This paper explores the weldability of 1xxx and 6xxx series aluminium (Al) round wire welded to a range of Al and copper (Cu) plates to represent busbar and terminals for remote laser welding (RLW) and ultrasonic welding (USW), respectively. The motivations for materials are discussed and evaluated from a performance and high-volume manufacturing perspective for low-cost traction motors. The welding processes are assessed for their suited winding schemes. This paper proposes a novel approach of using USW to weld multiple thicker conductors with the aim of producing stranded wire terminations, similar to that commonly used for wire harnesses. The paper also proposes an alternative weld configuration as the main contribution for RLW. This utilises an axially focused laser beam direct to the interface between the wire and busbar. The aim is that this will improve the weldability of the Al-to-Cu specimens without the use of filler wire, commonly adopted in these scenarios, in addition to simplifying manufacturability. Lastly, the paper reviews the results of the proposed methods and discusses the manufacturing implications.
Motivated by the need for higher torque density actuators in novel (quasi-)direct-drive robotics applications, a Yokeless and Segmented Armature Axial Flux Permanent Magnet Synchronous machine with anodised aluminium foil conductors instead of enamelled copper wire is considered in this work. Based on a requirements analysis of (quasi-)direct-drive actuators, a prototype axial flux machine is designed. Several design aspects are discussed keeping the application requirements in mind. It could be concluded that the combination of the machine topology and conductor material results in a high fill factor and excellent thermal properties, making it particularly promising for high torque density, low speed applications. A prototype was manufactured to demonstrate the feasibility of the design. The interconnection of aluminium foil to copper wire appeared to be challenging, two interconnection methods were tested and compared qualitatively.
The radical transformation of the automotive industry away from the combustion engine and towards the electric drive requires a constant development and improvement of the related components and production processes. One of these processes is the partial removal of the insulation from copper wires in the production of hairpin stators. Currently, the deinsulation is done by mechanical or laser-based methods. The laser-based process is considered to be a comparatively cost-intensive method, whereby stripping rates can be achieved with almost no copper removal independent of variations within the insulation layer thickness of the original copper wire. Mechanical processes, on the other hand, are sometimes seen critically, since a mechanical process always involves a certain amount of removal of the copper raw material to ensure that the insulation layer is completely removed even if the layer thickness varies due to material and manufacturing based tolerances. A critical limit at which copper removal has a negative influence on product functionality has not yet been identified. Therefore, this work focuses on the effects to which the critical process of contacting the hairpins is influenced by the reduction of the copper cross section. For this purpose, hairpins of the same batch are mechanically stripped to different depths, resulting in different reductions of the copper cross-section. The samples are then welded with a constant set of parameters. The varying stripping depths result in both a variation of the copper cross-section and a variation of the gap width between the pins during welding. All other process parameters are identical for all the samples. The welding samples are then metallurgically analyzed and the mechanical, thermal and electrical properties are measured. These results are then analyzed regarding possible interdependencies and evaluated in the context of possible influences on the functionality of the electric drive.
Especially in the production of electric drives, highly efficient drives in new use cases are needed to reach global climate targets. To obtain maximum motor power with minimal motor weight, it is necessary to fill the stator slots with a maximum of copper. In the past, the round wire has been the state of the art. However, with increasing efficiency expectations, round wires cannot reach the performance targets anymore. Form coils, also known as hairpins, are one common technology with higher fill factors. In addition, winding processes with endless flat or rectangle wires are currently in development and could fulfill the demand for electric drives in the future. Accompanied by new joining solutions, this technology could lower the production cost on the one hand and reduce the contacting spots with potentially increased contacting resistance on the other hand. One challenge in the automation of their winding and joining is a fully automated process chain, starting with the winding process and ending with end-of-line testing. One thing, all process steps have in common is the requirement to detect the position of the wires with high precision. This detection is fundamental to subsequent steps, performed by smart robot-based machines.
In this paper a novel approach is presented to tune the application of sensorless control strategy based on the model reference adaptive system method (MRAS-based). Thus the influence of multiple parameter variations on the control is balanced. The method was used for speed and position estimation of a field-oriented controlled (FOC) wheel hub drive with an axial flux permanent magnet synchronous motor (AFPMSM). Parameter deviations could be described mathematically as disturbances of the MRAS scheme. Their influences are reduced by an enhancement of the fundamental wave model. The investigated tuning method compensates the mean value of the flux orientation angle error of the sensorless control caused by parameter variations using these occurring disturbances. In order to investigate the proposed method, a model-based system engineering (MBSE) approach was chosen to compare simulation and experimental results. The simulation study of the control strategy was performed using MATLAB®/Simulink®. Further on, the MRAS-based method was implemented on a target system directly from the simulation model using code generation software. A performance evaluation of the tuning application boundaries is focused on accuracy, sensitivity and stability of the control. The dynamic response can be calculated.
