Space vector modulation

One active area of development is in the reduction of total harmonic distortion (THD) created by the rapid switching inherent to these algorithms.

Note that looking down the columns for the active switching vectors V1-6, the output voltages vary as a pulsed sinusoid, with each leg offset by 120 degrees of phase angle.

To implement space vector modulation, a reference signal Vref is sampled with a frequency fs (Ts = 1/fs).

Strategy selection will affect the harmonic content and the switching losses [de].

More complicated SVM strategies for the unbalanced operation of four-leg three-phase inverters do exist.

Topology of a basic three-phase inverter
All eight possible switching vectors for a three-leg inverter using space vector modulation. An example V ref is shown in the first sector. V ref_MAX is the maximum amplitude of V ref before non-linear overmodulation is reached.