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THREE-PHASE CONTROLLED RECTIFIER


The majority of line-commutated rectifier/inverter used in industry operates on three-phase networks. Although their operation is more complex than single-phase rectifiers/inverters, they posses following advantages.
  1. Greater power transfer capability
  2. The output ripple current is reduced
The delay/firing angle is measured from the point where two line voltages are simultaneously at the same level.


THREE-PHASE WAVE FORMS

 
THREE-PHASE WAVE FORMS


EQUATIONS FOR THREE-PHASE VOLATGE

The three line-to-neutral voltages are given by (Vm is the peak phase voltage):
{V_{an}} = {V_m}\sin \omega t
{V_{bn}} = {V_m}\sin \left( {\omega t - \frac{{2\pi }}{3}} \right)
{V_{cn}} = {V_m}\sin \left( {\omega t + \frac{{2\pi }}{3}} \right)
The line to line voltages are given by:

{V_{ab}} = {V_{an}} - {V_{bn}} = \sqrt 3 {V_m}\sin \left( {\omega t + \frac{\pi }{6}} \right)
{V_{ba}} = {V_{bn}} - {V_{an}} = \sqrt 3 {V_m}\sin \left( {\omega t - \frac{{5\pi }}{6}} \right)
{V_{bc}} = {V_{bn}} - {V_{cn}} = \sqrt 3 {V_m}\sin \left( {\omega t - \frac{\pi }{2}} \right)
{V_{cb}} = {V_{cn}} - {V_{bn}} = \sqrt 3 {V_m}\sin \left( {\omega t + \frac{\pi }{2}} \right)
{V_{ca}} = {V_{cn}} - {V_{an}} = \sqrt 3 {V_m}\sin \left( {\omega t + \frac{\pi }{2}} \right)
{V_{ac}} = {V_{an}} - {V_{cn}} = \sqrt 3 {V_m}\sin \left( {\omega t - \frac{\pi }{6}} \right)
previous SINGLE-PHASE CONVERTERs
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