Hitachi SJ2002 Series, Instruction Manual

Page: 97 / 306

SJ200
2
Inverter
Conf
igur
ing
Dr
iv
e P
a
ra
m
e
ters
3–17
Torque Control Algorithms
The inverter generates the motor output
according to the V/f algorithm or the intelli-
gent sensorless vector control algorithm.
Parameter A044 selects the inverter algorithm
for generating the frequency output, as shown
in the diagram to the right (A244 for 2nd
motor). The factory default is 02 (intelligent
sensorless vector control).
Review the following descriptions to help you
choose the best torque control algorithm for
your application.
• The built-in V/f curves are oriented toward developing constant torque or variable
torque characteristics (see graphs below).
• Intelligent sensorless vector control (iSLV) calculates an ideal torque vector based on
current motor position, winding currents, and so on. It is a more robust and precise
control method than the V/f control methods. Using the iSLV mode, the inverter
automatically adapts to the electrical characteristics of your motor.
The motor load current is affected not only by the mechanical load, but also by the
particular torque control algorithm in use (selected by A044 and A244). If your SJ200
Series inverter uses parameter A044/A244 = 02 (intelligent sensorless vector control)
and you change the parameter so that A044/A244 = 00 (constant torque) or = 01
(reduced torque), then the inverter output current (motor current) may increase. This
condition can easily cause an overload/over-current fault. If such a fault occurs, be sure
to adjust A042/A242, A043/A243. Example settings: A042 = 1.8, and A043 = 10.0.
Constant and Variable (Reduced) Torque – The graph below (left) shows the constant
torque characteristic from 0Hz to the base frequency A003. The voltage remains
constant for output frequencies higher than the base frequency. The graph below (right)
shows the general variable (reduced) torque curve. The range from 0Hz to the base
frequency is the variable characteristic.
Output
Inverter Torque Control Algorithms
V/f control,
constant torque
V/f control,
variable torque
00
01
02
A044
Intelligent sensor-
less vector control
( i SLV)
Constant torque A044 = 00
V
100%
Hz
0
Variable torque A044 = 01
V
100%
Hz
0
Base
freq.
Max.
freq.
Base
freq.
Max.
freq.