一种新的无漂移磁通测量方法  

A New Method for Measuring Magnetic Flux with No Drift

作　　者：徐顺利[1] 

机构地区：[1]南京大学,南京210093

出　　处：《南京大学学报（自然科学版）》2001年第5期649-652,共4页Journal of Nanjing University（Natural Science）

摘　　要：实现磁通测量 ,通常采用运算放大器和阻容网络构成模拟积分方法 ,完成对输入感应电压的时间积分 ,然而却存在着系统漂移问题 .采用乘法与求和实现数字积分运算 .系统硬件主要由高性能运算放大器、A/D转换器、单片机、等部件组成 ,编写必要的控制、滤波及运算软件支持 ,实现了放大、模数变换、定时、运算、显示等功能 .由于不需要用电容来实现对输入量的积分 ,所以系统不存在传统电容积分所固有的漂移问题 .根据此原理设计了电路并进行反复测试 ,系统稳定性。The traditional measurement of magnetic flux uses analog integration and thus zero point drift and measurement drift always exist in the output.To overcome this drawback we report a novel design for magnetic flux measurement with high stability. Our design is based on a new approach to realize the function of integration by a combination of multiplication and summation to solve the problem of zero drift in the traditional method. From the definition of integration,it can be realized by:Φ=-∑e i△t when time interval △t is sufficiently small. Accordingly,in our design,e i is measured first and then by analog-digit convertion it is transformed into a digital quantity and multiplied with △t The result is finally summed up to accomplish the whole operation of integration. The time interval can be set according to the requirement of precision. Generally,the measurement of magnetic flux is accomplished in a period of time of the order of second. Therefore setting △t at the order of microsecond is quite enough for the precision. In our design,the hardware includes primarily high performance operation amplifier, A/D converter, single chip microprocessor etc. The necessary software for controlling, filtering and operation is made for supporting the hardware. Since capacitance is not used for integration of the input quantity, the drift, inherent to the traditional integrator,does not appear in this new system. Repeated tests of more than 10 groups were made for 10 times per group with △t=100 ms. The standard deviation,σ,of each group falls between 0.007～0.016. The reliability is high. In addition, a standard electromotive force of (50.00±0.01)mV is set in the system. After integrating this electromotive force for 1 second by the above method the result of (50.00±0.01)m Web is obtained. Thus,a quantitative measurement on samples is realized with internal calibration in this system.

关 键 词：磁通测量 模拟积分 数字积分 运算放大器 A/D转换器 单片机 电路设计 

分 类 号：TM936.2[电气工程—电力电子与电力传动] O441.5[理学—电磁学]