SMT-BD2
5.2
–
COGGING COMPENSATION SETUP FOR ROTATING MOTORS
!
Cogging torque compensation is only valid on brushless rotating motors equipped with an
encoder providing one marker pulse per motor revolution.
Start the amplifier commissioning and adjustment as described in
.
Uncouple the motor from the load in order to avoid any external disturbance on the shaft during the cogging
torque acquisition procedure.
Select the
PI
2
controller and the
High Bandwidth
, then execute the
Auto-tuning
procedure.
Execute the
Cogging torque acquisition
procedure. This procedure is taking a few minutes because the motor
is moving at low speed over 1 or 2 revolutions in both directions. The acquired cogging torque value is
automatically stored in the amplifier CT/BD2 memory during the procedure execution.
!
The motor shaft must not be disturbed during the cogging torque acquisition procedure.
For checking the cogging torque compensation effects on the motor shaft, proceed as described below :
Switch the amplifier in torque control mode by activating the CI input (X4 connector, pin 4) and short-circuit or
open the analog command input CV (X4 connector, pins 15, 16 and 17).
Execute the
Offset compensation
procedure.
Check manually for the reduction of the cogging torque effects, by moving the motor shaft when the
Cogging
compensation
command is activated and the amplifier enabled. If some resistant points do remain over one
complete motor shaft revolution, renew the acquisition procedure.
Switch off the amplifier and couple the motor to the load.
Switch on the amplifier again, enable the
Cogging compensation
command and execute the
Save parameters
to EEPROM
procedure.
!
At the amplifier power up the cogging torque compensation is only effective after the detection of the
first encoder marker pulse.
When changing either the motor, the encoder or the amplifier, the cogging torque acquisition
procedure must be renewed.
5.3
–
COGGING COMPENSATION SETUP FOR LINEAR MOTORS
!
Cogging force compensation is only valid on brushless linear motors equipped with an encoder
providing only one marker pulse over the entire motor travel. The motor must also be equipped with
positive and negative travel limit switches connected on the X4 connector (FC+ and FC- inputs). The
maximum motor travel distance (from the negative to the positive limit switch) is limited at 4000000
encoder counting increments. The CT/BD2 memory can store up to 8000 cogging compensation points;
so the cogging compensation pitch is equal to the motor travel distance value divided by 8000.
Start the amplifier commissioning and adjustment as described in
. Check that the motor positive and
negative travel limit switches are operating correctly.
!
In the case of a motor with an unbalanced load (constant force due to the gravity effect on a non
horizontal axis), the cogging compensation will include the gravity force. In this case the cogging
compensation is only valid if the motor current value corresponding to the gravity force effect is lower
than 5% of the amplifier current rating.
53
Chapter 8 - Appendix
