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    All the Differences Between Brushed and Brushless Motors

    2022-06-16 09:10:13 350

    One of the most fundamental machine inventions of the last 200 years is the DC motor. This electric motor generates rotational motion using direct current (DC). It has made it possible for designers to build powerful tools and mobile equipment, and other important applications powered by batteries.

    DC motors are categorized into two types: brushed DC motors and brushless DC motors. While they have many similarities, they differ in other ways. We already know that one has brushes and the other doesn’t but their differences go beyond that. But before we go further, let’s explore a bit more about brushed and brushless motors.


    What is a Brushed Motor?

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    A brushed DC motor uses what is called the “armature”, which has wound wire coils that act as a two-pole electromagnet. Twice in every cycle, a mechanical rotary switch - the commutator - reverses the directionality of the current. 

    The poles of the electromagnet pull and push against the permanent magnets along the outside of the motor. The armature’s electromagnet polarity is reversed by the commutator as its poles cross the permanent magnets’ poles to form a direct current.

    The first commercially important motors made were brushed motors. They have been used in operating motors in commercial and industrial applications for more than 100 years. 

    Brushed motors are the most basic type. They can be varied in speed by changing the operating voltage or the strength of the magnetic field in them. Many applications make use of this level of control. There are four basic components in brushed motors:

    • Brushes

    • The stator 

    • The rotor, or armature

    • The commutator


    What are Brushed Motors Used For?

    You can find brushed motors everywhere in the home and when out and about. Whenever there is the need to convert electricity into rotational motion, you are likely to find a brushed DC motor around.

    Whether it’s a toy or any other electric device that moves, it is likely to have one. This amazing engineering technology is used by anything from electric toothbrushes to motorized bread slicers.

    In larger uses, DC brushed motors are found in machines (like cranes, drills, electric propulsion systems, and steel rolling mills, to name but a few) because of their ability to change the torque to speed ratio, which is found exclusively in brushed motors.


    What is a Brushless Motor?

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    On the other hand, a brushless motor doesn’t need brush electrodes to turn the rotor. Brushless motors do not require a physical commutator. They are widely known to have a higher power-to-weight ratio, level of control, speed, and lower need for maintenance compared to brushed motors.

    They partly reverse the brushed motor working principles. For example, permanent magnets are used on the rotor while the rotor is spun by controllable electromagnets. Brushed motors come in two forms:

    • Inrunner: This type has the stator located on the outside of the rotor;

    • Outrunner: This type has the stator located inside the rotor. It is typically found in older floppy disk drives, etc.


    The copper winding coils in a brushless motor are fixed, as it is the permanent magnet that turns along with the rotor. There is a small circuit board that is used to mimic the way brushes work in traditional brushed motors by managing the energy supplied to the electromagnets.

    Besides that, the basic principle of the technology is not that different from a brushed motor, although the application is a bit different. Brushless motors were first used in the 1960s, a time when solid-state electronics were emerging.


    What are Brushless Motors Used For?

    Brushless DC motors, much like the brushed ones, are widely used today in a series of applications. As a result of their high efficiency and controllability as well as longer lifespan, they are typically present in devices that are always running or are used regularly.

    You can find them in appliances like washing machines, electrical fans, air conditioners, and other consumer electronics. Because of how they work, they have significantly reduced the power consumption of major modern electronic devices.

    Brushless motors are used in electric vehicles and drones, as a result of their ability to deliver precision control. This is important as it is essential for drones to constantly and precisely control each rotor speed in performing actions such as hovering.

    They are fast becoming the motor of choice for many electronics being developed today because of their durability and dependability over a long-term, energy efficiency as well as high output power to size ratio.

    It is for this reason that brushed motors will continue to find increasingly new applications.


    The Differences Between Brushed Motors and Brushless Motors

    Having taken a look at brushed and brushless motors and how they work, by now, you should have already gotten some idea of the differences that exist between each of them. But there are more differences that can be mentioned:

    • Brushed motors are not as efficient as a result of the power losses that occur through friction and transfer of power through their commutator system. Brushless motors, on the other hand, are more efficient as a result of the lack of mechanical losses as compared to brushed motors;

    • Due to their design, brushed motors don’t have a long lifespan, as their brushes wear and tear quicker. Their brushes typically need to be replaced every two to seven years. Brushless motors have no brushes and physical commutators, and require less maintenance overall;

    • Brushed motors implement a more complicated method of speed control. While lowering voltage reduces the torque, this comes at a cost of lower speeds as the torque dramatically drops off. As for brushless motors, they are easier to control and this is why they tend to have a higher torque at lower speeds;

    • Brushed motors are not suited for most applications because of their excessively faster speed. They usually require a gearing system to reduce the speed and thus increase torque. However, this is where brushless motors excel the most. This is why they are typically used directly without any need for gearing;

    • Brushless motors run quieter. They are also lighter, more efficient, more durable, and safe for some applications. Brushed motors, on the other hand, generate sparks, which make them unsuitable for places where there is a risk of explosion. For this reason, brushless motors are typically preferred in hazardous working conditions;

    • It should come as no surprise that brushless motors are more expensive given their relative complexity. On the other end, brushed motors are relatively cheap and affordable; 


    Now that you have a full understanding of these two types of electric motors and their design principle, you can now better appreciate the relative pros and cons of either device.

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