Broadband electromagnetic vibration energy harvesting system for powering wireless sensor nodes

Abstract

This paper reports the design of an electromagnetic vibration energy harvesting system that provides high power density and broad bandwidth. The ‘double cell’ harvester was chosen as the generator for this system. In order to harvest power over a broad range of frequencies, four ‘double cell’ harvesters with varying resonances were incorporated in the system architecture. The average AC to regulated DC power conversion efficiency across the 4 Hz bandwidth was 78%, which is one of the highest reported magnitudes for an electromagnetic vibration harvesting system. The magnetic flux density variation within the double cell array was modeled using the finite element method and compared to a single cell with equivalent tip mass and magnet volume. The double cell array was found to generate a similar magnitude of power to a single cell but three times higher bandwidth. The average generator conversion efficiency for the double cell array was 45.3%, which approaches the maximum theoretical limit of 50%.

Synchronicity and pure bending of bimorphs: a new approach to piezoelectric energy harvesting

“…Recently, the response bandwidth of vibrational harvesters has attracted considerable interest: since environmental vibrations may fall over a wide range of frequencies, harvesting effectiveness can be increased with wideband devices. An array of beams, each with its own natural frequency and together covering the desired bandwidth, has been used in several studies [5,6]. Frequency tuning has been demonstrated by changing the stiffness of the cantilevered beam by exploiting magnetic interaction [7].…”

3D, wideband vibro-impacting-based piezoelectric energy harvester

“…A typical vibration energy harvester normally uses piezoelectric, electromagnetic, electrostatic, magnetoelectric or triboelectric transduction mechanisms. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] However, regardless of the transduction mechanisms and novel structures, most devices suffer from a series of limits, such as a narrow working bandwidth and low output power in various motion directions. Thus, these harvesters are not effective in scavenging energy from the external vibrations with time-variant or three-dimensional (3D) motion directions, such as ocean wave, wind and human motion.…”

Analysis of multi-direction low-frequency vibration energy harvester using diamagnetic levitation

“…Considerable amount of publications have discussed micro electromagnetic energy harvester. In general, current micro-vibration energy harvesters based on electromagnetic mechanism fall into the following types: moving part supported by a spring [7][8][9][10], proof mass fixed on a diaphragm [11][12][13][14], cantilever with proof mass [15][16][17][18], and levitated moving part [19][20][21][22][23]. There is considerable energy loss in micro-energy harvester with mechanical spring, diaphragm or cantilever due to mechanical contact, which limits the energy harvesting efficiency of the devices.…”