Brushless DC Fan Working:

Brushless DC Fan-Energy Efficient and Noiseless:

Fans are an integral part of every individual’s life. A Brushless DC Fan so-called BLDC fan, uses a new technology called Brushless DC technology (BLDC) that has been introduced in fans nowadays.

Traditional ceiling fans run on AC induction motors. But fans with BLDC technology use Brushless DC motors that cut power consumption by 65% and increase the lifespan of the fans.

Let us discuss the following details about BLDC Fans.

• What is a BLDC Motor?
• Construction of a BLDC Fan
• Working of a BLDC Fan
• Advantages of BLDC Fans

What is a Brushless DC Motor?

BLDC stands for BRUSHLESS DIRECT CURRENT MOTOR. In previous days, DC motors had a commutator along with brushes. With the passage of time and new technology, it has become possible to eliminate the brushes from DC motors.

A Brushless Direct Current Motor (BLDC) is an electric motor that is powered by a DC electric source. The motor converts electrical energy into rotational (mechanical) energy.

BLDC motor uses an integrated inverter power supply to provide an electrical signal to drive the motor.

How do BLDC motors differ from conventional DC motors?

• Commutation System:

BLDC motors have an electronically controlled commutation system (instead of the mechanical commutation system using brushes)

• Magnetic System:

Traditional fan motors consist of electromagnets.  BLDC motors contain permanent magnets rather than electromagnets used in induction motors.

 In a BLDC motor, the permanent magnets are put on the rotor that moves around the stator. The permanent magnet contains less heat loss and energy compared to electromagnets.

Construction of a Brushless DC Fan:

Parts of BLDC Motor:

Stator – The stationary object contains Copper windings, which produce magnetic flux when an electric current is passed through them.

Rotor – The rotating object contains permanent magnets.

Shaft – The rod connecting a motor to the application

BLDC Drive– The drive contains control electronics to run the motor in a controlled manner.

Working of a Brushless DC Fan:

The basic construction of a brushless DC fan consists of a fan blade attached to a permanent magnet rotor that surrounds the electromagnetic coils of the stator and associated control electronics.

The heart of the BLDC fan is the BLDC Drive. The working of the BLDC drive is as follows.

BLDC drive consists of the following equipment.

1. SMPS
2. Micro Controller
3. Inverter

1. SMPS: Switched-Mode Power Supply (SMPS)

The main purpose of an SMPS is to provide regulated, stable power to the BLDC drive. A switched-mode power supply circuit is designed to obtain the regulated DC output voltage from an unregulated AC voltage. Here, an SMPS is used to convert AC supply into a DC supply.

2. Microcontroller

A microcontroller is used for receiving the input data from the remote control and giving output data accordingly to an inverter.

3. Inverter

An inverter is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). After receiving a signal from the microcontroller, the inverter provides a supply to run the motor.

Fan blades are attached to a permanent magnet rotor of the motor to provide wind.

Working of Brushless DC Drive:

BLDC fan working principle is that when we turn on the fan, the SMPS converts the AC supply to a DC supply; then, after the microcontroller receives the input signal from the remote control, and accordingly input signal microcontroller sends the signal to the inverter, and then the inverter drives the BLDC Motor.

 A closed-loop Microcontroller receives power from the BLDC via an inverter, as shown in the figure below.

When the stator coils get a supply from the source, they become electromagnets and start producing a uniform field in the air gap. Though the source of supply is DC, using inverter switching generates an AC voltage waveform with a trapezoidal shape.

Due to the force of interaction between the Electromagnet stator and Permanent magnet rotor, the rotor continues to rotate. With the switching of windings as High and Low signals, the corresponding winding is energized as North and South poles. When two same polarities (Ex S & S, N & N) take place on the rotor and stator, magnetic force pushes the rotor to rotational movement.

So, for continuous rotation in the rotor, the polarity in the stator changes continuously, so every time the same polarity takes place on the rotor and stator, it helps with continuous rotation in the rotor. The permanent magnet rotor with North and South poles aligns with the stator poles, which causes the motor to rotate.

Advantages of Brushless DC Fans:

A brushless direct-current (BLDC) motor is an advanced electric motor with an electronic commutator system. Prominent advantages of BLDC motor fans over induction motor fans are

• BLDC motor fans do not run via regulators because of their distinct electrical design. They operate on a remote control. Accurate Speed control, with the help of the remote control, can set the speed, timer, and even sleep. This feature makes it convenient to use.

• BLDC motor fans consume low power, making them inverter-friendly and cost-saving machines. 

• BLDC fans use less power than an induction motor fan. BLDC fans consume around 35 Watts, unlike an ordinary fan that consumes about 80 Watts. That proves them to be energy-efficient fans.

• Although the cost of BLDC fans is high compared to ordinary fans, a BLDC fan is a money saver for customers, as it saves up to Rupees 1000-1500 per year.
• BLDC motor has a longer lifespan as they do not get heated because the magnetic fields are around the fan, not in the center of the fan. A standard fan gets overheated.

• BLDC fans are silent compared to a standard fan due to the absence of brushes on the rotor, and the commutation is performed electronically.