Control of a hydraulic regenerative braking system for a heavy goods vehicle

This paper investigates the fuel consumption of an articulated vehicle with a hydraulic regenerative braking system. The vehicle is a four-axle tractor–semitrailer with a volume-limited payload. It is equipped with hub-mounted hydraulic pump–motor units that pump fluid from a low-pressure reservoir to a high-pressure reservoir during braking events and generate a propulsive torque when high-pressure fluid flows through them to the low-pressure reservoir during acceleration. Several possible control strategies are proposed and simulated using a validated mathematical model of the fuel consumption of the vehicle. A global optimisation calculation indicates that the maximum possible reduction in fuel consumption due to the regenerative braking system is 11–22%, depending on the driving cycle. The simulations indicate that the simple ‘greedy’ algorithm decreases the fuel consumption by 9–17% for the same conditions. Two heuristic algorithms and a model predictive control approach were also investigated. Although these more sophisticated controllers were able to improve on the greedy controller slightly for some conditions, they may not be implementable in practice.