Abstract: The rapid development of aerospace science and technology is put forward higher requirements on the welding quality of aerospace aluminum alloy materials,and the digital variable polarity plasma arc welding power supply with the high performance is the key to improve the welding quality of aluminum alloys. In order to improve the dynamic regulation performance of the arc welding power source,based on single controller of Cortex-M4 kernel,the double closed loop feedback circuit of welding current and the transformer primary current were used,and the strategy of incremental digital PI control was employed in small signal and segmented quickly adjustment in large signal,and then a full digital VPPA welding power supply was developed with 20 kHz inverter frequency and stable welding current and excellent current response performance. The distribution and management in power control technology was investigated in detail,which includes the welding process control,digital constant current control,man-machine interface processing,and automatic controller communication and so on,and the load welding test under 280 A high current condition was carried out to verify the practicability and reliability of the power control technology.