Variable Structure Control Strategy Research on Regenerative Braking for a Brushless DC Motor Driven Electric Bus Cruising Downhill

摘要

To use regenerative braking to act as an auxiliary brake to maintain the constant speed of a brushless DC motor driven electric bus (BDCMEB) on downhill based on the feature of double-loop control structure of the control method for electric vehicle traction motor and the variable structural characteristics of PWM Control System for brushless DC Motor. A double-manifold variable structure control method to control regenerative braking is proposed for the bus cruising downhill. The impact of lead-acid battery's charge acceptance ability over a long charging period on the regenerative braking force of a driving motor is analyzed. Dynamic model of the bus on long downhill is established. A double-manifold variable structure controller is designed for the DCMEB on long downhill. The simulation result shows that the control system maintains enough stability and strong robustness. It may be achieved for the bus to maintain a constant speed downhill only by regenerative braking on a smaller slope. But the dynamic process is very slow. When deceleration or a constant speed is desired on a larger slope, only by electro mechanical parallel braking can the bus track the target speed precisely and quickly.