Based on a critical review of the previous research and the comprehensive theoretical analysis of all functional parts of two-stage electrohydraulic servovalves with a spool position feedback (a current amplifier, a torque motor, the first and the second stage of hydraulic amplification) a detailed mathematical model of the servovalves was created. The analysis was based on the fundamental laws of electromagnetism, fluid mechanics and general mechanics. The model parameters are physical quantities and the complexity of the model is only limited by the possibility of the correct numerical integration. It includes phenomena and quantities that are of influence on the behaviour of the servovalves, so it can predict their function in a wide range of expected working regimes. Results obtained with the numerical modelling on a personal computer were compared with the appropriate experimental data and the validity of the proposed model was confirmed with satisfactory accuracy.

Keywords: electrohydraulics, spool position feedback servovalves, mathematical model