Shorter charging times, lower cable weight, and, ultimately, better driving performance — these are the advantages of 800 V systems in the field of e-mobility and charging infrastructure. According to Ohm’s law, increasing the voltage while maintaining the same power leads to a reduction in current. However, to be honest, the efficiency boost in the case of 800 V systems is not primarily due to the higher voltage but to the SiC power semiconductors used. Technically, the same effect could also be achieved by increasing the current in the system, but this would require larger cable cross-sections, which would make the cables used thicker, heavier, and more expensive. Added to this would be the thermal load on the vehicle’s power electronics and the thermal load on the CCS connectors, as this depends directly on the current.
From today’s perspective, an 800 V structure is really only worthwhile for larger electric cars and long-distance journeys. According to experts, vehicles with a 58 kWh battery would only charge at 175 kW even with an 800 V architecture. This charging capacity can easily be achieved with a 400 V network. The decision to switch to 800 V has consequences. Almost all high-voltage components have to be redesigned, from the battery and drive unit to the charger and DC/DC converter. Thermal management and components such as the air conditioning compressor and high-voltage heater are also affected. The switch to 800 V therefore means additional work.
If the car manufacturer has decided to switch to 800 V, it can use this decision to eliminate two pain points that are still preventing many potential electric car buyers from making the switch. An 800 V vehicle can be charged from 10 to 80 percent of its battery capacity in less than 20 minutes using a high-power charger (HPC). With the appropriate SiC- or GaN-based power semiconductors, the voltage could certainly be increased even further. To date, the power semiconductors used in 800 V systems have reverse voltages of 1200 V. If reverse voltages of 1700 V or even 2000 V and above were used, batteries could certainly be charged at higher rates than 10C.
When used sensibly, an 800 V system in an electric car leads to higher overall vehicle efficiency, which translates into a longer range, as less energy is converted into heat. More efficient SiC- or GaN-based power electronics in these electric vehicles, which generate less heat, also improve the efficiency of air conditioning. Since significantly thinner cables are required for power transmission at 800 V than at 400 V, the overall weight of the vehicle is reduced. This has a direct impact on driving performance, for example in the form of better acceleration or cornering behaviour. Finally, due to the lower losses in 800 V systems, it is possible to deliver higher continuous power to the motors. Those who drive sportily or accelerate frequently will notice that the power output drops less than with previous systems.
The only current disadvantage of 800 V systems in e-mobility is the fact that many standard components, such as air conditioning compressors, heat pumps and DC/DC converters, are currently still designed for 400 V and are produced in large quantities. With the current low production volumes of 800 V components, economies of scale are still lacking. However, it can be assumed that in the long term they will approach the price level of 400 V technology.
In the following articles, experts from Infineon Technologies, onsemi and Nexperia explain the advantages of 800 V architectures based on SiC technology in e-mobility, both in vehicles and in the charging infrastructure. eg
