Motor controller for draft inducer motor in a furnace and method of use

A method of controlling a motor that operates a blower in a furnace, the method comprising:

• storing, in a memory, a motor speed profile for operation of the motor during a plurality of predefined time periods associated with a plurality of discrete, sequential furnace stages in an order of an ignition stage, a stabilization stage following the ignition stage, and a combustion stage following the stabilization stage, the motor speed profile comprising a plurality of predefined time periods, the plurality of predefined time periods comprising:
• a first predefined time period for ramping motor speed to a predefined first motor speed, the first motor speed defined for the ignition stage, the first predefined time period comprising a first predefined amount of time;
• a second predefined time period for operating the motor at the first motor speed during the ignition stage, the second predefined time period comprising a second predefined amount of time;
• and
• a third predefined time period for ramping motor speed from the first motor speed to a predefined second motor speed, the second motor speed being higher than the first motor speed and defined for the stabilization stage, the third predefined time period comprising a third predefined amount of time;
• and
• operating, by a processor of a motor controller for the motor, the motor in accordance with the motor speed profile during the plurality of predefined time periods,
• wherein the second motor speed during the stabilization stage is lower than a predefined third motor speed at which the motor is controlled to operate during the combustion stage, and wherein maintaining motor speed of the motor at the second speed for a duration of the stabilization stage is configured to stabilize burners of the furnace and reduce temperature differences in the furnace before advancing the furnace to the combustion stage.

A furnace comprising:

• a blower;
• a motor coupled to the blower and operable to drive the blower to generate an airflow;
• and
• a motor controller comprising:
• a memory configured to store a motor speed profile for operation of the motor during a plurality of predefined time periods associated with a plurality of discrete, sequential furnace stages in an order of an ignition stage, a stabilization stage following the ignition stage, and a combustion stage following the stabilization stage, the motor speed profile comprising a plurality of predefined time periods, the plurality of predefined time periods comprising:
• a first predefined time period for ramping motor speed to a predefined first motor speed, the first motor speed defined for the ignition stage, the first predefined time period comprising a first predefined amount of time;
• a second predefined time period for operating the motor at the first motor speed during the ignition stage, the second predefined time period comprising a second predefined amount of time;
• and
• a third predefined time period for ramping motor speed from the first motor speed to a predefined second motor speed, the second motor speed being higher than the first motor speed and defined for the stabilization stage, the third predefined time period comprising a third predefined amount of time;
• and
• a processor operable to control the motor in accordance with the motor speed profile during the plurality of predefined time periods,
• wherein the second motor speed during the stabilization stage is lower than a predefined third motor speed at which the motor is controlled to operate during the combustion stage, and wherein maintaining motor speed of the motor at the second speed for a duration of the stabilization stage is configured to stabilize burners of the furnace and reduce temperature differences in the furnace before advancing the furnace to the combustion stage.