Most electric cars aren’t normally associated with performance, but they are able to achieve something gasoline-powered cars can’t: peak torque at zero rpm.
It’s thrown around often, and many will comment on how quick an electric car feels around town thanks to maximum torque delivered instantly. If in doubt, just take a ride in a Tesla Model S and ask the driver to drop the hammer.
But how does an electric car achieve this? Jason Fenske from Engineering Explained is back to make sense of the gadgetry going on. Foremost, it’s important to realize there isn’t an engine under the hood of an electric car. Instead, there is a motor, generator, and a battery pack to supply power. As the electric current travels through the motor within a magnetic field, it generates a force. The more current applied, the more the motor will spin.
A generator is doing a similar thing, but its spinning motion is occurring in the opposite direction simultaneously with the motor. This creates what’s called “back electromotive force” or “back EMF.” The faster the motor spins, the more back EMF is created. Thus, there is an equilibrium at zero rpm and all of the power created becomes instant torque. The higher the revs, the more back EMF and the instantaneous torque effect diminishes.
It’s this effect that gives a rather mundane, let’s say, for example, Chevrolet Bolt EV the power to scoot away pretty quickly from a stoplight. It’s not jaw-dropping amounts of torque, but the maximum output on tap from zero rpm does create a more entertaining drive. Grab all of the knowledge surrounding electric motors in the video above.