Novel Family of Single-Stage Buck-Boost Inverters Based on Unfolding Circuit

ABSTRACT:

This paper describes a novel family of single-phase single-stage buck-boost inverters using output unfolding circuits. Operation principles, component design guidelines along with modulation techniques are presented and discussed. The simulation results confirm all theoretical statements. Experimental setup of the most promising solution is assembled and tested, where the efficiency for different operation modes is analyzed. Finally, the pros and cons along with applications of the proposed solutions are discussed in the conclusions.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Family of the single-phase single-stage buck-boost inverters with unfolding circuits: single-inductor unfolding buck-boost inverter (a), tappedinductor unfolding buck-boost inverter (b), single-inductor twisted unfolding buck-boost inverter (c).

EXPECTED SIMULATION RESULTS:

Fig. 2..Simulation results of proposed circuits for boost case: the output voltage and the inductor`s current ((a) for circuit in Fig. 2a, (d) for circuit in Fig. 2b, (g) for circuit in Fig. 2c); the input voltage and the input current ((b) for circuit in Fig. 2a, (e) for circuit in Fig. 2b, (h) for circuit in Fig. 2c ); ripples of the output voltage and of the inductor`s current ((c) for circuit in Fig. 2a, (f) for circuit in Fig. 2b, (e) for circuit in Fig. 2c).

Fig. 3. Simulation results of proposed circuits for buck case: the output voltage and the inductor`s current ((a) for circuit in Fig. 2a, (d) for circuit in Fig. 2b, (g) for circuit in Fig. 2c); the input voltage and the input current ((b) for circuit in Fig. 2a, (e) for circuit in Fig. 2b, (h) for circuit in Fig. 2c); ripples of the output voltage and of the inductor`s current ((c) for circuit in Fig. 2a, (f) for circuit in Fig. 2b, (e) for circuit in Fig. 2c.

  

CONCLUSION:

This paper has presented a novel family of buck-boost inverters using output unfolding circuit. Component design guidelines along with modulation techniques are given. Simulation and experimental results confirmed the theoretical analysis. It is demonstrated that the main advantage of these solutions is the reduced size of passive elements in a wide range of input voltage regulation. It is achieved due to the direct dc to ac energy conversion without any dc-link stage. Despite the increased amount of semiconductors, the overall efficiency can be very high because only two semiconductors are involved in high switching performance in any period of operation. The solutions proposed can be recommended for PV applications where high power corresponds to high voltage. In advance, it gives reduced EMI compared to any other competitive solutions. At the same time, a continuous input current is achieved. The proposed modifications of the buck-boost inverters provide high selection flexibility. The buck-boost inverter with a tap-inductor and output unfolding circuit may provide very high step-up solutions. Another valuable advantage is the common voltage shape, which contains no high switching frequency components. As a result, leakage current problem does not exist for PV application.

 

REFERENCES:

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  • Morsy, P. Enjeti, “Comparison of Active Power Decoupling Methods for High-Power-Density Single-Phase Inverters Using Wide- Bandgap FETs for GoogleLittle Box Challenge”, in IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol. 4, N 3, 2016, pp. 790–798.
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