Watson-Marlow MM440 - Manual (Page 241)

Issue 10/06 3 Functions
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0 241
3.23.1.4 V/f open-loop control with flux current control (FCC)
Parameter range: P1300, P1333
Warnings -
Faults -
Function chart number:
-
An improved current measurement function has been
developed for our MICROMASTER drive inverters. This
permits the output current to be precisely determined referred
to the motor voltage. This measurement guarantees that the
output current is sub-divided into a load component and a flux
component. Using this sub-division, the motor flux can be
controlled and can be appropriately adapted and optimized
in-line with the prevailing conditions.
FCC operation is only activated after the FCC starting
frequency P1333 has been exceeded. The FCC starting frequency P1333 is
entered as a percentage to the rated motor frequency P0310. For a rated motor
frequency of 50 Hz and a factory setting of P1333 = 10 %, this results in an FCC
starting frequency of 5 Hz. The FCC starting frequency may not be selected too
low as this has a negative impact on the control characteristics and can result in
oscillation and system instability.
The "V/f with FCC" control type (P1300 = 1) has proven itself in many applications.
It has the following advantages with respect to the standard V/f control:
¾
Higher motor efficiency
¾ Improved stabilizing characteristics
♦ → higher dynamic response
♦ → improved behavior to disturbances / control
NOTE
Contrary to closed-loop vector control with / without speed encoder (VC / SLVC),
for the V/f open-loop control mode with FCC, it is not possible to specifically
influence the motor torque. This is the reason that it isn’t always possible to avoid
the motor stalling – even when using "V/f with FCC".
An improvement in the stabilizing behavior and in the motor efficiency can be
expected when using the closed-loop vector control with / without speed encoder
when compared to V/f control with FCC.
total
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flux
i
load
i