Dynamic modeling method for an electro-hydraulic proportional valve coupled mechanical-electrical-electromagnetic-fluid subsystems

On the basis of differences of the magnetoresistance, magnetic field direction and relative permeability in metal components, a magnetic cycle method with modifications also characterizing magnetic flux densities of different components in real time is firstly proposed, thus establishing mathematical models for the electromagnetic subsystem of an electro-hydraulic proportional valve. Further integrating electrical, electromagnetic, fluid dynamic and mechanical models together, analytical and fully coupled mathematical models are achieved so that nonlinear dynamic performance determined by the structural parameters, materials, fluid, driving strategies and interaction of subsystems will be captured effectively. Secondly, a coupled finite element (FE) model with all subsystems is also established, and dynamic behaviors under different driving strategies such as the high-low voltage (HL), direct current (DC) and pulse width modulation (PWM) are reflected through the moving mesh method in COMSOL Multiphysics, further suggesting the HL strategy as the better one because of small overshoot and shortest response times. Under the same driving strategy such as PWM, results of two models are highly similar to each other with the maximum time difference of 5 ms and the absolute error of steady-state position of 0.0104 mm. Therefore, two dynamic models are relatively accurate, and such an integrated method presents another reference for predicting dynamic behaviors of complex valves.