Multilevel inverters (MLIs) are being used in wide range of power electronics applications. These converters that are attracted a lot of attentions during recent years have different topologies with similar basic concept. This paper presents five main submodules (SMs) that are used as the basic structures of MLIs. The paper reviews the common multilevel inverter topologies with the structural point of view. The topologies are divided to main SMs to show conventional MLIs configuration and future topologies that can be created from the main SMs. The comparative study on topologies is investigated with details. The MLIs are categorized and investigated with due attention to some indexes such as the number of components, the ability to create inherent negative voltage, working in regeneration mode and using single DC source.

This paper presents a novel high step-up Multi-Level Inverter (MLI) with a single DC source based on switched-capacitor modules in which it is suitable for the renewable energy applications with low voltage DC source. The proposed topology has the ability of the voltage self-balancing for the capacitors without any external or closed-loop circuits. Another merit of the proposed structure is the producing of bipolar staircase waveform without any end-side Full-bridge in which it reduces the voltage stress on components, remarkably. The circuit topology and its operation principle, capacitances calculations and comparison of the proposed circuit with other well-known single source MLIs are discussed in details. Finally, a 21-level prototype of the proposed inverter with 32 volts input voltage and high gain 10 by using four modules was evaluated by both simulation and experimental tests.

The paper presents a new transformer‐less step‐up multilevel inverter structure with a single DC source. The concept was based on cascaded connection of bipolar T‐type 5‐level modules. Proper charging and discharging of capacitors across the load in prearranged time durations would make a nearly sinusoidal staircase voltage. The output voltage amplitude was several times greater than the DC input depending on the number of modules and charging mode of the capacitors. Multiplying the input voltage, self‐balancing, generating bipolar voltage waveform, easy circuit expansion and considerably low THD (Total Harmonic Distortion) were found to be the advantages of the proposed topology. The paper also adds operating principle, simulation and experimental results of a 29‐level prototype based on the presented inverter structure.

This paper presented a new structure for the grid-connected multi-level inverters (MLI) circuit with the ability of the cascaded connection. The proposed inverter is capable of transformer-less connection of distributed generation resources to the network. The control system manages the power injection to the grid by minimizing the output current harmonics as well as exchanging reactive power with the grid. The self-balancing state of the capacitors’ voltage is occurred only with the switching technique without any measurement sensors. An Enhanced Phase Locked Loop (EPLL) and a proportional resonant (PR) controller are employed for the proposed asymmetric MLI. An important feature of the proposed inverter is the ability of stable performance and fast dynamics of the control system to the changes of the reference values. Simulation and experimental results are presented in order to validate the performance accuracy of the proposed MLI.

This paper proposes a pulsed power supply topology based on the combination of capacitor-diode voltage multiplier and resonant circuit. It generates high output voltage pulses with low ac input voltage using power electronics switches. Based on the type of application, simple or combined mode pulses can be created by proposed topology. The combined mode pulse (wide pulses combined with narrow pulses) generation can be a very good alternative strategy for food sterilization, which can reduce the amount of consumed power and avoid side effects of wide pulses used in the food treatment process. Simulation and experimental results are presented to verify the proposed topology.

This paper proposes a new developed switched-capacitor converter to achieve high voltage pulses with adjustable voltage level and frequency. The proposed topology generates repetitive high voltage pulses by using low voltage power supply with reduced number of components including power semiconductors and capacitor. Therefore, a converter based on switched capacitor units with high voltage gain and high efficiency can be achieved. Operation principles and design steps of the converter as well as comparative study with conventional converters are described in this paper. Finally, Simulation and experimental results of 2-stage structure of the proposed circuit validate the operation principles and features of this topology.