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TMC4670 Datasheet PRELIMINARY • IC Version V0.99 | Document Revision V0.91 • 2016-Nov-09
3.7.6 P(I) Position
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.
This is because e = x - x_target might result in larger e[s32] for x[s32] and x_target[s32] represented as s32
for e = x - x_target for x[s16] and x_target[s16] represented as s16.
3.7.7 Inner FOC Control Loop - Flux & Torque
The inner FOC loop (figure 13) regulates the flux current to a flux target of zero and the torque current to
the desired torque target. The inner FOC loop performs the desired transformations according to figure 14
for 3-phase motors (FOC3). For 2-phase motors (FOC2) both Clark (CLARK) transformation and inverse
Clark (iCLARK) a by-passed.
The inner FOC control loop gets a target torque value (I_Q_TARGET) that 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 three target voltage values as input for the PWM engine.
Figure 13: Inner FOC Control Loop
3.7.8 FOC Transformations and PI(D) for control of Flux & Torque
The Clark transformation (CLARKE) maps three motor phase currents (IU
coordinate system with two currents (Iα Iβ). Based on the actual rotor angel 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 ( IQ). The current represents flux and the current IQ represents
torque. The flux just pulls on the rotor but does not effect torque. The torque is effected by the (IQ). Two
,
IV
, IW ) to a two dimensional
,
I
,
I
PI controllers determine two voltages (UD
flux of zero. The determined voltages (UD
,
,
UQ) to drive desired currents for a target torque and a target
UQ) are re-transformed into the stator system by the inverse
Parke transformation (iPARK). The inverse Clarke Transformation (iCLARKE) transform these two currents
into three voltages (UU
,
UV
, UW ). 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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