Development of a Direct-Drive Servo Valve With High-Frequency Voice Coil Motor and Advanced Digital Controller

摘要

There is increasing demand for the hydraulic direct-drive valve (DDV) due to its higher reliability than conventional two-stage servo valves. The objective of this paper is to propose a new DDV with high-frequency voice coil motor (VCM) and advanced digital controller. A permanent magnet Halbach array is employed in the design of VCM to generate high flux density in the air gap, and thus increase force output. Both finite-element analysis and experiments are conducted to validate the performance improvements of VCM. A digital controller based on DSP and field-programmable gate array is developed to control the valve motion. A hybrid controller based on disturbance observer and sliding model control (SMC) scheme with a state-space observer is proposed for the DDV system. The static testing indicates that the discrete-time SMC with unmodeled load compensator improves the control accuracy and robustness of the system. The dynamic response testing indicates that the frequency bandwidth of the system is up to $hbox{450 Hz}$ for $hbox{25%}$ of full stroke. It is higher than existing commercial VCM-DDVs.