User`s guide

83
CHAPTER 6
6.1
SYMBOLS
DETAILEDPARAMETERDESCRIPTION
This chapter describes in detail all CFW-08 parameters and
functions.
Some symbols used in this chapter are presented below:
AIx
=Analog input number x.
AO
=Analog output.
DIx
= Digital input number x.
F*
= Frequency reference. This is the frequency value that
indicates the desired motor speed at the inverter output.
F
e
= Inputfrequencyofthe acceleration and decelerationramp.
F
max
= Maximum output frequency, defined at P134.
F
min
= Minimum output frequency, defined at P133.
F
s
= Output frequency - frequency applied to the motor.
I
nom
= Rated inverter outputcurrent (rms), inAmpères (A).This
value is defined in P295.
I
s
= Inverter outputcurrent.
I
a
=Active currentat inverter output, i.e.,it is the component of
the total motor current proportional to active electric power
absorbed by the motor.
RLx
= Relayoutput number x.
U
d
= DC link voltage in the DC link circuit.
This section describes the main concepts related to the
CFW-08
frequency inverter.
As already informed in
item
2.3, CFW-08 has in the same
product a V/F control and a sensorless vector control (VVC:
“voltage vector control”).
The user must choose one of them. Please find below a
description of each control mode.
This control mode is based on the constant V/F curve
(P202 = 0 - linear V/F curve). Itsperformance is limited at low
frequencies as function of the voltage drop in the stator
resistance, that causes a significant magnetic flow reduction
in the motor air gap and consequently reducing the motor
torque. This deficiency should be compensated by using
manual and automatic boost torque (IxR compensations),that
are set according to the parameters P136 or P137.
Inmostapplications (for instance:centrifugal pumps and fans)
the setting of these functions is enough to obtain the required
performance. But there
are applications that require a more
sophisticatedcontrol.In thesecases
it's recommended the use
of the sensorless vector control, that will be described in the
item 6.2.3 - Vector Control (VVC).
6.2
INTRODUCTION
6.2.2
V/F Control
6.2.1
Control Modes
(V/F and Vector)