An electrically assisted turbocharger (EAT) is an arrangement where an electric motor assists the gas-driven turbocharger in providing forced induction, particular at times when exhaust gas flow is insufficient to produce the desired boost.[1] Some systems integrate the motor inside a turbocharger, while others use a separate electric supercharger.
Systems
BorgWarner
BorgWarner tested the idea in the 1990s, but never produced a part for production vehicles because of high power consumption, until the Mercedes-Benz M256 engine (2017), which used a 48-volt electrical system.[2]
As of January 2023[update], BorgWarner markets two EAT solutions: a standalone "electric compressor" (i.e. supercharger) named eBooster and a turbocharger with a single-shaft motor attached named eTurbo.[3]
Garrett Motion
In October 2019, Garrett Motion announced its first electric turbocharger for market passenger vehicles, with expected launch in 2021.[4] The design adds an electric motor between the turbocharger's turbine wheel and compressor wheel.
The 2023 Mercedes-AMG SL 43 convertible uses the Mercedes-Benz M139 engine, which features the integrated Garrett Motion EAT.[5]
Volkswagen TDI
The TDI line used by the Audi brand has seen 4.0 V8 TDI 310-320kW, used on the Audi SQ7 and more. It has 2 turbochargers and 1 electric supercharger.[6]
Volvo
In 2010, Volvo started to experiment with electrically assisted turbochargers. The result was unveiled in 2014, a 450hp 2.0L High Performance Drive-E Powertrain Concept engine, which used a 48-volt electrical system for the electric booster. The engine has three turbos, with the electric "turbo" driving the exhaust turbines of the twin-turbo.[7] Despite initial reports that the Volvo XC90 T6 would have a related improvement,[8] only the 2016 Volvo XC90 T8 actually received a Twin Engine starter-generator-supercharger in addition to the mechanical twincharger arrangement.[9]
In 2019, Volvo reiterated plans to replace the mechanical supercharger with an electric one.[10]
Abandoned
In the late 1990s, Turbodyne also investigated EAT designs.[11]
Related devices
An electric supercharger also uses an electric motor to power the compressor, however the electric motor is the sole power source in an electric supercharger.
A turbocharger that can divert some of the exhaust gas to produce electricity (using the vehicle's alternator) is sometimes called a hybrid turbocharger.[12]