How does an electric motor drive the wheels?
The car pulls away from the driveway without a gear change and almost without a sound. Only a soft hum is audible outside.
At the first junction it accelerates smoothly from standstill, with full pull from the first metre.
The questionWhat happens between the battery and the wheels, and where does the hum come from?
The traction battery delivers direct current at several hundred volts. A small DC/DC converter also feeds the 12-volt system for lights and electronics.
Select each part to see what it does.
Few parts, little loss
The path from battery to wheel has few parts, and each converts energy with little loss. According to the US Department of Energy and EPA, electric cars convert over 77% of the electrical energy from the grid into power at the wheels.
The core components are the same in almost every electric car: traction battery, , electric motor, a simple transmission, plus an and a thermal system.
Magnets or coils
Most electric cars today use a synchronous motor whose rotor carries permanent magnets, usually made with rare earth elements. There are alternatives without them:
- Induction motors use only electromagnets and need no rare earths.
- Synchronous motors with coils on the rotor create the magnetic field electrically instead of with magnets.
Some cars combine two motor types, one on each axle, each used where it works best.
A sound by law
Because an electric drive is so quiet at low speed, the EU requires an acoustic vehicle alerting system, . It must generate a sound from start up to about 20 km/h and when reversing, so that pedestrians, especially blind and visually impaired people, notice the car. AVAS has been mandatory for all new hybrid and electric cars since 1 July 2021.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
What does the inverter do?
Converting AC from the grid is the onboard charger's job, and watching the cells is the BMS's. The inverter feeds the motor.
Why do most electric cars need no gear changes?
A single reduction gear is enough. The motor's wide speed range does the work a gearbox does for an engine.
Why must new electric cars in the EU make a sound at low speed?
AVAS compensates for the missing engine sound up to about 20 km/h and when reversing.
- AVAS Acoustic vehicle alerting system: the sound EU law requires from electric and hybrid cars up to about 20 km/h and when reversing. Glossary
- Onboard charger The converter in the car that turns AC from a wallbox or public AC charger into DC for the battery; its rating limits AC charging power. Stop 04 Glossary
- Power electronics Semiconductor circuits that convert and control electrical energy: in the car mainly the inverter for the motor, in a DC charger the rectifier and the DC/DC converter. Glossary
- U.S. Department of Energy and EPA, fueleconomy.gov: All-electric vehicles. https://www.fueleconomy.gov/feg/evtech.shtml. Checked 09 Oct 2026.
- U.S. Department of Energy, Alternative Fuels Data Center: How do all-electric cars work?. https://afdc.energy.gov/vehicles/how-do-all-electric-cars-work. Checked 09 Oct 2026.
- IEEE Spectrum: How to build EV motors without rare earth elements (Rallabandi, Ozpineci, Kumar, 2 July 2024). https://spectrum.ieee.org/ev-motor. Checked 09 Oct 2026.
- EUR-Lex: Regulation (EU) No 540/2014 on the sound level of motor vehicles, Article 8 and Annex VIII (AVAS). https://eur-lex.europa.eu/eli/reg/2014/540/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.