The Research Of IGBT Inverter Plasma Cutting Power Supply

Plasma cutting method is a high energy melting cutting method, which is based on plasma arc. It has advantages comparing with other cutting methods, such as high cutting speed , narrow heat effect zone, little deformation of workpiece , wide suitability , simple operation and so on. So far, plasma cutting has become an indispensable new technics in machine making technology.Inverter cutting technology is an important applying subject that requires arccutting load characteristics and cutting technics.It uses modern power electronics and automatic control theory to realize power transform and control. The research includes welding arc physical, cutting technology, power electronics and electromagnetic equipment, switching circuit topology, etc. Cutting inverter is designed to high efficiency, less power consumption and excellent quality.The component parts and control principle of plasma cutting inverter power source are introduced in the paper. Main circuit, safeguard circuit, driver circuit and high frequency arc starter are respectively analyzed. Hardware and software are both expatiated systematically.The main circuit is made up of rectifier, filter, high-frenquency transformer, output reactor, and full-bridge inverter, in which 4 IGBT modules are adopted. The key points in designing high-frequency transformer, as well as the characteristics of IGBT are discussed. The main circuit is simulated by simulink of MATLAB.At the same time, in order to obtain accurate and real-time control, high performance 16-bit microprocessor 80C196KC is adopted for control kernel. The digital signal from microprocessor are firstly converted into analogy signal, which is then modulated by pulse width modulate (PWM) chip SG3525 into two pulses without overlapping each other. At last the pulses are used to triggering IGBT after they are magnified. In addition, the resource distribution of microprocessor and the functions of peripheral circuit are given.The safeguard circiut mainly consists of over-current, over-heat, over-votage and low-vogate circuits.Reliability and noise resistance designs are also introduced. Various noises probably appearing in the whole system, as well as their causation, are analyzed systematically. Then, in order to reduce their bad infections, some hardware and software measures are adopted while designing schematic chart, PCB board, and compiling code.In addition, some problems in designing of inverter power source are also probed. The control system are debugged, and the implement measures, component parts and some problems arising in debugging process for the inverter power source were analyzed through the experimentation. At last, some advices on future research for the plasma cutting inverter power are given, and they will lay the foundation for the future research of plasma cutting power.