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A permanent magnet synchronous motor and reluctance motor requires a control system for operating (VFD or servo drive). There is a large number of control methods for synchronous machines, selected depending on the construction of the electric motor and the scope. Control methods can be divided into: [21] [22] Scalar control. V/f control ...
Self-starting polyphase induction motors produce torque even at standstill. Available squirrel-cage induction motor starting methods include direct-on-line starting, reduced-voltage reactor or auto-transformer starting, star-delta starting or, increasingly, new solid-state soft assemblies and, of course, variable frequency drives (VFDs). [39]
Reduced starting current is desirable where the electrical grid is not of sufficient capacity, or where the driven load cannot withstand high starting torque. One basic method to reduce the starting current is with a reduced voltage autotransformer with taps at 50%, 65% and 80% of the applied line voltage; once the motor is started the ...
It is used to dampen the transient oscillations and facilitate the start-up operation. [ 2 ] Since the design of a damper winding is similar to that of a asynchronous motor , the winding technically enables the direct-on-line start and can even be used for the motor operation in the asynchronous mode.
In the asynchronous category, we have induction motors, while the synchronous group contains permanent-magnet and current-excited motors. Induction motors have been around since the 19th century.
A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network ...
Hysteresis synchronous motors typically are (essentially) two-phase motors with a phase-shifting capacitor for one phase. They start like induction motors, but when slip rate decreases sufficiently, the rotor (a smooth cylinder) becomes temporarily magnetized. Its distributed poles make it act like a permanent magnet synchronous motor.
In vector control, an AC induction or synchronous motor is controlled under all operating conditions like a separately excited DC motor. [21] That is, the AC motor behaves like a DC motor in which the field flux linkage and armature flux linkage created by the respective field and armature (or torque component) currents are orthogonally aligned such that, when torque is controlled, the field ...