Motion Control Components: The BasicsJuly 14, 2022
Motor solutions are the lifeblood of many applications. They make automation systems run.
While every automated system is different, there are just as many motor types to fit each application. There are countless motor types, brands, and sizes, making motor selection a vital process.
AC motors convert electrical energy into mechanical energy, distributing an alternating current over long ranges. They are flexible and efficient and tend to operate quietly, making them ideal for use in applications like pumps, fans, blowers, and other applications that need constant, variable, or adjustable speed control.
At the basic level, AC motors consist of a stator and a rotor that contains a conductor. The motor rotates the conductor across a magnetic field to create voltage. Therefore, the conductor produces a current if it is in a closed field.
Manufacturers use AC motors for multiple reasons, including:
- Efficiency: AC motors have high speed to torque, allowing them to operate without overheating or braking.
- Brushless: Brushless motors do not create friction, which reduces heat output and increases the motor's lifespan.
- Quiet: AC motors operate with a very low humming sound.
- Simple and Accessible: they have only one moving part. They also come in various shapes and sizes with different power outputs, allowing them to fit into many applications.
- Speed Control: the frequency can be changed to control the speed of the motor.
Brushed DC Motor
Brushed DC motors are used in applications that need high peak torques and run using simple speed controllers. They are cost-efficient, easily controlled, and have a linear torque-speed relationship.
Brushed DC motors have four components: a stator, rotor, brushes, and a commutator. Basically, they operate with permanent magnets on the outside of the motor to create an electromagnetic field. Their operation allows them to produce high torque during acceleration and deceleration, making them ideal for industrial applications that involve dispensing and packaging and some robotic applications.
However, the drawbacks to using brushed DC motors are the mechanical wear and tear on the brushes and the commutator, leading to a lower lifespan. However, their low initial cost can compensate for their frequent replacement needs.
Brushless DC Motor
Brushless DC motors are similar in function to brushed DC motors, with the primary difference being that they operate without brushes. A brushless DC motor is built opposite of a brushed DC motor. While a brushed DC motor has magnets on the outside (the stator), brushless DC motors have magnets on the internal rotor. They do not use brushes to create an electromagnetic field.
Brushless DC motors are quieter, more efficient, and have longer lifespans than brushed dc motors. They can also run continuously with less heat output. These benefits come with a slightly higher initial cost. Brushless DC motors are also ideal for hazardous environments that contain dust, grease, oil, and other contaminants.
Geared DC Motor
Geared DC motors (gear motors) have a gear assembly attached. This assembly allows the motor to increase the torque and reduce speed as needed. This concept—increasing torque while decreasing speed—is known as gear reduction.
Gearmotors work in conjunction with gearboxes. They are small, with a high torque-to-size ratio, creating a smaller motor footprint.
Servo motors convert rotary to linear motion as they have position and velocity feedback. They work in mechanical systems with a feedback device like an encoder or resolver. These motors provide detailed feedback but require a controller to manage commutation and position/velocity control. Thus, the user knows the motor’s position, speed, and torque every moment, making them useful in robotics and industrial production.
Most servo motors today are brushless motors. They are accurate, reliable, and efficient and can be used in harsh environments. Also, servo motors feature high acceleration, quiet operation, and closed-loop control. They have a high torque to inertia ratio comparable to AC motors. Their downside is that they can be higher cost initially.
Need help to choose a motor for your system? Our automation experts can help. Get in touch with Motion Ai to learn more about your options.