Yaskawa VS-626 MC5 - Manual (Page 154)

Advanced Operation
7.2.3 Operation Selection when Output Voltage Saturated
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7.2.3 Operation Selection when Output Voltage Saturated
The Inverter cannot output a voltage that is higher than the input voltage. If the output voltage command
to the motor (monitor constant U1--06) exceeds the input voltage in the high--speed region, the output volt-
age becomes saturated, and precise torque control is not longer possible during flux vector control.
Select noe of the following methods to insure precise torque control.
J Limited Output Voltage Operation: C3--06
User
Change
during Setting Factory
Valid Access Levels User
Constant
Number
Name
during
Opera-
tion
Setting
Range Unit
Factory
Setting Open Loop
Vector
Flux Vector
C3--06
Limited output voltage
operation
0 1 1 0 A A
D Settings
Setting Function
0 Disables limited output voltage operation.
1 Enables limited output voltage operation.
D If the limited output voltage operation is disabled and output voltage becomes saturated, the output
current does not change. However, torque control precision is no longer possible.
Enable limited output voltage operation if precise torque control is required.
D If the limited output voltage operation is enabled, the magnetic flux current of the motor is automatical-
ly controlled, and the output voltage command itself is limited, which maintains precies torque control.
Check the Inverter current margins as the output current will be maximum 10% higher (with a rated
load) than when limited output voltage operation is disabled.
Note 1.C3--06 does not need to be changed if the Unit is used only at mediun or low speeds, or
when the power supply voltage is 10% more higher than the rated voltage for the motor,
or when torque control precision in the high--speed region is not required.
2. When the power supply voltage is too low for the rated motor voltage, precise torque con-
trol will not be maintained even if limited output voltage operation is enabled.
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