Danfoss MCO 305 Design Manual page 24

MCO 305 Design Guide
Synchronizing
Synchronizing is used in applications where 2 or more shafts need to follow each other in velocity or posi-
tion. It can be a simple master-slave system where a slave is following the velocity or position of a master
or it can be a multi-axis system where multiple slaves are following the velocity or position of a common
master signal. Electronic synchronization is very flexible compared to a mechanical shaft, belt or chain as
the gear-ratio and position offset can be adjusted during operation. Velocity and position of the slave drive
is controlled based on a master encoder signal, a feedback encoder signal as well as the set gear-ratio.
During synchronization the slave is always restricted by maximum velocity and acceleration/ deceleration
(parameter group 33-8*). In addition the allowed deviation between master and slave velocity can be
restricted by parameter 33-14, e.g. 33-14 = 5% means that the slave can only be 5% faster or slower than
actual master velocity when doing position corrections.
MCO 305 offers 3 basic types of synchronization:
For synchronous operation of two or more drives you can use
Velocity synchronization
Position synchronization
Marker synchronization
Velocity Synchronization (SYNCV)
Velocity synchronization (SYNCV) is closed loop velocity control where the set-point is the master velocity
multiplied by the gear-ratio and the actual velocity is measured by the slave encoder; position deviations
will not be corrected. Note however that using the Integral part of the PID controller will lead to some level
of position correction as the integral sum of velocity is equal to position.
The slave must be at least as fast and dynamic as
the master in order to maintain accurate synchroni-
zation, i.e. the slave must be able to match the
maximum velocity, acceleration and deceleration of
the master. Already during the design phase it is
thus important to consider making the least dyna-
mic shaft the master as this shaft will anyway be
the limiting factor for the system performance.
Typical applications are:
Synchronizing of two or more conveyors
Material stretching
Mixing
Application Example: Suit Case Conveyor Belt
Two or more conveyor belts must run at the same
speed in order to get a smooth transfer of the suit
case from one conveyor belt to the next.
In addition to start and stop of velocity synchroni-
zing the sample program has a manual mode with
the possibility to increase and decrease the velocity
via digital inputs.
NOTE: The following is just an example and the presented settings and programs might not cover the
complete functionality required by a real application.
It is assumed that the motor and encoder connections are checked and that all basic parameter settings
such as motor data, encoder data and PID controller are done. Instructions for setting up parameters can
be found in FC 300 Operating Instructions and MCO 305 Operating Instructions.
24
__ Functions and Examples __
Control behavior with velocity synchronization.
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