Research On Adjustable Pulse Power Supply

As the fundament of variable electrical equipments, power supplies realize power changing and delivery. Pulse power supply, with its discrete characteristic, has a wide application in the field of EDM, pulse electroplating, electric weld, high power laser pump, high frequency induction heating, purification of exhaust gas and waster water, electrostatic dust precipitation, ozone production and surface heat treatment. In different fields, demands of performance and parameters of pulse power supply are variable, so as the techniques of manipulation. After the research on characteristics and principles of many pulse powers, a novel, intelligent, high frequency pulse power supply with adjustable amplitude, frequency and duty is developed which has a favorable foreground in engineering application and a great theoretical significance.With chopping principle, switching power supply is chosen as the DC power supply because of its small size, low weight and high efficiency. With the application of current mode control chip UC3842 as the core of the circuit, and with the cooperation of high frequency transformer, MOSFET, output inductor, sampling and feedback circuit, a forward converter is projected whose maximal output current is 5A and output voltage can be regulated between 5V to 30V continuously. Moreover, based on small signal analysis method, the equivalent small-signal model of the main circuit is achieved, and the system transfer function is established by predigesting the double control loop to a single one. On the basis of transfer function, the frequency characteristic of the system is analyzed and the compensator is designed. Emulation results show a good dynamic characteristic of the closed system.In order to control the forementioned switching power supply to accomplish an adjustable pulse voltage, the microcontroller W77E58 is combined with some programs to form an intelligent control system whose primary function is regulating and driving pulse signal. And the main modules of the system contain analog input module, user dialog module, frequency dividing module and isolate-driving module.At the end of this paper, pertinent experiments which mostly focus on function and protection test have been carried out on the pulse power supply. Based on the results, the very pulse power supply meets corresponding function requirements on output voltage regulation, load regulation, output ripple and dynamic response, and the power also has a tolerable waveform speciality and an excellent ability of over current protection and short protection.