Hitachi SJ Series, User Manual

Page: 221 / 786

12-9-4
Chapter 12 Inverter Function
12.9.3 Drive with V/f control (reducing
torque characteristics)
• To reduce the output voltage in accordance with
the fan/pump's characteristics in order to get a
higher energy-saving effect.
• To use in a more efficient state with less vibration
and lower noise, because no large torque is
necessary at lower speeds.
V/f control (reducing torque characteristics)
• Suitable for applications, such as a fan/pump, that
require no large torque at a low-speed range.
Parameter
• When a motor is hunting and vibrating, an
adjustment of the stability constant [HA110] may
improve the state of the motor.
• As the output voltage is low at a low-speed range,
improved efficiency, lower noise, and less vibration
can be expected.
Period a: Constant torque characteristics are
employed for a period from 0 Hz to the
frequency that is 10% of the base
frequency. (e.g.) A 60-Hz base frequency
yields constant torque characteristics for a
range from 0 to 6 Hz.
Period b: Reducing torque characteristics are
employed for a period from the frequency
that is 10% of the base frequency to the
base frequency. For a given frequency, the
voltage on the curve of the 1.7th power to
the given frequency is outputted.
Period c: The voltage has constant-output
characteristics for a range from the base
frequency to the maximum frequency.
Item Parameter Data Description
Control mode [AA121] 01
To be used with the V/f control and the
reducing torque characteristics (IM).
Stability
constant
[HA110] 0~1000(%)
To adjust the control for reducing the hunting
of motors.
Base frequency [Hb104]
10.00 to the maximum
frequency (Hz) To set the base frequency of motors.
Maximum
frequency
[Hb105]
Base frequency to 590.00
(Hz) To set the maximum frequency of motors.
Motor's rated
voltage
[Hb106] 1~1000 (V)
Set the rated voltage of motors.
Ｑ
Ａ
！
Command
frequency
(Hz)
Output voltage (V)
Base frequency
Maximum
frequency
0
10% of the base
frequency
1.7th power (f
1.7
)
Proportional
a b
c
Rated
voltage