switching damping for a frequency-tunable electromagnetic energy harvester

2015 ◽  
Vol 234 ◽  
pp. 311-320 ◽  
Author(s):  
B.L. Ooi ◽  
J.M. Gilbert ◽  
A. Rashid A. Aziz
Keyword(s):  
Energy Harvester ◽  
Electromagnetic Energy ◽  
Frequency Tunable
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