Hierarchical control of energy regulation based variable-speed electrohydraulic drive

The variable-speed electrohydraulic drive, which can achieve similar energy efficiency as volume drive system, has some excellent features. But the main disadvantages, which are slow response and poor low-speed performance, limit its development. The energy regulation based variable-speed electrohydraulic drive is a good solution to solve these problems by adding an energy regulation device and a main-circuit throttling valve into the system. However, it is a multiple-input multiple-output control system, coupled with strong nonlinear and some parameters of volatility and uncertainty, which make the control strategy complicated. The hierarchical control strategy is proposed, which is composed of three layers, the energy layer, control layer and feedback layer. The principles and implementations of the three layers are discussed in detail. The simulation and experiment results have showed its performance.