Design of an Automatic Control Algorithm for Energy-Efficient ...

3 System description 32
influences like air temperature it can be written as follows:
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This relationship can be measured and put into a look-up table. Another way are prede-
fined and limited flap positions which are calibrated once and then only used in combi-
nation. This is found in many cars as a control option for the air distribution and in its
simplest case for the recirculation flap (full/none).
3.3 The heat pump
The heat pump is based on a thermodynamic cycle that is able to transport heat efficiently
by the means of a compressed (and condensed) refrigerant and a subsequent expansion.
One example is the cooling in today’s cars which is done this way. The simplified func-
tioning of such a cycle is seen in Figure 3.9.
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Figure 3.9: A simple vapour-compression refrigeration cycle diagram.
In an electric car the same concept as for the cooling should be used for the heating
in one single cycle. This requires a more complex system, additional valves and slightly
different components. Even more complexity is added by using the electric components
as a heat sink (and source) as well and not only the ambient air
Such a complex heat pump cycle with all its valves (in Figure 3.10 denoted as “V”),
expansion valves (“EV”) and an internal heat exchanger (“IHX”) to increase efficiency is