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Difference between Brushed Motors and Brushless Motors
An electrical machine that is used for the conversion of electrical energy into mechanical energy is known as electric motor. Based on the type of electric supply input, the electric motors are of two types − AC motor and DC motor. An AC motor is the one which takes alternating current supply as input and converts it into mechanical energy while the DC motors takes DC supply as input.
Present day advancements in the motor technology allows the use of DC motors in several applications from small toys to larger industrial machinery. DC motors come in two variants viz. Brushed DC Motor and Brushless DC Motor.
In this article, we will list all significant differences between brushed and brushless DC motors. But, before discussing the differences, it is advantageous to know about the basics and working of these two motors.
What is a Brushed DC Motor?
Brushed DC motor is a type of DC motor which uses the carbon brush mechanism for supplying the electrical power to its armature circuit. The brushed motor is mechanically commutated DC motor.
A brushed DC motor consists of two parts − armature (rotor) and magnetic field system (stator). Since, the armature winding is placed on the rotor, therefore a mechanism is necessary for providing the electric input to the rotating armature. This mechanism is provided by the help of commutator and carbon brushes.
In a brushed DC motor, the commutator is a split ring which is mounted on the rotor shaft and provides the internal commutation and the carbon brushes are made to slide over the commutator surface. The DC electric input is connected to the carbon brushes, which is further supplied to the armature winding through the commutator. Therefore, by the interaction of electric current in the armature winding and the magnetic field of stator, an electromagnetic torque is produced in the rotor which rotates it to drive the mechanical load.
What is a Brushless DC Motor?
Brushless DC motors or BLDC motors is a type of DC motor which does not use carbon brush mechanism for supplying the electric power to it.
Since the BLDC motor does not use brushes, therefore, the electric power is supplied to the stator of the motor. The rotor of the brushless DC motor consists of permanent magnet. In the BLDC motor, the DC supply is connected to the stator winding to produce a magnetic field which pulls or pushes the rotor’s magnetic field to rotate it.
In a brushless DC motor, the stator winding is made of multiple windings that surrounds the rotor and a hall-effect sensor is employed for the detection of position of the rotor and switches the electrical input to the correct stator winding. As the switching of stator winding is required in the BLCD motor, thus these motors use electronic commutation instead of mechanical commutation (commutator and carbon brush mechanism), for this purpose a switching device such as SCR is used and the controlling of the switching device is provided by using a microcontroller.
Difference between Brushed Motor and Brushless Motor
Both brushed and brushless motors are types of DC motors. However, there are several differences between brushed motor and brushless motor, which are enlisted in the following table −
Basis of Difference | Brushed Motor | Brushless Motor |
|---|---|---|
Definition | A type of DC motor which needs carbon brushed for supplying the electrical power to the armature winding of the motor is known as brushed DC motor or simply brushed motor. | Brushless motor is the type of DC motor in which carbon brushes are not required for supplying the input electrical power. |
Major parts | The major parts of a typical brushed DC motor are: stator, rotor, commutator, carbon brushes. | The major parts of a brushless DC motor are: stator, rotor, hall effect sensor. |
Input | In a brushed DC motor, the DC electric power is input to the rotor. | The DC input power is given to the stator of the brushless DC motor. |
Stator | The stator of the brushed DC motor contains the magnetic field system in the motor. | The stator of the brushless DC motor contains the armature windings of the motor. |
Rotor | The rotor of the brushed DC motor contains the armature winding. | The rotor of the brushless motor forms the magnetic field system. |
Commutation | The mechanical commutation is provided in the brushed DC motor through the assembly of commutator and brushes. | The electronic commutation is employed in the brushless DC motor through the solid state switches. |
Speed range | Brushed motor has lower speed range due to the mechanical limitations because of the presence of mechanical commutator and brushes. | The speed range of brushless DC motor is high because of the absence of mechanical limitations due to commutator and brushes. |
Electrical noise | In brushed DC motors, the electrical noise is more due to arc between the brushes and commutator. | There is no electrical noise present in case of brushless DC motor. |
Lifespan | Brushed motors have shorter lifespan due to wear and tear of commutator and brushes. | Brushless motors have very long lifespan. |
Maintenance | Brushed motors need frequent maintenance due to the wear and tear of carbon brushes and commutator. | There is no commutator and brushes in a brushless motor, hence less maintenance is required. |
Speed-torque characteristics | The speed-torque characteristics of a brushed motor is moderately flat and linear, it is because at high speeds, the brush friction increases which reduces the useful torque. | Brushless motor has flat and linear speed-torque characteristics which enables it to operate at various high ranges of speed. |
Safety | In a brushed motor, a spark can be generated at the contact of commutator and brushes, which is not ideal in places where there is a risk of explosion. | There is no spark is produced in the brushless motor, they are preferred choice in hazardous working conditions. |
Speed control | Brushed motors use simple and inexpensive speed control methods. | The speed control methods of brushless motors are complex and expensive. |
Efficiency | Due to the power loss through friction and power transfer through the commutation system, the brushed motors are less efficient. | Brushless motors are highly efficient due to the absence of mechanical losses in commutator system. |
Physicalsize
(for same rating) | Brushed motors are relatively larger in size. | The physical size of brushless motors is relatively smaller. |
Design complexity | Brushed motor has simple design. | Brushless motor has complicated design due to multiple stator windings and sensors. |
Need of controller | In a brushed motor, for a constant speed, there is no need of controller. If variable speed is required, then only a controller is needed. | In case of brushless motor, a controller is necessarily required for the normal as well as variable speed operation of the motor. |
Overall cost | The overall cost of a brushed motor is less than that of the brushless motor. | Brushless motor is more expensive than brushed motor. |
Application | Brushed DC motors are extensively used in various electronic appliances, toys, industrial machineries, medical equipment, power tools, robot, etc. | Brushless DC motors find applications in electric vehicles, industrial equipment, electric bicycles, fans, pumps, washing machines, blowers and drones, etc. |
Conclusion
The major difference between brushed DC motor and brushless DC motor is that the brushed motor uses mechanical commutator and carbon brushes for performing the commutation, whereas the brushless motor uses electronic commutation and the carbon brushes are not used in this motor. The above comparison shows that a brushless DC motor is better than a brushed DC motor in terms efficiency, electrical noise, physical size, speed range, safety, etc.
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