EE464-Static Power Conversion-II

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# EE-464 STATIC POWER CONVERSION-II

# Bridge Converters

## Ozan Keysan

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

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

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# Full Bridge Isolating Converter

### Compact solution for high power levels (>500W)

### Similar to push-pull converter (but with reduced voltage stress on switches)

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## Full Bridge Converter: Operating Modes
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### S1 & S2, S3 & S4 operate alternatively

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## Full Bridge Converter: Operating Modes

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## Full Bridge Converter

# \\(V_o = 2 V_s  (\dfrac{N_s}{N_p})D\\)

## \\(D < 0.5\\)

## Same with the push-pull converter

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# Half Bridge Isolating Converter

### Derived from the Buck Converter
 
### S1, S2 turned on alternatively each for \\(t\_{on}\\), then both off for \\(\Delta\\)

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## Half Bridge Converter: Operating Modes

<img src="./images/ee464/half_bridge_operating.png" alt="Drawing" style="width: 800px;">
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## Half Bridge Converter: Operating Modes

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## Half Bridge Converter

# \\(V_o = V_s  (\dfrac{N_s}{N_p})D\\)
## \\(D < 0.5\\)

## Half of the push-pull converter

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# Dual Active Full Bridge (DAB) Converter
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- ### Bi-directional poser transfer
- ### Higher efficiency can be achieved with synchronous rectification
- ### Possible to have zero voltage switching (to be covered in resonant converters)
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# Dual Active Full Bridge (DAB) Converter
### Example Design

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# Dual Active Full Bridge (DAB) Converter
## Example Design

<img src="https://toshiba.semicon-storage.com/content/dam/toshiba-ss-v3/master/en/semiconductor/design-development/referencedesign/en/board_img/RD170_photo.jpg" alt="Drawing" style="width: 800px;">
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# Current Source Converter
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- ## Voltage Source Inverter (VSI): Fed by a voltage source (i.e. a capacitor large enough)

- ## Current Source Inverter (VCI): Fed by a current source (i.e. an inductor large enough)

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# Current Source Converter

## Fed with constant source current (due to large source inductance)

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# Current Source Converter

## Same with push-pull, but the inductance moved to the source side

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# Voltage Source Converter:

## Do not turn both switches ON (to prevent short-circuit)
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# Current Source Converter

## Do not turn both switches OFF (to prevent open-circuit)

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# Current Source Converter: Operating Modes

## Notice the overlapping periods between switches

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# Current Source Converter: Operating Modes

## Diode currents are added at the output

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# Current Source Converter
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# \\(V_o = V_s  (\dfrac{N_s}{N_p})(\dfrac{1}{2(1-D)})\\)

## \\(D > 0.5\\)

# Operates as a: Boost Converter

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# PFC?
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## Power Factor Correction

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## Power Factor of a 1Ph Diode Rectifier?
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## Diode Rectifier

### Source current

<img src="./images/ee464/pfc_diode_waveform.png" alt="Drawing" style="width: 700px;">
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# PFC required for many applications
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- ### Computer Power Supplies, LED Drives
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- ### Arc Furnaces
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- ### Welding

<img src="https://cdn11.bigcommerce.com/s-x3ki4mm/images/stencil/1280x1280/products/879/1198/Askaynak-inverter-405-welding-inverter__42671.1477329188.jpg" alt="Drawing" style="width: 300px;">
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# PFC Circuit
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# PFC Current
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# PFC Current

## Critical Current Mode (Discontinuous Current Mode)
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# PFC Effect
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# PFC Alternatives: Bridgeless PFC

#### Replaces diode bridge rectifier with 2 MOSFETS + 2 diodes

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# PFC Alternatives: Bridgeless PFC

#### Replaces diode bridge rectifier with 2 MOSFETS + 2 diodes

### [PFC Circuits](https://toshiba.semicon-storage.com/info/docget.jsp?did=68570)
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# PFC Alternatives: Totem-Pole Bridgeless PFC

#### 2 MOSFETs in series (or 4 MOSFETS configuration)

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# PFC Alternatives: Totem-Pole Bridgeless PFC

### [6.6-kW Totem-Pole PFC Reference](https://www.ti.com/lit/ug/tidue54b/tidue54b.pdf)
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# PFC Alternatives: Totem-Pole Bridgeless PFC

### [6.6-kW Totem-Pole PFC Reference](https://www.ti.com/lit/ug/tidue54b/tidue54b.pdf)
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## Commercial PFC Controllers
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- ### [Toshiba-TB6819AFG](https://toshiba.semicon-storage.com/eu/semiconductor/product/power-management-ics/detail.TB6819AFG.html)

- ### [OnSemi PFC Controllers](http://www.onsemi.com/PowerSolutions/parametrics.do?id=981)

- ### [TI PFC Controllers](http://www.ti.com/power-management/offline-isolated-dcdc-controllers-converters/factor-correction/products.html#p1694=Single-phase%20PFC&p1131=CCM)

- ### [TI UCC28180](http://www.ti.com/product/UCC28180/datasheet/abstract#SLUSBQ56054)

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## PFC Application Study: Welding Circuit
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<img src="./images/ee464/pfc_welding.png" alt="Drawing" style="width: 800px;">
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# Multi-Quadrant DC Converters

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# First Quadrant Converter

### (Type A Chopper)

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# Second Quadrant Converter

### (Type B Chopper)

### Io:negative

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# Two Quadrant Converter

### (Type C Chopper)

### Io:negative

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# First and Fourth Quadrant Converter

<img src="./images/ee464/first_fourth_quadrant.png" alt="Drawing" style="width: 600px;">
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# Full-Bridge (Four Quadrant) DC-DC Converter

## Simplified Circuit

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# Full-Bridge (Four Quadrant) DC-DC Converter

## Suitable for four quadrant operation
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# Control of Full-Bridge Converter

- ## Bi-polar Voltage Switching

- ## Uni-polar Voltage Switching
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# Bi-polar Voltage Switching

### \\(T\_{A+}\\) and \\(T\_{B-}\\) are turn on and off together

### \\(T\_{A-}\\) and \\(T\_{B+}\\) are complimentary of \\(T\_{A+}\\) and \\(T\_{B-}\\)

## Output can be \\(+V\_d\\) or \\(-V\_d\\)

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# Bi-polar Voltage Switching

<img src="./images/ee464/bipolar1.png" alt="Drawing" style="width: 600px;">
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# Bi-polar Voltage Switching

<img src="./images/ee464/bipolar2.png" alt="Drawing" style="width: 700px;">
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# Bi-polar Voltage Switching

# \\(V\_o = V\_d \dfrac{v\_{control}}{\hat{V}\_{tri}}\\)

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# Uni-polar Voltage Switching

### \\(T\_{A+}\\) and \\(T\_{B+}\\) are controlled seperately

### \\(T\_{A-}\\) and \\(T\_{B-}\\) are complimetary of \\(T\_{A+}\\) and \\(T\_{B+}\\)
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## Output can be \\(+V\_d\\) or \\(0\\) or \\(-V\_d\\)

## \\(V\_o = 0 \\) if \\(T\_{A+}\\) and \\(T\_{B+}\\) are ON
## \\(V\_o = 0 \\) if \\(T\_{A-}\\) and \\(T\_{B-}\\) are ON

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# Uni-polar Voltage Switching

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# Uni-polar Voltage Switching

<img src="./images/ee464/unipolar2.png" alt="Drawing" style="width: 700px;">
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# Uni-polar Voltage Switching

# \\(V\_o = V\_d \dfrac{v\_{control}}{\hat{V}\_{tri}}\\)
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# So, what's the point?

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# Ripple Comparison

### Homework:  Mohan Example 7.4

### a) Bipolar PWM, b) Unipolar PWM

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# Dead Time (Blanking Time)

### Off periods are added to compensate with non-zero turn-off time

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# Dead Time

## Introduces non-linearity between Vref and Vo.

## Pulses shorter than dead-time will be omitted (introduce harmonics)

## Vref can be increased to compensate for the off period.

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## Full Bridge as a DC Converter

### Operate it with Constant Reference Voltage

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## Full Bridge as an Inverter

## Just change the reference voltage with a sinusoid
<img src="https://i.stack.imgur.com/KLyAy.png" alt="Drawing" style="width: 800px;">

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## Full Bridge as an Inverter

### Will be covered in detail in the following weeks

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# Comparison of DC/DC Converters

## Buck, boost, buck-boost, Cuk conveters all supply power in one direction

## Full-bridge is capable of working in four quadrants (bidirectional power flow)

# Switch Utilization

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## You can download this presentation from: [keysan.me/ee464](http://keysan.me/ee464)