Datasheet
TMC4671 Datasheet • IC Version V1.3 | Document Revision V2.00 • 2020-Apr-17
55 / 142
4.7.8 P Position Controller
For the position regulator, the P part is represented as q4.12 to be compatible with the high resolution
positions - one single rotation is handled as an s16. For the advanced controller structure the P part is
represented by q8.8.
4.7.9 Inner FOC Control Loop - Flux & Torque
The inner FOC loop (figure 32) controls the flux current to the flux target value and the torque current to
the desired torque target. The inner FOC loop performs the desired transformations according to figure 33
for 3-phase motors (FOC3). For 2-phase motors (FOC2) both Clarke (CLARKE) transformation and inverse
Clarke (iCLARKE) are bypassed. For control of DC motors, transformations are bypassed and only the first
full bridge (connected to X1 and X2) is used.
The inner FOC control loop gets a target torque value (I_Q_TARGET) which represents acceleration, the rotor
position, and the measured currents as input data. Together with the programmed P and I parameters,
the inner FOC loop calculates the target voltage values as input for the PWM engine.
Figure 32: Inner FOC Control Loop
4.7.10 FOC Transformations and PI(D) for control of Flux & Torque
The Clarke transformation (CLARKE) maps three motor phase currents (
I
U
,
I
V
,
I
W
) to a two-dimensional
coordinate system with two currents (
I
α
,
I
β
). Based on the actual rotor angle determined by an encoder
or via sensorless techniques, the Park transformation (PARK) maps these two currents to a quasi-static
coordinate system with two currents (
I
D
,
I
Q
). The current
I
D
represents flux and the current
I
Q
represents
torque. The flux just pulls on the rotor but does not affect torque. The torque is affected by
I
Q
. Two PI
controllers determine two voltages (
U
D
,
U
Q
) to drive desired currents for a target torque and a target
flux. The determined voltages (
U
D
,
U
Q
) are re-transformed into the stator system by the inverse Park
transformation (iPARK). The inverse Clarke Transformation (iCLARKE) transforms these two currents into
three voltages (
U
U
,
U
V
,
U
W
). Theses three voltage are the input of the PWM engine to drive the power
stage.
In case of the FOC2, Clarke transformation CLARKE and inverse Clarke Transformation iCLARKE are skipped.
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