Dynamic of hydrogear drive systems
Research Task/Objectives
Drive concept of HydroGear systems
With a demand for energy efficient process control, electrohydraulic drive systems with either variable displacement or variable speed of the pump have been established in industrial applications. Socalled HydroGear systems combine both concepts, and offer a degree of freedom for process control in the form of speed and displacement variable pump drives.
Intelligent algorithms have to be developed to maximize the benefit of the availability of two actuators in hydraulic applications. Besides energy efficiency, process dynamics in particular play a crucial role. Shorter cycle times directly increase the production volume and therefore contribute to the profitability of a work machine.
Approach/Results
Results of the model based optimization of process dy-namics
To reach the maximum process dynamics, the mutual influences of motor and pump dynamics have to be modeled in a first step. By considering a simplified loss model, the optimal sequences for drive speed and pump dis-placement can be determined through a subsequent transformation into a mathematical optimization problem. In doing so, the rising time for a volume flow set point jump was exemplary reduced while lowering the maximum necessary pump speed at the same time.