Research And Design Of Resistance Welding Power Supply Based On The FPGA

At present,the resistance welding power in the market is mainly controlled by MCU and DSP chip,and the working frequency is generally in the 1 kHz ~ 2 kHz.As the resistance welding owns the special characteristics like large welding current and short welding time.In order to satisfy the higher requirements of welding process and welding quality in industrial manufacturing,the new requirements for the control of resistance welding power are put forward.It is proposed that the process control is more stable and reliable,and the welding input energy can be controlled precisely.Compared to single chip microcomputer and DSP,FPGA chip has advantage in real time and control precision.Therefore,this paper uses the FPGA chip as the control core to research and design resistance welding power.In order to obtain high control precision and good real-time,each functional module of the constant current controller of the power is designed by employing the characteristics of the FPGA parallel architecture,specifically,the digital PID is improved.For the sake of avoiding the current shock when the power supply is switched on and the current value is switched,soft handoff module is adopted.In this paper,the basic principle and welding process of resistance welding are analyzed in detail.Then the overall design scheme of the power supply is determined,including analyzing and designing the main circuit,selecting the key components and confirming the parameters.At last,based on the 2SD315 A module,the driving circuit of high power IGBT is researched and designed.In addition,in order to ensure safe and reliable operation of the whole system,this paper also designs the power protection circuit,current feedback circuit.And the asymmetric gate circuit is analyzed and designed for improving the driving effect.Lastly,under the condition of different loads,the timing simulation of the designed constant current controller is done in Modesim,and the simulation results are satisfactory.By testing the driving pulse of power IGBT,the experimental results show that the driving pulse can be reliably driven by IGBT.At the same time,under no-load condition,the test results of the transformer are good.And the simulation test of each functional module of the power is done in Simulink of Matlab,the simulation results further tested the reliability of the design.