Harmonics

A 12 pulse variable frequency drive (VFD) will develop a harmonic signature with high magnitudes on the 11th and 13th order. The good thing is the typical harmonic signature exponentially falls off as the order goes up. This is the reason that an 18 pulse VFD will have less harmonics than a 12 pulse VFD and so on and so forth. Another advantage is the DC buss will have less distortion when a multi-pulse front end is used. Most medium voltage VFD comes standard with 24 or 36 pulse front ends. ...