Power System Design Of Laser Diode Based On DSP

Semiconductor lasers exhibit a lot of very important features which are different from other kinds of lasers such as compactness ,light weight , high wall-plug efficiency ,long operational lifetime ,ability to be directly modulated with the electrical signal of high frequency up to 10 GHz. They can be integrated with similarly construction devices such as modulator or switches .Thus ,semiconductor lasers have been playing more and more important role in the fields of the national economy.The electrical drive sources of semiconductor lasers have very important effect on their operational lifetime and reliability. The developing direction of current laser power supply is being digital, being intelligentized and being modularized. The paper gives out the groping research about the second-design with the microprocessor TMS320LF2407 which TI company lately promulgates as the control core, and the electrical drive sources as the research object .Taking advantage of the DSP chip's high calculating ability and the abundant external facilities that are especially used for control yield, we can integrate the microprocessor function for digital control, the periphery circuits into a piece of chip. Compared with current power supply control system, the hardware quantity is consumedly reduced, and the integration degree is increased in this system . First, according to the new hardware request of this chip, the optimum realizing project of the control circuit, low-pressure power supply circuit and external referenced control circuit is gave out,other hardware parts primarily include the sampling and processing of output current and driving of digitally-controlled potentiometer . The paper brings up the PID algorithm aimed at the control system. With the system as the simulation object, using MATLAB model, adopting the PID algorithm to proceed the current closed loop control, I verified and analyzed the PID parameters. The simulation result shows that the output current wave of this project has good performance such as fast transient response, little overshoot which meets to the requirement, improves system real-time quality and improves the whole performance of the power supply. Finally, the related software of digital control of the system is designed. In details, it includes the system initialization, the realization of soft start and A/D transformation, the current sampling filter, the drive of digitally-controlled potentiometer and PID modulator etc.. And then the software's possibility is verified by experiment. The control system is total digital control with the control project realized all in software, so that we can promote system to higher grade and perfect its function in condition of completely not changing the hardware. At the same time, digital control can bring the advantages of strong anti-disturbance, high dependability, debug convenience. The experiment result proved that the control system have excellent input-output characteristic, can achieve the digital control of module power supply.