Research on the system configuration and energy control strategy for parallel hydraulic hybrid loader

Aimed at the frequent starts/stops operation characteristics of the loader, an energy saving scheme with parallel hydraulic hybrid system is proposed to regenerate and reuse the braking energy normally lost in a conventional loader. Hydraulic hybrid system is designed and sized to capture braking energy from normal–moderate braking operating modes while ensures hybrid system working in higher efficiency region. According to the higher power density characteristic of hydraulic hybrid system, the regenerative braking strategy and energy reuse strategy are designed to coordinate all the powertrain components in an optimal manner while satisfying performance constraints of loader. Energy controller using logic threshold approach is built up to control the dynamic transitions among the various operation modes. Simulation and experimental results show the parallel hydraulic hybrid loader (PHHL) effectively recovered and reused the braking energy, improved the working performance of loader and effectively reduced the fuel consumption.