Cascaded single-phase, PWM multilevel inverter with boosted output voltage

Abstract

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 full-bridge 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.
 Keywords: Cascaded multilevel, Inverter, total harmonic distortion, topologies, waveform

An optimal control technique for single-phase grid-connected inverter

“…The graph in Figure (5) shows the DC voltage, the grid voltage and the synchronized grid and inverter current at the PCC. Figure (6) shows the grid and inverter output voltage, the synchronized grid voltage and current and the synchronized inverter voltage and currents. Figure (7) show the harmonic analysis conducted on the PCC current of the inverter from which %THD was obtained.…”

“…DPWM as a control mechanism for GCI has an advantage of its ability to reduce the low order harmonic components of sinusoidal signals [4]. This is achievable by comparing a triangular carrier signal having high frequency with a low frequency sinusoidal reference signal, the point intersection between the signal determines the switching pulses that drive the gates of the VSI [6]. Research efforts have been made on the viability of integrating PVS with the utility grid.…”