Motor development and manufacturing | Focus 71 finished stacks’ magnetic responses as they are supplied. They can then use these results to simulate/predict motor responses, which in turn allows them to optimise subsequent processes, such as winding and housing design, to maximise performance and shorten the design iteration cycle. For motors intended for use in a wide variety of vehicles and environments, particularly if they are off-the-shelf products, it is impractical to test for every condition it may meet in service, says one of our developers. “Probably, the biggest challenge for an off-the-shelf product is testing broadly enough for a lot of different applications, but deeply enough that you can stand behind your product and really feel confident in it.” Test standards such as ISO 16750, which sets out the environmental conditions and testing procedures for electrical and electronic equipment in road vehicles, provides a useful benchmark for planning tests, says another developer. However, to ensure planned tests match the risks presented by the design environment and the predicted behaviour of the system, they should be “thoroughly investigated” against the design failure mode and effects analysis (DFMEA), and the system failure mode and effects analysis (SFMEA), its expert says. (The DFMEA is a detailed analysis component design and function that looks for ways it could fail, and how such failures could affect the system as a whole. The similar SFMEA focuses on the entire system, and is used to assess potential failure modes, along with their causes and effects.) Motor performance is typically characterised by continuous and peak torque delivery, which are useful metrics for comparing motors and basic sizing. However, few motors are operated at either point in real-world applications, the expert adds. Traditionally, validation testing takes place late in development, which is a large source of risk if problems emerge. To reduce this risk, the company has invested heavily in simulation to evaluate performance and in its own in-house testing capabilities. “This allows early prototypes to undergo representative testing and subsequent feedback to be looped into the next design iteration.” The expert explains that motor and inverter testing and validation require dedicated, back-to-back dynos to characterise the motor throughout its operational envelope. Scaling up Manufacturing at scale can be seen as a continuum between what are essentially assembly and integration operations at one end to fully vertically integrated ones, with everything from raw materials to finished motors under the control of a single organisation, at the other end, but most fall somewhere in between. According to our soft, magnetic alloy and iron-cobalt stack specialist, the push for higher motor performance has led to the adoption of adhesive-based bonding and thinner laminations, in place of interlocking, in the automated manufacture of the latest-generation of EV rotor/stator cores. “The new e-mobility vehicles will require hundreds to thousands of stacks per model per year,” its expert adds. “We are working on new, automated stacking and bonding technology for larger-scale production. The use of robotic handling, machine vision alignment and feedback sensors will boost productivity, and improve the repeatability and quality of iron-cobalt stator and rotor stacks.” One of our developers makes its customised motors almost entirely in-house and in quantities of one to 100,000 without complex tools or high, one-off costs. “We even use our own wire-drawing machine to keep delivery times short and to be able to produce special wire geometries. The production of the active parts of the motor is our core business, with all production taking place in-house,” its expert says. Working with customers from development to production, the company has its own automation team. This enables it to realise fully automatic, fast production of X-pin, wave winding and hairpin windings in individual designs, and to react quickly to changing requirements. It can also automate the production of stators, rotors for synchronous and asynchronous machines, and the complete assembly of motors. “Almost exclusively, we use rectangular profile wires for the manufacture of our motors. This means we attach great E-Mobility Engineering | July/August 2024 Conductivity tests being carried out on a stator – an example of the component and sub-assembly testing that is essential to modern development and manufacturing processes. Manual and automated tests are appropriate at different stages (Image courtesy of Additive Drives)
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