What is a Frameless Brushless Motor?

Frameless brushless DC motors, also known as "coreless" or "external rotor" motors, are a specialized type of electric motor that offers high efficiency, reduced size, and enhanced performance. Unlike traditional brushless DC motors, frameless motors do not have an external housing or frame. This makes them unique in design and ideal for applications where compactness, low weight, and high precision are critical. In this article, Brushless DC Motor Online Store will explore what a frameless brushless DC motor is, how it works, its advantages, and its common applications.

Frameless Brushless Motor Structure

A frameless brushless motor is a type of electric motor that lacks the external frame or casing that typical motors have. It essentially consists of two main parts:

  • Rotor (Magnetic Part): A circular shape with permanent magnets on its surface, possibly shown in red or blue for clarity. The rotor would be the central rotating part.
  • Stator (Coil Part): Surrounding the rotor, you would have coils represented by wire loops or concentric rings, generating the electromagnetic field. These could be shaded to contrast with the rotor.
  • No External Frame: Unlike typical motors, this diagram would not show a casing around the rotor and stator. Instead, the motor could be attached directly to a mechanical system, such as the shaft of a robotic arm or the wheel of a vehicle.

How Does a Frameless Brushless Motor Work?

Frameless brushless motors operate on the same principles as conventional ones, but with a few key differences due to their lack of external casing. Here's an overview of how they function:

Electromagnetic Induction: In a typical brushless motor, the stator coils are energized by an electronic controller, creating a rotating magnetic field. This magnetic field interacts with the permanent magnets on the rotor, causing the rotor to rotate.

  • No Brushes: As the name suggests, brushless motors don’t use brushes, which are present in traditional DC motors. This eliminates friction and wear from the brushes, making the motor more efficient and longer-lasting.
  • Electronic Control: Frameless brushless motors require an electronic speed controller (ESC) to manage the current supplied to the stator coils, allowing for precise control of the motor’s speed, position, and torque.
  • Direct Integration: The absence of a frame allows the rotor to be directly integrated into the system. The stator coils are typically mounted to a fixed structure, and the rotor is mounted on the shaft or housing, which makes it ideal for use in applications where space is at a premium.

Frameless brushless DC motor

Advantages of Frameless Brushless Motors

Frameless brushless motors offer several distinct advantages over conventional motors, particularly in specialized applications:

  1. Compact Design: Frameless motors are ideal for applications where size and weight are important. The absence of an outer frame allows these motors to be integrated directly into the equipment, saving space and making them ideal for smaller, more compact designs.
  2. Higher Efficiency: The brushless design eliminates the need for mechanical brushes that generate friction and heat. This results in higher efficiency and lower energy consumption compared to brushed motors.
  3. Reduced Maintenance: Since there are no brushes to wear out, frameless brushless motors require less maintenance over their lifespan. This makes them more reliable and cost-effective in the long run.
  4. Precision Control: Frameless brushless motors offer high precision and responsiveness, making them suitable for applications that require fine motor control. The lack of mechanical friction allows for smooth, efficient operation.
  5. Customization Flexibility: Frameless motors can be customized to fit the specific needs of a project or application. The motor's design can be tailored to suit various requirements for torque, speed, and size.
  6. Lower Heat Generation: The absence of brushes and other mechanical components means less heat is generated, improving the overall efficiency of the motor and ensuring that it operates at lower temperatures.

Applications of Frameless Brushless Motors

Frameless brushless motors are highly versatile and are used in a variety of applications where compactness, high efficiency, and integration with the system are essential. Some of the key applications include:

Robotics

  • Robotic Arms: Frameless motors are often used in robotic arms for precise movements. Their compact design allows them to be embedded directly into the arm, reducing size and weight while providing high torque and control.
  • Exoskeletons: These motors power exoskeletons for rehabilitation or enhancing physical strength, providing the necessary force for movement without bulky components.

Drones

Frameless motors are popular in drones due to their lightweight and high-efficiency characteristics. They provide the necessary torque for propulsion and stabilization without adding extra weight, which is crucial for maximizing flight time and maneuverability.

Electric Vehicles (EVs)

In EVs, especially in the case of smaller or specialty vehicles like scooters and bicycles, frameless brushless DC motors are used for direct integration into the drive system, saving space and weight while delivering high performance.

Aerospace and Aviation

Frameless motors are used in aerospace applications, such as actuators for flight control surfaces or unmanned aerial vehicles (UAVs). Their ability to work in confined spaces and operate efficiently is a significant advantage in these high-performance settings.

Medical Devices

In medical equipment, such as surgical robots or precise diagnostic machinery, frameless motors provide smooth and highly accurate movement. Their integration into the device’s structure allows for precise control in delicate environments.

Machine Tools

Frameless motors are used in CNC machines and other precision machinery where space, weight, and power efficiency are critical. Their design allows for direct integration into the machine’s moving parts, leading to better performance and reduced vibration.

Frameless brushless motor applications

Industrial Automation

These Frameless motors are used in conveyors, robotic arms, and other automated systems within factories. Their ability to operate without a frame allows for easier integration into complex systems and can reduce maintenance costs.

Actuators for Precision Applications

Frameless motors are often used in actuators where high precision and torque density are required, such as in optics, cameras, and other imaging systems where accurate positioning is essential.

Home Appliances

In advanced home appliances like high-end vacuum cleaners or washing machines, frameless motors can be used to drive motors that need to be compact, efficient, and powerful.

Electric Bicycles and Motorcycles

For compact, high-performance electric motors, frameless motors can be integrated directly into the wheel hubs or frame to improve efficiency and reduce the overall weight of the vehicle. 

The frameless design of the frameless brushless DC motor allows these motors to be integrated directly into various systems, offering space-saving, high power output, and flexibility for engineers and designers in cutting-edge applications.

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