Integrated Modular Distributed Drivetrain for Electric/Hybrid Vehicles

Project Information

DRIVEMODE

Grant agreement ID: 769989

DOI

10.3030/769989

Project closed

EC signature date 9 August 2017

Start date 1 November 2017

End date 31 March 2021

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 9 519 067,50

EU contribution

€ 9 519 067,50

Coordinated by

TEKNOLOGIAN TUTKIMUSKESKUS VTT OY
Finland

Periodic Reporting for period 2 - DRIVEMODE (Integrated Modular Distributed Drivetrain for Electric/Hybrid Vehicles)

Reporting period: 2019-05-01 to 2021-03-31

Summary of the context and overall objectives of the project

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 35–55 kW (having also a short-time overloading capability), it will potentially allow utilization of the IDM’s also in heavy-duty vehicles such as electric buses.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the beginning of the project, the following targets were set as the main orienteer for the final design of the DRIVEMODE IDM:
- 50% increase in e-motor speed
- 800V voltage for material reduction and fast charging
- 30% increase in specific power
- 50% reduction in losses

During the project, each of these targets were achieved via various technologies. For example, the high-speed machine has high torque and power and small size by using thin lamination material, lowered winding current density, semi magnetic wedges, and advanced optimization technologies. A high voltage battery was used in DRIVEMODE vehicle. This choice decreases the required copper weight, simplifies the motor operation at high speed, improves the efficiency of the SiC drive, and reduces charging time in comparison with typical 240V DC systems. The utilization of SiC chips itself reduces the switching losses significantly, which allows to downsize the thermal management equipment in comparison with the same power and frequency Si devices.

The DRIVEMODE drivetrain 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. Therefore, the design is scalable to a wide variety of EVs from small city cars to powerful all-wheel-drive sports cars and heavy-duty vehicles such as electric buses. A mid-sized C-segment car was selected for concept demonstration in DRIVEMODE. Further information on the specification of DRIVEMODE drivetrain and vehicle is available on the DRIVEMODE Final Book (http://drivemode-h2020.eu/wp-content/uploads/2021/03/Drivemode-Final-Book-A5_low-res.pdf).

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

A key to the cost effective mass manufacturing is unification of the components among the whole performance range of vehicles – 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 were analysed and specifications were 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 were 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 was developed with maximum speed of 20000 rpm with specific power of 3.4 kW/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 was 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 was 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 42 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 were integrated within one compact and lightweight frame sharing the same cooling circuit. The module was interfaced with vehicle’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.

DRIVEMODE Integrated Drivetrain Module