LCL filter, also called line filter, is specially designed to suppress the switching frequency components caused by the rectifiers’ semiconductors (IGBTs). It consists of a parallel-series combination of reactors and capacitors adapted to reduce the THD(i) of rectifiers.
- Active supply unit is controlled to eliminate low order harmonics in the current
- Line filter suppresses components above the switching frequency of the active supply unit IGBTs
In an ABB low harmonic drive, the use of Direct Torque Control (DTC) principles, together with a low pass filter, will suppress the current harmonic content leaving total harmonic distortion (THD) of less than 3%. The resulting clean sinusoidal current will therefore cause little or no distortion on the network voltage waveform.