Stationary frame current regulation of PWM inverters with zero steady-state error

Current regulators for AC inverters are commonly categorized as hysteresis, linear PI, or deadbeat predictive regulators, with a further sub-classification into stationary ABC frame and synchronous d-q frame implementations. Synchronous frame regulators are generally accepted to have a better performance than stationary frame regulators, as they operate on DC quantities and hence can eliminate steady-state errors. This paper establishes a theoretical connection between these two classes of regulators and proposes a new type of stationary frame regulator, the P+Resonant regulator, which achieves the same transient and steady-state performance as a synchronous frame PI regulator. The new regulator is applicable to both single-phase and three phase inverters.     

Obtaining medial responses from steerable filters

In building up a multiscale, medial axis representation, the generation of medial responses from a set of boundary responses at multiple scales can be a computationally intensive process. Polar separable medial weighting kernels are applied to the computation of medial responses. An approximate method for the synthesis of rotated kernels is proposed. Because of the need to not only rotate, but to displace boundary responses by an amount dependent on the image scale, the traditional steerable filter approach must be modified to yield correct medial responses. Comparisons between integral evaluation and the adaptive filtering approximations show that 100-fold increases in modestly sized images at a single scale are possible. The error in the approximation is insignificant     

z transfer functions of sampled-data control systems with a discontinuous error signal

Sampled-data control systems, of which the open-loop transfer function is such that the corresponding impulse response is discontinuous at the origin, cannot be studied with the usual z formula. The z transfer function of such systems is established when it can be assumed that there is no instantaneous transmission, or when the sampler is not a usual Dirac sampler.     

The measurement of the charge residual for CCD transfer using impulse and frequency responses

By developing a model for the impulse response of a single phase CCD a simple equation is derived which relates the ratio of the first two pulses of the impulse response to the charge residual ?. When this is extended to practical multiphase structures it is shown that this equation is independent of the number of clock phases used in a CCD. Using Z transforms an expression for the frequency response of a CCD is derived in terms of ?. Values for the charge residual are obtained by experimental measurement of impulse and frequency responses and these are compared to test the validity of the model used.     

Adaptive algorithms with nonlinear data and error functions

The tools of nonlinear system theory are used to examine several common nonlinear variants of the LMS algorithm and derive a persistence of excitation criterion for local exponential stability. The condition is tight when the inputs are periodic, and a generic counterexample is demonstrated which gives (local) instability for a large class of such nonlinear versions of LMS, specifically, those which utilize a nonlinear data function. The presence of a nonlinear error function is found to be relatively benign in that it does not affect the stability of the error system. Rather, it defines the cost function the algorithm tends to minimize. Specific examples include the dead zone modification, the cubed data nonlinearity, the cubed error nonlinearity, the signed regressor algorithm, and a single-layer version of the backpropagation algorithm     

Off-line uninterruptible power supply with zero transfer time usingintegrated magnetics

An offline uninterruptible power supply (UPS) or emergency power system with zero transfer time is presented. The principal application is to personal computers and systems. The power transformer, a triport-like transformer, acts as an inverter and as a voltage stabilizer with no external loading coil. It is made with commercial EI scrapless laminations. The battery charging circuit is integrated into the transformer and improves the dynamic output response during line-mode operation. The result is robust, short-circuit-proof equipment with harmonic distortion of lower than 3%, a static output stability better than 1.5%, and a very high reliability     

Simple-to-evaluate error probabilities for impulse radio UWB multiple access systems with pulse-based polarity randomization

Simple-to-evaluate and accurate bit error probabilities are presented for impulse radio ultra-wideband multiple access systems that use time hopping sequences with pulse-based polarity randomization and binary phase shift keying modulation. Simplified improved Gaussian approximation is used. It is shown that despite having the same processing gain, which is the multiplication of the number of frames per bit and chips per frame, different combinations of the parameters result in different performances. The theoretical results are validated by Monte Carlo simulations.     

Synthesizing transfer functions with two grounded pentodes

Two grounded, inverting amplifiers, interconnected by resistors and capacitors, can synthesize an open-circuit voltage gain equal to any ratio of real polynomials in the complex frequency variable. The amplifiers can have finite gains (greater than unity), finite input conductances, and finite output resistances.     

Approximation of multivariable functions by M-D transfer functions with separable denominator

The approximation of a given function by a rational function has been considered extensively by mathematicians. A particular result has been stated by Walsh that the best approximation of a given analytical function is one which interpolates the given function at several properly chosen points. In this paper, transfer functions of multidimensional digital filters with separable denominator are used for the approximation of given multivariate functions. It is shown that the result of Walsh can be generalized in a straightforward manner. By an example it is illustrated how the new result can be applied to, e.g., the order reduction of a higher-order system. In the conclusion we state the usefulness and the limitation of the result.     

Realization of second-order transfer functions with switched-capacitor networks

A flexible switched-capacitor synthesis procedure realizing second-order z-domain voltage-transfer functions is given. The active networks generated by this technique consist of capacitors, switches and operational amplifiers.     

Reconstruction of multilayered lossy dielectrics from one-sidedplane wave impulse reflection responses: the bistatic case

Motivated by numerous scattering problems where the media is lossy and yet can only be investigated from a single side, the authors discuss algorithms for reconstructing a lossy, stratified dielectric from one-sided plane wave impulse reflection responses. Novel features of these algorithms include: 1) solving the lossy media problem using only one-sided reflection response data; 2) exploiting oblique probing angles; 3) having origins in digital signal processing (DSP) theory; 4) employing fast algorithms that have been modified to solve the forward scattering problem; and 5) solving the scattering problems exactly, including accounting for multiple reflections. A new algorithm is introduced that reconstructs such a media from one-sided transverse electric (TE) and transverse magnetic (TM) impulsive plane wave reflection responses from a single oblique angle. The oblique-probing angle necessitates a bistatic measurement configuration. New probing constraints are developed for a previously presented algorithm based on probing at two angles of incidence. Algorithm stability and data correction are addressed. Numerical examples illustrate the new algorithm in synthesizing the media transient response and reconstructing the media     

Sample functions of a Gaussian process cannot be recovered from their zero crossings (Corresp.)

The types of ambiguities that preclude the possibility of recovering the sample functions of a Gaussian process from their zero-crossings are illustrated by a simple example.     

Extraction of teletext channel information from measured complexand in-phase impulse responses at baseband and their significance

The technical advantages of measuring complex impulse responses rather than the in-phase component of broadcast teletext channels and the extraction of channel information from real impulse response measurements and its limitations are described. A number of illustrative examples are provided. It is concluded, after discussion, that measurements of channel complex impulse responses are necessary, in spite of extra cost, so that suitably flexible and general computer simulation design and performance studies of broadcast teletext systems can be made     

Absolute error rate-distortion functions for sources with constrained magnitudes (Corresp.)

The explicit evaluation of the absolute error rate-distortion function has been obtained previously for a class of i.i.d, sources with probability densities supported on the entire real line. The technique is extended to various i.i.d, sources with densities supported on a proper subset of the real line, such as uniform and one-sided exponential densities. Comparisons of these rate-distortion functions with their Shannon lower bounds are also given.     

Insensitive voltage-mode and current-mode filters with easily modifiable transfer functions

Two configurations for 2^nd order current-mode filters are introduced. The circuits, which exhibit low values for their active and passive sensitivies are implemented from two current conveyors. They are easily cascadable because they exhibit zero input impedance. Two voltage-mode implementations are then deduced from them. Depending on the passive components used, the circuit will be either a 2^nd order or a 3^rd order filter. Both the current-mode and voltage-mode implementations are characterized by easily modifiable transfer functions, without affecting ₀ and Q.SPICE simulation results, which confirm the theoretical analysis, are given and discussed for current conveyors implemented in a translinear form.     

Partial fraction expansion of transfer functions with multiple quadratic poles

The partial fraction expansion method presented is short and straightforward, and the matrix formulation is easily programmed for computation. The method is applicable without restriction to rational functions with multiple real or quadratic poles.     

High-speed coupled-cavity injection grating lasers with tailored modulation transfer functions

The modulation transfer function can be changed from broad-band to high frequency narrow-band by using a coupled cavity injection grating laser design. Higher order photon-photon resonances are utilized to tailor the modulation function well beyond the relaxation frequency.     

Cross-correlation antenna systems with modified principal solution spatial frequency transfer functions

The principal solution type of spatial frequency transfer function (SFTF) for a linear antenna system, e.g., line source or linear array, is constant (flat) over its entire spatial frequency (SF) passband and drops abruptly to zero at the edges of the band. Such a SFTF is obtainable with cross-correlation (multiplicative) techniques. The associated power pattern, of thesin (Lu)/Lutype, has high sidelobes diminishing asymptotically asu^{-1}. Moreover, the weighting distribution for the line source has an inverse taper with end point singularities. A modified principal solution SFTF, flat over most of the SF passband but with a smoothly varying transition function of the quadratic-linear-quadratic type at the edges of the passband is introduced. This engenders a power pattern whose sidelobes diminish asymptotically asu^{-3}instead ofu^{-1}. The line source weighting distributions, moreover, are continuous and free of singularities, making physical realizability no longer a problem.