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Energy Conversion Congress and Exposition (ECCE), 2010 IEEE

Date 12-16 Sept. 2010

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Displaying Results 1 - 25 of 659
  • 2010 chair welcome

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  • Schedule

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  • Table of contents

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  • Author index

    Page(s): 1 - 219
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  • 2010 IEEE energy conversion congress & expo

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  • Call_11

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  • [Copyright notice]

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  • A frequency demodulation approach to induction motor speed detection

    Page(s): 1 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (937 KB) |  | HTML iconHTML  

    Rotor slot harmonics are found in the stator current waveforms for most squirrel-cage induction motors. These harmonics are caused by the finite number of rotor slots in a motor, and their frequencies are inherently correlated with the motor's rotational speed. A frequency demodulation approach is proposed in this paper to continuously and accurately track the rotational speed for grid-connected induction motors during either dynamic or steady-state motor operations. First, a complex current vector is synthesized from polyphase electrical current measurements. Second, a local oscillator and mixer are cascaded with a digital filter to heterodyne a specific rotor slot harmonic and suppress adjacent interferences. A finite impulse response differentiator is then employed as a frequency demodulator to approximate the time derivative of the phase of this specific rotor slot harmonic, and resolves its instantaneous frequency. Finally the induction motor speed is calculated from this resolved instantaneous rotor slot harmonic frequency. Experimental results demonstrate that the proposed scheme is capable of interleaving data acquisition with real-time computation, iteratively estimating motor speed on a sample-by-sample basis. View full abstract»

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  • Optimal split ratio for high speed induction machines

    Page(s): 10 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (641 KB) |  | HTML iconHTML  

    The split ratio of several types of electrical machines has been identified as an important optimisation parameter. While the optimisation of split ratio in high-speed permanent magnet, switched reluctance and flux-switching machines has been researched, this parameter has often been neglected in the design of high-speed induction machines. In this paper, using a described multi-domain design environment which puts equal weight on the electromagnetic, mechanical and thermal aspects, the rotor split ratio together with the rotor slot shape and electric and magnetic loadings are identified as important and sensitive parameters in the design of high speed, high power density laminated-rotor induction machines. This is shown using a design case study which involves improving the power density of an existing 10 kW, 75kpm laminated rotor induction machine. View full abstract»

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  • Effect of winding asymmetries and winding connection on small synchronous machines

    Page(s): 17 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    This paper reports on the study of winding asymmetries in small synchronous generators. These types of generator are commonly used in diesel generator or back-up systems and are usually no more than a few or few tens of kilowatts with two, four or six salient poles. The 3-phase winding is 120 deg pitched but often lap windings are not used, rather a hybrid of concentric winding and double layering is utilized. There are sound manufacturing reasons for this and these are explained. This leads to small asymmetries in the phase-belt inductances and field-induced voltages. This is examined and validated experimentally. The paper discusses the techniques that are used to analyze the machine. These are analytical methods although a discussion about finite element analysis is put forward. The methods address the correct positional coil groupings in the slots to obtain back-EMFs, mutual and self-inductances and line currents. These are obtained over a varying load range. View full abstract»

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  • New method for current and voltage measuring offset correction in an induction motor sensorless drive

    Page(s): 23 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1179 KB) |  | HTML iconHTML  

    This paper presents a new algorithm for electromagnetic torque and flux estimation in a sensorless drive when uncompensated dc offset of current and/or voltage sensors are present. The novel feature of the offset error correction algorithm is an attempt not to eliminate the consequence of problem but to identify its source. The algorithm uses the first harmonic of estimated torque and dc value of estimated stator flux to identify the source and value of the current and/or voltage offset error. Identified values can be used for offset cancelation which improves estimation process. View full abstract»

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  • Modularized bi-directional grid-tied inverter with asynchronous sigma-delta modulation

    Page(s): 31 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1678 KB) |  | HTML iconHTML  

    The objective of this paper is to propose a modularized bi-directional grid-tied inverter (BGI) with asynchronous sigma-delta modulation (ASDM) control for the renewable energy (RE)-supplied DC power system. The proposed BGI can be operated either in the grid-tied mode (GTM) or the power factor correction mode (PFCM) which is necessary features for the RE-supplied DC power system. The proposed BGI with ASDM control scheme has the merits of circuit simplicity, quick response, and low electromagnetic interference. Moreover, the proposed BGI has redundant central controller which can increase the system reliability. The major contribution of this paper includes that developing the modularized BGI with ASDM control scheme for GTM and PFCM operations thoroughly and applying it to the RE-supplied DC power system successfully. In this paper, the mathematical equations of the proposed BGI with ASDM will be derived. Computer simulations and hardware experiments are shown to verify the performance of the proposed modularized BGI with ASDM control. View full abstract»

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  • Predictive digital controlled three phase bi-directional inverter with wide inductance variation

    Page(s): 37 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1404 KB) |  | HTML iconHTML  

    This paper presents predictive digital controlled three phase bi-directional inverter with wide inductance variation. The bi-directional inverter can fulfill both grid connection and power factor correction. With a predictive digital control, the inverter is allowed to have a wide inductance variation, reducing core loss and size significantly. The proposed predictive digital control laws can be derived with either an accurate approach or an approximated one. In the design and implementation, the inductances corresponding to various currents are measured, and tabulated into a single-chip controller for tuning loop gain cycle by cycle, ensuring system stability. Measured results from a 10 kW 3φ bi-directional inverter have been presented to confirm the feasibility of the discussed inverter. View full abstract»

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  • Design and implementation of a 5 kW 1φ bi-directional inverter with wide inductance variation

    Page(s): 45 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    This paper presents design and implementation of a 5 kW 1 φ bi-directional inverter with wide inductance variation. The bi-directional inverter can fulfill grid connection and power factor correction, in which inductor current can vary from 0 to 32A in one line cycle. This will result in wide inductance variation, around 7 times for an inductor constructed with an MPP core, and thus high current ripple and high current fluctuation. In this paper, we take into account this variation while designing controller and selecting key components to ensure inverter normal operation. Additionally, to adopt a cost effective microcontroller for the inverter, the sensitivities of the control to various parameters are investigated and presented in the paper. Experimental results measured from a 5 kW 1 φ prototype have verified the feasibility of the designed inverter. View full abstract»

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  • A novel control method for dual mode time-sharing grid-connected inverter

    Page(s): 53 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB) |  | HTML iconHTML  

    A dual mode time-sharing inverter has higher efficiency than other type grid-connected inverter due to only one power stage of it working in high frequency state at any time. In this paper, small signal modeling of this inverter is carried out, which reveals that the control-to-grid current transfer function of this inverter has a right half plane zero at low frequency during the “Boost” operating stage which results in the difficulty in controlling the system. An indirect current control method based on instantaneous power balance is proposed. The right-half plane zero can be eliminated and a satisfactory compensator with enough phase margin and amplitude margin can be obtained with this new control strategy. And it is evaluated through simulation and experimental results of a 1kW prototype. View full abstract»

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  • Inverter-based versus synchronous-based distributed generation; fault current limitation and protection issues

    Page(s): 58 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (824 KB) |  | HTML iconHTML  

    The contribution of distributed generation (DG) to network fault levels depends heavily on the technology employed. In the case of directly connected rotating machines the fault behavior is well established; with synchronous generators contributing higher fault levels than the corresponding induction generators. The contribution of inverter-based distributed generation (IBDG) is the lowest due the capability of this technology to exhibit non over-load characteristics. However the behavior of this generation technology under fault conditions is determined by the employed control methods. In this paper, an investigation of the effect of the DG type on the fault current is investigated. Simulations for case studies have been conducted using Matlab/Simulink. View full abstract»

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  • Protection of meshed microgrids with communication overlay

    Page(s): 64 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    The higher reliability of meshed grids, whether in power or communication, when compared with radial grids is well established. However, while meshed grids provide higher reliability, protection of meshed grids is challenging. In smaller systems such as microgrids, line impedances can be small and many branches may experience approximately the same level of fault current. Locating faults quickly before damage to the equipment and system occurs becomes a non-trivial task and cannot be achieved without communication. This paper discusses a comprehensive scheme for protecting meshed microgrids with multiple levels of protection for redundancy. Power line carrier (PLC) technology is proposed as cost effective and robust means of communication, obviating the need for additional cabling. View full abstract»

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  • Power sequencing approach to fault isolation in dc systems: Influence of system parameters

    Page(s): 72 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (609 KB) |  | HTML iconHTML  

    We show that medium-voltage dc power buses can be protected against short circuit faults by coordinating the action of a converter that supplies power to the bus with the action of contactors that are used to reconfigure the bus connections. Following a fault, the bus is de-energized (so there is no large current to interrupt), one or more contactors are reconfigured, and the dc bus is then reenergized. For a typical industrial dc bus, we show that it is possible to execute this de-energize-reconfigure-re-energize process 10 times faster than an AC bus can be protected and reconfigured using traditional circuit breakers. We show how the de-energizing and reconfiguring times depend on the output capacitance of the main converter and on the distance to the fault, and we show how to size each hold-up capacitor so that loads on unfaulted circuits can ride through the process uninterrupted. View full abstract»

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  • Research on current control strategy for grid-connected inverter based on passivity based control

    Page(s): 79 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB) |  | HTML iconHTML  

    In the micro-grid, the grid-connected inverter and its filter are important to convert and transmit the energy. In this paper, a T filter is used to reduce the harmonics of the grid-current. However, it will be lack of enough stability. In order to overcome this obstacle, a new passivity based controller, namely IDA-PBC is proposed in this paper. And the paper analyses the stability of the controller in detail. The correctness and validity of the proposed control algorithm are proved to achieve stability with good stability and dynamic ability by simulation and experimental results. View full abstract»

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  • Electromechanical characterization of “flying” Planar Gate Punch Through IGBT bare die

    Page(s): 84 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1730 KB) |  | HTML iconHTML  

    The effect of mechanical stress on the power dice is investigated by considering the application of mechanical stress on a Punch Through Planar Insulated Gate Bipolar Transistor under static electrical characterizations. Specific test vehicles and test bench for applying a tensile or compressive mechanical stress are described in detail. Furthermore, 2D finite element simulations are carried out to understand the device behavior by internal physics analysis. The impact of the mechanical stress cannot be neglected. Indeed, the results show a similar tendency between simulations and experiments for two static electrical characterizations: the output characteristics are sensitive to mechanical stress whereas the effect is negligible on the breakdown voltage. The case of the threshold voltage shows a disparity between experiments and simulations. Globally, such silicon property might be a key point to propose a real-time monitoring of the mechanical state evolution of the power assemblies. View full abstract»

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  • Robustness evaluation of high voltage Press Pack IGBT modules in enhanced short circuit test

    Page(s): 92 - 99
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (667 KB) |  | HTML iconHTML  

    The paper deals with the evaluation of robustness of high power Press Pack IGBT modules under short circuit conditions. The severity of the tests is usually related to the achievement of the real failure mode which drives the device to withstand a big amount of energy. The most and well known methods to evaluate the robustness of the devices have been analyzed and improved in order to operate with the highest achievable di/dt and to consequently emulate the real circuit setup and failure mode. Experimental tests will be shown and evaluated under different voltage and temperature conditions. The tests described in the paper have been targeted to evaluate the capability of the device to withstand extremely severe condition when they are used in a high power converter. A driving protection feature dealing with the target of improving the functionality of protection against failure will be also described. View full abstract»

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  • Comparisons of 6.5kV 25A Si IGBT and 10-kV SiC MOSFET in Solid-State Transformer application

    Page(s): 100 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    A 6.5 kV 25 A dual IGBT module is customized and packaged specially for high voltage low current application like solid state transformer and its characteristics and losses have been tested under the low current operation and compared with 10 kV SiC MOSFET. Based on the test results, the switching losses under different frequencies in a 20 kVA Solid-State Transformer (SST) has been calculated for both devices. The result shows 10 kV SiC MOSFET has 7-10 times higher switching frequency capability than 6.5 kV Si IGBT in the SST application. View full abstract»

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  • Modeling of the impact of diode junction capacitance on high voltage high frequency rectifiers based on 10kV SiC JBS diodes

    Page(s): 105 - 111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    There is strong industrial need to boost the power density of the high voltage generators, for example, in medical radiology applications. 10 kV SiC JBS diode is potential candidate to be employed in the high voltage high frequency rectifier in future high voltage generator applications. However, the impact of the relatively large diode junction capacitance of SiC JBS diode cannot be neglected at high frequency and high voltage conditions. An electric circuit model is proposed to describe this effect for full bridge and half bridge high voltage diode rectifiers based on mathematical derivations. The effect of junction capacitance is to decrease the output voltage and to increase the ratio of capacitive reactive power in the circuit, which can be represented by an equivalent shunt capacitor with input source and ideal diode rectifier. The model is validated by simulation results, and can be used for the further design of the high voltage generators. View full abstract»

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  • Power electronics for sustainable energy future - quantifying the value of power electronics

    Page(s): 112 - 119
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB) |  | HTML iconHTML  

    Power electronics is the key technology for the efficient use, distribution and generation of electrical energy. It is estimated that by wider adoption of power electronics about 30% of reduction in electrical energy consumption can be achieved. For many applications technologies are already available but the biggest obstacle to the further market penetration of power electronics are Economy, Policy and Public Acceptance. We need to find better and more effective ways to present the importance and value of power electronics in a way that can be understood by policy makers and that can capture the imagination of the general public. In this paper some possibilities are explored of how we could quantify and explain the added value of using more power electronics. Energy payback time is shown to be a powerful tool to weigh the value of energy savings achieved by using power electronics against the energy needed to manufacture the systems. It is shown that power electronics systems have considerably shorter energy payback time compared to other technologies required for achieving a fully sustainable energy system. View full abstract»

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  • Lowest cost path to meeting electricity demand at the state level: Implications of carbon cap-and-trade

    Page(s): 126 - 131
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (469 KB) |  | HTML iconHTML  

    We develop a linear optimization model at the state level, and use this model to investigate how policy constraints on greenhouse gas emissions may affect the lowest-cost choices for electricity generation over the next twenty years. The state-level model provides local and regional decision-makers with a basis for understanding the potential impacts of policy changes, and provides a basis for planning and policy analysis. View full abstract»

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