three-phase step-up dc–dc converter

8/3/2019 THREE-PHASE STEP-UP DCDC CONVERTER

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THREE-PHASE STEP-UP DCDC CONVERTER

Presented by

Muhammed Salih U P

S1 M-Tech

GECT

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INTRODUCTION

The great necessity in several areas, particularly theindustrial sector, for switch mode power converters with

larger power ratingsThe advantages of three-phase dcdc isolated solutions

are as follows

Reduction of the input and output filters volume

Lower rms current levels through the powercomponents

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PROPOSED CONVERTER AND THE OPERATION

PRINCIPLE

Circuit Description

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The left side of the circuit (inverter) comprises threeinductors and three switches connected to a dc link

The right side of the circuit is a traditional three-branch six-diode rectifier with a capacitive output filter

The three-phase step-up dcdc isolated converter

characteristics are as follows Inverter (left-side) circuit presents a low input ripple current

The output-voltage ripple is reduced due to the three pulse outputcurrent

Only the three switches connected to the same reference attribute

simplicity The voltage level applied across the switches is reduced due to the

employed transformer.

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Analysis of Operation

Assumptions made for analysis

Tr1 is modelled as an ideal transformer with turns ratio n = 1

Magnetizing inductance is large enough that it can be neglected

Filter capacitor C is large enough that its output-voltage ripple issmall compared to its dc voltage.

All semiconductor components are ideal

A PWM technique is used for switches S1, S2, and S3


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Operation Regions

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Each one differs from each other by the number of switches in the ON state at

the same time

Due to the converters input-current-source characteristic, at least one switchmust always be on


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Operations for Region R2

1) First Stage (t0, t1) In t0, switch S1 is turned on and conducts along with switch S3. Inductances

L1 and L3 store energy from source E.

The energy stored in L2 is transferred to the load through D2, D4, and D6

This stage finishes in t1 when S3 is turned off.

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2) Second Stage (t1, t2)

In t1, S3 is turned off, and the energy stored in L2 and L3 istransferred to the load through D3, D2, and D4

This stage finishes in t2 when S2 is turned on

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Third Stage (t2, t3)

In t2, the energy of source Eis stored in inductances L1 and L2. The energy stored in L3 continues to be transferred to the load through D3,

D4, and D5.

This stage finishes in t3 when S1 is turned off

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4) Fourth stage (t3, t4)

In t3, the energy stored in L1 and L3 is transferred to the load through D1, D3,and D5

This stage finishes in t4 when S3 is turned on.the switches for the converteroperation in region R2

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5) Fifth Stage (t4, t5)

In t4, the energy of source Eis stored in inductances L2 and L3

The energy stored in L1 continues to be transferred to the load through D1,D5, and D6.


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6) Sixth Stage (t5, t6)

The converters last stage of operation in a TSswitching period starts at t5,when S2 is turned off.

The energy from source Estored in inductances L2 and L1 is then transferredto the load through D1, D2, and D6.

In t6, a switching period is finished.

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(a) Command pulses.

(b)L1 inductor current.

(c)L2 inductor voltage.

(d)D1 output diode current.

(e)D5 andD6 diode currents.

(f) S1 switch current.

(g) Output capacitor current.

(h) Primary winding voltage.

(i) Primary winding current.


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Region R3

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Steady-State Stage Operations for Region R3

First Stage (t0, t1) In t0, switch S1 is turned on and conducts along with switches S2 and S3.

Inductances L1, L2, and L3 stored energy from source E.


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2) Second Stage (t1, t2)

In t1, S2 is turned off, and the energy stored in L2 is transferredto the load through diodes D2, D4, and D6.

This stage finishes in t2 when S2 is turned on

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Third Stage (t2, t3)

In t2, S2 is turned on, and the first stage is repeated, with the energy of thesource being stored in inductances L1, L2, and L3.


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4) Fourth Stage (t3, t4)

When S3 is turned off, the energy stored in L3 is transferred to the loadthrough D3, D4, and D5.

This stage finishes in t4 when S3 is turned on again.

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5) Fifth Stage (t4, t5)

In t4, S3 is turned on, and the first stage is repeated, with the energy off thesource being stored in inductances L1, L2, and L3.


6) Sixth Stage (t5, t6)

The last stage starts at t5, with S1 being turned off and the energy stored ininductance L1 being transferred to the load through diodes D1, D5, and D6.

In t6, one period of switching operation is concluded.

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(a) Command pulses.

(b) L1 inductor current.

(c) L2 inductor voltage.

(d) D1 output diode current.

(e) D5 and D6 diode currents.

(f) S1 switch current.

(g) Output capacitor current.

(h) Primary winding voltage.

(i) Primary winding current.

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III. POWER STAGE

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IV. DC TRANSFER FUNCTION

Three modes of conduction of the converter

can be observed.

The output/ input voltage gain q or the dc

transfer function for operation areaR2 in CCM

is limited to a maximum of three times the

transformers turns ratio The duty cycle must be higher than 33% for

the correct functionality of the converter

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V. CONTROL DESIGN

The average current-mode control technique applied to theregulation of both input current and output voltage of theconverter

There are two loops, namely, inner current loop and outer voltageloop

Gi(s) is the control-to-input-current transfer function, where thecontrolled variable is the input current IE(s) and the controlvariable is the duty ratio d(s).

Gv(s) is the line-to-output or input current-to-output-voltagetransfer function.

Ci(s) and Cv(s) are the current and voltage compensators,respectively.

Vref and Iref are the references to be reached.

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CONCLUSION

The three-phase step-up dcdc isolated converter controlled by anaverage current-mode strategy has greater efficiency with reducedweight and size.

This converter can be used in all applications that require areduced input ripple current, e.g., in industrial applications where

the dc input voltage is lower than the output voltage, for instance,in installations fed by battery units, PV arrays, or FC systems.

Control model employed is simple, with its very satisfactoryresults.

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REFERENCES


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REFERENCES

[1] Srgio Vidal Garcia Oliveira and Ivo Barbi A Three-Phase Step-Up DCDC ConverterWith a Three-Phase High-Frequency Transformer for DC Renewable Power Source

Applications in IEEE Trans Industrial electronics ., vol. 58, no. 8, Aug. 2011. [2] D. S. Oliveira, Jr. and I. Barbi, A three-phase ZVS PWM DC/DC converter with

asymmetrical duty cycle associated with a three-phase version of the hybridge rectifier,IEEE Trans. Power Electron., vol. 20, no. 2, pp. 354360, Mar. 2005.

[3] S. V. G. Oliveira and I. Barbi, A three-phase step-up DCDC converter with a three-phase high frequency transformer, in Proc. IEEE ISIE, Jun. 2023, 2005, vol. 2, pp. 571

576. [4] C. P. Dick, A. Konig, and R.W. De Doncker, Comparison of three-phase DCDC

converters vs. single-phase DCDC converters, in Proc. 7th Int.Conf. PEDS, Nov. 2730,2007, pp. 217224.

[5] P. D. Ziogas, A. R. Prazad, and S. Manias, Analysis and design of the three-phase off-line DCDC converter with high frequency isolation, in Conf. Rec. IEEE IAS Annu.

Meeting, 1988, pp. 813820.

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three-phase step-up dc–dc converter

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