Small BLDC Motors
Small BLDC motors are ideal for applications that require high reliability and low maintenance. They offer superior performance, including fast response to operational changes.
Unlike brushed DC motors that use brushes and a mechanical commutator, BLDC motors lack a mechanical commutator. They must be powered using an electronic commutator. This requires sequential switching of power electronic keys strictly dependent on the position of the rotor shaft.
Power
For a motor to produce torque, current must be applied to the stator coils and then to the permanent magnets. The direction and timing of this current must be precisely controlled. This is done through a process called field-oriented control. This method energizes each phase (U, V, and W) in a pattern that matches the motor’s winding currents. This allows the rotor to chase the magnetic flux and maintain rotation.
BLDC motors are widely used today in drone systems, where they can provide high speeds and torque with low noise and heat. They’re also used in appliances like washing machines and dryers, and for spinning optical/magnetic media in CD/DVD/Blu-ray players.
Compared to other types of motors, BLDC motors have a much higher torque density in a smaller frame. They’re also quieter and more energy efficient. This means they can power more equipment and extend battery life without compromising performance. Moreover, they offer longevity and low maintenance with no brushes to wear out over time. This makes them an ideal solution for many applications.
Efficiency
Small BLDC motors are renowned for their efficiency and longevity. They can operate continuously for longer than conventional brushed motors without any significant heat generation, which reduces power consumption and prolongs battery life. They also offer superlative controllability, which makes them ideal for running devices such as fans and electrical pumps. They’re even used to spin hard disk drives, where their durability and efficiency improves the operation of the drive over the long term and helps achieve greater energy reduction.
Unlike brushes, which wear down and must be periodically replaced, BLDC motors have permanent magnets and fixed coils. To control rotation, the current supplied to these coils is controlled via external electronics instead of relying on sliding contacts and a commutator. This eliminates the friction and abrasion that causes the unavoidable wearing down of the motor components.
Since BLDC motors are more efficient than their brushed DC counterparts, they can operate at lower speeds while delivering the same amount of Small BLDC motor torque. This translates into higher efficiency and more power per kilogram for mobile applications.
Torque
The torque of a Small BLDC motor is the amount of force it produces, and is determined by the voltage and current being applied to the motor. The higher the voltage, the more torque. A BLDC motor is capable of producing more torque than its brushed DC counterparts, and can be precisely controlled via a feedback system to deliver exactly the right amount of power. This allows for precise speed control, and reduces energy consumption and heat generation, extending battery life in applications where that is critical.
The brushed DC motor uses brushes and a commutator to switch current between the positive and negative sides of the motor. This causes arcing across the brushes and generates electrical noise. This noise can be reduced by adding capacitors or RC snubbers pwm servo motor driver across the brushes, but it will always occur to some degree. With a BLDC motor, however, there is no contact between the rotor and stator, so the noise generated by the instantaneous switching of current is much lower. The result is a quieter, more reliable motor.
Noise
When a BLDC motor is running, it creates electromagnetic vibration. This is caused by electromagnetic forces that interact with the air-gap magnetic field of the permanent magnets and the established magnetic potential of the stator coils. This can lead to resonance of the motor core and the shafts and bearings.
These vibrations can also generate electrical noise, a phenomenon called arcing. This noise occurs when the brushes and commutator switch instantaneously open and close, generating an electric current. Arcing can be mitigated by adding capacitors and RC snubbers, but it is still inevitable.
Noise measurements were performed at twenty-four equally spaced points on a cylindrical surface surrounding the motor. These measurements were used to reconstruct particle velocity on the source surfaces using measurement pressure. Results confirmed that reconstructed particle velocity accurately identified sources of motor noise, including electro-magnetic force excitation and structural or acoustical resonance by the housing. Radiated sound from the top cooling holes on the housing and the switching of the brushes were dominant sources at 84 Hz and 508 Hz respectively.
Maintenance
BLDC motors don’t have brushes or a commutator, which means they require very little maintenance. However, they do need to be used in accordance with their published specifications and in a clean environment. They also need to be inspected regularly to ensure they are running properly.
One of the most common reasons for a BLDC motor to fail is the commutator. The commutator is the piece of motor winding that switches current between the rotor and stator. If the commutator isn’t properly maintained, it can cause the motor to lose speed and become overheated.
If the commutator isn’t working correctly, it can damage the coils in the stator or even burn them out. If you notice any signs of commutator damage, it’s important to fix them immediately. You can test the commutator’s performance by using a voltage megohm meter.
