Control of semi-active suspensions for in-wheel electric vehicles

Abstract

With the electric vehicles highly adoption, there is a need for keeping improving automotive systems. This work is focused on exploring the use of semi-active suspension systems in in-wheel electric vehicles. For that, two different in-wheel concepts are considered. When a brush-less DC (BLDC) motor and when a switched reluctance motor (SRM) are employed. In the SRM, an unbalanced vertical force is taken into account for the vertical dynamics model. The vertical dynamics tests are performed making use of models from one-quarter of vehicle (QoV) andf ull vehicle. Four different semi-active controllers, as well as three current levels, are evaluated and compared in time and frequency domain when employed in the in-wheel and internal combustion engine (ICE) vehicles. The suspension objectives improvement is estimated by making use of some performance indexes. Where the obtained results are compared against the ones given by the 1.25A and F-class baseline suspensions. The results showed that when compared against the F-class baseline suspension, none of the controllers is giving human and ride comfort improvements for the in-wheel electric vehicles. While, in comparison with the 1.25A baseline, the FEB controller is providing the best increase (25%−50%). By the side of the road holding and handling, the M1S guarantees the road holding and handling improvement (10%-25%) for the BLDC. While for the SRM, the FEB controller improves them when compared against the F-class baseline suspension. When taking as reference the 1.25A baseline suspension, the road holding and handling are enhanced by the 1.25A baseline and GH, respectively, for the BLDC. While in the SRM, the FEB controller is giving the best improvement(10%−55%). In most cases, high and low current values guarantee the comfort and road holding improvements, respectively.