High-Gain Single-Stage Boosting Inverter for Photovoltaic Applications  

ABSTRACT:

This paper introduces a high-gain single-stage boosting inverter (SSBI) for alternative energy generation. As compared to the traditional two-stage approach, the SSBI has a simpler topology and a lower component count. One cycle control was employed to generate ac voltage output. This paper presents theoretical analysis, simulation and experimental results obtained from a 200 W prototype. The experimental results reveal that the proposed SSBI can achieve high dc input voltage boosting, good dc–ac power decoupling, good quality of ac output waveform, and good conversion efficiency

 KEYWORDS:

  1. Microinverter
  2. One cycle control (OCC)
  3. Tapped inductor (TI)

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 Fig.1. Topology of the proposed SSBI

 EXPECTED SIMULATION RESULTS:

 Fig. 2. Simulated waveforms of the proposed SSBI on the line frequency scale.

Fig. 3. Simulated waveforms of the SSBI’s output voltage Vac , dc-link voltage Vdc , and dc input source current Ig with the TI operating at the CCM–DCM boundary (Po = Pob ).

Fig. 4. Simulated waveforms of the SSBI’s output voltage Vac , dc-link voltage Vdc , and dc input source current Ig : (a) illustrating the undistorted output voltage Vac , when SSBI is operated in deep DCM just above the minimum power level Po > Pomin and (b) illustrating the peak-shaving distortion of the output voltage Vac for Po < Pomin

 CONCLUSION:

A high-gain SSBI for alternative energy generation applications is presented in this paper. The proposed topology employs a TI to attain high-input voltage stepup and, consequently, allows operation from low dc input voltage. This paper presented principles of operation, theoretical analysis of continuous and discontinuous modes including gain and voltage and current stresses. To facilitate this report, two stand-alone prototypes one for 48 V input and another for 35 V input were built and experimentally tested. Theoretical findings stand in good agreement with simulation and experimental results. Acceptable efficiency was attained with low-voltage input source. The proposed SSBI topology has the advantage of high voltage stepup which can be further increased adjusting the TI turns ratio. The SSBI allows decoupled control functions. By adjusting the boost duty cycle Dbst, the SSBI can control the dc-link voltage, whereas the output waveform can be shaped by varying the buck duty cycleDbk. The ac–dc power decoupling is attained on the high-voltage dc link and therefore requires a relatively low capacitance value. The OCC control method was applied to shape the output voltage. OCC’s fast response and low sensitivity to dc-bus voltage ripple allowed applying yet smaller decoupling capacitor value, and has demonstrated low THD output for different types of highly nonlinear loads.

REFERENCES:

[1] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of singlephase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292–1306, Sep. 2005.

[2] D. C. Martins and R. Demonti, “Interconnection of a photovoltaic panels array to a single-phase utility line from a static conversion system,” in Proc. IEEE Power Electron. Spec. Conf., 2000, pp. 1207–1211.

[3] Q. Li and P.Wolfs, “A current fed two-inductor boost converter with an integrated magnetic structure and passive lossless snubbers for photovoltaic module integrated converter applications,” IEEE Trans. Power Electron., vol. 22, no. 1, pp. 309–321, Jan. 2007.

[4] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “Power inverter topologies for photovoltaic modules—A review,” in Proc. Ind. Appl. Conf., 2002, vol. 2, pp. 782–788.

[5] C. Vartak, A. Abramovitz, and K. M. Smedley, “Analysis and design of energy regenerative snubber for transformer isolated converters,” IEEE Trans. Power Electron., vol. 29, no. 11, pp. 6030–6040, Nov. 2014.

High-Gain Single-Stage Boosting Inverter for Photovoltaic Applications

 

ABSTRACT

This paper introduces a high-gain single-stage boosting inverter (SSBI) for alternative energy generation. As compared to the traditional two-stage approach, the SSBI has a simpler topology and a lower component count. One cycle control was employed to generate ac voltage output. This paper presents theoretical analysis, simulation and experimental results obtained from a 200 W prototype. The experimental results reveal that the proposed SSBI can achieve high dc input voltage boosting, good dc–ac power decoupling, good quality of ac output waveform, and good conversion efficiency.

 

KEYWORDS

  1. Microinverter
  2. one cycle control (OCC)
  3. tapped inductor (TI)

 

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig.1. Topology of the proposed SSBI.

EXPECTED SIMULATION RESULTS

Fig. 2. Simulated waveforms of the proposed SSBI on the line frequency

scale.

Fig. 3. Simulated waveforms of the SSBI’s output voltage Vac , dc-link voltage Vdc , and dc input source current Ig with the TI operating at the CCM–DCM boundary (Po = Pob ).

Fig. 4. Simulated waveforms of the SSBI’s output voltage Vac , dc-link voltage Vdc , and dc input source current Ig : (a) illustrating the undistorted output voltage Vac , when SSBI is operated in deep DCM just above the minimum power level Po > Pomin and (b) illustrating the peak-shaving distortion of the output voltage Vac for Po < Pomin .

CONCLUSION

A high-gain SSBI for alternative energy generation applications is presented in this paper. The proposed topology employs a TI to attain high-input voltage stepup and, consequently, allows   operation from low dc input voltage. This paper presented principles of operation, theoretical analysis of continuous and discontinuous modes including gain and voltage and current stresses. To facilitate this report, two stand-alone prototypes one for 48 V input and another for 35 V input were built and experimentally tested. Theoretical findings stand in good agreement with simulation and experimental results. Acceptable efficiency was attained with low-voltage input source. The proposed SSBI topology has the advantage of high voltage stepup which can be further increased adjusting the TI turns ratio. The SSBI allows decoupled control functions. By adjusting the boost duty cycle Dbst, the SSBI can control the dc-link voltage, whereas the output waveform can be shaped by varying the buck duty cycleDbk. The ac–dc power decoupling is attained on the high-voltage dc link and therefore requires a relatively low capacitance value. The OCC control method was applied to shape the output voltage. OCC’s fast response and low sensitivity to dc-bus voltage ripple allowed applying yet smaller decoupling capacitor value, and has demonstrated low THD output for different types of highly nonlinear loads.

 

REFERENCES

[1] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of singlephase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1292–1306, Sep. 2005.

[2] D. C. Martins and R. Demonti, “Interconnection of a photovoltaic panels array to a single-phase utility line from a static conversion system,” in Proc. IEEE Power Electron. Spec. Conf., 2000, pp. 1207–1211.

[3] Q. Li and P.Wolfs, “A current fed two-inductor boost converter with an integrated magnetic structure and passive lossless snubbers for photovoltaic module integrated converter applications,” IEEE Trans. Power Electron., vol. 22, no. 1, pp. 309–321, Jan. 2007.

[4] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “Power inverter topologies for photovoltaic modules—A review,” in Proc. Ind. Appl. Conf., 2002, vol. 2, pp. 782–788.

[5] C. Vartak, A. Abramovitz, and K. M. Smedley, “Analysis and design of energy regenerative snubber for transformer isolated converters,” IEEE Trans. Power Electron., vol. 29, no. 11, pp. 6030–6040, Nov. 2014.

High-Efficiency MOSFET Transformerless Inverter for Non-isolated Microinverter Applications

ABSTRACT

State-of-the-art low-power-level metal–oxide–semiconductor field-effect transistor (MOSFET)-based transformerless photovoltaic (PV) inverters can achieve high efficiency by using latest super junction MOSFETs. However, these MOSFET-based inverter topologies suffer from one or more of these drawbacks: MOSFET failure risk from body diode reverse recovery, increased conduction losses due to more devices, or low magnetics utilization. By splitting the conventional MOSFET based phase leg with an optimized inductor, this paper proposes a novel MOSFET-based phase leg configuration to minimize these drawbacks. Based on the proposed phase leg configuration, a high efficiency single-phase MOSFET transformerless inverter is presented for the PV microinverter applications. The pulsewidth modulation (PWM) modulation and circuit operation principle are then described. The common-mode and differential-mode voltage model is then presented and analyzed for circuit design. Experimental results of a 250Whardware prototype are shown to demonstrate the merits of the proposed transformerless inverter on non-isolated two-stage PV microinverter application.

 KEYWORDS: Microinverter, MOSFET inverters, photovoltaic (PV) inverter, transformerless inverter.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

image001

Fig. 1. Two-stage nonisolated PV microinverter.

CIRCUIT DIAGRAM:

image002

Fig. 2. Proposed transformerless inverter topology with (a) separated magnetic and (b) integrated magnetics.

 EXPERIMENTAL RESULTS:

image003

Fig. 3. Output voltage and current waveforms.

image004

Fig. 4. PWM gate signals waveforms.

image005

Fig. 5. Inverter splitting inductor current waveform.

image006

Fig. 6. Waveforms of voltage between grid ground and DC ground (VEG ).

CONCLUSION

This paper proposes a MOSFET transformerless inverter with a novel MOSFET-based phase leg, which achieves:

1) high efficiency by using super junction MOSFETs and SiC diodes;

2) minimized risks from the MOSFET phase leg by splitting the MOSFET phase leg with optimized inductor and minimizing the di/dt from MOSFET body diode reverse recovery;

3) high magnetics utilization compared with previous high efficiency MOSFET transformerless inverters in [21], [22], [25], which only have 50% magnetics utilization.

The proposed transformerless inverter has no dead-time requirement, simple PWM modulation for implementation, and minimized high-frequency CMissue. A 250Whardware prototype has been designed, fabricated, and tested in two-stage nonisolated microinverter application. Experimental results demonstrate that the proposed MOSFET transformerless inverter achieves 99.01% peak efficiency at full load condition and 98.8% CEC efficiency and also achieves around 98% magnetic utilization. Due to the advantages of high efficiency, low CM voltage, and improved magnetic utilization, the proposed topology is attractive for two-stage nonisolated PV microinverter applications and transformerless string inverter applications.

 REFERENCES

[1] F. Blaabjerg, Z. Chen, and S. B. Kjaer, “Power electronics as efficient interface in dispersed power generation systems,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1184–1194, Sep. 2004.

[2] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of singlephase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind. Appl., vol. 41, no. 5, p. 1292, Sep. 2005.

[3] Q. Li and P. Wolfs, “A review of the single phase photovoltaic module integrated converter topologies with three different dc link configurations,” IEEE Trans. Power Electron., vol. 23, no. 3, pp. 1320–1333, May 2008.

[4] Y. Xue, L. Chang, S. B. Kjaer, 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, 2004.

[5] W. Yu, J. S. Lai, H. Qian, and C. Hutchens, “High-efficiency MOSFET inverter with H6-type configuration for photovoltaic non-isolated AC-module applications,” IEEE Trans. Power Electron., vol. 56, no. 4, pp. 1253–1260, Apr. 2011.