What is Brushless Motor? How do Brushless Motor Works

 What is Brushless Motor? How do Brushless Motor Works

What is Brushless Motor? How do Brushless Motor Works

 In this post we will talk about a DC motor which is the ideal choice for many applications where it's needed reliability low maintenance less noise speed control and low cost specifically.

 we are going to see how a brushless DC motor works we can assume already by its name that this type of electric motor has no brushes.

Working principle of DC motors

  we have already seen in our previous post about the working principle of DC motors the brushes are sliding devices which allow the electricity to flow into the copper coil of the engine.

Brushless motors

 brushless motors have no sliding elements on the collector so this completely solves the problem of maintenance and replacement of brushes and other electrical contacts JAES in its catalog offers a wide range of brushless motors of the major manufacturers unlike the common DC mortor.

Functioning of brushless motors

 They use brushes for their functioning brushless motors do not produce sparking or friction noises within them this is a very interesting feature of brushless motors because it allows them to be suitable for use in environments where sparks are dangerous.

What is Brushless Motor? How do Brushless Motor Works

For example 

in environments where ignitable gases are present this type of motor has a rotor with permanent magnetsit could not be otherwise since there are no contacts on the rotor.

Electromagnets of Brushless Motor

 We already said it's stator has electromagnets excited by windings andcoils this is an important difference compared to the traditional brushes DC motor since the latter can have both stator and rotor composed of electromagnets to increase the magnetic fields and therefore have a higher mechanical power density by unit of weight of the motor.


 The torque of the brushless motor is due to the magnetic interaction imposed by the electromagnets on the permanent magnets there is a precise sequence of the electromagnets which imposes to the permanent magnets in angular movement which is always in the same direction.

Rotors Continues Rotation

 It is as constantas possible under the same excitation obviously the sequence is cyclical and the rotor continues its rotation until it's powered repeating the sequence from time to time to be more specific the sequence of excitation of the inside the stator. 

 That the magnets of the rotor are attracted to the electromagnets without ever reaching them as the excitation isalways and only of those coils not yet reached.

 when electricity flows into coilone the opposite poles of the rotor and stator are attracted to each other whenthe rotor is getting close to the coil one the electricity flows in the coil to when the rotor is getting close to the coil to the electricity flows in the coil three later in the coil one the electricity will flow again but with opposite polarity.


 Thist process is repeated continuously inside the engineensuring a constant rotation of the rotor an example to better understand this principle is represented by the dog race in which a hair is placed in front of the Greyhounds at such a distance to be seen but never reached in this metaphor the dogs represent the rotor that follows the magnetic flux generated  exactin sequence in the coils .

What is Brushless Motor? How do Brushless Motor Works


The stator in the case of more coils alwaysmultiples of two it makes sense to use a sequence that uses them all to increase the magnetic flux to which the permanent magnets are subjected.

 Turning off only the opposite electromagnets this simple foresight increases the torquet is the power that the motor can supply without substantially modifyingits design criteria the greater.

Number of coils present in Brushless Motor

 The number of coils the smoother is ther of the rotor which will thus have a constant torque but how does ourbrushless motor know the precise movement in which to excite the corrects of electromagnets which will allow continuity.

 The rotary motion for this purpose an electronic controller is typically used thiscontroller has a sensor to detect the exact position of the rotormagnets and thus decide which coil to energize by following the rightexcitation sequence the modern brushless motor sensors use.

Hall Effect

 The HALL EFFECT in this animation can observe the configuration of a standard sensor thisis a simple to pull device that can drive 2 or 4 or 8 or more electromagnets  in the just seen sequence this is instead the representation of a classiccircuit layout with protection diodes the presence of diodes is necessary toprotect the sensor from negative self inductance 

Types of Brushless Motor

In case we need to suddenly block power supply from one of the coils there are basically two families of brushless motors those with an external stator and those with aninternal stator we can summarize.

DC motor brushless motor

 The main strength points of the brushless DC motor brushless motor is noiseless it is reliable and has a very low MTBF parameter which is the predicted elapsed time between its inherent failures itprovides low energy costs does not require any maintenance it can also be used in flammable environments.


 It has more competitive price than traditional brush motors of the same power however the brushless motor has also its limitations  like requires an electronic driver in order to control the righte sequence uses permanent magnets the specific power is generally lower than the conventional motors equipped with stator and rotor finally.


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