[techhelpbb]

To make what I wrote above a bit easier to read...

Current shunt....is a resistor often of a small value.

The resistor is put in series with the load (in this case the circuit controlling the motor), and because of it's small value it develops a small but proportional voltage across it. That voltage is proportional to the current in the circuit because of Ohm's law.

A 'current shunt monitor' or 'current sense amplifier' or 'current sense monitor' is an analog circuit designed to monitor the small voltage that develops across a current shunt resistor and usually to amplify it to some extent. For example the INA193 will multiply that voltage by a fixed 20x.

So if the 0.001 Ohm resistor in the Jaguar had a voltage of 0.1 Volts across it (the maximum) the INA193 that measure it would have a voltage of 2 Volts across it. That's okay the microcontroller operates on 3.3 Volts.

Also for those that don't know...when a motor field collapses the current that flows will be reversed from the direction of flow of the current that charged that field. So basically, as the Jaguars are built now they can only measure the current they put into the motor's fields. Not the current that flows back from the fields collapsing. If they put the 'bidirectional' current shunt monitor into that circuit they could measure that reverse current if they were able to do so fast enough...I suspect this was considered to be not essential.