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Integrated
starter generator (ISG) combines the starter and alternator with enhanced
functionality as is relates to the engine. The main advantages of ISG are providing faster starting
compared to current 12-volt starters, which makes frequent start/stop of an
engine possible, and supplying higher power for ever-increasing electrical
loads compared to current 12-volt alternators. In addition, ISG will improve
fuel consumption by making the vehicle more efficient, regenerating energy
from the braking system, and directly effect packaging issues by eliminating
and reducing the size of some modules.
In developing this product, which is a first such system on the market, CAE
modeling, simulation, and analysis of electrical components and subsystems
of an integrated starter alternator (ISG) is performed. The circuit
simulation tool Saber was used. ISG consists of three sections:
induction machine, inverter, and indirect field oriented controller. It has
been modeled using two different methods: detailed and averaged. The detailed
method gives the more accurate results, while the averaged method provides
faster simulation time. In the detailed model, all three sections of the ISG
(induction machine, inverter, and indirect field oriented controller) are
modeled with as much detail as possible. In the averaged model, the model of the
inverter switches is replaced by the averaged model.
Figure 1 and Figure 2 show the ISG and Indirect Rotor Flux Oriented
Controller schematics. |
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Simulation results (bus
voltage, current in/out of the ISG, and the shaft torque) for the detailed
and averaged ISG models are shown in Figure 3 and Figure 4, respectively.
As seen from the
figures, there is no difference between the simulation results other than
ripples in the detailed method. However, simulation time for the averaged model is much faster than the
detailed one. |
