A Combined Multipulse-Multilevel Inverter Suitable For High Power Applications

Abstract

Abstract-Power electronic devices are finding increased applications in the transformation of electrical energy into useful forms, especially at higher power levels. The recent trend in power electronic converters is to switch the power semiconductor devices in power modulators at increased frequencies with a view to minimize harmonics, enhance power quality and regulate the output voltage. This paper is aimed to present the design of high power inverter topology capable of producing a near sinusoidal ac voltage with minimal harmonic distortion which enables its use in high power applications. The analytical expressions for the proposed inverter output voltages using Fourier analysis have been obtained. Vector diagrams are drawn to clearly illustrate the mechanism of harmonic cancellation in the proposed multipulse-multilevel inverter topology. The complete digital simulation of the proposed VSI is performed using MATLAB/Simulink and the simulation results closely agreed with the analytical results.Index Terms-Multi-pulse inverter, Multi-level inverter, Phase shifting transformer, Total Harmonic Distortion, Voltage source inverter. I. INTRODUCTIONThe progress of a nation is assessed by its economic growth, industrial development besides technological advancements. The per capita consumption of electrical energy is treated as a measure to evaluate the overall progress. It is imperative that the existing resources are fully utilized before venturing to look for alternatives, in the present energy crisis scenario. However, it is equally important to realize the rapid depletion of energy sources and contemplate measures to augment its sustainability.The field of power electronics has witnessed tremendous development in recent times. The advent of new power controlled devices has contributed significantly to an enhanced performance of the existing power converters. The birth of innovative converter topologies has paved the way for further improving the overall power quality. It has contributed to build sophisticated utilities and enable precise control of flow of power over the transmission lines. Inverters are generally used in a host of applications that include variable speed drive, uninterruptible power supplies, flexible AC transmission systems (FACTS), high voltage dc transmission (HVDC) systems, active filters, etc., The output voltage waveforms of ideal inverters should be sinusoidal. But, the waveforms of practical inverters are non-sinusoidal and contain certain harmonics. Square wave or quasi-square wave voltages may be acceptable for low-and medium-power applications. However, low distorted sinusoidal waveforms are required for high power applications especially when they are used in power system applications.Appropriate voltage source inverter circuits have to be developed in order to integrate power converter circuits into power systems. The harmonics generated on the ac side of the power inverter circuits greatly influence the power quality of the transmission system. Hence, in the present work, an att...

Hybrid Modulation for Modular Voltage Source Inverters with Coupled Reactors

“…The idea has its roots in the well-known multipulse AC-DC converter topologies widely used in a variety of applications, including adjustable speed drives (ASD), high-voltage direct current transmission (HVDC), aircraft power systems, and renewable energy conversion systems [2][3][4][5]. The use of multipulse topologies for the DC-AC power conversion has broad coverage in the literature (see, for example, in [6][7][8][9][10][11]). The topologies proposed in [8][9][10][11] are based on the use of a transformer in an integrating circuit, which significantly increases the size of the device and is an expensive solution.…”

“…The use of multipulse topologies for the DC-AC power conversion has broad coverage in the literature (see, for example, in [6][7][8][9][10][11]). The topologies proposed in [8][9][10][11] are based on the use of a transformer in an integrating circuit, which significantly increases the size of the device and is an expensive solution. If the application does not require galvanic isolation of the DC side from the AC side, the integrated circuit can be based on coupled reactors, as proposed in [1]-a solution which greatly reduces the size and cost of the circuit.…”

“…Solutions presented in [1,[7][8][9][10][11] are focused on maximizing the achievable magnitude of output voltage, while the control of lower magnitudes is left out. The possible voltage synthesis using all allowed combinations of switch states has not been seriously addressed so far.…”

A Modified Single Phase H-Bridge Inverter for High Power Applications with Power Quality Improvement

“…Now a day, the multilevel inverter is attracting the researchers in the usage of converting dc power into ac power with reduced harmonics. That is the improved PQ is obtained with direct inter connect ability of existing grid lines without the need of any inter connection transformer [1][2][3][4]. Formerly the H-Bridge inverters were connected in series to form the symmetric cascaded multilevel inverter and all the dc sources were selected with same magnitude [5][6][7].…”

Cascading of Diode Clamped Multilevel Inverter Boosters for High Voltage Applications

“…Switching states and their transitions of three-level inverter allow to balance capacitor voltages in Diode Clamped MLI (DCMI) and Flying Capacitor MLI (FCMI), where DCMI requires less capacitor power [3] size than FCMI to achieve the same capacitor voltage swinging [5,8]. The multilevel inverter system is very promising in AC drives, when both reduced harmonic contents and high power are required [10].…”