System Voltage Requirements
HEVs commonly use lower-voltage systems (typically 48V–300V), while PHEVs often employ higher-voltage systems (e.g., 300V–400V) to accommodate larger battery capacities and extended electric-only driving ranges. Higher voltages in PHEVs necessitate more stringent isolation barriers to mitigate risks of leakage or arcing.
Isolation Monitoring Complexity
Both vehicle types use insulation resistance monitoring to detect faults between the high-voltage system and chassis. However, PHEVs face stricter demands:
- Extended electric operation: PHEVs rely longer on high-voltage systems during electric-only driving, requiring sustained isolation integrity.
- Larger battery packs: PHEVs’ higher-capacity batteries increase surface area and potential leakage paths, demanding enhanced monitoring sensitivity.
Architectural Integration
- HEVs often pair 12V/48V systems with internal combustion engines, simplifying isolation requirements for smaller high-voltage subsystems.
- PHEVs integrate higher-voltage architectures (e.g., 400V) with stepped-down subsystems, necessitating robust DC-DC converters and redundancy in isolation barriers for electronics.
Safety Standards
While both adhere to 60V+ safety protocols, PHEVs prioritize higher dielectric strength in components due to elevated operational voltages and extended exposure to high-voltage states during charging and driving.
In summary, PHEVs enforce more rigorous isolation standards due to higher operational voltages and prolonged high-voltage usage, whereas HEVs balance isolation needs with simpler hybrid architectures.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-high-voltage-isolation-system-in-phevs-differ-from-that-in-hevs/
