Why Higher Voltage Better For Cars
Did you know your car probably still use 12V or 48V components when the world outside cars are using much higher voltage.
One of the major underrated improvements that even Elon Musk from Tesla has preached is the use of higher voltage for cars in the interview with Sandy Munro.
Why are higher voltage better for cars? Higher voltage allows to reduce bulky wiring harnesses running throughout the vehicle; it is said that a voltage increase of threefold could potentially reduce the size of the cable bundle by 50%. The turbocharger also improved with the use of higher voltage. Overall, the reduction will cut costs and weight and make a car cheaper to produce and better in users' experience.
The reasons why everyone is stuck at 12V and 48V is due to
- Difficulties of getting car parts that work at a new higher voltage.
- Much higher voltages make insulation difficult (particularly in damp automotive environments), 12V or 48V is low compared to power over ethernet (PoE) which is over 40V
Therefore, one of the solutions was
- Use of dual motors (12V and 48V motors) to minimize impact; or
- Use of 48V and a dc-dc converter for 12V components.
The higher 48V is best used for start-stop motors, turbochargers, power steering, brakes, air conditioning, and other systems. The lower 12V is retained for less important devices such as lighting, infotainment. The hybrid approach is claimed to produce two-thirds of the benefit of a full hybrid at one-third of the cost while increasing efficiency by up to 20%.
At an age, where the car is focusing on efficiency (nowadays your car even turns off when idle for a few seconds in traffic), any savings to extend the range of the car are desired. In the future, you can also expect the idle shutdown to be more seamless, with the use of better integration.
Electric Turbocharger with Sufficient Voltage
Electrifying a turbocharger also has significant benefits. Typical turbochargers suffer from turbo lag. Exhaust gases that power the impeller (i.e., the turbine blades) need to increase its speed from a fixed position to between 100,000 and 200,000 RPM as fast as possible, otherwise, you have turbo lag.
If the turbocharger was powered by a 48-V system, it could spin up the impeller so fast as to make turbo lag virtually imperceptible. Some automakers are combining this approach with a turbocharger, which is typically driven by a belt powered by the engine. However, in this case, power is supplied by an electric motor. The result is a greater power, reduced load on the engine, and better fuel economy.
What is the safety regulation for high voltage in cars?
Safety regulations “High voltage” in cars is defined as 60–1500V. As such, if you dismantle an electric car like Tesla, you will see the "High Voltage" warning in their battery packs which are easily over 400V.
What are the requirements for a vehicle safety inspection?
If you go above 1500Vdc, a completely different set of electrical safety requirements comes into play, which requires additional safety regulation compliance - usually including extra safety equipment, certain ratings for materials used, clearances, and lots and lots of safety documentation and certification for both the manufacturing and testing of the vehicle; drivers of the vehicle; maintenance of the vehicle; and emergency responders working on the vehicle in the event of a crash.
What is the risk of >1500Vdc?
I'm not currently aware of whether >1500Vdc is even allowed or legislated for in vehicles, there's a possibility that no existing safety framework exists. Tesla's documentation intended for first responders does show which wires to cut to disable the high-voltage system to prevent electric fire.
At higher voltage, Insulation thickness in motor windings, and the number of turns, and the coil geometry in motors needed to produce the same torque are considerations by the manufacturer.
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