(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
温度控制系统需要控制加热或制冷设备的输出量，使之与系统的散热量或散冷量相当，进入热平衡状态，从而达到控温的目的，其中的难点在于对温度波动度的控制。在温控系统的设计中，可以采用PWM（Pulse Width Modulation）模式来调节加热或制冷设备的工作时长，从而控制这些设备的平均功率，也可以使用DAC（Digital to Analog Converter）模块并采用动态调整电压的方式来控制这些设备的输出功率。文献中的温度控制系统大多采用PWM模式来驱动加热或制冷设备，例如，文献[4]中吴蒙娜设计了一种粒子加速器温度控制系统，通过单片机输出不同占空比的PWM波，并采用H桥驱动电路来双向驱动制冷片，从而实现了±0.2 ℃的控温精度；文献[5]中McDowell等人设计了一种用于植物生长试验的温度控制器，通过Arduino Nano开发板输出PWM模式，在大电流范围内对加热器和空调进行控制，实现了±0.3 ℃的控温精度。
