Inverter Part Research Articles

Implementation of a single-phase AC/AC converter based on neutral-point-clamped topology

A single-phase ac/ac converter based on neutral-point-clamped scheme is proposed to perform unity input power factor and to provide a stable ac voltage to the critical loads. The ac/dc rectifier part is controlled to generate a unipolar pulsewidth modulation (PWM) waveform on the ac terminal by using four power switches with voltage stress of half the dc-link voltage. The carrier-based current control scheme is employed in the inner control loop to track the line current command. To regulate the dc bus voltage, a proportional-integral (PI) control is adopted in the outer control loop. The dc/ac inverter part of the system with four power switches is employed to generate a stable and clean sinusoidal output voltage to the critical load. The instantaneous current control scheme is used to track the output voltage command. To verify the effectiveness of the proposed control algorithm, the simulation and experimental results based on a laboratory prototype were implemented and discussed.

Integrated Design Approach for Medium Power Inverters Optimized for EMC and Thermal Performance

Today’s stale of the an power electronics system require the design engineers ro employ an integrated approach, utilizing IGDTs. heat sink, capacitors and gate driver circuits at their peak performance. While functionality is of course alw ays important, the problem of manufacturahility, cost and electromagnetic compatibility (EMC) are elements that have to he kept into account.In this paper the authors show how electromagnetic interference caused by power electronic circuits can be reduced by the minimization of the total inductance commutation loop of an inverter leg. At the same time special attention is due to the compactness of the inverter especially as regard to the heat sink and the thermal issues. The goal is a proper design and construction of the inverter so tackling EMI directly at the source where most EMI is generated. In this way application of expensive EMI filters can be avoided. Moreover the analysis of the thermal behavior is shown. In order to reach this goal a proper selection and design of the inverter parts have been made and implemented. Specifically, a prototype of converter has been developed to reach the maximum reduction of the stray inductance commutation loop and the maximum compactness using the actual available technology. Experimental results are given to show the validity of this approach.

An eigenvalue method of undetermined coefficients for solving linear rational expectations models

Abstract Consider a structural linear rational expectations model of the form ∑ i =0 p ∑ j =− r i A i , j E t − i y t − j =∑ i =0 q B i e t − i + z t , where y t is an m ×1 vector of endogenous variables, e t ∼ IID (0, Σ e ) is an m ×1 vector of structural disturbances, and z t is an n ×1 vector of exogenous variables. Under conditions stated in the paper, the model has the unique reduced-form solution, y t =∑ i =1 p Φ i y t − i + ξ t +∑ i =1 q Θ i ξ t − i +∑ i =0 ∞ Ξ i z t + i , where ξ t ∼ IID (0, Σ ξ ) is an m ×1 vector of reduced-form disturbances. The paper derives an analytical eigenvalue method for computing the autoregressive, moving-average, and exogenous parts of the reduced-form solution of a model in the above form. The method routinely handles expectations conditional on several different dates and singular leading coefficient matrices and produces an invertible moving-average part. The paper also derives four new theorems on the existence of a unique solution.

Conceptual considerations on PV systems composed of AC modules

AC module technology has become popular and a number of AC module types are commercially available. Although their specifications are clear, it seems that their technological meaning has not yet been well developed. Therefore, the authors tried to create the total concepts of PV systems composed of AC modules. They are abbreviated AC module-composed PV system or ACM-PV. In the paper, the possible structural configurations of simple AC modules and battery integrated ones are classified in principle. System categories are also classified to show their total concept. Necessary electrical terminals and interfaces, voltage matching method between inverter and PV part, and AC module testing methods are also discussed.

Nonparametric approach to Wiener system identification

A Wiener system, i.e., a system consisting of a linear dynamic subsystem followed by a memoryless nonlinear one is identified. The system is driven by a stationary white Gaussian stochastic process and is disturbed by Gaussian noise. The characteristic of the nonlinear part can be of any form. The dynamic subsystem is asymptotically stable. The a priori information about both the impulse response of the dynamic part of the system and the nonlinear characteristics is nonparametric. Both subsystems are identified from observations taken at the input and output of the whole system. The kernel regression estimate is applied to estimate the invertible part of the nonlinearity. An estimate to recover the impulse response of the dynamic part is also given. Pointwise consistency of the first and consistency of the other estimate is shown. The results hold for any nonlinear characteristic, and any asymptotically dynamic subsystem. Convergence rates are also given.

Characteristics of electric power transmission on high-frequency inverter having distributed constant line at load side

An induction heating system aimed at improving the characteristics of high-frequency power supplied from the high-frequency, inverter to the parallel resonant load circuit is proposed, and its transmission efficiency is studied. In this system, high-frequency power can be supplied by lowering the effect of the inductance component accompanied by wiring between the inverter circuit and the resonant load circuit. Impedance matching between the inverter and the resonant circuit and high-efficiency power transmission from the inverter to the load circuit are possible. If a flexible coaxial cable is used as the distributed constant line, it is easy to cope with the case in which comparative distance exists between the inverter part and the heating part or the case in which the heating part is moved. >

SOME THEORETICAL INSIGHTS INTO RECENT CONTROL DESIGN ALGORITHMS

Abstract Internal Model Control (IMC) design procedure is known to offer valuable advantages over classical control methods, especially for robust controller design. The Perfect Controller is defined using the well-known classical PID algorithm and its equivalence to IMC. After the definition of the Perfect Controller the IMC filter tuning parameter, which is used to maintain robustness, is obtained as a result of reparametrization of the classical PID control algorithm and factorization of the model. Through factorization, invertible part of the model is used directly in defining the perfect controller and the noninvertibility effects of the model are lumped into the new IMC tuning parameter. Closed loop IMC controller design is obtained with appropriate plant parameter uncertainty representation. Theoretical foundation for the transition from classical PID design to IMC design is analyzed using simple common chemical process models.