ZF develops new Range Extender EV system

While the switch to fully electric vehicles is still subject to charging infrastructure readiness and consumer confidence with regards to range, development of hybrid electric vehicles (HEVs) is proceeding briskly. This approach offer a lower cost to manufacturers and consumers and eliminates the issue of range anxiety as the battery is self-charging.

While HEV technologies all use both a combustion engine and an electric motor, there are different layouts and one of them is the range extender approach. This has a small combustion which is used only to recharge the battery and not to power the vehicle itself. Only the electric motor powers the vehicle, just like a fully electric vehicle.

Range Extender Electric Vehicle (REEV) technology has been around for over a decade and besides proprietary systems such as Nissan’s e-POWER, ZF has also been developing REEV systems that manufacturers can use.

New generation
It recently announced a new generation of this technology which will go into volume production in 2026. Designed to meet increasing global demand, this further development is ideally suited to meet dynamic market and customer requirements as well as flexible drive concepts.

The next generation is referred to as electric Range Extender (eRE) and electric Range Extender plus (eRE+). Both variants are highly integrated designs that are flexible in terms of performance, E/E architecture, 400V or 800V and semiconductor type.

The eRE connects an electric motor with an integrated inverter, suitable software and planetary gearset. The eRE+ also has an intelligent clutch and a differential. As a result, it can be used either as a current generator or as an additional secondary drive which saves manufacturers developing a separate component.

Performance can be scaled for both models. The output ranges from 70 to 110 kW (eRE) or 70 to 150 kW (eRE+). “The new interest and the increased demand for range extenders shows that the potential of this technology is far from exhausted – in particular for model platforms that are already designed for battery-electric drivelines,” said Dr. Otmar Scharrer, Senior Vice-President R&D, ZF Electrified Powertrain Technology.

Advantages for manufacturers and customers
Compared to parallel-hybrid drive solutions (eg a PHEV), REEVs are compelling due to their lower additional costs, shorter development cycles, reduced platform integration effort and simplified supply chain management. This makes the technology particularly interesting for manufacturers who are new to the market and may have little experience with traditional combustion engine drivelines.

China is currently embarking on a REEV model offensive which, thanks to the technology, can cover distances of more than 700 kms. “This is where we find it convenient that there is a wide range of fully electric platforms that can be supplemented by range extenders,” explained Scharrer, adding that ZF units in China have led the development work.

However, the interest of manufacturers is also increasing in the USA and Europe. “The market for fully electric vehicles has not developed as much as predicted a few years ago,” said Scharrer. “For this intermediate phase, range extenders can be the ideal solution.”

REEV drivers can enjoy the advantages of electromobility without having to sacrifice the flexibility of PHEVs or combustion engine cars. Range extenders are also of interest for traditional manufacturers. They allow smaller (and therefore more economical) vehicle batteries to be installed and help to comply with emission limit values for fleets.

Hyundai Motor Group develops new hybrid electric system