3,901 research outputs found

    Multilevel Converters: An Enabling Technology for High-Power Applications

    Get PDF
    | Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.Ministerio de Ciencia y TecnologĂ­a DPI2001-3089Ministerio de EduaciĂłn y Ciencia d TEC2006-0386

    Input current shaped ac-to-dc converters

    Get PDF
    Input current shaping techniques for ac-to-dc converters were investigated. Input frequencies much higher than normal, up to 20 kHz were emphasized. Several methods of shaping the input current waveform in ac-to-dc converters were reviewed. The simplest method is the LC filter following the rectifier. The next simplest method is the resistor emulation approach in which the inductor size is determined by the converter switching frequency and not by the line input frequency. Other methods require complicated switch drive algorithms to construct the input current waveshape. For a high-frequency line input, on the order of 20 kHz, the simple LC cannot be discarded so peremptorily, since the inductor size can be compared with that for the resistor emulation method. In fact, since a dc regulator will normally be required after the filter anyway, the total component count is almost the same as for the resistor emulation method, in which the filter is effectively incorporated into the regulator

    Integrated series active filter for aerospace flight control surface actuation

    Get PDF
    The paper investigates integrated series active filters to satisfy aircraft power quality benchmarks and underlying design compromises. Advantages include reduced component count and retrofitting capability. Further insights into the merits of the proposed solution are included, along with representative results from a prototype system

    A back to back multilevel converter for driving low inductance brushless AC machines

    Get PDF
    Traditionally, multilevel converters are utilised in medium voltage applications, allowing the DC-link voltage to exceed the switch maximum blocking voltage. Here, their application to control high- efficiency brushless permanent magnet synchronous machines exhibiting low phase inductance is explored, the relative advantages being shown to include reduced current ripple and improved harmonic spectrum. A cost benefit analysis is included along with experimental results from a prototype 5-level back-to-back converter

    Comparison of single-phase matrix converter and H-bridge converter for radio frequency induction heating

    Get PDF
    This paper compares the newly developed single-phase matrix converter and the more conventional H- bridge converter for radio frequency induction heating. Both the converters exhibit unity power factor, very low total harmonic distortion at the utility supply interface, good controllability under soft switching condition for a wide range of power, and high efficiencies, whilst still having simple structures. A novel switching control pattern has been proposed for the matrix converter in order to maintain the comparable performance to the H-bridge converter. Simulation and experimental results for both converters are presented. Comparisons between two converters have confirmed the excellent performance of the proposed matrix converter

    Multi-Frequency Modulation and Control for DC/AC and AC/DC Resonant Converters

    Get PDF
    Harmonic content is inherent in switched-mode power supplies. Since the undesired harmonics interfere with the operation of other sensitive electronics, the reduction of harmonic content is essential for power electronics design. Conventional approaches to attenuate the harmonic content include passive/active filter and wave-shaping in modulation. However, those approaches are not suitable for resonant converters due to bulky passive volumes and excessive switching losses. This dissertation focuses on eliminating the undesired harmonics from generation by intelligently manipulating the spectrum of switching waveforms, considering practical needs for functionality.To generate multiple ac outputs while eliminating the low-order harmonics from a single inverter, a multi-frequency programmed pulse width modulation is investigated. The proposed modulation schemes enable multi-frequency generation and independent output regulation. In this method, the fundamental and certain harmonics are independently controlled for each of the outputs, allowing individual power regulations. Also, undesired harmonics in between output frequencies are easily eliminated from generation, which prevents potential hazards caused by the harmonic content and bulky filters. Finally, the proposed modulation schemes are applicable to a variety of DC/AC topologies.Two applications of dc/ac resonant inverters, i.e. an electrosurgical generator and a dual-mode WPT transmitter, are demonstrated using the proposed MFPWM schemes. From the experimental results of two hardware prototypes, the MFPWM alleviates the challenges of designing a complicated passive filter for the low-order harmonics. In addition, the MFPWM facilitates combines functionalities using less hardware compared to the state-of-the-art. The prototypes demonstrate a comparable efficiency while achieving multiple ac outputs using a single inverter.To overcome the low-efficiency, low power-density problems in conventional wireless fast charging, a multi-level switched-capacitor ac/dc rectifier is investigated. This new WPT receiver takes advantage of a high power-density switched-capacitor circuit, the low harmonic content of the multilevel MFPWMs, and output regulation ability to improve the system efficiency. A detailed topology evaluation regarding the regulation scheme, system efficiency, current THD and volume estimation is demonstrated, and experimental results from a 20 W prototype prove that the multi-level switched-capacitor rectifier is an excellent candidate for high-efficiency, high power density design of wireless fast charging receiver

    A System-based Modeling and Simulation of a Floating Production Storage and Offloading (FPSO) Electric Power Systems and Core Loss Analysis of Synchronous Generator and Induction Motor

    Get PDF
    In this dissertation, a system based modeling and simulation were investigated for FPSO power system components and a few experimental results were evaluated to determine core losses in a synchronous generator under non-sinusoidal current. Modeling and simulation results are presented to predict both the utility and the motor side challenges caused by different harmonic distortion levels. VFD was modeled as a rectifier and an inverter isolated by the DC link in the middle of the rectifier and the inverter in order to have faster and more accurate analysis of harmonics on both the utility and the motor side. Finite element analysis shows that reducing current harmonic level causes lower core losses in the machine. Each component from the simulation, specifically synchronous generator, phase shifting transformer, multipulse rectifier, multilevel inverter, umbilical cable and induction motor, can be replaced or combined with any other topologies which is one of the biggest benefits of the system based modeling and simulation

    Realization of a 10 kW MES power to methane plant based on unified AC/DC converter

    Get PDF
    This paper presents a galvanic isolated multi output AC/DC topology that is suitable for Microbial electrosynthesis (MES) based Power to Methane energy storage systems. The presented scheme utilizes a three phase back to back converters, a single-input and multiple-output three phase transformer, single diode rectifiers and buck converters that employ a proper interconnection between MES cells and the mains. The proposed topology merges all the required single phase AC/DC converters as a unified converter which reduces the overall system size and provides system integrity and overall controllability. The proposed control scheme allows to achieve the following desired goals:1) Simultaneous control of all cells; 2) Absorbing power from the grid and covert to methane when the electricity price goes down; 3) the power factor and the quality of grid current is under control; 4) Supplying MES cells at the optimal operating point. For verification of system performance, Real time simulation results that are obtained from a 10-kW MES energy storage are presented.Postprint (author's final draft

    The Proposal for Implementation of Controlled Power Rectifier (3000/4000KW) in MTA New York City Transit (MTA-NYCT)

    Full text link
    The MTA New York City Transit (MTA-NYCT) will require a robust and reconfigurable power system capable of supplying high power in order to be able to provide services based on for cased future forecast growth of the city population. A critical component in such a system is the Phase Controlled Rectifier. As such, the issues associated with the inclusion of a power electronics rectifier need to be addressed. These issues include input Alternating Current (AC) interface requirements, the output Direct Current (DC) load profile, and overall stability in the output voltage for Train car loads. Understanding these issues, providing possible solutions and determining the means of assuring smooth compatibility with MTA New York City Transit (MTA-NYCT) Traction Power systems is the focus of this thesis. By using a SimulinkÂź model of an actual MTA-NYCT Traction Power System, actual train car load, 12 -Pulse count, high power rectifiers were exercised. The SimulinkÂź results are compared between the Traction Power Systems of Uncontrolled Rectifier and Controlled Rectifier analysis results. In subway normal operation hour, with uncontrolled rectifier systems, subway cars load current level are 2800 Amps to 3600 Amps, and Voltage level 450 VDC to 600 VDC in running condition. In this Simulation, with controlled rectifier system, subway cars load current level are 3200 Amps to 4000 Amps, and Voltage level 550 VDC to 625 VDC established. These experiments led to the conclusion that increasing the continuous current and the overall stability in the output voltage, reducing the harmonics, there are tradeoffs in terms of complexity and size of the passive components, and optimization based on source and load specifications is also required.

    Addressing control and capacitor voltage regulation challenges in multilevel power electronic converters

    Get PDF
    Multilevel power electronic converters are the current industry solutions for applications that demand medium voltage, reasonable efficiency, and high power quality. The proper operation of these types of power converters requires special control, modulation methods, and capacitor voltage regulation techniques. Both developing capacitor voltage regulation methods and addressing their associated issues with such fall within the primary focus of this dissertation. In this dissertation an investigation was conducted on the capacitor voltage regulation constraints in cascaded H-bridge multilevel converters with a staircase output voltage waveform. In the proposed method, the harmonic elimination technique is used to determine the switching angles. A constraint was then derived to identify modulation those indices that lead to voltage regulation of the capacitor. This constraint can be used in optimization problems for harmonic minimization to guarantee capacitor voltage regulation in these types of converters. Furthermore, a capacitor voltage regulation method was developed using redundant state selection for a flying capacitor active rectifier. This method reduces the number of switching instances by using both online and offline state selection procedure. Additionally, a start-up procedure is proposed that pre-charges the all of capacitors in the rectifier to both avoid overstressing the switches and obtain a smoother start-up. Finally, a flexible capacitor voltage regulation method is proposed that provides the ability to control the voltage of the capacitors in both cascaded H-bridge and hybrid multilevel converters. In this method, the capacitor voltage in each individual H-bridge cell is independently regulated by controlling the active power of each cell
    • 

    corecore