EE464-Static Power Conversion-II

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# EE-464 STATIC POWER CONVERSION-II

# DC/DC Converters Continued

## Ozan Keysan

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

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

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<img src="./images/ee464/slobodan_cuk.jpg" alt="Drawing" style="width: 400px;"/>
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## [Slobodan Ćuk](https://en.wikipedia.org/wiki/Slobodan_%C4%86uk)
### [Linked-in profile](https://www.linkedin.com/in/slobodancuk/)

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# Ćuk converter

### Supplies a negative voltage
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### Reduced EMI and bi-directional power flow
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### C1 is the primary energy storage element (should be large)

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# Ćuk converter

## Can you plot the on & off states?
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## ON State

### Diode off (reverse biased by C1)

### \\(i\_{L1}\\) and \\(i\_{L2}\\) passes through T1
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### C1 discharges through T1 (\\(V\_{C1}>V\_{o}\\))
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## OFF State

### Diode on
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### \\(i\_{L1}\\) decreases  (\\(V\_{C1}>V\_{d}\\)) 
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### C1 charges through D1 (from input and L1)
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## Operating States

<img src="./images/ee464/cuk_inductor_voltage.png" alt="Drawing" style="width: 500px;"/>
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## Operating States

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# Ćuk converter

#\\(V_o = \dfrac{D}{(1-D)} V_d\\)

## It is a buck-boost converter!

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# [Input/Output Ripple](https://www.eetimes.com/document.asp?doc_id=1273276&page_number=1)?

<img src="./images/ee464/dc_dc_ripples.jpg" alt="Drawing" style="width: 450px;"/>
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# Ćuk converter

## Double ended: Inductors placed at both the input and the output
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# Ćuk converter

## Advantages:

- ## Both input and output currents are ripple free (fed through inductors)
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- ## Lower filtering requirements
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- ## Constant source current

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# Ćuk converter

## Disadvantages:
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- ## Capacitor(C1) is quite bulky
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- ## Capacitor (C1) should have a large ripple current rating
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- ## Complex circuit

#### For curious students: [Power Electronics Manifesto](https://www.youtube.com/watch?v=DDDy-i2fYg0) by Slobodan Ćuk

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# Practical Product: [LM2611](http://www.ti.com/product/LM2611)

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# Practical Product: [LM2611](http://www.ti.com/product/LM2611)

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# Example
## Mohan Exercise 7-3
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# SEPIC Converter
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## Single Ended Primary Inductor Converter
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### Essentially a boost converter cascaded with a buck-boost converter

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# SEPIC Converter

### Popular in battery powered systems (voltage level can be adjusted according to charge level)
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### Possible to shutdown completely (when the switch is off)

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## [Operating Modes](http://www.all-electronics.de/wp-content/uploads/migrated/document/114418/502ag0207.pdf):

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## [Operating Modes](http://www.all-electronics.de/wp-content/uploads/migrated/document/114418/502ag0207.pdf): ON State

## \\(v\_{L1}=Vs\\)

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##  [Operating Modes](http://www.all-electronics.de/wp-content/uploads/migrated/document/114418/502ag0207.pdf): OFF State

## \\(-V\_s + v\_{L1}  + v\_{C1} + V\_{o}=0\\)
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## If \\( v\_{C1} =V\_{s} \\) then \\(v\_{L1} = -V\_{o}\\)

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##  [Operating Modes](http://www.all-electronics.de/wp-content/uploads/migrated/document/114418/502ag0207.pdf): Currents

<img src="./images/ee464/sepic_current.png" alt="Drawing" style="width: 700px;">
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# Example (Handout)

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# SEPIC With Mutually Coupled Inductors

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# SEPIC Converter
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## Advantages:

- ### Non-inverting buck-boost converter
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- ### Energy Efficient (can be completely turned-off)

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## Disadvantages:

- ### Pulsating output current
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- ### Large capacitance (and large ripple current rating)
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- ### Fourth order transfer function, difficult to control

- ### Energy Efficient (can be completely turned-off)

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# SEPIC Converter
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## Inductors can be combined is a single core (coupled inductors)

## Lower required inductance, and size
 
## Minimize oscillation in the circuit (more on that later)

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# Interleaved Converters
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## Interleaved Buck Converter
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# Interleaved Converters

## Interleaved Buck Converter

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# Interleaved Converters

## Interleaved Boost Converter

<img src="./images/ee464/interleaved_boost.png" alt="Drawing" style="width: 700px;">
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# Reading Assignments

- ### [TI Training Videos](https://training.ti.com/world-power)

- ### [MATLAB Topology Comparison](https://www.mathworks.com/matlabcentral/fileexchange/60167-dc-to-dc--buck-boost-buck-boost-sepic-cuk--converters?s_tid=gn_loc_drop)

- ### [Application Note: Designing A SEPIC Converter](http://www.all-electronics.de/wp-content/uploads/migrated/document/114418/502ag0207.pdf)

- ### [Sepic and Ćuk Converters](http://www.idc-online.com/technical_references/pdfs/electrical_engineering/C_uK_and_Sepic_Converter.pdf)

- ### [Sepic Converter Basics](https://www.youtube.com/watch?v=m5OG_3-sbCs)

- ### [Power supply topology: SEPIC vs Flyback](https://www.electronicsweekly.com/news/products/analog/power-supply-topology-sepic-vs-flyback-2005-11/)

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