Solar inverter

1. SINGLE PHASE SOFT SWITCHING GRID
TIED MICROINVERTER FOR
PHOTOVOLTAIC APPLICATIONS
Presented by,
Vijisha.E.V
S3, M.Tech
VAS15EEPE08
Guide:
Dr. Nimal Madhu M.
Associate Professor
VAST
1

2. INTRODUCTION
• Solar photovoltaic energy is most common among the
renewable power generation systems.
• Hence, grid integration of this technology is crucial for
effective utilization of this technique.
• This can be facilitated by means of a DC-DC-AC
converter
• Microinverter offers high efficiency and power
capacity than other topologies.
2

3. • PV inverter topology with galvanic isolation is
preferred for the microinverter.
• Proposed microinverter has the structure to minimize
power losses.
• Soft switching technique should be employed to
improve the efficiency in the proposed inverter.
• Maximum power point tracking(MPPT) is used to
extract maximum power from the PV system.
3
INTRODUCTION

4. OBJECTIVE
• Development of microinverter with soft switching
operation for harnessing solar power and delivering it
to the grid.
4

5. 5
PROPOSED SYSTEM

6. Operation States of DC-DC Stage
6
• MODE 1[t0, t1]

7. 7
• MODE 2[t1, t2]
•
𝑑𝑖𝐿𝑚
𝑑𝑡
=
𝑉𝑃𝑉
𝐿𝑚
•
𝑑𝑖𝑠
𝑑𝑡
=
𝑛𝑉𝑃𝑉−𝑉𝐶𝑟
𝐿1𝑘
𝑉𝑃𝑉 - Input Voltage
𝐿𝑚 – Magnetizing Inductance
𝑉𝐶𝑟 - Resonant Capacitor Voltage
𝐿1𝑘 – Leakage Inductance
𝑖𝑠 - Secondary current
𝑖𝐿𝑚 - Magnetizing Current

8. 8
• MODE 3[t2, t3]
• MODE 4[t3, t4]

9. 9
• MODE 5[t4, t5]
•
𝑑𝑖𝐿𝑚
𝑑𝑡
=
𝑉𝑃𝑉−𝑉𝑐
𝐿𝑚
= −
𝐷
1−𝐷
𝑉𝑑
𝐿𝑚
𝑉𝑑 - Output Voltage
D – Duty ratio
𝑉
𝑐 - Active clamp capacitor voltage
• MODE 6 [t5, t6]

10. Theoretical Waveforms Of The Proposed Dc–Dc Stage
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11. OPERATION STATES OF PROPOSED
INVERTER
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 In The Positive Grid Voltage

12. 12
 In the Negative Grid Voltage

13. CIRCUIT SPECIFICATIONS
13
SL
NO
PARAMETERS SYMBOLS VALUE
1 PV Voltage Vpv 45-75V
2 Output Voltage (dc-dc stage) Vd 350V
3 Grid Voltage Vg 220Vrms
4 Switching Frequency(dc-dc
stage)
fs,dc 50kHz
4 Inverter Switching frequency fs 16kHz
5 Clamp Capacitor Cc 2.2 μF
6 Resonant Capacitor Cr 2.4 μF
7 Turn Ratio N1:N2 9:38
8 Magnetizing Inductance Lm 20 μH
9 Leakage Inductance L1k 2.6H
10 Inverter Filter Inductance Lp, Ln 15mH

14. SIMULATION BLOCK OF DC-DC STAGE
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15. Output Voltage Waveform
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16. Trigger Signals for Switches S1& S2
16

17. Voltage & Current Waveforms of the Switch S1
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18. Voltage & Current Waveforms of the Switch S2
18

19. Voltage & Current Waveform of Diode Dr1
19

20. Voltage & Current waveform of the Diode Dr2
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21. SIMULATION BLOCK OF INVERTER STAGE
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22. Trigger Signals for Switches
22

23. Alterations…
• Thyristors on Ac side are replaced by MOSFET Switches
23

24. REFERENCES
[1] N. Sukesh, M. Pahlevaninezhad, and P. K. Jain, “Analysis and
implementation of a single-stage flyback PV microinverter
with soft switching,” IEEE Trans. Ind. Electron., vol. 61,
no. 4, pp. 1819–1833, Apr. 2014.
[2] Y. Xue, L. Chang, S. B. Kjær, J. Bordonau, and T. Shimizu, “
Topologies of single- phase inverters for small distributed
power generators: An overview,” IEEE Trans. Power
Electron., vol. 19, no. 5, pp. 1305–1314, Sep. 2004.
[3] R. W. Erickson and A. P. Rogers, “A microinverter for
building-integrated photovoltaics,” in Proc. IEEE Appl.
Power Electron. Conf. Expo., Feb. 2009, pp. 911–917.
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25. [4] W. Y. Choi, “High-efficiency DC-DC converter with fast
dynamic response for low-voltage photovoltaic
sources,” IEEE Trans. Power Electron., vol. 28, no. 2, pp.
706–716, Feb. 2013.
[5] D. Meneses et al., “Single-stage grid-connected forward
microinverter with constant off-time boundary mode control,”
in Proc. IEEE Appl. Power Electron. Conf. Expo., Feb. 2012,
pp. 568–574.
[6] T. Yan, J. Xu, F. Zhang, J. Sha, and Z. Dong, “Variable-on-
time- controlled critical-conduction- mode flyback
PFC converter,” IEEE Trans. Ind. Elec-tron., vol. 61, no.
11, pp. 6091–6099, Nov. 2014.
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