# Electromechanical Energy Conversion

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## Questions

What do we do when we are finished with the draft and ready to publish?

• If it's been approved by the reviewers, move it to the articles section

Does anybody know of a way to put a box around text or math equations? Would I just have to create a 1x1 table?

## Announcements

If anyone wants to write the derivation of Ampere's Law you can put it on my (Wesley Brown) Ampere's Law page and be a co-author.

## Article Suggestions or Homework

1. Rewrite the notes for the wiki. (Really, this will help get ready for the exam. The professor who did them is the one who is writing the exam questions.)
• Effects of the Non-Linear B-H Curve
1. Draw and explain the effect of the non-linear B-H curve on current waveforms for a voltage excited inductor. (This is mostly done in the notes.)
2. Explain how to measure the B-H curve experimentally.
3. If the B-H curve was traced out more quickly in the experiment above, would the curve look different? If so why?
4. Show how to calculate the core losses of a nonlinear inductor using its i-v curve.
• Transformers
1. Explore transformers with more than one secondary winding.
• What is the input impedance of an idea transformer with two secondaries, one with N2 turns and one with N3 turns, each with a different load resistor on attached.
• How do the mutual impedances relate to the turns ratios in transformers with more than one secondary?
• Develop a circuit model for a non-ideal transformer with multiple secondaries. (Follow the way we did it in class. You will have more mutual inductances. You may or may not be able to do it by using ideal transformers, but you should be able to do it with mutual impedances for sure.)
2. Develop the theory of auto-transformers.
• Come up with an ideal transformer model for auto-transformers.
• Which part of the windings carries more current?
• Is there any isolation with auto-transformers?
• What if you have more than one tap on the auto-transformer? Can you come up with a model for that?
• Develop a circuit model for a single tap auto-transformer.
3. Explore how leakage flux affects the inductance of an inductor. What if that flux is then recovered and the effect accounted for by mutual inductance? Does the result agree with the simple calculation of inductance without leakage?
4. Describe the coupling factor, k, used in Spice simulators and other circuit simulators. Relate it to the leakage, magnetizing, and mutual inductances.
5. Derive the $Y/\Delta$ transformations.
6. Explore the voltage regulation $(V_{full ~load} - V_{no ~load} ) \over {V_{full ~load} }$x 100% as a function of the power factor angle on the load of a transformer. (You will note some surprising results in some cases.)
7. Describe the open circuit and short circuit test as applied to transformers.
8. Explore how much flux is in the core of a loaded ideal transformer.
• Three Phase Circuits
1. Calculate and compare how much power can be delivered with three phase circuits as compared to a single phase circuits. Assume that the same amount of copper is available for the transmission lines of both systems.
2. Compare and contrast the types of three phase transformers. (See the class handout.) Explain why each is better or worse in each situation.
• Explain what the big deal is with third harmonic currents in three phase transformers. Where do they come from? Why does the delta winding minimize their effect on voltage distortion?

And if you don't understand any of the above, please see the teacher! He is willing to sit down with you and work any and/or all of the above.

## Shaker Generator Project

### Links to useful things on the web

1. Design Project Handout
2. Shakemote
3. Magnet Powered Flashlight
4. An electromagnetic, vibration-powered generator for intelligent sensor systems
5. MAX1724 DC to DC converter
6. Magnetic Field on the axis of a cylinder
7. Magnetic Field from a cylindrical magnet or solenoid
8. A whole book, "Solenoids, electromagnets and electromagnetic windings," by Charles Reginald Underhill
9. Magnet Supplier
1. Demagnetization Curves
2. Pull or Push Force: Go to the magnet you like on K & J Magnetics, click on "Techincal" and there is a link to a curve generator that shows the force as a function of distance. Kudos to Will for noticing this!
3. B Field lines: Go to th magnet you like on http://kjmagnetics.com/proddetail.asp?prod=D3X0 K & J Magnetics], click on "Technical" and there is a link there to the flux lines for your magnet. This will help you get a better estimate of the voltage you will get from your generator. Note that only the z component of the B will add into the flux integral.
4. Magnetic Units Conversion
10. Biot Savart Law
11. Copper wire data (turns per inch, resistance per foot, etc.)
12. Coil Bobbin Supplier
13. Linear Technologies Energy Harvesting Regulators It looks like these devices may allow us to relax the requirement of at least 1.5 volts, down to about 500 mV. This may make it possible to fit in the box. I think this is an ideal application for a clamp circuit which will allow this device to work with an AC voltage input.

## References Used by the Professor

1. Our text, by Mohan.
1. I used the chapter on transformers and magnetic circuits.
2. I did NOT use the chapter on synchronous machines. See the references below for that.
3. I did NOT use much on three phase. See the references below for that.
2. Notes from Rod Heisler's Class
3. Magnetic Circuits
4. Transformer Model
5. Transformer notes and some problems
6. Notes from a Transformer Lecture in Sydney
7. Three Phase Power
8. Three Phase (written for Tradesmen)
9. Generator Animations
10. The class handout on three phase transformer types from Glenn Masden.
11. Harmonics in Transformers
12. Synchronous Machines
13. Notes on Induction Motors
14. An Application Note on Induction Motors
15. Some Questions Relevant to EMEC.
16. DC Motor Model for Control Matlab or Octave Script for this problem.
17. Textbook problem 6.13 Octave Script
18. DC Machines Powerpoint
19. Great Motor Animations
20. More Great Motor Animations
21. Real World Practical Motor Resource
22. More Real World Practical Motors

## Draft Articles

These articles are not ready for reading and error checking. They are listed so people will not simultaneously write about similar topics.

## Reviewed Articles

These articles have been reviewed and submitted.