Information Technology Reference
In-Depth Information
The resistance force
F
res
describes the friction forces at the wheels as well as
the air resistance. It can be approximated by a polynomial
k
4
v
veh
+
k
5
v
veh
m
veh
,
(3)
F
res
=
k
0
+
k
1
v
veh
+
k
2
m
veh
+
k
3
v
veh
m
veh
+
where
v
veh
is the vehicle velocity. With the inclination angle
γ
, the inclination
force
F
inc
is given by
F
inc
=
. Then, the outputs of the forward
mode,
a
veh
and
v
veh
, follow from numerical integration.
For the backward approach, the inverse problem is considered using the
given duty cycle parameters, namely, the velocity profile
v
veh
and the ac-
celeration profile
a
veh
. Solving the equation of motion (1) for
F
wheel
leads
to
m
veh
g
sin(
γ
)
F
wheel
=
m
veh
a
veh
+
F
res
+
F
inc
.
(4)
Here, the braking force
F
brake
is included in
F
wheel
. The resistance force
F
res
and the inclination force
F
inc
can be calculated for the given duty cycle. The
outputs of the backward approach, the power variables, result in
F
wheel
d
wheel
2
, ω
wheel
=
2
v
veh
d
wheel
,
ω
wheel
=
2
a
veh
d
wheel
T
wheel
=
˙
.
(5)
2.2
Hybrid and Non-Hybrid operating Modes
Like above, for all system components depicted in Fig. 1, mathematical mod-
els were derived in form of algebraic or differential equations as well as quasi-
static maps. The control unit determines the power distribution between the
combustion engine and electrical energy storage in Fig. 1. Besides the energy
management, the operating strategy has to be determined by the control
unit. In this paper, the chosen overall operating strategy involves six differ-
ent modes.
%
$
$
!
Fig. 3. Hybrid drive strategy.
Mode 1 represents the pure engine mode, in which the internal combus-
tion engine provides the total power demand. Mode 2 is the pure electric
