• Possibility to supply nominal voltage to the motor even when the supply voltage of
the drive is below the motor nominal voltage. Example: A drive that is connected to
415 V can supply 460 V to a 460 V motor.
• Compensation of a voltage drop due to an output filter, motor cable or input supply
cables.
• Increased motor torque in the field weakening area (that is, when the drive operates
the motor in the speed range above the motor nominal speed).
Use case examples
Example 1: Full motor voltage regardless of supply voltage fluctuations
Supply voltage is 380 V, motor nominal voltage is 400 V. To get motor nominal voltage
at nominal speed regardless of the supply voltage fluctuations:
1. Calculate the required user DC voltage reference: 400 V × √2 = 567 V DC.
2.
Set the value of parameter 94.22 to 567 V.
3.
Make sure that the value of parameter 99.7 is set to 400 V.
Example 2: Sine filter at the output of the drive
The drive is equipped with a sine filter at the output. Motor cable length is 300 m (984 ft).
Estimated voltage loss across the filter and cable is 40 V. Motor nominal voltage is
400 V.
To compensate for the 40 V voltage loss at the nominal speed:
1. Calculate the required voltage at the drive output before the sine filter to compensate
for the voltage drop: 400 V + 40 V = 440 V.
2. Calculate the required user DC voltage reference: 440 V × √2 = 622 V.
3.
Set the value of parameter 94.22 to 622 V.
If the drive is configured to operate in DTC motor control mode and the ID run is
performed with the output filter and motor cable connected, no other configuration is
needed. The DTC motor control will take care of the estimated losses and boost drive
output voltage without getting limited by parameter 99.7.
If the drive is configured to operate in the scalar motor control mode, change the value
of parameter 99.7 to 440 V to allow the motor control to go up to 440 V at the drive
output at nominal speed.
Note: In scalar motor control mode, the output voltage can alternatively be increased
by adjusting the U/f curve: by setting parameter 97.7. The value of 97.7, can be calculated
as the ratio of the desired voltage and the nominal voltage. In this example, the ratio is
440 V / 400 V = 110%. Set the value of 97.7 to 110% and leave motor nominal voltage
as 400 V.
Program features 85
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