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Reference.org
Vector control (motor)
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<p>Vector control, also called field-oriented control (FOC), is a <a href="/facts/Variable-frequency_drive/N5E5olHC">variable-frequency drive</a> (VFD) control method in which the <a href="/facts/Stator/pKBWvIHI">stator</a> currents of a <a href="/facts/Three-phase/YXY3bQCx">three-phase</a> <a href="/facts/AC_motor/9RkMe7NV">AC motor</a> are identified as two orthogonal components that can be visualized with a vector. One component defines the <a href="/facts/Magnetic_flux/jQMVxrnD">magnetic flux</a> of the motor, the other the torque. The control system of the drive calculates the corresponding current component references from the flux and torque references given by the drive's speed control. Typically <a href="/facts/PI_controller/7XcYk0CH">proportional-integral (PI) controllers</a> are used to keep the measured current components at their reference values. The <a href="/facts/Pulse-width_modulation/cqjcrYs7">pulse-width modulation</a> of the variable-frequency drive defines the <a href="/facts/Transistor/Bmr8zwL0">transistor</a> switching according to the stator voltage references that are the output of the PI current controllers. </p><p>FOC is used to control <a href="/facts/Alternating_current/qxICS3xa">AC</a> <a href="/facts/Synchronous_machine/s9y1U8J4">synchronous</a> and <a href="/facts/Induction_motor/DgTnMmJM">induction motors</a>. It was originally developed for high-performance motor applications that are required to operate smoothly over the full <a href="/facts/Speed/I3qgMPfs">speed</a> range, generate full <a href="/facts/Torque/KcrcvNtV">torque</a> at zero speed, and have high dynamic performance including fast <a href="/facts/Acceleration/UVDmjYvR">acceleration</a> and <a href="/facts/Deceleration/UVDmjYvR">deceleration</a>. However, it is becoming increasingly attractive for lower performance applications as well due to FOC's motor size, cost and <a href="/facts/Electric_energy_consumption/eEl4r39x">power consumption</a> reduction superiority. It is expected that with increasing computational power of the microprocessors it will eventually nearly universally displace single-variable <a href="/facts/Scalar_control/BE11TI2T">scalar control</a> (<a href="/facts/Volt/KF18MXP2">volts</a>-per-<a href="/facts/Hertz/6Wshj5qm">Hertz</a>, V/f control). </p>