Abstract: A system includes a refrigerant compressor, an electric motor and configured to drive the refrigerant compressor, and a controller. The controller is configured to operate the compressor in a liquid clearing start mode where electrical current through the motor is prevented from exceeding a predetermined current limit for a period of time not to exceed a predetermined period of time, and is configured to operate the compressor in a run mode in response to determining the motor exceeds a predetermined speed threshold at or before expiration of the predetermined period of time, wherein the run mode does not prevent electrical current through the motor from exceeding said predetermined current limit.

Abstract: A system includes a refrigerant circuit including a compressor, a condenser, an expander, an electric motor configured to drive the compressor, and a controller configured to control a motor drive to drive the electric motor. The controller is configured to first evaluate whether the compressor is idle based upon a control state of the controller being configured not to operate the motor drive to drive the motor, second, in response to an affirmative evaluation that the compressor is idle, evaluate a risk of undesired or un-commanded compressor rotation based upon a combination of two or more system conditions, each of the two or more system conditions indicating the risk of undesired or un-commanded compressor rotation, and third, in response to an affirmative evaluation of the risk of undesired or un-commanded compressor rotation, control the motor drive to oppose rotation of the compressor.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

Abstract: Unique apparatuses, methods, and systems of opposing, limiting, and/or preventing undesired or un-commanded compressor rotation are disclosed. One exemplary embodiment is an HVACR system comprising a variable frequency drive configured to drive an electric motor to rotate a screw compressor or scroll compressor. A controller is configured to monitor various aspects of the system and to control the drive. When a condition indicative of potential undesired or un-commanded compressor rotation is identified, the controller commands the variable frequency drive to control the motor to limit and preferably prevent compressor rotation. One technique comprises shorting switches of the drive to a DC bus rail to allow back EMF induced current in the motor windings to be dissipated through winding resistance thus providing a damping force. Another technique comprises controlling the inverter to insert a DC current into the motor to cause the motor to align to and hold a particular position.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

Abstract: Apparatuses, methods, and systems offering enhanced robustness, efficiency and rated voltage operability for refrigerant compressor drives are disclosed. An exemplary embodiment is a method of operating a variable frequency drive. The method includes operating the drive over a first operating range to provide at least a desired operating speed and minimize d-axis current, operating the drive over a second operating range including injecting d-axis current to provide at least the desired operating speed, operating the drive over a third operating range at a de-rated speed less than the desired operating speed. In the first operating range the drive input voltage is greater than a first value. In the second operating range the drive input voltage is lower than the first value and greater than a second value. In the third operating range the drive input voltage is lower than the second value.

Abstract: Unique apparatuses, methods, and systems of opposing, limiting, and/or preventing undesired or un-commanded compressor rotation are disclosed. One exemplary embodiment is an HVACR system comprising a variable frequency drive configured to drive an electric motor to rotate a screw compressor or scroll compressor. A controller is configured to monitor various aspects of the system and to control the drive. When a condition indicative of potential undesired or un-commanded compressor rotation is identified, the controller commands the variable frequency drive to control the motor to limit and preferably prevent compressor rotation. One technique comprises shorting switches of the drive to a DC bus rail to allow back EMF induced current in the motor windings to be dissipated through winding resistance thus providing a damping force. Another technique comprises controlling the inverter to insert a DC current into the motor to cause the motor to align to and hold a particular position.

Abstract: Apparatuses, methods, and systems offering enhanced robustness, efficiency and rated voltage operability for refrigerant compressor drives are disclosed. An exemplary embodiment is a method of operating a variable frequency drive. The method includes operating the drive over a first operating range to provide at least a desired operating speed and minimize d-axis current, operating the drive over a second operating range including injecting d-axis current to provide at least the desired operating speed, operating the drive over a third operating range at a de-rated speed less than the desired operating speed. In the first operating range the drive input voltage is greater than a first value. In the second operating range the drive input voltage is lower than the first value and greater than a second value. In the third operating range the drive input voltage is lower than the second value.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.