Single‐phase ac–dc–ac topology for grid overvoltage and voltage harmonic mitigation

Abstract

A single-phase ac-dc-ac topology to improve power quality is proposed in this study. This configuration is obtained from the addition of a floating capacitor H-bridge converter on the grid side of the conventional ac-dc-ac three-leg topology. The role of the structure is not only to ensure regulated load voltage with fixed amplitude and frequency, grid current with low harmonic content and unitary power factor, but also to mitigate fundamental overvoltage and voltage harmonics at the grid. As a consequence, the proposed topology is suitable to operate as unified power quality compensator or uninterrupted power supply. It does not use isolation transformer and is capable of generating multilevel input voltages due to the cascaded H-bridge. The operation with asymmetrical dc-link voltages is considered to increase the number of voltage levels and reduce the harmonic content of the generated input voltages. Two pulse-width modulation techniques and a control system are developed to regulate the dc-link voltages and to decrease the harmonic distortion (HD), lowering the switching stress and also the power losses. The proposed configuration is compared with the conventional one with respect to HD and semiconductor losses. Simulated and experimental results are presented for validation purposes.

Open-Circuit Fault Analysis and Modeling for Power Converter Based on Single Arm Model

“…Practical power converters usually include several arms with the same structure, such as AC -DC-AC converter, which includes rectifier, DC-link and inverter. The rectifier and inverter consist of several identical arms, the DC-link is made up of several support capacitances [25][26][27]. The rectifier is connected to the power grid, which translates AC into DC.…”

Single‐phase universal active power filter based on ac–dc–ac converter with eight controlled switches

“…The proposed topology named here 5L-D (i.e. five legs, from which one leg with diodes) is derived from the topologies discussed in [23][24][25], where a converter with ten controlled switches is used. In [24], two dc-link buses are used, making the control strategy complex.…”

“…five legs, from which one leg with diodes) is derived from the topologies discussed in [23][24][25], where a converter with ten controlled switches is used. In [24], two dc-link buses are used, making the control strategy complex. When comparing the proposed 5L-D topology with the configuration presented in [25], a similarity is perceived in its structure, since the 5L-D topology replaces one of the legs with switches of the configuration presented in [25] by a leg with diodes.…”