I have two separate questions here, I think.
1. If I use LEM current sensors instead of shunt resistor measurement in an FOC design, where should the LEM sensors be in the circuit, in-line with the load, or somewhere else? Also, how many LEM sensors are needed, or preferred? From reading the Instaspin User Guide, I know that a three shunt solution is the best for shunt resistor measurement
2. Am I correct in thinking that phase and dc bus voltage measurements are only used when the FAST algorithm is being used, and that is only used for a sensorless motor drive? If I have a motor with absolute encoder position sensing and am deriving motor pole-position from this, can I dispense with the voltage measurements or are they used for some other purpose?
I had a system working from the 69M-KIT some time ago but am now using the Launchpad-XL 28069M board with the BOOST-XL, and a custom plug-in board with LEM current sensors, which can be wired into the circuit where appropriate.
Thanks for any help with this.
Regards,
Geoff