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Small variable-frequency drive Chassis of above VFD (cover removed). A variable-frequency drive (VFD, or adjustable-frequency drive, adjustable-speed drive, variable-speed drive, AC drive, micro drive, inverter drive, variable voltage variable frequency drive, or drive) is a type of AC motor drive (system incorporating a motor) that controls speed and torque by varying the frequency of the ...
Direct torque control (DTC) is one method used in variable-frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors.This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the 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 ...
Most electric model trains are powered by electricity transported by the rails or by an overhead wire to the vehicle and so the electronic speed control does not have to be on board. This is however not the case for model trains with digital steering systems allowing multiple trains to run on the same track with different speed at the same time.
Variable frequency drives implement the scalar or vector control of an induction motor. With scalar control, only the magnitude and frequency of the supply voltage are controlled without phase control (absent feedback by rotor position). Scalar control is suitable for application where the load is constant.
Typically switching has to be done several times a minute in an electric stove, 120 Hz in a lamp dimmer, from few kilohertz (kHz) to tens of kHz for a motor drive and well into the tens or hundreds of kHz in audio amplifiers and computer power supplies. In frequency modulation, pulses of a fixed amplitude and duration are generated and the ...
Techniques known since the 1940s and used in military communication systems since the 1950s "spread" a radio signal over a wide frequency range several magnitudes higher than minimum requirement. The core principle of spread spectrum is the use of noise-like carrier waves, and, as the name implies, bandwidths much wider than that required for ...
Communications that were out-of-band of LPC like general-purpose input/output (GPIO) and System Management Bus (SMBus) should be tunneled through eSPI via virtual wire cycles and out-of-band message cycles respectively in order to remove those pins from motherboard designs using eSPI.