Patent ID: 9590540
Date: 2017-03-07
CPC Classifications: F02M,H02M,H02P

Claim:
1. A method for controlling a variable speed drive (VSD) using a hybrid pulse width modulation (PWM) method comprising: providing a compressor, a condenser, and an evaporator connected in a closed refrigerant loop; a motor connected to the compressor to power the compressor; and the variable speed drive connected to the motor, the variable speed drive being configured to receive an input AC power at a fixed input AC voltage and a fixed input frequency and provide an output power at a variable voltage and variable frequency to the motor; determining an optimal threshold input current value for the variable speed drive; determining an actual input current value of the variable speed drive; comparing the actual current input value of the VSD with an optimal threshold current input value of the VSD; applying a first PWM method comprising a continuous PWM method in response to the input current being less than the predetermined threshold input current value; and applying a second PWM method comprising a discontinuous PWM method in response to the input current being greater than the predetermined threshold value.