石墨炉加热控制系统设计

Design of Graphite Furnace Heating Control System

目前,对各类污水中的金属元素含量进行检测的方法以原子吸收光谱法较为常用。不同于温度不易控制的火焰法和适用范围较小的氢化物法,采用石墨炉法具有检测范围大和原子化效率高等优点。石墨炉的工作温度稳定性直接影响测量元素含量的精度,而石墨炉的温度取决于施加在两端的电压控制。为实现对石墨炉工作温度的精准、快速控制,设计了一种石墨炉温度控制系统。利用控制双向可控硅的导通和闭合角度的方法,改变石墨炉的当前工作电压值;同时,通过可选择的光反馈回路和电反馈回路对石墨炉的工作电压进行精确控制,并通过Simulink对控制系统进行整体仿真和实际电路的测试。试验结果表明,使用该控制电路系统对电压进行控制,具有高速率的调节效果且控制效果稳定。

At present,atomic absorption spectrometry is the more commonly used method for the detection of metal element content in all kinds of sewage.Different from flame method with difficult temperature control and hydride method with a small detection range,the graphite furnace method has the advantages of a large detection range and high atomization efficiency.The working temperature stability of graphite furnace directly affects the accuracy of element content measurement,and the temperature of graphite furnace depends on the voltage control applied at both ends.In order to realize the accurate and rapid control of the working temperature of graphite furnace,a graphite furnace temperature control system is designed.The current working voltage value of the graphite furnace is changed by controlling the on-off and closing Angle of the bidirectional SCR.Meanwhile,the working voltage of the graphite furnace is precisely controlled by the optional optical feedback loop and electrical feedback loop,and the control system is simulated and tested by Simulink.The experimental results show that this control circuit system can control the voltage at a high rate and the control effect is stable.