Controller and drive circuit for electric motors
AssigneeRegal Beloit America, Inc.
InventorLudovic Andre Chretien
Life of this patent
Estimating the term…
Abstract
A control system for an electric motor in a compressor system includes a processing system configured to control an inverter to supply variable frequency power to the electric motor from the inverter. The processing system is configured to determine when to transition from supplying variable frequency power to supplying line frequency power to the electric motor. The processing system is configured to engage a pressure equalization mechanism to at least partially reduce a pressure differential developed between a suction portion and a discharge portion of the compressor system. The processing system is configured to apply line frequency power to at least one winding of the electric motor.
Claims18
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.
A method for controlling an electric motor in a compressor system, the method performed by a motor controller coupled directly in communication with an inverter of the electric motor, a pressure equalization mechanism, and one or more switches, the method comprising:
- controlling the inverter to supply variable frequency power to the electric motor from the inverter;
- determining when to transition from supplying variable frequency power to supplying line frequency power to the electric motor;
- estimating 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, engaging 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, controlling the one or more switches to apply line frequency power to at least one winding of the electric motor.
A compressor system comprising:
- an electric motor;
- and
- 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.
Dependencies are inferred from the claim text.