| Digital arc-welding inverter, due to its flexible control, high control accuracy, strong stability, good consistency, and strong versatility, has become the main development direction of welding power supply in recent years. To digital arc-welding inverter, the good control scheme can ensure the stability and reliability of the integrated system. By comparing and improving the traditional control strategy, this paper proposes a new control strategy that is peak current and voltage dual-loop control with current feed forward, and designs the hardware and software of the power supply system. Through simulation and experimental analysis, the results demonstrate the effectiveness of the proposed control scheme. The main contents are as follows:(1) This paper proposes a new control strategy that is peak current and voltage dual-loop control with current feed forward. When the power supply is unloaded, the output current is zero, the outer current-loop is quickly saturated to the limit amplitude, and the inner voltage regulation is controlled by the constant voltage; When the power supply starts to arc, the outer current-loop exits the saturation, and the inner and outer loop jointly regulate the output to obtain the constant current control. After that, the system is modeled in a non-ideal condition. The simulation analysis shows the necessity of considering the non ideal factor, and the current feed forward compensation can improve the response speed of the system.(2) The arc-welding inverter design includes hardware and software design. In the design of hardware, the main circuit mainly includes inverter topology selection, high frequency transformer design and output filter inductor design. The control circuit is designed from three aspects, including sampling and conditioning circuit, IGBT driver circuit and protection circuit. For the software design, the control core is TMS320F28335. This paper focuses on the configuration of each module and the control flow chart to describe and analyze the design.(3) The system model of arc-welding inverter is built in the Matlab simulation environment. And by simulation and experimental analysis, the control strategy is verified to be able to timely adjust the transformer primary side current, rapidly response the switching between different states. Moreover it can quickly adapt to load changing, and ensure that the inverter power supply works stably without error. Above all, it is suitable for the situation that the speed and the accuracy of the output current have higher requirements. |
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