System and method for determining a condition of a fluid flow path

A method for determining a condition of a fluid flow path, said method is implemented by a motor controller that is configured to be coupled to a motor that is coupled to a backward-curved fan, the motor controller includes a processor coupled to a memory, said method comprising:

• operating, by the motor controller, the motor to rotate the backward-curved fan at a first speed in a forward direction that causes a fluid to move from an inlet of a fluid flow path to an outlet of the fluid flow path, wherein the backward-curved fan is curved backward with respect to a direction of movement of the fluid through the fluid flow path, and wherein restriction of the fluid flow path does not increase a torque associated with the motor while operating in the forward direction;
• storing, by the motor controller, a schedule for a restriction detection mode in the memory, the schedule defining times when the motor is to be operated in the restriction detection mode;
• operating, by the motor controller, in accordance with the schedule, the motor to rotate the backward-curved fan in a reverse direction that is opposite the forward directions wherein restriction of the fluid flow path increases the torque associated with the motor while operating in the reverse direction;
• determining, by the motor controller, the torque associated with the motor while the motor is rotating the backward-curved fan only in the reverse direction during the restriction detection mode;
• determining, by the motor controller, that the torque is not within a predefined threshold range stored in the memory, the predefined threshold range indicating an expected range of torque for resulting from the backward-curved fan to operate operating in the reverse direction when no restriction or an acceptable restriction is present in the fluid flow path;
• and determining, by the motor controller, that a an unacceptable restriction exists in a fluid flow path in response to determining that the torque is not within the predefined threshold range.

A non-transitory computer-readable storage medium having processor-executable instructions stored thereon, wherein when executed by a motor controller that is configured to be coupled to a motor and is coupled to a backward-curved fan, wherein the motor controller includes a processor coupled to a memory, said instructions cause the motor controller to:

• operate the motor to rotate the backward-curved fan at a first speed in a forward direction that causes a fluid to move from an inlet of a fluid flow path to an outlet of the fluid flow path,
• wherein the backward-curved fan is curved backward with respect to a direction of movement of the fluid through the fluid flow path, and wherein restriction of the fluid flow path does not increase a torque associated with the motor while operating in the forward direction;
• store a schedule for a restriction detection mode in the memory, the schedule defining times when the motor is to be operated in the restriction detection mode;
• operate, in accordance with the schedule, the motor to rotate the backward-curved fan at a second speed in a reverse direction opposite the forward direction, wherein restriction of the fluid flow path increases the torque associated with the motor while operating in the reverse direction;
• determine the torque associated with the motor while the motor is rotating the backward-curved fan at the second speed only in the reverse direction during the restriction detection mode;
• determine that the torque is not within a predefined threshold range stored in the memory, the predefined threshold range indicating an expected range of torque for resulting from the backward-curved fan to operate operating in the reverse direction when no restriction is present in the fluid flow path;
• and
• determine that a restriction exists in the fluid flow path in response to determining that the torque is not within the predefined threshold range.