ACmachines

ACmachines, often described as alternating-current machines, are electrical devices that operate on alternating current. They are used to convert electrical energy to mechanical energy (motors) or mechanical energy to electrical energy (generators). The defining feature is the use of an AC source to produce a rotating magnetic field in the stator, which interacts with the rotor to generate torque or induce voltage.

The two principal classes are induction machines and synchronous machines. Induction machines, the most common type, have a stator supplied with AC; the rotating magnetic field induces currents in the rotor, producing torque. Rotor designs include squirrel-cage and wound-rotor configurations. Their speed is close to, but slightly below, the synchronous speed, determined by supply frequency and rotor slip. Synchronous machines use a rotor with direct current excitation or permanent magnets; the rotor speed locks to the electrical frequency, enabling precise speed and stable grid operation. They can operate as motors or as generators.

Construction and performance: In induction machines, simple rotors and rugged design give low maintenance. In synchronous machines, DC excitation controls torque and power factor; permanent-magnet and PM-assisted solutions improve efficiency. Control methods for AC machines include variable-frequency drives, vector control, and direct torque control, which enable variable speed and torque profiles.

Applications: Induction motors power pumps, fans, conveyors, and machine tools in industry; synchronous machines are common as large generators in power plants and wind turbines; PM synchronous motors are used in robotics and automation for high efficiency at variable speeds.

Status and notes: ACmachines are foundational components of modern electric power systems and industrial drives. Developments focus on efficiency, thermal management, noise reduction, fault tolerance, and integration with smart grids.