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SiC TECHNOLOGY

ROHM in Formula E

As an official technology partner of VENTURI Formula E Team, ROHM has been supplying SiC power devices since Season 3.

The biggest difference between battery-driven Formula E and other motor sports is power management. And how to most efficiently manage the available (electric) power is often the key to victory.
Perhaps the most important factor in determining whether the electricity is used without waste is the performance of the inverter which controls the electricity from the battery and sends it to the motor.
This is where ROHM is taking up the challenge.

Effects of SiC power devices
in Formula E

The SiC power module used in the inverter of VENTURI Formula E team’s race car utilizes an original internal module structure and optimized heat dissipation design to improve current throughput. Furthermore, switching loss is reduced by 75% (at a chip temperature of 150°C) compared with conventional IGBT modules with similar current rating. This makes it possible to achieve greater energy savings in a variety of applications. And along with reducing the size of peripheral components through high-frequency operation, the effects of reducing switching loss are greater when driving at high frequencies, contributing to the miniaturization of cooling and other systems
As a result, adopting this full SiC power module in the inverter block that comprises the core of the drive system reduces the size and weight of the inverter by 43% and 6kg, respectively, compared with the SiC-equipped inverter used in Season 2.

Also, from Season 5 ROHM began providing gate drivers, which are used to control power devices while also synergistically provide the optimum solution for electrically driven machines.

The key to the advancement of
electric cars is the inverter.

Sophisticated control of electricity is essential not only for race cars used in Formula E, but commercial EVs and HEVs as well that run on normal roads.

Currently, in the development of EVs increasing battery capacity and improving the power savings and rotational performance of motors continue to pose a challenge to designers. Meanwhile, the inverter which is responsible for controlling the electricity from the battery and sending it to the motor must balance the important themes of ‘improving efficiency’ with ‘increasing miniaturization’.
Improving efficiency means to minimize loss when sending electricity from the battery to the motor, while increasing miniaturization refers to reducing not only the size of the inverter itself, but the peripheral devices as well such as the cooling mechanism in order to decrease the size of the entire system.
Overcoming these two issues will make it possible to significantly increase driving distance at the same battery capacity or maintain the same driving distance using a smaller battery.
To meet these needs, in recent years SiC has garnered increased interest in the EV field due to the ability to dramatically improve inverter performance.

SiC Power Devices

SiC is a compound semiconductor composed of silicon (Si) and carbon (C). Rarely found in nature, SiC can now be produced artificially, but requires high quality refinement and processing. ROHM was the first in the world to successfully mass produce SiC MOSFETs. A major advantage of SiC power devices is significantly higher power conversion efficiency compared with conventional semiconductors. As a result, much less heat is generated during conversion, making it possible to dramatically reduce device size - including the cooling mechanism. These superior features are attracting increased attention, driving the demand for SiC in a wide range of fields requiring higher power and voltages. As a pioneer and leading supplier, ROHM continues to be at the forefront of technology and quality for SiC.

INTERVIEW

Franck Baldet, CTO,
VENTURI Formula E Team

Formula E is the ideal motor sports platform for testing the latest technologies for next-generation electric vehicles. We are extremely happy to have established a technical partnership with ROHM in the area of power management, which can often affect the outcome in Formula E races.


By adopting ROHM’s full SiC power module, we were able to bring to reality a lightweight inverter requiring only a minimum amount of space. This latest technology will allow us to dramatically reduce our lap times, and going forward we hope to be able to continue our collaboration and introduce groundbreaking technology through our partnership with ROHM.