What is a brushless motor A complete analysis from principles to advantages

In the past, brushed DC motors were widely used in various small mechanical equipment due to their simple structure and convenient control. However, they rely on carbon brushes and commutators to switch the current direction. This mechanical contact not only limits their lifespan, but also causes a series of problems such as frequent maintenance, loud noise, and spark interference.

 

The emergence of brushless motors is a powerful response to these problems. With the design of electronic controllers replacing mechanical commutators and Hall sensors assisting positioning, brushless motors have made qualitative improvements in durability, energy efficiency and intelligent control. Not only are they suitable for high-end industrial applications, they are also rapidly entering industries such as consumer electronics, new energy equipment, and robots that have extremely high requirements for stability and efficiency.

 

Brushless motors not only mean lower operation and maintenance costs and longer equipment life cycle, but also represent an opportunity to upgrade to intelligence and high precision.

 

--Collaboration mechanism of Hall sensor + electronic controller

Although the brushless DC motor (BLDC) has "DC" in its name, its control logic is much more complex than that of traditional DC motors. This complexity is its advantage, making it efficient, precise and low-maintenance. So, how does a brushless motor work? The key lies in two core components: Hall effect sensors and electronic controllers (drivers).

 

1. Brushless structure

--Current commutation without brushes

In traditional brushed motors, the current is commutated in the windings through the contact between the carbon brushes and the commutator. In brushless motors, there are no brushes or commutators. So how is the commutation action completed? The answer is: the commutation is completed by an electronic controller instead of manual work.

 

This makes the brushless motor more concise in physical structure, avoiding problems such as friction, wear and sparks, while also greatly improving reliability.

2. Hall Effect Sensor

--Provide accurate rotor position feedback

In order to achieve effective commutation, the electronic controller must know the current position of the rotor (permanent magnet) so that it can accurately switch the order of energizing the coils. This "sensing" task is given to the Hall effect sensor.

 

The Hall sensor can sense the change of the rotor magnetic field in real time and output the corresponding signal. After receiving these signals, the electronic controller decides which windings to energize next, thereby continuously driving the rotor to rotate and forming a complete closed-loop electromagnetic system.

 

From this structure, the Hall sensor is like the "eyes" of the motor, and the electronic controller is the "brain". The two work together to complete precise commutation operations.

3. Electronic controller

--The intelligent center of brushless motor

The electronic controller is not only responsible for the commutation operation, but also needs to undertake a series of functions such as current regulation, speed control, soft start protection, etc. Depending on the application, it can support:

• Square wave drive (more economical, suitable for low-cost applications)
• Sine wave drive (smoother operation, suitable for high-end scenarios)
• Hall-free solution (relies on back-EMF to detect rotor position, suitable for compact or cost-sensitive devices)

The high-performance controller can also be integrated with the encoder, PLC or host computer system to achieve closed-loop control and intelligent management.

 

-- brushless motors have three major advantages

After understanding the working principle of brushless motors, it is easier for us to understand why they can gradually replace traditional brushed motors. In order to see the difference between them more intuitively, I will analyze them from three aspects: life, efficiency, and operating performance.

1. Longer service life

--Friction -free structure, no more carbon brush wear

The biggest physical weakness of brushless motors is the constant friction between the carbon brushes and the commutator. Over time, the carbon brushes wear out, causing dust pollution and requiring regular replacement, increasing maintenance costs and downtime risks.

 

In contrast, brushless motors have no physical commutation components, and their "commutation" process is completed by electronic control, completely eliminating the source of wear. This means that brushless motors can run continuously for tens of thousands of hours or even longer, with almost no maintenance, and are particularly suitable for industrial occasions with high operating frequencies or extremely high reliability requirements.

 

2. Higher efficiency

--Electronic commutation has fast response and low energy loss

Traditional brushed motors inevitably have energy loss and commutation delay due to mechanical friction and electric sparks. Brushless motors use a highly responsive electronic commutation system with an efficiency generally above 85%-90%, which is much better than brushed motors.

 

In addition, by precisely controlling the winding excitation, the brushless motor can adjust the output power in real time according to the load, further improving the system energy efficiency. This is especially strategically valuable for B-end companies that pursue energy consumption optimization.

3. Lower noise and electromagnetic interference

--Smooth operation and more friendly

Due to the friction between the carbon brush and the commutator and the contact arc, brushed motors are often accompanied by noise, sparks, and even interfere with other electronic equipment during operation.

 

Brushless motors are spark-free and friction-free during operation. They not only have extremely low noise, but also perform better in terms of electromagnetic compatibility. They are particularly suitable for use in medical instruments, experimental equipment, office robots and other occasions where quietness and stability are required.

 

From these three aspects, we can clearly know that brushless motors are not just the lack of "brushes", but are fully upgraded in terms of control strategy, efficiency performance and long-term stability. This is the fundamental reason why it can replace brushed motors in large quantities in cutting-edge fields such as industrial automation, medical electronics, robots, and unmanned systems.

 

 

Although brushless motors are basically the same in principle, their structures can be divided into inner rotors (Inrunner) and outer rotors (Outrunner) according to the positional relationship between the rotor and the stator. Different structural types determine the applicability of the motor in terms of output characteristics, torque response, size layout, etc. For manufacturers, understanding this distinction will help to make more accurate selection and system design.

1. Inner rotor brushless motor

In an internal rotor motor, the rotor is located in the center of the motor, and the stator is surrounded by the rotor. This structure is the most common type in industrial and automation equipment, and has the following characteristics:

• Fast response and small moment of inertia: suitable for applications with frequent starts and stops or requiring high dynamic control;
• Compact size and flexible installation: easy to integrate in a small space;
• Strong high-speed capability: commonly used in CNC equipment, power tools, UAV power systems, etc.

Typical applications: industrial automation servo systems, AGV drive motors, laser scanners, medical analysis instruments, etc.

2. Outer rotor brushless motor

The structure of the outer rotor motor is exactly the opposite of the inner rotor: the stator is inside, and the rotor is outside and wraps around the stator to rotate. This structure can output higher torque due to its larger moment of inertia and longer lever arm, and is particularly suitable for scenarios with low speed and high torque requirements.

• Large output torque: more suitable for driving medium and low speed devices such as fans, flywheels, electric skateboards, etc.
• Smoother operation and better anti-interference ability: thanks to higher rotor inertia;
• Good heat dissipation performance: The rotor housing is an integral rotating body, which is conducive to air cooling.

Typical applications: DC fans, drones, smart electric skateboards, low-speed handling robots, etc.

 

3. How to choose the appropriate structure type

Application Type	Recommended structure type	Reason
High-speed precision control	Inner rotor	Small inertia, fast response, easy to control
Low speed and high torque	Outer rotor	Long lever arm, stable output, smooth operation
Limited installation space	Inner rotor	More compact and easier to integrate
High heat dissipation requirements	Outer rotor	Integral housing rotation facilitates air cooling
High-end automation/servo	Inner rotor	High control accuracy and sensitive system response

 

The type of brushless motor to be selected requires a balance between speed requirements, space constraints, output torque, control system compatibility, and other factors. VSD can provide customized suggestions and prototype verification for customers in different industries.

 

--from industrial automation to smart devices

Brushless motors are rapidly penetrating into multiple industries due to their high efficiency, durability, low noise and easy control. From traditional manufacturing to smart technology, from micro-precision equipment to large power systems, they have shown strong adaptability. The following are some typical application scenario classifications to help manufacturers quickly understand the wide range of uses of brushless motors.

 

1. Industrial Automation and Robotics

• Automated Guided Vehicles (AGVs) and handling robots: They require a power system that can run for a long time, start and stop frequently, and has high stability;
• CNC machine tools and servo platforms: They have extremely high requirements for positioning accuracy and response speed and are suitable for use with brushless servo systems;
• Automated production line equipment: can be integrated with PLC or industrial Ethernet to achieve precise control and energy consumption management.

 

2 Medical and testing equipment

• Electric operating tables, ventilators, injection pumps, etc.: require quietness, stability, and reliability;
• Molecular diagnostic and laboratory instruments: low electromagnetic interference and long-life motors are required to support high-frequency operation;
• Rehabilitation robot: requires high sensitivity and low-speed high-torque output.

 

3. Consumer electronics and smart devices

• High-end fans, vacuum cleaners, massagers and other smart home products;
• Portable travel tools such as drones, electric skateboards, and electric bicycles;
• Game controllers, PTZ, electric lenses and other high-precision control applications.

 

4. New energy and renewable energy systems

• Motors for yaw and pitch control in wind power generation systems;
• Positioning actuators in solar tracking systems;
• Electric vehicle auxiliary systems (electric water pumps, fans, seat drives).

 

With the popularization and deepening of brushless motor technology, there are many suppliers in the market, and the product quality and service level vary. For brushless motor solution manufacturers pursuing stability, sustainability and high performance, choosing a reliable motor partner is crucial.

 

As a technology-based company focusing on the research and development and manufacturing of DC motors, VSD is committed to providing global customers with high-performance, customizable brushless motor solutions, which are widely used in industries such as industrial automation, medical equipment, intelligent robots, and new energy systems.

 

Why choose VSD brushless motor

1. Diversified product lines to meet different needs

Both inner rotor and outer rotor structures are available;

Standard models cover a variety of application scenarios from micro to medium;

Supports customization of parameters such as voltage, torque, size, shaft type, interface protocol, etc.

 

2. Strong R&D capabilities and technical support

Possess more than 30 core motor technology patents;

Establish R&D cooperation with many universities and research institutions;

Provide one-stop service from selection suggestion → solution customization → prototype testing → mass production delivery.

 

3. Strict quality management system

Passed ISO9001, CE, RoHS and other international certifications;

Each motor passes multiple performance and reliability tests before leaving the factory;

Support third-party inspection and customer on-site audit.

 

4. Global customer trust and long-term cooperation

We have provided customized solutions for customers from countries such as Germany, Japan, the United States, and the United Kingdom;

There are successful cases in projects such as AGV systems, surgical equipment, power tools, and photovoltaic controllers;

The delivery of overseas orders is stable and the technical response is rapid.

 

Whether you are in the early stages of product development or are looking for a partner to optimize your existing motor solution, VSD will provide you with strong support with a professional team and mature systems.