Sampled‐data poles,zeros, and modeling for current‐mode control

Exact and approximate sampled‐data models in closed forms are derived for switching DC–DC converters under peak/valley current‐mode control. The corresponding sampled‐data poles and zeros in closed forms are also derived. The location and stability conditions of the poles and zeros, boundary conditions of subharmonic instability, and nulling of the audio‐susceptibility are also derived. It is proved that the stable operating range of the source voltage is linearly proportional to the ramp slope. The sampled‐data models agree with previous experiment results and accurately predict the subharmonic instability. The different view from the sampled‐data model about the number and stability (minimum phase) of pole and zero does not necessarily invalidate the traditional continuous‐time averaged model. However, this different view gives better prediction about converter dynamics and is useful for the analog or digital controller design for DC–DC converters. Copyright © 2011 John Wiley & Sons, Ltd.     

Low-pass filters with maximally flat magnitude beyond the origin and arbitrary transmission zeros

An analytical procedure for generation of a special type of critical monotonic magnitude characteristic, having maximal flatness at a given frequency ω₀ beyond the origin, with arbitrary transmission zeros, is presented. Compared with the known filters with maximally flat magnitude at the origin and the same transmission zeros, the new filters show distinct improvement in the cutoff performance.     

Quantitative T 2 measurement of a single voxel with arbitrary shape using pinwheel excitation and CPMG acquisition

Objective The aim of this study is to present a new approach for making quantitative single-voxel T ₂ measurements from an arbitrarily shaped region of interest (ROI), where the advantage of the signal-to-noise ratio (SNR) per unit time of the single-voxel approach over conventional imaging approach can be achieved. Materials and methods Two-dimensional (2D) spatially selective radiofrequency (RF) pulses are proposed in this work for T ₂ measurements based on using interleaved spiral trajectories in excitation k-space (pinwheel excitation pulses), combined with a summed Carr–Purcell Meiboom–Gill (CPMG) echo acquisition. The technique is described and compared to standard multi-echo imaging methods, on a two-compartment water phantom and an excised brain tissue. Results The studies show good agreement between imaging and our method. The measured improvement factors of SNR per unit time of our single-voxel approach over imaging approach are close to the predicted values. Conclusion Measuring T ₂ relaxation times from a selected ROI of arbitrary shape using a single-voxel rather than an imaging approach can increase the SNR per unit time, which is critical for dynamic T ₂ or multi-component T ₂ measurements.     

远极比4／24电机绕组方案探讨

提出极比为4／24的双速电机的两种绕组方案：单绕组双速、双绕组双速。其中,单绕组变极方案在每槽导体数相同的条件下成功解决了因变前极极对数为3倍数,变后极极对数非3倍数而导致的变后极三相不对称问题。对两种方案进行了试验与分析,得出实践结论。     

Sallen and key-type RC-active filters with complex transmission zeros

A second-order minimum-phase RC-active filter with complex transmission zeros is presented. It employs one operational amplifier and is based on a well-known Sallen and Key resonator. By including an additional difference amplifier a second-order all-pass circuit is derived. Both networks have free network parameters which can be used for minimizing the sensitivities of the Q-factors of the poles and zeros.     

Performance prediction of a hybrid‐excitation synchronous machine with axially arranged excitation poles and permanent‐magnet poles

This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033     

Rating of cables on riser poles, in trays, in tunnels and shafts-areview

This paper reviews rating of cables installed in air. The following cable installations are investigated: (1) cables on riser poles, (2) cables in open and closed trays, (3) cables wrapped in fire protection covers, (4) cables in horizontal tunnels, and (5) cables in vertical shafts. The rating of cables in these installations is computed by solving energy balance equations for the unknown surface temperature with a given conductor current. In ampacity computations the conductor current is adjusted iteratively until permissible cable conductor and surface temperatures are achieved. It is shown in the paper how the same energy balance equations can be used to compute the ratings of all the above cable installations     

Salient poles synchronous machine simulation,validation and inductance determination procedure

In this paper, a computer simulation of the salient poles synchronous machine (SPSM) is presented. This simulation employs a modeling based on the machine self and mutual inductance curves, determined from a methodology, which is also presented here. This methodology applies the volt–ampere method in a first experimental stage, where the machine currents and voltages are oscillographied, with its digitalized data storage. In a second stage, stored data receive a mathematical manipulation. The simulated results are confronted with the experimental currents and voltages measured in tests for purposes of validation of the SPSM modeling as well as the inductance determination methodology. Copyright © 2011 John Wiley & Sons, Ltd.     

混合磁极式的混合励磁永磁同步发电机仿真

为了研究混合磁极式的混合励磁永磁同步发电机转子上既有永磁体、又有励磁绕组的运行性能,建立了混合磁极式的混合励磁永磁同步发电机的基本方程;根据该电机的转子结构及定子绕组的实际连接方式和空间分布情况,分析了模型中电感参数及永磁体在其他回路中产生的磁链的特点,并给出其表达式;采用有限元法计算各参数表达式中的系数,能准确考虑磁极形状及永磁体的作用,利用数值方法对该电机的性能进行仿真.在1台混合磁极式的混合励磁永磁同步发电机样机上进行了实验,仿真结果和实验结果吻合较好,验证了仿真模型的正确性和参数计算的准确性.     

High frame-rate, 3-D photorefractive holography through turbidmedia with arbitrary sources, and photorefractive structuredillumination

In this paper, we briefly review our work on low-coherence photorefractive holography and report on the current state of the art. We present what is, to the best of our knowledge, the fastest-ever three-dimensional (3-D) imaging system and present results obtained with imaging at 470 frames/s (fps). We demonstrate the versatility of photorefractive holography using various sources, including LEDs, high-power diode arrays, and a novel, all solid-state broad-band laser. We present preliminary results obtained by combining the technique of structured illumination with photorefractive holography for the first time. We demonstrate that this novel holographic optical sectioning technique may be implemented for both reflection and fluorescence imaging     

The role of zeros in the performance of multiinput, multioutputfeedback systems

A review of the early history attached to the idea of zeros for systems with multiple inputs and outputs is provided. A discussion of the consensus definitions for such zeros is given together with the ways in which they are involved in control thinking and control applications. A control zero principle and a control pole principle explain the intuitive way in which zeros and poles influence the performance of feedback systems. These are presented in the multivariable case by means of a pair of new results, this provides a framework to unify the overall presentation. Zeros at infinity are introduced; the causality of controllers is fitted onto place; and developments in time-varying zeros, nonlinear zeros, and generic zeroes are described     

Analysis and design of discrete‐time charge domain filters with complex conjugate poles

This paper proposes a discrete‐time charge domain filter that achieves complex conjugate poles in the transfer function of the filter. To achieve complex conjugate poles, local feedbacks are inserted around two successive discrete‐time integrators. The feedback path is implemented through a transconductance cell which applies a continuous time current into the integrators. Analytical models have been proposed to approximate the behavior of the filter. These models confirm that the structure is capable of realizing complex poles and thus can be used to synthesize any type of filter structures such as Butterworth, Chebysheve, etc. To show the effectiveness of the proposed architecture, Butterworth filters of order 2 and 4 operating at 50MS/s are designed and implemented in 180‐nm CMOS technology with 1.8‐V power supply. The effect of circuit nonidealities on the performance of the filter is analyzed and verified through simulations. Simulation results show that a conventional charge domain filter can be simply extended to implement complex conjugate poles while the noise and linearity performance of the filter are also improved. Copyright © 2016 John Wiley & Sons, Ltd.     

Calculation errors for the magnetic conductivity of an electromagnet with truncated pyramid-shaped poles

Abstact  The results of a study on an electromagnet with two coils in an E-shaped magnetic tube (tubing) are described. The 3D problem is solved using methods of partial volume summation and calculation poles. Original Russian Text ? O.B. Bul’, 2009, published in Elektrotekhnika, 2009, No. 1, pp. 56–66.     

Lowpass approximations of a constant amplitude with arbitrary phase and delay

A review is made of recent developments to the simultaneous lowpass approximation problem of amplitude, phase and delay. the closed from solutions (reciprocal and non-reciprocal) are expressed in terms of the arbitrary phase and delay polynomials (APD).     

On the problem of filters with arbitrary amplitude and phase constraints

A simplified method—based on the concept of reflection filters—is presented for designing linear phase filters with arbitrary amplitude to phase constraints. This method starts with transfer functions with 2: 1 amplitude to phase constraints, and through varying the recurrence relation of the polynomials involved, transfer functions with more selective amplitude are obtained.     

单相电能表实负荷校验、虚负荷校验电路比较及误差分析

分析了单相民能表实负荷校验、虚负荷校验的校验线路、特点及校验中引起的误差，并介绍了一种实用的校验线路。