Design And Research Of A Laser Temperature Control System Based On DSP

With the development of semiconductor technology,semiconductor laser emerges as the times require.Semiconductor laser has been widely used in modern industry,medicine,national defense fields etc because of the advantages of the small size,low cost,low energy consumption,high efficiency,long life and high absorption.However,the performance of semiconductor laser is easily affected by temperature variation.If the operating temperature cannot be strictly controlled,the output power,the wavelength and the service life of semiconductor lasers will be affected.Therefore,developing a temperature control system of semiconductor laser has a certain practical significance.This thesis was aimed at designing a semiconductor laser temperature control system based on DSP.According to the design flow,it can be divided into five parts,including the design of scheme,control algorithm,hardware circuit and software,and system debugging.The system adopted closed-loop control with higher control precision,the temperature sensor adopted platinum thermistor Pt100 with four-wire fabrication,using the build-in 12 bits ADC converter in DSP as the A / D converter,the temperature control was carried out by ceramic heating chip which was drived by power switch.Through the research and analysis of PID control and fuzzy control,the fuzzy PID control algorithm was designed according to the control requirements of the system,and the mathematical model of the system was established according to the principle of heat balance.The feasibility of the algorithm was verified by system simulation in Simulink.In this thesis,the TMS320F2808-DSP of TI was used as the core controller to design the hardware circuit of the system,includeing the peripheral circuit of DSP,temperature acquisition circuit,power switch circuit and CAN-bus communication circuit.With the software was accomplished with the platform of LabVIEW and CCS.The temperature data acquisition and display was realized by LabVIEW in upper computer,and the lower machine realized such functions as data acquisition,fuzzy PID control algorithm,CAN communication and outputting PWM control signal by CCS.A testing platform was built to verify the reliability of the system.The results show that the system can reach the target temperature within 300 seconds,and the stable fluctuation range of the system is less than 0.2?,which fully meets the requirements of the design.