Room Ventilation Control by a Self-Sensing Fan

This paper describes a scheme for room ventilation control using a self-sensing actuator in a time-sharing manner. Electromagnetic motors and piezoelectric actuators contain internal feedback. Electromagnetic motor's function as electromagnetic generators and piezoelectric actuators generate a voltage when a force is applied to them. These characteristics are referred to as reversibility. We consider the automatic control of an air ventilation system for an airtight house. We found that an aeration fan functioned as a fine-gauge pressure sensor. When there is a pressure difference between the inside and the outside of the room owing to exhaust, the unused aeration fan rotates as a windmill and an induction motor generates a voltage. The control scheme is as follows. When the voltage from the aeration fan, which is at a standstill, exceeds a threshold value, the aeration fan begins to rotate as a fan for a certain period and then returns to the standstill mode to monitor the pressure. These operations are continued in turn. An aeration fan with a diameter of 0.1 m acts as a gauge pressure sensor at pressures exceeding 2.5 Pa with linearity and a cut-off frequency 0.1 Hz. The controller, which turns the aeration fan ON when the pressure exceeds 3 Pa for 10 s and returns it to the standstill mode, worked well in an actual airtight room.