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The global energy consumption is increasing day by day. This increased energy demand can only be fulfilled through large-scale renewable energy integration. This article presents the mathematical modeling, control, and integration of a bio-fuel prime mover fed self-excited induction generator (SEIG) for medium voltage direct current (MVDC) ship power system. A three-phase current controlled voltage source inverter (VSI) working as a static synchronous compensator (STATCOM) injects compensating currents at the point of common coupling (PCC) for harmonic elimination and regulation of the generated voltage under varying load. The VSI is connected at the PCC through a three-phase zig-zag/star transformer which reduces the voltage stress at the DC link. An indirect current technique based controller is used to generate gating pulses for the STATCOM. The MVDC load zone is modeled as an integral sliding mode controlled DC-DC converter feeding ship service loads in shipboard system. Hardware realization of the proposed system has been implemented with 3.7kW induction generator. [ABSTRACT FROM AUTHOR]

This study presents a new multilevel inverter (MLI) with reduced devices, for low/medium- and high-voltage applications. The proposed MLI is evolved from existing cross-connected source-based multilevel inverter (CCS-MLI), results in reduced switches, driver circuits, diodes, and DC voltage sources when compared with the classical CHB, CCS-MLI, and other MLIs. Owing to reduced device numbers, the complexity, size, cost, and maintenance of the proposed topology are greatly reduced. The detailed analysis and working of the proposed topology is presented along with its comparison with classical, CCS-MLI, and other MLIs. Different algorithms are presented for selecting appropriate magnitudes of DC voltage sources to generate different voltage levels in the output. The proposed MLI is suitable for grid integration of renewable energy sources. The concept is presented through modelling and simulation in MATLAB/Simulation environment and validated through real-time simulator OPAL-RT (OP-4500). [ABSTRACT FROM AUTHOR]

This paper presents a multilevel inverter that has been conceptualized to reduce component count, particularly for a large number of output levels. It comprises floating input dc sources alternately connected in opposite polarities with one another through power switches. Each input dc level appears in the stepped load voltage either individually or in additive combinations with other input levels. This approach results in reduced number of power switches as compared to classical topologies. The working principle of the proposed topology is demonstrated with the help of a single-phase five-level inverter. The topology is investigated through simulations and validated experimentally on a laboratory prototype. An exhaustive comparison of the proposed topology is made against the classical cascaded H-bridge topology. [ABSTRACT FROM PUBLISHER]

As multilevel inverters are gaining increasing importance, newer topologies are being proposed to reduce part count for large number of levels in output voltage. A simplified five-level inverter has been recently reported in the literature to reduce component count. The topology comprises of floating input DC sources connected in opposite polarities through power switches. The structure requires lesser active switches as compared with conventional cascaded H-bridge topology with much reduced switching losses. Available literature present generalisation of the topology with symmetrical sources, but no investigations are made for equal load sharing and asymmetrical configurations. This study presents a comprehensive analysis of the aforementioned topology, referred to as cross-connected sources-based multilevel inverter (CCS-MLI). The topology is analysed for both symmetric and asymmetric source configurations. Also, a new algorithm for asymmetric source configuration suitable for CCS-MLI is proposed. A control scheme is also proposed for equal load sharing in five-level topology. Investigations are made for possibility of equal load sharing in higher level structures and fundamental frequency switching of switches bearing higher voltage stresses. Various concepts are verified with simulations and experimental studies. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a simple neutral point potential (NPP) regulator for a three-level diode-clamped inverter employing a sine-triangle regulator in conjunction with a closed-loop controller with reduced switching losses. The regulator principle is based on adding a continuous variable offset voltage which regulates the midpoint potential of the dc bus. The novelty of the proposed NPP regulator is in the determination of the magnitude of variable offset voltage based upon the average value, peak-to-peak amplitude, total harmonic distortions, and third harmonic content in NPP. Aside from maintaining dc-bus voltage balance, the proposed regulator leads to a significant reduction in the voltage distortion at the NP, resulting in the reduction of the required dc-bus capacitance. It also reduces the switching losses of the inverter by inserting the “no-switching” zone within each half cycle of the fundamental voltage wave. Analytical, computer simulation, and experimental results verifying the approach are presented in this paper for various load power factor angles. [ABSTRACT FROM AUTHOR]

Abstract: Suitable integration of more than one energy sources is an interesting and challenging task that attracts attention of the researchers. Integration of several energy sources profoundly depends on the power electronic converters which interface multiple energy sources having different V–I characteristics. Therefore, suitable integration and better utilization of energy source demands, well designed and efficient interfacing circuitry. In this paper, a non isolated multiple source DC/DC converter (MSC) is proposed. The generation of MSC using pulsating source cells as a building block has been discussed briefly. The proposed converter is proficient for energy diversification from renewable and storage energy sources individually or simultaneously. It has the capability to operate either in buck, boost or buck–boost mode of operation with possibility of bidirectional power flow. It offers simplicity in structure with inherent bypass circuit, flexibility in control scheme and reliability in operation. In addition, a power management control algorithm for proposed converter has also been discussed. The proposed concept has been investigated through detailed device level simulation using MATLAB/Simulink environment. Experimental implementation and validation have been carried out on a low power prototype using digital signal processor (DSP) TMS320F2812. [Copyright &y& Elsevier]

In this study, a multiple-input non-isolated DC/DC converter topology is presented. The proposed multiple-input DC/ DC converter is proficient for energy diversification from renewable and storage energy sources individually or simultaneously. It can be operated in buck, boost and buck-boost modes of operation with the capability of bidirectional power flow to achieve desired voltage level on either side. The development of small-signal modelling based on state-space averaging has been discussed. In addition, a power management control scheme for the proposed converter has also been presented. The proposed concept has been investigated through simulation using the MATLAB/Simulink environment and validated experimentally on a laboratory prototype using dSPACE 1103 real time digital con [ABSTRACT FROM AUTHOR]

Abstract: Recently multilevel inverters are gaining popularity due to reduced voltage stress across power switches and low total harmonic distortion (THD) output voltage waveform. However, device count increases with increased voltage levels. This paper presents a novel multilevel topology which is capable of obtaining all additive and subtractive combinations of input DC levels in the output waveform. Though all such levels can be obtained using the proposed topology, the actual number of levels depends on the DC source arrangement. A comparison is made between proposed topology and the classical multilevel topologies on the basis of device count and number of levels in the output voltage waveform. A detailed study of the proposed topology is presented through the example of a nine-level inverter. Appropriate modulation scheme is also presented. The proposed concept is analyzed through simulation studies and verified experimentally. [Copyright &y& Elsevier]

Summary: Medium voltage direct current (MVDC) is an emerging trend in ship power system to cater the growing power demand in modern navy applications. Marine diesel oil (MDO) is the primary fuel in the shipping sector. However, with rising oil prices and harmful emissions, there is a greater need than ever for ship operators to consider clean power generating options. Keeping this in mind, this paper aims to present a renewable energy solution through development and integration of a three‐phase self‐excited induction generator (SEIG)–based renewable biofuel generator in MVDC ship power system. A three‐phase current controlled voltage source inverter (VSI) working as a static synchronous compensator (STATCOM) performs multiple tasks of harmonic elimination and regulation of the generated voltage under varying load. Gating pulses to the STATCOM switches are generated using indirect current theory‐based controller. An integral sliding mode‐controlled direct current to direct current (DC‐DC) converter feeding ship service loads in MVDC shipboard system has taken as a nonlinear load. A laboratory prototype of the complete system has developed to validate the concept. [ABSTRACT FROM AUTHOR]