Patent ID: 11961665
Assignee: BEHR-HELLA THERMOCONTROL GMBH
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  B  G | IPC B  G  H

Claim 1:
2. A method for controlling an armature solenoid for generating a predefined force to be exerted by the armature solenoid for use in a vehicle operating unit with haptic feedback, which solenoid has a potentially changed air gap width in an idle state, the method comprising the following steps:
providing a look-up table or a mathematical modelling of the electromagnetic behavior of the armature solenoid, wherein a result from the look-up table or the mathematical modelling which PWM signal defined with respect to pulse width and/or duration is to be applied to an exciter coil of the armature solenoid for different assumed air gap widths in order to generate a predefinable force to be applied by the armature solenoid, and
determining the air gap width of the armature solenoid by
operating the armature solenoid as a resonant circuit with a buffer capacitance connected in parallel to the exciter coil,
determining the resonant circuit frequency from the voltage drop over the exciter coil, with the buffer capacitance being known,
determining the inductance of the exciter coil based on the resonant circuit frequency and the known buffer capacitance, and
determining the current air gap width based on the number of windings of the exciter coil and the cross sectional area of the air gap of the armature solenoid, and

controlling the exciter coil by the PWM signal which is obtained based on the look-up table or the mathematical modelling, with the force to be exerted and the determined air gap width being given.