The effect of EV battery voltage (400 volt or 800 volt) on charging technology
Zaffar, Abdullah (2026)
Diplomityö
2026
School of Energy Systems, Sähkötekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2026041026346
https://urn.fi/URN:NBN:fi-fe2026041026346
Tiivistelmä
In the proposed research, the question of interest is how the electric car (EV) battery platform voltage (400 V and 800 V) affects the design considerations, efficiency behaviour, and workability of grid-connected DC fast-charging systems. The current study takes a part-based view of battery voltage, discussing how voltage choice determines the main processes of the charging architecture i.e. the rectifier, DC link, isolation stage, output converter, and charging conductors. This analysis thus aims at explaining how voltage of battery can impact upon current flow, power losses and component stress distribution along the charging chain based on the knowledge assessed in the literature published in the academic and technical literature.
It is consistently shown in the literature reviewed that the increase in the battery and DC -bus voltage, up to a level of 800 V, reduces the amount of charging current needed to provide a given amount of power. Since the amount of electrical power is the product of current and voltage, when the operating voltage is increased, the amount of power that can be transferred remains constant, with a smaller current. This decrease in current immediately lowers resistive (I 2R) losses in charging cables, internal conductors and DC-side convertor stages, thus enhancing thermal performance, and aiding higher efficiency at high power during high-power charging. These effects are more severe in fast-charging systems that are above about 150 kW where the magnitude of the current has a strong impact on conductor losses and temperature increase in a traditional 400 V system.
However, it is also stated in the literature that the advantages that come with lower current also include the redistribution of electrical loads on to the charging system. Higher voltage operation level contributes to the higher blocking voltage characteristics of semiconductor devices, and to the insulation coordination, creepage and clearance distances and dielectric strength requirements of isolation structures. This means that, although 800 V architectures minimize losses due to current, they create more constraints in terms of voltage in multiple stages of the charging infrastructure.
That the two voltage platforms are similar and do not, in fact, replace the architectural figure of 400 V and instead represents a different engineering trade-off. Reduced current operation reduces the conduction losses and thermal stress and increased operating voltage requires component operation ratings and insulation design. Regarding the systemarchitecture side, the choice of battery platform voltage essentially influences the distribution of the losses, thermal loads and component ratings throughout the charging system.
To wrap up, this thesis presents a systematic summary of the existing studies about the relationship existing between battery platform voltage and EV fast-charging system behaviour. In comparing the electrical implications of both voltage designs in a similar analytical framework, the study offers a concise and technologically based comparison of the 400 V and 800 V EV charging platforms, hence offering insights into the design trade-offs related to highpower charging infrastructure in the future.
It is consistently shown in the literature reviewed that the increase in the battery and DC -bus voltage, up to a level of 800 V, reduces the amount of charging current needed to provide a given amount of power. Since the amount of electrical power is the product of current and voltage, when the operating voltage is increased, the amount of power that can be transferred remains constant, with a smaller current. This decrease in current immediately lowers resistive (I 2R) losses in charging cables, internal conductors and DC-side convertor stages, thus enhancing thermal performance, and aiding higher efficiency at high power during high-power charging. These effects are more severe in fast-charging systems that are above about 150 kW where the magnitude of the current has a strong impact on conductor losses and temperature increase in a traditional 400 V system.
However, it is also stated in the literature that the advantages that come with lower current also include the redistribution of electrical loads on to the charging system. Higher voltage operation level contributes to the higher blocking voltage characteristics of semiconductor devices, and to the insulation coordination, creepage and clearance distances and dielectric strength requirements of isolation structures. This means that, although 800 V architectures minimize losses due to current, they create more constraints in terms of voltage in multiple stages of the charging infrastructure.
That the two voltage platforms are similar and do not, in fact, replace the architectural figure of 400 V and instead represents a different engineering trade-off. Reduced current operation reduces the conduction losses and thermal stress and increased operating voltage requires component operation ratings and insulation design. Regarding the systemarchitecture side, the choice of battery platform voltage essentially influences the distribution of the losses, thermal loads and component ratings throughout the charging system.
To wrap up, this thesis presents a systematic summary of the existing studies about the relationship existing between battery platform voltage and EV fast-charging system behaviour. In comparing the electrical implications of both voltage designs in a similar analytical framework, the study offers a concise and technologically based comparison of the 400 V and 800 V EV charging platforms, hence offering insights into the design trade-offs related to highpower charging infrastructure in the future.