Advantages and disadvantages of brushless dc motor

Electrical Motor is a device, which converts electric energy into mechanical energy in the form of a revolution of some shaft known as the rotor.

Most of the electric motors operate on the principle that when a conductor is been placed in a magnetic field and current flows through it. This will result in a force exerted on the conductor, and the direction of the force can be identified by the filming’s left-hand rule.

There are multiple types of DC motors; however, two common types of DC motors are brushless DC motor and Brushed DC motor.

In brushed DC motor, a conducting material called rotor is placed between the permanent magnets known as the stator. When current flows through the armature winding, force is exerted on the rotor which rotates the rotor in the direction according to left-hand rule. This causes the rotor to rotate 180 degrees. To further rotate the rotor to 360 degrees, the direction of current is reversed by the help of commutators and brushes. This results in a complete revolution of 360 degrees, and the motor keeps on rotating and the current direction also keeps on reversing after each half revolution.

On the other hand, in the case of brushless DC motor, the rotor is a permanent magnet while the stator is an electromagnet. Unlike in brushed DC motor, carbon brushes are not used for the reversal of the direction of the current for complete 360-degree rotation, but the current is controlled through some electronic controller. This not only provides a solution for the issue of frequent Maintainance due to the damage of carbon brushes requiring replacement, but it also provides high-resolution speed control and accuracy.

Now we talk about “Advantages and disadvantages of brushless DC motor”,

Advantages of Brushless DC motor

Brushless DC motors have many advantages our the traditional brushed DC motors. Few of the advantages are discussed below in detail:

  • Brushless DC motor does not have any carbon brushes, which reduces frequent replacement requirements of brushes and maintenance costs.
  • Brushless DC motors have better performance and efficiency as compared to the brushed DC motors due to the involvement of electronic control enabling high-level control over the speed and position of the motor. Brushless DC motor lifespan is approximately 6 times higher than the counter brushed DC motor.
  • Brushes can cause high sparks which may result in short life or complete burnout of brushed DC motor. However, in the case of brushless DC motor, due to no spark issue, there are fewer chances of burnout due to sparking issues.
  • Brushless DC motors are available in small compact sizes and also provide high torque to weight ratio making it suitable for many robotics and medical applications involving robotic arms and robotic legs.
  • Brushless DC motor produces comparatively low operating noise as compared to other motors of the same ratings. As in other motors, there is continuous contact of brushes resulting in noise and sparking during contact. Therefore, brushless DC motors are given preference where electrical noise needs to be avoided.
  • As traditional commutation based on mechanical setup is replaced by the modern electronic commutation system resulting in more control and fewer chances of failure due to previously discussed reasons of wear and tear.
  • Unlike other motors, brushless DC motor has low no-load current making it suitable to run it at low or no load.
  • Brushless DC motors can provide maximum torque continuously during rotation, while brushed DC motor can provide maximum torque at an only specific point of the rotation. For the same torque rating, the brushed motor will require a much bigger magnet as compared to the brushless DC motor. This results in a very compact and small-sized brushless DC motor proving very high torque rating.
  • Brushless DC motors can have a feedback control to monitor and control the speed and torque, resulting in accurate torque and speed control providing higher efficiency, low power consumption, and long battery life in the case where the motor is operating using some batteries.
  • Brushed DC motors have the heating issue and do not cool quickly due to the presence of electromagnet in the center of the motor. On the other hand, the brushless DC motor does not have an electromagnet in the center reducing the heating issue.

Disadvantages of Brushless DC motor

Just like in all the other devices, brushless DC motors also have few shortcomings as compared to other motors. As brushless DC motor outperforms brushed DC motor in many cases, however, brushless DC motor also has few shortcomings which are discussed below:

  • The cost of a brushless DC motor is comparatively higher as compared to brushed DC motor and the electronic controller also increases the cost of overall setup, as in a traditional motor, low-cost mechanical commutation setup involving brushes is used.
  • When brushless DC 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 brushless DC 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 resonance phenomenon in many brushless DC motor based devices.
  • Brushed DC motors are easy to operate having simple wiring as the positive terminal is connected to positive and negative terminal is connected to negative wire and motor starts to rotate. However, in the case of brushless DC motor, wiring and operation of the motor are not that simple due to the involvement of electronic control and its link to all the electromagnets.

In short, brushless DC motor has many advantages our the traditional brushed DC motors such as low maintenance cost and less frequent maintenance requirement. They are also compact in size and provides high torque with better speed control and efficiency. On the other hand, it also has a few disadvantages like higher cost, resonance issue, and complex wiring setup due to the involvement of electronic control. So I think you can understand the advantages and disadvantages of brushless DC motor,

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