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FIGURE 3 Thermal management requirements for
battery-electric vehicles – a coolant side HV
heater as solution (© Mahle Behr)

in comparison with the HV heater. The ing a tank with fuel, however, charging a the installed low-temperature circuit.
reason for this is the significantly greater battery is subject to losses due to physical Above this temperature, the refrigerant
efficiency of the heat pump at 3.2. This is constraints. The faster the charging pro- circuit must provide active cooling. The
offset by greater installation effort and cess, the higher the electrical current design of such a rapid charging system
substantially more complex thermal needed and thus the higher the losses due for the critical case (T ambient = 40 °C)
management, as new interfaces arise, to heat. In order to rapidly charge the bat- must also maintain the cabin tempera-
FIGURE 5. Additionally, the utility of a tery, while protecting it from premature ture constant (about 3 kW), so that the
heat pump drops as the drive power or aging, active cooling that incorporates all system must dissipate a total of about
size of the powertrain increases. existing cooling circuits is needed, depend- 15 kW. By comparison: current systems,
ing on the outside temperature. For rapid dedicated solely to interior cooling, use
charging, for example, the air conditioning about 8 kW for cabin cool-down.
FAST CHARGING – CRUCIAL
FOR ACCEPTANCE OF must provide up to 12 kW just for battery
ELECTRIC MOBILITY temperature control when the outside tem- FUEL CELLS – SPECIAL
perature is high (100 kWh battery capacity, REQUIREMENTS FOR THERMAL
Another requirement for modern electric rapid charging in 15 min, 80 % SOC). MANAGEMENT
mobility is significantly shorter charging At moderate or low outside tem-
times for the electric energy store, which is perature – below about 15 °C – this Thermal management plays an impor-
currently still quite long. In contrast to fill- amount of heat can be dissipated via tant role in vehicles powered by fuel

FIGURE 4 Cruising range of plug-in hybrid vehicles and
battery-electric vehicles at 0 °C ambient temperature
(© Mahle Behr)

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