Chapter 1 introduction to automotive electrical and electronic system

University of Technical Education Ho Chi Minh City INTRODUCTION TO AUTOMOTIVE ELECTRICAL AND ELECTRONIC SYSTEMS Le Thanh Phuc Faculty of Automotive Engineering Email: thanhphucckd@gmail.com Automotive electrical and electronic systems Main systems Starting Charging Ignition Lighting and signal Information Engine control Automotive control Air conditioning Accessories Components of a circuit Series Circuits Series Circuits •A series circuit has only one path for current That means current is the same through every part of the circuit • If any part of the circuit is broken or disconnected, the whole circuit will stop working •No current is present in a series circuit unless there is continuity through the entire circuit •You can use Ohm's Law to predict the behavior of electricity in a circuit Voltage Drops in a Series Circuits Parallel Circuits Parallel Circuits A parallel circuit has these key features: • Total current equals the sum of the branch currents • Resistance of each branch determines the current through each branch • If the branch resistances are the same, branch currents will be the same • If the branch resistances are different, the current in each branch will be different • The voltage drop across each load resistance is the same This is because the source voltage is applied equally to each branch • The equivalent resistance of the circuit is less than the smallest branch resistance Circuit Connection Electrical Symbols Wiring Diagram Inductors A Simple Electromagnet A simple electromagnet can be made from a length of wire, a battery, and a nail Depending on the size of the battery, this circuit might require some added resistance to keep excess current from burning the wire Voltage Generated by Induction When a current flowing through a coil is cut off, the collapsing magnetic field generates a voltage spike Ignition Coil An ignition coil takes advantage of the collapsing magnetic field to generate a high voltage pulse for the spark plugs Relay Relays are used throughout the automobile Relays which come in assorted sizes, ratings, and applications, are used as remote control switches Relay A relay uses an electromagnetic coil to move a set of contacts Relay