9-1
9
Scalar Control (V/f)
9 SCALAR CONTROL (V/F)
It consists of a simple control based on a curve that links output voltage and frequency. The inverter operates
as a voltage source, generating frequency and voltage values according to that curve. It is possible to adjust
this curve to standard 50 Hz or 60 Hz motors or to special ones through the adjustable V/f curve. Refer to the
block diagram at the
.
The advantage of the V/f control is that due to its simplicity just a few settings are necessary. The start-up is fast
and simple, and the factory settings require generally few or no modifications.
V
V
Reference
PWM
PWM
Speed
P0202 = 2 = Adjustable V/f
P0202 = Type of Control
Total Reference
(Refer to
)
I
s
= Output Current
TRANSF.
I active
P0139
V
f
P0202 = 0 or 1 = V/f
P0142
P0143
P0144
P0138
P0137
Speed
Speed
Speed
P0146 P0145
Automatic Torque
BOOST
Slip Compensation
V
V
V
P0136
Figure 9.1 -
V/f control block diagram
The V/f or scalar control is recommended for the following cases:
Operation of several motors with the same inverter (multimotor operation).
The motor rated current is less than 1/3 of the inverter rated current.
The inverter is, for test purposes, enabled without motor or with a small motor and no load.
The scalar control can also be used in applications that do neither require fast dynamic response, nor accuracy
in the speed regulation, and also do not require high starting torque (the speed error is a function of the motor
slip, and by programming the parameter P0138 – Slip Compensation – it is possible to get a accuracy of
approximately 1 % at the rated speed with the load variation).
Summary of Contents for CFW-11 Series
Page 2: ......
Page 54: ...2 4 2 General Information ...
Page 58: ...About the CFW 11 3 3 4 ...
Page 74: ...Inverter Model and Accessories Identification 5 14 6 ...
Page 86: ...Inverter Model and Accessories Identification 6 12 6 ...
Page 94: ...Available Control Types 8 2 8 ...
Page 118: ...VVW Control 10 8 10 ...
Page 182: ...Functions Common to All the Control Modes 12 26 12 ...
Page 220: ...Dynamic Braking 14 4 14 ...