摘 要
本文介绍了一种现阶段能量天平磁场系统稳流源的设计方案。该稳流源以串联反馈式恒流电路为核心构成基本稳流电路，同时根据负载的变化设计了特殊的调整管压降反馈补偿电路，解决了正常工作时磁场线圈由于通电发热电阻增大导致基本稳流电路调整管漏源电压降低使得输出电流存在明显漂移的关键问题。
文章首先介绍了现阶段能量天平磁场系统稳流源的基本构成原理并推导了理想电流公式，然后详细分析了影响电流稳定度的内部因素和外部因素并最终确定了该稳流源设计的关键部件——基准电压、采样电阻和误差放大器的选型和设计依据，同时对关键辅助电路，包括主电源电路、辅助电源电路、电流测量电路和保护与补偿电路的设计思路进行了详细介绍。针对稳流源负载线圈由于通电发热电阻增大而导致基本稳流电路调整管漏源电压降低使得输出电流存在明显漂移的问题，设计了特殊的调整管压降反馈补偿电路，解决了传统稳流源调整管压降控制方法在高稳定度稳流源设计中存在的缺陷和不足。
文章主要论述了三个特殊的应用和设计，一是将直流电压标准732B作为基准电压应用于磁场系统稳流源基本稳流电路中，使得稳流源正常工作时基准电压的稳定性达到10-8量级每小时；二是设计了一个低负荷系数的大功率采样电阻并通过实验证明了其负荷稳定性达到10-8量级每30分钟；三是设计了特殊的稳流源调整管压降反馈补偿电路，解决了由于磁场线圈通电发热造成电流存在明显时间漂移的问题，大大提高了电流稳定性。基于上述三项主要工作，最终设计出满足现阶段能量天平磁场系统要求的稳流源。
测试结果表明，正常工作时当磁场线圈电阻增大约145Ω时，能量天平磁场系统稳流源调整管压降仅下降约0.4V，30分钟内电流变化相对标准差为2.0×10-7，电流稳定度为2.4×10-7，达到了设计要求。
关键词能量天平 磁场稳流源 基准电压 采样电阻 调整管压降控制
Abstract
A design scheme of constant current source for the magnetic field system of the Joule Balance at prent is introduced in this paper. The fundamental circuit of this constant current source is bad on the rial feedback constant current circuit. At the same time, an ingenious voltage drop feedback compensation circuit for the adjustment tube is devid due to the variation of the load, which solves the key issue of apparent drift of the output current becau of the decrea of voltage between the drain and the source electrode of the adjustment tube due to the increasing of the resistance of the magnetic field coil in the cour of regular working hours.
In this paper, the basic structure principle of the constant current source for the magnetic field of Joule Balance is firstly introduced and the ideal formula is deduced. Afterwards, the external and the internal factors that influence the stability of the current are analyd respectively and the lection and design basis of the critical component of the constant current source including reference voltage,
sample resistor and error amplifier are determined ultimately. Meanwhile, the design concept of the auxiliary circuit including main power circuit, auxiliary power circuit, current test circuit and protect & compensation circuit are prented in detail. Considering apparent drift of the output current due to the decrea of voltage between the drain and the source electrode of the regulator caud by the incread resistance of the constant current source’s load coil, a special feedback compensation circuit for the regulator is devid. This design solves the limitation and deficiency of traditional control methods for maintaining the voltage of the regulator ud in the design of high precision constant current source.
Three special application and design are mainly discusd in this paper. Firstly, DC Voltage Standard 732B is applied in the fundamental stable current circuit of the constant current source for the magnetic system, and the stability of the reference voltage in circuit reaches 10-8 per hour when the constant current source is working. Secondly, a sample resistor of low load coefficient and high-power is devid and its stability reaches 10-8 per 30 minutes,
which has been proved by experiment. Thirdly, a special feedback compensation circuit for the voltage between the regulator of the constant current source is devid, which solves the problem of apparent drift along with time due to the power heating of the magnetic field coil, and the stability of t
he current is greatly improved. Bad on the three critical techniques above, a constant current source satisfying the magnetic field system of the Joule Balance at prent has been achieved.
The test results show that the voltage between the drain and the source electrode of the regulator in the constant current source for the Joule Balance only decreas about 0.4V when the resistance of the magnetic field coil increas 145Ω during the normal working condition. In 30 minutes, the relative standard deviation of the current is 2.0E-7, and the stability is 2.4E-7, which attains the design requirements.
为虎作伥Key words Joule Balance Constant current source for magnetic field Reference voltage Sample resistor Voltage controlled between regulator
目 录
第1章 绪论 (1)
1.1课题研究的背景及意义 (1)
1.2能量天平磁场系统稳流源概述 (4)
1.2.1能量天平磁场系统稳流源的特殊性 (5)
成长足迹
1.2.2能量天平磁场系统稳流源的技术指标 (5)
1.3直流稳流源的研究现状及发展趋势 (6)
1.3.1直流稳流源国内外研究现状 (6)
1.3.2高稳定度直流稳流源综述 (7)
1.3.3直流稳流源的发展趋势 (9)
艺术文字
1.4课题主要研究内容及创新点 (9)
1.4.1主要研究内容 (9)
1.4.2创新点 (9)
赋的读音1.5本章小结 (10)
第2章 总体设计与基本原理 (11)
2.1总体设计 (11)
2.2核心电路原理与分析 (12)
2.2.1基本原理 (12)
2.2.2电流稳定度的影响因素分析 (13)
2.3本章小结 (15)
第3章 基本稳流电路 (16)
3.1基准电压 (16)
3.1.1基准电压概述 (16)
3.1.2基准电压的选型及测试 (18)
3.2采样电阻 (22)
3.2.1精密电阻概述 (22)
3.2.2低负荷系数采样电阻的研制 (24)
3.3误差放大器 (28)
六倍体
3.3.1开环增益 (28)
3.3.2等效漂移和噪声 (28)
3.4调整管 (30)
3.5关键辅助电路 (31)
3.5.1电流测试电路 (31)
3.5.2保护与补偿电路 (32)
当今时代的主题
3.5.3 主电源电路 (33)
3.5.4辅助电源电路 (34)
3.6电路测试与分析 (34)
3.7本章小结 (37)
第4章 提高电流稳定度的关键电路 (38)
4.1稳流源调整管压降控制方法概述 (38)
4.1.1变压器分档法 (38)
4.1.2电机控制调压器法 (38)
4.1.3开关电源组合法 (39)
4.2稳流源调整管压降反馈补偿电路的设计 (39)助学金申请理由100字
4.2.1设计原理 (40)
4.2.2电路组成 (41)
4.3辅助电源的设计 (46)
4.4电路测试与分析 (47)
4.5本章小结 (48)
第5章 试验样机与主要性能测试 (49)
印度人口多少亿
5.1试验样机 (49)
5.2主要性能测试 (50)
5.2.1电流稳定度 (50)
5.2.2输出阻抗 (52)
5.3本章小结 (53)
