About Brushless DC Motor (BLDC) | New Topic [2024]

In this note, we will learn about the Brushless DC Motor or BLDC Motor. Also about the Construction of BLDC Motor, Working Principle of BLDC Motor, and Characteristics as well. Welcome to Poly Notes Hub, a leading destination for Engineering Notes.

Author Name: Arun Paul.

What is Brushless DC Motor?

An electric motor that runs on direct current (DC) and rotates by means of a permanent magnet rotor and many coils is known as a brushless DC (BLDC) motor. BLDC motors have less wear and friction than conventional brushed DC motors since they do not require brushes for commutation. Rather, they rely on electronic commutation, which is often accomplished by a controller or a group of sensors that sense the position of the rotor and adjust the coils’ current flow correspondingly. Because of their economy, dependability, and precise control, BLDC motors are well-suited for a variety of applications, such as robotics, industrial machines, appliances, and automotive systems.

Construction of BLDC Motor

construction of bldc motor or brushless dc motor - poly notes hub

Below we describe the construction of Brushless DC Motors –

  • Rotor: A BLDC motor’s rotor is usually made of permanent magnets organized in a disc- or cylindrical-shaped pattern. Rotational motion is produced by the interaction between the magnetic field generated by these magnets and the stator.
  • Stator: The motor’s stationary component, the stator, is made up of many coils coiled around a core. When activated with an electric current, these coils are usually stacked in a three-phase configuration to create a rotating magnetic field.
  • Encoder: In order to determine the position of the rotor, BLDC motors frequently use sensors like encoders or Hall effect sensors. The motor controller can precisely manage the motor’s speed and direction thanks to the feedback these sensors give it.
  • Motor Controller: The motor controller is an electrical circuit that uses information from the position sensors to regulate the stator coils’ energization. For smooth and effective functioning, the current flow in the coils is normally regulated using pulse-width modulation (PWM) techniques, which also synchronize it with the rotor movement.
  • Bearings and Shaft: Bearings are usually used to support BLDC motors so that the rotor may rotate smoothly. The external load receives the rotational motion from the rotor through a shaft connection.

Working Principle of BLDC Motor

A brushless DC (BLDC) motor runs by using the current flow to create a revolving magnetic field in the stator coils. The rotor rotates as a result of the interaction between this magnetic field and the permanent magnets installed on the rotor. Sensors that track the position of the rotor and give the motor controller feedback include encoders and Hall effect sensors. The controller commutates, or modifies, the timing and amplitude of current pulses to the stator coils based on this feedback. The controller modifies the motor’s rotational speed and direction by precisely adjusting the current flow.

Advantages of BLDC Motor

Below we listed some advantages of Brushless DC Motors –

  1. Efficiency is high because of it brushless construction.
  2. This motor provide high torque in comparison with their size.
  3. These motors can operate in various types of speeds.
  4. Highly reliable and runs continuously with any brake.

Disadvantages of BLDC Motor

Below we listed some disadvantages of Brushless DC Motors –

  1. Very costly motor comparison to other motors.
  2. It generates an EMI effect which interferes with the operations of other devices.
  3. It requires periodic maintenanace.

Applications of BLDC Motor

Below we listed some applications of Brushless DC Motors –

  1. Used in Electric Vehicles like HEVs.
  2. Used in Consumer electronics products and equipments.
  3. Used in Industrial Automation Systems.
  4. Also used in Marine Applications or Engineering.
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