Issue link: https://te.mouser.com/i/1450905
TE Connectivity White Paper /// Thermal Modeling for High Power Charging (HPC) of Electric Vehicles Page 6 Thermal Modeling for High Power Charging (HPC) of Electric Vehicles availability of all interconnection components along the high voltage / high current path. 5. The Importance of Thermal Simulation The physics of transmitting electric energy causes power dissipation in the shape of heat losses along the wired energy flow. The root cause is the electrical resistance (measured in Ohm/Ω) of all metallic conduc- tors. This resistance is known for every element of the high voltage path. However, the ohmic resistance changes with the temperature in- crease during operation. The amount of power dissipation that occurs at a specific component can be calculat- ed for a certain current, voltage and temperature – albeit only for a sta- tionary state when all paths of heat dissipation are balanced. Existing methods to calculate dy- namically the complete high volt- age path on a system level are not very practical. In order to apply a well-known method such as the finite element analysis (FEA) it would be necessary to make multiple cal- culations in rapid sequence for each operating point. Now, a continu- ing thermal calculation in real time (in the vehicle) requires a different methodology which requires much less computing power. One part of the challenge is that heat dissipation along a high voltage path leads to a comparatively slow sys- tem. Depending on an individual component's mass and the adjacent available heat sinks, the individual component will react differently to changing load profiles. Light-weight components with a limited chance for heat dissipation can therefore turn into a bottleneck for thermal management. If the generated heat cannot be sufficiently dissipated, the component will temporarily become adiabatic element (i.e. a condition with no heat exchange with the en- vironment) without any chance to externally influence its heating-up process. Thermal bottlenecks of that type need to be understood so that no unnecessary limits or stress are based on the system. Furthermore, heat dissipation oc- curs on several paths. In addition to conductive heat dissipation within the material, there is also the share of heat radiation and heat dissipa- tion via cooling air or coolant flows (convection). For each component along the high voltage path the mix of these three elements will be dif- ferent. For instance, the inlet offers comparatively beneficial conditions for heat dissipation because some heat losses are transported away via the active cooling of the combined charging system (CCS) connector. However, the battery connector, has no such active heat sink. This means that the conditions for heat dissipa- tion are different at one end of the cable connecting inlet and battery from the conditions at the other end. When electrical components heat up they also undergo an aging process which changes the electrical (and/ or mechanical) properties of the component over time. The stronger the heat entry, the faster this aging process and the smaller the resid- ual performance level of the com- ponent. Considering the typical as- sumed vehicle life of (300.000 km, 15 years, 8000 hours of operation), the aging of every component is in- fluenced by the actual load profiles. With the addition of 30.000 hours Fig. 3: Differently stressed components along the current path of an EV.