DISCRETE FREQUENCY OPERATION FOR UNIT CAPACITY CONTROL

摘要

A variable speed electric drive for use in refrigerant systems (20) includes an electric motor (40) for driving an associated component (22) at a variable speed that is a function of an operating frequency of the motor (40); and a control (42) for supplying alternating discrete drive frequencies to the electric motor to provide a continuously variable speed drive of the associated component (22). The control (42) cycles the drive frequency to the electric motor (40) among the at least two discrete frequencies so that the variable average resultant speed at which the associated component (22) is driven is a function of a combination of the selected at least two discrete frequencies.