Chapter 1
– General description
8
XtrapulsCD1-pm - User manual
2 - ARCHITECTURE OF A POSITIONER
Electric motor
Electric device that transforms electrical energy into a mechanical movement.
This transformation is often made by means of a current commutation.
Generally, the movement is a rotation but there are also linear motors.
Motor
Electric motor which current commutation is made by mechanical brushes.
Brushless or synchronous
motor
Electric brushless motor. The current commutation is electronically made and
requires a position sensor (resolver, encoder, Hall sensor...).
Resolver
Absolute position sensor over one revolution. The resolver is often used
together with brushless motors because of its robustness.
Encoder
Incremental or absolute position sensor. The encoder is used together with
brushless motors for its accuracy.
Amplifier
Servo drive
Electric device for the control of electric motors. It also includes a current
regulator, a speed servo control and, a position servo control.
Current loop
Current regulator
Used for the motor current control. The motor torque is generally proportional
to the current amplitude.
Speed loop
Speed regulator
Allows the motor speed control with a speed input command.
Position loop
Position regulator
Allows the motor position control.
Positioner
Positioner with position loop and trajectory generator that allows positioning.
Trajectory generator
Generates a speed profile (acceleration, step speed, deceleration) that
allows positioning (start position -> arrival position).
Fieldbus
Digital link that allows real time data exchange between various electric
devices. The characteristic of field busses is their high protection and fault
correction level as well as a predictable communication time.
Profibus
Fieldbus initially defined by Siemens
®
. This bus is widely used in automation.
Enabled/disabled
(Servo On/Off)
When a motor is enabled, it is controlled by the positioner and the servo
loops are operating. When disabled, its rotation is free and there is no current
in the motor.
3 - OTHER DOCUMENTS REQUIRED FOR THE COMMISSIONING
" XtrapulsCD1-pm Profibus positioner Installation Manual".
" XtrapulsCD1-pm Profibus Communication Profile".
Sequence
selection
Trajectory
generator
Position
loop
Speed
loop
Current loop
Current
feedback
Motor
Speed
feedback
Position
feedback
Position
sensor
Logic I/0s
Profibus-DP
interface