With lithium-ion batteries, the electric motor is a cornerstone of the electric vehicle.
The household outlet delivers alternating current. This alternating current is transmitted to the battery that stores and converts it into direct current. When running, the battery discharges the current stored to the inverter that changes again the direct current into alternating current (different voltage and frequency) and sends it to the engine.
As soon as the driver takes his foot off the accelerator, the engine becomes a power generator and recharges the battery via the inverter.
For the embedded devices, that are not powered by battery, a transformation is necessary: it is provided by the inverter, which must reduce the voltage of the current.