Performance of Differential Cylinder Position Servo System Controlled by Permanent Magnet Synchronous Motor Driven Pump

To control differential cylinders with an AC servo motor driven constant pump is a new method and recently becomes the research focus for energy saving in electro-hydraulic control systems.Since the pilot check valve for flow distribution was incompetent,three flow distribution windows were used to compensate the different volumetric flow caused by differential cylinder area ratio.This method can reduce the flow exchange of the pilot check valve,and improve the system's energy efficiency.Due to the existed problems,such as serious non-linearity,bump leakage and other uncertain factors in the system,higher noise and stronger vibration were generated when the cylinder was retracted.To overcome these disadvantages,a compound control algorithm that combined velocity and acceleration feed-forward compensation with anti-saturation integral separation PID controller was adopted.The controller's parameters were determined by simulation.The experimental results demonstrate that the proposed method has effectively improved the system's dynamic properties and robust stability,reduced noise and vibration,and thus achieve the symmetry of moving speed in both directions.