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How Tesla's 'Carbon-Wrapped' Motor with AFP could revolutionize electrification in Automotive

Introduction

Tesla's new carbon-wrapped motor has been making waves in the automotive industry, with many touting it as the most advanced motor in the world. This innovative technology is expected to provide increased efficiency, improved performance, longer battery life, and environmental benefits for electric vehicles. The carbon-wrapped motor could have been produced using Automated Fiber Placement (AFP) technology, a process used to manufacture carbon fiber-reinforced composite parts. AFP systems offer several benefits, including faster production times, improved efficiency, increased performance and strength, cost-effectiveness, and simplicity of operation. Tesla CEO Elon Musk has also praised the new carbon-wrapped motor, calling it the most advanced motor on Earth and promising to increase its torque and max rpm for the new Roadster. In this article, we will explore the benefits of the carbon-wrapped motor with probable AFP technology, as well as the benefits and limitations of Automated Fiber Placement systems.


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  • Increased efficiency

  • Improved performance

  • Longer battery life

  • Environmental benefits

A brief overview of Tesla's new carbon-wrapped motor

image showing no iron bridge between the magnets [1]
image showing no iron bridge between the magnets [1]

Carbon fiber is a good option for wrapping rotors since it is a poor conductor and almost free from eddy losses. However, carbon fiber is not an ideal choice for thermal management, as it does not expand, and the rotor will apply a larger pressure on the magnets when the motor is stationary.



Tesla's Plaid motor uses a fiber sleeve to hold the rotor in place instead of the typical bridges. This eliminates the leakage flux path and allows the rotor to spin at higher rpms. The sleeve appears to be quite thick, meaning the motor has a magnetic air gap bigger than the typical 1.5mm seen in traction-IPMs.



In conclusion, Tesla's Model S Plaid will apparently use carbon fiber retaining sleeves in their motors, but this is not entirely accurate. The motor uses fewer or no bridges at all in the rotor, which reduces the mechanical clearance between the stator and rotor and/or increases the magnetic air gap.


Importance of ‘Carbon-Wrapped’ Motor in the automotive industry

Having a lighter rotor wrapped with strong carbon fiber in electric motors could have a lot of benefits for the electrification of the industry:

  1. Increased efficiency: A lighter rotor requires less energy to spin, which means that electric motors can run more efficiently. This is because electric motors convert electrical energy into mechanical energy, and a lighter rotor requires less electrical energy to achieve the same amount of mechanical energy.

  2. Improved performance: Lighter rotors with strong carbon fiber wrapping can provide improved acceleration, top speed, and handling for electric vehicles. These benefits are particularly important for sports cars and high-performance electric vehicles.

  3. Longer battery life: With a lighter rotor, electric vehicles require less energy to move, resulting in increased range and longer battery life. This is particularly important for electric vehicles, which rely on battery power to run.

  4. Environmental benefits: A lighter rotor wrapped with strong carbon fiber means less material is required to produce the rotor, resulting in a reduction in the carbon footprint of electric vehicles.

A lighter rotor wrapped with strong carbon fiber in electric motors increases efficiency, improved performance, longer battery life, and environmental benefits.



Carbon-wrapped motor with AFP technology

High-tension carbon overwrapping is a process that involves winding continuous fiber tapes of carbon fiber prepreg at high tension around a mandrel or a part to add an extra level of considerable strength, substantially increasing the component's capacity for speed and endurance without adding significant weight. This technique is commonly used in the aerospace and automotive industries to produce high-performance parts and structures.

AFP winding motor rotor with high tension carbon fiber
AddPath simulation showing AFP winding motor rotor with high-tension carbon fiber wrapping

Automated Fiber Placement (AFP) is a process used to manufacture carbon fiber-reinforced composite parts. It involves using continuous fiber tape and digital tension control mechanisms mounted on a robotic arm, and layup up parts according to a pre-programmed winding pattern. AFP systems can generate up to 2000 Newtons of tension and wind consistently in up to 2 m/sec. Winding at high tension allows manufacturers to pack fibers more tightly and uniformly around a mandrel or part, pulling the fibers closer together within the winding pattern.


The carbon fiber overwrap can be applied to various parts, including rotors for electric motors, driveshafts, and suspension components, among others. The AFP solutions are capable of processing single- or multi-tow carbon, glass, or ceramic fibers and can accommodate dry winding, wet winding, and thermoplastic or thermoset prepreg and tow pregs. The result is a lightweight and durable composite part with an excellent strength-to-weight ratio and fatigue resistance.


Benefits and limitations of Automated Fiber Placement systems

It is important to note that while there are benefits to using AFP systems, there are also limitations to consider. It is important to weigh the pros and cons of using AFP in a specific application to determine if it is the right choice for a particular project. In some cases, the benefits of faster production times, improved efficiency, increased performance and strength, and cost-effectiveness may outweigh the limitations such as size and material constraints. In other cases, manual processes may be a better fit depending on the specific requirements of the project. It is important to carefully assess the needs and capabilities of a project before deciding on the best manufacturing approach.

  1. Faster production times: The AFP process involves laying down unidirectional fibers in a pre-programmed pattern, rather than manually placing individual strands. This can reduce production times by up to 40%.

  2. Improved efficiency: AFP can improve efficiency and reduce material waste compared to traditional manual hand layup processes.

  3. Increased performance and strength: AFP produces more consistent results than manual hand layup, resulting in stronger bonds between layers and improved performance and strength in the finished product.

  4. Cost-effectiveness: The improved efficiency and reduced material waste associated with AFP can make it a more cost-effective option compared to other manufacturing processes.

  5. Simplicity: Any graduate student knowing the basics of composites can easily operate the latest AFP system without requiring a high level of technical knowledge and expertise to program and operate the equipment.

  6. Accessible: AFP-XS fiber placement systems can be very easy to acquire and can be operational within days, making it a compelling choice for smaller manufacturers.

  7. Shapes: AFP systems can work as tape winding and filament winding systems, capable of producing highly complex shapes with complex fiber orientation

  8. Material: AFP systems can work across thermoset, thermoplastic, and dry fabrics, allowing much greater freedom in material selection

  9. Health and safety: Moving the operator away from the composites processing environment ensures better health conditions and lowers the consumables requirements.



However, there are also some limitations to consider when using AFP systems:

  1. Size limitations: AFP systems may not be suitable for parts with a very small or intricate geometry e.g. a watch case, small hinge, etc. as the tows may not be able to be placed accurately in these areas.

  2. Material costs: Materials used in AFP processes are relatively expensive i.e. 10-15% higher cost compared to the materials used in manual processes.

Elon Musk on the new carbon-wrapped motor



Future outlook

Looking into the future, the carbon-wrapped motor with AFP technology offers exciting opportunities for the automotive industry. The use of this innovative technology has the potential to revolutionize electric vehicles by increasing efficiency, improving performance, and reducing their carbon footprint.


One of the biggest opportunities is the possibility of making electric vehicles more accessible to a wider range of consumers. The improved efficiency and longer battery life provided by the carbon-wrapped motor with AFP technology can help to make electric vehicles more cost-effective and practical for everyday use. As electric vehicles become more accessible, the demand for them is likely to increase, leading to further innovation in the field.


Another opportunity is the potential for carbon fiber composites to replace traditional materials such as steel and aluminum in the manufacturing of automotive parts. Carbon fiber composites offer a lighter and stronger alternative to traditional materials, which can lead to improved fuel efficiency, range, and performance. This can also lead to a reduction in the carbon footprint of the automotive industry.


Moreover, Automated Fiber Placement technology is constantly improving and becoming more accessible. This means that smaller manufacturers will be able to afford and easily acquire AFP-XS fiber placement systems, allowing them to produce high-quality composite parts without the need for a high level of technical expertise or knowledge.



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