User`s manual

CHAPTER 5.0 Functional Overview 5-21
CDS7324 (FORMERLY LSF-0819)
Rev. A INSTALLATION & USER’S MANUAL
5.7 Commutation Module
The commutation module allows the selection of various commutation methods for the motor phase currents. It
is possible to use a resolver, an encoder, or a fixed value for the rotor feedback position.
5.7.1 Commutation Configuration
5.7.1.1 Commutation feedback
The selection of the rotor position feedback is done through parameter commutation_feedback
(Field Number
1035). It can have the following values:
0 - commutation with angle zero
1 - commutation with resolver feedback
2 - commutation with encoder feedback
5.7.1.2 Commutation with zero angle
When selecting commutation_feedback
=0 the feedback angle for the rotor position is fixed at zero. This can be
used to determine the phase angle between the rotor and the resolver or encoder. When this mode is selected,
the current loop gains may have to be reduced to avoid instabilities.
5.7.1.3 Commutation with resolver
When commutation with resolver is selected, the rotor angle is taken from the resolver commutation position
resolver_position. 16-bit full scale corresponds to one full mechanical revolution. The number of resolver poles
resolver_poles
and the number of motor poles motor_poles has to be set to insure proper operation of the drive.
5.7.1.4 Commutation with encoder
If the motor is equipped with an encoder, the commutation is done from the encoder commutation angle
encoder_commutation_position
. 16-bit full scale corresponds to one full mechanical revolution. The encoder
type and line count have to be set up before. See 'Encoder Module' for further information.
5.7.1.5 Commutation offset
In all commutation types the parameter commutation_offset
(Field Number 1036) contains the offset angle
between the commutation feedback and the phase currents. 16-bit full scale corresponds to one full mechanical
revolution. When the motor has a resolver or encoder built in that has been adjusted in the factory this angle can
be obtained from the motor data. Otherwise it is possible to do an automatic adjustment of this value using the
commutation adjustment parameter commutation_offset_adjustment
.