Hitachi SJ Series User Manual page 288

Chapter 12
12.11 Control Torque Based on
Loading
12.11.1 Speed Control and Torque Control
A
• There are several ways to control the motor torque
by having the inverter output as follows:
- Speed control: A method of output control by
having the motor speed follow a certain
frequency command and sending torque at a
certain speed, and
- Torque control: A method of output control by
changing the speed so that output torque follows
a certain command torque.
Control
Speed control
method
Control target Control is done to maintain the motor
speed per frequency command.
Operation Output will be controlled to maintain the
speed when loading is changed.
If loading becomes bigger, control will be
done to send a lager torque. When
loading becomes smaller, control will be
done to send a smaller torque.
• In the case of controlling by torque command, 08:
Sensorless vector control and 10: Sensor vector
control need to be selected in the [AA121] control
method.
• The torque limit function in speed control can be
used for 08: Sensorless vector control and 09:
Sensorless vector control in the zero speed area
and 10: Sensor vector control in the [AA121]
control method. In the zero speed area of 09:
Sensorless vector control in the zero speed area,
however, control to send torque is prioritized.
Torque control
Control is done to output the motor torque per
torque command.
When loading is changed, output will be
controlled to maintain the torque.
If loading becomes bigger, control will be done
to maintain the torque by raising the speed, etc.
If loading becomes smaller, control will be done
to maintain the torque by slowing the speed,
etc.
12-11-1
Inverter Functions