Design of a 120 W Electromagnetic Shock Absorber for Motorcycle Applications

Abstract

Based on the shock absorber size and power and power density limitations in motorcycle application, a linear permanent magnet machine for a regenerative suspension system that recovers the kinetic energy originating from shock absorber vibration is investigated. To achieve the target power of 120 W, several design parameters were investigated. The eight-slot eight-pole combination was used due to its high power density. A hybrid permanent magnet structure was implemented which was a combination of a classical Halbach array and iron spacers. In addition, the dimensions of the permanent magnet, and stator inner radius were parametrically studied to enhance the air-gap flux density and coil volume, which are the main factors affecting performance. The detailed design generated 124 W of average power under the rated condition, assuming a vibration speed of 0.157 m/s. Despite the satisfaction of the output power and power density, the large magnetic force caused by the interaction between the iron core and permanent magnet is the main drawback of this design, which has a negative impact on driving safety and comfort. To commercialize the suggested device, additional studies will focus on size, electromagnetic reduction, as well as road test performance.