A New Single-Stage Transformer less Inverter for Photovoltaic Applications

Abstract

In this paper a new single-stage transformer less inverter for photovoltaic (PV) application is proposed. Typical PV systems have multi-stage topology in order to perform different functions. These multi-stage inverters suffer from low efficiency and high components count. The proposed inverter is a combination of boost converter and half bridge inverter which can handle voltage boosting as well as feeding ac current to the grid in one stage. The introduced converter is transformer less which increases the overall efficiency and decreases cost, size and weight of the system. This topology has several desirable features like low switching losses, low total harmonic distortion (THD) and simple control technique. In this paper, operation principle, theoretical analysis and design of the proposed topology are discussed. Also, simulation and experimental results of a l00W inverter are presented to confirm the validity of theoretical analysis.

Keywords

1.      Photovoltaic inverter

2.      Transformer less inverter

3.      Single-stage inverter

Schematic Diagram:

Fig. 1. Schematic of proposed single-stage transfonnerless inverter.

Expected Simulation Results:

Fig. 2. Simulation results of (a) current of inductors at the peak of output voltage, and (b) voltage and current of switch S ,.

Fig. 3. Simulated waveforms of (a) gate drive signals, and (b) output voltage at fullioad .

Conclusion

In this paper a new single-stage inverter which is suitable for PV application is proposed. Due to omitting galvanic isolation, the cost, size and weight of the system is reduced. Simple structure, low switching losses and easy control scheme are the main features of the presented inverter. The operation principle is disused and the inverter design is presented. Also the control scheme is presented. Simulation and experimental results demonstrates the high performance of the proposed system. Due to boosting ability and achieving low-voltage THD, this topology is suitable for PV grid connected systems.

References

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