Emotron VS10 - V;F Characteristic Control (VFC)

7.2.1. V/f characteristic control (VFC)
The V/f characteristic control is a motor control for conventional frequency inverter
applications. It is based on a simple and robust control mode for the operation of
asynchronous motors with a linear or square-law load torque characteristic (e.g. fan).
Because of the minimal parameterisation effort, such applications can be commissioned
easily and quickly.
Preconditions
• The V/f characteristic control is only suitable for asynchronous motors.
• If you want to actuate a drive with a square-law V/f characteristic: please always check
whether the corresponding drive is suitable for operation with a square-law V/f
characteristic!
• From the motor nameplate data, at least the rated speed and rated frequency must be
entered, so that the inverter can calculate the correct number of pole pairs. Motor
data
 108
• The motor must only be actuated above the rated motor frequency/rated voltage if this
is
expressly approved by the motor manufacturer!
Details
This motor control type is activated by setting 0x2C00 (P300.00) = " V/f characteristic
control (VFC open loop) [6]".
• 0x2B00 (P302.00) provides different characteristic shapes which are described in detail
in
the following subchapters.
• Limiting factors for the V/f characteristic are rated mains voltage 0x2540:001 (P208.01),
minimum frequency 0x2915 (P210.00) and maximum frequency 0x2916 (P211.00).
Parameter
Name / value range / [default setting]
Info
0x2B00
(P302.00)
V/f characteristic shape
(V/f charac.shape)
•
Setting can only be changed if the inverter is
inhibi
ted.
Selection of the V/f characteristic shape for the adaptation to
different load profiles.
0
Linear
Linear characteristic for drives with constant load torque over the
speed.
 Linear V/f characteristic

111
1
Quadratic
Square-law characteristic for drives with a linear or square-law load
torque over the speed.
•
Square-law V/f characteristics are preferably used for
centrifugal
pumps and fan drives.
•
Please always check whether the corresponding drive is suitable
for
operation with a square-law V/f characteristic!
•
If your pump drive or fan drive is not suitable for operation with a
square-law V/f characteristic, use the linear V/f characteristic
instead.
 Square-law V/f characteristic

112
2
Multipoint
(from version 03.00)
Linear characteristics with an additional centre characteristic point for
the purpose of adaptation to specific load profiles.
 User-definable V/f characteristic

113
3
Eco
(from version 02.00)
Linear characteristic with energy optimisation in the partial load
operational range.
 V/f characteristic control energy-saving (VFC Eco)

114
0x2B01:001
(P303.01)
V/f shape data: Base voltage
(V/f shape data: Base voltage)
0 ... [230]* ... 5000 V
* Default setting depending on the size.
Base voltage and base frequency define the V/f ratio and thus the
gradient of the V/f characteristic.
•
The V/f base voltage is usually set to the rated motor
voltage
0x2C01:007 (P320.07).
•
The V/f base frequency is usually set to the rated motor
frequency
0x2C01:005 (P320.05).
0x2B01:002
(P303.02)
V/f shape data: Base frequency
(V/f shape data: Base frequency)
Device for 50-Hz mains: 0 ... [50]* ... 1500 Hz
Device for 60-Hz mains: 0 ... [60]* ... 1500 Hz
* Default setting depending on the size.