DC/DC Converter with Transparent Electronics for application on Photovoltaic Panels

DC/DC Converter with Transparent Electronics for application on Photovoltaic Panels

DC/DC Converter with Transparent Electronics for application on Photovoltaic PanelsRomano Torres19th July 2013

1Supervisor: Vitor Grade TavaresSecond Supervisor: Pedro Miguel Cndido BarquinhaSecond Supervisor: Pydi Ganga BahubalindruniMaster of Electrical and Computers EngineeringOutlineMotivationObjectivesa-IGZO TFTsDC/DC ConverterAmplifierRegulatorFabricationConclusionsFuture Work

22MotivationTo construct circuits on flexible substracts, such as plastic, glass:Possible to embody in photovoltaic panels.

Low cost fabrication at room temperature.3

ObjectivesDesign of a boost DC/DC converter using transparent electronics in order to have an increased and stable voltage level with direct current.Vout > 1.5*Vin;Efficiency >= 40%

Fabrication of the circuit in CENIMAT/UNL.

4a-IGZO TFTsHigh parasitic resistance;

P-type transistors with low performance;

Threshold voltage shift.

5

Staggered bottom-gate TFT structureProblems:Voltage Boosting Stage DC/DC converter

6

Indutors are avoided due to their low performance in transparent technology;

Capacitor is used to save charge in electric field;

Vdd < Vout < 2*Vdd

Voltage Boosting Stage - out of phase clock signals

7

Lower variation of Vout level.2 Voltage Boosting Stages in Cascade

8

To increase the voltage level twice;

Parasitic effects reduce the efficiency;

4 TFTs of 320 m in parallel for each diode-connection are used;

Vdd < Vout > RL

Objectives: Vout 20 V 50% lower V

Advantage: More stable voltage leveleven with load variation.

Proposed Amplifier Block diagram19

Amplifier

20

Differential Stage

21

Positive Feedback Stage

22

Source-Follower Stages

23

Common-Source Stages

24

Phase Compensation

-In order to have higher phase margin.

25Gain and Phase Response

26Gain: 36.7dB

Phase Margin: 83.79

Proposed Amplifier - Layout

272383.8 m2450 m

Regulator

28Voltage levels

Vout = 17.65 VThe voltage variation with the load decreased 80%.Final Circuit - Layout

2918709.55 m14557.1 mFabrication30

DC/DC converter with bootstrapping and 2 boosting stagesConclusionsDC/DC converter:Wide transistors reduce parasitic resistance;Bootstrapping stage decreases settling time;10 converters in parallel reduce the parasitic resistance and allow more voltage boosting stages, increasing the output voltage level.Amplifier:Good phase margin was achieved;Voltage gain is enough for the regulation;Regulator:80% lower fluctuation of the voltage level with load variations.

31Improve the design of the amplifier to increase the gain;

PWM regulation with duty-cycle variation.Future Work

32The EndThank you!33