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New cheap hybrid drive
Research teams at TU Darmstadt, together with industrial partners, are developing a cost-effective drive for hybrid vehicles that consists of two electric motors and a natural gas engine.
New cheap hybrid drive
The idea behind the DE4LoRa (double electric drive for long range) project: In the future, low-emission vehicles should not only be suitable for everyday use, but also affordable. “For many users whose daily journeys rarely exceed 100 kilometers, high-voltage hybrids are a sustainable solution,” says Stephan Rinderknecht, an expert in mechatronic systems in mechanical engineering at the TU Darmstadt and one of the initiators of DE4LoRa. “We are currently developing and testing the technical basis in the form of a new reference architecture.”
Hybrid, rethought
High-voltage hybrids such as the popular plug-in hybrids are relatively expensive, as is the alternative of purely battery-electric drive. DE4LoRa is intended to make the drive more cost-effective and at the same time reduce the overall ecological footprint. Two 800 volt electric motors and a natural gas engine are connected via a special transmission concept. A bidirectional charging system was developed for the charging process, which reduces charging losses to a minimum. There is no need for a bulky transformer in the vehicle without compromising electrical safety. The two identical electric machines are used to high capacity because they work more efficiently than a single larger electric motor. Depending on the load requirements and speed, DE4LoRa uses either only one electric motor for lower performance, or both with a total of four different gear ratios. Conclusion: The majority of everyday journeys are possible purely electrically with a moderate battery capacity. Since the combustion engine has four parallel gears and can be switched on in series, the concept is suitable for long distances despite the comparatively low battery capacity.
Optimized natural gas engine
The natural gas engine is operated with compressed natural gas (CNG) and is characterized by significantly lower greenhouse gas emissions compared to a gasoline engine. It is also more efficient than a dual-fuel CNG engine, which can run on both natural gas and gasoline. Through intelligent use of the two electric machines, the DE4LoRa gas engine does not have to follow all dynamic changes and can therefore run more often in highly efficient and low-emission operating areas - in so-called "phlegmatized" operation. This saves further fuel, enables a less complex structure and smaller dimensions, which reduces costs. This creates a new, coherent overall concept with maximum efficiency that is both ecologically and economically attractive and is also recommended for use in smaller vehicle segments.