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A 1-φ hybrid nine-level inverter (H9LI) topology has been proposed in this paper. The proposed H9LI topology uses a simple phase disposition pulsewidth modulation strategy to generate nine-voltage levels in the output. The main advantage of this topology is that it has a low switch count (ten switches) compared to the existing nine-level inverter topologies. To regulate the voltage across auxiliary capacitor, two innovative control techniques are proposed, which are integrated with the inverter modulation technique itself. Hence, it does not require any extra voltage balancing circuits to maintain the voltage across the auxiliary capacitor and input dc capacitors. A major advantage of these control techniques is that they eliminate the sensing of the coupled inductor current. Another significant advantage of H9LI is that loss distribution among all the power switches is more uniform compared to existing nine-level inverters. Due to low part count and absence of extra voltage balancing circuits, the H9LI achieves higher efficiency (η ≍ 94.5%) and lower cost. Furthermore, the requirement of filter size reduces due to the presence of coupled inductor in H9LI. The proposed 1-φ grid connected H9LI is verified through MATLAB/Simulink simulations and validated through experiments on a laboratory prototype of 400-VA rating. [ABSTRACT FROM AUTHOR]

This paper presents a variable switching point predictive current control (VSP $^2$CC) for the quasi-Z-source inverter (qZSI). The proposed VSP $^2$CC aims to remove the output current error on the ac side, as well as the inductor current and capacitor voltage errors of the quasi-Z-source network on the dc side of the converter. Unlike the previously presented direct model predictive control (MPC) strategies for the qZSI, the proposed control scheme can directly apply the switching signals not only at the discrete time instants, but at any time instant within the sampling interval. Consequently, the shoot-through state can be applied for a shorter time than the sampling interval, resulting in lower output and inductor currents ripples. Experimental results based on field programmable gate array are provided to verify the effectiveness of the introduced control method. As it is shown, the proposed method leads to lower inductor current ripples and less output current total harmonic distortion when compared with the conventional direct MPC. [ABSTRACT FROM AUTHOR]

In this paper, a common grounded Z-source dc–dc converter with high voltage gain is proposed for photovoltaic (PV) applications, which require a relatively high output–input voltage conversion ratio. Compared with the traditional Z-source dc–dc converter, the proposed converter, which employs a conventional Z-source network, can obtain higher voltage gain and provide the common ground for the input and output without any additional components, which results in low cost and small size. Moreover, the proposed converter features low voltage stresses of the switch and diodes. Therefore, the efficiency and reliability of the proposed converter can be improved. The operating principle, parameters design, and comparison with other converters are analyzed. Simulation and experimental results are given to verify the aforementioned characteristics and theoretical analysis of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper proposes a new topology for an enhanced-boost Z-source inverter (ZSI) with combined two Z-impedance networks. By two Z-impedance networks and low shoot-through duty cycle, the proposed inverter produces high output voltage gain. In traditional ZSIs for high boosting voltage, a low modulation index is required; hence, under these conditions, the output voltage will have low quality with high total harmonic distortion. Compared with the conventional high-boost ZSI topologies, the proposed inverter uses shorter shoot-through duration and a larger modulation index to improve the output waveform quality. Comparison between the proposed topology and previously proposed schemes, in terms of inductor numbers, voltage and current stresses on elements, sizes of inductors and capacitors, efficiency, and switching device product (SDP) factors of diodes, is made, and the results verify the priority of the proposed topology. The operating principle of the proposed topology is analyzed in detail. Both simulation and experimental results verify the high performance of the proposed inverter. [ABSTRACT FROM PUBLISHER]