Hz Sensorless Vector Control - Omron SYSDRIVE RX Series User Manual

Note 1: Make sure that the carrier frequency (b083) is not lower than 2.1 kHz. If the carrier frequency is lower than
2.1 Hz, the Inverter does not operate normally.
Note 2: To use lower rank motor size than the Inverter, set a torque limit value (b041 to b044), while keeping the
value α, calculated with the following formula, at 200% or lower. Otherwise, the motor may burn out.
α = Torque limit set value × (Inverter capacity) / (Motor capacity)
(Example) If the Inverter capacity is 0.75 kW and the motor capacity is 0.4 kW, the torque limit set value for α =
200%, calculated with the above formula, is as follows: Torque limit set value (b041 to b044) = α ×
(Motor capacity) / (Inverter capacity) = 200% x (0.4 kW)/(0.75 kW) = 106%

0-Hz Sensorless Vector Control

•This function enables high-torque operation in the 0-Hz range (0- to 3-Hz frequency reference).
This control method is particularly suitable for applications such as an elevating system, which
requires sufficient torque in a low-frequency range at startup (e.g. crane, hoist).
•To use this function, set V/f characteristics selection A044/A244 to "04".
•To use this function, make sure that the motor parameter settings are suitable for your motor.
(Refer to "Motor Parameter Selection" (page 4-112).)
•The parameters for 0-Hz SLV control are as follows:
•In 0-Hz limit H060/H260, you can set a current value used for constant current control in the 0-
Hz range (generally, 3.0 Hz or lower). This parameter is expressed as a ratio of the output current
to the Inverter's rated current.
•In 0-Hz SLV startup boost amount H061/H261, you can set a current boost amount at startup in
the 0-Hz range. A current value expressed as a ratio to the Inverter's rated current is added to
the current value set in H060/H260 at startup only.
Parameter No. Function name
H060/H260 Limit at 0 Hz
Boost amount at SLV
H061/H261
startup, 0 Hz
•Note the following before use:
•Select an Inverter with one rank higher in capacity than the motor's.
•Sufficient characteristics may not be obtained if you select a motor size two or more ranks lower
than the maximum applicable motor size.
•In the 0-Hz sensorless control mode, the digital command board (3GAX-DI01) cannot be used.
Data
0.0 to 100.0:
Current limit in low frequency range
0. to 50.: Current boost amount at startup
4-2 Function Mode
Default setting Unit
100.0 %
50. %
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