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Photovoltaic Power Converter

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Presentation on theme: "Photovoltaic Power Converter"— Presentation transcript:

1 Photovoltaic Power Converter
Students: Thomas Carley Luke Ketcham Brendan Zimmer Greg Landgren Advisors: Dr. Woonki Na Dr. Brian Huggins Dr. Yufeng Lu Bradley University Department Of Electrical Engineering 11/30/11

2 Presentation Outline Summary and Overall System Block Diagram
DC Subsystem Maximum Power Point Tracking Boost Converter Testing AC Subsystem Schedule Component List

3 Project Summary Supplies DC and AC Power Photovoltaic Array
Boost Converter to step up PV voltage Maximum Power Point Tracking DC-AC converter for 120Vrms LC filter

4 System Block Diagram

5 DC Subsystem Boost Converter
Maximum Power Point Tracking (MPPT) System

6 Simulation Results

7 Boost Converter Full Bridge

8 DC Subsystem Requirements
The boost converter shall accept a voltage from the photovoltaic cells. The input voltage shall be 48 Volts. The average output shall be 200 Volts +/- 25 Volts. The voltage ripple shall be less than 3 Volts The boost converter shall perform maximum power point tracking. The PWM of the boost converter shall be regulated based on current and voltage from the PV array. The efficiency of the MPPT system shall be above 85%.

9 DC Subsystem Key Components
Inductor 1mH 25A 500uH 35A Gate Driver MOSFET or IGBT 2.5A 500V Solar Panel x 4 50W 12V MOSFET Vds = 250V Id = 110A Pdiss = 694W Heatsink

10 DC Subsystem Components
Current Sensor 30A 63-69 mV/A Sensing Op amp Used with voltage divider DSP Board TMS320F2812

11 MPPT “Perturb and Observe” method
Change Boost Converter duty cycle based on change in PV power Changing duty cycle changes the current drawn from the PV Anytime the system is not at the maximum power point, it is not at it’s most efficient point

12 MPPT Flowchart

13 Boost Without MPPT

14 Boost With MPPT

15 MPPT Circuit

16 Output Power Without MPPT

17 Output Power With MPPT

18 Solar Insolation Peoria, IL
PV Models in Simulink Made models of PVs using resources from the University of Colorado at Boulder Insolation – a measure of solar energy on an area over a given amount of time. Usually in units of W/m^2 Solar Insolation Peoria, IL Jan Feb March April May June July Aug Sep Oct Nov Dec kWh/(m^2 day) 3.271 4.109 4.642 4.921 5.239 5.740 5.880 5.727 5.639 4.562 2.957 2.721 W/m^2





23 I P V V

24 Insolation = 200, 400, 600, 800, 1000 W/m2 P I V V

25 I V P V

26 Boost Converter Lab Testing
Built boost converter from components Dr. Na provided.

27 Boost Converter Lab Testing
0 to 3.3V signal from DSP board controlling the MOSFET At a switching frequency of 10kHz with a 50% duty cycle the 5V input voltage was boosted to about 10V. Increasing duty cycle, increased Vout Decreasing duty cycle, decreased Vout After testing this setup we will be able to build our Boost converter circuit quickly.

28 DSP Board Programming Spectrum Digital eZdsp F2812
Texas Instruments Code Composer Matlab/Simulink

29 Simulink A/D Interfacing

30 Simulink PWM Generation

31 Manual PWM Duty Ratio Control

32 PWM Generation Experimental Results
80% Duty Ratio 30% Duty Ratio

33 AC Subsystem Inverter Output filter

34 AC Subsystem - Inverter
Inverter topology Inverter operation Simulations

35 AC Subsystem Inverter Topology
Inverter single phase H-bridge

36 AC Subsystem Inverter Operation - Bipolar
A reference sinusoidal waveform is compared to a triangular carrier waveform When the reference voltage is equal to the carrier voltage a transition in the switching signal occurs

37 AC Subsystem Inverter Operation - Bipolar
Simulation schematic

38 AC Subsystem Inverter Operation - Bipolar
Reference (blue) and carrier (red) waveforms Switching signal

39 AC Subsystem Inverter Operation - Bipolar
Inverter output. Switches from +Vd to -Vd

40 AC Subsystem Inverter Operation - Bipolar
Switching signal is inverted and fed to other pair of switches Switch pairs are switched simultaneously Only one reference signal needed, but performance is poor

41 AC Subsystem Inverter Operation - Unipolar
Two reference sinusoids are compared to a triangular waveform Switch pairs not switched simultaneously

42 AC Subsystem Inverter Operation - Unipolar
Simulation schematic

43 AC Subsystem Inverter Operation - Unipolar
References and carrier waves Switching signal 1 Switching signal 2 Output Image source: Tian

44 Inverter Operation - Comparison
Bipolar harmonic output Unipolar harmonic output

45 AC Subsystem - Output Filter
Inverter output includes switching harmonics Filter smoothes output

46 AC Subsystem Requirements
The AC side of the system shall invert the output of the boost converter. The output of the inverter shall be 120 Volts RMS. The output shall be 60Hz +/- 0.1Hz. The inverter output shall be filtered by a LC filter. The filter shall remove high switching frequency harmonics. Total harmonic distortion of the output shall be less than 15%.

47 AC Subsystem Key Components
Inverter switches Gate drives Power supplies

48 Commercial Grid Tie Inverters
Company SMA Solar Technology Xantrex Product Sunny Boy 700-US GT2.8 AC Power 460W, 120Vac 2700 W, 208Vac / 2800W, 240Vac AC Voltage Output Vac Vac / Vac Output Frequency Hz Harmonics > 3% Max. efficiency 92.4% 94.6% Power Factor Unity > 0.95 %

49 Schedule

50 Component List

51 References “PV Module Simulink Models.” ECEN2060. University of Colorado Boulder. Rozenblat, Lazar. "A Grid Tie Inverter for Solar Systems." Grid Tie Inverter Schematic and Principles of Operation. 6 Oct < Tafticht, T., K. Agbossou, M. Doumbia, and A. Cheriti. "An Improved Maximum Power Point Tracking Method for Photovoltaic Systems." Renewable Energy 33.7 (2008): Tian, Yi. ANALYSIS, SIMULATION AND DSP BASED IMPLEMENTATION OF ASYMMETRIC THREE-LEVEL SINGLE-PHASE INVERTER IN SOLAR POWER SYSTEM. Thesis. Florida State University, 2007.  Zhou, Lining. EVALUATION AND DSP BASED IMPLEMENTATION OF PWM APPROACHES FOR SINGLE-PHASE DC-AC CONVERTERS. Thesis. Florida State University, 2005.

52 Questions?

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