Line-Commutated Rectifiers(Phase-Controlled Rectifiers)

Power Electronics Line-commutated Rectifiers1

Outline

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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

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Continuous conduction mode

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Discontinuous conduction mode

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Example

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The Three-Phase Bridge Rectifier

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Continuous conduction mode

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A typical CCM waveform

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Discontinuous conduction mode

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Phase control

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DC output voltage vs. delay angle α

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Inverter mode

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Transformer connections

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Twelve-pulse rectifier

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Waveforms of 12 pulse rectifier

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Rectifiers with high pulse number

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Power And Harmonics in Nonsinusoidal Systems

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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

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Energy transmitted to load, per cycle

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Evaluation of integral

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Example 1

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Example 2

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Example 3

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Example 3

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

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Power factor

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Linear resistive load, nonsinusoidal voltage

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Nonlinear dynamical load, sinusoidal voltage

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Distortion factor

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Distortion factor vs. THD

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Power phasor in sinusoidal systems

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Example: power phasor diagram

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Reactive power Q

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Lagging fundamental current of phase-controlled rectifiers

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Harmonics and power factor

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Real and reactive power in controlled rectifier at fundamental frequency

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AC line current harmonic standards

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● International Electrotechnical Commission Standard 555

● IEEE/ANSI Standard 519

Line-Commutated Rectifiers

International EletrotechnicalCommission Standard 555

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IEEE/ANSI Standard 519

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IEEE-519 current limits, low voltage systems

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IEEE-519 current limits, high voltage systems

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IEEE-519 voltage limits

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