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Splitting of a dc voltage source with two capacitors has been the approach in generating 5-level output voltage with single- and three-phase full-bridge circuits and added bidirectional switch. Associated with this configuration is the problem of voltage imbalance between the splitting capacitors. In addition, the inverter output voltage magnitude is obviously limited to the value of the split input voltage source. Presented in this paper is a unit topology for single-phase 5-level multilevel inverter, MLI. It simply consists of a full-bridge circuit, a capacitor, charge-discharge unit and a dc source. The charge-discharge unit with the capacitor is the interface between the fullbridge and the dc source. The proposed unit cell can generate a 5-level output voltage waveform whose peak value is twice the input voltage value. For higher output voltage level, a cascaded structure of the developed unit cell is presented. Comparing the proposed inverter with CHB inverter and some recent developed MLI topologies, it is found that the proposed inverter configuration generates higher output voltage value, at reduced component-count, than other topologies, for a specified number of dc input voltages. For two cascaded modules, simulation and experimental verifications are carried out on the proposed inverter topology for an R-L load. [ABSTRACT FROM AUTHOR]

This work proposes a switching technique for cascaded H-Bridge (CHB) cells. Single carrier Sinusoidal PWM (SCSPWM) scheme is employed in the generation of the gating signals. A sequential switching and base PWM circulation schemes are presented for this fundamental cascaded multilevel inverter topology. With these proposed concepts, it is now possible to generate equal average switching signal patterns in all the constituting power semiconductor switches. This results in equal switching loss dissipation and equal power sharing in CHB multilevel inverter modules; and therefore technically modularizes the cascaded system. A 4-cell cascaded structure has been used to exemplify the proposed switching technique. Outlines with switching functions are given for the proposed modulation strategy. For a modulation index of 0.9, a THD value of 14.62% has been achieved in the output voltage waveform of the exemplanary 4-cell cascaded configuration. Verification of the performance of the proposed control technique is done through simulations and experiments. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of a new single-phase hybrid rectifier with high power factor (PF) and low harmonic distortion current. The proposed rectifier structure is composed of an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of shaping the input line current waveform, assuring high PF and low total harmonic distortion (THD). The power rating of the switched converter is less than 50% of the total output power; assuring reliability in the proposed hybrid rectifier. A pulse width modulation (PWM) control strategy was developed, imposing quasi-sinusoidal line input current waveform and limiting the switched converter power contribution. It was found that the line input current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, and simulated results are also presented in the paper. [ABSTRACT FROM AUTHOR]

The conventional five-level diode-clamped inverter suffers from the problem of many active power switches when extended to multiphase system. As a consequence, increasing number of gate drive circuits are required; resulting in complex system circuitry. This paper presents the fundamentals of a multiphase, neutral point clamped multilevel inverter configuration capable of reducing the number of active power switches in the conventional topology for multiphase system. The proposed multilevel inverter configuration generates five line-to-line voltage levels for multiphase systems. From the generalized model, an exemplary 5-phase, 5-level line-line NPC inverter supplying an RL load is considered. The operational and modulation principles and the switching patterns are outlined. The THD, as a performance index, of the line voltage output waveform of the proposed 5-phase, 5-level line-line NPC inverter is similar to that of the corresponding well-known conventional 5-phase, NPC diode-clamped inverter. The proposed inverter achieves this with fewer power circuit components and simplicity. The validity of the proposed multilevel inverter is verified through simulations and experimental results. [ABSTRACT FROM AUTHOR]

This paper describes a new power conversion circuit topology for single-phase DC-AC boost converter, based on the dc-dc boost converter. It comprises an H-bridge, fed from a single input dc source through a boosting inductor. Change of load current flow is achieved with four current-steering diodes. The proposed boost inverter configuration performs single stage power conversion, which minimizes switching losses and attains higher efficiency as compared to the conventional boost inverter. The steady-state operating principle of the power configuration and control strategy are described. A multi-loop structure controller Is used to ensure a high dynamic performance. Computer simulations demonstrate the feasibility of the proposed boost in verier. [ABSTRACT FROM AUTHOR]