MATLAB Examples

Vehicle Electrical System

This example shows how to simulate the electrical system of a vehicle using Simulink® and Simscape™ Power Systems™.


Figure 1: The vehicle electrical system.

System Components

The system simulated consists of a few components. The main power source is the internal combustion (IC) engine which drives the shaft of the alternator. The alternator produces the AC power. The diode trio rectifies the AC current generated from the alternator to DC current which is applied to the alternator field. The indicator lamp lights when the system is turned on and the alternator is not producing power. The rectifier bridge converts the AC power into DC power. The smoothing capacitor, voltage sensor, battery, and vehicle loads are connected to the DC bus.

The alternator is a 3-phase synchronous machine with its field current regulated to give control over the DC bus voltage. This is simulated by using the Synchronous Machine Round Rotor model.

The 3-phase AC output of the alternator is fed into the 6-pulse rectifier bridge to give the DC voltage required to charge the car battery and to supply the balance of the electrical system of the car.

Operation of the System

When the IC engine is off, the battery supplies the current to the alternator field winding. The indicator lamp is turned on.

When the IC engine runs, the alternator will start to produce voltage and the diode trio will conduct and let the current flow to the alternator field winding. The indicator lamp is then turned off.

When the DC bus voltage reaches the upper voltage limit (i.e., 14.5 V in the model), the current flowing to the alternator field is bypassed. As a result, the DC bus voltage decreases. If it reaches the lower voltage limit (i.e., 13.5 V in the model), the diode trio is reconnected to the field winding.