I’ve never seen an ICE car need two engines to drive all four wheels. Why do EVs need 2 motors? Wouldn’t a transmission be cheaper than another motor?
I’ve never seen an ICE car need two engines to drive all four wheels. Why do EVs need 2 motors? Wouldn’t a transmission be cheaper than another motor?
A virtual locker doesn’t work as well as a physical locker offroad because there’s no leverage limiting wheelslip. In a mechanical locker you only get wheelspin when grip is low enough for both wheels to spin, while a virtual locker will get wheelspin when the grip of one tire is surpassed. Per-wheel motors lack this leverage too, making them not as good as a physical locker. A system with mechanical lockers on both axles with a locked center-differential does even better because you’ll only get wheelspin if all four wheels lose traction.
This just isn’t true.
Let’s imagine a scenario where you have 0% traction on one wheel, 5% on a different wheel, 30% on one wheel and 60% on the final one.
A lockout would basically add torque evenly, which doesn’t necessarily help, especially in dynamic situations (not a “stuck in the mud” but a “driving in the mud” scenario).
A car with dynamic 4-motor drive could do microsecond-resolution changes to torque to prevent any wheel from ever slipping. It’s rather amazing how much better than a traditional locking diff this would be.
There is absolutely zero reason you couldn’t program a 4-wheel electric setup to behave exactly like a locked diff. Electric motors are flexible and can add torque and direction in any amount at any time, but you probably wouldn’t ever do that because it’s not as good.