This one change could make motors smaller, lighter, and more powerful

In our latest episode of Lexicon, we sat down with Manuel Hartong, CTO of Dynamic E-Flow, who breaks down why that gap exists and why it matters more than most people realise. Electric motors are efficient, reliable, and already embedded across industries from automotive to aerospace. But as Manuel Hartong makes clear, there is still a fundamental constraint holding them back: heat. Read on to find out more. Also, subscribe to IE+ for premium insights and exclusive content! Electric motors are efficient, but not perfectly so. The heat generated in the copper windings has to go somewhere. “Many materials that are electrically insulating are also thermally insulating,” Hartong told us. In conventional designs, the heat must travel through multiple layers of insulation, structural materials, and air gaps before it reaches any cooling system. By the time it gets there, the damage is already done. “To cool it, typically you have a water jacket around the motor. But between the wires and the cooling medium, you have many layers,” he explained. This creates a fundamental limitation. Motors can deliver high peak power, but only for a short burst. “Typical car motors can run at peak power for 30 seconds, maybe a minute,” he said. After that, output has to be reduced. For applications like electric aircraft, that limitation becomes critical. “If you imagine a plane taking off, it needs to go longer than that,” he added. How you cool matters To help solve this, most cooling systems focus on removing heat from the motor as a whole. However, Hartong argues that this is fundamentally inefficient. “Cooling the motor instead of the source is like trying to put out a fire by cooling the room,” he explained. It is a simple analogy, but it captures the issue well. The heat is generated in the windings, yet most cooling systems only interact with the outer structure. The longer the thermal path, the greater the resistance, and the higher the internal temperatures. This is where Dynamic E-Flow takes a different approach. Cooling the source Hartong and his team believe that instead of cooling around the motor, the focus should be on cooling the windings directly. Their solution replaces traditional solid conductors with hollow ones, allowing coolant to flow through the wire itself. “The wire itself is a hollow structure, and the coolant is in direct contact with the copper,” he said. This, he explained, changes everything. So, by removing heat at the exact point where it is generated, the thermal bottleneck disappears. “If you remove the heat from the wire, you don’t have this peak performance limit,” he added. The result is a motor that behaves very differently from conventional designs.“With direct cooling, there is no difference between peak and continuous power. It’s the same,” he said. Redefining power density One of the most immediate impacts of direct cooling is the ability to push current densities far beyond traditional limits. Conventional motors typically operate within a constrained range due to thermal considerations. Remove that constraint, and new possibilities emerge, he explained. “We are not talking about some percent. We are talking about half the size or two to three times the power,” he told us. This leap in power density opens the door to entirely new system architectures. Motors can be smaller, lighter, and more responsive, or they can deliver significantly higher output within the same footprint. For industries like aviation, where weight directly translates to cost and capability, the implications are profound. “If it’s half the weight, then you can take more passengers,” he added. Designing without thermal limits Perhaps the most interesting part of Hartong’s work is not just the performance gains, but the shift in how engineers can think about design. “If you remove thermal limits, you can design motors completely differently,” he said. In traditional motor design, thermal constraints are a dominant factor. Engineers must constantly balance performance against heat. Remove that constraint, and the design space expands dramatically. “You are no longer designing around heat. You are designing around the application,” he added. This freedom, he explained, leads to unconventional but highly effective solutions. In some cases, efficiency is deliberately sacrificed to achieve other goals. “You can make a motor inefficient on purpose, just to make it smaller and lighter,” he explained. It is a counterintuitive idea, but one that reflects a more system-level approach to engineering. Real-world impact While electric aviation is an obvious beneficiary, Hartong highlighted several other industries where direct cooling could have an immediate impact. Marine systems are a prime example. Large ships rely on massive generators and motors that are often difficult or impossible to remove for maintenance. “A large generator in a ship often can’t even be removed. It has to be cut out,” he said. So, by reducing size and improving modularity, direct cooling could transform how these systems are serviced and maintained. “If you make it smaller, you can actually take it out, service it, and put it back,” he added. Industrial applications, particularly those requiring sustained high power, also stand to benefit. Unlike passenger vehicles, which rely on short bursts of peak power, systems like trucks, ships, and test benches demand continuous output. “For industrial applications, you need the power for a long time,” he said. Reliability and lifetime gains Beyond performance, direct cooling also addresses another critical issue in electric machines. Long-term reliability. “Heat cycles are one of the main reasons motors fail,” he said. Repeated heating and cooling cause materials to expand and contract, gradually degrading insulation and structural integrity. By tightly controlling temperature, these effects can be significantly reduced. “If you control temperature tightly, you dramatically increase lifetime,” he said. Hartong notes that conventional motors can reach temperatures of around 356°F (180 degrees Celsius), while directly cooled systems can deliver higher performance at much lower temperatures. “Our motors typically have maximum temperatures around 120 degrees, even at higher power,” he added. This reduction in thermal stress not only improves reliability but also reduces maintenance demands over time. “You can really approach design from a completely different level,” he said. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Christopher graduated from Cardiff University in 2004 with a Masters Degree in Geology. Since then, he has worked exclusively within the Built Environment, Occupational Health and Safety and Environmental Consultancy industries. He is a qualified and accredited Energy Consultant, Green Deal Assessor and Practitioner member of IEMA. Chris’s main interests range from Science and Engineering, Military and Ancient History to Politics and Philosophy.