Linear Induction Motor (LIMO) Modular Test Bed for Various Applications University of Connecticut Department of Electrical and Computer Engineering Advanced Power Electronics and Electric Drives Lab (APEDL) Team Members: David Hackney (EE), Jonathan Rarey (EE), Julio Yela (EE) Advisor: Professor Ali Bazzi Date 04/25/2014 1
Outline Introduction Applications Advantages Design vs. Simulation Budget Timeline Questions 2
What really is a LIM? Can be conceptualized as a conventional rotating machine which has been cut Flatten out the rotary machine and now rotational motion is effectively linear motion Source: www.force.co.uk 3
Design Goals High degree of modularity Interchangeable rotors (material and design testing) Application specific rotor guides Variable stator designs and adjustable air gap One or two stators for position control Variable frequency drive (VFD) interfaced with LabVIEW for speed and force control Integration of sensors in stator for position and temperature monitoring Production design is supplemented by simulations to optimize potential future designs 4
Applications Extremely diverse but for the purposes of this design include: High speed trains Sawing Aircraft launching Machine learning Commercial applications include but are not limited to: Industrial robots Laser cutting machines PCB assembly Wafer etch machines MRI & X ray equipment Source: http://www.ga.com/magnerail 5
Advantages Main advantages of the proposed system: Rotor and stator modularity (in both material and design) Air-gap adjustability Position control Application specific rotors Test bed for linear machine research Conventional Advantages of LIM s: Production of direct thrust without converting rotational energy into translational energy Adjustable speed Inexpensive maintenance cost Increased reliability (no need of bearings) Source: http://www.baldor.com/products/linear_motors.asp 6
Design Flowchart Extensive Literature Review Preliminary Design ANSYS Simulation Stator/Rotor Design Factors Stator/Tooth/Rotor Parameters Fabrication Tech Services Material/ Windings Simulation Optimization Assembly Future Work Fabrication Testing & LabVIEW Control Integration Testing & LabVIEW Control Integration Preliminary Test Bed Optimized Linear Induction Test Bed 7
Machine Design Design Parameters Phases 3 Power and reduce force ripple Poles 4 Optimal speed Slots 24 Integer winding factor Slots Per Pole Per Phase 2 Integer winding factor Stator Length 36.75 cm Design choice Stator Width 6 cm Design choice Stator Material M19 Steel C5 coated Low core loss and availability Lamination Stacking Depth 5 cm Design choice Stator Lamination Thickness 26 gauge Standard thickness Coil Pitch Full Pitch Ease of winding Stator Tooth Shape Rectangular Slot Literature research Rotor Dimensions 36 x 6 x ¼ Design choice Rotor Material Aluminum Cost effective 8
Stator Coil Winding Original stators (left) built with 20 turns per coil Testing showed this to be insufficient and 80 turns was achieved through use of a winding jig 9
Stator Coil Winding Original method (left) produced coils requiring hand forming Revamped method (right) produced drop-in quality and significantly reduced winding time 10
System Assembly (SolidWorks) 11
High Level System Overview VFDs control stators moving rotor LabVIEW communicates with VFDs and MCU Encoder feeds back to MCU http://www.yaskawa.com http://www.usdigital.com 12
Variable Frequency Drive (VFD) VFD input voltage: 3-phase 208 V 60 Hz Power : 2.2 kw VFD Output Freq. Range: 0-500 Hz Force-Vector Control Modbus TCP interface Source: http://www.yaskawa.com/site/home.nsf/home/home.html 13
VFD LabVIEW Control Controls unit in velocity mode (V/Hz Control) Force and position control to be available upon completion Monitors VFD parameters and position Built in safety limits on torque and power Communicates with VFDs, Encoder interface, and NI DAQ for tracking motor temperatures 14
Linear Encoder Used in conjunction with VFD s to enable force control. Encoder module sends signals to VFD s which uses those values to improve force tracking. LabVIEW communicates with an encoder interface which reports back position, which is used in position control modes and is used in other safety features. Scale used is 120 LPI resolution. Source: http://www.usdigital.com/products/em1 15
Encoder Integration Yaskawa VFDs do not have position control or tracking Atmel controller was programmed to interface with the encoder pulse pattern, track position and send data to LabVIEW GUI Feedback rate of 1000 Hz used, 16 bit position register Higher feedback rates can be achieved at the risk of consuming more processor time from other LabVIEW tasks http://digital.ni.com
Encoder Interface PCB Reprogrammable Atmega328P Controller, TTL serial enabled, optional external clock (20 MHz), PWM controlled RGB LED, Encoder power control 9-v power source stepped down by 5-v regulator
FEA Using ANSYS Maxwell Finite element analysis (FEA) determines how to optimize the current production design Optimized parameters include: Stator tooth design, stacking depth, fill factor and rotor dimensions Experienced significant software license issues with ANSYS Maxwell (University now in talks to purchase licenses) 18
ANSYS Maxwell Design 19
Simulations Locked Rotor Comparison of ¼ inch aluminum rotor at: 800 A*turns (top) 200 A*turns (bottom) 20
Ohmic Loss Aluminum Rotor 800 A*turns Total Ohmic Loss in the rotor is 4.03W 21
Animation of Magnetic Field 22
Animation of Flux Lines 23
Animation of Current Density 24
Budget 2 Yaskawa A1000 VFD s ~ $2,000.00 Stator Laminations $888.80 TufQUIN TFT Insulation Paper $46.00 Aluminum Rotor < $50.00 Rotor Guides < $100.00 4000 ft 18 AWG Magnet Wire < $205.58 Rail System Parts $568.49 Tech Services < $1000.00 Sensors & Electronics $245.40 Interface Boards < $200.00 Total: < $5,304.27 25
Timeline September October November December January February March April May 2011 Induction Machine Research VFD and Control Research CAD Designs Design & Simulation Sensor Research GUI Design & Control Testing Assembly Machine Optimization Application Integration and Testing Tasks emerging from last semester 26
Questions 27