USB-2-RTMI datasheet(46/157 Pages) TRINAMIC

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TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11

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4.8.6 PI Velocity Controller

The P part is represented as q8.8 and I is the I part represented as q0.15.

4.8.7 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.

4.8.8 Inner FOC Control Loop - Flux & Torque

The inner FOC loop ( gure 26) controls the

ux current to the

ux target value and the torque current to

the desired torque target. The inner FOC loop performs the desired transformations according to

gure 27

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

rst

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 26: Inner FOC Control Loop

4.8.9 FOC Transformations and PI(D) for control of Flux & Torque

The Clarke transformation (CLARKE) maps three motor phase currents (IU , IV , IW ) to a two-dimensional

coordinate system with two currents (Iα, Iβ). 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 (ID, IQ). The current ID represents ux and the current IQ represents

torque. The

ux just pulls on the rotor but does not aﬀect torque. The torque is aﬀected by IQ. Two PI

controllers determine two voltages (UD, UQ) to drive desired currents for a target torque and a target

ux. The determined voltages (UD, UQ) 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 (UU , UV , UW ). Theses three voltage are the input of the PWM engine to drive the power

stage.

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