Patent ID: 6591204
Filing Date: 2003-07-08
Classification: F01L

Abstract:
A method of estimating magnetic flux (&phgr;) in an electromagnetic actuator for controlling an engine valve, the electromagnetic actuator including an actuating body being made at least partly of ferromagnetic material, and being moved towards at least one electromagnet by magnetic attraction generated by the electromagnet, the method comprising:measuring various electric quantities (i, v; va) of an electric circuit connected to a magnetic circuit, wherein the voltage (va) at terminals of an auxiliary coil connected to the magnetic circuit and linking the magnetic flux (&phgr;) is measured, the auxiliary coil being substantially electrically open; calculating the time derivative of the magnetic flux (&phgr;) as a linear combination of the electric quantities.(i, v; va); and integrating in time the derivative of the magnetic flux (&phgr;), wherein the time derivative of the magnetic flux (&phgr;) and the magnetic flux (&phgr;) itself is calculated according to the following equations: &dd;&varphi;&af;(t)&dd;t=1Na&CenterDot;vaus&af;(t)&varphi;&af;(T)=1Na&CenterDot;&Integral;0T&it;vaus&af;(t)&it;&dd;t+&varphi;&af;(0)where:&phgr; is the magnetic flux (&phgr;) Na is the number of turns of the auxiliary coil va. is the voltage (va) applied to the terminals of the auxiliary coil.