A parsimonious model for the proportional control valve

A generic non-linear dynamic model of a direct-acting electrohydraulic proportional solenoid valve is presented. The valve consists of two subsystems-a spool assembly and one or two unidirectional proportional solenoids. These two subsystems are modelled separately. The solenoid is modelled as a non-linear resistor-inductor combination, with inductance parameters that change with current. An innovative modelling method has been used to represent these components. The spool assembly is modelled as a mass-spring-damper system. The inertia and the damping effects of the solenoid armature are incorporated in the spool model. The model accurately and reliably predicts both the dynamic and steady state responses of the valve to voltage inputs. Simulated results are presented, which agree well with experimental results.