Overview Of Vector Control; Hz Sensorless Vector Control - Omron RX Series User Manual

6 Vector Control
6-1

Overview of Vector Control

Induction motors have a characteristic that their output torque and rotation speed change depending on
the load.
The vector control function enables to output the output torque and rotation speed of induction motors
as the target values.
It calculates the output voltage and frequency of the inverter based on vector operations considering
with phases such as the current, voltage, and magnetic flux inside the motor.
The 3G3RX-V1 Series Inverter provides three types of vector controls as described below.
Use an appropriate control mode according to the torque and speed accuracy required by the load.
Sensorless Vector Control
The 3G3RX-V1 Series Inverter's sensorless vector control provides a high starting torque of 200% at
0.3 Hz.
It estimates the motor rotation speed based on the output current and voltage of the inverter to enable
such a high torque even at low speeds.
In addition to sensorless vector control, the inverter also provides the auto-tuning function (motor
rotation/no motor rotation).
The auto-tuning function enables you to set motor parameters without use of speed sensors (PG), so
you can easily use the sensorless vector control for your system.
Compared with conventional V/f control, sensorless vector control provides improved motor speed
accuracy (±0.5% maximum) and torque characteristics in the range of low to high speed.

0-Hz Sensorless Vector Control

The 3G3RX-V1 Series Inverter's 0-Hz sensorless vector control is designed to achieve a high starting
torque output of 150% especially in a 0-Hz range.
It is suitable particularly for elevating applications such as a crane and hoist that requires a high torque
at low frequencies when the brake is released.
Because of a high torque at 0 Hz, timing and other adjustments of the brake are fairly easy.
To use this control, however, use an inverter that is one size larger in capacity than the motor.
It is required to use an inverter that is one size larger in capacity than the motor to supply a sufficient
current at low speeds without error detection such as overcurrent, overvoltage and overload.
6 - 2 High-function General-purpose Inverter 3G3RX-V1 User's Manual (I578-E1)