In 2017, the European Union decided to create a program for funding researches on EVs called GV-04. The goal, according to its official page, is to deliver the “next generation of electric drivetrains”, which “should be conceived to also take into account design for manufacturing, low weight, and material cost”.
One of the most interesting answers to these requests is the Drivemode Project. It has addressed these requirements by creating a single module that gathers the electric motor, the transmission, and the converter. And believes it can be used by all future EVs, from various manufacturers.
That sort of belief comes from the fact that the module is small and scalable to whatever the car project needs. The compact electric motor can have between 35 kW (47 hp) and 60 kW (80 hp), with peaks of 90 kW (121 hp). Torque would be around 100 Nm (73.8 lb-ft). Its rotor can swirl at speeds of 20,000 rpm. Mind you that the idea is to use several modules in each car. At least two of them for each vehicle, one for each wheel. So, an all-wheel drive could present up to 320 hp and 295.2 lb-ft, with peaks of 484 hp.
The high-speed transmission is said to be able to achieve a 97 percent efficiency, and the converter — made of Silicon Carbide (SiC), a semiconductor — operates in high frequencies (over 20 kHz) and high voltage (800 V). The fact that both the engine and the transmission work at high speed makes them more powerful and efficient, which allows them to be smaller and to save on material use and on the vehicle’s weight. The high voltage saves on copper since cables can be thinner to deal with the lower currents (Porsche Taycan, anyone?). That also makes recharging faster.
In the future, if cars that adopt these modules really use one of them per wheel, things like wheels that turn will be a thing of the past. Steering will be possible solely with setting different speeds to each of the wheels. The suspension system may benefit from a more predictable behavior and components such as an EPS steering system and so on will probably disappear. A drive-by-wire lever or steering wheel may be enough. Even the braking can present radical changes, but let’s leave them to the future. If it ever arrives this way.
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.
Understanding the core
The main components of DRIVEMODE shown in Figure 1 are as follows: (A) High-speed gearbox, (B) High-speed motor and (C) Silicon Carbide (SiC) inverter. They are all integrated together as one compact integrated drivetrain module (IDM) together with a high-voltage battery, controls and a cooling unit. The main components have the following features:
- Speed: 15-20 krpm to ~1.5-2.5krpm
- Power: up to 90 kW
- Power: 35-60 kW (70-90 kW peak)
- Speed: 15-20 krpm
- Frequency: >20 kHz
- Voltage: 800V DC
Advantages of these set-up include
- The high-frequency power convertor and the high-speed electrical motor will reduce the materials costs and footprint.
- The SiC semiconductor will gradually decrease the switching loses, which will improve the efficiency significantly while enabling the cars the drivetrain to operate at higher frequencies.
- The usage of high-voltage (600-900V) battery will decrease the required copper weight, therefore, simplifying the operation of the motor at high speeds and improving the efficiency of the SiC drive and reducing the charging times.
Due to all these, our drivetrain modules will be mass-produced easily and will influence dramatically the stability control and the way cars are steered and braked.
DRIVEMODE is led by the VTT Technical Research Centre of Finland and is composed by 12 partners from 6 different EU member states: Semikron Elektronik GMBH & Co. KG, AVL Trimerics GMBH and Technische Universitaet Ilmenau (Germany), Visedo Oy (Finland), Chalmers Tekniska Hoegskola AB, National Electric Vehicle Sweden AB and Borgwarner Sweden AB (Sweden), Thien Edrives BMGH (Austria), Univerza V Ljublkani (Slovenia) and, S.C.I.R.E. Consorzio and Fondazione iCons (Italy).