A millikelvin precision temperature control system designed for a low cost, portable and variable temperature blackbody from 298.15 to 693.15 K.

The article focuses on the design and verification of a low-cost, portable, and millikelvin precision temperature measurement and control system for a variable temperature blackbody radiation source operating from 298.15 to 693.15 K. Utilizing a four-wire Pt100 platinum resistance thermometer combined with a round-robin measurement structure and current reversing technology, the system achieves temperature measurement precision better than 0.5 mK. To improve dynamic performance and avoid overshoot common in traditional PID controllers, a feedforward and segmented PID (FS-PID) controller based on a heat transfer model and self-tuning algorithm is implemented, resulting in temperature stability better than 3 mK over 10 minutes. The system offers comparable temperature stability to high-performance metrological blackbodies but at a lower cost and with portability suitable for on-site calibration, addressing limitations of existing commercial blackbody sources in both metrology and industry.