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EE-463 STATIC POWER CONVERSION-I

Controlled Rectifiers

Ozan Keysan

keysan.me

Office: C-113 Tel: 210 7586

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Thyristor Rectifiers

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Thyristor Rectifiers

  • HVDC Transmission Systems

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Thyristor Rectifiers

  • HVDC Transmission Systems

  • DC Motor Drives

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Thyristor Rectifiers

  • HVDC Transmission Systems

  • DC Motor Drives

  • Traction Applications

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Thyristor Rectifiers

  • HVDC Transmission Systems

  • DC Motor Drives

  • Traction Applications

  • Industrial Loads (Welding, Heating etc)

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Thyristor Rectifiers

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Thyristor Rectifiers

General Schematic

Drawing

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Thyristor Rectifiers

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Thyristor Rectifiers

Operating Quadrants

Drawing

Capable of supplying negative Vd (Q4, Inversion)

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Simple Circuits

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Simple Circuits

Thyristor with R load

Drawing

Can you plot the voltage output?

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Simple Circuits

Thyristor with R load

Drawing

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Simple Circuits

Thyristor with RL load

Drawing

Can you plot the voltage output?

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Simple Circuits

Thyristor with RL load

Drawing

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Simple Circuits

Load with DC Source

Drawing

Can you plot the voltage output?

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Load with DC Source

Drawing

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Thyristor with RL load

but let's add a freewheeling diode

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Thyristor with RL load

but let's add a freewheeling diode

Drawing

What are the differences?

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Thyristor with freewheeling diode

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Thyristor with freewheeling diode

Drawing

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Single Phase Thyristor Rectifier

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Single Phase Thyristor Rectifier

Drawing

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Single Phase Thyristor Rectifier

Ideal Case

Drawing

Can you plot the output voltages?

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It is identical to diode rectifier with α=0

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It is identical to diode rectifier with α=0

Drawing

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What about with a large firing angle?

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What about with a large firing angle?

Drawing

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How can you calculate the average voltage?

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How can you calculate the average voltage?

Vdα=22Vsπcos(α)

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How can you calculate the average voltage?

Vdα=22Vsπcos(α)

  • α=0 Diode rectifier

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How can you calculate the average voltage?

Vdα=22Vsπcos(α)

  • α=0 Diode rectifier

  • α<π/2Vd>0

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How can you calculate the average voltage?

Vdα=22Vsπcos(α)

  • α=0 Diode rectifier

  • α<π/2Vd>0

  • α>π/2Vd<0

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Operating Modes

Drawing

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Power Flow

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Power Flow

P=1Tp(t)dt

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Power Flow

P=1Tp(t)dt

P=Id1Tvd(t)dt=0.9VsIdcos(α)

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Line Current

Drawing

Shifted by α, but still a square wave

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Line Current

Drawing

Shifted by α, but still a square wave

Harmonics, THD, I1?

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Line Current

Drawing

Shifted by α, but still a square wave

Harmonics, THD, I1?

What about PF, DPF?

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Real Power, Apparent Power

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Real Power, Apparent Power

Drawing

MultiSim

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Single Phase Rectifier with Resistive Load

Drawing

Voltage Waveform?

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Single Phase Rectifier with Resistive Load

Drawing

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Single Phase Rectifier with Resistive Load

Drawing

Average Voltage?

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Single Phase Rectifier with Resistive Load

Drawing

Vdα=2Vsπ(1+cos(α))

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Single Phase Rectifier with R-L Load (Continuous Current)

Drawing

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Single Phase Rectifier with R-L Load (Continuous Current)

Drawing

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Single Phase Rectifier with R-L Load (Discontinuous Current)

Drawing

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Single Phase Rectifier with Freewheeling Diode

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Single Phase Rectifier with Freewheeling Diode

Drawing

Can you plot the voltage, current waveform?

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Single Phase Rectifier with Freewheeling Diode

Drawing

Can you plot the voltage, current waveform?

What are the advantages, disadvantages?

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How can you make this circuit cheaper?

Drawing

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Full Bridge Half Controlled Rectifier

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Full Bridge Half Controlled Rectifier

Drawing

D1, D2 works as freewheeling diodes

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Full Bridge Half Controlled Rectifier

Drawing

D1, D2 works as freewheeling diodes

Vd cannot be negative

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Full Bridge Half Controlled Rectifier

Alternative (Same Output)

Drawing

D3 can be removed (depending on load, and thyristor gate signals)

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Commutation

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Commutation

With source side inductance (Ls)

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Commutation

With source side inductance (Ls)

Drawing

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Commutation

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Commutation

Can you plot the voltage and current outputs?

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Commutation

Can you plot the voltage and current outputs?

Drawing

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Commutation

Effect on the output voltage

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Commutation

Effect on the output voltage

Au=2Vs(cos(α)cos(α+u))=2ωLsId

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Commutation

Effect on the output voltage

Au=2Vs(cos(α)cos(α+u))=2ωLsId

cos(α+u)=cos(α)2ωLsId2Vs

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Commutation

Voltage drop due to commutation

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Commutation

Voltage drop due to commutation

ΔVdu=Auπ=2ωLsIdπ

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Commutation

Voltage drop due to commutation

ΔVdu=Auπ=2ωLsIdπ

Vd=0.9Vscos(α)2ωLsIdπ

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Example

Mohan Ex. 6.1

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Practical Thyristor Converter

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Practical Thyristor Converter

Consider a case as a DC motor drive

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Practical Thyristor Converter

Consider a case as a DC motor drive

Drawing

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

Drawing

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

Drawing

Average voltage with commutation?

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

Drawing

Average voltage with commutation?

Vd0.9Vscos(α)2ωLsId,minπ

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

Drawing

Average Current?

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Practical Thyristor Converter

Continuous Conduction (id is always > 0)

Drawing

Average Current?

Id=VdEdrd

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Practical Thyristor Converter

What happens if Id is small?

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Practical Thyristor Converter

Discontinuous Conduction

Drawing

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Practical Thyristor Converter

Discontinuous Conduction

Drawing

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Inverter Mode

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Inverter Mode

90 < Firing Angle < 180

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Inverter Mode

90 < Firing Angle < 180

Average power<0 (Power flows from DC to AC)

Drawing

Only with active power source on DC side

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Inverter Mode

90 < Firing Angle < 180

Drawing

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Inverter Mode

Thyristor Voltage

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Inverter Mode

Thyristor Voltage

Drawing

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Inverter Mode

Thyristor Voltage

Drawing

Extinction Angle (γ=180(α+u))

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Inverter Mode

Thyristor Voltage

Drawing

Extinction Angle (γ=180(α+u))

Extinction time should be larger than thyristor turn-off time (tq)!

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You can download this presentation from: keysan.me/ee463

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Thyristor Rectifiers

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