Automotive Alternator Charging a Battery

This example shows how alternator behavior can be abstracted to a DC model that simulates efficiently. This test harness first ramps the alternator speed linearly from zero to a typical idle speed of 900 RPM. When the generated voltage is sufficient to overcome the forward voltage drop associated with the rectifier diodes, the battery charging current starts to ramp up. The test harness then ramps up the speed to 5000 RPM, and the alternator has to back off the field voltage to maintain the regulated voltage. The model captures the increase in stator resistance as the alternator heats up, this reducing device performance

Model

Simulation Results from Simscape Logging

The plot below shows the behavior of the alternator as the engine speed varies.

Results from Real-Time Simulation

This example has been tested on a Speedgoat Performance real-time target machine with an Intel® 3.5 GHz i7 multi-core CPU. This model can run in real time with a step size of 50 microseconds.