A new range-extender powertrain that uses patents-pending NVH reduction technology will be tested in a subcompact plug-in EV later this year.
"Our range extender is an additional option for electric cars. That is why we have an easy mounting concept that requires only a few connections, including one single cooling circuit for the internal-combustion engine (ICE), generators, and the inverter," Dr. Hans-Joachim Esch, Chief Technical Officer for KSPG (formerly Kolbenschmidt Pierburg), told AEI.
KSPG and the engineering services company FEV are co-developing the range extender. In its demonstration configuration, the power unit features a 0.8-L V-twin gasoline engine that is packaged horizontally, so that its crankshaft is positioned vertically. The ICE is combined with two 15-kW permanent-magnet synchronous motor (PMSM) generators.
FEV technical specialists converted a Fiat 500 to battery-electric power as a demonstrator platform for the range extender. The complete 30-kW range extender weighs 60 kg (132 lb) and is packaged in the car's spare tire well.
"In order to keep the range extender simple and cost-effective, we chose a serial hybrid design with two generators that supply electric energy for the battery, or for the electric drive," said Dr. Esch. "There is no mechanical connection between the range extender and the wheels."
FEVcom vs. NVH
A distinguishing feature of the range extender is its NVH signature, especially during the ICE's stop/start events.
"If you are driving a battery-electric vehicle, it is really quiet. The range extender also needs superior NVH characteristics," said Dr. Esch.
To address unwanted NVH, the FEV-invented Full Engine Vibration Compensator (FEVcom) has a pivotal role. According to Dr. Martin Pischinger, Vice President of Electronics and Controls at FEV Inc., the main feature of the FEVcom is its active vibration compensation design.
FEVcom's unit has two shafts that are used as the rotors of the two generators in the range extender. In simple terms, the two PMSM generators are connected via a FEVcom gear drive to the engine crankshaft, explained Pischinger.
As part of the development process, FEV has conducted in-house NVH tests on its FEVcom technology using a single-cylinder, four-stroke, spark-ignition engine.
The range extender is KSPG's first major electric mobility product. According to Dr. Esch, the main focus of the company's product development is "to further improve the technology of combustion engines with a view to emissions reduction, lower fuel consumption, and performance. But we realize a change is coming in propulsion technology, and we certainly want to contribute to these new developments and markets."
The first battery-electric subcompact car fitted with the KSPG compact range extender will debut as a technology demonstrator sometime in the summer.
"One thing that we have learned since we have been working in this field of electro-mobility is that you need to come up with ideas and you need to demonstrate those technologies," Dr. Esch said.