The high-pitched whine that a Formula E electric vehicle makes at race car speed is primarily coming from the gearbox, and it’s one of the only sounds the car emits.
I am just returning from an amazing visit to the final Formula E race of this 2017/2018 season in the town I grew up in: Brooklyn, NY. I was invited to attend the race by the Venturi team and ROHM semiconductor, who supplied the SiC-based power inverter to drive the 120 kW McLaren E-Motor from the stacked battery voltage output. I wrote about that architecture on Planet Analog.
The McLaren 120 kW E-Motor is a synchronous permanent magnet motor/generator (Image courtesy of McLaren)
What an amazing experience. I was especially intrigued with the low whining sounds coming from these electric race cars because at stock car races I have attended the high-rev gasoline engine noise is so loud that you can’t hear people comment or cheer. One of the nice things about a Formula E race is that you can hear people cheer for their favorite team and driver and you can easily speak to people around you.
The high-pitched whine that a Formula E electric vehicle makes at race car speed is primarily coming from the gearbox. Racing transmissions use straight-cut gears that whine a bit. In Formula E’s case, it’s one of the only sounds the car emits. The gearbox has to feed into a mechanical differential, per the regulations, which probably adds to the sound. A Tesla uses more silent helical gears, but a race car does not need to be silent; although the cars are nearly silent at lower speeds so team members need to be aware of a car coming into the Paddock area.
The only other noise is the tires. They are harder than most race tires and squeal when the vehicle slides and drifts around turns. Listen to the sounds of the Formula E cars as they speed around the track corners in a pole-position run I witnessed in Brooklyn:
Season 5 will see a new vehicle with a total power of 250 kW, as opposed to the present 200 kW vehicles (see Gen 2 Formula E racing car: Batman would be envious). The new car will have a top speed capability of 174 mph (IndyCar, NASCAR, and Formula One are at 200 mph). The Formula E cars race on tight-turn street tracks, unlike the other gasoline racers mentioned here. Present Formula E vehicles need two cars for the full race due to battery capacity, but the new vehicle will be able to complete the race with only one vehicle.
Test drivers of the new vehicle say that it will be louder than the present vehicles because of the extra noise coming out of the much stronger electric drivetrain, in addition to the way the wind breaks off the more complex aerodynamic body shapes.
The rationale behind Formula E is to take motorsport right into the centers of the world’s cities. That urban environment will be one of the primary uses of the electric vehicle. Formula E was created to spread the message of sustainable mobility as the world moves toward an increasingly electrified automotive future.
It all makes sense. The world’s transition to electrified motoring has started and it’s unstoppable. Countries such as France and the United Kingdom are moving to ban gasoline and diesel cars by 2040, and numerous car manufacturers have committed to electrify their entire model fleets.
Elon Musk’s Tesla produces high-end electric vehicles with nice features (The Model S starts at $74,500), although they have also produced a lower cost version with their $35,000 Model 3. BMW, Nissan, Chevrolet, Ford, Volkswagen, and Kia are some of the other top producers of electric vehicles.
Watch for my series of articles on EDN and Planet Analog about this Formula E race technology in the coming weeks. You will be amazed with the technology and innovative spirit around this event.
Steve Taranovich is a senior technical editor at EDN with 45 years of experience in the electronics industry.
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