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13
Brushless DC Motor Control
Please note that it is the responsibility of the user to determine the suitability of all parameters, including those
determined by auto-tuning, for use in a given application.
Another method is through trial and error using the Magellan’s built-in trace facility. Finally, it is possible to model
your system and determine the best settings through simulation or analysis; however, a discussion of this approach is
beyond the scope of this manual.
1 3 . 1 0 . 2 R e a d i n g F O C L o o p Va l u e s
To facilitate tuning, there are a number of internal FOC loop values that can be read back as well as traced. To read
back these values the command GetFOCValue is used. To specify these values for trace during automatic trace capture
see the Magellan Motion Processor Programmer’s Command Reference.
Refer to the diagram in Section 13.10.1, FOC Algorithm, for an overview of the FOC loop. The variables within the
FOC loop that can be read or traced are summarized as follows:
Va r i a b l e N a m e
Q Reference, D Reference
Q Feedback, D Feedback
Q Error, D Error
Q Integrator Sum,
D Integrator Sum
Q Integral Contribution,
D Integral Contribution
Q Output, D Output
FOC A Output,
FOC B Output
Phase A Actual Current,
Phase B Actual Current
Function
Are the commanded values input into the Q and D loops. Note that D is always set
to 0 (zero).
Are the measured values for the Q (quadrature) and D (direct) force after re-referencing
from the actual measured current in the phase A, phase B coils.
Are the differences, for the Q loop and the D loop, between the loop reference and
the loop measured value.
Are the integrator sums for the D and Q loops.
Are the contributions of the integral to the overall PI sum for the Q and D loop.
Are the output commands of the Q and the D loops.
Are the phase A and phase B coil commands before output to the motor output
module and PWM generator.
Are the measured currents for the phase A and phase B coils.
13.10.3 FOC with 2-phase Motors
Magellan/ION’s field oriented control algorithm is designed to work with both 3-phase brushless DC motors and 2-phase
microstepping motors. When operating the microstepping motor in this mode (see Chapter 14, Step Motor Control for more
information on Magellan operations with step motors), the basic method is identical. The same three FOC parameters
described in Section 13.13 of this manual, “FOC Algorithm,” are set, and the readable parameters are also the same.
13.10.4 Hall-based FOC
Magellan/ION’s FOC controller can operate with both Hall-based motor position sensing and encoder-based motor
position sensing. The former would only be used in the case that no encoder is available, as use of an encoder
substantially improves smoothness and performance. To set the FOC controller for use with Hall sensors, use the
command SetCommutationMode. The value set can be read back using the command GetCommutationMode.
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Magellan Motion Processor User’s Guide