Mitsubishi Electric FR-A800, Instruction Manual

Page: 255 / 1042

Parameters Control method
FR-A800 5 - 75
5.2.5 Low-speed range torque characteristics
The torque characteristics in a low-speed range under PM sensorless vector control can be changed.
The low-speed range high-torque characteristic (current synchronization operation) is disabled for
PM motors other than MM-CF, even if "9999" is set.
When the low-speed range torque characteristic is enabled (Pr. 788 = "9999" initial value)
●
The high frequency superposition control provides enough torque in the low-speed range oper-
ation.
●
The low-speed range high-torque characteristic is only valid with an MM-CF motor.
When the low-speed range high-torque characteristic is disabled (Pr. 788 = "0")
●
The current synchronization operation reduces much motor noise compared with the high
frequency superposition control.
●
The torque in a low-speed range is low. Use this setting for an operation with light start-up load.
Low-speed range high-torque characteristic is set for the second motor (Pr. 747)
●
Use Pr. 747 "Second motor low-speed range torque characteristic selection" to switch the torque
characteristic according to the application or to switch among motors connected to one inverter.
●
The Pr. 747 becomes valid when the RT signal turns ON.
Pr. Name
Initial
value
Setting
range
Operation
788
G250
Low speed range torque
characteristic selection
9999
0
Disables the low-speed range torque characteristic
(current synchronization operation).
9999
Enables the low-speed range torque characteristic
(high frequency superposition control)
747
G350
Second motor low-speed
range torque characteristic
selection
9999
0
Disables the low-speed range torque characteristic
(current synchronization operation).
9999
Enables the low-speed range torque characteristic
(high frequency superposition control) while the RT
signal is ON.
NOTES Position control under PM sensorless vector control is not available when the current synchroniza-
tion operation is selected. Zero speed and servo lock are also disabled during current synchroniza-
tion operation.
For torque characteristics, refer to page 8-9.
RT signal is assigned to the terminal RT in the initial status. Set "3" in any of Pr. 178 to Pr. 189 (input
terminal function selection) to assign the RT signal to another terminal.
Changing the terminal assignment using Pr. 178 to Pr. 189 (input terminal function selection) may
affect the other functions. Set parameters after confirming the function of each terminal.
Parameters referred to
Pr. 178 to Pr. 189 (input terminal function selection) => page 5-422
PM PM PM