基于模糊PID控制的控温箱设计

Design of incubator based on fuzzy PID control

为满足标准电阻量值传递时苛刻的温度要求,设计了精度高、稳定性强的控温箱。通过四线制温度传感器Pt100实现控温箱内腔温度的采集,模糊比例—积分—微分(PID)控制器通过改变脉宽调制输出的占空比控制发热电阻的功率,以保持温度稳定。通过改变内腔中外加功率电阻的发热量,模拟标准电阻发热,以测试控温箱内部抗干扰能力;通过多点比对法对控温箱内腔温度的均匀性进行评价。经过数据分析,控温箱稳定性优于1 m K,温度不均匀性低于6 m K,当外加功率小于0.31 W时,控温箱能保持稳定。结果表明,控温箱抗干扰性能良好,稳定性及均匀性满足要求,可以为标准电阻量值传递提供稳定的温度环境。

In order to meet the temperature requirement of standard resistance when the quantity value is transferred,an incubator with high precision and stability is designed.The acquisition of the temperature in the chamber is realized by the four-wire platinum thermal resistor Pt100.The fuzzy proportional-integraldifferential(PID)controller controls power of heating resistor by changing the duty ratio of the PWM output to keep the temperature stable.The standard resistor heating is simulated by changing the power resistor heating in the inner cavity to test the anti-interference ability of the incubator.The uniformity of temperature is evaluated by multi-point comparison.After data analysis,the stability of the incubator is better than 1 mK,and the temperature non-uniformity is lower than 6 mK.When the applied power is less than 0.31 W,the incubator can maintain stable.The experimental results show that the incubator has good anti-interference performance,and its stability and uniformity meet the requirements.It can provide a stable temperature environment for value transfer of standard resistance.