Welcome to this installment of MC² covering ac motors and drives.
A common way to classify ac motors is based on the magnetic principle that produces rotation. So there are two fundamental types of ac motors; induction motors and synchronous motors. Induction motors are more common in motion control applications, but synchronous motors do find use in applications requiring precise and constant speed.
Industrial applications such as conveyors and packaging lines require motor and drive systems that are reliable with long service life. And ac motors and drives are well suited to these and other industrial uses with high output power.
Drives for ac motors interface between a controller that sends control signals to the drive which converts those signals to currents that drive the motor. An ac motor’s speed is determined by the number of poles and the frequency. So as frequency is adjusted the motor’s speed can be controlled as well. One of the most common types of drives is a variable frequency drive (VFD), which are covered in this Motion Control Classroom.
In addition to some basics of ac motors including motors for harsh environments, cogging, and the use of soft starters, this installment of Motion Control Classroom covers the basics of VFDs as well as various motor control methods including V/Hz control as well as some different motor braking methods.
You’ll find these and many more resources on a wide array of motion control components and systems, including other MC Classroom installments, at www.designworldonline.com/mc2/.
What are AC motors? Technical Summary for Motion Engineers
An AC motor, like any electric motor, converts electrical energy to mechanical energy. AC motors take as their input an ac current, but differ from dc motors in that there is no commutation involved, and can be single or multi-phase.
When do you need a soft starter for an AC motor?
A soft starter can eliminate problems by gradually increasing voltage to the motor terminals during startup, providing a controlled ramp-up to full speed.
What is direct torque control (DTC) for AC induction motors?
Direct torque control (DTC) is similar to field oriented control, in that it decouples torque and flux and controls them independently.
FAQ: How do drives affect cogging in AC motors?
If you put two magnets in close proximity to each other, you know that they’ll experience an attractive force when opposite poles are near each other and a repulsive force when like poles are near.
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AC induction motors are used to drive loads such as fans, pumps, lifts, and conveyors. But in some applications, the motor is also used as a brake to stop the load, reverse its direction, or hold the load and prevent it from moving.
What is flux braking and how does it differ from regenerative braking
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