6-14 TUNING THE CONTROL LOOPS
SB1391 Hardware and Setup Guide - Document revision no. 1.14
6. Generally, the Current (% of max) can be left at 10%. When the amplifier is relatively
oversized for the motor, the Current (% of max) can be set lower than 10%.
Alternately, if the amplifier is undersized, the Current (% of max) can be set higher
than 10%. But the value should not be set higher than 50%.
7. Click OK to complete the Current loop adjustment step.
6.4. Commutation
The Commutation adjustment step identifies the correct phasing of the motor in relation to the
position feedback reading. It also provides comprehensive testing and verification to ensure
accurate phasing.
Commutation is required only for a DC brushless (AC servo/AC synchronous) motor or AC
induction motor.
• For a DC brushless (AC servo/AC synchronous) motor, the purpose of the commutation
adjustment is to align the permanent magnet orientation with the reading of the feedback
device (encoder, encoder + Hall, resolver).
• For an AC induction motor, the purpose of the commutation adjustment is to align the
motor windings orientation with the reading of the feedback device and to properly set the
polarity of the Field Current (FC) and Slip Constant (SK) parameters.
It is recommended, if possible, to perform this step without any load attached to the motor.
Action
1. Click the Preferences button to open the Commutation preferences dialog box.
2. Select the appropriate tests and settings.
3. Click the OK button to close the Commutation preferences dialog box.
4. Click the Go button to start the commutation adjustment.
5. Click OK upon successful completion.
6. Click OK to complete the Commutation adjustment step.
6.4.1. Problems with Commutation
The encoder resolution is incorrect (1000 instead of 1024), therefore the settings of LR and
LF are wrong.
♦ 1. Read the index location in order to clear the index buffer (RXIX<cr>).
♦ 2. Manually rotate the motor a little more than one full turn.
♦ 3. Read the index location (RXIX<cr>).
♦ 4. Manually rotate the motor a little bit more than one full turn.
♦ 5. Read the index location (RXIX<cr>). The difference between the last two
readings is the exact number of counts/rev.
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