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Herein, we propose a novel three-phase quasi-Z-source inverter with a high voltage transmission ratio to address challenges such as high switching loss and sizeable magnetic components in the basic quasi-Z-source inverter. The proposed circuit topology, control strategy, and related analysis are presented. The circuit topology of the inverter comprises a quasi-Z-source network with an integrated magnetic inductor, an active clamp circuit, a three-phase inverter bridge, and an output LC filter, all of which are connected in series. An improved 12-sector space vector modulation scheme is proposed based on the root-mean-square value of the voltage and the instantaneous value of the current. Furthermore, analyses of the inverter voltage transmission ratio, resonant process, and parametric design guidelines for integrated magnetic inductor and zero-voltage switching conditions are presented. Experimental results on a 1-kVA prototype inverter demonstrate that the proposed inverter exhibits a higher transmission ratio and efficiency than existing inverters; thus, the proposed inverter would have broad prospects in low-voltage DC-AC applications. [ABSTRACT FROM AUTHOR]

A current-source single-stage multi-input high-frequency-link grid-connected inverter and a three-mode one-cycle control strategy are proposed and deeply investigated in this paper. The inverter contains multiple current-source inverting units, a multi-input high-frequency transformer, and a cycloconverter. It achieves single-stage power conversion and high-frequency galvanic isolation with a simple circuit structure. The control strategy adds a by-pass switch to the energy storage inductor. It has energy-storing, energy-releasing, and three by-pass operation modes in a low frequency cycle. Through calculating the energy-releasing duty cycle in real time, the magnetic saturation problem of current-source inverters is solved and the output waveform quality is greatly improved. Soft-switching of the converter, a transfer function block diagram, and the design of the main circuit parameters are achieved. The simulation of a three-input inverter and experiment on a two-input inverter verify the feasibility and advancement of the proposed circuit topology and control strategy. [ABSTRACT FROM AUTHOR]

A voltage-fed single-stage multi-input inverter for hybrid wind/photovoltaic power generation system is proposed, and its circuit topology, control strategy, and derivation of multiple duty ratios are studied in detail. Also, the methods to avoid turn-off voltage spike of selection switches and magnetic saturation of line-frequency (LF) transformer are fully investigated. The maximum power point tracking outer loop/grid-connected current (GCC) inner-loop control strategy decomposes the GCC according to the maximum power provided by each input source, to ensure the power distribution of each source and the direct control of GCC. By adjusting the drive signals of selection switches, the feedback path for inductor current is ensured and the voltage spike is intrinsically eliminated. The introduction of the DC bias correction loop for GCC restrains the magnetic saturation of the LF transformer. Simulation and experimental results of the designed 3 kW laboratory prototype verify the feasibility and validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]