直流稳压电源标准装置的研究

论述了建立直流稳压电源标准装置的基本步骤,主要讨论其数学模型的建立、不确定度的分析、重复性与稳定性验证的评价过程,并通过实验数据分析建立了直流稳压电源的二级计量标准.     

直流高压标准装置国际近况

简单介绍电磁计量领域关键比对数据库中直流高压参数标准装置-直流高压分压器的原理,分析了电阻发热、电晕放电以及绝缘支架漏电对直流高压分压器的影响,归纳总结目前国际上先进计量机构的直流高压标准装置的结构型式以及在校准时引入的不确定度来源。给出了直流分压器达到10-6量级的必要条件。     

高负载能力电压电流标准源的研究

在多年计量检测经验的基础上,从电工仪表分析,以及仪表检测的要求入手,介绍一种高负载能力电压电流标准源的具体实现过程、工作原理,以及适应检测工作的各种设计等。最终实现模拟式、数字式电压、电流仪表检测目的。     

State primary standard for the unit of direct current,the ampere

The new state primary standard for direct current is described, together with its block diagram and accuracy parameters. The accuracy of realization is improved by two orders of magnitude (standard deviation 5–10^–8, residual systematic error 2·10^–7). The range of current realization in the standardis extended to 10^{–16 A}.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 3–4, January, 1995.     

磁热效应的直接测量及装置

磁热效应的测量有间接测量和直接测量两种方法。本文在比较两种测量方法各自特点的基础上,重点综述了直接测量装置的种类及特点;指出直接测量装置在室温磁制冷技术研究中的重要作用。     

New equipment for measuring the effective value of a voltage over a wide frequency range

Conclusion The theoretical and experimental investigations of the methods and equipment for precise measurements of the effective values of voltages from 0.1 to 150 V with errors of 0.01–0.3% provided for the checking and testing of manufactured and newly developed broadband voltmeters and calibrators for precision measurements of the effective values of voltages.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 55–59, May, 1970.     

A current ripple reduction of a high-speed miniature brushless direct current motor using instantaneous voltage control

High-speed miniature brushless direct current motor (BLDCM) is used in robots and medical applications because of its high-torque and high-speed characteristics. When compared with the general BLDCM, a high-speed miniature BLDCM has a low electrical time-constant. The current and torque ripple are very high when compared with the conventional pulse-width modulation (PWM) control scheme in the conduction period because of the inherent electrical characteristics. The authors propose a simple instantaneous source voltage and phase current control for torque ripple reduction of a high-speed miniature BLDCM. To reduce the switching current ripple, instantaneously controlled source voltage is supplied to the inverter system according to the motor speed and the load torque. In addition, a fast hysteresis current controller can keep the phase current within a limited band. Computer simulations and experimental results up to 40 000 rpm show the effectiveness and verification of the proposed control scheme.     

Influence of substrate direct current bias voltage on microcrystalline silicon growth during radio-frequency magnetron sputtering

Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared on glass, aluminum-covered glass and Si wafer substrates at various substrate bias voltages (V_sb) between -400 and +50 V, and the influence of V_sb on their structural properties was investigated. The crystallinity (crystalline volume fraction and crystallite size) of the μc-Si:H films deposited on glass remained unchanged with respect to V_sb. For μc-Si:H films deposited on aluminum within the V_sb range of -20 to +50 V, the crystallinity also remained unchanged and showed the same crystallinity as that of the films deposited on glass substrate. However, the crystallinity of the μc-Si:H films deposited on aluminum-covered substrate was reduced as V_sb decreased from -20 to -100 V, and the film at V_sb=-400 V was completely amorphous.