Design Of LD Switching Power Supply With Power Adaption

With its small size, low price and high efficiency, good reliability, long working life and excellent color adjustable feature ,Laser diode (LD) is more widely used in national defense, scientific research, medical, processing and other fields. With the wide spread application of semiconductor laser, its drive power requirements are increasing. The traditional power semiconductor lasers are generally driven by linear power supply, while this kind of bulky power has conversion efficiency and low power consumption. Therefore, the use of switching power supply which has been developed as the drive power of emiconductor laser e shows its more advantage. Traditional LD asks the drive power to provide the corresponding constant current drive according to its own different requirements of to realize his stable power output.If you want to provide different specifications of the LD power-driven, we need to change the output of the adjustment drive power power.Then, the accuracy is not only difficult to control, but also let the work itself becomes complicated.A design of laser Diode (LD) driver based on switching power supply with power adaption is introduced, which uses the single chip microcomputer as control center, combined with external hardware system and PID algorithm, can realize the constant current drive and power adaptive adjustment of the LD by changing the insulated gate bipolar transistor (IGBT) duty cycle of switching power supply. As the experiment results show, this drive circuit has a low ripple factor, high efficiency, and the stability of optical power output is better than 0.5%, which can meet the practical needs of LD.This design uses a microcontroller to receive data through the A/D conversion, and compared with the parameters set, then the results are sent to the D/A converters, control the interface circuit like LCD display and keyboard, and the controllability of the system has been realized. The module design method is used in the hardware Circuit design, and there are constant current source circuit, V/I conversion circuit, power sampling circuit, and the D/A converter circuit. And in connection with the delicate nature of the semiconductor laser, we also designed specifically to add the protection of electrical, temperature control unit and a soft-start circuitry to ensure the semiconductor laser work stablely, accurately, reliablely and safely.The main contents of this paper are as follows:(1) Describes the advantages of semiconductor lasers, development history, applications, and the research status of semiconductor laser drive power home and abroad, and we have a general understanding. This thesis discusses the content and significance. Carry out a depth study of the working principle of semiconductor lasers, the system describes the failure mechanism of the semiconductor laser and obtaines notes when using the semiconductor laser.(2) Introduces the application and development of switching power supply, describes the working principle of switching power supply in detail, and introduces several typical main switching power supply circuit and then compares their advantages and disadvantages.(3) According to the requirements of the semiconductor lasers power, designes a new switching power supply with power-based adaptive function of laser diode (LD) drive power, the design uses a switching power supply as a laser driver, and power adaptive can be realized.(4)Designes hardware module circuit in the system, including the power sampling circuit, V/I conversion circuit, D/A circuits and the slow-start circuit, then analyzes them. Designes temperature control unit and the protection circuit, then describes the anti-jamming measures of the system in detai.(5) Studyes the control core microcontroller and its features in detail, and designes and analysises the connection circuit of D/A, display, keyboard, including a simple introduction to the use of the device.(6) Details of each function module hardware circuit are analyzed, and obtaines corresponding theoretical derivation. Describes the design of adaptive control procedures, according to the software design requirements and implementations of each function subroutine provides a precise PID control algorithm.(7) According to the circuit schematic and experimental analysis of test results, draw conclusions.