To take the DC voltage boost function in use, adjust the user DC voltage reference
value in parameter 94.22. The drive follows the user reference If it is greater than
the measured DC voltage of the drive at the time of power up.
Benefits of the DC voltage boost
• possibility to supply nominal voltage to the motor even when the supply voltage
of the drive is below the motor nominal voltage level
• compensation of voltage drop due to output filter, motor cable or input supply
cables
• increased motor torque in the field weakening area (ie, when the drive operates
the motor in the speed range above the motor nominal speed)
• possibility to use a motor with higher nominal voltage than the actual supply
voltage of the drive. Example: A drive that is connected to 415 V can supply
460 V to a 460 V motor.
Impact of DC voltage boost on input current
When the DC voltage is boosted, the drive can be drawing more input current than
what is rated in the type designation label. Derating is needed:
• when the motor is running at the field weakening area or close to it and the
drive is running at nominal load or close to it
• when the situation lasts long
• when the boost is more than 10%.
The rise of the input current can heat the fuses. If there are brief low line situations
when the drive boosts voltage significantly, there is a risk for nuisance fuse blowing
of smaller AC line fuses.
For more information, refer toACH580-31, ACQ580-31, ACH580-34 and ACQ580-34
drives product note on DC voltage boost (3AXD50000769407 [English]).
￭
DC connection
You can connect an external brake chopper to the drive via the DC terminals. See
Resistor braking (page 243).
WARNING!
Do not connect the drive DC link to a common DC system. The drive will get
damaged.
Operation principle 33
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