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Supplying 25 kV, 50 Hz railway systems is a challenging task due to the load characteristics of those systems. Hence, several approaches are developed to improve their grid integration with the static frequency converter based substations. However, this supply system can be further refined by the application of a dc grid. Hence, this paper presents and discusses one possible approach to enhance the...
This paper compares several multilevel topologies (3L-NPC, 3L-TNPC, 5L-ANPC and 5L-SMC converters) as an alternative to the 2L converter for low voltage applications, using low voltage IGBT modules. The comparative evaluations are made considering figures of merit such as the total losses and their power loss distribution, the amount of devices of each converter, the maximum output power, the harmonic...
Focusing on the relevant pros provided by power conversion onboard introduction (e.g. reduction of power system weight/volume), a widespread use of power converters is foreseeable in future MVDC shipboard power systems. For conveniently exploiting the power converters capability in the marine environment, a preliminary investigation about the attainable topologies must be carried out. In this paper...
The efficiency improvement of the energy router, based on the solid state transformer, is one of the significant issues for applications in the future power networks. Power losses of switching devices play a key role about the efficiency and have a close relationship with the device, topology and control of the energy router, especially under the diversity of structure. Based on models of actual Si...
The increasing need for better performance, protection, and reliability in shipboard power distribution systems, and the increasing availability of power semiconductors is generating the potential for solid state circuit breakers to replace traditional electromechanical circuit breakers. This paper reviews various solid state circuit breaker topologies that are suitable for low and medium voltage...
The single-phase power electronic traction transformer (PETT) is a power device to realize the higher efficiency and reduction of weight in railway traction system. The single-phase cascaded H-bridge rectifiers (CHBR) are an important part of the single-phase PETT. In order to ensure its reliability, an open-circuit fault diagnosis method based on the mixed logical dynamic (MLD) model and the state...
Various topologies of multilevel inverters have been proposed as a potential replacement for cascaded multilevel inverters in high-voltage, high-power applications as they can be extended to any number of voltage levels without introducing much more complexity to the control system. This paper discussed in detail about the application of selective harmonic elimination pulse-width modulation (SHE-PWM)...
An internal paralleled active neutral point clamped converter (IP-ANPC) is presented in this paper. Advantages of the IP-ANPC converter include modularity, reliability and efficiency improvement, capability of interleaving, and better utilization of wide band-gap (WBG) devices. To simplify the operation of the IP-ANPC converter and provide an easy interleaving solution, a logic-based flying capacitor...
The isolated modular DC-DC converter (IMDCC) is a new topology designed to connect high-voltage direct current (HVDC) lines with different voltage levels, which ties two DC grids by using two modular multilevel converters (MMCs) via a medium-frequency transformer. Due to the large value of capacitance in the IMDCC, proper precharge strategies before the start-up are significant for the safety and...
In this paper, the conventional three-level diode-neutral-point-clamping (3L-DNPC) inverter is deeply investigated from the view of power loss. It is concluded that the conventional 3L-DNPC inverter has high zero-vector conduction loss due to clamping Diode+ IGBT structure's high on-state voltage, high clamping diode reverse recovery loss and so on. Therefore, the clamping diodes are most deeply related...
The latest trend in solar inverter application is to increase DC link voltage to 1500VDC for high power output. This paper describes a design concept of NPC1 power stack for 1500VDC megawatt level solar inverter. This stack uses three latest half-bridge IGBT modules with highest power density and operation junction temperature, which enable realization of power level beyond 1MW without paralleling...
This paper proposes a modified topology of modular multilevel converter (MMC) to accelerate the DC fault ride-through speed. The modified topology mainly consists of a half bridge sub-module (HBSM) and a modified series double submodule (MSDSM). The difference between the series double submodule (SDSM) and the MSDSM is a damping resistance which is used to increase the capability of the energy dissipation...
This paper presents the design and implementation of zero-voltage-zero-current switching (ZVZCS) technology in a full bridge DC/DC converter with digital control in a 20 kW multi-functional arc welding machine application. A comprehensive analysis is undertaken including power stage topology design, output voltage digital control design and power loss comparison between hard switching and ZVZCS. Experimental...
This paper presents a single phase converter topology that integrates a second harmonic energy buffer. The buffer is formed by converting one branch of the converter to use half-bridge cells, similar to an MMC type design. The energy buffer allows complete elimination of the 2nd harmonic ripple from the main DC bus and reduces overall DC link capacitor size. The topology also reduces the rms current...
In this paper, a novel topology of two-level voltage-type inverter is proposed. The proposed inverter has three bridge arms while each bridge is made up of 2 thyristors, 1 IGBT and 4 diodes. Thyristors complete the phase positioning of the inverter, IGBT completes the modulation of different modulation modes such as SPWM, SVPWM, and SHPWM, and the diodes complete the commutation of the bridge arms...
Topology of the multicell multilevel inverters are one of the most promising power converter topologies being successfully commercialized in the high-power market. This paper proposes a new cascaded multicell multilevel converter with a reduced count of power switches. The proposed reduced-switch-count multilevel is formed by connecting two distinct power conversion stages through two low-frequency...
Transformerless inverters are widely employed in PV grid-tied inverter due to their capability of reducing power losses and enhancing the system efficiency. Several multilevel transformerless topologies are investigated to increase power quality and system efficiency. Wide bandgap power devices such as SiC MOSFETs can increase the system performance and reduce the total losses due to their superior...
The purpose of this paper is to estimate the efficiency of the inverter circuits used for the Photovoltaic (PV) systems. The analysis of a power electronics converter with the SPICE during the steady-state operation takes a long time and the results may not be obtained accurately due to convergence problem in the solver. The MATLAB package program is widely preferred to analyze the power electronics...
This paper presents the integration of the photovoltaic panels which are modeled in the Matlab/Simulink to the smart grid using a 6-switched 3-level inverter. The system generates electricity by photovoltaic panels and feed load via 6-switched 3-level inverter. To reduce harmonics in the system and increase the quality of the generated signal, 6-switched 3-level inverter, which is contain an alternative...
Many new cascaded multilevel inverter (MLI) topologies have recently been proposed and published in the literature. All proposed topologies demand significant amount of semiconductor components and input dc supplies, which is considered the main drawback for the implementation of three phase cascaded MLIs. This paper proposes a new generalized concept that could be employed within any existing cascaded...
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