An extended state observer based control system of voice coil motor used in direct drive valve

The load disturbances in a voice coil motor-direct drive valve (VCM-DDV) have greater impact on system performance. A mathematical model of the VCM-DDV was established, and a double-closed loop control structure composed of position loop and current loop was presented. A nonlinear PID was applied in position loop. An extended state observer was used to obtain the estimate signals for position feedback signal and its differential, as well as estimate signal for load disturbances. The feedforward compensation for load disturbances was implemented. The simulation and experimental results show the control strategy can effectively overcome the impact on system performance caused by hydrodynamic load. The system position response is fast and no overshoots, and can meet the performance requirements of VCM-DDV. Furthermore, the control algorithm is discrete form, simple calculation structure, and easy to implement in digital controller.