Digital Control Strategy Research and Implementation of PMIG Arc Welding Power Source
|Course||Control Science and Engineering|
|Keywords||DPWM PMIG welding FIR digital filter FPGA MCF52259|
Digitized inverter welding power source than traditional analog welding power supply can effectively improve the welding efficiency and quality of welding, and thus become the trend of the development of the field of welding. Welding power need to overcome a number of technical problems in a process controlled by the analog to digital, digital PWM drive and protection functions, welding signal sampling and denoising control policy choices, real-time data processing capabilities, embedded technology and development of EDA technology provides a new method for the solution of these difficulties. Through the analysis of the formation mechanism of the signal characteristics of the welding current and noise, that the high-frequency operation of the power switching device the major sources of interference of the welding signal, and speed FIR digital filter is designed for this high frequency noise on the current signal after sampling digital filtering to improve the accuracy of the digital signal; analysis of current and voltage PWM control principle, combined with the current characteristics of the transformer primary side and secondary side, the design of the secondary current feedback, the peak current protection current DPWM control The strategy to achieve high-precision PWM pulse output and main circuit overcurrent protection. Designed on the basis of analysis of the welding quality PMIG solder droplet transfer mode and pulse waveform loop control strategy based on the segmented current PI regulator, precise control of welding output current, a pulse and a drop droplet transition forms; requirements for the control of the welding arc, designed to limit the real-time pulse frequency arc length regulation strategy sync pulse arc length adjustment can be completed in a single cycle; In order to simplify the welding parameter settings and convenient operation, according to the relationship between the welding parameters determine the parameters of unified regulation scheme, by setting the welding voltage, the system can automatically give the other welding parameters; combined with the current trend of the development of welding technology, designed to control USB and Ethernet-based welding parameters, data storage solutions U disk and Ethernet given welding parameters and welding current and voltage data storage. For determined welding signal extracted control and driving strategy, the main control system using the FPGA chip as the main control unit, and embedded in of 32 NiosII processor. FPGA internal DPRAM by building a large number of data interaction between the realization the various functional module with NiosII of processors; welding process based on the Verilog hardware description language function module is responsible for all the algorithms and data processing, including voltage and current double closed-loop control, the data sampling filter processing, DPWM drive and welding process control and signal control speed, data throughput advantages of control; embedded processor based on the C language development NiosII FPGA with external data communication and welding timing control is responsible for , more flexible way of communication and control of the master system. Digital tube LED display panel hardware displayed, enter the rotary encoder combines key to achieve a rapid adjustment of the remote display of welding data and parameters. Hardware for communication programs to achieve platform selected MCF52259 chip integrated USB and Ethernet module, simplifying the circuit design, reliable technology. Digitized PMIG welding power supply control system design module function test, under the premise of ensuring each module is reliable and stable welding test. The test results show that the combustion stability under the control of the the digitized arc welding power supply system design, the welding arc, droplet consistent weld dense uniform.