Bundled, crossed, mixed: With hybrid drive in the car, combustion engines and electric motors do things together. The goal: more efficiency. But there are big differences between the variants.
Stuttgart (dpa / tmn) - Cars with hybrid technology have one thing in common: No matter how the drive is designed - it should make driving more efficient, the vehicle more economical and lower emissions. But the similarities end there.
Basically, a distinction can be made between basic system architecture structures. So it's about how the internal combustion engine, electric machine, generator, battery and gearbox are arranged and connected to each other, says Andreas Richter from the Competence Center for Electromobility at the expert organization Dekra.
Accordingly, one speaks of serial, parallel or power split hybrid drives. If you order the systems according to the degree of their hybridization, one speaks, for example, of mild hybrid, full hybrid or plug-in hybrid.
The mild hybrid - rarely electrically alone
Here the e-machine supports the combustion engine and has a performance-enhancing effect. The electric motor helps especially when starting and overtaking. So whenever the internal combustion engine has to build up torque, which is available electrically ad hoc. As with all hybrid systems, the guiding idea is to let the combustion engine run as close as possible to its optimal, i.e. most efficient, operating point, says Richter.
"Overall, the savings potential is manageable," says Matthias Vogt, specialist for electromobility at the ADAC Technik Zentrum in Landsberg. Depending on the driving situation, the petrol engine and electric motor work in addition, in phases the electric motor charges the battery when necessary. Because both motors can operate at the same time, the mild hybrid is one of the parallel hybrids.
With the emerging 48 volt technology, four times as much power can be used with the same current compared to conventional 12 volt. For example, 48-volt mild hybrids can swim, park, or maneuver in traffic using purely electrical means. "However, full-fledged driving tasks cannot be performed," says Richter.
The full hybrid - sometimes so, sometimes so
The drive system is similar to the mild version, only the electric motor is more powerful and the on-board voltage is higher, according to Richter. Purely electric, conventional and combined driving is possible. When it comes to saving fuel, the full hybrid is particularly worthwhile in city traffic. But the battery is quite small and the range is limited to a few kilometers.
The best-known example of this design is the Toyota Prius, which has been built since 1997. According to ADAC, its technology is designed to improve performance and efficiency at the same time by automatically selecting the optimal operating mode. On the way, both engines act together and act on one gear.
From a system architecture perspective, the Prius and other full hybrids such as the Hyundai Ioniq or the Kia Niro could also be called mixed hybrids because, depending on the driving condition, they also work in series - the combustion engine charges the battery and the vehicle can run purely electrically. The principle is also called power split because it has the characteristics of a serial and a parallel hybrid.
Range Extender - More range
The serial hybrid vehicles, in which the motors are not connected in parallel, but in series (series), also include those with a range extender. "The direct drive is usually only via the electric motor," says Matthias Vogt from ADAC. The combustion engine, often a small three-cylinder, works in the background as a small electric power plant. Because its job is to drive a generator that recharges the traction battery as soon as it is empty. This means that the vehicle does not have to be plugged in immediately.
As a rule, the range extender does not act on the crankshaft and is therefore decoupled from the drive. This means that it always runs in a fuel-saving manner in the optimal speed range. In addition to the temporarily available BMW i3, the Fisker Karma or the first Opel Ampera from 2012 are among the range extender models - but in some driving situations the Ampera's combustion engine can directly participate in the drive.
Because there is a lot of loss in the exchange of energy between fuel, generator, battery and electric machine, range extender models do not have the greatest savings potential. "They are best used as a remedy for fear of the range," says Dekra expert Richter.
Plug-in hybrid - with socket
Hybrid vehicles that can be charged from the outside are called plug-in hybrids. "They have a significantly stronger electric motor and a larger high-voltage battery than full hybrids," says Vogt, ADAC specialist. Purely electrically, they are faster, around 100 km / h are possible. The additional battery size allows distances between 30 and 60 kilometers, the recuperation performance is also higher. In cities you can drive them locally emission-free.
According to ADAC, plug-in hybrids are particularly suitable for commuters if they can be recharged at starting and destination locations. "For a company car that is driven over long distances on the motorway, the plug-in hybrid is not the best option from an environmental point of view," says Vogt.
They are also suitable as a remedy for fear of range, the gas tank is usually large. Vacation trips are not a problem. However, long-distance use should be the exception for the highest possible electrical driving share in everyday life. The consumption advantages are otherwise quickly consumed, and the CO2 emissions increase quickly when the battery is empty to or even above the level of a pure combustion engine.
