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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - DRIVEMODE (Integrated Modular Distributed Drivetrain for Electric/Hybrid Vehicles)

Teaser

Summary

We foresee that the future of mass produced electric vehicles lies in the unification of the components for the whole model line-up. The same drive modules will be used in very light cars and in high performance vehicles as well as in middle-sized and some heavy-duty vehicles.
Another important perspective into the future is the simplicity and modularity in vehicles, which enable flexible utilities. The distributed drive will dramatically change the stability control and the way of steering and braking. The possibility to integrate the functions of steering assistance, braking, and ABS into the drive control will eliminate many parts and lower the requirements for maintenance.

Efficient and pollution free mobility is a major demand, which is faced by all countries. Limited availability of fossil resources and health problems due to burning of gas and oil are forcing to search and develop new technologies in order to avoid or at least reduce these problems. This challenge is enhanced by established mobility behaviour in industrialized countries and by additional demand on individual mobility as well as on transportation of goods in emerging markets. Electric powertrains has provided efficient and pollution free mobility for several decades, but not in automotive industries. The main reason is the limited driving range due to expensive and heavy batteries. However, the other electric drivetrain components, like the electrical motor and the converter, contribute also to higher costs of new energy vehicles.

The DRIVEMODE concept stems from the idea of integrating technologies (used in electrical machines and in power electronics) to provide highly efficient and compact integrated modular drivetrain components dedicated to different kinds of cars. These include mass produced electric and hybrid vehicles, low performance and high performance vehicles and different types of heavy-duty vehicles.

In order to gain wide acceptance and commercial adoption by consumers, electric light duty vehicles have to meet the technical, economical, and user centric demands in the conservative automotive business. Regarding the optimal design and performance of such fully electrical vehicles, the electric powertrain is the key. DRIVEMODE will develop and demonstrate a novel concept for a distributed and modular fully electric and hybrid drivetrain for mass production and combining compact size, optimized manufacturability, and price.

The design proposed by DRIVEMODE is scalable to a wide variety of light duty vehicles from small city cars to powerful all-wheel-drive sports cars. The distributed electric drivetrain by DRIVEMODE is applicable in different power classes and topologies by multiplying the scalable integrated drivetrain module (IDM) according to the needs and specifications of the application. In fact, with the nominal power of a single IDM being set at 35â€“55 kW (having also a short-time overloading capability), it will potentially allow utilization of the IDMâ€™s also in heavy-duty vehicles such as electric buses.

Work performed

The project evaluated the current state of the automotive market to find the optimal requirements for the drivetrain. The collected statistical data allowed clustering the current vehicles in specific categories that can be covered by different number of integrated drivetrain units, providing in that way the scalability and distributed driving concept. Based on the analysis outcome the requirements for each subcomponent were derived, such as inverter, motor, gearbox.

On the next step, the project in an interactive manner has gone through concept generation, selection and evaluation. Only for gearbox solution, more than five concepts were evaluated for different operational points. Based on the objectives of the project the final concept has been selected providing the best synergy between components.

Following concept selection, each component has gone to the detailed design procedure. At this stage, the optimal performance from energy efficiency and manufacturing production was achieved on the component level.

Now the manufacturing of components is in its final stage and some parts are already undergoing the testing procedures.

The obtained results were distributed through the project website, videos on YouTube, posts through LinkedIn network. Partners has made several conference publications and participated to the number of events. The journalistic article was published with interviews of partners. This activity brought the visibility to the project from the targeted audience.

Final results

A key to the cost effective mass manufacturing is unification of the components among the whole performance range of vehicles â€“ from light vehicles, through C and D class passenger cars, to performance cars and light duty vehicles and buses. This part of the work was concentrated on requirement analysis and developing precise refined specifications for the components. Trends in automotive industry are analysed and specifications are developed according to the most promising technological solutions (high voltage battery, unification of the component base, wide bandgap power semiconductors, and high-speed technology).
Electrical machine, which can operate at high speed, provides more power than a low speed machine having the same dimensions. High-speed machines are more compact for a given output mechanical power. However, some obstacles are arising with higher speeds as cooling, noise, vibration, and harshness (NVH), centrifugal forces, bearings. Numerical optimization techniques will be used to minimize mass, torque ripple, and costs and to maximize energy efficiency in the same time. Fast switching SiC-modules of the converter support the increasing of power density of electrical motors.
The electrical motor is developed that has maximum speed of 22000 rpm with power density of 3.5kW/kg. Which is significantly higher compared to the solutions on the market. The peak efficiency of the motor is around 97%.
The main task of the converter is to control power flow between the electrical machine and a primary energy source, e.g. a battery. A high-speed electrical machine as a part of the integrated solution needs a high frequency power supply. Novel SiC components is used in order to ensure robust operation even at elevated frequencies. Moreover, SiC components are foreseen as the upcoming mass-market components for the most efficient drives. Usage of high voltage 800 V with SiC fast switching inverter provided the inverter power density of 35 kW/l and efficiency above 98%.

In order to provide flexibility for mass manufacturing of the vehicles utilizing the concept of distributed drive, all components are integrated within one compact and lightweight frame sharing the same cooling circuit. The module is interfaced with vehicleâ€™s thermal management system, battery, wheel drive and vehicle control system. This should significantly simplify the installation for the car manufactures and reduce the amount of components and raw material used.