基于镜像脉冲的电磁力平衡传感器控温方法  

Temperature control method for electromagnetic force balance sensor based on image pulse

作　　者：黄强[1] 滕召胜[1] 唐享 林海军[3] 刘亚坤[1] 

机构地区：[1]湖南大学电气与信息工程学院,长沙410082 [2]湘电集团有限公司,湘潭411101 [3]湖南师范大学工学院,长沙410081

出　　处：《仪器仪表学报》2015年第11期2479-2486,共8页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金(51205127)项目资助

摘　　要：电磁力平衡传感器因温度变化引起的示值漂移误差达-40.3 mg∕℃,远不能满足分辨力为0.1 mg及以上的电子分析天平计量性能要求。详细分析了温度对脉冲电流工作模式下电磁力平衡传感器输出误差的影响,根据传感器结构特征及散热方式,设计了一个PT1000高精度温度检测模块,利用等幅正、负脉冲且脉宽可调时动圈发热改变但平衡状态不变的特点,提出一种基于脉宽调制器(PWM)镜像脉冲的电磁力平衡传感器温度控制方法。该方法消除了因不同质量物体加载动圈发热不恒定引起的传感器输出误差,根据外界环境温度引起的传感器温度变化量,同步进地调节镜像脉冲的2个死区时间,实时改变动圈发热功率,维持传感器温度稳定。实验研究表明,采用上述研究方法后,电磁力平衡传感器漂移减小至3.1×10^(-6)g∕℃,有效降低了天平温度漂移补偿算法的难度。The indication error of electromagnetic force balance sensor（ electromagnetic force compensated load cell） caused by temperature variation could reaches- 40. 3 mg ∕℃,which is far difficult to meet the requirements for the measuring performance of the electronic analytical balance with the resolution of 0. 1 mg or better. In this paper,the impact of temperature on the output error of electromagnetic force compensated load cell under pulse current operation mode is analyzed in detail. According to the structure of the load cell and the heat dissipation mode,a high-precision temperature detection module is designed by adopting PT1000. Based on the characteristic that the heating power of the coil is changed at the same equilibrium state by changing the width of the positive and negative pulses with equal amplitude,a temperature control method for the electromagnetic force compensated load cell is proposed on the basis of the pulse width modulator（ PWM） image pulses. This method eliminates the output error of the load cell caused by the inconstant heating power of the coil when the objects with different masses are loaded. According to the temperature variation in load cell caused by ambient temperature,the two dead-time widths of the image pulse are adjusted with the same step,which changes the heating power of the coil in real time and maintains the temperature of the load cell stable. The experiment results show that adopting the proposed method,the temperature drift of the electromagnetic force compensated load cell is reduced to 3. 1 × 10^-6g∕℃,and the difficulty of the temperature drift compensation algorithm for the balance is effectively cut down.

关 键 词：电磁力平衡传感器 温度漂移 脉宽调制器 镜像脉冲 温度控制 

分 类 号：TH715.116[机械工程—测试计量技术及仪器]