Firmware ≤ 11.00 - DMS 8.0 EN - 10/2011 L 129
8400 StateLine C | Reference manual
Motor control (MCTRL)
V/f characteristic control (VFCplus)
5.4.2.1 Defining the V/f characteristic shape
In principle, four different characteristic shapes can be stipulated:
1. Linear V/f characteristic:
For drives for a constant, speed-independent load torque.
2. Quadratic V/f characteristic:
For drives with a load torque curve which is quadratic or in relation to speed. Quadratic
V/f characteristics are preferred in the case of centrifugal pumps and fan drives.
3. Freely definable V/f characteristic (from version 04.00.00):
For drives that require adaptation of the magnetising current by means of the output
speed. The freely definable V/f characteristic can be used e.g. for operation in
conjunction with special machines such as reluctance motors in order to suppress
oscillations at the machine or to optimise energy consumption.
[5-3] Principle of a linear V/f characteristic (on the left) and a quadratic V/f characteristic (on the right)
4. Linear V/f characteristic with voltage reduction (from version 10.00.00):
For drives which often work in partial load operation, the energy-saving V/f
characteristic control (VFCplusEco) offers the opportunity to reduce the voltage at low
load in order to save energy. At higher loads, the voltage reduction is cancelled and a
linear characteristic is caused.
The V/f characteristic shape is defined by selecting the corresponding motor control mode
in C00006
:
Tip!
• You can find detailed information on freely definable V/f characteristics in the
subchapter entitled "Defining a user-defined V/f characteristic
". ( 140)
• You can find detailed information on the linear V/f characteristic with voltage
reduction in the chapter entitled "V/f characteristic control - energy-saving
(VFCplusEco)". ( 144)
V/f characteristic shape Motor control to be selected (C00006)
Linear V/f characteristic 6: VFCplus: V/f linear
Square-law V/f characteristic 8: VFCplus: V/f quadr
User-definable V/f characteristic 10: VFCplus: V/f definable
Linear V/f characteristic with voltage reduction 11: VFCplusEco: V/f energy-saving
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