48 applications invariably require more sophisticated liquid cooling systems, potentially even incorporating airconditioning chillers to maintain optimal operating temperatures. In this realm, performance takes precedence, often in lower-volume, high-margin vehicles such as sports cars or luxury models. This allows for implementation of more intricate and costly cooling systems with complex cooling channel geometries and additional heat exchangers to ensure uniform temperature distribution. Valeo’s expert outlines specific challenges in high-performance EV cooling. Heat accumulation during continuous high-speed driving in the motor and power electronics, coupled with heat generation in the battery during fast charging, can push the entire system toward critical temperature thresholds. Furthermore, component interaction poses another challenge because the thermal loads of the motor, power electronics and battery can influence each other, making it difficult to optimise cooling for each component individually. For instance, a hot motor can negatively impact the cooling efficiency of the battery if they share thermal management resources. To address these challenges, Herman emphasises holistic thermal management, employing integrated systems with multiloop cooling circuits dedicated to the motor, battery and power electronics. These advanced systems often feature adaptive cooling, where coolant flow rates and temperatures are adjusted dynamically based on real-time data from thermal sensors. Cooling system integration, where cooling channels are shared strategically between components like the motor and the inverter can also improve overall system efficiency. Finally, advanced heat exchangers, such as multi-layered or hybrid air–liquid systems, can more effectively manage heat from diverse sources. Odling focuses on the perspective of the motor in high-performance scenarios, emphasizing the challenges posed by repeated acceleration cycles and long-duration high-speed runs, especially when followed by rapid charging without an adequate cooldown time. These continuous operating demands are critical performance metrics for high-performance vehicles. Cooling with AI Rapidly becoming ubiquitous, artificial intelligence (AI) is beginning to impact motor cooling with, for example, generative AI now creating elaborate and very efficient paths for fluid channels within motor housings and cooling plates, Uppuluri notes, cautioning that ensuring they are manufacturable at a cost appropriate to the application is crucial. Also, he expects that AI will help significantly with overall motor design, particularly in optimising a system with several variables, such as the number of windings, the size of the air gap between rotor and stator, the number and position of nozzles for directing cooling oil flow. “Optimising across all of this without the acceleration from AI takes a very long time,” Siemens’ expert says. Herman adds that AI will support multi-physics coupled simulation tools for generative design, taking magnetic, mechanical, noise–vibration–harshness and thermal behaviour into account. Ultimately, AI and machine learning, she says, will revolutionise EV motor thermal management by offering predictive cooling strategies, in addition to predictive diagnostics and optimisation of energy use. Electrohydrodynamics and ‘superconductivity’ More broadly, Herman anticipates that the next decade or so will be shaped by the emergence and maturing of new technologies. One of these is electrohydrodynamic (EHD) cooling, which uses electric fields to drive the flow of fluids or gases at the microscopic level, thereby enhancing heat transfer, particularly in motors and power electronics. Developed to cool electronics, EHD cooling does not need mechanical pumps, meaning that it could enable simpler and more reliable systems capable of highly targeted cooling in areas with concentrated heat generation, such as motor windings. Without mechanical parts, EHD cooling could also reduce the overall energy consumption of thermal management systems. However, significant challenges remain, notably the current low efficiency of EHD cooling when scaled up for larger systems such as EV motors and batteries. Moreover, the technology is still in the early stages of r&d, requiring further maturation before it can be considered viable for massmarket applications, Herman cautions. Another emerging technology is thermally ‘superconductive’ cooling systems based on graphene and/or carbon nanotubes. Both offer disruptive potential for EV thermal management by virtue of their exceptionally high intrinsic thermal conductivities, she emphasises. Their superior mechanical strength and flexibility compared with established heat transfer materials allow for integration into complex geometries, and provide enhanced durability under vibration and thermal cycling. Furthermore, the ultra-thin and lightweight nature of graphene could lead to highly efficient and compact coolers for use in spaceconstrained motor housings. Insight | Motor cooling May/June 2025 | E-Mobility Engineering Coolant pipe connection on the casing of an axial flux motor from YASA, known for direct oil cooling of copper windings (Image courtesy of YASA)
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