Using SiC technology for transducers is a good way to increase torque and acceleration and enhance the vehicle’s overall performance. ON Semiconductor is partnering with Mercedes-EQ Formula E in the Formula E World Championship to develop the next generation of electric motors. The technical cooperation between ON Semiconductor and Mercedes-AMG’s High Power Performance Division (HPP) has provided technical improvements to the racing cars. In an interview with EE Times, Dave Priscak, Vice President, Global Systems Engineering at ON Semiconductor, highlighted how design and testing go hand in hand in Formula E, enabling continuous improvement of the inverter’s power phases. “When we started in Formula E, we came in as a sponsor, we only work with the Mercedes team, PETRONAS – and we were looking for some ways to show what we’ve done and what we’re doing in the EV market. But very quickly, by working with their development team, We realized there was a lot we could learn from each other from an engineering perspective. And so it became more of a partnership than a sponsorship. Our design engineers are working with Formula E powertrain engineers to develop the next generation of traction converters and powertrains for Formula E. Most of what we learn can be applied on commercial solutions but the torque ratios are very different from what you’d find “in a normal car,” Bressack said. The heart of a Formula E vehicle is the power unit, the drive system, which is made up of three components: the battery, the inverter, and the motor. The inverter is the brain of the system. It’s responsible for Converting the direct current taken from the battery into a high intensity alternating current to be sent to the engine.However, during deceleration, the regenerative engine brakes are activated, and the current follows the reverse path.Formula E is the only motorsports event to test the latest technology in electric cars of the next generation. SiC Technology As a wide bandgap semiconductor, silicon carbide exhibits a larger bandgap energy than silicon (3.2 eV, three times higher than that of silicon, equal to 1.1eV). Since more energy is required to excite the valence electron in the conducting band of the semiconductor, higher breakdown voltage, higher efficiency and better thermal stability can be achieved at higher temperatures. The main advantage of SiC MOSFET is its low drain-to-source resistance (RDS (ON)), which is 300-400 times lower than that of silicon devices at the same breakdown voltage. The advantages of using SiC technology in transformers include smaller circuits and lower weight, improved weight distribution and reduced overall power consumption. This stems from the fact that SiC MOSFETs can be operated at a much higher switching frequency which reduces the size of many circuit elements required in the inverter. SiC devices can also operate at higher voltages and currents than standard silicon power semiconductors, increasing power density and reducing switching losses even at high temperatures. S7_ DIRIYAH, Fri, February 26, 2021 – Sebastian Cauca Racing Power Inverter Formula E provides insight on how to increase efficiency and extend battery life. Priscak noted that there’s a lot of design focused on how to transfer power in the powertrain as efficiently as possible. Racing cars need technology that can withstand extreme shocks, strong vibrations and extreme temperatures. In addition, the higher the efficiency of the semiconductor device, the less power dissipation and heat waste, which leads to an improved power-per-watt ratio. At the same time, engineers also aim to reduce the components of their cars to save weight and space. In the Formula E space, silicon carbide is almost exclusively, Priscak noted. The stage of power from the battery to the motor is very simple. However, the motor drive is a very complex mathematical algorithm, but the power transmission is not much different from today’s electric vehicles. “The problem is that in Formula E you have to be on track for 45 minutes with a lot of acceleration and braking. So the biggest challenge is getting back as much power as possible. And that’s very difficult. Because you have big, short bursts of energy, Batteries can’t absorb all of that.” Right now, some of the biggest challenges when it comes to the powertrain are being able to capture all the power while braking and virtually charge the battery. Competition rules only allow one battery per race, so the goal is to work on the technology Not only to recover as much of it as possible but to use it as efficiently as possible.Electric energy storage technology (often considered the biggest enabler and limiting factor for an electric vehicle) is what carries electricity and supplies it to an electric motor.There are various technologies for storing electrical energy, such as capacitors Superior, chemical batteries, solid state batteries, etc. Today’s chemical lithium-ion batteries offer the most practical balance between performance and commercial viability.Creating the next generation of gate drivers is another area of focus It is ON Semiconductor, in order to maximize the conduction area of the silicon carbide MOSFET. “The difference is that the race, as I said before, should only last 45 minutes, while the car should last 10 years. So by pushing the limits of silicon carbide performance, we are learning how to maximize life. In Formula E, we focus on The entire powertrain, from the digital processor to the actuator. Not just the silicon carbide, but also the gate design, driver design, isolation fender, all the elements that determine the efficiency of the powertrain,” Brisac said. Monitoring is critical in Formula E. It is important to measure every ampere of current circulating through the car. Every time you increase speed, brake or cornering, you need to understand not only how much energy is lost but also how much energy can be regained. If the driver is too aggressive, Brysac noted, the battery will never reach the finish. So there is monitoring of the drive profile, acceleration and braking in particular, and analysis of every aspect of the drive line. “In all of this, temperature is important, both from a battery standpoint to make sure the terminals don’t get too hot during acceleration and at all power phases to monitor the temperature. There are a lot of sensors not just for current and voltage but also for temperature,” Brisac said. Silicon carbide is a very fast, high-voltage switch, and the biggest challenge Bressac noted is driving the motor.” The motor is a big inductor that hates fast switching. If you have a quick switch in the motor, the motor wants a sine wave. Silicon carbide turns much faster than the inductive load can handle. “So there has to be continuous innovation in the way we drive motors,” Brisac said. Formula E is pushing the boundaries of power electronics technology and driving a range of new SiC solutions. Electric vehicles will benefit from new SiC energy solutions by having simpler cooling systems, longer range and better performance. It will also extend the life of the electric car’s battery, and charging the battery will be much faster with improved built-in chargers (OBCs) and DC inverters. The numerous partnerships between chip companies and Formula E will benefit e-mobility through various engineering solutions not only from SiC chip manufacturers but also from GaN chip manufacturers. .
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