PWM "SpaceVector "
The space vector PWM (vector space) is particularly applicable to variable speed three-phase without neutral.
It is generally considered a three-phase system, and apply to a transform Concordia to bring in the (Vα, Vβ). The three-phase system of voltages generates for the duration of sampling in progress can then be represented as a single vector in the plane.
This vector is not directly achievable through the switches of the drive, but you can find the three closest configurations (located on the vertices and center of the hexagon), and successively applied for a fraction of the appropriate period of 'sampling, in order to obtain an average vector sought.
Sinusoidal modulation gives similar results to the PWM triangular carrier intersection centered. However, it may be easier to implement in a microcontroller, and a harmonic Assistant 3 maximizes the available power, which justifies its use.