Droop Block "Current Scale" (Speed Droop) - GE AV-300i User Manual

1.8.8 Droop Block "Current scale" (Speed Droop)

The Function of the Droop Block is active only in a Sensorless and Field oriented mode.The Block is made of:
- a comparison node between the torque reference (generated by the speed regulator or with trq 2?) and the
Droop Comp variable
- a proportional regulator whose output is (added or subtracted) to the overall speed reference. This is supplied
with a low passing filter and a limit on the correction to be provided
It is used, for example, with the coupling of two motors. The advantage of using the Droop Block is the possibility
to let the speed regulators enabled on both Drives. The correction on the Drive reference, when the Droop Block
is enabled, avoids the loop saturation. In case a load loss occurs on one of the two motors, the speed is controlled
with a difference as compared to the reference of Droop limit al +.
This function is used to realize a current scale. It is typically used when two motors are mechanically combined
one with the other (ex. they are connected on the same shaft). They both must rotate at the same speed. If one
of the two motors tends to rotate at a higher speed, the consequence is a difference typical for the control Drives
and an overload condition. The second motor acts as a brake.
Such a condition causes an unbalance between the two currents, which can be eliminated via the Droop Func-
tion. By adding a correction term to the Drive speed reference (proportional to the load difference), the two
currents on the motors are balanced again.
The Droop enable src source states the origin of the signal enabling the Droop function.
Droop comp src allows the connection of the Droop reference signal (standard connected to the Droop comp
internal reference).
In the Block configurations it is possible to set: with Droop gain the function gain, with Droop filter the time
constant of the input filter, with Droop limit the allowed reference correction limit and with Droop comp the
value of the internal reference.
It is possible to monitor the Block output, Droop out (in rpm).
The Block inputs are:
The outputs:
Description:
SPEED CONFIG
SPEED CONFIG SAVE PARAMETERS
Ch.1
106
GEH-6641E
· Droop enable src
· Droop comp src
· Droop output
Speed droop
Speed droop src
Droop en src
Droop comp src
Speed droop cfg
Droop gain
Droop filter
Droop limit
Droop comp
Speed droop mon
Droop out
—————— Function Description ——————