User Manual

Table Of Contents
Operating Brushless Motors
Advanced Digital Motor Controller User Manual 129
After the setup is complete, the motor will stop, BECC and SVT values will be printed on
the console and saved in the controller’s configurations flash memory.
In case BECC is reported as a negative number, the calibration will be treated as a failure,
and the error message “BEMF Integration Limit Detection FAILED!” will be displayed in
the console
If the calibration was successful, message “BEMF integration limit detection OK” will
be printed in the console and the values of BECC and SVT will be displayed too, then the
motor is ready to use. Send motor commands in open loop and verify that it runs in both
direction with reliability startup.
Further verification is possible by using an oscilloscope connected to any of the motor
phases. Verify that the signal is symmetrical as shown in figure 8-5. If it is imbalanced,
this means that the Back EMF Integrator Limit (SVT) needs further adjustment. You can
change the value manually until the left and right ramps look symmetrical.
Important Warning
Beware that the motor will spin at maximum speed during calibration/auto-tuning.
Make sure it is safe to do so before initiating. Be ready to cut to power instantly at
any time during the tuning process.
Closed Loop Modes in Sensorless
Closed loop speed mode can be used with sensorless motors. The speed is determined
by measuring the time between commutations. Sensorless motors will work the same as
sensored motors and require similar PID tuning. The only limitation is at very slow speed
where the motor cannot be made to go slower than the RPM resulting from the Startup
Frequency parameter.
Position modes, and the Speed Position modes cannot be used reliably with sensorless
motors.
Operating Brushless Motors
This section covers operating features that are common to Brushless Motor control, re-
gardless of the commutation mode.
Once configured and tuned, a brushless motor can be operated exactly like a DC motor
and all other sections in this manual are applicable. In addition, the Hall sensors or encod-
ers, provide extra information about the motor’s state compared to DC motors. This infor-
mation enables the additional features discussed below.
Stall Detection
The rotor sensors and the encoders can be used to detect whether the motor is spinning
or not. The controller includes a safety feature that will stop the motor power if no rotation
is detected while a given amount of power is applied for a certain time. Three combina-
tions of power and time are available: