Road profile effects on the performance and energy regeneration of the electromagnetic suspension system

This paper deals with the electromagnetic damper, which is composed of a permanent-magnet DC motor, a ball screw and a nut, as the passive, semi-active and active actuator in the vehicle suspension system. The main objective pursued in the paper is to study the dependences of the performance and energy regeneration of the electromagnetic suspension system on the road unevenness and the travel speed. For this purpose, the nonlinear equations of the electromagnetic damper electric circuit in the three mentioned suspension systems are developed. For the vehicle passing over the road unevenness, a seven degrees of freedom model is considered, and the simplest point-follower model is used for the tyre representation. To investigate the electromagnetic suspension system performance and energy regeneration, two types of road unevenness including a road section with a standard pure random profile and a bump modelled by cosine wave of variable height and length are applied. The simulation results demonstrate that an increase in the travel speed leads to the power spectral density increment of the road profile and in turn causes the negative effects on the performance and growth in the energy regeneration. Furthermore, when the bump height gets larger, maximum body acceleration, maximum suspension travel and energy regeneration will increase. There will be a peak on the maximum body acceleration response course when the bump length is equal to 1.1 m because of exciting the sprung mass frequencies. On the maximum suspension travel and energy regeneration response course, there is a peak when the travel speed is equal to 30 km/h, which excites the unsprung mass frequencies.