BLDC: The secret of the SuperFan

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BLDC: The secret of the SuperFan

The difference between ordinary fans and superfans is the motor. Motors work on the principle that like magnetic poles repel. The fan blades are attached to a shaft that is connected to the motor. The motor has two main kinds of magnets. A permanent magnet and an electromagnet. The polarity of the electromagnet is changed continuously.  First, the north poles of the 2 magnets repel each other and align with the south poles. Then the electro magnet’s polarity is reversed. So the north poles of the two magnets repel each other again! In an ordinary motor the central core rotor or armature has the electrical windings on it and is the electromagnet. Electricity is conducted to the windings through brushes, since the windings are always turning. These rub against the rotor causing friction and heat losses. So ordinary fans may take about 70W. Super fans use brushless DC motors. Here the electromagnet is the stator and the permanent magnet is the rotor.  The permanent magnet does not need electricity or brushes. The electromagnet is stationary and does not need brushes. The wires are directly connected to the circuit. So these are called brushless motors.  In the absence of friction causing brushes, the heat losses come down by 50%. Superfans need about 35 W only. There are many pairs of alternating poles on the electromagnet used to make the motor turn smoothly.

By | 2017-11-20T16:46:01+00:00 September 29th, 2014|0 Comments

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