关键词: 动态规划, 混合动力, 控制策略, 挖掘机, 转矩预测

Abstract: During the passing decades, even though great progress has been made in hydraulic hybrid excavators with the development of hydraulic hybrid technology, there are still some shortages remained to be solved. For instance, the fuel efficiency is still low and the energy loss is huge. Concerning these issues, a kind of dynamic programming control strategy based on torque prediction, which is suitable for hydraulic hybrid excavators, is proposed. The excavator driving system is a closed hydraulic system comprised by displacement pump and cylinder. The power supply is consisted by engine and displacement pump/motor connected with accumulator, which work as main drive element and auxiliary driving device, respectively. And the driving system can be classified into parallel hydraulic hybrid system. The load characteristics of cyclic operating conditions of excavators are analyzed. The minimum length of sample to forecast demand torque is determined. The demand torque curve is divided periodically based on empirical mode decomposition and the predictive torque is obtained. The dynamic programming control strategy based on torque prediction is proposed. According to the simulation result, the maximum output torque of engine can be reduced by 28.9%, and the fuel consumption can be reduced by 32.5% compared with the condition without control strategy. In addition, the pressure of accumulator can maintain the setting range.

Key words: control strategy, dynamic programming, excavator, hybrid, torque prediction