A Modified SEPIC Converter with High Static Gain For Renewable Applications Wind Energy Projects

 

ABSTRACT:

Two high static gain step-up DC-DC converters based on the modified SEPIC converter are presented in this paper. The proposed topologies present low switch voltage and high efficiency for low input voltage and high output voltage applications. The configurations with magnetic coupling and without magnetic coupling are presented and analyzed. The magnetic coupling allows the increase of the static gain maintaining a reduced switch voltage. The theoretical analysis and experimental results show that both structures are suitable for high static gain applications as a renewable power sources with low DC output voltage. Two experimental prototypes were developed with an input voltage equal to 15 V and an output power equal to 100 W. The efficiency at nominal power obtained with the prototype without magnetic coupling was equal to 91.9% with an output voltage of 150 V. The prototype with magnetic coupling operating with an output voltage equal to 300 V, presents an efficiency at nominal power equal to 92.2%.

KEYWORDS

  1. DC-DC power conversion
  2. Voltage multiplier and Solar power generation.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Two-stage AC module structure.

EXPECTED SIMULATION RESULTS:

Fig.2. Input current (CH4), output voltage (CH3), switch current (CH2) and voltage (CH1) of the modified SEPIC converter without magnetic coupling (10 A/div, 50 V/div,10 μs/div).

Fig. 3. Switch current (CH2) and voltage (CH1) of the modified SEPIC converter without magnetic coupling (10 A/div, 50 V/div, 2.5 μs/div).

Fig.4. L1 (CH4) and L2 (CH2) inductor current of the Modified SEPIC converter without magnetic coupling (10 A/div, 10 μs/div).

Fig.5. Output diode Do voltage (CH1) and current (CH4) of the modified SEPIC converter without magnetic coupling (5 A/div, 50 V/div, 5 μs/div).

Fig.6. Reverse recovery current of the output diode Do (CH4) and output diode Voltage (CH1) of the modified SEPIC converter without magnetic coupling (2 A/div, 50 V/div, 100 ns/div).

Fig.7. Input current (CH4), output voltage (CH3), switch current (CH2) and switch voltage (CH1) of the Modified SEPIC converter with magnetic coupling and voltage multiplier (10 A/div, 50 V/div,10 μs/div).

Fig. 8. Switch current (CH2) and switch voltage (CH1) of the Modified SEPIC converter with magnetic coupling and voltage multiplier (2 A/div, 50 V/div, 1 μs/div).

Fig. 9. L1 (CH3) and L2 (CH4) inductor current of the Modified SEPIC converter with magnetic coupling (5 A/div, 10 μs/div).

Fig.10. Output diode Do voltage (CH1) and current (CH2) of the Modified SEPIC converter with magnetic coupling (2 A/div, 50 V/div, 2.5 μs/div).

Fig.11. Input current (CH3), output voltage (CH2), switch current (CH4) and switch voltage (CH1) of the Modified SEPIC converter with magnetic coupling and voltage multiplier operating with Vi=15 V and Po=50 W (5 A/div, 50 V/div, 5 μs/div).

Fig.12. Input current (CH3), output voltage (CH2), switch current (CH4) and switch voltage (CH1) of the Modified SEPIC converter with magnetic coupling and voltage multiplier operating with Vi=24 V and Po=50 W (5 A/div, 50 V/div, 5 μs/div).

CONCLUSION:

Two new topologies of non isolated high static gain converters are presented in this paper. The first topology without magnetic coupling can operate with a static gain higher than 10 with a reduced switch voltage. The structure with magnetic coupling can operate with static gain higher than 20 maintaining low the switch voltage. The efficiency of proposed converter without magnetic coupling is equal to 91.9% operating with input voltage equal to 15 V, output voltage equal 150 V and output power equal 100 W.

The efficiency of proposed converter with magnetic coupling is equal to 92.2% operating with input voltage equal to 15 V, output voltage equal 300 V and output power equal 100 W. The commutation losses of the proposed converter with magnetic coupling are reduced due to the presence of the transformer leakage inductance and the secondary voltage multiplier that operates as a non dissipative clamping circuit to the output diode voltage.

REFERENCES:

[1] C. W. Li, X. He, “Review of Non-Isolated High Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications”, IEEE Transactions on Industrial Electronics, vol. 58, no. 4, pp.1239-1250, April 2011.

[2] C. S. B. Kjaer, J. K. Pedersen and F. Blaabjerg, “A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules”, IEEE Transactions on Industry Applications, vol. 41, no. 5, pp. 1292-1306, September 2005.

[3] D. Meneses, F. Blaabjerg, O. Garcia and J. A. Cobos, “Review and Comparison of Step-Up Transformerless Topologies for Photovoltaic AC-Module Application”, IEEE Transactions on Power Electronics, vol. 28, no. 6, pp. 2649- 2663, June 2013.

[4] D. Zhou, A. Pietkiewicz and S. Cuk, “A Three-Switch High-Voltage Converter”, IEEE Transactions on Power Electronics, vol. 14, no. 1, pp. 177-183, January 1999.

[5] M. Prudente, L. L. Pfitscher, G. Emmendoerfer, E. F. Romaneli and R. Gules, “Voltage Multiplier Cells Applied to Non-Isolated DC–DC Converters”, IEEE Transactions on Power Electronics, vol. 23, no 2, pp. 871-887, March 2008.

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