高精度磁悬浮式电子秤的若干技术问题

Some technical problems of the high precision magetic suspension electronic balance

论述了高精度磁悬浮式电子秤中的几个关键技术问题，即非线性问题、提高时间间隔的测量精度问题以及温度补偿等．由于存在这些问题，所以中高精度电子秤不能用连续控制机构成闭环的方法实现．用ＰＷＭ（脉冲宽度调制）形式的电流信号产生磁悬浮力，以避开电流与磁悬浮力之间的非线性，并转化为时间间隔τ与悬浮力ｆ间严格的线性关系．在此基础上，提出对τ作量化和平均处理的方法，以提高对τ的测量精度．最后论述温度补偿的重要性。

This paper deals with several critical technical problems of the high precision magnetic suspension electronic balance, that is, nonlinear problems, the improvement of the measuring accuracy of the time interval, and temperature offset. The existence of these problems prevents the realization of a high precision electronic balance by traditional continuous control closed loop system. The paper is centered on analyzing how to produce the magnetic suspension force with PWM current signals, which could avoid the nonlinear problems between current and magnetic suspension force, and lead to strict linear relations between time interval τ and magnetic suspension force f . On this basis, the methods of quantizing and averaging τ are provided in the paper in order to improve the accuracy of the measurement of τ . Finally, the importance of temperature offset is discussed, and several efficient methods how to realize temperature offset are presented.