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P_Comp_M P_Comp_E Veh_Speed power of powertrain components can be
reduced in advance and the HV battery
5990 140
4990 120 can be passively cooled.
100
P_Electric [W] 2990 80 Vehicle speed [km/h] PREDICTIVE CONTROL OF
3990
60
AIR CONDITIONING SYSTEM
40
1990
990 20 The solar radiation towards the passen-
0
-10 -20 ger compartment leads to a significant
0 200 400 600 800 1000 1200 1400 1600 1800 increase of cooling power demand dur-
Time [s] ing summer time. While driving through
a tunnel, this impact is not present and
30 the necessary cooling power is reduced.
T_Cab_M On the other hand in winter time, an
28
T_Cab_E increased heating power demand is pres-
26
T_Cabin [°C] 24 ent if the vehicle cannot use the contri-
bution of solar radiation while driving
through a tunnel. In this case, the ther-
22
mal mass of the battery can be used to
20 supply excess heat to the heating circuit.
18 Generally it is valid that in favour of
0 200 400 600 800 1000 1200 1400 1600 1800 energy efficiency, different components
Time [s] can be used as heat sources within their
FIGURE 3 Cool-down of the cabin and the respective power for a mechanically (light green) and electrically allowed operational temperature win-
(dark green) driven compressor in WLTC (© qpunkt) dow. This can be done by supplying
their waste heat by direct mixing or via
heat exchangers into the heating cycle
and supporting passenger compartment
predictive control in this case neglects it will be cooled via the main radiator comfort. By smart control, thermal
the cool down by reducing the pump in the Low Temperature (LT) cycle. No masses can be employed by reducing
speed in the battery cooling cycle. active, electrically powered component cooling by the same amount as the
Again, the prevention of premature bat- is used for generation of cooling power. in passenger compartment heating
tery aging due to too high cell tempera- This suggests, that as much as possible demand is expected to increase due to
tures needs to be considered when used passive cooling should be utilised to meteorological conditions and upcom-
as heat storage. achieve maximum energy efficiency. ing course of the road. Under appropri-
In battery cooling mode, one can dis- Since the LT cooling cycle also serves ate traffic conditions, for example heavy
tinguish between active and passive other components such as electric traffic, the necessary traction power
cooling. The active cooling is based on motors, gear boxes etc., and the low tem- and the cooling demand of the HV bat-
thermal coupling of the cooling cycle perature heat exchanger can only pro- tery can be predicted well because
and the refrigerant cycle via a heat vide a certain cooling power, the operat- within certain boundary conditions the
exchanger. The cooling power corre- ing range to passively cool the traction vehicle will just follow the general traf-
sponds to the power generated by the battery is limited. When recognising a fic. In terms of utilisation of thermal
compressor. In case of passive cooling, downhill driving passage, the cooling masses this option of predictive calcula-
tion leads to a benefit.

REFERENCES
[1] Weustenfeld, T. A.; Bauer-Kugelmann, W.;
Menken, J. C.; Strasser, K.; Köhler, J.: Heat flow
rate based thermal management for electric
vehicles using a secondary loop heating and
cooling system. Conference Vehicle Thermal
Management Systems Symposium and Exhibition,
Nottingham (England), 2015
[2] Gregorcic, G.; Oberlechner, F.; Drage, P.:
Modeling and control of thermal cycles in vehicle
electrification. To be published in Proceedings of
the IEEE 25 th Mediterranean Conference on Control
FIGURE 4 Functional prototype of and Automation, Malta, 2017
an indirect heat pump; the main [3] Menken, J.: Thermomanagement im batterie-
components are high voltage (HV) betriebenen PKW unter Nutzung eines Kaltdampf-
compressor, chiller, indirect prozesses mit Sekundärkreislaufsystem. Braun-
condenser (iCond), internal heat- schweig, Fakultät für Maschinenbau der Tech-
exchanger and electrical expansion nischen Universität Carolo-Wilhelmina zu
valve (EXV) (© qpunkt) Braunschweig, dissertation, 2015
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