Research And Development Of Inverted Power Supply For Plasma Cutting Machine

With the development of Chinese industry,the domestic demand for metal cutting quality is getting higher and higher,and the demand for cutting machine is also increasing.At present,as the core component of plasma cutting machine,power supply’s market is basically monopolized by imported products,and the competitive power of domestic power supply is poor.In order to break the monopoly of imported products and improve the competitive advantage of domestic plasma cutting power supply,this paper deeply studys the technology of plasma cutting machine and developed a prototype of the digital inverted power supply for plasma cutting machine.The main research contents and innovations are as follows:1.In the base of the design and commissioning of the BUCK type plasma cutting power supply with 260 A output current,the solution that using high frequency inverted power supply as the small plasma cutting power supply with 105 A output current is determined;2.The theory of gas discharge of plasma arc is analyzed,and the special requirement of plasma arc to power supply is mastered.The circuit structure of inverted power supply is established,and the small signal analysis and computer aided analysis based on MATLAB/SIMULINK are carried out to verify the feasibility of power circuit and control strategy;3.The circuits is designed,including plasma cutting inverted power circuit,control circuit and so on.The main power nodes and the electrical parameters of the loop is calculated.The key components,such as the power module and high frequency inverted isolation transformer is determined.The schematic and PCB diagram is drawed,and the PCB board is completed;4.Inverted power supply’s control programme is developed.The overall structure of the program and the main function modules are designed,including a variety of sampling circuits,PWM generation,PID regulation,fault processing,communication procedures and so on.The plasma cutting machine’s work sequence is programmed,to ensure the normal operation of plasma cutting machine;5.In order to meet the test requirements of batch production,the test platform of the control circuit board is designed.The design scheme of hardware and software is given,and the prototype of the testing platform is finished;6.The prototype of plasma cutting machine’s inverted power supply is completed.Through the debugging of hardware and software,the basic function is realized,and the performance index is achieved.The test results show that: the PWM driver is stable,the output current ripple of the power supply meets the design requirements,the gas pressure control is fast and reliable,the power supply’s working time sequence design is reasonable,and the complete cutting process of the plasma cutting machine can be achieved.Finally,by using the prototype,8mm low carbon steel cutting test is taken.The results show that the cutting effect is good,and has basically reached the level of similar foreign products.The above tests and experiments show that: the overall scheme of the inverted power supply for plasma cutting machine is correct and feasible,the structure and parameters’ design is reasonable,the software and hardware is stable and reliable,and the overall performance of the prototype has reached the level of similar foreign products.