Datasheet

TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.03 • 2018-Sept-06
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Info
The PI velocity controller will be given a derivative part (so it will be a PID controller)
in a future version of the chip. Also, the normalization of the PI parameters might
be changed due to low performance at high PWM frequencies. This will need
changes in the user’s application controller software.
Info
The P Factor in the advanced position controller is not properly scaled. Due
to the high gain in velocity control loop, the position controller gain should be
respectively low. The P Factor normalization of Q8.8 does not match these needs.
This will be changed in a future version of the chip to a different Q format.
This change will need changes in the user’s application controller software. We
recommend to use the classical PI control structure if performance is not sufficient.
4.8.4 PI Controller - Clipping
The limiting of target values for PI controllers and output values of PI controllers is programmable. Per
power on default these limits are set to maximum values. During initialization, these limits should be set
properly for correct operation and clipping.
The target input is clipped to X_TARGET_LIMIT. The output of a PI controller is named dXdT because it gives
the desired derivative d/dt as a target value to the following stage: The position (x) controller gives velocity
(dx/dt). The output of the PI Controller is clipped to dXdT_LIMIT. The error integral of (20) is clipped to
dXdT_LIMIT / I in the classic controller structure, and the integrator output is clipped to dXdT_LIMIT in the
advanced controller structure.
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