一种大功率TEC温控系统的设计

Design of a TEC temperature control system with high power

摘要:

小功率半导体激光器常采用TEC片进行温度控制，其中，TEC片工作电压为5V，工作电流低于4A的应用已经有了几种成熟的芯片方案，而更高电压和电流的TEC温控需要自行设计控制系统。设计了一种基于AVR单片机ATmega128，适用于较大功率TEC片的温控系统，主要技术指标包括：TEC片工作电压范围6V-24V，峰值电流≤20A，控温范围：0-70℃，控温精度±0.05℃。使用负温度系数热敏电阻采集温度，包含温度信息的电压值转化为数字量输入单片机，单片机根据位置式PID控制算法的计算结果输出控制信号，驱动由两片BTN7971B构成的H桥电路，H桥输出电压提供给TEC片。对硬件和软件的实现方法进行了详细分析，重视控温精度、系统的可靠性设计。经过实际测试，可实现前述技术指标，能满足较大功率半导体激光器的控温要求。

Abstract:

Low power semiconductor lasers often use TEC chips for temperature control, among which, there are several kinds of mature applications for temperature controller of working voltage of 5V and working current less than 4A. For bigger voltage and current, a unique control system needs to be designed. A temperature control system based on AVR single chip microcomputer ATmega128 is designed, which is suitable for high power TEC chip. The main technical specifications include: the working voltage range of TEC chip is 6-24V, the peak current is up to 20A, the temperature control range is 0-70 ℃, and the temperature control accuracy is ± 0.05 ℃. A negative temperature coefficient thermistor is used to collect the temperature, and the voltage containing the temperature information is converted into a digital value and then sent to the single chip microcomputer. According to the calculation result of position type PID control algorithm, the microcomputer outputs the control signals, which drive the H-bridge circuit composed of two BTN7971B, and the H-bridge output voltage is provided to the TEC chip. The realization methods of hardware and software are analyzed in detail, and the temperature control accuracy and system reliability are emphasized in design. After practical tests, the technical specifications can be achieved, and the temperature control requirements of higher power semiconductor laser are met.