Tomorrow’s powertrains – more efficient, more powerful, more complicated?

Powertrain electrification has given innovation an enormous boost – and the desire and need to further reduce CO2 emissions will accelerate that development in future. As a result, we can expect ongoing improvements to existing solutions and the development of innovative new concepts.

CTI symposia – an eye for essentials
The architectures of electrified powertrains, with their subsystems and components, have become more complex. Various hybrid drive versions now compete, and powertrains use multiple motors in different roles. All-electric drives are also highly diverse, with new options being added all the time. This obscures the path forward, and drives up development costs.

Sophisticated drive design – from battery stack to in-wheel motor
CTI SYMPOSIUM Germany will show how intelligent strategies can master this growing complexity, and how the most promising solutions can be filtered out systematically from the wealth of possibilities. It will also make clear that in order to optimise powertrains, developers need to think even more holistically – a process that now involves focussing more strongly on energy storage systems.

New Energy runs in the family – developing a flexible transmission concept
The future belongs to powertrains with different levels of electrification. This means vehicle fleets urgently require multiple new energy solutions. One thing the different approaches have in common is the growing complexity of their powertrain structures. In response to these challenges, GETEC has designed a new energy product family that will be presented at CTI SYMPOSIUM Germany by Sven Steinwascher (GETEC, Germany).

The transmission concept is designed for use in EV, REEV (Range Extender EV) and DHT applications. The development goal was to use as many common parts as possible for subsystems and components, in order to reduce costs and development times for each product in the family. The outcome of the concept study was a two-speed power shiftable gear train as the base for the various applications. For EVs, the gear train will be equipped with an EM on the input side. For REEVs, an additional e-motor will be added that is directly connected to the ICE (P1 type) to also permit series hybrid mode. For DHTs, the REEV application will also be fitted with a separation clutch to allow a direct mechanical gear from the ICE to the wheels. This will enable full hybrid functionality including boost mode, load point adaption, series and parallel hybrid mode. This flexibility will enable OEMs and Tier 1 suppliers to respond quickly to dynamic market challenges. As part of his presentation, Sven Steinwascher will also summarise the development conditions of complex powertrain systems under high market pressure.

Dedicated hybrid powertrains – high-level optimisation
When it comes to achieving short- and medium term CO2 targets, dedicated hybrid powertrains (DHP) provide a good cost-efficiency ratio. At this level of hybridisation, powertrains comprise an ICE and an e-motor with a Dedicated Hybrid Transmission (DHT). “DHPs have been optimised over several generations for high efficiency and low complexity,” says Dr Wolfgang Wenzel (BorgWarner, Germany) in his lecture. “The goals were to improve fuel economy and reduce the high cost of the electrical components.“

Cost-wise, DHPs are attractive because they combine electric motors with simplified transmissions and combustion engines. They boost efficiency by keeping the ICE running in the sweet spot, and by recuperating energy. In a simulation study, Dr Wolfgang Wenzel compared the design requirements, CO2 potential and performance of various dedicated HEV hybrid powertrains for a C-segment vehicle. The study compared two well-known concepts – power split and multi-mode DHT – with a 4-gear DHT and a parallel P2 architecture with DCT, which served as the benchmark. The hybrid controller used the Equivalent Consumption Minimizing Strategy (ECMS). Key aspects of the study include optimising transmission designs for use cases by incorporating driving requirements, identifying individual influences and their effect on the system, and a discussion of the advantages and disadvantages of each main approach. DHPs have great potential for further development; in his lecture, Dr Wolfgang Wenzel will illustrate some of these opportunities.

More compact, more efficient – battery and e-axle as an optimised overall system
Like drives, energy storage systems play a prominent role in electric vehicles. In the early days, issues like range anxiety and charging times tended to dominate the discussion. Today, developers are factoring battery / e-axle interaction into their powertrain designs. A new joint venture by the Chinese Evergrande Group and German engineering specialist Hofer Powertrain aims to develop the optimal battery / e-axle combination for different individual overall systems. In his lecture, Hartmut Schneeweiss (Evergrande hofer Powertrain, Germany) will present the results of a simulation process that examined the interaction between EMs with an optimised transmission unit and new energy storage strategies.

The process focus rested on improving the electric axle in ways that would also permit the energy storage system to be downsized in terms of size, power and weight. There were three main objectives: to operate the e-axle in the ’sweet spot’ more frequently; to reduce material and power consumption for the e-axle drive, and to reduce battery volume and weight via a new, multifunctional design. This involved downsizing all electrical components while improving the vehicle’s overall energy balance. In an iterative simulation process, the best component combinations (e-axle / battery) were identified and evaluated with incremental improvement. Function blocks were defined, and their potential continuously re-tested. Within these function blocks, developers could alter factors such as new battery cell technology, SuperCaps, new semiconductor materials and different e-machine types as desired. Finally, a product specification for a new e-axle and a recommendation for an energy storage system were created.

In-wheel motors – making space for innovative solutions
Unlike e-axles, which are based on a classic drive model, in-wheel motors use a fundamentally different concept. Obvious benefits include independent torque control at each wheel for greater safety and manoeuvrability, and weight and energy savings achieved by removing unnecessary components such as transmissions and power transmission components.

In his lecture, Richard Burke (Protean Electric, Great Britain) will take these qualities as a given and will address a different aspect that may prove more decisive in future: namely, the fact that in-wheel motors are extremely compact and require no extra space in the chassis. To specifically assess the potential benefits, Protean has modelled the chassis structure and interior spaces of a range of EVs. Options under consideration include modifying the wheelbase, and packaging the battery in the space gained. Unlike e-axles, which tend to constrain passenger car design options, in-wheel motors could afford designers a new level of freedom in future.

Electric Vehicles – meet your new buyers!
In 2009, people who owned a Tesla Roadster felt like pioneers. Eleven years on, electric vehicles are established in the market, with dozens of new models planned to arrive the next few years. These next-generation vehicles are encountering a new generation of buyers.

In his analysis, Mike Dovorany (Escalent, USA) will focus on customers and speak of a ‘tipping point’ brought about by the fact that newly developed electric vehicles differ significantly from their predecessors in terms of performance (longer range and shorter charging times), design and functionality. “As a result, they are already attracting very different buyers than EVs in the last decade.” In an informative comparison with first-generation buyers (2009 – 2019), Mike Dovorany will detail the specific characteristics of this new generation. Taking market-specific differences between Europe, China and the USA into account, he will present the latest research results and address common misunderstandings. As his lecture will show, it’s not just automobiles that change over time – buyers and drivers do too.

CTI SYMPOSIUM Germany goes online – and boosts its energy density
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