In aerospace and new-energy vehicle manufacturing, there is an increasing demand for the high-quality joining of large, curved aluminum alloy structures. This study presents a robotic friction stir welding (RFSW) system employing a force/position hybrid control. An eight-axis linkage platform integrates an electric spindle, multidimensional force sensors, and a laser displacement sensor, ensuring trajectory coordination between the robot and the positioner. By combining long-range constant displacement with small-range constant pressure—supplemented by an adaptive transition algorithm—the system regulates the axial stirring depth and downward force. The experimental results confirm that this approach effectively compensates for robotic flexibility, keeping weld depth and pressure deviations within 5%, significantly improving seam quality. Further welding verification was performed on typical curved panels for aerospace applications, and the results demonstrated strong adaptability under high-load, multi-DOF conditions, without crack formation. This research could advance the field toward more robust, automated, and adaptive RFSW solutions for aerospace, automotive, and other high-end manufacturing applications.

Multi-output power converters using different architectures can have significant efficiency advantages. This paper proposes a multi-output welding power supply that is based on the middle DC converter distributed architecture. This machine includes two converter groups, and each group comprises a three-phase rectifier unit, a full-bridge converter unit, a HF (high frequency) transformer, a rectifier unit, and a chopper converter unit. Among these units, the three-phase rectifier unit, full-bridge converter unit, HF transformer, and rectifier unit convert three-phase AC voltage into a low voltage, and the chopper converter unit converts the low voltage into the required current. The welding power supply can output four DC and two AC currents. This paper also analyzes the stability of the welding power supply. Finally, a prototype is designed and verified through experiments, and the maximum output of the prototype is 300 A. The experimental results show that the converter can output different DC and AC currents according to the requirement, the multiple outputs are independent of the others, and the output phase and value are independently adjustable. After verification, the proposed multi-output welding power supply can output steady current according to the requirement.

In aerospace and new-energy vehicle manufacturing, there is a growing need for high-quality joining of large, curved aluminum alloy structures. This study proposes a robotic friction stir welding (RFSW) system employing force/position hybrid control. An eight-axis linkage platform integrates an electric spindle, multi-dimensional force sensors, and a laser displacement sensor, ensuring precise robot–positioner trajectory coordination. By combining large-range constant displacement with small-range constant pressure—supplemented by an adaptive transition algorithm—the system regulates axial stirring depth and downward force. Experiments confirmed that this approach effectively compensates for robotic flexibility, keeping weld depth and pressure deviations within 5% and significantly improving seam quality. Further welding verification was conducted on typical curved panels for aerospace applications, results demonstrated strong adaptability under high-load, multi-DOF conditions with no observed cracks. This research could support advance the field toward more robust, automated, and adaptive RFSW solutions for aerospace, automotive, and other high-end manufacturing applications.

Dual Active Bridge (DAB) converters are more commonly deployed in renewable energy systems, electric vehicles, advanced energy storage, and distributed power grids than conventional DC-DC converters due to the advantages of electrical isolation, high power density, and zero voltage switching (ZVS) capability. Existing studies on DAB mainly focus on conduction loss, reflux power loss, current stress, and high-frequency oscillation based on ideal states, which do not thoroughly consider the dead-time effect. As switching frequencies increase, dead-time causes severe operational hazards such as voltage polarity reversal and voltage sag, potentially damaging power devices. However, existing research addressing dead-time is limited to basic control strategies. To extensively exploit the performance potential of DAB converters, this paper proposes a current stress-optimized Variable Mode Extended-Phase-Shift (VM-EPS) control scheme that explicitly considers dead-time effects. By deriving exact operational characteristics across ten non-ideal modes, the proposed scheme coordinates specific operating modes for light, medium, and heavy load scenarios. By formulating and solving the current stress optimization problem using the Karush-Kuhn-Tucker (KKT) method, optimal phase-shift and dead-time ratios for each mode is designed and eliminates dead-time-induced voltage hazards across the approximate full power range. To summarize, the optimized control achieves approximate full-range ZVS, enabling true soft-switching operation. Experimental validation confirms the effectiveness of the proposed method in eliminating voltage hazards, optimizing current stress, and enhancing the overall performance of DAB converters.

Welding technology is a key aspect of the manufacturing industry. With the application of aluminum alloy expanding to more applications, the demand for advanced welding technology for aluminum alloy is constantly increasing. The aluminum alloy welding process requires a multi-output welding power supply to improve aluminum alloy welding quality. In this paper, we design a novel type of multi-output converter that outputs dual DC or single AC according to different welding process requirements and analyze its working principles in detail. Considering the influence of load current variation on the circuit’s performance, we established small-signal models of the DC and AC working modes and large-signal models of the system. Based on these models, we designed a control algorithm for the proposed multi-electrode arc welding power supply. Finally, we constructed an experimental prototype and demonstrated the feasibility of the control strategy. Based on the welding power supply designed in this paper, the welding process control of aluminum alloy can be more accurate, resulting in better welding quality.