Service Training
Section 2.6
Page 56
2.6.6.10 CURRENT SENSOR
The current sensor senses the armature current of both traction motors and sends a signal to the electronic
traction control unit. The current sensor contains a Hall generator and an adaptive circuitry. Hall generators
consist of very thin semiconductor plates to which a constant control voltage is applied on the ends. This
control voltage causes a constant current to flow.
When a magnetic field caused by the flux of the motor current penetrates the semiconductor area, a voltage
(Hall voltage) can be measured at the side of the semiconductor plate. This Hall voltage increases with the
force of the magnetic field or of the motor current.
As the Hall voltage ranges only within a range of a few 100 mV, it is amplified by the integrated adaptive circuit
and fed back to the electronic traction control unit.
The adaptive circuit is integrated in the current sensor and it supplies the following output voltages (output
signal measured at connector 1X6 between terminals 2 and 3):
Motor Current Output Signal
0 A 7.5 V
100 A 8.0 V
200 A 8.5 V
300 A 9.0 V
400 A 9.5 V
430 A 9.65 V
This means that for each 100 A increase in current, the output voltage changes by 0.5 V.
Hall voltage
magnetic field
from the motor current
constant
current
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