Research On MOSFET Regulated Fast Charge And Discharge Precision Resistance Spot Welding Power Supply

Precision resistance spot welding is an important way to achieve connection of micro parts.Because of the small thermal inertia and the small temperature difference between the inner and outer surface of the micro parts,it is easy to melt the parts,not be melted properly,the quality of the welding is not stable,and the rate of finished products is low.Therefore,welding energy,electrode pressure and electrode shape must be controlled more precisely.The traditional micro parts welding power source is slow in welding energy rise speed,slow in energy control response speed and low in control accuracy,which is difficult to meet micro part’s welding requirements.Studying the more precise spot welding power source with energy control is of great significance to improve the welding quality of micro parts.Aiming at the special requirements of micro parts spot welding for spot welding power supply,a fast charge and discharge precision resistance spot welding power source based on MOSFET control is studied.It is not only improved the control accuracy and response speed of spot welding power,but also ensure the production efficiency of power supply.A fast charging circuit for capacitor banks based on half bridge inverter topology and a fast discharge circuit for capacitor banks based on Buck transform are used as the main circuit of power supply.The parameter design and selection of the key components in the main circuit have been completed.A control system based on DSC is designed,the design of drive circuit,sampling circuit,protection circuit and human-machine interaction system is completed;the design of PCB board for main circuit and control system circuit are completed.;the design of constant current charging control program,discharge control program and human-machine interaction program in control system software are completed.On the basis of the above work,a test platform is built,and the developed fast charge and discharge precision resistance spot welding power is debugged,and the constant current fast charging for capacitor banks is realized,and the steady constant current,constant voltage and constant power discharge waveform are obtained in a short time.The MOSFET type power supply is compared with the IGBT power supply,and the MOSFET type power supply is applied to the resistance spot welding of the micro parts.The result shows that the control precision and the response speed of the power supply are higher,the welding current is stable and rising fast,the ripple is small,and high quality welding can be achieved in a short time.