Simulation analysis on vertical vehicle dynamics of three in-wheel motor drive configurations

The hub-driven technology provides several remarkable benefits to overcome some of today's challenges in electrification of the transport sector. Although there are advantages by using in-wheel motors, their application results in increased unsprung masses, which have a negative impact on ride comfort and road holding of the vehicle. A novel but unexplored concept to inhibit the negative effects of the wheel hub motor is the two-stage-suspension structure. To investigate this in-wheel motor design and to compare it with established concepts for reducing the negative effects of the unsprung masses, three full-vehicle models were established. The vehicle models are based on a two-stage-suspension structure, a design where the motor functions as a tuned mass damper and a conventional in-wheel motor design. The suspension parameters of the three in-wheel motor configurations were further optimized using a genetic algorithm with respect to several vertical vehicle performance parameters. Subsequently, the full-vehicle models of the in-wheel motor configurations were compared by simulation in numerous different driving situations regarding their vertical vehicle dynamics. The results demonstrate that the two-stage-suspension causes an increase of the pitching and vertical vehicle body acceleration in several driving conditions, while the acceleration of the motor in general and the roll acceleration of the vehicle body especially during cornering maneuvers can be reduced significantly.