This Genius New Axial Flux Motor Changes Everything

Lamborghini's new Temerario has not one, but three of the most advanced motors in the world. They are also cleverly integrated into the vehicle, providing over 440 horsepower. The motors concept was first developed in 2005, during a PhD at the University of Oxford, but has recently seen some considerable advancements, and variations of it are now inside some of the most powerful cars in the world. Not only that, but the design powered the world's fastest electric plane, and is transforming the world of propulsion as we know it. So, let's see how it works, what makes it so revolutionary, and how Lamborghini are implementing it. I'm Ryan Innes, and this is a Zero-G Dive. In this video, we'll cover why these Axial Flux motors are so power dense, the specific innovations making the motors used in the new Lamborghini unique, and the innovative way they have directly incorporated one of the motors into the V8 engine. I respect your time, so if you want to jump to any of those sections, the timeline is labelled to make it easier for you. Firstly, the incredible Axial Flux motor is the creation of the company YASA. It was founded by Dr. Tim Woolmer in 2009, after developing a prototype during his PhD at the University of Oxford in 2005. It is similar in principle to conventional Axial Flux motors, but with some interesting differences. Before diving in, it's useful to remember that electric motors work using magnetic fields. Inside a typical permanent magnet motor, the magnets are attached to the central rotating part, which is called the rotor. Surrounding this is the stator, which stays still and contains the copper wire windings. When we pass AC electricity through these windings, it creates a rotating magnetic field. This field pushes and pulls on the magnets in the rotor, causing it to spin. With electric motors, you can have radial or axial flux, with the flux just being the flow of something, in this case, magnetic fields. In radial flux, the magnetic fields flow from the middle to the outside, along the radius. In axial flux, it flows sideways along the axis. Kind of like if you had two pizza trays, where the magnetic fields would flow from one to the other as they span around. There is a bit of debate, however, around the claimed benefits of Axial Flux motors. Some people say that they offer higher torque and power densities, meaning that they have more torque or power for a given amount of weight. So, is that true? Well, sometimes. The torque densities are generally better, and that's because the magnets, which generate the rotating force in the motor, are further away from the middle. Just like how using a longer spanner gives you more leverage to undo a tight bolt, having these magnets further away from the centre gives them more leverage or moments to spin the motor. This therefore means that they can have higher torques for a given mass of motor. It's kind of like a built-in gear. Gears are interesting because they allow you to trade off between speed and torque. But because torque goes up as speed goes down, we always have the same amount of power, if we forget about any other losses. Now, Axial Flux motors have a similar type of consideration, because by increasing the size of the motor outwards, although it gives it more torque, it makes it harder to safely operate at higher speeds. This is because for a set speed, say 100 RPM, the further something is from the centre, the faster it must move to complete a full rotation. This faster speed pulls the magnet outwards with more and more force, causing stresses within the electric motor. This trade-off is, in part, why the power densities of Axial Flux motors are not always higher than in Radial Flux motors. The best Radial Flux motors can make up for their lack of torque by hitting extremely high speeds, and then just increase their torque later through a transmission, though this does add more weight and drops efficiency. Okay, so from what I've read, we can generally assume that an Axial Flux motor will have higher torque densities, but not always higher power densities. For example, Monroe & Associates recently tore down this Axial Flux motor from Omni Motors. Looking at its design, I would guess it doesn't have much of a power density improvement compared to a standard Radial Flux motor, but that doesn't mean it isn't useful. Higher torque without gearing and improved packaging are extremely beneficial. However, the Yasser Axial Flux motor in the new Lamborghini goes much further than this. It isn't your standard Axial Flux motor. The name Yasser actually tells us a lot about the motor used by Lamborghini, as well as many other supercar manufacturers, though Lamborghini's is a more advanced, custom-designed version. Yasser stands for yokeless and segmented armature, and is the breakthrough that Dr. Tim Walmer had during his PhD at Oxford. So, let's break it down. The yoke of an electric motor is the structural backbone that holds everything together and plays a crucial role in the motor's magnetic circuit. Typically made of iron or steel, the yoke surrounds the stator, which is the stationary part of the motor, and you can actually see it in the teardown from Monroe. It has two main purposes, mechanical support and magnetic flux guidance, which just means maintaining the correct flow of magnetic fields. It provides a sturdy frame that holds the motor's internal components in place, ensuring durability and reliability, but most importantly, completing the magnetic circuit by directing the magnetic fields that are generated by the stator and rotor. However, in the advanced yokeless design from Yasser, they found out a way to completely remove the yoke, massively reducing weight and improving efficiency. Part of the way they have done this is by using stronger bindings and material science innovations that make the stator strong enough without the yoke there. That is to say, there is a structural component there to hold everything together, but it isn't a heavy iron block and it doesn't interfere with the magnets. To make up for the fact that the yoke isn't there, they had to get a little bit more creative on how they controlled the flows of the magnetic fields. One way they did this was by using two permanent magnet rotors, one on each side of the yokeless stator. Not only does this increase the strength of the magnetic fields, which further boosts torque, it also guides the magnetic fields so the magnetic loops can be closed. Another change they made was to increase the size of the copper coils, so that they better aligned with the size of the magnets. This was described in a paper from Dr. Tim Walmer during his PhD, and I believe it was to help with the magnetic flows and structure and integrity, which as we know are important for the yokeless design. The second part of the name segmented armature refers to the armature, which is the motor that contains the copper coils. These carry the electrical current and generate the magnetic field needed for the motor's operation. Unlike traditional motors where the armature is a continuous structure, the yasser motor's armature is divided into separate, independent segments. This improves cooling as air and liquids can flow around the windings improving efficiency and therefore power density. We can also see that almost all of those copper windings which make up the electromagnets are inside the magnetic fields of the permanent magnets, meaning that they can all be useful for generating torque and power. If we compare this to a radial flux motor, we can see that the end windings stick out and therefore don't add to the motor's performance. In fact, we can see this in the motor torn down by Monroe too. This makes a key point that I want you to take away from this video. This yasser motor used by Lamborghini isn't your standard axial flux motor. When all is said and done, the yokeless and segmented design removes the need for 80% of the iron used within the stator. This is really where the world leading power density comes from, because they've gotten rid of so much of the dead weight. It's like how the power to weight ratio of a rally car can go up by stripping out all of the back seats and extra parts that are designed for comfort. The stats from the yasser motor are truly mind blowing, bringing up to 4 times more torque and double the power densities of current technologies used in most electric vehicles whilst being 50% lighter and just 20% of the depth of a typical radial electric motor. That graphic was from yasser motors however and I will say top of the range radial flux machines like those developed by lucid motors are starting to catch up in power density, though definitely not in torque density. The yasser motor specifically designed for Lamborghini benefits from all of these advancements but also uses new materials and designs to run at higher speeds than we have ever seen before. The yasser motor for the Temerario can run up to 10,000 rpm and is cleverly integrated into the powertrain. Two motors are placed at the front axle which is possible due to their thin design. These offer torque vectoring meaning each wheel has the perfect amount of torque to improve handling and performance. The third motor is then fully integrated into the V8 engine's housing which looks pretty awesome. Engineers integrated the electric motor into the housing of the V8 engine directly without an intermediate clutch. This fills any turbo lag no matter how small at any speed. The entire electric drive unit is located compactly between the combustion engine and the dual clutch transmission, meaning their speeds will be matched to give a natural feel. This electric motor also works as the starter motor and 3-phase generator. It's a similar setup to their 634 but with much higher speeds. Each motor weighs just 17.3kg and is 70mm thick. Not bad considering they each produce 110kW of power or 148hp. Impressively, these motors are all powered by a small 3.8kWh battery pack, meaning it is outputting some serious power for its size and must have some pretty impressive cooling. What's really exciting to me is that this means yasser are moving towards more volume production, something that has plagued axial flux motors due to the lack of manufacturing expertise and cost. I think we can all agree that the design and implementation of these motors is nothing short of genius, and if you've enjoyed my explanation, please consider subscribing, it's free. Now, designing and manufacturing these components takes a lot of precision modelling for simulations and machining, which is why engineers use computer aided design software like the product from Onshape who made this video possible. If you are an engineer, tinkerer or part of a business looking for an incredible computer aided design solution, then you need to check out Onshape, a professional grade CAD and product data management system designed to revolutionise how you design and manage your products. Imagine secure, real-time collaboration, multiple people working on the same design at once. 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