February 26, 2021

Step by step electrification - a paradigm shift in the powertrain

Step by step electrification - a paradigm shift in the powertrain

The second part of our article on electrification features hofer powertrain expert Volker HARTMANN talking about possible approaches to powertrain electrification. He sets the ground for the topic-specific insights that await you in the coming weeks. In addition, our engineering teams provide tips on preparing for the transformation that is already underway. Other topics include the possible changes, deriving market consequences and thought-provoking ideas for the future vehicle development.

The number of vehicle manufacturers focusing their attention exclusively on fully electric concepts is limited. Some innovation-driven carmakers like Tesla stormed the market with the first wave of electrification and put purely electric vehicles on the production line well ahead of the competition. However, most vehicle manufacturers have chosen an alternative development path - moving step by step from combustion engines to CO2-reduced drive solutions. Conventional vehicles with 100% combustion engine drive systems are transforming from a micro, to mild and macro hybrid to a full electric vehicle in order to complete the electrification transition in the future as electrification progresses and electric drive power and capabilities increase. The transition from the combustion engine and a semi-electric design to zero-CO2 fleets requires a high level of innovation, as the variety of solutions is nearly unlimited, while the complexity of the requirements of the overall system is continuously expanding.

Varieties and forms of electrification

The evolutionary leap towards electric solutions in propulsion occurs at the crossing point between plug-in and range-extended EVs.

Electrification has many facets and shapes and the process often involves more than one approach. From plug-in hybrids to range-extended electric vehicles to pure electric vehicle applications, this current evolution process can be accomplished in a variety of ways. The evolutionary leap towards electric solutions in propulsion occurs at the crossing point between plug-in and range-extended EVs. Here, the main power providing element changes from internal combustion engine to electric drive. A large number of automakers and their new models are already moving above this threshold - in the field of e-mobility. Since two propulsion worlds meet precisely at this point, car manufacturers are confronted with the challenge of finding a symbiotic fusion of the two areas to ensure ongoing competitiveness, while maintaining a determined course toward efficiency and sustainability in mobility. A strong focus is given to the installation space requirements and dependencies, as well as the interfaces between mechanical and electrical components and their functionalities.

According to the core needs of the individual vehicle-projects, different technological drivers are visible. In the case of hybrid solutions, those tech-drivers are integrability and torque density; in the case of purely electric vehicles, it is rather a steady performance and an overall powertrain efficiency. Depending on the starting point that guides the development of the drivetrain there are consequently some technological overlaps between the different solutions in these 2 worlds. To progress towards electrification obstacle-free, in a cost- and time-efficient manner, it requires established expertise in both fields - combustion and electric propulsion system design.

What are the crucial criteria when choosing a drive solution, and how does a vehicle manufacturer determine the most suitable type of powertrain for his application?

As demand grows, a large number of electric drives and drive variants are entering the market. The choice of an optimal solution is determined based on a function-specific and application-specific assessment, depending on the electrification goal. In addition to many years of cross-field experience in different engineering areas, development teams must also have strong expertise at individual components and overall system levels to optimally translate customers´ requirements into reality and provide the most efficient design. An established requirement management process ensures high level of understanding, continuous controlling and early reactions in the design process. Depending on the overall need and the expected outcome, there is a large set of guiding criteria that must be precisely defined and prioritized beforehand:

·      Definition of future driving and handling characteristics and exact parameters for optimization of vehicle dynamics

·      Degree of customization and adaptability of functions and individual components

·      Suitability of the concept for small or large-scale production

·      Definition of a minimum and maximum manufacturing effort as well as the complexity during installation and assembly

·      Definition of optimum compactness of the chassis design and evaluation available installation space

·      The degree of connectivity, the scope of integration of software and possibility of updating to future technologies

·      Relevance and depth of integration of specific safety systems and functions that enable autonomous driving, according to safety regulations

·      Layouts and capabilities for longer commuting distances, including the maximum driving range and short recharging times versus vehicle configuration optimized for urban driving and short commuting distances

·      Possibility of emission-free driving, with e-drive, only playing the role of an e-booster in specific situations and limited durations, e.g. up to 30-50 km, allowing the vehicle to enter green zones in city centers and many more

Depending on the requirements and specifications, engineering experts have plenty of room for variations and innovations in system design, maximizing the outcomes for their customers. There are nearly no limits to the configuration possibilities of the drive solutions.As a result, even more interdependencies occur during the electrification process. These interdependencies and physical effects on the powertrain during the ride have to be defined and managed in a meaningful manner from the start and throughout the design projects, to reduce surprises and implementation times in later realization stages.

More options are presented when deciding on the ideal motor type, the number of e-machines and the right positioning. For example, there are two popular types of e-motors, a synchronous machine (PSM) and an asynchronous machine (ASM). In a synchronous machine with permanent magnets, the magnetic field follows the circulating magnetic field in the stator, running synchronously at a stable speed. This design of an e-machine enables high rotational frequency and is suitable for applications requiring high power density and higher efficiency levels. On the other hand, there are asynchronous machines, which offer significant advantages in terms of initial investment and provide an attractive solution for applications with fewer power requirements. 

Foresightful planning and an end-to-end system mentality ensure stable development and specification processes for maintaining quality and competitive advantages as high as possible. In addition to many experienced experts, established and proven operation methods, highly accurate testing, simulation and analysis processes are essential to achieve success.

 

Flexibility combined with high development speeds and the need for scalability

Requirements for stable quality at high production volumes as well as modularization and scalability add to the complexity of production projects. In order to provide the most effective powertrain solution, engineers must not only choose the right powertrain concept but also consider the application-specific requirements and cross-component issues such as noise and vibration (NVH), electromagnetic compatibility (EMC) and functional safety at a very early stage in the product development process. One of the reasons for this is to provide a stable basis for the following series development. Along with the ever-shorter time-to-market, high availability rates coupled with increasing cost pressure while maintaining at least the same level of quality, the demands on powertrain electrification products are increasing and thus accelerating the pace of change in the industry. But manufacturers often do not have sufficient in-house capacities to easily bring high levels of flexibility, innovation and scalability in all their projects. To ensure their market competitiveness, they need reliable, efficiency-driven partners and system suppliers to assist them and provide holistic support and advice at a system level, regardless of the powertrain type. 

hofer powertain production site in Solihull, UK

 

The ability to handle small series, as well as high-volume production on demand is crucial for many customers. In order to transform visions into real projects and final street-ready models beyond mere concepts, industrialization expertise is key. This expertise includes the appropriate manufacturing and assembly techniques and supplier management. A well-executed industrialization enables safe navigation through all development phases – to SOP and beyond.  

In the next part of Electrification Weeks, we will present various electric drive units and show their technical specifications, application potential and explain what benefits they offer. We will also highlight obstacles to development and present exciting examples of innovations from hofer powertrain.  

 

Get in touch, share your thoughts and submit questions that our experts will address in more detail during the Electrification Weeks in interviews or in posts on our social media channels.

Send an email to: marketingteam@hofer.de

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Discover our Electrification Weeks

We launched our electrification weeks to give you an insight into our automotive electrification expertise and industry know-how.