Single-phase AC-DC-AC topology for grid voltage compensation

This paper proposes a single-phase ac-dc-ac converter composed of two three-leg converters connected in series with an H-bridge on its grid side. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental overvoltage and voltage harmonics in the grid. The system model, a power flux analysis, two pulse width modulation (PWM) techniques, and techniques for balancing the dc-link voltages are given. A complete control system is also included. The proposed topology is compared with the conventional one in terms of operation range, harmonic distortions, semiconductor losses, and others characteristics. Simulation and experimental results are provided to validate the feasibility of the system under grid voltage sags and swells.