Lucid Motors calls its engine design miniature, and it has long boasted that the light and “unimaginably compact” engines in its Air electric sedan are thin enough to fit in an airplane bring.
However, lean and small is only one aspect. Lucid’s engines weigh just 67 pounds each and are capable of making 670 horsepower—yes, that’s 10 horsepower per pound.
2022 Lucid Air
Furthermore, Lucid’s silicon carbide inverter, reducer and differential, packaged together, weigh about 163 pounds.
It’s very, very dense with power. And in a tech talk released by the company on Tuesday, Lucid CEO and CTO Peter Rawlinson and Powertrain Manager Emad Dlala presented the priorities that engines are designed around. around, as well as insulation and efficiency, through low resistance and thermal management, were part of the plan from the start — along with ease of production.
You’ll want to watch the entire presentation — over an hour — for the internal physics lesson, and you’re bound to learn a lot not only about this unit but about the engine in general. But these four slides, comparing Lucid’s engines with those of Tesla and Porsche, get to the gist of it.
The apparent weight of the stator and rotor vs
Flexible engine weight vs
Flexible energy density compared
Compare flexible power and engine weight
Rawlinson notes that the project involves going back to physics and looking at the entire powertrain as a single overall inertial system.
The two spent a lot of time discussing the design of the stator – the static outer part of the motor, with current being shaped by the inverter, creating a magnetic field that rotates the rotor in the middle.
For example, the stator for Lucid’s six-pole permanent-magnet synchronous motor does not use copper windings like many such motors, and it also does not use a hairpin. Instead, to reduce power loss plus easy assembly, Lucid sought a coil assembly that continuously wound the stator with a limited number of solder joints. It is made with a CNC controlled machine and a process similar to weaving. A CNC controlled mandrel then aligns and inserts the weave.
Carbon wrap on Tesla Model S Plaid engine
The pair even made some fun of the workaround Tesla used in its engine for the Plaid — a carbon fiber shell that Rawlinson notes is the same kind of technology used in the process. hydrogen storage for fuel cells, to keep extreme pressure. Dlala speculates that scaling that to large volumes will be costly.
Lucid also cools its engine differently than a Tesla, Porsche or any other design we know of. Lucid’s strategy is to extract whatever heat it can super close to the slits instead of waiting until the heat is radiating outside. A center channel in the stator functions as a manifold, running the ATF (automatic transmission fluid) through narrow channels, helping to separate heat through that grid.
The busbars connecting the motor to the inverter are also as short as possible, to reduce resistance (and therefore heat). That is an advantage of the motor as it is designed in a single unit with inverter.
Lucid’s Rawlinson and Dlala . Presentation Drives
The bottom line: Lucid emphasizes that its drive units are light, compact, efficient, power-efficient, and scalable.
Although Lucid doesn’t really give an efficiency analysis of the motor unit versus the magnetic unit Taycan and Pattern S Plaidit implies based on the entire presentation that its motivation also contributes greatly to efficiency.
On that point, Rawlinson ventures that the motor itself weighs so little – only 11% of the overall mass of the battery pack – that if they can get the performance out of the unit’s design then about it is basically a “zero mass drive unit”.