In order to meet the stringent CO2 targets of the EU and China, the share of electrically powered vehicles in the product spectra of the car manufacturers must increase significantly: While 95 grams CO2 per kilometer driven will still be permitted in 2021, emissions in 2030 will only be allowed to reach a maximum of 59 g per kilometer. According to Stephan von Schuckmann, head of ZF’s Driveline Technology Division, in order to achieve this goal, the share of electrically driven vehicles must multiply in the decade ahead – from currently 4% to 24% of the units produced. In the same period, the share of conventionally driven vehicles will decrease from 90% to 61%.
The problem: Currently 50 % of car buyers can imagine buying an electric vehicle – but less than 2 % actually do, Schuckmann explained in a virtual press event. The reasons are well known: Still too low ranges, too high prices, an all too thin network of charging stations. Changing this will be one of the focal points of ZF’s strategy. The company plans to invest massively in electromobility – and in return gradually phase out its products for conventional combustion engines, explained Michael Ebenhof, Head of Didvision Car Driveline Technology at the supplier. A farewell in installments, but definitely a farewell: ZF does not plan to invest in the further development of technologies for the internal combustion engine anymore; conventional transmissions are also no longer to be developed from scratch – which does not necessarily mean that production will be discontinued in the foreseeable future.
In the 4th generation PHEV transmission currently under development, the weight and installation space of the power electronics are to be reduced by 50 %. Peak power and torque are to be 60 % higher than in the current generation – with the same installation space requirements. An integrated two-speed gearbox is to help achieve the optimum operating point and increase efficiency. “Today, a vehicle manufacturer has to decide between high speed or high starting torque,” explained Ebenhof. “With our new motor, we will resolve this conflict of objectives”.
Future e-motor concepts will have a modular structure, explained Dirk Walliser, responsible for Corporate R&D at ZF. There will be two development lines – 400 volts for volume applications and 800 volts for the premium segment. With this, ZF wants to cover the power range from 80 kW to 200 kW. The introduction of a new generation of power semiconductors is expected to play a key role: In the future, ZF intends to increasingly use SiC (silicon carbide) transistors. “SiC represents a promising option”, says Walliser.
The reason: These transistors enable a higher efficiency than the currently predominant silicon transistors. They could increase the range of electric cars by 5 to 7 % – or reduce costs accordingly by using a smaller battery. In addition, the use of SiC transistors in the inverter should drastically reduce the charging time. “This brings us to around 20 minutes,” explained Walliser. “That’s in the range of the time one spends today at a normal motorway service station”. In the development of high-voltage inverters, ZF is cooperating with Danish company Danfoss, which in turn purchases its SiC semiconductors from Cree.
This article is part 1 of a two-part report on ZF’s virtual press event. The second part, to be published soon, will deal with digitization challenges in the automotive market and ZF’s strategy in this field.
Image material © ZF Friedrichshafen AG