CPC H02P 27/06 (2013.01) [H02P 23/20 (2016.02)] | 20 Claims |
1. A method of operating a variable frequency drive (VFD), the method comprising:
operating a converter of the VFD in a ramp-up mode to produce an AC output voltage for ramping up a speed of a motor;
determining a loading of the converter in the ramp-up mode; and
conditioning transfer of the motor from the ramp-up mode to a bypassed mode in which the converter is bypassed and an AC source is connected to the motor on whether the determined loading in the ramp-up mode meets a criterion.
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11. A system comprising:
a converter configured to drive a motor;
a bypass switch configured to bypass the converter and connect an AC source to the motor; and
a control circuit configured to operate the converter in a ramp-up mode to produce an AC output voltage for ramping up a speed of the motor, to determine a loading of the converter in the ramp-up mode and to condition transfer of the motor from the ramp-up mode to a bypassed mode in which the bypass switch bypasses the motor and connects an AC source to the motor based on whether the determined loading in the ramp-up mode meets a criterion.
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