高精度温度控制的真菌培养箱的研制

The Development of High Precision Constant Temperature Incubator for Fungi

目的:由于某些真菌的特异性,对生长环境温度有较高要求,而现有的培养箱不能满足临床要求,需要研制高精度温度控制的真菌培养箱。方法:高精度温度控制的真菌培养箱温度控制系统采用精密恒流源激励电路、Pt100传感器、V-F转换器和单片机实现高精度的A/D转换。采用AD650进行V/F变换,AD650的输出频率信号,经过D触发器7474进行二分频、边沿整定和占空比调整,为保证AD转换与控制器电气隔离以减小干扰,我们使用了东芝6n137高速光电耦合器进行隔离。转换出来的频率信号由SOC级MCUC8051F020的T0口进行采集测量,结果送控制器,经PID控制运算输出16位PWM信号,通过控制固态继电器SSR的通断来实现真菌培养箱内部的恒温控制。运用PID控制原理,通过精心选择PID的各种参数,实现了高精度的恒温控制。结果:经过试验和测量,高精度温度控制系统保证了真菌培养箱内部温度的波动不大于±0.2℃,满足了真菌生长的温度环境要求。结论:基于精密恒流源激励电路、Pt100传感器、V-F转换器和PID温控器技术研制的高精度温度控制真菌培养箱能够完成高精度温度控制,保证了特异性真菌正常生长的温度条件。

Objective： Some special kind of fungi need precision constant temperature environment. High precision constant temperature incubator is not available now.For this reason,a kind of high precision constant temperature incubator for fungi need to be developed. Method： This high precision constant temperature incubator system, which is built in the base of Pt100 sensor circuit, Pt100 excitation current source circuit, V/F converter circuit ,MCU and SSR, can deliver A/D result with high precision. To achieve high precision, The inputting Pt100 voltage is first amplified and deflected,and then delivered to AD650 to perform V/F.A kind of D type trigger 7474 is used for modify frequency signal. High speed transistor optocoupler 6N137 can achieve wide bandwidth frequency signal coupling.The outputting frequency is measured with high precision by TO port of MCU C8051F020, and the Micro-controller calculate the result and give PID output signal by 16 bit PWM to heater.Result： It is an effective method to achieve high precision constant temperature control between ±0.2℃.Conclusion： Based on current source circuit and Pt100 sensor and V-F converter and PID technology, the high precision constant temperature incubator for fungi can be developed.