Types & Comparison of Motors in Motion Control
Motors have been produced for a wide range of applications. Before implementing motion control into a complex system, it is important to weigh the benefits and drawbacks of each type of motor.
Types of Motors
Servo motors have built-in encoders that function as feedback sensors. These sensors collect data about the positioning and speed of the rotor, enabling servo motors to operate with high precision and consistency.
Brushed DC (single phase)
Brushed DC motors are simple motors that rely on magnetic fields to move the rotor. With less complex technology than many of its counterparts, the brushed DC motor can offer reliable performance at a relatively cheap price. However, the motors experience constant friction which can cause wear out over time.
Brushless DC (three-phase)
Evolving from the brushed DC motor, the brushless DC motor is designed to operate in more compact spaces, though without sacrificing performance. In brushless motors, electricity is run through the stator rather than a coil of wires as in brushed motors. While the brushless motor can be more expensive than its predecessor, they generally last longer and require less maintenance.
Similar to DC motors, brushless AC motors run electric current through a stator and feature magnets in the rotor. The difference is that AC motors run a constant electric current, offering a much smoother rotation. Brushless AC motors are highly efficient. As a result, they are very popular among Motion Control experts and professionals.
Other Rotary Motors
Stepper motors have an internal rotor that is influenced by external magnets. After a winding effect produces energy, the teeth of the rotor turn in fixed steps. Because of their incremental movement, stepper motors offer utility as they can change speed and direction.
The AC induction motor is one of the most widely deployed motor types in industry and heavy machinery. What differentiates the induction motor from the rotary motors mentioned above is that induction motors do not use permanent magnets. They rely on a rotating magnetic field generated in the stator to induce rotation of the rotor.
As the name suggests, linear motors can be thought of as an unrolled brushless motor. They are designed using the same underlying magnetic theory, but they operate in an open form. One major benefit of using a linear motor is speed.
Linear Actuators combine technology from both rotary motors and linear motors to produce a cost-effective machine that has increased functionality in comparison to the motors above. However there are trade-offs, with actuators giving up speed and compactfullness.
Stepper motors versus small servo motors
Both stepper motors and small servo motors offer increased versatility. The servo motor is more dynamic, packing up to three times more torque than steppers. But steppers could be an effective alternative for those considering costs as they are less expensive.
Servo motors versus vector motors in positioning
Servo motors and vector motors can both be useful in positioning applications depending on system needs. Because vector motors possess significant amounts of inertia, they are best suited for heavy loads. In contrast, servo motors process lighter loads but do so more rapidly.
Rotary motors (plus rotary-to-linear devices) versus linear motors
When choosing between rotary motors or linear motors, be sure to clearly define your goals. The two main considerations should be speed and accuracy, but cost can play a major factor. Linear motors can have substantially greater upfront costs.
Considering which motor to implement into your system? Learn more about each type of motor and find suppliers through MCMA's Products and Services directory.
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