Effective regenerative braking control for smooth stop of a hybrid electric bus

Regenerative braking is an important function for a hybrid electric bus with many stop-to-go drive conditions. Yet an accurate nonlinear model for the composite brake system in HEV and a nonlinear model-based control design for a series-parallel hybrid electric bus have not been fully studied. This paper describes the brake system with regenerative braking function, and a special brake pedal is applied in this brake system. A hybrid electric bus is inherently a nonlinear system with many uncertainties. Parameter estimation design is used to improve the effect introduced by the parametric uncertainties. The backstepping-based controller design technique is introduced with the estimated parameters, and the error dynamics is separated from the parameter adaptation. Experimental data are used for the demonstration simulation. The simulated output shows a good tracking performance of the practical braking vehicle speed, and the bus can stop at a bus station by regenerative braking. The effectiveness of the proposed controller design is illustrated with the adaptive system parameters.