Traditional gasoline vehicles must be equipped with a gearbox to drive normally, so as to be suitable for driving at various speeds and maintain fuel economy and power output. However, new energy-electric vehicles do not have gearboxes. Strictly speaking, electric vehicles also have gearboxes.
Are Electric Vehicle Transmissions Necessary?
After a hundred years of history of traditional fuel vehicles, people are used to the logic of shifting gears when driving. It is absolutely necessary to combine a multi-speed transmission with an internal combustion engine. In EVs, perhaps people conclude that multi-speed transmissions are a given, but none of them are. Do EV transmissions need improved performance?
Electric motors develop their maximum torque at very low speeds, DC motors produce their maximum torque near (zero rpm), and AC motors typically produce their maximum torque around 1000 rpm. As revs increase, torque drops off at a fairly linear rate, while power also increases. For example, according to ORNL (Oak Ridge National Laboratory) testing on a 2004 Toyota Prius, the motor produces up to 500 N•m of torque at around 3001 rpm and drops to around 50 N•m at 6000 rpm. At the highest efficiency, 100 N·m of torque can be obtained at 2250rpm, which is very suitable for cruising. In any case, a multi-speed EV transmission is unnecessary, since even 100 N·m at cruising speeds, this torque is sufficient.
Of course, that doesn’t mean EVs can’t have gearboxes, but they aren’t required. First of all, considering the torque/power/speed characteristics of the motor, most working conditions can be met without adding a gearbox. Second, multi-speed EV transmissions add weight, complexity, friction, and inefficiency to an otherwise simple structure, effectively robbing the powertrain of torque, power, and efficiency.