Page 113 - NEW Armstrong Book - 2

Onsemi Brings
Silicon Carbide to
Formula E Power Inverter
P
ower inverters made using silicon carbide can improve vehicle performance, allow-
By Maurizio Di Paolo Emilio
what we learn can be applied to com- mercial solutions, but the torque ratios are very different from what you find in a normal car.”
The heart of a Formula E vehicle is the powertrain, the propulsion system, which comprises the battery, inverter, and motor. The inverter is the brain of the system. It is responsible for con- verting the direct current taken from the battery into a high-density alter- nating current to be sent to the engine. During deceleration, the regenerative motor brake is activated, and the cur- rent’s path reverses.
SiC technology
As a wide-bandgap semiconductor, SiC exhibits larger bandgap energy than
silicon (3.2 eV versus 1.1 eV). Because more energy is required to excite a valence electron in the conductive band of the semiconductor, higher break- down voltages, higher efficiency, and better thermal stability at high tem- peratures can be achieved. The main advantage of a SiC MOSFET is the low drain-source on-resistance (RDS(on)), up to 300× to 400× lower than that of silicon devices at the same breakdown voltage.
The benefits of using SiC technology in inverters include smaller circuits and lower weight, improving weight dis- tribution and reducing overall power consumption. This is because SiC MOSFETs can be operated at a much higher switching frequency, reducing the size of many of the circuit
ing increased torque and acceleration.
Onsemi is partnering with Mercedes AMG’s High Power Performance (HPP) division and the Mercedes-EQ Formula E team to develop next- generation electric powertrains equipped with SiC inverters for race cars that compete on the ABB FIA World Championship circuit.
In an interview with EE Times, Dave Priscak, vice president of global sys- tems engineering at onsemi, high- lighted how design and testing go hand in hand in Formula E, enabling the con- tinuous improvement of the inverter power stages. “When we started in Formula E, we came in as a sponsor, working only with the Mercedes team, and we were looking for some ways to show what we did and are doing for the electric vehicle market,” said Priscak. “But very quickly, working with their development team, we realized that there is a lot we can learn from each other from an engineering perspective. And so it became more of a partnership than a sponsorship.”
Formula E is the only motorsport event to test the latest EV technologies. “Our design engineers are working with the powertrain engineers at Formula E to develop the next generation of traction inverters and power transfer systems for Formula E,” said Priscak. “Most of
FORMULA E CAR (SOURCE: ONSEMI)
99