1

DESIGN AND IMPLEMENTATION OF TRANSFORMERLESS INVERTER WITH DC CURRENT ELIMINATION

Presented By,

SUDHIN P.K

PGEE02012

Guided By Dr. Sasidharan Sreedharan

2

CONTENTS

OBJECTIVE MOTIVATION LITERATURE REVIEW PROPOSED CONVERTER COMPLETE MODEL – BLOCK DIAGRAM EXPECTED OUTCOME GANTT CHART REFERENCES

3

OBJECTIVE

Phase I : i. Simulation : Transformerless Inverter Modelii. Hardware implementation of Transformerless

inverter (Off Grid Model)

Phase II :i. PLL Designii. Grid Integration of Developed Model

4

MOTIVATION

Increasing demand of PV system Development of Cost Effective system Complete elimination of CM leakage current

5

WHY ‘LESS’ TOPOLOGY?

Most Commercial PV inverters employ either line-frequency or high-frequency isolation transformers.

Increases – Size,Cost,Losses Transformerless Topology – Reduced Size,

weight, cost and installation complexity Increases efficiency by 2% produces Common Mode Leakage Current

6

THE COMMON MODE LEAKAGE CURRENT,

increases the system losses

reduces the grid connected current quality

induces severe conducted and radiated

electromagnetic interference

causes personal safety problems.

7

8

Full H Bridge Topology [5] Half H Bridge Topology [5]

I. Simple Structure

II. High EMI

III. High Common mode Leakage Current

I. Simple Structure

II. High EMI

III. High Common mode Leakage Current

IV. High Voltage Stress across switches

Literature Review

9

HERIC Topology [6] H5 Topology [7]

I. Large number of Switches

II. Low EMI

III. Low Common mode Leakage Current

I. Less number of Switches

II. Low EMI

III. Low Common mode Leakage Current

10

PROPOSED TOPOLOGY : CONCEPT

11

PROPOSED TOPOLOGY

12

COMPARISON WITH PATENTED TOPOLOGIES

HERIC(Sunways)

H5 Topology(SMA)

Proposed Topology

Input Capacitors 1 1

1 (but one additional switched capacitor)

Input Capacitance low low low

Switches 6 5 5

Diodes 2 0 0

No of output voltage Levels

3 3 3

Leakage Current Very Low Very Low Nil

13

COMPLETE MODEL

DC-DCCONVERTER(MPPT)

TRANSFORMER-LESS INVERTER

LOAD/GRID

MICRO CONTROLLER

MICROCONTROLLER

12/24 V(DC)

400 V(DC)

220 V(AC)

Vpv,Ipv

TriggeringPulses

TriggeringPulses (SPWM)

14

EXPECTED OUTCOME Simulation and Hardware implementation of

Transformerless Inverter with complete DC current elimination.

Less voltage and current stress on switches in comparison with HERIC and H5 Topology

15

GANTT CHART

16

REFERENCES

[1] Gu, Yunjie, Wuhua Li, Yi Zhao, Bo Yang, Chushan Li, and Xiangning He.

"Transformerless Inverter with Virtual DC Bus Concept for Cost Effective Grid-

connected PV Power Systems." (2013): 1-1.

[2] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-

connected inverters for photovoltaic modules,” IEEE Trans. Ind.Appl., vol. 41, no. 5,

pp. 1292–1306, Sep./Oct. 2005.

[3] T. Kerekes, R. Teodorescu, P. Rodr´ıguez, G. V´azquez, and E. Aldabas, “A new

high-efficiency single-phase transformerless PV inverter topology,”IEEE Trans. Ind.

Electron., vol. 58, no. 1, pp. 184–191, Jan. 2011.

17

REFERENCES

[4] Yang, Bo, Wuhua Li, Yunjie Gu, Wenfeng Cui, and Xiangning He. "Improved

transformerless inverter with common-mode leakage current elimination for a

photovoltaic grid-connected power system." Power Electronics, IEEE Transactions

on 27, no. 2 (2012): 752-762.

[5] Patrao, Iván, Emilio Figueres, Fran González-Espín, and Gabriel Garcerá.

"Transformerless topologies for grid-connected single-phase photovoltaic

inverters." Renewable and Sustainable Energy Reviews 15, no. 7 (2011): 3423-3431.

[6] S. Heribert, S. Christoph, and K. Juergen, German Patent HERIC

Topology,DE 10221592 A1, Apr. 2003.

[7] V. Matthias, G. Frank, B. Sven, and H. Uwe, German Patent H5-Topology,DE 102004030912 B3, Jan. 2006.