ABB ACS580 Series, Руководство по прошивке

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Program features 113

Torque control performance figures
The drive can perform precise torque control without any speed feedback from the
motor shaft. The table below shows typical performance figures for torque control.

Power loss ride-through
See section Undervoltage control (power loss ride-through) on page 122 .

U/f ratio
The U /f function is only available in scalar motor control mode, which uses frequency
control.
The function has two modes: linear and squared.
In linear mode, the ratio of voltage to frequency is constant below the field weakening
point. This is used in constant torque applications where it may be necessary to
produce torque at or near the rated torque of the motor throughout the frequency
range
In squared mode (default), the ratio of the voltage to frequency increases as the
square of the frequency below the field weakening point. This is typically used in
centrifugal pump or fan applications. For these applications, the torque required
follows the square relationship with frequency. Therefore, if the voltage is varied
using the square relationship, the motor operates at improved efficiency and lower
noise levels in these applications.
The U /f function cannot be used with energy optimization; if parameter 45.11 Energy
optimizer is set to Enable , parameter 97.20 U/F ratio is ignored.
t (s)
T
N
= rated motor torque
T
ref
= torque reference
T
act
= actual torque
Torque control Performance
Non-linearity ± 5% with nominal
torque
(± 20% at the most
demanding operating
point)
Torque step rise time < 10 ms with nominal
torque
100
< 5 ms
90
10
T
ref
T
act
T
T
N
(%)
ACS580 FW.book Page 113 Wednesday, September 21, 2016 9:48 PM