Research On The High-power Pumped Semiconductor Laser Pulse Driving Power Supply

DPSSL system has small volume,high efficiency,good reliability,long working life,so it has been widely used in the national defense,scientific research,medical treatment,processing,and other fields.DPSSL system use laser diodes as a pumped light source,and solid-state laser absorbs the laser emitted by laser diodes,emitting laser.The stability and the ripple current of the driving current of laser diodes can change the optical power,the center wavelength and the wavelength spectral line width of the laser.Solid-state laser requires ideal pumped laser with narrower linewidth,stable center wavelength and suitable photon intensity.If laser diodes send so ideal laser,the drive current must be high stability and small ripple current.Therefore,high-power pumped semiconductor laser driving power supply is a very critical technology in DPSSL system.This subject has carried out the research work on high power pumped semiconductor laser driving power supply.In this thesis,the working principle and characteristics of semiconductor lasers are firstly analyzed,and the requirements of high power pumped semiconductor lasers for pulse driving power supply are summarized.And then the thesis carefully analyzes this field of researches,determining to adopt the pulse-driven power supply system composed of the former charge unit and the post-stage pulse discharge unit.The pre-stage charging unit adopts the LCC resonant converter,and the post-stage pulse discharging unit adopts the circuit based on the large capacitance energy storage with linear controling the MOSFET.The system operates as follows: First,the pre-stage charging unit charges the storage capacitor voltage from zero to the set voltage,and the pre-stage charging unit stops working.The set voltage is greater than the threshold voltage of the semiconductor laser load;Secondly,the post-stage pulse discharging unit starts to work,sending a pulse driving current,and the storage capacitor voltage is still greater than the threshold voltage of the semiconductor laser.Finally,during the pulse discharging gap,the pre-charge charging unit continues to work,and when the storage capacitor is charged to the set voltage,the former charging unit to stop working.The pre-charge charging unit complements the lost energy of the storage capacitor duing to the discharging pulse.In this subject,the pre-charge unit should be able to charge a large capacitance with load constant current and adapting to a wide range of load change.By analyzing the double pulse mode of LCC resonant converter,the converter can not only meet the requirements of the pre-charging unit,but also realize the soft switch improving the efficiency of the system.According to the converter operating mode,the design method of resonant parameters is deduced.In this application,the post-stage pulse discharging unit needs the pulse discharging circuit to meet two points.First,the output current should meet the large amplitude and high stability.During rising process the current is not overshoot and the rise time of current is short.The falling time of current is short and not reverse current.Second,the output voltage should be greater than the threshold voltage of the laser diode array.By analyzing the advantages and disadvantages of the current pulse discharge method,a linear current control method based on capacitance energy storage is adopted.The working principle of the pulse discharge circuit composed of the linear control MOSFET is analyzed,and the transfer function of the main circuit is obtained.By analyzing the characteristics of the system,correction links to improve the performance of the system is used,so that it can meet the post-discharge circuit for the output current requirements.When the MOSFET is used for linear regulation,the drain-source voltage is the difference between the voltage of the storage capacitor and the laser diode array,so the loss of the MOSFET is very large and the device is easy to be damaged.This thesis discusses the protection scheme based on MOSFET forward offset safe working area(FBSOA).When the driving current exceeds the rated current of the semiconductor laser,the laser is easily damaged,and the overcurrent protection scheme is designed in this thesis.By simulation and experiment,the feasibility of the high power pumped semiconductor laser driving power system is verified.Pulse drive power system experimental single MOSFET output indicators are as follows: maximum output 140V/ 70 A,adjustable pulse width 200us-300?s,the current rising time 19?s and the repetition rate of 100 Hz.The pre-charge charging unit LCC resonant converter's maximum output power is 2600 W and the maximum output voltage is 350 V.