Line-Commutated rectifiers

Line-Commutated Rectifiers(Phase-Controlled Rectifiers)

Power Electronics Line-commutated Rectifiers1

Outline

Power Electronics Line-Commutated Rectifiers2

1.The single-phase bridge rectifier● continuous conduction mode● discontinuous conduction mode

2.The three-phase bridge rectifier● continuous conduction mode● discontinuous conduction mode

3.Some issues in rectifiers● phase control● inverter mode● transformer connections

4.The concept of power and harmonics innonsinusoidal systems

The single-phase bridge rectifier


Continuous conduction mode


Discontinuous conduction mode

Power Electronics 5 Line-Commutated Rectifiers

Example


The Three-Phase Bridge Rectifier


Continuous conduction mode


A typical CCM waveform


Discontinuous conduction mode


Phase control


DC output voltage vs. delay angle α


Inverter mode


Transformer connections


Twelve-pulse rectifier


Waveforms of 12 pulse rectifier


Rectifiers with high pulse number


Power And Harmonics in Nonsinusoidal Systems

Power Electronics 18

Average power in terms of Fourier series

RMS value of a waveform Power factor

THDDistortion and Displacement factors

Power phasors in sinusoidal systemsAC line current harmonic standards

Line-Commutated Rectifiers

Average power


Energy transmitted to load, per cycle


Evaluation of integral


Example 1


Example 2


Example 3


Root-mean-square (RMS) value of a waveform, in terms of Fourier series


Power factor


Linear resistive load, nonsinusoidal voltage


Nonlinear dynamical load, sinusoidal voltage


Distortion factor


Distortion factor vs. THD


Power phasor in sinusoidal systems


Example: power phasor diagram


Reactive power Q


Lagging fundamental current of phase-controlled rectifiers


Harmonics and power factor


Real and reactive power in controlled rectifier at fundamental frequency


AC line current harmonic standards


● International Electrotechnical Commission Standard 555

● IEEE/ANSI Standard 519

Line-Commutated Rectifiers

International EletrotechnicalCommission Standard 555


IEEE/ANSI Standard 519


IEEE-519 current limits, low voltage systems


IEEE-519 current limits, high voltage systems


IEEE-519 voltage limits


Line-Commutated rectifiers

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