Commutation And Commissioning; Commutation - Beckhoff AL8200 Operating Instructions Manual

9

Commutation and commissioning

9.1

Commutation

Version: 1.0
Commutation and commissioning
The Magnetic Encoder System (MES) serves as feedback for linear
motors of the AL8xxx series. It is to be used exclusively for opera-
tion on a servo drive.
Linear feedback systems are required for the commutation and the
detection of the velocity and position of brushless linear motors.
Such feedback systems consist of a reader head and a scale in-
stalled parallel to the travel path. The AL8200 works directly on the
magnetic plates of the linear motor, eliminating the need for an addi-
tional scale. It detects the magnetic field of the permanent magnets
of the magnetic plates and supplies the encoder signals to the servo
drive. Since the MES is a part-absolute feedback system, no wake &
shake is required in order to determine the commutation angle at
machine start-up. The MES supplies one sine oscillation per logical
motor revolution. A logical motor revolution is equivalent to the dis-
tance between two homopolar magnets, i.e. between two north
poles. The attainable accuracy of ±0.1 mm is sufficient for simple
positioning tasks and depends to a large extent on the mechanical
accuracy and position of the magnets along the travel path. Since
no scale has to be installed, the MES is an inexpensive feedback
solution for linear motors.
Detailed information on the commutation of the AL8000 linear
motor in conjunction with the AL8200 MES can be found in
chapter 9.6.2 of the AX5000 System Manual.
AL8200 ─── 31