Sensorless Vector Control - Hitachi WJ200 Series Instruction Manual

Sensorless Vector Control

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, output current, and the set motor
constants on the inverter. To use this function, specify "03" for the V/F characteristic
curve selection (A044/A2444).
In prior to use this function, be sure to make optimum setting of the motor constants,
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 under the
SLV control, readjust the motor constants according to the symptom, as described in
the table below.
Status Symptom
Powering Momentary speed variation is
negative
Momentary speed variation is
positive
Regeneration Torque is insufficient at low
speed (~ few Hz)
Starting Motor generates an impact at
start
Motor runs backward for short
moment at start
Decelerating Motor runs unsteadily
Low frequency Motor rotation is unstable
operation
Note 1) When driving a motor of which the capacity is one class lower than the inverter,
adjust the torque limit (b041 to b044) so that the value "α" calculated by the
expression below does not exceed 200%. Otherwise, the motor may not be burnt.
α = "torque limit" x (inverter capacity) / (motor capacity)
(Example) When the inverter capacity is 0.75kW and the motor capacity is 0.4kW,
Torque limit (b041 to b044) = α x (motor capacity) / (inverter capacity)
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 function
(b046)
Decrease the speed response factor
Decrease the motor constant J from the set value
Increase the motor constant J from the set value
Increase the speed response factor
the torque limit value is calculated as follows, based on the
assumption that the value α should be 200%:
= 2.0 x (0.4kW)/(0.75kW) = 106%
3−107
Adjustment
item
H021/H221
H021/H221
H020/H220
H023/H223
H024/H224
H005/H205
b046
H005/H205
H024/H224
H024/H224
H005/H205