TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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edge of the corresponding signal. The signal polarities are programmable and the module reacts only on
toggling the ENABLE register. The signals can be filtered with a configurable digital filter, which suppresses
spike errors.
4.8 FOC23 Engine
Support for the TMC4671 is integrated into the TMCL-IDE including wizards for
set up and configuration. With the TMCL-IDE, configuration and operation can be
done in a few steps and the user gets direct access to all registers of the TMC4671.
Info
The FOC23 engine performs the inner current control loop for the torque current IQ and the flux current
ID including the required transformations. Programmable limiters take care of clipping of interim results.
p
p
Per default, the programmable circular limiter clips U_D and U_Q to U_D_R =
U_D. PI controllers perform the regulation tasks.
(
2)
·
U_Q and U_R_R =
(
2)
·
4.8.1 PI Controllers
PI controllers are used for current control and velocity control. A P controller is used for position control.
The derivative part is not yet supported but might be added in the future. The user can choose between
two PI controller structures: The classic PI controller structure, which is also used in the TMC4670, and
the advanced PI controller structure. The advanced PI controller structure shows better performance in
dynamics and is recommended for high performance applications. User can switch between controllers by
setting register MODE_PID_TYPE. Controller type can not be switched individually for each cascade level.
4.8.2 PI Controller Calculations - Classic Structure
The PI controllers in the classic structure perform the following calculation
Z
t
dXdT = P · e + I ·
e(t) dt
(20)
(21)
0
with
e = X_TARGET − X
where X_TARGET stands for target flux, target torque, target velocity, or target position with error e, which
is the difference between target value and actual values. The time constant d is 1µs with the integral part
t
is divided by 256.
Changing the I-parameter of the classic PI controller during operation causes the
controller output to jump, as the control error is first integrated and then gained
by the I parameter. Be careful during controller tuning or use the advanced PI
controller structure instead. The normalization of the PI parameters might be
changed due to low performance at high PWM frequencies. This will need small
changes in user’s application controller software.
Info
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