The conventional development of tubular generators for applications intended to harvest energy using vehicle suspension systems is faced with the critical challenge of increasing the power harvested for a given space. Conventional optimal designs of machine dimensions have improved both output power and output power density, but the actual values are still relatively small. Recently, we proposed a novel tubular generator structure that combines a mechanical shock absorber and an electrical generator. An innovative permanent magnet structure using both Halbach array and iron spacers (a hybrid-type) was applied. The high relative permeability of the iron material significantly improved the performance of the proposed generator in comparison with conventional models. A prototype was fabricated and experimentally validated via simulation.

Based on the dimensions and thresholds of power and power density of a commercial shock absorber in the Korando car (an SUV branch), a single-phase 8 slot - 8 pole tubular permanent magnet machine was designed and fabricated. The main focus of this study was on the increase of output power in a given space and reduction of the volume. This was successfully solved using a novel structure for a permanent magnet and considering a number of slot-pole combinations. Furthermore, a multi-objective optimization was performed to find the trade-off between various objectives. The experimental results reveal that the proposed machine could possibly regenerate a maximum of 339.95 W and an average of 96.67 W in terms of its output power. Considering the active volume, which includes a permanent magnet, iron core, pure copper, and an electromagnetic air gap, the estimated maximum and average power density were 0.311 and 0.087 W/cm $^3$ , respectively. Despite these satisfactory results, one of the major drawbacks to exploiting this machine is its high electromagnetic force, which causes negative effects on safety and driving comfort. With the aim to commercialize the proposed device, further work will be concentrated on the reduction of electromagnetic force and on performance of the road tests.

This paper presents an optimal design of an exterior permanent magnet (PM) tubular machine for energy harvesting from vehicles suspension systems. By using a hybrid structure, in which, the mechanical damper remains and electrical components are attached to the damper's frame, the damping force and damping coefficient are still ensured while wasted kinetic energy is recovered. To maintain driving comfort and safety, the detent force and electromagnetic force must be minimized. The constraints for dimensions of the exterior PM tubular machine were obtained from an actual shock absorber from a school bus, a large-size vehicle. Different topologies were investigated to maximize the output power and power density, while the electromagnetic force was minimized and negative effects of the initial positions to the machine's performance were mitigated. Finite element analysis showed that maximum and average power from an optimal design were about 210.2 and 103.7 W, respectively. To verify the validity of the design, a prototype was fabricated and tested.

This paper deals with the design of an electromagnetic energy harvesting generator for the suspension system of a sport utility vehicle. The proposed generator is composed of a single coreless type permanent magnet layer, which increases flux density across the coil windings and eliminates flux leakage by using the Halbach PM array, thus improving the machine’s performance, including flux linkage and output power. The goal of the system is to regenerate energy from the kinetic energy of the suspension system of the sport utility vehicle. The proposed generator physically combines electrical and mechanical components, in which permanent magnets, coil windings, and back iron are attached to the body of the shock absorber. The design’s performance was investigated using the finite element method (FEM) and validated by comparison with experimental data.

In this paper, modification of dual-Halbach permanent magnet (PM) array is investigated to improve performance of tubular linear machine, in terms of flux density and output power. Instead of a classical Halbach array with only radial and axial PMs, proposed model involves insertion of mig-magnets, which have magnetized angle shifted from the reference magnetized angles of axial and radial PMs. This structure leads to elimination of flux leakage and concentration of flux linkage in middle of the coil; therefore, the performance of machine is increased.

In this paper, a modification of the dual-segment permanent magnet (PM) Halbach array is investigated to improve the performance of the tubular linear machine, in terms of flux density and output power. Instead of a classical Halbach array with only radial and axial PMs, the proposed model involves the insertion of mig-magnets, which have a magnetized angle shifted from the reference magnetized angles of axial and radial PMs. This structure leads to the elimination of flux leakage and the concentration of flux linkage in middle of the coil; therefore, the output power is increased by 13.2%.