Many harmonic reduction methods exist. These techniques based on passive components, mixing single and three-phase diode rectifiers, and power electronics techniques as: multi-pulse rectifiers, active filters and PWM rectifiers (Fig. 1.1). They can be generally divided as:
Reduction of harmonic content in line current to a few percent allows avoiding most of the mentioned problems. Restrictions on current and voltage harmonics maintained in many countries through IEEE 519-1992 in the USA and IEC 61000-3-2/IEC 61000-3-4 in Europe standards, are associated with the popular idea of clean power.