Hitachi SJ Series User Manual page 221

Chapter 12
12.9.3 Drive with V/f control (reducing
torque characteristics)
Ｑ
• 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.
Ａ
V/f control (reducing torque characteristics)
• Suitable for applications, such as a fan/pump, that
require no large torque at a low-speed range.
Output voltage (V)
Rated
voltage
Proportional
0
10% of the base Base frequency
frequency
a
b
Parameter
Item Parameter
Control mode [AA121]
Stability
[HA110]
constant
Base frequency [Hb104]
Maximum
[Hb105]
frequency
Motor's rated
[Hb106]
voltage
1.7
1.7th power (f )
Command
frequency
Maximum
frequency
c
Data
01
0~1000(%)
10.00 to the maximum
frequency (Hz)
Base frequency to 590.00
(Hz)
1~1000 (V)
！
• 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
(Hz)
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.
To be used with the V/f control and the
reducing torque characteristics (IM).
To adjust the control for reducing the hunting
of motors.
To set the base frequency of motors.
To set the maximum frequency of motors.
Set the rated voltage of motors.
12-9-4
Inverter Function
Description