Study On The Digital Control System Of VPPA Welding Power

In the modern processing and manufacturing industry,the application range of welding technology is becoming more and more extensive.Among them,in order to improve the quality and production efficiency of aluminum alloy welding products,the variable polarity plasma welding power source is particularly important.The high-performance digital control system is the most critical part of the variable polarity plasma welding power source.Regarding the variable polarity plasma welding power source digital control system,after summarizing and analyzing the domestic and foreign digital welding power system architecture,the advantages and disadvantages of the single-stage control system and the two-stage control system are first discussed.Based on the variable polarity plasma arc welding power source structure,it is proposed A two-level control system architecture based on CAN bus is introduced.On the basis of this architecture,the peripheral circuits of the relevant digital controllers are designed around the power control unit and the process control unit,and the key parts of the circuit are simulated and verified using Multisim.On the basis of complete peripheral circuit design,and in accordance with the development process of general embedded systems,the demand analysis was carried out around the board-level support package of the digital variable polarity plasma welding power supply two-level control system,and the board-level support package of the welding power supply control system The structure of the system was discussed,a power control system board support package based on Stm32F107 and a process control system board support package based on Stm32F407 were designed,and the board-level support package migration strategy was proposed.Combined with the Simulink graphical simulation environment of Matlab,the simulation environment of the inverter arc welding power supply was built,and the power controller and the process control unit of the inverter power supply were simulated with the S function,and the arc welding was combined with the process controller and power controller.The external and dynamic characteristics of the power supply have been simulated experiments,and the parameter setting of the control strategy is optimized under the guidance of the simulation results,and good results have been achieved.On the basis of the board-level support package and the complete control algorithm,the software architecture of the power control unit and the process control unit and the task operation mechanism are designed.First,a multi-threaded operating environment based on a single-core processor is constructed,and on this basis,a top-down design mode is adopted,and object-oriented software design methods are applied to design the power control unit and other related functions of the process control unit.Class attributes and methods,complete the software design task of the power control unit and the software design task of the process control unit.Finally,the power load test and the welding process test of the test board were carried out through the load box.The power load test of the load box was used to test the current from small to large stages,and the current ripple size,adjustment time and overshoot were observed.And other main performance indicators.