US 12,378,969 B2
Controller and drive circuit for electric motors
Ludovic Andre Chretien, Columbia City, IN (US)
Assigned to Regal Beloit America, Inc., Milwaukee, WI (US)
Filed by Regal Beloit America, Inc., Beloit, WI (US)
Filed on Apr. 21, 2022, as Appl. No. 17/725,873.
Claims priority of provisional application 63/177,715, filed on Apr. 21, 2021.
Prior Publication US 2022/0341434 A1, Oct. 27, 2022
Int. Cl. F04B 49/02 (2006.01); F04B 35/04 (2006.01); F04B 49/24 (2006.01); F04D 27/00 (2006.01); H02P 27/06 (2006.01)
CPC F04D 27/00 (2013.01) [F04D 27/009 (2013.01); H02P 27/06 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A control system for an electric motor in a compressor system, the control system comprising:
a motor controller coupled directly in communication with an inverter of the electric motor, a pressure equalization mechanism, and one or more switches, the motor controller configured to:
control the inverter to supply variable frequency power to the electric motor from the inverter;
determine when to transition from supplying variable frequency power to supplying line frequency power to the electric motor;
estimate a maximum speed currently achievable by the electric motor based on at least one input parameter;
if the estimated maximum speed does not meet a threshold speed for transitioning to supplying line power, engage the pressure equalization mechanism to at least partially reduce a pressure differential developed between a suction portion and a discharge portion of the compressor system during the transition from supplying variable frequency power to supplying line frequency power; and
if the estimated maximum speed meets the threshold speed, control the one or more switches to apply line frequency power to at least one winding of the electric motor.