Patent ID: 9595905
Date: 2017-03-14
CPC Classifications: F04B,F25B,H02P

Claim:
1. A method comprising: providing a variable frequency drive configured to operate a motor to drive a refrigerant compressor using power from a power source; commanding operation of the drive over a first operating range to provide at least a desired operating speed and minimize d-axis current, wherein over the first operating range the drive input voltage is greater than a first value in a rated voltage range; commanding operation of the drive over a second operating range including injecting d-axis current to provide at least the desired operating speed, wherein over the second operating range the drive input voltage is lower than the first value and greater than a second value in the rated voltage range; and commanding operation of the drive over a third operating range at a de-rated speed less than the desired operating speed, wherein over the third operating range the drive input voltage is lower than the second value.