Design and implementation of constant air volume control system for fan motors based on sensorless

The output air volume of a fan motor will be different and not a constant value all the time when the fan motor works. There are mainly two aspect reasons. On one hand, for one given fan motor, the pipeline resistance will change because of the clogging of the filter and other reasons. On the other hand, for different fan motors, the motor efficiencies are not the same. The paper presents a constant air flow control method without using air volume sensor. The method can adjust the air-blower speed automatically to keep a constant air volume by measuring the fan motors parameters under different working conditions in real time. The single-chip XC866 is used as the core of the control system, which controls the output air volume automatically by detecting signals of voltage, current and rotor position. The result proves that a constant output air volume can be achieved under different expected air volume values for fan motors by using the method based on sensorless and it also has a high precision.