User Manual

Table Of Contents
Field Oriented Control (FOC) mode Operation
Advanced Digital Motor Controller User Manual 135
Speed Limiting in FOC Torque Mode
AC Induction Controllers provide a way of smoothly limiting the speed in FOC torque
mode to prevent motor runaways. The method for limiting the speed is based on PID
speed over-ride control which provides very smooth motor output but requires PID tuning.
The speed loop PID tuning can either be done in “FOC torque mode” at the speed limit or
in “FOC Speed Mode” by looking at the response time.
When in “FOC Torque Mode, command some torque to the motor and cause the
motor to spin to the speed limit. Some low frequency ripple will be noticed in the
speed which should be minimized by increasing PID gains. Increase the PID gains
to a point where no ripple is seen.
If in “FOC Speed Mode, tune the speed PID gains by looking at the response time
of the motor. And then move to case 1) to check the ripple in the speed.