Method for controlling a solenoid valve

A method for controlling a proportional solenoid valve in a hydraulic system, comprising:

• forming a model of the hydraulic system having a predefined control cycle;
• and
• estimating using a programmable controller (i) a pressure prevailing in the hydraulic system at the end of the control cycle and (ii) a coil voltage applied to the coil of the proportional solenoid valve, on the basis of selected variables prevailing at the start of the control cycle, selected physical parameters of components of the hydraulic system, and temperature of a hydraulic fluid,
• wherein the hydraulic system is an ABS/ESP (antilock braking system/electronic stability program) system of a motor vehicle, and wherein physical parameters of the proportional solenoid valve and of a brake caliper are taken into account in the estimating,
• wherein a linear flow rate of the hydraulic fluid is assumed during duration of the control cycle,
• wherein the following equations are used as the basis of the model:
• ⅆ
• I
• ⅆ
• t
• =
• 1
• L
• ⁢
• (
• U
• -
• R
• ·
• I
• )
• ,
• where
• L=inductance of the coil;
• R=ohmic resistance of the coil;
• I=coil current;
• dI/dt=change in coil current over time;
• Q=f1(I, p_mc−p_calip, T_Fluid), where
• Q=flow rate;
• P_mc−p_calip=pressure difference across the proportional solenoid valve;
• I=coil current;
• T_Fluid=temperature of the hydraulic fluid;
• ⅆ
• p_calip
• ⅆ
• t
• =
• E
• ⁡
• (
• p_calip
• ,
• T_Fluid
• )
• ·
• Q
• ,
• where
• p_calip=brake caliper pressure;
• E=hydraulic elasticity of the brake caliper;
• Q=flow rate;
• and
• T_Fluid=temperature of the hydraulic fluid.