1 / 56

DC Permanent Magnet Motors A tutorial winch design

DC Permanent Magnet Motors A tutorial winch design. David Giandomenico Lynbrook High School Robotics FIRST Team #846 DGiandomenico@lynbrookrobotics.com (408)343-1183. 2010 Breakaway. 2004 FIRST Frenzy: Raising the Bar. What We Want. Weight: Distance: Time (speed):. 130 lbs 1.5 feet

verdad
Download Presentation

DC Permanent Magnet Motors A tutorial winch design

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DC Permanent Magnet MotorsA tutorial winch design David Giandomenico Lynbrook High School Robotics FIRST Team #846 DGiandomenico@lynbrookrobotics.com (408)343-1183 David Giandomenico - FIRST #846

  2. 2010 Breakaway David Giandomenico - FIRST #846

  3. 2004 FIRST Frenzy: Raising the Bar David Giandomenico - FIRST #846

  4. What We Want. • Weight: • Distance: • Time (speed): 130 lbs 1.5 feet 5 seconds David Giandomenico - FIRST #846

  5. What We’ve Got:Some of the Motors supplied in FIRST Robotics Kit David Giandomenico - FIRST #846

  6. Kit Motors – Which One? 2013 choices (partial list!) All Data at 12VDC David Giandomenico - FIRST #846

  7. Motors - Sorted by Power David Giandomenico - FIRST #846

  8. “CIM” Motor Specification David Giandomenico - FIRST #846

  9. “CIM” Motor Performance David Giandomenico - FIRST #846

  10. No Load Speed No Load Current Stall Torque “CIM” Motor Performance Stall Current David Giandomenico - FIRST #846

  11. Current Limits (fuse)on Motor Power Stall Current 40 AFuse Limit ~100 Oz-In David Giandomenico - FIRST #846

  12. Choosing a motor based onMaximum Output Power • Calculate Energy required to lift load. • Given the Time & Energy, calculate the mechanical Power required. • Boost Power requirement to adjust for Friction in the gearbox and elsewhere. • Choose a motor whose Maximum Output Power is at least 4/3 * (safety margin) David Giandomenico - FIRST #846

  13. www.johnsonmotor.com David Giandomenico - FIRST #846

  14. David Giandomenico - FIRST #846

  15. Motor Selection David Giandomenico - FIRST #846

  16. What is Torque? But isn’t that “Work?” David Giandomenico - FIRST #846

  17. Units of Work vs. Torque • Work (Energy) • Torque ft-lbf, Joules (=N-m), KWh, … pound feet(lbf-ft), ft-lbf, oz-in, N-m … David Giandomenico - FIRST #846

  18. Work in a Rotating System Force T r David Giandomenico - FIRST #846

  19. Power, Torque & Speed David Giandomenico - FIRST #846

  20. Where is Max Power? Fisher Price Motor 2011 V=12VDC (speed,torque) From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  21. Maximum Power Fisher Price Motor 2011 V=12VDC From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  22. Standardize through Normalization http://www.mabuchi-motor.co.jp http://www.johnsonmotor.com David Giandomenico - FIRST #846

  23. Simplified through Standardization http://www.mabuchi-motor.co.jp http://www.johnsonmotor.com David Giandomenico - FIRST #846

  24. V=Rated Voltage 85%+15%=100% 50%+50%=100% 30%+70%=100% David Giandomenico - FIRST #846 From FIRST_MOTOR_CALC.xls

  25. Speed & Torque in a DC PM Motor • Let ={0,100%} such that David Giandomenico - FIRST #846

  26. Speed & Torque in a DC PM Motor Or, w/o calculus, Max occurs between two roots of quadratic, at =0, =1 that is, =½ or equivalently, when =50% Using calculus, Max Power occurs when: David Giandomenico - FIRST #846

  27. Max Power in a DC PM Motor David Giandomenico - FIRST #846

  28. V=Rated Voltage 75% David Giandomenico - FIRST #846 From FIRST_MOTOR_CALC.xls

  29. 2011 Fisher Price Motor All Data at 12VDC David Giandomenico - FIRST #846

  30. Fisher Price Motor 2011 V=12VDC From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  31. Fisher Price Motor 2011 V=12VDC Current rises linearly with Torque From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  32. Motor Current Where α is the % No Load speed David Giandomenico - FIRST #846

  33. Electrical Power David Giandomenico - FIRST #846

  34. Fisher Price Motor 2011 V=12VDC Input power is Current X Voltage From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  35. Fisher Price Motor 2011 V=12VDC From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  36. Fisher Price Motor 2011 V=12VDC From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  37. Fisher Price Motor 2011 V=12VDC From FIRST_MOTOR_CALC.xls David Giandomenico - FIRST #846

  38. Fisher Price Motor 2011 V=12VDC David Giandomenico - FIRST #846 From FIRST_MOTOR_CALC.xls

  39. Normalized Efficiency for IDEAL motor David Giandomenico - FIRST #846

  40. Max Efficiency Operating Point: Efficiency: David Giandomenico - FIRST #846

  41. Derivation of: Max Efficiency Efficiency: Where: Find Maximum : ...simplifying yields: Use Quadratic Formula to find roots: David Giandomenico - FIRST #846

  42. Derivation of: Max Efficiency continued Substitute for (1-α) to get: David Giandomenico - FIRST #846

  43. DC PM Motor Summary • Max Power occurs at 50% No-Load Speed • Best efficiency typically occurs at about 80%-93% No-Load Speed • Most DC PM Motors will overheat if operated continuously at speeds less than 50% when full voltage is applied. David Giandomenico - FIRST #846

  44. Gear Loss Estimate Suppose we have n=3 inline sets of gears, each with a 4:1reduction. What is the total efficiency if each gear set loses 4%? T = in or T = (100%-4%)3= 88.5% David Giandomenico - FIRST #846

  45. When x is small, David Giandomenico - FIRST #846

  46. Estimate of how many gear sets. • Suppose we want a gear reduction of 1200. How many gear sets with a reduction of 3 do we need? • Solve 3N = 1200 • N = ln(1200)/ln(3) = 6.45 David Giandomenico - FIRST #846

  47. Gear loss estimate We need 6.45 3:1 gear sets. Assuming a loss of 5% for each gear set, T = in or T = (1-5%)6.45= 71.8% David Giandomenico - FIRST #846

  48. Putting it all together • Choose a winch drum size • Calculate the drum rpm • Choose the % motor operating speed • Calculate the required gear reduction to operate at that speed • Verify the output winch line force meets or exceeds the original specification, including gear box losses David Giandomenico - FIRST #846

  49. Winch Design Specification David Giandomenico - FIRST #846

  50. Winch Drum Speed David Giandomenico - FIRST #846

More Related