Integrated Design Of Constant Current Driving Power Supply For High Power Fiber Laser

Fiber laser has the advantages of good beam quality,excellent heat dissipation performance,and high conversion efficiency,and are widely used in optical communication,spectroscopy,optical sensing and military and national defense fields.The current stability and system reliability of the laser power supply have a great influence on the output power and service life of the fiber laser,especially for highpower fiber lasers,which have higher requirements for laser power supply.In view of the shortcomings of the domestic fiber laser drive power supply,such as low integration,poor control ability,low drive current and high current stability,poor power dissipation capability,etc.This article has carried out the design of high-power fiber laser constant current drive power supply with low current stability,high reliability,excellent heat dissipation performance,small size and relatively complete functions.The high-power fiber laser constant current drive power developed in this thesis uses a closed-loop feedback control to make the MOS tube work in the amplifying area to output a constant current.The output current of the constant current driver board corresponding to the pump source reaches 20A;in order to monitor the laser output power and for the surface temperature of some optical modules,the power and temperature detection circuits are designed;in order to obtain better temperature control for constant current drive,a triple heat dissipation structure is adopted;the temperature changes of the casing and nozzle of the pump source are analyzed,at the same time,in order to measure the stability of the driving current,a test of the instability of the output power of the pump source is carried out;and assemble the optical module and the laser power supply and test the output power of the fiber laser;finally,the technical indicators of this laser power supply and similar power supplies at home and abroad are compared.The main research contents of this thesis are as follows:1.Analyze the requirements of the system,completed the introduction of the principle of ytterbium-doped double-clad high-power fiber laser and selected the pump source and seed source,and determined the conventional requirements and power supply types of the laser power supply,and give the main technology indicators,functions and overall design plan of laser power supplies.2.The constant current control of the laser power supply adopts a closed-loop feedback control method,the hardware circuit designed includes the main control board circuit,D/A and A/D conversion circuit,signal distribution circuit,constant current drive circuit,signal acquisition circuit,protection circuit,etc.,and introduces the design principle of the circuit,the selection of some chips and components.3.Software design adopts modular thinking,including a main program and multiple subprograms,and design the host communication protocol to realize the precise control of the power supply and the real-time acquisition of the signal;the parameters of the laser can be observed in real time through the host computer software,and alarm thresholds and power fitting coefficients can be set according to requirements.4.Finally,the laser power supply is tested and analyzed.The rise time when the circuit is opened and closed is about 4.5ms,the fall time is about 6.5ms,and the stability of the operating current is at or better than 10-3.When the working current is 20A,the ripple coefficient is 0.36%,the instability of the output optical power of the pump source is less than ±0.5%.The output power of the whole fiber laser is greater than 2.8kW,and the stability is better than 5%,the constant current drive board has a good heat dissipation effect,the test results all meet or exceed the design technical index requirements.