(1.Department of Modern Physics， University of Science and Technology of China， Hefei 230026， China； 2.State Key Laboratory of Particle Detection & Electronics， University of Science and Technology of China， Hefei 230026， China)
Abstract： Thermostat plays an important role in people′s production, life and scientific research, such as the measurement and compensation of temperature compensated crystal oscillator parameters. This paper designs and implements a software-controlled portable thermostat control system with low fluctuation. This thermostat uses a method to control the power of ceramic heating chip or semiconductor refrigeration chip by dynamically adjusting the working voltage, so as to realize the constant control of temperature. This thermostat has advantages of low temperature fluctuation, supporting temperature curve software control, small and portable. After testing, the temperature control range of the thermostat realized in this design is from -15 ℃ to 80 ℃, and the temperature fluctuation in stable state is ±0.2 ℃. In addition, compared with the thermostat using pulse width modulation control method, this thermostat has lower system electromagnetic radiation and higher refrigeration efficiency. Under the same power input condition, the temperature can be further reduced by 12.9 ℃.
Key words : thermostat；temperature control；high efficiency；low fluctuation
溫度控制系統(tǒng)需要控制加熱或制冷設(shè)備的輸出量，使之與系統(tǒng)的散熱量或散冷量相當(dāng)，進(jìn)入熱平衡狀態(tài)，從而達(dá)到控溫的目的，其中的難點在于對溫度波動度的控制。在溫控系統(tǒng)的設(shè)計中，可以采用PWM（Pulse Width Modulation）模式來調(diào)節(jié)加熱或制冷設(shè)備的工作時長，從而控制這些設(shè)備的平均功率，也可以使用DAC（Digital to Analog Converter）模塊并采用動態(tài)調(diào)整電壓的方式來控制這些設(shè)備的輸出功率。文獻(xiàn)中的溫度控制系統(tǒng)大多采用PWM模式來驅(qū)動加熱或制冷設(shè)備，例如，文獻(xiàn)[4]中吳蒙娜設(shè)計了一種粒子加速器溫度控制系統(tǒng)，通過單片機(jī)輸出不同占空比的PWM波，并采用H橋驅(qū)動電路來雙向驅(qū)動制冷片，從而實現(xiàn)了±0.2 ℃的控溫精度；文獻(xiàn)[5]中McDowell等人設(shè)計了一種用于植物生長試驗的溫度控制器，通過Arduino Nano開發(fā)板輸出PWM模式，在大電流范圍內(nèi)對加熱器和空調(diào)進(jìn)行控制，實現(xiàn)了±0.3 ℃的控溫精度。
