In some applications, both speed control and torque control of the follower are
required. In those cases, the operating mode can be switched by parameter (19.12
or 19.14). Another method is to set one external control location to speed control
mode, the other to torque control mode. Then, a digital input of the follower can
be used to switch between the control locations. See chapter Control locations
and operating modes (page 23).
With torque control, follower parameter 26.15 can be used to scale the incoming
torque reference for optimal load sharing between the master and the follower.
Some torque-controlled follower applications, eg. where the torque is very low, or
very low speed operation is required, may require encoder feedback.
If a drive needs to quickly switch between master and follower statuses, one user
parameter set (see page 120) can be saved with the master settings, another with
the follower settings. The suitable settings can then be activated using for example,
digital inputs.
Load share function with a speed-controlled follower
Load sharing between the master and a speed-controlled follower can be used in
various applications. The load share function is implemented by fine-tuning the
follower speed reference with an additional trim signal based on a torque reference.
The torque reference is selected by parameter 23.42 (by default, reference 2 received
from the master). Load share is adjusted by parameter 26.15 and activated by the
source selected by 23.40. Parameter 23.41 provides a gain adjustment for the speed
correction. The final correction signal added to the speed reference is shown by
23.39. See the block diagram on page 651.
Note:
• The function can be enabled only when the drive is a speed-controlled follower
in remote control mode.
• Drooping (25.8) is ignored when the load share function is active.
• The master and follower should have the same speed control tuning values.
• The speed correction term is limited by the speed error window parameters
24.44 and 24.43. An active limitation is indicated by 6.19.
• For a reliable ramp stop of a follower,
• both parameters 24.43 and 24.44 must be set smaller than parameter 21.6
(or speed error window control disabled altogether by 24.41), and
• parameter 24.11 must be set smaller than parameter 21.6.
Communication
A master/follower link can be built by connecting the drives together with fiber
optic cables (may require additional equipment depending on existing drive
hardware), or by wiring together the XD2D connectors of the drives. The medium
is selected by parameter 60.1.
68 Program features
To Next Page
Loading...
