July 2013 7.9 Field orientation 1109
Field orientation
with absolute
encoder (EnDat)
As soon as the absolute position of the encoder has been read, the absolute
position and determined field angle are assigned to each other.
The field angle is assigned to the zero position of the encoder.
Field orientation via
encoder with Z1
track
After switching on the control, the motor orients itself (rough orientation) via
the Z1 track of the encoder. The drive is ready for operation after this
procedure. The field angle is determined and assigned as soon as the
reference mark is traversed during the first motor motion.
General
information about
encoders for direct
drives
An absolute encoder with EnDat interface should be used, since the
absolute position value is available directly after switch-on, and the field
angle can be assigned immediately. This means that the motor can be
controlled immediately.
The encoder should have a high line count. This leads to better
controllability.
With incremental encoders the motor must first be moved a "minimum"
distance in order to determine a field angle with which the motor can be
moved until the reference mark. Only after the reference mark has been
traversed can the field angle determined during commissioning be
assigned.
If excessive clamping of the axis prevents the "minimum" motion for
determining the field angle, then no field angle can be determined and the
axis cannot be controlled. In this case the clamping must be undone for the
field angle to be determined. If this is not possible, because the axis would
fall down, then an absolute encoder with EnDat interface must be used.
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