Method and apparatus for controlling a blower motor in an air handling system

System for conditioning air and for maintaining a desired rate of air flow of the conditioned air through a contained space with respect to static pressure therein, the system comprising:

• a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a blower in the contained space;
• means for generating a desired air flow rate signal which varies as a function of the desired rate of air flow;
• means for providing a motor torque signal representative of the torque of the motor;
• means for providing a speed signal representative of the speed of the motor;
• a microprocessor, responsive to both the desired air flow rate signal and the speed signal, for generating a desired torque signal which is a function of both the desired air flow rate signal and the speed signal;
• means for comparing the desired torque signal to the motor torque signal thereby to supply a comparison signal;
• and
• means for applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the blower is driven by varying the motor torque according to motor speed to maintain air flow in the contained space at substantially the desired rate of air flow substantially independent of variations in the static pressure.

Method for controlling an air handling system including a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a blower in the air handling system, the system further including means for generating a desired air flow rate signal which varies as a function of a desired rate of air flow, the method providing control of the blower speed over a range of static pressure variations to maintain the rate of air flow in the system at substantially the desired air flow rate, the method comprising the steps of:

• sensing the torque of the motor;
• sensing the speed of the motor;
• determining, by use of a microprocessor which is responsive to both the desired air flow rate signal and the sensed motor speed, a desired torque which is a function of both the desired air flow rate and the sensed motor speed;
• comparing the desired torque to the sensed motor torque;
• applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison;
• and
• commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the blower is driven by varying the motor torque according to motor speed to maintain air flow in the system at substantially the desired rate of air flow substantially independent of variations in the static pressure.

Apparatus for controlling a fluid handling system including a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a fluid pump in the fluid handling system, the system further including means for generating a desired system parameter signal which varies as a function of a desired value for the parameter, the apparatus providing control of the fluid pump over various operating conditions of the fluid handling system to maintain the parameter at substantially the desired value, the apparatus comprising:

• means for providing a motor torque signal representative of the torque of the motor;
• means for providing a speed signal representative of the speed of the motor;
• a microprocessor, responsive to both the desired parameter signal and the speed signal, for generating a desired torque signal which is a function of both the desired parameter signal and the speed signal;
• means for comparing the desired torque signal to the motor torque signal and for supplying a comparison signal in response to the comparison;
• and
• means for applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the fluid pump is driven by varying the motor torque according to motor speed to maintain the value of the parameter at substantially the desired value substantially independent of variations in the operating conditions of the fluid handling system.

Apparatus for controlling a fluid handling system including a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a fluid pump in the fluid handling system, the system further including means for generating a desired system parameter signal which varies as a function of a desired value for the parameter, and means for generating a motor current signal representative of the motor current, the apparatus providing control of the fluid pump over a range of various operating conditions of the fluid handling system to maintain the parameter at substantially the desired value, the apparatus comprising:

• means for providing a speed signal representative of the speed of the motor;
• a microprocessor, responsive to both the desired parameter signal and the speed signal, for generating a desired current signal which is a function of both the desired parameter signal and the speed signal;
• means for comparing the desired current signal to the motor current signal and for supplying a comparison signal in response to the comparison;
• and
• means for applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the fluid pump is driven to maintain the value of the parameter at substantially the desired value substantially independent of variations in the operating conditions of the fluid handling system.

System for conditioning fluid and for maintaining as substantially constant a desired parameter of the conditioned fluid through a contained space with respect to variations in operating conditions of the contained space, the system comprising:

• a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a fluid pump in the contained space;
• means for generating a desired system parameter signal which varies as a function of a desired value for the parameter;
• means for providing a motor torque signal representative of the torque of the motor;
• means for providing a speed signal representative of the speed of the motor;
• a microprocessor, responsive to both a desired parameter signal and the speed signal, for generating a desired torque signal which is a function of both the desired parameter signal and the speed signal;
• means for comparing the desired torque signal to the motor torque signal thereby to supply a comparison signal;
• and
• means for applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the fluid pump is driven by varying the motor torque according to motor speed to maintain the value of the parameter at substantially the desired value substantially independent of variations in the operating conditions of the contained space.

Method for controlling an air handling system including a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a fluid pump in a fluid handling system, the system further including means for generating a desired system parameter signal which varies as a function of a desired value for the parameter, the method providing control of the fluid pump over variations in the operating conditions of the fluid handling system to maintain the parameter at substantially the desired value, the method comprising the steps of:

• sensing the torque of the motor;
• sensing the speed of the motor;
• determining, by use of a microprocessor which is responsive to both the desired system parameter signal and the sensed motor speed, a desired torque which is a function of both the desired system parameter signal and the sensed motor speed;
• comparing the desired torque to the sensed motor torque;
• applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison;
• and
• commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the fluid pump is driven by varying the motor torque according to the motor speed to maintain the value of the parameter at substantially the desired value substantially independent of variations in the operating conditions of the fluid handling system.

Apparatus for controlling an air handling system including a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a blower in the air handling system, the system further including means for generating a desired air flow rate signal which varies as a function of a desired rate of air flow and means for generating a motor current signal representative of the motor current, the apparatus providing control of the blower speed over a range of static pressure variations to maintain the rate of air flow in the system at substantially the desired air flow rate, the apparatus comprising:

• means for providing a speed signal representative of the speed of the motor;
• a microprocessor, responsive to both the desired air flow rate signal and the speed signal, for generating a desired current signal which is a function of both the desired air flow rate signal and the speed signal;
• means for comparing the desired current signal to the motor current signal and for supplying a comparison signal in response to the comparison;
• and
• means for applying a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly whereby the blower is driven to maintain air flow in the system at substantially the desired rate of air flow substantially independent of variations in the static pressure.