Introduction to Engineering Electronics

1
Lecture 10 Magnetic Levitation

• IEE Culminating Lab
• Timely Curricular Information

2
Magnetic Levitation Experiment

• Magnets or magnetic materials can be suspended
  either using magnetic attraction or repulsion and
  permanent or electromagnets.

3
Magnetic Levitation

• Trains can magnetically fly over a roadbed with
  position sustained by some kind of control system
• Force can either be attractive or repulsive

4
Some Commercial Products
http//www.gadgets4sure.com
5
The Physics of Levitron

• The spinning top keeps itself stabilized
  vertically while the magnetic base keeps the top
  suspended.
• http//www.levitron.com/

6
The Physics of Levitron

• The top actually precesses around the vertical
  axis (like the earth on its axis).
• There is a range of stable revolutions per second
  (20-30). The weight must also be set to exactly
  balance gravity.

7
2 Minute Quiz

• Specify any design issue for repulsive levitation
• Specify any design issue for attractive
  levitation

8
Maglev Experiment How the Globes Are Suspended
Electromagnet
IR Emitter
Control Circuit
IR Detector
IR Light Beam
Ball to be suspended

• From Barrys Coilgun Design Site
• Barrys design is slightly more advanced
• http//www.oz.net/coilgun/levitation/home.htm

9
Maglev Experiment

• Close up photos showing levitation of washer and
  ball bearing with magnet attached. Some preferred
  orientation is necessary for stability.

10
Maglev Experiment

• The position of the suspended object (here a
  ball) is sensed by how much of an IR beam is
  blocked by the object.
• This requires an IR emitter and an IR detector.

11
Maglev Experiment

• The emitter puts out a constant light intensity.
• The detector signal is amplified and compared
  with a reference voltage.
• The output of the comparison drives the
  electromagnet.
• If the ball is too high (detected IR signal too
  small), the coil current is reduced.
• If the ball is too low (detected IR signal too
  large), the coil current is increased.

12
Maglev Experiment
From Radio Shack Mini-Notebooks

• The IR emitter and detector are powered just like
  the LEDs we used previously. The resistor in
  series gives us the best operation and also
  protects the diode.
• Lab 2 on Diodes has the resistor.
• Labs 5, 6, and 7 drive the LEDs directly.

13
Maglev Experiment

• The photo emitter and detector circuits to be
  used in the experiment

14
Maglev Experiment
Inverting Op-amp
Buffer

• The circuit is constructed of the op-amp
  configurations we saw in Lab 4.
• The actual circuit must also contain some
  mathematical operation for stable control.
• This control in this case is analog. There are
  many other options.

15
Maglev Experiment
Inverting Op-amp
Buffer

• For the inverting op-amp
• For the buffer

16
Maglev Experiment
From Detector
Buffer
Buffer

• First, two buffer circuits are used to isolate
  the control function (which we will return to).

17
Maglev Experiment
Bias Buffered Input to Summing Inverting Op-amp
Inverting Op-amp
18
Maglev Experiment

• Voltage from op-amps drives transistor which
  provides the current for the electromagnet.

19
Maglev Experiment
Control

• How does the control work?
• We need to look at different types of control.

20
Maglev Types of Control
Oven Temp Set Point Temp Power

• On-Off Control (also called Bang-Bang)
• Commonly used for thermostats. When the
  temperature is to low (bang) it is on. When the
  temperature is too high (bang) it is off.
• Note the large excursions in temperature and that
  hysteresis is used to delay turn on and turn off.

21
Maglev Types of Control
Set Point Temp
Oven Temp For 3 gains

• Proportional Control
• The power W is proportional to the difference in
  temperature between the set point and the actual
  temperature. Note as gain increases, the
  temperature becomes more unstable but can get
  closer to the set point.

22
Maglev Types of Control
Oven Temp Set Point Temp Power

• Proportional-Integral-Differential Control (PID)
• Works the best but is more mathematically
  demanding since it is 3rd order.

23
Maglev Types of Control

• Proportional-Integral Control (PI) In a simple
  system where noise may be a problem, the
  derivative term is not used. This is the approach
  used in the Embedded Control Class.
• More on control can be found at Feedback and
  Temperature Control from the University of Exeter
  and the Hackers Diet (really!) by John Walker.

24
Maglev Experiment Controller
In
Out

• For a resistor
• For a capacitor

25
Controllers

• PID Controllers can be implemented many, many
  different ways.
• Analog input can be converted to digital and then
  processed in the digital domain before being
  converted back to analog to drive the coil.
• Digital circuitry can be used.
• A microcontroller (like in Embedded Control) can
  be programmed
• Other options may be discussed in the next
  lecture.

26
Some Registration Week Information on Majors
Related to IEE

• Electrical Engineering
• Computer and Systems Engineering
• Electric Power Engineering
• EE/CSE Dual Degree
• EE/EPE Dual Degree
• CSE/CS Dual Degree
• EE/Applied Physics Dual Degree

27
ECSE Undergraduate Advisor

• David Nichols Available for advice any time
  Monday, Wednesday and mornings on Thursday. (JEC
  6002)
• Email Nichols_at_ecse.rpi.edu

28
Electrical Engineering
Science, Math, HSS Core
ECSE Core
Engineering Core
EE Core
Concentration
Restricted Electives
Free Electives
29
Electrical Engineering
Science, Math, HSS Core
Engineering Core

• Chem Mat I
• Calculus III
• Differential Eqns
• Physics III
• CS I
• HSS (5) PD II
• Applied Math Elective

• IEA
• IEE
• EGCAD
• IED
• Embedded Control
• PD IIII
• Multidisciplinary Elective

30
Electrical Engineering
EE Core
ECSE Core

• Electric Circuits
• Computer Components and Operations
• Signals Systems
• Probability for Engr. Applications

• Analog Electronics or Digital Electronics
• Fields and Waves I
• Microelectronics Technology
• Lab Elective

31
Electrical Engineering
Concentration
Specified Electives

• Automatic Controls
• Comm Info Proc
• Computer Hardware
• Electromagnetics
• Electronic Circuits
• Power Electronics
• Manufacturing or Entrepreneurship
• Microelectronics
• Individualized

• Lab Elective
• Design Elective (no longer included in
  concentration)

32
Electrical Engineering
Free Electives
Restricted Electives

• Any course at all
• Usually used up for dual degrees
• Most students take additional technical courses
• See undergrad handbook

• Any ECSE or EPOW
• Used to satisfy concentration
• Can also include one ENGR course

33
Computer and Systems Engineering
Science, Math, HSS Core
ECSE Core
Engineering Core
CSE Core
Concentration
Restricted Electives
Free Electives
34
Computer and Systems Engineering
Science, Math, HSS Core
Engineering Core

• Chem Mat I
• Calculus III
• Differential Eqns.
• Physics III
• CS III
• Data Structures Alg.
• HSS (5) PD II
• Applied Math Elective

• IEA
• IEE
• EGCAD
• IED
• Embedded Control
• PD IIII
• Multidisciplinary Elective

35
Computer and Systems Engineering
CSE Core
ECSE Core

• Electric Circuits
• Computer Components and Operations
• Signals Systems
• Probability for Engr. Applications

• Computer Architecture, Networks and Operating
  Systems
• Software Engineering Elective

36
Computer and Systems Engineering
Concentration
Specified Electives

• Automatic Controls
• Comm Info Proc
• Computer Hardware
• Computer Systems
• Manufacturing or Entrepreneurship
• Individualized

• Software Engineering Elective
• Design Elective (no longer included in
  concentration)

37
Computer and Systems Engineering
Free Electives
Restricted Electives

• Any course at all
• Usually used up for dual degrees
• Most students take additional technical courses
• See undergrad handbook

• Any ECSE or CSCI
• Used to satisfy concentration
• Can also include one ENGR course

38
Electric Power Engineering
Science, Math, HSS Core
ECSE Core
Engineering Core
EPE Core
Concentration
Restricted Electives
Free Electives
39
Electric Power Engineering
Science, Math, HSS Core
Engineering Core

• IEA
• Engr. Proc. Or IEE
• EGCAD
• IED
• MAU
• Modeling Control of Dynamic Systems
• Embedded Control
• Electronic Instrumentation
• PD IIII
• Thermal Fluids Engr.
• Multidisciplinary Elective

• Chem Mat III
• Calculus III
• Differential Eqns
• Physics III
• C Prog. For Engineers
• HSS (5) PD II

40
Electric Power Engineering
EPE Core
ECSE Core

• Electric Circuits
• Fields Waves I
• Signals Systems

• Power Engineering Fundamentals
• Electromechanics
• Semiconductor Power Electronics
• EPE Lab
• EPE Design

41
Electric Power Engineering
Concentration
Specified Electives

• Not required for EPE degree
• Optional Concentration in Power Electronics
  Systems -- Includes courses from EPOW, ECSE,
  MANE

• Technical Elective any course in Engineering or
  Science above the 2000 level

42
Electric Power Engineering
Free Electives

• Any course at all
• Usually used up for dual degrees
• Most students take additional technical courses
• See undergrad handbook

43
Dual Degrees

• EE/CSE Includes only the CSE concentrations
  (130 credits)
• CSE/CSYS Includes all CSE concentrations (131
  credits)

• EE/EPE Includes only the Power Electronics
  concentration (131 credits)
• EE/Applied Physics Includes only the
  Microelectronics concentration (132 credits)

44
Recent Changes

• Check ECSE webpage during registration period
• New Undergraduate Handbook
• New design course options
• ECSE Design
• Control Systems Design
• Other courses will be changing
• Please check advising information on a regular
  basis