More particularly, the section concerning the battery (type:
NiMH 200V 6.5Ah similar to the one used in the Toyota Prius
THS-II) and the DC-DC converter will be studied. The purpose
of the DC-DC converter is to interface the 200V battery
voltage to the 500V DC bus voltage for the two inverters which
will supply the two permanent magnet synchronous machines,
as shown in Fig. 11.
Dynamic simulation is a principal stage in the design of
systems such as for the hybrid electric car. The improvement
3This figure was obtained from the ”Special Reports” document on the
Toyota website.
Fig. 11. HEV vehicle electrical system
of the energy management system (EMS) as well as the
dimensioning of the components can be obtained with good
exactitude with this simulation. For example, so as not to
exceed the maximum power of the battery, it is possible to
directly control the electric motor in order to limit its current.
These current peaks can be determined with precision by
dynamic simulation. In this case, the effect of the voltage
variation caused by the current’s change in the battery can be
studied and its impact on the DC-DC converter (which must
maintain the DC bus voltage at 500Vdc) can be analysed.
Obviously the results in Fig. 12 show only one small part
of the entire system. The complete simulation model of the
vehicle will be the subject of a subsequent article.