EE463-Static Power Conversion-I

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# EE-463 STATIC POWER CONVERSION-I

# Controlled Rectifiers

## Ozan Keysan

## [keysan.me](http://keysan.me)

### Office: C-113 <span class="meta">•</span> Tel: 210 7586

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# Thyristor Rectifiers
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- ## HVDC Transmission Systems
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- ## DC Motor Drives
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- ## Traction Applications

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- ## Industrial Loads (Welding, Heating etc)

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# Thyristor Rectifiers
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## General Schematic
<img src="./images/ee463/thyristor_rectifier.png" alt="Drawing" style="width: 500px;"/>

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# Thyristor Rectifiers
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## Operating Quadrants

### Capable of supplying negative Vd (Q4, Inversion)
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# Simple Circuits
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## Thyristor with R load

### Can you plot the voltage output?

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# Simple Circuits

## Thyristor with R load

<img src="./images/ee463/thyristor_R_output.png" alt="Drawing" style="width: 800px;"/>
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# Simple Circuits

## Thyristor with RL load

### Can you plot the voltage output?

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# Simple Circuits

## Thyristor with RL load

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# Simple Circuits

## Load with DC Source

### Can you plot the voltage output?

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## Load with DC Source

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## Thyristor with RL load
## but let's add a freewheeling diode
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## What are the differences?

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## Thyristor with freewheeling diode
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# Single Phase Thyristor Rectifier
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# Single Phase Thyristor Rectifier

## Ideal Case

### Can you plot the output voltages?

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## It is identical to diode rectifier with \\(\alpha=0\\)
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## What about with a large firing angle?
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## How can you calculate the average voltage?
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## \\(Vd_\alpha= \dfrac{2\sqrt{2}Vs}{\pi} cos(\alpha)\\)
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- ### \\(\alpha = 0 \rightarrow\\) Diode rectifier
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- ### \\(\alpha < \pi/2 \rightarrow Vd >0\\) 
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- ### \\(\alpha > \pi/2 \rightarrow Vd < 0\\)

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# Operating Modes

<img src="./images/ee463/thyristor_operating_modes.png" alt="Drawing" style="width: 750px;"/>
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# Power Flow
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### \\(P = \dfrac{1}{T}\int p(t) dt\\)

### \\(P = I_d \dfrac{1}{T}\int v_d(t) dt = 0.9 V_s I_d cos(\alpha)\\)

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# Line Current

### Shifted by \\(\alpha\\), but still a square wave
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## Harmonics, THD, I1?
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## What about PF, DPF?

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## Real Power, Apparent Power
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### [MultiSim](https://www.multisim.com/content/kRQKTtG5FCPiYqpQ89p5jD/controlled-rectifier)

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## Single Phase Rectifier with Resistive Load

### Voltage Waveform?

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## Single Phase Rectifier with Resistive Load

### Average Voltage?

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## Single Phase Rectifier with Resistive Load

### \\(Vd_\alpha= \dfrac{\sqrt{2}Vs}{\pi} (1+ cos(\alpha))\\)

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

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

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

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## Single Phase Rectifier with Freewheeling Diode
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## Can you plot the voltage, current waveform?
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## What are the advantages, disadvantages?

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# How can you make this circuit cheaper?

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# Full Bridge Half Controlled Rectifier
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## D1, D2 works as freewheeling diodes
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## Vd cannot be negative

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# Full Bridge Half Controlled Rectifier

## Alternative (Same Output)

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

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# Commutation
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## With source side inductance (Ls)
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# Commutation
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## Can you plot the voltage and current outputs?
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<img src="./images/ee463/thyristor_commutation.png" alt="Drawing" style="width: 700px;"/>
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# Commutation

## Effect on the output voltage
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### \\(A_u =  \sqrt{2}V_s (cos (\alpha) - cos (\alpha + u)) = 2\omega L_s I_d\\)
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### \\(cos(\alpha + u) = cos (\alpha) - \dfrac{2\omega L_s I_d}{\sqrt{2}V_s}\\)
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# Commutation

## Voltage drop due to commutation
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### \\(\Delta V\_{du} = \dfrac{A_u}{\pi} = \dfrac{2\omega L_s I_d}{\pi}\\)
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### \\(V_d = 0.9 V_s cos(\alpha) - \dfrac{2\omega L_s I_d}{\pi} \\)

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# Example

## Mohan Ex. 6.1

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## Practical Thyristor Converter
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### Consider a case as a DC motor drive