BLDC Motor vs. Induction Motors in Ceiling Fans

Energy Saving is the new mantra in all electrical products and its importance has hugely become important in past few years on a national as well as international scene. Ceiling fans being widely used in tropical areas like India rank very high in energy guzzling. Brushless DC Motors or BLDC motors as they are called are gaining huge momentum in modern, high-efficiency appliances such as air conditioners, compressors, and water pumps and in domestic appliances. So, Ceiling fans can’t be left behind. With the BEE Star rating programme for Ceiling fans becoming mandatory in few months , the focus on replacing traditional Induction Motor with BLDC motors is but given.

The global BLDC motor market is segmented on the basis of type, end-user, and geography. Based on the type, the market is divided between inner rotor and outer rotor. Based on end-user, the market is divided across industrial machinery, motor vehicles, HVAC equipment, aerospace & transportation, household appliances, healthcare, and others.

Presently, over 95% of Ceiling Fans manufactured in India are having Capacitor type Single phase Induction motors. These have wound stators with main and auxiliary windings and have Aluminium Die cast Rotors which are sandwiched between the top and bottom covers on which blades are mounted to rotate and give breeze. Speed Control is done by voltage control in these motors.

BLDC motors for Ceiling Fans are also constructed with Electrical windings on the stator but have  permanent magnets as the rotor. The power requirement of BLDC motors is less as compared with induction motor. Speed control is by controlling the switching frequency of BLDC Motor. Simply stated, the circuit consists of ac supply, rectified to low dc voltage, inverted to variable frequency ac to stator. Stator Windings are also different as main and Aux windings are replaced with three phase or single phase winding as per the motor design.

In Induction Motor ,the Capacitor creates phase difference to give continuous rotation field.  IN BLDC motor ,this responsibility  is of Electronic Controller  with switching between the phases as per program written in the IC Controllers.

Let’s understand the construction difference.

What are its advantages and disadvantages?
Advantages

• 60% less power consumption due to flux of permanent magnet.
• BLDC motors have better performance and efficiency due to the involvement of electronic control enabling high-level control over the speed and position of the magnetic rotor.
• BLDC motors can be housed in small compact sizes. So new designs and aesthetics are possible.
• BLDC motors produce comparatively low operating noise as compared to induction motors of the same ratings. Induction motors do generate some electrical humming while in normal operation & high load condition.
• Electronics make these fans compatible for Remote speed regulating, lot functioning, Wi-Fi enabled control & many more futuristic applications of smart products.

Disadvantages

• The cost of a BLDC ceiling fan is presently substantially higher as compared to an Induction ceiling fan and the electronic controller also increases the cost of overall machine.
• When a BLDC motor is operated at low speed, slight vibrations occur during low-speed rotation. However, vibrations reduce at high speed.
• Due to the inherent natural vibration frequency of BLDC motor, sometimes this natural frequency can match or can come closer to the vibration frequency of the body or plastic parts resulting in the occurrence of resonance phenomenon. However, this resonance can be minimized by adjustment, and it is common to observe the resonance phenomenon in many brushless DC motor-based devices.
• In BLDC motors, wiring and operation of the motor are not that simple due to the involvement of electronic control and its link to all the electromagnets.
• Robustness of Electronic control system has not yet surpassed the reliability of Induction motor Ceiling fans. Failure occurs due to variations in Input Supply.
• The after sales service would have huge teething issues till the technicians all over country get fully familiarised with the nuances of electronics.
• The supply chain for Magnets and Electronics is presently a huge challenge—So perhaps the changeover planned should not be rushed.

In conclusion , a great new era with this new technology awaits Indian Fan Industry and the Fan users—Costly fans for sure but huge savings in power bills –for sure.
So let’s welcome the changeover.