Audi 243 Service Manual page 26

System components
Function
The exciter coil is subjected to an alternating
current which produces an electromagnetic
alternating field, the induction of which is
penetrated by the rotor.
The current induced in the rotor produces a
second electromagnetic alternating field
around the conductor loop (rotor).
Both alternating fields, from the exciter coil
and from the rotor, act on the receiver coils
and induce corresponding alternating
currents in them.
While the induction of the rotor is
independent of its angle position, induction
of the receiver coils depends on their
distance from the rotor and thereby on its
angle position.
As the rotor, depending on its angle position,
overlaps differently with regard to each
receiver coil, their voltage amplitudes vary in
accordance with the angle position of the
rotor.
The evaluation electronics compensate the
alternating currents of the receiver coils,
amplify them and produce proportional
output voltages for the three receiver coils
(proportional measurement). After voltage
evaluation, the result is converted into output
signals for the level sensors and transmitted
to the control units for further processing.
26
Exciter coil
Stator
1st magnetic
field at the
exciter coil
Rotor
2nd magnetic
field in the
conductor loop
Voltage amplitudes depending on the position of
the rotor with regard to the receiver coil
(example of a rotor position)
U
1
0
U
2
0
U
3
0
3 receiver coils
U
3
U
2
U
1
243_036
Conductor loop
(induced current)
Time
Time
Time
243_037