Arc welding inverter with embedded Digital Active EMI controller

Digital high-frequency arc welding inverter is widely used in welding areas because of its many advantages such as high efficiency, small size, easy to control etc. However, with the development of high frequency of the switching, the conducted EMI generated by arc welding inverter becomes increasingly serious, especially common mode conducted EMI. Based on Digital Active EMI Filter (DAEF) controller, this paper proposes a new method which can reduce common mode conduction EMI for arc welding inverter. It is a closed EMI control loop by sensing EMI signal, sampling, digital compensation control, DAC output and injection. The EMI control can be embedded in original controller of arc welding inverter to reduce costs. Moreover, since there is no component in series connect with the power circuit, DAEF solves the problem of traditional EMI filter in filter size and power consumption fundamentally. In this paper, the arc welding inverter system with DAEF is designed, molded and compensated. Meanwhile, by simulation and analyses, the advantages of arc welding inverter with DAEF in system stability and dynamic performance are showed. Finally, experiment results showed that the proposed method has advantages in reducing conducted EMI emission and improving dynamic performance of arc welding inverter.