5. Conclusion

In this chapter, a general model, which is modified from a conventional control structure diagram, has been introduced to analyze the harmonic generation process caused by singlephase PV inverter. The causes of the harmonics have been identified. A series of odd harmonics in the output current on the DC-link capacitor are generated by the double-line frequency voltage ripple. In this chapter, a nonlinear, time-varying model and its closed-form solution were provided. The relationship between the amplitude of the harmonics and the DC-link voltage ripples has been presented. The proposed solutions are proved by both experimental and simulation results. It is a tool for evaluating the power-quality issues in grid-connected inverter systems. The designers can also use it to consider the tradeoff between the size of the DC-link capacitor and the output harmonics in the output current.
