液力变矩器反转工况的计算方法与试验验证

军用履带车辆采用液力传动后，需要解决车辆的辅助制动， 本文在一元束流理论基础上， 利用液力变矩器无因次方程， 研究了综合式液力变矩器反转工况的计算方法， 并利用某军用履带车辆的液力变矩器进行了计算与试验， 依据试验结果对利用液力变矩器反转工况制动的可行性进行了分析．     

寄生电容对零电压过渡PWM电路影响及对策

本文介绍了零电压过渡ＰＷＭ软开关电路的工作原理，详细分析了寄生电容参数对电路工作过程的影响，并提出了解决的方法。实验证实了本文的分析。     

板焊式变换炉的设计

变换炉是煤气化装置中的重要设备之一,操作工况比较苛刻,文章就某大型煤气化装置中板焊式变换炉的材料选择、结构设计、制造、检验中遇到的问题进行探讨,并给出最终合理的解决方案。     

Parallel single-phase ac–dc–ac shared-leg converters: Modelling,control and analysis

Reversible single-phase to single-phase dc-link converters are proposed and analyzed in this paper. They are composed of paralleled rectifiers and inverters sharing one or two legs with one or two dc-links. Modelling and a control strategy of the systems including circulating currents are developed. Compared to the conventional single-phase to single-phase dc-link converter, the proposed topologies permit to reduce: (i) the current and power ratings of the power switches, (ii) the harmonic distortion, and (iii) the dc-link capacitor losses. Additionally, the semiconductor losses of the proposed converters are smaller than that of the conventional one. Simulated and experimental results are also presented to demonstrate the viability of the proposed circuits.     

转炉除尘水水质稳定方法改进的探讨

抚顺新钢铁有限责任公司有45 t转炉3座,一次除尘是湿法除尘,实际运行过程中出现过较为严重的问题,管路堵塞,系统结垢,给生产造成很大的影响,经系统研究并采取具体措施,系统问题得以彻底的解决.文中主要介绍了针对实际问题结合炼钢工艺特点,进行分析探讨和采取的措施.     

Brief of the technology using sliding gate for slag stopping during converter tapping in the steelmaking plant of Baoshan Iron & Steel Co.,Ltd.

The sliding gate used to stop slag during converter tapping is similar to the control of slide gate in ladle,with the sliding gate device installed outside the BOF tapping hole tip.Owing to the quick opening and closing(in 0.5 s) of the sliding gate,it can not only effectively stop the pre - slag and post - slag during converter tapping but also automatically judge and stop slag with the help of AMEPA slag detecting and PLC control technology.Currently it is regarded as the best process to stop slag during converter tapping.     

托普索S—100型合成塔顶盖泄漏原因及对策

分析托普索Ｓ－１００型合成塔顶盖双锥自紧式组合密封使用柔性石墨软密封的泄漏原因，计算制定了更换为铝箔垫的预紧压力和方法。     

Principle of designing slope compensation in PFC Boost converter

Due to wide input fluctuation with line frequency of 50 Hz, power-factor-correction (PFC) Boost converters tend to exhibit fast-scale instability over time domain. The traditional remedy is to impose slope compensation so as to weaken or eliminate this instability. A theoretical principle on the implementation of slope compensation signal is still lacking. Empirical design will induce over compensation frequently, resulting in a large decrease of power factor. In order to tackle this issue, by constructing the discrete-time iterative map of the PFC Boost converter from the viewpoint of bifurcation control theory of nonlinear systems, consequently, the criterion of critical stability for the PFC circuit can be established. Based on this stability criterion, appropriate design of slope compensation can be achieved. Our work indicates that 3 main circuit parameters (i.e. switching cycle, output reference voltage and inductor) determine the effective amplitude design of the slope compensation signal. The results, validated by a large quantity of analytical and numerical studies, show that appropriate slope compensation can be effective in weakening (or controlling) fast-scale bifurcation while maintaining a rather high input power factor.     

Experimental verification of a dynamic voltage restorer capable of significantly reducing energy‐storage element requirements

This paper deals with a dynamic voltage restorer (DVR) characterized by installing the shunt converter at the load side. The DVR can compensate for the load voltage when a voltage sag appears in the supply voltage. An existing DVR requires a large capacitor bank or other energy‐storage elements such as double‐layer capacitors or batteries. The DVR presented in this paper requires only a small DC capacitor intended for smoothing the DC‐link voltage. Moreover, three control methods for the series converter are compared and discussed to reduce the series‐converter rating, paying attention to the zero‐sequence voltages included in the supply voltage and the compensating voltage. Experimental results obtained from a 200‐V, 5‐kW laboratory system are shown to verify the viability of the system configuration and the control methods. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 73–82, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20460     

A Hybrid Genetic Algorithm for Selective Harmonic Elimination PWM AC/AC Converter Control

This paper presents an optimal solution for eliminating pre-specified orders of harmonics from the output waveform of AC/AC converter. The main challenge of solving the associated nonlinear equations, which are transcendental in nature and therefore have multiple solutions, is the convergence and therefore an initial point selected considerably close to the exact solution is required. The paper discusses an efficient hybrid real coded genetic algorithm (HRCGA) that reduces significantly the computational burden resulting in a fast convergence. An objective function describing a measure of effectiveness of eliminating selected orders of harmonics, while controlling the fundamental is derived and a comparison of different operating points is reported. It is observed that the modulation index can reach unity value. The theoretical findings are verified through simulation results using the PSIM software package.