357,795 research outputs found

    Modified half-bridge modular multilevel converter for HVDC systems with DC fault ride-through capability

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    One of the main challenges of voltage source converter based HVDC systems is DC faults. In this paper, two different modified half-bridge modular multilevel converter topologies are proposed. The proposed converters offer a fault tolerant against the most severe pole-to-pole DC faults. The converter comprises three switches or two switches and 4 diodes in each cell, which can result in less cost and losses compared to the full-bridge modular multilevel converter. Converter structure and controls are presented including the converter modulation and capacitors balancing. MATLAB/SIMULINK simulations are carried out to verify converter operation in normal and faulty conditions

    A hybrid multilevel converter for medium and high voltage applications

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    This paper investigates the suitability of the hybrid multilevel converter for medium and high voltage application. The converter operation, modulation, and capacitor voltage balancing method are described in detail. The ability of the hybrid multilevel converter to operate with different modulation indices and load power factors is investigated. It has been established that the hybrid multilevel converter is capable of operating independent of load power factor. Operation with variable modulation index increases voltage stresses on the converter switches and does not alter the fundamental voltage magnitude as in all known voltage source converter topologies. The viability of the hybrid multilevel converter for medium and high voltage applications is confirmed by simulations

    Design zero-voltage switching DC-DC buck converter

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    This report proposes an integrated, high switching frequency, zero-voltage-switching dc-dc buck converter for battery charger application. The design and analysis of dc�dc buck converter with integrated inductor is presented. The converter has been optimized to convert 12V input voltage to 5V at 1.5A maximum load current at 50MHz switching frequency. The converter has been simulated using an ORCAD 16.5 based simulation tool and result show that the switching losses using zero�voltage-switching technique is less compared to conventional buck converter

    Investigation of Fault-Tolerant Capabilities in an Advanced Three-Level Active T-Type Converter

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    A novel fault-tolerant three-level power converter topology, named advanced three-level active T-Type (A3L-ATT) converter, is introduced to increase the reliability of multilevel power converters used in safety-critical applications. This new fault-tolerant multilevel power converter is derived from the conventional T-Type converter topology. The topology has significantly improved the fault-tolerant capability under any open circuit or certain short-circuit faults in the semiconductor devices. In addition, under healthy condition, the redundant phase leg can be utilized to share overload current with other main legs, which enhances the overload capability of the converter. The conduction losses in the original outer devices can be reduced by sharing the load current with the redundant leg. Moreover, unlike other existing fault-tolerant power converters in the literature, full output voltages can be always obtained in this proposed A3L-ATT converter during fault-tolerant operation. A 13.5-kW ATT-A3L converter prototype was developed and constructed using silicon carbide MOSFETs. Simulation and experimental results were obtained to substantiate the theoretical claims of this new fault-tolerant power converter

    Cost-Effective and High-Efficiency Variable-Speed Switched Reluctance Drives With Ring-Connected Winding Configuration

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    This paper presents a novel converter topology for six-phase switched reluctance motor (SRM) drives, which reduces the number of switches and diodes by half, compared with the conventional asymmetric half-bridge converter, but needs no additional energy storage component. A dynamic model of a six-phase SRM is developed in the MATLAB/SIMULINK environment and conventional current chopping and angle position control techniques are applied to the proposed converter, demonstrating successful operation across the full speed range with modified conventional control techniques, lower converter losses, and higher system efficiency compared with the asymmetric half-bridge converter. Experimental tests comparing two versions of the proposed converter with an asymmetric half-bridge are described and verify the predictions of the simulations

    Morphing Switched-Capacitor Converters with Variable Conversion Ratio

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    High-voltage-gain and wide-input-range dc-dc converters are widely used in various electronics and industrial products such as portable devices, telecommunication, automotive, and aerospace systems. The two-stage converter is a widely adopted architecture for such applications, and it is proven to have a higher efficiency as compared with that of the single-stage converter. This paper presents a modular-cell-based morphing switched-capacitor (SC) converter for application as a front-end converter of the two-stage converter. The conversion ratio of this converter is flexible and variable and can be freely extended by increasing more SC modules. The varying conversion ratio is achieved through the morphing of the converter's structure corresponding to the amplitude of the input voltage. This converter is light and compact, and is highly efficient over a very wide range of input voltage and load conditions. Experimental work on a 25-W, 6-30-V input, 3.5-8.5-V output prototype, is performed. For a single SC module, the efficiency over the entire input voltage range is higher than 98%. Applied into the two-stage converter, the overall efficiency achievable over the entire operating range is 80% including the driver's loss

    Evaluation of a dual-T-type converter supplying an open-end winding induction machine

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    The multilevel inverter is a promising technology compared to two-level inverters in the applications of ac-drives and smart-grid applications. In this paper, a dual-T-type three-level inverters is used to drive an open-end winding induction machine. The Space-Vector Pulse-Width Modulation is selected as a good-performing control strategy to control the dual-inverter. Furthermore, an optimized method is used to select the proper switching state for the new configuration to decrease the converter losses. A comparison between the proposed configuration and the conventional diode clamped converter is made. The proposed drive system is designed and modelled by using Matlab/Simulink. It is shown that the converter can give the same hexagon, wave forms and harmonic spectrum of the five level converter. An optimized switching state selection is used to reduce the converter losses. The advantages and drawbacks of the dual-T-type configuration are discussed. In addition, the harmonic analysis and the loss calculations of the dual-T-type converter are provided and compared to the T-type three-level converter and the conventional five-level diode-clamped-converter

    A novel enhanced connection of AC/AC powertrain for HEV - modelling and simulation results

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    The paper deals with a novel enhanced connection of AC/AC powertrain for Hybrid Electric Vehicles (HEV). The substantial contribution of such a connection is the absence of 4QC auxiliary converter needed for autonomous and hybrid operational modes and its compensation by power-lesser 0x5 matrix converter. The main advantages of a simplified connection are, beside smaller auxiliary converter sizing, also possible better efficiency of the HEV powertrain. So, powertrain operation in autonomous traction accu-battery modes uses direct 0x5 configuration of traction 3x5 MxC matrix converter, and in hybrid modes of Internal Combustion Engine (ICE) and accu-battery uses besides traction 3x5 MxC matrix converter the auxiliary 0x5 matrix converter. Modeling and simulation using Matlab-Simulink environment of traction powertrain configuration in autonomous modes are presented in the paper as well as all simulation experiment result

    A Novel Cyclic Time to Digital Converter Based on Triple-Slope Interpolation and Time Amplification

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    This paper investigates a novel cyclic time-to-digital converter (TDC) which employs triple-slope analog interpolation and time amplification techniques for digitizing the time interval between the rising edges of two input signals(Start and Stop). The proposed converter will be a 9-bit cyclic time-to-digital converter that does not use delay lines in its structure. Therefore, it has a low sensitivity to temperature, power supply and process (PVT) variations. The other advantages of the proposed converter are low circuit complexity, and high accuracy compared with the time-to-digital converters that have previously been proposed. Also, this converter improves the time resolution and the dynamic range. In the same resolution, linear range and dynamic range, the proposed cyclic TDC reduces the number of circuit elements compared with the converters that have a similar circuit structure. Thus, the converter reduces the chip area, the power consumption and the figure of merit (FoM). In this converter, the integral nonlinearity (INL) and differential nonlinearity (DNL) errors are reduced. In order to evaluate the idea, the proposed time-to-digital converter is designed in TSMC 45 nm CMOS technology and simulated. Comparison of the theoretical and simulation results confirms the benefits of the proposed TDC
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