Datasheet

TMC4671 Datasheet • IC Version V1.3 | Document Revision V2.00 • 2020-Apr-17

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Figure 30: Advanced PI Controller

Info

The P Factor normalization as Q8.8 of the advanced PI controller of the TMC4671-

ES is selectable for the TMC4671-LA as either Q8.8 or Q4.12. Using Q4.12 needs

changes in the user’s application controller software when using the Advanced PI

position controller.

The transfer function of the advanced PI controller can be described by the following pseudo code:

dXdT = e · P · (1 + integrator + I) (31)

integrator = integrator + P · I · e (32)

P and I are either displayed as Q8.8 (P = P_FAK/256) or Q4.12 (P = P_FAK/4096). This is individually

conﬁgurable for each controller parameter in the controller cascade.

4.7.5 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 (27) is clipped to

dXdT_LIMIT / I in the classic controller structure, and the integrator output is clipped to dXdT_output_limit

in the advanced controller structure.

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