When growing a brand new electrical powertrain for Formulation E, a number of aims have to be balanced and prioritised. Energy, effectivity and controllability are all essential for producers, and compromise is inevitable when figuring out the perfect total bundle. A extremely environment friendly powertrain is of little use if it can not attain most energy shortly sufficient, has an excessive amount of inertia, or lacks the required software program controls for power administration.
Every of those core parts additionally entails further concerns, highlighting the intensive work required to deliver a challenge from idea to the observe. Since Formulation E started a decade in the past, and powertrain growth was opened up in season two, a number of points of the design and growth course of have matured vastly. We now have extra data and higher instruments than we did again then.
Proof of this may be seen within the inverters, which convert DC present from the battery into AC present for the motor. The inverters at the moment are over 99% environment friendly, and the electrical motors we use are greater than 98% environment friendly. This excessive stage of growth can largely be attributed to enhancements in motor building, electronics precision and pace, and advances in supplies science, leading to elevated {hardware} capability.
When Formulation E first started with a normal powertrain able to 150kW in race mode, we used a five-speed gearbox as we couldn’t obtain most energy early sufficient. My group, Abt Sportsline, lowered this to 3 gears in season two, two gears in season three, and ultimately one gear in season 4.
Eliminating a number of gears was a serious breakthrough within the Gen1 period as gear shifts lead to time loss and harm effectivity. Now, each group makes use of a single gear, which requires particular therapies for the gear tooth. These tooth are made vast and shallow to cut back friction, which improves effectivity and permits the vehicles to speed up seamlessly from 0-300km/h.
Within the first season of Formulation E, groups used five-speed Hewland gearboxes, however when powertrain growth was opened up the main target turned to eliminating a number of gears
Picture by: Mark Sutton
Arguably the most important distinction between previous and current growth lies in advances in software program calculations and predictive engineering. These spectacular developments enable for extra exact simulations of actuality, streamlining the event course of and enabling quicker innovation. As a substitute of manufacturing a number of powertrain iterations and testing them bodily to search out the perfect resolution, a lot of the optimisation can now be completed just about earlier than elements are manufactured.
So, what are the principle standards we search for in a Formulation E powertrain? First, it’s important to realize most energy throughout all revs as early as doable. We’re restricted to 350kW, so the motor should function at its peak with out exceeding that restrict, which might lead to a penalty. Energy management is difficult, significantly when the motor, gearbox and driveshaft oscillate over kerbs or bumps.
A throttle map that delivers torque easily is a key space the place the motive force can affect growth. I concentrate on how the motor behaves underneath braking, how its positioning impacts the automotive’s stability, and optimising software program controls, like how the motor responds to regenerative braking.
A bigger motor with thicker copper wiring sometimes has much less resistance. Nonetheless, a bigger motor additionally means extra mass and weight
Incremental positive factors in effectivity are a steady space of focus. We’re all the time searching for an additional 0.1% or 0.2%. The essential factor is reaching effectivity throughout the whole bundle, not simply within the motor and inverter.
Along with excessive peak effectivity, we purpose for top common effectivity, which requires a big motor. A bigger motor with thicker copper wiring sometimes has much less resistance. Nonetheless, a bigger motor additionally means extra mass and weight, so different elements should even be thought-about. Lightness has clear advantages for effectivity, and low inertia can also be crucial.
Putting the precise stability is a posh job that all the time requires compromises, however the advances remodeled the previous 10 years have been really exceptional.
Di Grassi is now a key cog within the growth of recent Lola/Yamaha Formulation E powertrain that shall be utilized by Abt subsequent season
Picture by: Lola