The Direct Current (DC) Electric Motor

What you need to know:-Electromagnetism- main parts of the motor-Flow of electricity through the motor- interaction of opposing magnetic fields

Starting Motor Fundamentals

• An automobile uses many DC motors in various systems. The main application of a DC motor is the engines starter motor.

What the starter motor does:• Converts electrical energy from the battery to

mechanical energy to crank the engine• Produces a turning force through the interaction

of magnetic fields inside the motor

Magnetic Field Action

• Made up of invisible lines of force• Since like charges (fields) repel each other

and unlike charges (fields) attract each other, magnetic fields can produce motion

Magnetic Field Action

Simple Electric MotorIf a current-carrying winding is placed inside a magnetic field, the winding rotates away from

the pole shoes

Commutator and Brushes

• Keep a motor turning by controlling the current through the windings

• Together, they serve as a sliding contact between battery power and the windings

Commutator and Brushes

Commutator reverses the electrical

connection when the loop rotates around

Increasing Motor Power

• Several loops of wire and a commutator with many segments are used to increase motor power

• As the motor spins, many windings contribute to the motion

Armature

• Supports the windings• Iron core increases the strength of each

winding’s magnetic field

Field Windings

• Stationary insulated wire wrapped in a circular shape around iron pole shoes

• When current flows, a magnetic field builds• This field acts against the armature’s field,

producing motion

Armature andField Windings

Know this diagram and be able to label these parts

This is a cutaway view of a starter motor.

The Starter Motor Circuit

• A short video on the automobiles starter motor circuit.

Principles_Of_Starting.mp4

The DC Motor Principle

• A Short video explaining the interaction of magnetic fields between the armature and field coils.

DC_Motor_Principle_1.flv

What to Know for the Exam

• For the exam you will need to know:• 1. basic components: armature, pole

shoes/field coils, commutator, brushes, solenoid

• 2. Be able to explain the basic dc motor principle….how magnetism is formed, and how opposing magnetic poles create rotation in the motor.