Research Of Intelligent Control System Of Spot Welding Inverter Power Based On DSP

There are many advantages of inverter welding power, such as small volume, littleweight, low energy, high efficiency, good electrical performance, easy to realize intelligentcontrol and so on, so inverter welding power has been an inevitable trend of welding power.The paper put forward the soft switching circuit topological structure and digital, intelligentcontrol method through the analysis on the present situation and existing problems ofdomestic and foreign inverter welding power, which provided theory basis for thedevelopment of inverter welding power to be high efficiency and intelligent.In the present time, the main circuit of spot welding inverter power in the practicalapplication is hard switching. The big switching stress and high loss of the switchingdevices lower the power efficiency. However, the research on soft switching techniqueindicated a new method to solve the problem. Through the comparative analysis of kinds ofsoft switching circuit topological structure, the main circuit of phase shifting-fullbridge-zero voltage zero current (PS-FB-ZVZCS) was selected. The paper introduced therealizing process of soft switching, circuit model and parameters design of key componentsin detail. The control core was digital signal processor (DSP), and in the practical system,collecting the real time load current(in the hardware circuit, collecting the voltage of theresistance), dealing with it according to the algorithm and then output correspondingphase-shifting PWM to drive the switches to realize the constant current control. In view ofthe drawbacks of traditional PID, The paper put forward a new control algorithmFuzzy-Neural Network-PID. When detecting inputs, computing them according to fuzzyneural network, output three corresponding matching parameters of PID, and then doingPID control, meanwhile, feedback the error between the reference and the output of thesystem to fix the connecting weights, and finally realizing the real time adjustment in linewith the status of the system.The article built the system model of spot welding inverter power, and achieved theintelligent control algorithm of fuzzy neural network PID on line. Designed PWM drivingcircuit and sampling circuit, introduced their working principle, produced phase-shiftingPWM of DSP to drive the whole bridge circuit, and fulfilled the constant current control ofinverter power. The results indicated that, Fuzzy-Neural Network-PID algorithm could achieve theparameters of PID matching and constant current control according to the running system,which had certain significance to the development of the intelligent control technology ofthe spot welding inverter power.