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Power Electronics, IEEE Transactions on

Issue 5 • Date Sep 1994

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Displaying Results 1 - 11 of 11
  • Power spectra of a PWM inverter with randomized pulse position

    Page(s): 463 - 472
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    Random pulse width modulation in static power converters results in the partial transfer of power from the discrete spectrum of the output voltage to the continuous spectrum, with advantageous effects on the operation of the supplied electromechanical systems. In this paper, a random PWM technique with randomized pulse position for three-phase voltage-controlled inverters is analyzed. Closed-form equations for the discrete and continuous power spectra of the line-to-line and line-to-neutral voltages of the inverter have been derived and confirmed by experiments. Presented theory opens the way to numerical optimization of the voltage spectra of randomly modulated inverters View full abstract»

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  • Disturbance observer based fully digital controlled PWM inverter for CVCF operation

    Page(s): 473 - 480
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    A new approach for digital feedback control of a PWM inverter is proposed, in which an output DB (deadbeat) control is achieved combined with a disturbance observer. In the proposed scheme, the pole placements of the state observer and the disturbance observer are chosen separately. When the two observers employed the same pole placements, the experimental setup had a tendency to become unstable due to the detection error. By selection of the different pole placements, the disturbance observer quickly estimates the disturbance and feedforward disturbance cancellation is achieved. Then the state observer estimates the state variables at the next sampling instant, and the deadbeat controller is applied to the nominal system. This scheme has advantages in robustness in the practical application. From the view point of UPS applications, the advantages and disadvantages are discussed through simulations and experiments. Compared with other digital control laws, the superiority of the proposed control law is verified View full abstract»

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  • Three-level space vector PWM in low index modulation region avoiding narrow pulse problem

    Page(s): 481 - 486
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    In using GTO, a few hundreds micro seconds longer than specified pulse width must be guaranteed for safety for each device to commutate with its inherent gate current sequences. This paper describes the mechanism of generating undesirable narrow pulses in conventional three-level space vector PWM inverters and suggests two new algorithms of space vector PWM using nonnearest three and four vectors in a control period to avoid such a narrow pulse problem. Experimental verifications for the suggested algorithms are also presented View full abstract»

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  • A modular concept for the circuit simulation of bipolar power semiconductors

    Page(s): 506 - 513
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    Physical network simulation models of bipolar power devices strongly depend on an accurate description of the low-doped drift zone, because the behavior of the diffusion charge in this region governs the static and dynamic device characteristics. In this paper a one-dimensional modeling module for the drift zone is presented, which accounts for all important effects under high injection conditions: nonquasistatic ambipolar diffusion, temperature- and injection-level dependent scattering and recombination effects as well as impact ionization. When combined with well known expressions describing the rest of the respective structure, very accurate and CPU-time efficient network models can be implemented, that are suited for all applications including resonant modes (ZVS, ZCS, ZVT). The module is incorporated in a commercially available network simulator and used so far for modeling the IGBT, the high power diode and the GTO View full abstract»

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  • An experimentally verified IGBT model implemented in the Saber circuit simulator

    Page(s): 532 - 542
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    A physics-based IGBT model is implemented into the general purpose circuit simulator Saber. The IGBT model includes all of the physical effects that have been shown to be important for describing IGBTs, and the model is valid for general external circuit conditions. The Saber IGBT model is evaluated for the range of static and dynamic conditions in which the device is intended to be operated, and the simulations compare well with experimental results for all of the conditions studied View full abstract»

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  • CAD tools to optimize power MOSFET performance using channel reverse conduction

    Page(s): 522 - 531
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    In this paper, a contribution to the characterization of power MOS transistors under optimized switching behavior is presented. This behavior is shown to be appropriate for improving the performance of new high frequency power processing topologies. Reverse conduction through the channel resistance is imposed, thus avoiding the problem of integral diode recovery time without resorting to external diodes. Control circuit design is discussed. Advantages and drawbacks are analyzed and tested in a series resonant converter. An insight into MOSFET reverse conduction modeling is presented, aimed at the development of an accurate model for computer aided design of topologies using the MOSFET's bidirectional paths. Simulation results are shown to prove the accuracy of the model View full abstract»

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  • On the modeling of PWM converters for large signal analysis in discontinuous conduction mode

    Page(s): 487 - 496
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    Several methods have been developed until today for the analysis of PWM converters operating in discontinuous conduction mode (DCM) and many endeavours have been done in order to solve two well known problems: the nontrivial calculation of the internally controlled instant at which the current flowing into the diode falls to zero and the subsequent order reduction of the state-space model of the circuit due to the disappearance of one state variable. In this work a new approach to the modeling of PWM converters for the large signal analysis in DCM operation is presented. It is based on a closed-form discrete-time state-space model obtained by introducing a time-adaptive function for the calculation of the instant at which the diode current falls to zero, and an equivalent fictitious configuration of the circuit during the idle phase, in order to prevent the unconditioned order reduction of the state-space model. A four-terminal device is also introduced which allows a unified representation of the PWM buck, boost, buck-boost, and Cuk converters in DCM operation using the fictitious configuration. The model proposed can be used for circuit oriented simulations both in open and closed loop operation and for an accurate ripple inspection, automatically accounting for DCM to CCM (continuous conduction mode) transitions and vice versa View full abstract»

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  • A method for reducing harmonics in output voltages of a double-connected inverter

    Page(s): 543 - 550
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    A new method for reducing the harmonics involved in the output voltages of a double-connected inverter is proposed. By adding four auxiliary switching devices and an interphase transformer with a secondary winding to the conventional 12-step inverter, output voltages of the proposed circuit can produce almost the same waveforms as a conventional 36-step inverter. In this paper, circuit performances and output voltage waveforms are discussed, and optimum parameters are derived. The effects on harmonic reductions are then clarified by theoretical and experimental results, and the ratings of system components are investigated View full abstract»

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  • A unified method for modeling semiconductor power devices

    Page(s): 497 - 505
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    A unified method for modeling semiconductor power devices has been developed. The novelty of the method is a generalized description of the lightly doped region which is a common feature of all power devices. The charge carrier distribution in this region is calculated with a fast numerical algorithm. Depending on this carrier distribution the voltage across the low doped zone is calculated with analytical equations. This so called hybrid-description can be adjusted to the physical behavior of all power devices. By combining the hybrid-model with an analytical description of the remaining high doped regions the complete power device is described. The method has been applied to the power diode, the power bipolar transistor, and the IGBT. The developed circuit models have been implemented in a commercial circuit-simulator. The simulation results have been compared with measurements View full abstract»

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  • A study of design influence on anode-shorted GTO thyristor turn-on and turn-off

    Page(s): 514 - 521
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    Anode-shorted GTO thyristor samples were investigated by means of the free-carrier absorption (FCA) technique. Both the turn-on and turn-off processes were investigated as regards the two-dimensional carrier distribution for different stages of the transient cycles. The results are presented as carrier-map sequences, i.e., 3-D pictures of measured 2-D carrier distributions. Samples were formed as unit segments cut out from large-area devices, and associated with different degrees of anode shorting, silicon thickness, and lifetime treatment. During investigation, the samples were inductively anode loaded, and as regards the turn-off process they were operated near the safe-operation limit. The measurements clearly illustrate the way carriers are transported in the sample when firing the device, and the turn-on process is visualized in steps by means of carrier-map sequences. These measurements are supported by computer simulations. The turn-off process is also visualized in carrier-map sequences measured from two perpendicular directions, and the maps show the critical electric-field expansion which always precedes a turn-off failure due to dynamic breakdown mechanisms. Further on, the effect of design-parameter variations, e.g., anode shorting pattern and carrier lifetime reductions, on destructive GTO turn-off phenomena are discussed View full abstract»

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  • Study and implementation of a simplified and robust position digital controller for a PM synchronous actuator

    Page(s): 457 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    This paper presents a fully digital position control system for small power surface mounted PM synchronous actuators. The control algorithm relies on a simplified decoupling state feedback in order to obtain field orientation. There is no current measurement, and the current values needed to compute the control algorithm are predicted from a model. This makes it possible to use a fully digital position controller by using low cost 8 bit microprocessors with only a position sensor. Moreover, it is shown in this paper that it is preferable to use, in the decoupling state feedback, an estimated, instead of a measured, value of the current to ensure stability and to improve the robustness of the system regarding parameter uncertainties. Furthermore, as the actuator model is linearized by a decoupling state feedback, the robustness of the system has been further improved by using appropriate techniques evolved for linear systems to synthesize the position controller. The performance of the proposed control system is analyzed by a theoretical study and digital simulations. It has been implemented around two 8 bit MCS 8051 microcontrollers and tested on a 2 kW machine View full abstract»

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Aims & Scope

IEEE Transactions on Power Electronics covers fundamental technologies used in the control and conversion of electric power.

Full Aims & Scope