November 13, 2014

ENGR B47Introduction to Engineering & DesignWeek #12

Electrical Motors(And Analysis and Technical Writing)

Very Brief Overview

• Build a motor

• Quantify its performance

• Write a manual for its use

Basics of Magnetism

[walk-through on whiteboard]

• Permanent magnets– Likes repel– Opposites attract– Draw “field lines” represent this behavior

• Electromagnets– Relationship between current & magnetic field– Straight wires and loops

Building a Motor (Conceptually)

[walk-through on whiteboard]

• Permanent magnets– Two fixed on the outside– One rotating in the center

• Can get a “motor” to work for half a rotation

• “Flip a switch” and change the magnet?

Building a Motor (Conceptually)

What would it look like?

Graphics from pcbheaven.comhttp://www.pcbheaven.com/wikipages/How_DC_Motors_Work/

Graphics from pcbheaven.comhttp://www.pcbheaven.com/wikipages/How_DC_Motors_Work/

How Can We Make That Happen?

Graphics from pcbheaven.comhttp://www.pcbheaven.com/wikipages/How_DC_Motors_Work/

Graphics from pcbheaven.comhttp://www.pcbheaven.com/wikipages/How_DC_Motors_Work/

Motor Project Goals

• Construct a motor• Characterize performance

(see worksheet on course website)– Speed vs. Torque curve– Power vs. Torque curve– Maximum Power calculation

• Create instruction manual– Audience is middle school students– Include assembly guide & component list– Step-by-step instructions (lots of pictures!)– Troubleshooting section

How Will Your Group Be Graded

Motor Project is 20% of final grade (see syllabus)

• Performance of motor [20%]– Mostly concerned that it works– Little incentive to out-perform other groups– Must produce graphs of curves

• Presentation [20%]• Instruction Manual [30%]• Peer Evaluation [30%]

To Do List for Today

• Form groups of 6 (randomized)• Exchange contact information• Delegate responsibilities to each member• Make schedule to accomplish all tasks• Start constructing motor