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Multilevel inverters with common-ground feature have been getting attention especially for grid-tied photovoltaic systems. These inverters have the grid neutral line connected to the negative pole of the dc bus, eliminating the common-mode leakage current which is a critical issue in grid-connected PV systems. This paper proposes a common-ground five-level transformerless inverter with a reduced switch count for solar photovoltaic applications. The proposed inverter comprises only four power switches, three diodes, two capacitors and two inductors. Moreover, only two switches operate at high-frequency, enabling the reduction of switching losses. The interleaved operation of a coupled inductor enhances the quality of the output current, as the first group of harmonic components is around twice the switching frequency. Additionally, a full dc- bus voltage utilization is provided and the reactive power capability is achieved. The paper details the operation modes, the design guidelines as well as a control and modulation strategy for the proper operation of the inverter. Finally, experimental results are obtained to validate the performance of the proposed grid-tied inverter.

In this article a new bridgeless BL buck boost power factor correction PFC converter using pulsewidth modulation PWM control is presented The introduced structure operates in a discontinuous conduction mode DCM to achieve the sinusoidal form of the input current inherently The proposed converter utilizes a simple zero voltage transition ZVT circuit in which the auxiliary switch is turned on and off under zero current switching ZCS condition and the main switches turn on and off under zero voltage switching ZVS Moreover all diodes are turned off under ZCS conditions and the reverse recovery problem is solved By reducing the number of semiconductor elements in the current flow path conduction loss is minimized Also the proposed structure utilizes only one magnetic element The above mentioned advantages along with a low total harmonic distortion THD and high efficiency are the main benefits of the proposed structure compared to previous topologies In addition unlike the BL buck converter the input current dead angle is omitted without adding any extra components Finally a 500 W 100 kHz prototype at 90 265 Vrms input and 96 V output is implemented to verify the theoretical analysis and it illustrates the efficiency of 97 35 and the input current THD is about 2 7 at 220 Vrms input voltage

Multilevel inverter demonstrates advantages over conventional topologies to meet the grid codes and standards. Compared to 3-level inverters, multilevel inverter exhibits significantly better harmonic performance, better efficiency, lower filter size, and less dv/dt and di/dt in the switches. In this regard, a modified HERIC-based topology with a 5-level modulation technique is derived from the conventional 3-level passive midpoint clamped HERIC-based topology and introduced in this paper. A circuit description and working principles of the proposed converter with simulation results, and experimental results are given to demonstrate the feasibility of the concept.

The circuit performance of conventional active neutral point-clamped (ANPC) inverter is widely accepted in many renewable energy-based applications like photovoltaic (PV) or electric vehicle grid-connected systems. This is mainly because of its excellent characteristics in terms of voltage/current stress profile of the switches, bidirectional power flow capability, and efficient operation. Nonetheless, due to its half-dc link voltage utilization in the ac output voltage, another power processing stage with additional active and passive elements is required to make its output voltage compatible with the grid when low and wide varying input dc source is available. In this paper, a novel ANPC-based five-level (ANPC5L) inverter with a single-stage boost-integrated circuit design is presented. The proposed topology is able to make the peak output voltage of the conventional ANPC5L inverter followed by a front-end bidirectional boost converter double using the same number of power switches but with less total standing voltage across semiconductors. The working principles of the proposed topology is discussed. Experimental results obtained from 1.3 kW laboratory-built prototype under the grid-connected condition are also given to support the discussion.

This paper presents a common-ground five-level transformerless inverter for solar photovoltaic (PV) applications. In the proposed inverter, the grid neutral line is directly connected to the negative pole of the dc bus eliminating the common-mode leakage current which is a critical problem in grid-connected PV systems. Moreover, the proposed inverter has only four power switches, making the first five-level common-ground topology with less than six switches found in the recent literature. In addition to low switch count, only two switches are operating in high-frequency. The operation modes, the design guidelines as well as a modulation strategy are presented. Simulation and experimental results are obtained to demonstrate the performance of the proposed inverter.

A single-phase common-ground five-level (5L) inverter with a dynamic voltage conversion gain and capability of operating in a wide input voltage range and a single-stage energy conversion configuration is presented in this article. The proposed topology requires nine active power switches and is comprised of an integrated switched-boost (SB) module connected in series to a switched-flying-capacitor (SFC) cell. Two self-balanced capacitors with a single boost inductor in the integrated SB module are employed to generate a 5L output voltage waveform with a dynamic voltage conversion gain. The current stress profile of all the active and passive elements is kept within a permissible input current range. By adopting an extra diode-capacitor-inductor network into the integrated SB module and with the utilization of the same SFC cell, the proposed topology is extended to achieve a quadratic voltage conversion gain while retaining the quality of ac voltage waveform. Theoretical analysis, closed-loop control/modulation principles, design guidance, comparative study, and relevant experimental results obtained from a 1.5-kW laboratory-built prototype are presented to ascertain the operation and feasibility of the proposed system.

H-bridge inverter is a common topology used for single-phase applications. Due to its limited voltage gain, a two-stage power conversion with a front-end dc-dc converter is usually adopted to accommodate the low dc source voltage. Recently, single-stage boost inverters are gaining significant interest due to their higher power efficiency and compactness. This paper presents a family of boost inverters with continuous dc source current. By the incorporation of merely a power switch and a boost inductor to the first leg of H-bridge, voltage-boosting and 3-level generation can be simultaneously achieved within a single-stage operation. All potential topologies using the same number of components are derived. An extension to generate five voltage levels with voltage gain enhancement is also proposed. The operation of the proposed boost inverters is thoroughly analyzed. Simulation and experimental results are presented for verification.