Sensorless Vector Control - Omron 3G3MX2 User Manual

"H" Group: Motor Constants Functions
3-8-2

Sensorless Vector Control

Status
Powering
Regeneration
Starting
Decelerating
Low frequency
operation
174
This sensorless vector control enables the inverter to accurately operate the
motor with a high starting torque, even at low speed. It estimates and controls
the motor speed and output torque based on the inverter output voltage, out-
put current, and the set motor constants on the inverter. To use this function,
specify "" for the V/F characteristic curve selection (/).
In prior to use this function, be sure to make optimum setting of the motor con-
stants, which is described before.
When using this function, observe the following precautions:
1. If you use the inverter to drive a motor of which the capacity is two class
lower than the maximum applicable capacity of the inverter, you may not
be able to obtain adequate motor characteristics.
2. If you cannot obtain the desired characteristics from the motor driven un-
der the SLV control, readjust the motor constants according to the symp-
tom, as described in the table below.
Symptom
Momentary speed variation is
negative
Momentary speed variation is
positive
Torque is insufficient at low
speed (~ few Hz)
Motor generates an impact at
start
Motor runs backward for short
moment at start
Motor runs unsteadily
Motor rotation is unstable
Note Note 1) When driving a motor of which the capacity is one class lower than
the inverter, adjust the torque limit ( to ) so that the value "" calcu-
lated by the expression below does not exceed 200%. Otherwise, the motor
may not be burnt.
 = "torque limit" x (inverter capacity) / (motor capacity)
(Example) When the inverter capacity is 0.75 kW and the motor capacity is
0.4 kW, the torque limit value is calculated as follows, based on the assump-
tion that the value should be 200%:
Torque limit ( to )
Adjustment method
Increase the motor constant R2 step by step
from the set value up to 1.2 times of the set
value
Decrease the motor constant R2 step by step
from the set value up to 0.8 times of the set
value
Increase the motor constant R1 step by step
from the set value up to 1.2 times of the set
value
Increase the motor constant Io step by step
from the set value up to 1.2 times of the set
value
Reduce the motor constant J from the set value /
Decrease the speed response factor
Set 01 (enable) on reverse run protection func-
tion (b046)
Decrease the speed response factor
Decrease the motor constant J from the set
value
Increase the speed response factor
Increase the motor constant J from the set
value
=  x (motor capacity) / (inverter capacity)
= 2.0 x (0.4kW)/(0.75kW) = 106%
Section 3-8
Adjustment
item
/
/
/
/
/

/
/
/
/