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How does brushless motor work?

Views: 4     Author: Site Editor     Publish Time: 2023-08-01      Origin: Site Inquire

Introduction of Brushless Motor

Types of Electric Motors

Electric motors are generally classified into four categories: Universal, Alternating Current (AC), Brushed Direct Current (DC), and Brushless DC motors. Among these, the Universal motor is not a preferred choice for drones due to its low efficiency, poor speed regulation, and optimal performance at very high RPMs, which is not ideal for precise speed control required for steady drone flight. Instead, Universal motors are commonly used in industrial tools and home appliances like vacuum cleaners and drills.

The AC motor operates by inducing its rotor to spin using alternating current and is usually used when connected to a wall outlet. However, if powered by batteries, an AC motor would require a transformer to function.

A DC motor is similar to an AC motor but is wired to use direct current instead of AC. While a DC motor can power a drone, it is not as efficient as the Brushless DC motor.

As the name suggests, Brushless DC motors do not use brushes, unlike Brushed DC motors. Instead, the copper coils carrying charge are directly connected to the stator, eliminating the need for brushes to connect the power supply with the rotor. Brushless motors have several advantages that make them an ideal choice for drone design, including high efficiency, wide speed ranges, and high speed-torque capabilities. Additionally, they are relatively affordable and require less maintenance compared to Brushed DC motors, which require frequent brush replacement.

How Does a Brushless Motor Work?

Rotor and Stator

To activate the motor, an electric current is delivered to one of the electromagnets, which causes the rotor to start spinning as the like-electromagnet repels the permanent magnet and tries to align with an opposite permanent magnet on the stator.

However, this initial spin is short-lived as the electromagnet and opposite permanent magnet eventually align. To sustain the rotation, another electromagnet is powered, followed by the next, and so on.

A three-phase current at a specific frequency can be delivered to the motor to control its speed, with a higher frequency signal resulting in a higher motor speed. The throttle on a drone's controller is used to adjust the motor's speed, with a higher throttle input corresponding to a higher frequency signal. The Electronic Speed Controller (ESC) plays a crucial role in regulating the signal delivery to the motor, ensuring that the motor's speed matches the desired throttle input.

The brushless motor operates by sending an electric current through coils positioned within a permanent magnetic field. As the current flows through the coils, it generates magnetic fields that cause the coils to move. Each coil is pulled away from one pole and then towards the opposite pole of the magnetic field, resulting in a rotating motion.

To maintain the rotation, the current must be continually reversed to ensure that the polarity of the coils constantly changes. This causes the coils to "chase" other stationary poles.

To supply power to the coils, permanent conductive brushes make contact with a rotating commutator. The commutator is responsible for reversing the current that flows across the coils, and its movement is what differentiates the DC brush motor from other types of motors. The commutator and brushes are essential components of the DC brush motor that enable its operation.

Application of Brushless Motor

A three-coil BLDC motor requires six electric wires (two for each coil) that are connected to the coils. In most cases, three of these wires are internally connected, while the remaining three wires protrude from the motor's body (unlike in brushed motors where only two wires protrude from the brushes). The main advantage of BLDC motors is their high efficiency, as they can operate continuously at maximum torque and rotation force. In contrast, brushed motors can only produce maximum torque at low RPMs. To achieve the same level of torque as a brushless motor, an electric brush motor would need much larger magnets. Therefore, even the smallest BLDC motor can provide more power.

BLDC motors also have a longer lifespan and generate less electrical noise due to the absence of brushes. Brush motors wear out due to continuous contact between the commutator and brushes, which can also cause sparks. Electrical noise is often caused by strong sparks that occur in the gaps between the brushes and commutator. This is why BLDC motors are preferred in situations where minimizing electrical noise is crucial.

Due to their high efficiency, long lifespan, and low electrical noise, BLDC motors find a wide range of applications. They are commonly used in drones, electric vehicles, and industrial machinery. In the automotive industry, BLDC motors are used in electric power steering systems, windshield wipers, and other applications that require high efficiency and reliability. In the aerospace industry, BLDC motors are used in aircraft actuators and control systems. Additionally, they are often used in household appliances, such as air conditioners 、refrigerators、AGV, due to their energy efficiency and quiet operation.

Classification of brushless motor

The following shows the selection of our different brushless motors. If you are preparing for a high-precision, high-speed motor, brushless motors are also a good choice. If you want to know more information, you can also contact us directly. E-mail:

Brushless Motor Manufacturer Video

HOLRY MOTOR, Our company has been committed to motor manufacturing for more than ten years, specializing in the production of brushless motors. Also known as permanent magnet synchronous motors, these motors feature high efficiency, low noise, brushless commutation and extremely low maintenance requirements. Our team has extensive knowledge and skills in the production and sales of brushless motors, whose products are widely used in various industries such as automotive, aerospace, medical, home appliances and industrial automation. We take pride in providing high-quality products that meet the diverse needs of our customers.

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