Small Brushless Motors For Compact Applications And Accurate Performance
Small brushless motors are compact motion control devices that are used in many different applications. These electric motors offer many advantages, including excellent efficiency, low-temperature operation, reduced weight and heat, and a consistent, virtually maintenance-free performance.
Small brushless motors are powered by direct current. They are characterized as synchronous motors, which means there is synchronicity between the rotation of the motor’s shaft and the frequency of the supply current.
Brushless DC motors are sometimes called BLDC motors or electronic control (EC) motors. One of their main characteristics is the use of an electronic servo system that feeds power to the stator and drives the motor’s phases via a sliding current. This type of motor is an advancement over brush-style motors, which were a common DC motor prior to the development and adoption of solid-state electronics.
In a brush DC motor, a sliding current is introduced to the stator through a mechanical carbon brush. This part functions as the motor’s commutator. The sliding current then creates a field from the electromagnets of the stator. This field resists the field of the permanent magnets of the rotor, which causes rotational motion and is used to drive all types of equipment.
This arrangement will reliably convert electrical energy into mechanical power or torque. When a carbon brush commutator is used to facilitate this process, there are some inherent limitations and weaknesses that must be taken into account.
Since brush motors use a mechanical component to create a sliding current, there is some degree of friction and heat. There is also a potential for sparking, which can restrict the use of brushless motors where there is a strong risk for fire-hazards.
Brush motors can create a lot of noise during operation and will typically weigh more than motors without a carbon brush. Such a component will inevitably wear down over time and require replacement. Such maintenance demands are to be expected with all brush-style motors.
Brush motors are still in use today, although they are typically reserved for low-power, non-critical propulsion purposes that do not require a long-duty operation. They have otherwise been phased-out in favor of DC brushless motors.
Through the innovation of an electronic servo system, which eliminates the need for a mechanical commutator, DC motors have been improved on many fronts. Brushless motors run quieter, cooler, demand less electricity to produce more power, do not spark, and can be made much smaller or larger than brush motors without excessive weight or heat generation.
Brushless motors also last much longer. As there is no carbon brush to wear down with operation, they are virtually maintenance-free. When properly suited to the requirements of an application, they offer consistent and reliable performance. Their operational life is only limited to the motor’s bearings.
Because of these and other advantages, it’s possible to make brushless motors to very compact sizes. Small brushless motors can be scaled down to serve as motion control and continuous power components in all types of scaled-down and micro applications.
Small brushless motors serve as the power source in many handheld and cordless tools. This includes drills and screwdrivers, saws, various rotary tools, hairdryers, personal fans, trimmers, dentist drills, various medical and surgical devices, and many other types of electronically-operated equipment.
Smooth, high-efficiency performance, that also offers reduced heat and friction, is favorable for motorized tools that are meant to be hand driven. Small brushless DC motors also pair well with equipment meant to be plugged into an AC outlet or adaptor or that is meant to be rechargeable.
Small brushless motors are used for many continuous power, long duty-cycle applications. Computer hard drives and cooling fans, audio turntables, and similar equipment all use compact brushless DC motors as a power mechanism. Since these motors are lightweight and quiet, they are well suited to such placements.
Apart from continuous motion applications, small brushless motors can easily accommodate the requirements of positioning and actuation systems. These are applications that require motors to stop and start with speed and accuracy, which is integral to the modulation of remotely-controlled, moving parts. Robots, RC equipment, and automated manufacturing and assembly tools are just a few examples of brushless motors in motion control applications.
Small brushless DC motors used in such capacities will require the addition of positional sensors and special motor controllers. Also called sensored brushless motors, these devices use feedback sensors to automatically identify the position of the rotor on start-up. This leads to a quick and accurate initiation of power.
Sensored brushless motors can be started and stopped with rapid and reliable accuracy. Their performance is similar to servo and stepper motors used in many robotics and actuation systems. These motors are best suited to applications that do not require long duty cycles and where only moderate speed is needed.
Since brushless motors, in general, offer extended longevity and require virtually no maintenance, they are suitable for critical settings as well as non-critical capacities. With a high-performance design and components, small brushless motors can be reliably integrated into military, aerospace, heavy-duty industrial, and medical equipment.
In settings where moisture, exposure to particles and debris, or temperature fluctuations or extremes may be likely to occur, it’s very important that the motor be properly insulated to prevent such factors from compromising performance. Extended endurance improvements can be gained through the addition of potted coils, vacuum impregnation, and special stator winding assemblies.
Depending on the application, small brushless motors can be sourced as direct drop-in components that are ready for incorporation into standard systems. These motors can be acquired from electronic parts suppliers and larger manufacturers.
When a motor must be designed, modified, or customized to suit the requirements of original equipment, or to improve upon the performance limits of standard devices, independent motor manufacturers can extend such services. Companies that offer built-to-print capabilities and custom engineering and production services will be best able to serve the needs of original equipment manufacturers and independent buyers.