Choice of Motor in an Air Cooler – What can save your energy bills ?

Choice of Motor in an Air Cooler – What can save your energy bills ?

 What are the typical components of an Air Cooler ? 
Air coolers generally contain

  • vents
  • cooling pads
  • pumps
  • motors

What role does the motor play ? 
The motors are the most important components of an air cooler.Pumps and motors power the flow of water into the water distribution channels. The fan is also driven by an electric motor with gearbox.The motors are either axial or centrifugal. Some of these motors need yearly lubrication while other motors have sealed bearings that eliminate the need for yearly maintenance. Homeowners who want quiet air coolers will need belt drive motors though direct drive motors have more efficiency and do not break down as often.
What are the available choices currently ? 
Currently, AC motors are being used in air coolers available in markets.
What is a BLDC motor ?
BLDC motor- Brush Less DC motor
The traditional DC motors have brushes. These brushes wear out over time and require maintainance. The chances of sparking between the brushes are also high and its a tough job to prevent that. Thus DC motors are not advisable for appliances which are required for the long-run.

The recent trend is to use BLDC motors which also produce very less sound while operating.
Here’s an easy way to understand the operation of a BLDC motor. Imagine the following

As the donkey moves forward to grab the carrot, the carrot also keeps moving away.This is basically what happens. 
The rotor of a BLDC motor is a permanent magnet.The stator has a coil arrangement, as illustrated; The internal winding of the rotor is illustrated in the Fig.3 (core of the rotor is hidden here). The rotor has 3 coils, named A, B and C.

The operation of a BLDC is based on the simple force interaction between the permanent magnet and the electromagnet. In this condition, when the coil A is energized, the opposite poles of the rotor and stator are attracted to each other (The attractive force is shown in green arrow). As a result the rotor poles move near to the energized stator.

Fig.1 The rotor moves towards the energized coil, due to the attractive force
As the rotor nears coil A, coil B is energized. As the rotor nears coil B, coil C is energized. After that, coil A is energized with the opposite polarity (compare the last part of Fig.2 with Fig.1).

Fig.2 In a BLDC, as the rotor nears the energized coil, the next coils is energized; this will make the rotor continuously rotate
This process is repeated, and the rotor continues to rotate.
Now lets go back to the donkey-carrot analogy. Imagine the donkey to be the rotor and the carrot to be the stator magnetic flux. Makes sense right?
For a more detailed description, more pictures and a cool video, visit http://www.learnengineering.org/2014/10/Brushless-DC-motor.html
What are the advantages for the user by choosing this motor ? 

  • more reliable
  • requires lesser maintainence and there are lesser parts that can wear out
  • more efficient
  • more life time
  • operates without much noise
  • operates at high speed in both loaded and unloaded conditions
  • safer,spark free
  • cleaner, no dust residues
  • produces less heat
  • smaller and light weight
  • energy saving

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