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Space vector modulation (SVM) is an algorithm for the control of pulse-width modulation (PWM), invented by Gerhard Pfaff, Alois Weschta, and Albert Wick in 1982. [1] [2] It is used for the creation of alternating current (AC) waveforms; most commonly to drive 3 phase AC powered motors at varying speeds from DC using multiple class-D amplifiers.
Fig. 4 shows the conduction states of the system, and from this we get the input space vectors shows in Fig. 5 [12] Fig 5: Conduction states of the Vienna Rectifier, for ia>0, ib,ic<0, valid in a 60 o {\displaystyle 60^{o}} sector of the period T1 sa, sb, and sc characterise the switching state of the system.
It may also be noted that since the DC bus voltage is shared by at least two power valves, their voltage ratings can be less than a two-level counterpart. Carrier-based and space-vector modulation techniques are used for multilevel topologies. The methods for these techniques follow those of classic inverters, but with added complexity.
Space vector modulation is a PWM control algorithm for multi-phase AC generation, in which the reference signal is sampled regularly; after each sample, non-zero active switching vectors adjacent to the reference vector and one or more of the zero switching vectors are selected for the appropriate fraction of the sampling period in order to ...
Thus, a of zero indicates that the system is balanced (and thus exists entirely in the alpha-beta coordinate space), and can be ignored for two coordinate calculations that operate under this assumption that the system is balanced. This is the elegance of the clarke transform as it reduces a three component system into a two component system ...
From the end of 1990s several papers have been published about DTC and its modifications such as space vector modulation, [20] which offers constant switching frequency. In light of the mid-2000s expiration of Depenbrock's key DTC patents, it may be that other companies than ABB have included features similar to DTC in their drives. [citation ...
A three-phase inverter with a neutral leg with space vector modulation IEEE APEC '97 Conference Proceedings (1997). T.A.Lipo, “A Cartesian Vector Approach To Reference Theory of AC Machines”, Int. Conference On Electric Machines, Laussane, Sept. 18–24, 1984.
Since the electric dipole moment is a vector (tensor of the first rank), the diagonal elements of the perturbation matrix V int vanish between states that have a definite parity. Atoms and molecules possessing inversion symmetry do not have a (permanent) dipole moment and hence do not show a linear Stark effect.