The electric biturbo is a completely new technology developed by Audi. In it, the turbocharger works together with an additional electrically powered compressor. Instead of the turbine wheel, it has a small built-in electric motor which accelerates the compressor wheel rapidly to very high speeds.
The electric turbocharger is arranged downstream of the charge air cooler; in most operating states it is bypassed. If the exhaust gas has little energy at very low engine speeds, the bypass valve closes and the electric turbocharger is activated. The new technology enables previously unachieved levels of spontaneous power build-up when driving off and at low revs.