Design, Modeling, and Characterization of a Tubular Linear Vibration Energy Harvester for Integrated Active Wheel System

A major source of electric vehicle energy loss is the vibration energy dissipated by the shock absorbers under irregular road excitation, which is particularly severe when active wheel systems are employed because their greater unsprung mass leads to greater shocks and vibrations. Therefore, a tubular linear energy harvester (TLEH) with a large stroke and low electromagnetic force ripple is designed to convert this vibration energy into electricity. The proposed TLEH employs a slotted external mover with three-phase winding coils and an internal stator with PMs to increase the stroke, adopts a fractional slot-per-pole configuration to reduce its size and improve the winding factor, and realizes significantly reduced cogging force by optimizing the incremental length of the armature core. A finite element model of the TLEH is first verified against a theoretical model and then used to investigate the influences of various road excitation frequencies and amplitudes on the electromotive force (EMF) waveforms and generated power, the efficiency and damping force according to load condition, and the energy recovery and nonlinear electromagnetic force characteristics of the TLEH. A resistance controller is then designed to realize a self-damping electromagnetic suspension. The results indicate that the EMF and the generated power waveforms depend on the excitation frequency and amplitude, the efficiency increases and the damping coefficient decreases with the increasing load resistance.