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The core difference between internal rotor and external rotor brushless DC motors lies in the mounting positions of the rotor and stator. This leads to a series of differences in speed, torque, and application scenarios. Specifically, they can be distinguished from three main aspects:
1. Differences in Core Structure:
Internal Rotor Brushless DC Motor: The rotor (including permanent magnets) is located at the center of the motor, and the stator (including windings) is wrapped around the outside of the rotor; the rotor diameter is smaller, usually requiring additional heat dissipation components (such as heat sinks and fans).
External Rotor Brushless DC Motor: The stator is located at the center of the motor, and the rotor (including permanent magnets) is wrapped around the outside of the stator; the rotor diameter is larger, and most rotors integrate fan blades on the outside, eliminating the need for additional heat dissipation components.
2. Key Performance Differences:
Performance Dimensions | Internal Rotor Brushless DC Motor | External Rotor Brushless DC Motor |
Speed And Torque | High speed(typically thousands to tens of thousand of rpm), lower torque | Low speed (typically hundreds to thousands of rpm),higher torque |
Moment Of Interia | Small rotor diameter,small moment of inertia | Large rotor diameter,large moment of inertia |
Response Speed | Small moment of inertia, fast start /stop and speed adjustment response | Large moment of inertia, slower response, smoother operation |
Heat Dissipation | Stator heat dissipation relies on external components, generally ineffective | Rotor has its own fan blades, enabling active heat dissipation,resulting in better performance |
3. Typical Application Differences
Internal Rotor Brushless DC Motor: Suitable for "high-speed, low-torque, fast-response" scenarios, such as air conditioner compressors, refrigerator compressors, drone main motors, power tools (electric drills, angle grinders), automotive drive motors, etc. External rotor brushless DC motors: Suitable for low-speed, high-torque, and stable operation scenarios, such as household fans (floor fans, ceiling fans), washing machine drum motors, industrial exhaust fans, low-speed drone gimbal motors, and smart door lock drive motors.
Shenzhen Power Motor, with its solid foundation of years of experience in brushless DC motor R&D and production, keeps abreast of industry trends such as new energy, industrial automation, and low-altitude economy, focusing on the core needs of "high efficiency, intelligence, and green," and providing full-cycle services from customized R&D to mass production.
We understand motors and the industry. We are willing to work with you to seize the market with mature power solutions and create a new future for the industry!
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Note: This article is contributed by Power Motor Sales Department
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