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Power Electronics Specialists Conference, PESC '94 Record., 25th Annual IEEE

Date 20-25 June 1994

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Displaying Results 1 - 25 of 108
  • Learning techniques to train neural networks as a state selector for inverter-fed induction machines using direct torque control

    Page(s): 233 - 242 vol.1
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    Neural networks are receiving attention as controllers for many industrial applications. Although these networks eliminate the need for mathematical models, they require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability and weight convergence remain as areas of research and comparison of many training algorithms. This paper discusses the application of neural networks in control of induction machines using direct torque control (DTC). The neural network is used to emulate the state selector of the DTC. The algorithms use to train the neural network are: the back propagation, adaptive neuron model, extended Kalman filter and the parallel recursive prediction error. Computer simulations of the motor and neural network system using the four approaches are presented and compared. The parallel recursive prediction error and the extended Kalman filter algorithms as the most promising training techniques are discussed, giving its advantages over other techniques.<> View full abstract»

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  • Proceedings of 1994 Power Electronics Specialist Conference - PESC'94

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    Freely Available from IEEE
  • Adaptive vector control of induction motor drives based on a neuro-fuzzy approach

    Page(s): 225 - 232 vol.1
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    The paper deals with the design and the experimental realization of an MRAC speed controller for indirect field oriented induction motor drives, based on using fuzzy laws for the adaptive process and a neuro-fuzzy procedure to optimize the fuzzy rules. The variation of the rotor time constant is also compensated by performing a fuzzy fusion of three simple compensation strategies. A performance comparison between the new controller and a conventional MRAC control scheme is carried out by means of simulations confirming the superiority of the proposed fuzzy adaptive regulator. A prototype based on an induction motor drive has been assembled and used to practically verify the features of the proposed control strategy View full abstract»

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  • Modelling of power semiconductor devices for use in circuit simulations

    Page(s): 38 - 43 vol.1
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    The combined use of several modelling techniques and tools to derive realistic models of power semiconductor devices for use in circuit simulations is illustrated using the GTO thyristor as an example. The resulting GTO model uses analytical expressions to describe its internal physics. Direct implementations of these equations in the SPICE and Saber simulators are then used to obtain rigorous comparison of measured and simulated waveforms View full abstract»

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  • Zero current soft switching mode parallel load resonant tank high-frequency inverter using normally off bipolar mode SIT

    Page(s): 95 - 101 vol.1
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    This paper is mainly concerned with a half-bridge quasi-resonant voltage-clamped high-frequency induction-heating inverter circuit using a high-power bipolar-mode normally-off type static induction transistor (B-SIT) for soft-switching, which efficiently operates at a zero-current soft-switching (ZCS) mode. This proposed inverter using newly developed B-SIT module is more suitable for modern induction-heating power supplies. Its new conceptional operating principle is basically presented and its features are discussed. Its computer-aided simulation results are illustrated as compared with the experimental results obtain from a trially-produced breadboard with parallel load resonant tank View full abstract»

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  • A systematic approach to modeling of power semiconductor devices based on charge control principles

    Page(s): 31 - 37 vol.1
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    The charge control approach to modeling is extended to power devices by converting device equations to charge modules, which can then be used to assemble device models. This method represents a systematic technique for constructing models for power electronic circuit simulation. The resulting models are represented by relatively simple functions which are valid over a wide range of operation View full abstract»

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  • A precise model for the DC and transient characteristics of BJTs

    Page(s): 64 - 68 vol.1
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    This paper presents a circuit model of a BJT based on the calculation of the charge carrier distribution in the base and in the lightly doped collector layer by approximation of the time derivatives. All important phenomena like transient behaviour, emitter and collector recombination, temperature dependence and conductivity modulation are included. Excellent agreement can be observed between simulations and measurements View full abstract»

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  • Bi-frequency control for quasi-resonant converters

    Page(s): 309 - 314 vol.1
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    A new control technique for quasi resonant converters, called the bi-frequency control, is proposed. This control technique can regulate the output of quasi-resonant converters at two fixed switching frequencies without adding an auxiliary switch. The basic principle of the bi-frequency control is presented. Based on a zero-voltage-switching buck converter, the theoretical analysis and design procedures are given. PSPICE simulations are used to demonstrate the operation, and a 50 watts prototype is implemented to verify the analytic work View full abstract»

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  • Family of two-switch soft-switched asymmetrical PWM DC/DC converters

    Page(s): 85 - 94 vol.1
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    In this paper, the inter-relationships among two-switch, soft-switched, PWM converters are explored. Starting from a generalized two-switch converter operated under an asymmetrical PWM scheme, the paper first conceptually derives the nonisolated converters-both hard-switched and soft-switched types. Isolated versions with output inductive and capacitive filtering are then introduced. The inclusion of the primary side leakage inductance to aid the ZVS mechanism in the inductive filtering variation is addressed. The operations of the converters are discussed in detail. Results of the DC analysis for all the converters are also given. Finally, comparative evaluation of the different converters is provided. All the converters generally have the advantages of lossless switching, minimum switch voltage stress, fixed frequency operation and minimum component count. Though many of the converters have been described elsewhere, the paper integrates them under a common qualitative and theoretical framework View full abstract»

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  • A new current fed type PWM inverter system using instantaneous vector control

    Page(s): 149 - 153 vol.1
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    This paper proposes a new PWM strategy of the current fed type inverter based on instantaneous vector control. In this system, the output voltages can be obtained directly by feedback control of the instantaneous vector. So, the proposed inverter system has a simple control circuit, fast response, and robustness against disturbances. In addition to these, it is possible that pure sinusoidal waveforms of load currents may be achieved by reducing the ripple of the output voltages under the inductive load View full abstract»

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  • Large-signal transient response of regulated resonant converters

    Page(s): 109 - 114 vol.1
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    Large-signal transient responses of regulated resonant converters are investigated by analysis and experiment. The maximum peak values of the voltage stress on the semiconductor switch, reactor current and output voltage are obtained for the step-change of the line voltage and the load condition. As a result, a much higher voltage appears across the semiconductor switch for a larger variation of the line voltage compared with the steady state voltage. A comparison of large-signal transient responses clarifies that full-wave resonant converters have much higher voltage-stress on semiconductor switches compared with their half-wave counterparts, and that full-wave converters show a faster response of the output voltage than their half-wave counterparts View full abstract»

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  • ZACE current controlled power flow for AC-DC power converters

    Page(s): 539 - 545 vol.1
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    Unity and controlled power factor AC-DC power converters require a current control technique with zero average current error (ZACE) in each switching period. Acting on the current error signal alone, a ZACE controlled converter offers complete real and reactive power flow control with negligible low order current harmonics, a narrow switching frequency band, and relative immunity to DC link or AC line voltage harmonics. Slope-generated hysteresis, a new ZACE current control method is introduced. Simulation and experimental results in a three phase converter are presented View full abstract»

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  • Soft-transition three-phase PWM conversion technology

    Page(s): 79 - 84 vol.1
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    By recognizing common topological properties of PWM converters and of available semiconductor switches, a new generalized soft-switching principle (soft-transition (ST) principle) is developed for the elementary PWM switching cell. Application of the ST principle opens a way of implementing many different new soft-switching PWM topologies. Its application is especially valuable in three-phase converters where the circuit complexity and presence of AC variables can often obscure possible ways of applying the ST technique. The generalized ST principle was successfully used for the development of two novel ZVT rectifier topologies View full abstract»

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  • On-line improved inverter waveform by variable step delta modulation

    Page(s): 143 - 148 vol.1
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    This paper presents a new technique using delta modulation for inverter operation. Delta modulation (DM) schemes have the ability to optimize pulse width modulated (PWM) inverter waveforms online. The tuned and the multi-integrator DM are the two schemes proposed for PWM waveform synthesis so far. The methods were found useful for variable speed PWM inverter-fed AC drives. However it was observed that during tuning and filtering process, fundamental output voltage of the inverters reduced. With an aim to overcome this effect, a new technique called the variable step rectangular wave delta modulation (RWDM) is proposed. The method has the capability to maintain a near constant fundamental voltage of the output waveform of the inverters. Both analytical and experimental verifications are carried out for tuned and variable step RWDM View full abstract»

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  • Analysis of the improved soft-commutated PWM inverter by using an AC current transformer

    Page(s): 719 - 726 vol.1
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    In the high power DC-DC converter and DC-AC inverter, the soft-commutated PWM technique has been receiving much attention from the viewpoints of decreasing the switching noise, reducing the switching power loss in the main power switch and removing the complicated snubber circuit and so forth. However, the conventional soft-commutated PWM converter and inverter have some defects such as high voltage and/or high current stresses on the switches, the necessity of the additional switches for realizing soft-commutation, and the relatively large power loss caused by the large circulating current composed of the load and resonant ones. This paper presents an improved half-bridge type soft-commutated PWM inverter, in which an AC current transformer and an additional resonant capacitor are employed to realize the soft-commutated PWM operation of the switches and to decrease the circulating current. Consequently, in the proposed circuit. the power loss caused by this circulating current is sufficiently reduced. The operation performance characteristics of this soft-commutated PWM inverter are analyzed View full abstract»

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  • Evaluation and comparison of predictor models for rotor flux calculation in induction motors

    Page(s): 729 - 737 vol.1
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    A thorough method for evaluation and comparison of predictor models (models and observers) for rotor flux calculation is presented. A number of predictor models are investigated using the established procedure. The lowest overall sensitivity to parameter deviations and measurement errors is found in predictor models with voltage model and current model behaviour in the higher and lower frequency ranges, respectively View full abstract»

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  • Operation of the unified power controller as harmonic isolator

    Page(s): 169 - 176 vol.1
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    The unified power controller (UPC) is a tool in the implementation of flexible AC transmission systems (FACTS). It provides for the equivalent of static VAr compensation and series injection using back-to-back force commutated converters. This paper proposes a control strategy to extend UPC operation to allow for the isolation of harmonics due to nonlinear loads. Simulation results based on the Electromagnetic Transients Program (EMTP) are used to illustrate device performance in a power system environment. Experimental results based on a single phase laboratory implementation verify the proposed control algorithm View full abstract»

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  • DC-side shunt active power filter for phase-controlled magnet-load power supplies

    Page(s): 183 - 188 vol.1
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    Phase-controlled thyristor rectifiers are still the preferred choice in high power applications. This paper shows that their steady state and dynamic performance can be greatly enhanced in high-precision and fast-response electromagnet power supplies by means of a shunt active power filter using a high-frequency PWM converter. In this hybrid structure, the rectifier is designed to handle the bulk of the output power, whereas the PWM converter is only used for harmonic cancellation and current error compensation under transient conditions. This results in a small power rating for the shunt active filter. A suitable control scheme is proposed and implemented in this paper for the rectifier and the PWM converter. Experimental results are provided to validate the proposed concept View full abstract»

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  • A novel control evaluation technique for resonant converters

    Page(s): 301 - 308 vol.1
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    The novel analysis technique for resonant converter (RC) control is developed that is based on converter performance evaluation on the state plane and in discrete-time domain. This technique allows one to predict the steady state regime existence and its important features through graphical state-plane consideration. To examine control dynamics, a new effective approach to RC nonlinear difference equations analysis is advanced that reveals converter small and large signal stability as well as transient character and speed. The proposed method was employed for comparative analysis of accustomed control methods in application to series RC and led to deeper insight of their operation View full abstract»

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  • Zero-voltage and zero-current-switching full bridge PWM converter for high power applications

    Page(s): 102 - 108 vol.1
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    A novel zero-voltage and zero-current-switching (ZVZCS) full bridge (FB) PWM converter is proposed. The new converter overcomes the limitations of the ZVS-FB-PWM converter such as high circulating energy, severe parasitic ringing on the rectifier diodes, and limited ZVS load range for lagging leg switches. By utilizing the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging leg switches to be operated with ZCS. Meanwhile, the leading leg switches are still operated with ZVS. The new converter is attractive for high voltage, high power applications where IGBTs are predominantly used as the power switches. The principle of operation, and DC characteristics of the new converter are analyzed and verified on a 2 kW, 83 KHz experimental circuit View full abstract»

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  • Vector control of synchronous reluctance motors including stator-iron loss with on-line parameter measurement

    Page(s): 508 - 513 vol.1
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    This paper describes the vector control of a synchronous reluctance motor with on-line parameter measurement based on the voltage equation taking account of the stator iron loss. The vector control is achieved by using nonlinear state feedback to eliminate the interference of d-q axes through the equivalent iron loss resistance in transient conditions. The parameters of the vector controller are adjusted to achieve the vector control of synchronous reluctance motors in the case that machine parameters have variations View full abstract»

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  • Worst case stability analysis of switching regulators using the structured singular value

    Page(s): 281 - 288 vol.1
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    A method to assess the effect of component tolerances on the stability of closed loop switching regulators is given. Use of μ, the structured singular value, is made which obviates the need for time intensive Monte-Carlo simulation runs and also guarantees the assessment of the worst case condition of the system. Furthermore, through the use of newly developed software routines for μ, the effect of up to a hundred uncertainties may be taken into account. The analysis procedure entails isolating component value uncertainties from the nominal system and arranging them into a standard Δ-M structure. Subsequent determination of p for this structure along with the small-gain theorem enables a robustness assessment to be made for the system under study. Two procedures are given which enable reduction of a switching regulator system to Δ-M form. The first considers uncertainties to exist only in inductor and capacitor values. The other extends the formulation to encompass resistance uncertainties as well. An example is given of a regulator design for which an assessment is made of the allowed component tolerances which guarantees a lower limit of the phase margin View full abstract»

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  • Application of sliding observer to sensorless permanent magnet synchronous motor drive system

    Page(s): 532 - 536 vol.1
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    This paper proposes a new control method for shaft sensorless permanent magnet synchronous motor drive systems. The rotor position and speed are estimated by using a sliding observer with only stator voltage and current measurements. The observer structure and its design method are discussed. The simulation results of the overall system are presented to demonstrate the effectiveness of the approach View full abstract»

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  • Performance requirements for power MOSFET models

    Page(s): 69 - 76 vol.1
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    The power MOSFET model performance required for accurate waveform simulation is evaluated for most converter circuits. Three models are thoroughly evaluated through C-V plots, gate charge plots, and converter data. A procedure is given for evaluating any proprietary model using data book information with three simple simulations View full abstract»

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  • Piezoelectric transformer operating in thickness extensional vibration and its application to switching converter

    Page(s): 585 - 589 vol.1
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    A new type of piezoelectric transformer (PT) power converter incorporating the ZVS technique is presented. A combination of the ZVS technique and the PT successfully achieves higher efficiency. For low output voltage, using half-bridge rectifier stage, the converter achieved 72% efficiency, at Vin=80 V, Vo=11.8 V, and Po=5 W. For medium output voltage, using full-bridge rectifier stage, the converter achieved 83% efficiency at Vin=80 V, Vo=40 V, and Po=10.7 W View full abstract»

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