Patent ID: 8650894

Claim:
A method for modulating capacity in a compressor for a heat pump operating in a heating mode, the method comprising: providing a controller operable to provide control signals to generate a plurality of preselected output frequencies for a motor of a compressor; measuring an outdoor ambient temperature; comparing the measured outdoor ambient temperature to a plurality of temperature setpoints, each temperature setpoint of the plurality of temperature setpoints being associated with a preselected output frequency of the plurality of preselected output frequencies, each preselected output frequency of the plurality of preselected output frequencies progressively increases in value as each associated temperature setpoint of the plurality of temperature setpoints progressively decreases in value; selecting a preselected output frequency of the plurality of preselected output frequencies based on the measured outdoor ambient temperature being less than a temperature setpoint of the plurality of temperature setpoints, the selected preselected output frequency being associated with a minimum temperature setpoint of the temperature setpoints greater than the measured outdoor ambient temperature; operating the motor at the selected preselected output frequency and a corresponding voltage to produce a corresponding output capacity for the compressor.