Inner rotor motor, as the name implies, has the rotor inside and the stator outside. When the rotor rotates, the inside rotates and the outside does not move. In contrast, the outer rotor motor has the rotor outside and the stator inside. When the rotor rotates, the inside does not move and the outside rotates.
The main differences between external rotor motors and internal rotor motors are reflected in the following aspects:
1. Structural design
Internal rotor motor: The rotor is located inside the motor and the stator surrounds the rotor. When rotating, the center part (rotor) turns and the outer housing is stationary.
External rotor motor: The rotor is located outside the motor, enclosing the stator inside. When rotating, the outer shell (rotor) turns and the internal stator is fixed.
2. Moment of inertia and dynamic response
External rotor motor: The rotor radius is large, the moment of inertia is high (J = mr2), it starts and stops slowly, but runs more smoothly, and is suitable for applications that require inertia maintenance (such as fans, hub motors).
Inner rotor motor: small moment of inertia, fast dynamic response, suitable for scenarios that require frequent starting and stopping or rapid acceleration (such as traditional robots, servo systems).
3. Heat dissipation performance
Inner rotor motor: The stator is on the outside, with a large heat dissipation area. The heat is usually dissipated directly through the outer casing, which is suitable for long-term high-load operation.
External rotor motor: The stator is on the inside, the heat dissipation path is longer, and it needs to rely on internal ventilation or axial heat dissipation, and the heat dissipation efficiency is low.
4. Torque and speed characteristics
Outer rotor motor: Due to its large rotor radius, high torque output, but low speed, it is suitable for direct drive (such as electric bicycle hubs, drone propellers).
Inner rotor motor: high speed, small torque, often used with a reducer (such as industrial motors, power tools).
5. Volume and power density
External rotor motor: compact structure, the external rotor can be integrated into the equipment (such as the wheel hub), saving space and having high power density.
Inner rotor motor: Traditional design is more common, relatively large in size, but suitable for standardized installation.
6. Application Scenarios
Typical applications of external rotors: fans, wind turbines, balancing car motors, drone rotors, and modern service robots.
Typical applications of inner rotors: CNC machine tools, electric vehicle main drives, servo motors, and household appliances.
7. Manufacturing and Cost
External rotor motor: Due to its special structure, it may involve higher dynamic balancing requirements and the manufacturing cost is slightly higher.
Inner rotor motor: mature technology, complete industrial chain, and usually lower cost.
Summary: Outer rotor motors are characterized by high torque, low speed, and compact structure, and are suitable for direct drive scenarios; inner rotor motors focus on high speed, fast response, and efficient heat dissipation, and are widely used in the industrial field. When choosing, you need to weigh performance and design complexity according to specific needs.
Shenzhen Zhongling Technology has been subordinate to the external rotor hub motor for many years. The company has gathered countless college talents and industry elites, integrating R&D, production and sales, and has been deeply involved in the service robot industry. Its customers occupy most of the domestic and foreign service robot industry. Its products are sold at home and abroad, and it is basically in a leading position in the industry. Zhongling Technology also supports various reasonable customizations, such as load capacity, speed, structure (axle, tire, brake), and will share its valuable experience and suggestions according to customer needs and actual application scenarios to help customers avoid many detours and develop robot projects better and faster.
Post time: May-27-2025