The benefits of synchronous brushless DC motors

17 February 2019

In this article, we will show the main benefits of synchronous brushless DC motors, also known as BLDC (BrushLess Direct Current) motors, powered by inverters and having permanent magnet rotors.

BLDC motors are composed of three main elements:

  • the stator, which consists of a pack of stamped T-shaped laminations or sectors (assembled to form the stator); coils are wound on the teeth of these laminations to form the windings, which are connected to each other and to the electronic board
  • the rotor, which consists of a cylindrical support with permanent magnets glued to it, or a pack of stamped laminations with ‘pockets’ in them to hold the permanent magnets
  • the electronic board that functions as a controller to ensure that the motor works correctly

Since the ’80s, the development of semiconductors has paved the way for the introduction of these motors. A considerable reduction in electronic component sizes in recent years has led to an increase in their growth, and they now replace brushed DC motors in some applications, thanks to some significant benefits:

  • replacing the brushes and commutator with a PM rotor and electronic board offers greater and better dynamic performance (meaning the range of available speed and torque, and fine adjustment)
  • no maintenance problems due to brush wear
  • no sparks in the sliding contacts, which are dangerous in potentially explosive atmospheres
  • less noise, both acoustic and electromagnetic
  • increased efficiency (because there is no friction and power dissipated in the contacts between the brushes and commutator)
  • increased power/weight ratio
  • smaller overall motor size for the same performance

They are also widely applied in very high-efficiency AC motors, where the traditional asynchronous motor is unable to achieve the required low-consumption performance.

Given these benefits, it is also worth mentioning at least two significant drawbacks that partly limit the success of these motors:

  • the cost of permanent magnets, especially for high-quality magnets such as neodymium
  • the cost of the electronics, especially if the quantities do not justify large-scale economy

That said, these motors have undergone an explosive growth in recent years, to the point that they are used in various sectors, and companies are showing an increasing interest in this world. Here below, we provide a non-exhaustive list of the main applications of BLDC motors:

  • pumps and ventilation
  • household appliances
  • gate openers and automation in general
  • home automation
  • electric bicycles (E-bikes)
  • hub motors for scooters
  • automotive
  • generators and alternators

Came has not been caught unprepared for this scenario, having gained solid experience in prototyping, industrialising and manufacturing the wound stator, with a fleet of machines in two manufacturing centres, which we will expand over the coming years with a further three centres to effectively meet the needs of our customers.

Article by:
Fabrizio Bardelli
Came Expert in Research and Development
+39 0444 488282