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In electrical engineering, three-phase electric power systems have at least three conductors carrying alternating voltages that are offset in time by one-third of the period. A three-phase system may be arranged in delta (∆) or star (Y) (also denoted as wye in some areas, as symbolically it is similar to the letter 'Y').
A three-phase induction motor has a simple design, inherently high starting torque and high efficiency. Such motors are applied in industry for many applications. A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 hp (7.5 kW) are uncommon. Three ...
In either case, the output waveforms are phase shifted to obtain a 12-step waveform. If additional inverters are combined, an 18-step inverter is obtained with three inverters etc. Although inverters are usually combined for the purpose of achieving increased voltage or current ratings, the quality of the waveform is improved as well.
The three phase currents lag their corresponding phase voltages by . The α {\displaystyle \alpha } - β {\displaystyle \beta } axis is shown with the α {\displaystyle \alpha } axis aligned with phase 'A'.
The PWM rectifier is controlled in a way that a sinusoidal AC line current is drawn, which is in phase or anti-phase (for energy feedback) with the corresponding AC line phase voltage. Due to the DC-link storage element, there is the advantage that both converter stages are to a large extent decoupled for control purposes.
It is widely used in analysis of three-phase electric power circuits. The Y-Δ transform can be considered a special case of the star-mesh transform for three resistors. In mathematics, the Y-Δ transform plays an important role in theory of circular planar graphs. [2]
As an example, the Park transformation is often used in order to simplify the analysis of three-phase synchronous machines or to simplify calculations for the control of three-phase inverters. In analysis of three-phase synchronous machines, the transformation transfers three-phase stator and rotor quantities into a single rotating reference ...
A soft-switching three-level inverter (S3L inverter) is a high-efficiency power electronic inverter intended, in particular, for use with three-phase drives, as a grid-tie inverter for photovoltaic installations or wind turbines and in power supplies. [1] The topology was developed in 2009 at HTWG Konstanz (Constance University of Applied ...