Tesla Fundamental Engineering Improvements for About 50% More Efficiency Than Competition

Elon Musk recently tweeted out on December 2nd and mentioned that the current efficiency of the Tesla semi is 1.7 kWh per mile. He also mentioned that there is a clear path to 1.6 and possibly 1.5 kWh per mile. One gallon of gas is equal to around 33.7 kilowatt hours of electricity. This means a fully loaded Tesla Semi is getting about 20 MPGe (equivalent). A Tesla Cybertruck will likely get 0.3 to 0.5 kWh per mile of loaded range when the load does not greatly reduce the aerodynamics.

Tesla is using many new technologies to enable them to work with stronger magnetic fields, higher voltages, more RPMs and better heat management and lighter weight and easier to manufacture parts.

Although, the following chart shows that the best-competing semi trucks have 20% less efficiency at 1.9-2.0 kWh per mile. Those are with far less driving range and less batteries. It will reduce the efficiency of a Freightliner ECascadia from 1.9 kWh per mile to 2.0 kWh per mile to go from 150 miles of range to 220 miles of range. Going from 220 miles of range to 530 miles of range under load could reduce the efficiency to 2.2 kWh per mile. The new Tesla technologies show they are on track to 1.5 to 1.6 kWh per mile efficiency in the Semi and high efficiency in all of their other vehicles including the Cybertruck. Tesla Model S/X/3/Y have had about 30%+ more energy efficiency than competing electric cars for over ten years.

Tesla is continuing to improve its engines, batteries and drivetrain. The voltage increases discussed in this article will increase efficiency in multiple ways.

There is another article where I over the advantages of Tesla’s new hairpin motor stators and new M3P batteries.

The Tesla Semi motors and powertrain will be used in at least the three and four-motor Cybertrucks.

The low-voltage system in gas and electric cars has been 12 volts since the 1950s. Tesla is going to 48 volts for the lower power and 1000 volt for the power train. The electric vehicle high voltage power train has mostly been 400 volts.

Here are a couple of videos discussing the efficiency and effects of the 1000-volt systems.

Sandy Munro discusses the 48-volt low voltage system at the 35-40 minute point in the video below. You can reduce the copper in the wiring for the low-voltage system used for locks, switches and other systems. Efficiency is increased and weight is reduced.

About 10 minutes into this video – the trimotor power train is described at the delivery event.

Carbon-wrapped sleeve for the motor and the Tesla Plaid power train.

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. It is the most advanced motor on Earth and increases its torque and max rpm for the Semi, Cybertruck and Plaid Model S/X.

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.

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 (AFP) systems

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%.

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

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.

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.

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.

There are also some limitations to consider when using AFP systems:

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.

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

Carbon fiber composites offer a lighter and stronger alternative to traditional materials, which can lead to improved fuel efficiency, range, and performance.

Tesla’s Plaid motor uses a fiber sleeve to hold the rotor in place.

One motor is constantly engaged and operating at the maximum efficiency point.
Clutched automatically.
Two acceleration units, one highway unit.
Other two units for torque and acceleration.
A tiny motor on one axle. It can be carried in your airport luggage.

Tesla also has a better and more efficient heat pump.

Most of the passenger EVs on the road today run using 400-V batteries. EV buses and trucks are 600-V-class vehicles, and 800 V is starting to be adopted for passenger vehicles.

The introduction of 800-V systems, a significant step up from existing 400-V systems, is happening faster than many predicted. What are the benefits of an 800-V system, and how do they help solve some of the problems that have been barriers to consumers and slowed the rollout of electric vehicles?

How Does an 800-V Battery Impact the Vehicle Design?
The core elements of a brushless dc (BLDC) motor are the rotor that generates a dc magnetic field (typically permanent magnets or a dc armature winding) and the stator that contains copper windings through which ac current is passed.

Motion relies on the interaction of the rotor magnetic field and a rotating magnetic field generated by time-controlled currents in the stator windings. As the motor operating voltage increases for a given input power, it reduces the input RMS current and, therefore, the stator winding copper losses. Losses are typically reduced by a factor of 4 using an 800- versus a 400-V supply.

This offers the opportunity to reduce the copper winding wire diameter, which decreases the overall volume as well as increases the packing efficiency, allowing for smaller motors. The same lower current requirements in an 800-V system reduce not just the motor copper losses, but loss in the entire system wiring loom, introducing weight, space, and cost savings.

Typically, 800-V systems also move from silicon-based IGBTs to silicon-carbide (SiC) MOSFETs. SiC devices provide much higher switching speeds and thus lower switching losses. As a result, the operating frequency will increase, which further reduces motor losses due to reduced harmonic currents.

How does an 800-V architecture help?

Doubling the voltage cuts the current in half for the same power. During charging, heat dissipation is a limitation both for the charging cable and the vehicle charger inlet and internal wiring.

Moving from 400 V to 800 V allows for doubling of the charging rate for the same losses. This has several benefits. The first is straightforward—reduced charging time. If the charging power is doubled, it will take half the time to recharge, though in practice the improvement is less. Not so obvious is the utilization of charging stations. If the dwell time of a charging vehicle is half, then double the number of vehicles can utilize a given charger.

The automotive market has adopted the 800-V architecture faster than was initially anticipated. Porsche led the way, but it’s not just sports cars—Kia and several China manufacturers now offer 800-V vehicles.

8 thoughts on “Tesla Fundamental Engineering Improvements for About 50% More Efficiency Than Competition”

  1. You ignore total vehicle mass, these electric trucks may work around town but doing 500 miles a day with a payload of 22+tonne or much more in Australia means these aren’t going to work. Instead of believing Teslas promos, look at tare and gross weights and distances travelled at 100kmh.

    • Lucid is running out of cash. Their sales are cratering. They sell beyond Model S luxury cars and we are heading into a recession. They lose about $100,000 or more for each car sold. Lucid has maybe $2 billion of cash left and could run out by the end of the year. Saudi investment fund would have to give them more cash, but if sales don’t rapidly accelerate…I do not see how they make it.

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