Alternator

alternator
Vectors U0 Ux Uy U7
Interval end (µs) 0.2 0.4 0.6 0.7
Vectors U7 Uy Ux U0
Interval end (µs) 0.8 0.9 1.0 1.2
L1 L H H L L L H H
L2 L L H H H L L H
L3 L L L L H H H H
Angle 60° 120° 180° 240° 300°
Vector u0 u1 u2 u3 u4 u5 u6 u7

Base Space Vectors

Space vector modulation (SVM) is an algorithm for the control of pulse width modulation (PWM). 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. There are variations of SVM that result in different quality and computational requirements. One active area of development is in the reduction of total harmonic distortion (THD) created by the rapid switching inherent to these algorithms. To implement space vector modulation, a reference signal Vref is sampled with a frequency fs (Ts = 1/fs). The reference vector is synthesized using a combination of the two adjacent active switching vectors and one or both of the zero vectors. Various strategies of selecting the order of the vectors and which zero vector(s) to use exist. Strategy selection will affect the harmonic content and the switching losses.