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In practice, there is little limit to the shape of the image that can be displayed: it depends solely on the shape of phosphor on the anode(s). The first VFD was the single indication DM160 by Philips in 1959. [5] The first multi-segment VFD was a 1967 Japanese single-digit, seven-segment device made by Ise Electronics Corporation. [6]
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 ...
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 ...
With a variable-speed drive on the pump or fan, the supply can be adjusted to match demand and no extra loss is introduced. For example, when a fan is driven directly by a fixed-speed motor, the airflow is designed for the maximum demand of the system, and so will usually be higher than it needs to be.
Unlike a VFD, which is an indirect frequency changer since it uses an AC-DC stage and then a DC-AC stage, a cycloconverter is a direct frequency changer because it uses no intermediate stages. Another application is in the aerospace and airline industries. Often airplanes use 400 Hz power so a 50 Hz or 60 Hz to 400 Hz frequency converter is ...
Variable-frequency drive, on electric motors; Virtual Floppy Disk (file type), in Microsoft Virtual PC; Other uses. V.F.D., a recurring acronym in A Series of ...
The only difference between DTC and DSC is the shape of the path along which the flux vector is controlled, the former path being quasi-circular whereas the latter is hexagonal such that the switching frequency of DTC is higher than DSC. DTC is accordingly aimed at low-to-mid power drives whereas DSC is usually used for higher power drives. [6 ...
This article is a subtype of variable speed drive, of which there are many beyond just electronic means. That DoE PDF says this right in the 2nd paragraph of the first page: Speed can be controlled in a number of ways, with the most popular type of variable speed drive (VSD) being the variable frequency drive (VFD).