Linear Induction Motor Electrical and Computer Engineering Tyler Berchtold, Mason Biernat and Tim Zastawny Project Advisor: Professor Steven Gutschlag 4/21/2016
2 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
3 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
4 Alternating Current Induction Machines • Most common AC machine in industry • Produces magnetic fields in an infinite loop of rotary motion • Current-carrying coils create a rotating magnetic field • Stator wrapped around rotor [1] [2]
5 Rotary To Linear [3]
6 Linear Induction Motor Background • Alternating Current (AC) electric motor • Powered by a three phase voltage scheme • Force and motion are produced by a linearly moving magnetic field • Used in industry for linear motion and to turn large diameter wheels [4]
7 Project Overview • Design, construct, and test a linear induction motor (LIM) • Powered by a three-phase voltage input • Rotate a simulated linear track and cannot exceed 1,200 RPM • Monitor speed, output power, and input frequency • Controllable output speed [5]
8 Initial Design Process • Linear to Rotary Model • 0.4572 [m] diameter 𝑀 = 𝛴𝑠 (1.1) • 0.3048 [m] arbitrary stator length • Stator contour designed for a small air gap • Arc length determined from stator length and diameter • Converted arc length from a linear motor to the circumference of a rotary motor • Used rotary equations to [6] determine required frequency and verify number of poles
9 Rotational to Linear Speed (1.2) (1.3)
10 10 Pole Pitch and Speed (1.4) • For fixed length stator τ = L/p • L = Arc Length τ A B C A B C [7]
11 11 Linear Synchronous Speed Ideal Linear Synchronous Speed vs. Frequency 45 2-Pole Machine (stator length 0.3048m) Output Synchronous Speed [m/s] 40 4-Pole Machine (stator length 0.3048m) 35 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Frequency [Hz] [8]
12 12 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
13 13 Variable Frequency Drive • VFD • 0-10V signal correlates to 0-120 Hz • A/D Converter • Onboard the ATmega128 • 250 ms interrupt service routine • Resolution is 0-5V • D/A Converter • External chip • Provides 0-10V reference signal to VFD to control output frequency [9]
14 14 System Block Diagram D/A Analog 0-10V Freqeuncy Variable Drive Atmega 128 Start/ Stop 0-10V Signal Microctonroller A/D Analog 0-10V [10]
15 15 Tachometer Subsystem • Main Components • Photo-interruptor • Transparent Disk with Notches • External Interrupt • Counts pulses • 4 pulses per rotation • 250 ms interrupt service routine [11]
16 16 LCD Subsystem • LCD Displayed Values • RPM • Calculation to obtain RPM • Convert to string • Input string to LCD • Output frequency • Calculation to obtain VFD output frequency • Convert to string • Input string to LCD
17 17 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
18 18 Initial Design • 3-phase, 2-Pole machine • Salient pole arrangement • Operating at a max frequency of 120 [Hz] • 18” (0.4572 [m]) diameter track • Desired 12” (0.3048 [m]) length for the stator • Max rotational speed of 1200 [RPM] corresponding to a max linear speed of 28.72 [m/s] A B C A B C [12]
19 19 Rotational to Linear Speed Ideal Linear Synchronous Speed vs. Frequency 45 2-Pole Machine (stator length 0.3048m) Output Synchronous Speed [m/s] 40 4-Pole Machine (stator length 0.3048m) 35 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Frequency [Hz] [13]
20 20 Rotational to Linear Speed Ideal Linear Synchronous Speed vs. Frequency 45 2-Pole Machine (stator length 0.3048m) Output Synchronous Speed [m/s] 40 4-Pole Machine (stator length 0.4542m) 35 30 25 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Frequency [Hz] [14]
21 21 Turns Per Phase 𝑸 𝒑𝒗𝒖 𝑼 𝒒𝒊 = (1.5) 𝟕. 𝟕𝟕{𝒒𝒐 𝒏𝒕 𝑪 𝒃𝒉 𝑩 𝒒 𝒍 𝒙 𝑱 𝒒𝒊 𝜽 𝑸𝑮 ൟ
22 22 Previous Data TABLE I: PREVIOUS DATA FROM MAGNETIC LEVITATION SENIOR PROJECT Rotational Speed (RPM) Output Power [W] 1106 510.78 1343 619.16 [15] [16]
23 23 Final Design • 4-Pole machine • Salient pole arrangement • Laminated stator segments • Operating at a max frequency of 120 [Hz] • 16 AWG with current rating of 3.7 [A] • Stator Tooth Length of 3.5” (0.0889 [m]) • Mounting holes on stator • Theoretical 213 turns per stator tooth • Achieved 235 turns per tooth
24 24 Wiring Diagram S N S N S N S N S N N S [17]
25 25 Insulated Bobbins • Glass cloth tape used between the stator teeth and coils • Electrical tape used at ends to secure glass cloth tape • Necessary to prevent shorting between copper coils and the stator core • Plastic pieces in stator slots to further prevent shorting [18]
26 26 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
27 27 Bill of Material TABLE II: BILL OF MATERIAL Component Supplier Price Quantity Total Price Laminated Stator Core Laser Laminations $375 1 $375 2,000 ft. Dipped Copper Wire Illinois Switchboard $176 1 $176 Scotch Glass Cloth Tape Grainger $11.55 5 $57.75 Scotch Vinyl Electrical Tape Grainger $8.95 3 $26.85 Power First Cable Tie Bag (100) Grainger $13.95 2 $27.90 3/8" 6" Steel Bolts Ace Hardware $3.20 6 $19.20 3/8" 6" Steel Bolts Ace Hardware $1.49 2 $2.98 3/8" Nuts Ace Hardware $0.30 24 $7.20 Angle Irons Ace Hardware $13.99 1 $13.99 $706.87
28 28 Outline of Presentation • Background and Project Overview • Microcontroller System • Final Design • Economic Analysis • Hardware • State of Work Completed • Conclusion
29 29 Completed Stator • Manufactured by Laser Laminations [19]
Simulated Linear Track 30 30 Mounting Solution • Using previous mounting hardware used with new base mounting • Smaller air-gap then anticipated was achieved • Under 1/8” air -gap [20]
Simulated Linear Track 31 31 Mounting Solution Con’t • 6 Inch fully threaded steel hex bolts • Allow for fine adjustment of wheel height • Wheel mounting was raised 1- 9/16” • Put bolts through all linear track mounting parts to prevent bending of bolts on angled components [21]
32 32 Stator Mounting Solution • Angle irons used to hold bottom mounting holes of stator to base • 11/32” bolts used in both base and stator mounting [22]
33 33 General Mounting • All parts sand blasted to remove rust and previous paints • Spray painted grey for uniform color and rust prevention • Washers used with mounting hardware [23]
34 34 Issues with Mounting • Initial stator mounting holes from stator to base were off • Required re-drilling of mounting holes • Simulated linear track is not perfectly balanced • Changed the screws holding the copper on simulated linear track to prevent coil interference [24]
35 35 Linear Track Run-off TABLE III: Total Run-off of Simulated Linear Track Side (+) Run-off (-) Run-off Total Run-off + 0.015” - 0.015” 0.03” Right + 0.016” - 0.013” 0.029” Middle - 0.012” 0.03” Left + 0.018 [25]
36 36 Coil Materials Used • 16 AWG Wire • GP/MR-200 Magnet Wire/ Winding Wire • Heat is rated at 210C by wire • Wire diameter calculated when determining turns per phase and stator tooth width • 0.418” of gap between adjacent coils [26]
37 37 Mock Stator Tooth • Created a mock wood stator tooth • Grooves in base to hold zip-ties • Wrapped brass around tooth • Increase size • Allows for coil to be moved on stator easier [27]
38 38 Winding Coils • Created a replica stator tooth for winding coil on • Initially used a slow lathe for windings coils • Approximately 2 hours to create one coil • Issues with layer quality [28]
39 39 Winding Coils • Changed to a different lathe • Benefits included higher quality wraps • Increase in speed • Only 30 Minutes to complete a coil [29]
40 40 Winding Methods and Changes • Drilled a hole into base of wooden tooth for more secure winding start • Added a layer of Teflon on each coil layer • Wrapped outsides of coils with glass cloth tape for protection and extra support [30] [31]
41 41 Issues with Winding and Coils • Wires crossing back accidently in layers • Losing tension in wrapping • Results in slinky effect • Coils when tightened down collapse [32] [33]
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