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Author Topic: Ejs Open Source Direct Current Electrical Motor Model Java Applet ( DC Motor )  (Read 9005 times)
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ahmedelshfie
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on: April 28, 2010, 02:08:26 am » posted from:,,Brazil

Ejs Open Source DC Motor Model by Fu-Kwun Hwang and lookang
Modified interface by Ahmed
Original project Ejs Open Source Direct Current Electrical Motor Model Java Applet ( DC Motor )

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Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
  • Please feel free to post your ideas about how to use the simulation for better teaching and learning.
  • Post questions to be asked to help students to think, to explore.
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Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!


* Dcmotor.gif (27.68 KB, 900x662 - viewed 788 times.)
« Last Edit: April 28, 2010, 02:11:16 am by ahmedelshfie » Logged
ahmedelshfie
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Reply #1 on: April 28, 2010, 02:14:21 am » posted from:,,Brazil

Video youtube about Ejs Open Source Direct Current Electrical Motor Model Java Applet ( DC Motor )    Smiley
http://www.youtube.com/watch?v=t4qBcVSyVT0&feature=player_embedded
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ahmedelshfie
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Reply #2 on: April 28, 2010, 02:29:13 am » posted from:,,Brazil

O level Syllabus
This helps students learn
explain how a current-carrying coil in a magnetic field experiences a turning effect and that the effect is increased by increasing
(i) the number of turns on the coil,
(ii) the current
discuss how this turning effect is used in the action of an electric motor
describe the action of a split-ring commutator in a two-pole, single-coil motor and the effect of winding the coil on to a soft-iron cylinder


Exercises:
The external magnetic field Bz can be varied using the slider Bz. When Bz is positive, it is in the direction vertically up. Vary Bz until it is negative, what is the direction of the Bz then?
The current comes from the battery higher potential end and travels in a wire forming a closed circuit and travels back to the lower potential end of the battery. When θ = 0o current flows from the battery higher potential end, to the top brush, to the RED split ring, through the coil loop in order ABCD, back to BLUE split ring, bottom brush and lower potential end of the battery. What is the direction of the current flow in wire AB? What is the direction of the current flow in wire CD? using Fleming's left-hand rule, deduce the relative directions of force acting on i) AB ii) CD iii) BC iv) DA. hint: note that Fmag = I*B*L*sin(I&B) may be useful.
By taking moments about the axle PQ, consider the forces on AB and CD, deduce the direction of the torque and the motion if the coil loop was initially at rest (ω = 0 deg/s). Select the suitable sliders of your choice and verify your hypothesis for 2 angles. Discuss with your partner what you have discovered. Ask your teacher if there are any problem/issues faced using this virtual lab.
Explain and show the equations involving T ( in earlier part of question), why the forces on wire BC and DA did not contribute to the calculation of rotating torque about axle PQ?
By considering the forces in the x direction for wire BC and DA, suggest what can happen to the coil loop if the forces are large enough. Suggest why it does not happen in terms of the properties of the wires in the coil loop.
Explain how a current-carrying coil in a magnetic field experiences a turning effect and that the effect is increased by increasing (i) the number of turns on the coil, (ii) the current (iii) increasing the magnitude of the external Bz field
After conducting some inquiry learning on the virtual DC motor model discuss how this turning effect is used in allowing the coil loop to rotate. You may right-click within a plot, and select "Open EJS Model" from the pop-up menu to examine the model equations of the motion. You must, of course, have EJS installed on your computer.
Describe the action of a split-ring commutator in a two-pole magnet setup, single-coil motor. Suggest the effect adding a soft-iron cylinder in the winding the coil.

Advanced Learner:
Please submit your remix model that model features that are not available in the existing virtual lab and share your model with the world through NTNUJAVA Virtual Physics Laboratory http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=28.0. Impacting the world with your model today!
« Last Edit: May 17, 2010, 05:21:09 am by ahmedelshfie » Logged
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Reply #3 on: April 28, 2010, 02:30:45 am » posted from:,,Brazil

This is a derived work to help students understanding DC motors especially the split ring purposes. Thanks to Fu-Kwun Hwang for his original codes! here http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=912.0

Changes made
1 made n =3 to simplify the number of currents to eyeball
2 added battery wires brush + sign to give context of power of DC motor
3 mask a part of the coil to give the illusion of single coil instead of plane previously
4 design the focus to be on just the 2 sides of the coil which has the most force that powered the rotation of DC motor
5 created animated gif as well for wikipedia.com i hope
6 added angle cta from 0 to 360 ^o to give sense of orientation
7 added omega for degree/s
8 added alpha for degre/s^2
9 added logic for split ring angle cta1 and cta2 to provide the ctadoubledot only when the is contact with split ring
10 equation of motion to reflect the no contact part to be without the torque from the magnetic force
11 magnetic force on and off when contact on and off
12 force shown
13 added particles for battery side wires which the particles motion is always from + potential so some code need to be re-purposed.
14 n is 5 now, better look and feel
15 motion of particles on battery wires now stop if there is no closed loop of the electric circuit
16 motion of particles current and electron are correctly reflected after extensive learning and debugging
17 added current can be negative
18 redesigned the angular acceleration and force activation condition into 4 quadrants, divide and conquer, previous original model is without the split ring consideration/model
19 added texts PQ axle, ABCD coil contact XY for ease of verbalization of communicating ideas and hypothesis for learners
20 added description and exercises to complement the virtual lab
21 rectified a major design mistake which i created due to misinterpretation of the usage of variable "sign" and finally got it to work (move) in correct representation/convention even with electron particles by designing with my own logic of how it can be made to do the simulation according to my understanding of the physics involved.
22 created a new logic for negative current in the battery wire to reflect the convention adopted today in physics
23 made the split ring commutator rotate with the coil instead of the original stationary design to conform to textbook explanation and the flash animation below
20March 2010 thanks to Taha Mzoughi http://physci.kennesaw.edu/mzoughi/bio.shtm remixed model, i realized what enhancements can be done.
24 added Torque clockwise positive view from the default perspective
25 Added Inertia to demonstrate the difficulty in increasing the angular velocity over time
26 added step button to allow for closer observation by learners

other reference:
http://www.magnet.fsu.edu/education/tutorials/java/dcmotor/index.html
http://www.walter-fendt.de/ph11e/electricmotor.htm


This data from topic http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1266




By Lookang wee
« Last Edit: May 17, 2010, 05:21:36 am by ahmedelshfie » Logged
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Reply #4 on: April 28, 2010, 02:35:02 am » posted from:,,Brazil

Two carbon brushes are made to press lightly against the commutators.
The motor features a external magnet (called the stator because it’s fixed in place) and an turning coil of wire called an armature ( rotor or coil, because it rotates). The armature, carrying current provided by the battery, is an electromagnet, because a current-carrying wire generates a magnetic field; invisible magnetic field lines are circulating all around the wire of the armature.
The key to producing motion is positioning the electromagnet within the magnetic field of the permanent magnet (its field runs from its (top) south to (bottom) north poles). The armature experiences a force described by the left hand rule. This interplay of magnetic fields and moving charged particles (the electrons in the current) results in the magnetic force (depicted by the green arrows) that makes the armature spin because of the torque. Use the slider current I to see what happens when the flow of current is reversed. The checkbox current flow & electron flow alows different visualization since I = d(Q)/dt and Q= number of charge*e. The Play & Pause button allows freezing the 3D view for visualizing these forces, for checking for consistency with the left hand rule .
A swing back and fro motion (maybe θ = 0o to 180o and 0o) is all you would get out of this motor if it weren't for the split-ring commutator — the circular metal device split into parts (shown here in red and blue with a gap of β1 and β2) that connects the armature to the circuit. Electricity flows from the positive terminal of the battery through the circuit, passes through a copper brush to the commutator, then to the armature.
When the current is positive, current runs through ABCD as shown in the diagram (select the checkbox labels?), a +y direction force would act on AB. An -y direction force would act on CD. Taking moments about the axle, reveals a resultant torque T = Fmag*AD*cosθ acts on the coil loop. The coil loop rotates in an clockwise manner (view from battery side) until it reaches the θ = 80o position (assuming that split ring angle are default at β1 = -80o and β2 = 80o). At this θ = 80+o position, the current is cut off. However, the momentum of the loop carries it past the horizontal position until the coil loop reaches θ = 110o position. Contact between loop and split ring commutator is established again and the current in the coil loop is now reversed. A -y direction force now acts on AB while a +y direction force acts on CD. The rotation motion is reinforced clockwise (view from battery side) as θ continues to rotate from 110o to 260o. At this θ = 260+o position, the current is cut off. However, the momentum of the loop carries it past the horizontal position until the coil loop reaches θ = 280o position. Contact between loop and split ring commutator is established again and the current in the coil loop is now reversed back to same as from θ = 280o to 80o. A a +y direction force would act on AB. An -y direction force would act on CD and the loop reaches θ = 0o . The cycle repeats after θ = 0o allowing the armature to experience torque in the reinforced direction at the right time to keep it spinning.
The purpose of the commutator is to reverses the direction of the current in the loop ABCD for every half a cycle.
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