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Published2025-10-15
The Heart of Motion—Understanding the Core Components of a Servo Motor
Servo motors are the unsung heroes powering a vast array of modern technologies—from the precise movements of robotic arms to the smooth control of drone flight. Their ability to accurately control angular or linear position, velocity, and acceleration depends fundamentally on a complex yet elegant internal structure.
At the core of a servo motor's internal architecture are several critical components, each playing a role in ensuring stable, accurate, and efficient operation. Let’s take a journey inside to explore these components and understand how they work together to produce the magic of controlled motion:
The stator forms the static part of the motor, acting as the foundation on which magnetic fields are generated. Typically made from laminated iron cores, stators contain windings—coils of copper wire—that when energized with electrical current, create electromagnetic fields. These fields are crucial because they interact with the rotor to produce torque.
The design of the stator windings is meticulous, optimized for uniform magnetic flux distribution. By carefully controlling the winding currents, engineers can precisely manipulate the magnetic fields, which directly impact the servo motor's responsiveness and accuracy. The stator's size and winding configuration also influence the motor's power output and efficiency.
Contrary to the stator, the rotor is the rotating part of the servo motor. It’s often constructed from a laminated iron core wrapped with conductors such as permanent magnets or windings, depending on the type of servo motor—whether brushed, brushless DC, or AC synchronous.
In brushless servo motors, the rotor usually contains permanent magnets made from rare-earth materials like neodymium, which provide a high magnetic flux density. The rotor's permeability and magnetic properties are crucial because they determine how easily the rotor will align with the stator's magnetic field,—a principle that underpins the motor’s precision.
3. The Commutator and Brushes (In Brushed Servo Motors)
In traditional brushed servo motors, the commutator and brushes form an essential part of the internal structure. The commutator is a rotary switch that reverses the direction of current flow in the windings, ensuring continuous torque in a single rotational direction.
While brushed motors are simpler, they have moving parts that wear over time, impacting precision and reliability. That’s why many modern servo motors favor brushless designs, which replace these components with electronic commutation—more durable and precise.
The rotor is mounted on a shaft, which is supported by bearings inside the motor housing. The bearings minimize rotational friction, allowing smooth motion and reducing wear over time. High-quality bearings are fundamental for the longevity and stability of servo motors that operate continuously under high loads.
The shaft itself transmits the mechanical torque generated inside the motor to the external mechanism—be it a robotic arm joint, a camera gimbal, or a CNC machine axis. The design and material of the shaft are crucial for maintaining accuracy without flexing or vibrations that could compromise control.
A defining feature of servo motors is their feedback loop, which ensures high accuracy and precise control. At the core of this system is typically an encoder or a resolver mounted on the rotor or integrated into the motor assembly.
Encoders: Provide digital signals representing the rotor’s position or speed. They can be incremental or absolute, depending on the resolution and application needs. Resolvers: Analog devices offering high reliability, especially in harsh environments, by converting the rotor position into electrical signals directly.
These feedback signals are processed by a control circuit or driver, which adjusts the current supplied to the motor to achieve the desired position and speed.
Kpower has delivered professional drive system solutions to over 500 enterprise clients globally with products covering various fields such as Smart Home Systems, Automatic Electronics, Robotics, Precision Agriculture, Drones, and Industrial Automation.
Update：2025-10-15
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