Virtual Quadrature Source-Based Sinusoidal Modulation Applied to High-Frequency Link Converter Enabling Arbitrary Direct AC-AC Power Conversion

Most mature converters topologies for ac power conversion are inverter types, which require relatively short lifetime electrolytic capacitors. The cost, size, and weight of the converter are thus limited. While alternative solutions based on the single-phase direct ac-ac topologies are subject to zero crossing constraints, which prevent them from replacing the inverter with low reliability. In this paper, a novel virtual quadrature source-based sinusoidal modulation approach is proposed. Also, improved single-phase-based direct ac-ac topologies are derived based on the high-frequency link concept. As a result, ac voltage output with arbitrary amplitude, phase, and frequency can be synthesized only using the single-phase-based topologies. This feature eventually enables the converters to perform functions such as power line conditioning and electrical ac motor drives. Since no large dc link electrolytic capacitor is required, system reliability can be enhanced. Furthermore, the cost and the size are reduced. The proposed approach and the circuits are presented and analyzed in detail. Both simulation and experimental results show the effectiveness of the proposed concept and the converters when applying to power line conditioning and electrical ac motor drive applications.