Nick said:
Hi,
Please let me know why tacho feed back is necessary?? Without Tacho the
Servo motor runs..
Help me..
Feed back is needed to maintain a steady output verses
input reference which is called Tach/Reference feed back otherwise
, its called armature feed back which really does nothing
more than maintain the output voltage to the input voltage
reference ratio. in the case of the second, this is not a
steady reliable way to maintain speed because the motor may
require more voltage on to maintain speed depending on shaft
load&load Swing variations.
Simply put, armature feed back can maintain the output
voltage but not the actual shaft speed on load..
etc...
there are the cases where you have a feed back from some
other reference point inputting to a Trim controller which then
can regulate the input reference to the drive, this would then
be regulated from the Trim control by simply biasing the input
reference of the drive which is in armature mode.
this all applies to DC PM/Shunts and the like motors.