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Elevator Drives Past, Present and Future

Elevator Drives Past, Present and Future. As Presented at NAVTP Annual Forum Atlanta, Georgia May 3, 2007. Elevator Drives - Discussion. History Requirements Motor and Control Types Industry Trends Future Drives. History. 236 BC – First Passenger Lift, Archimedes

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Elevator Drives Past, Present and Future

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  1. Elevator DrivesPast, Present and Future As Presented at NAVTP Annual Forum Atlanta, Georgia May 3, 2007

  2. Elevator Drives - Discussion • History • Requirements • Motor and Control Types • Industry Trends • Future Drives

  3. History • 236 BC – First Passenger Lift, Archimedes • 1853 – Safe Elevator Demo, Elisha Otis • 1857 – First Safe Elevator Installation, Cooper Union, NYC • 1861 – Otis Elevator Patent

  4. Otis Patent 1861

  5. History • 1873 – First Modern DC Motor • 1874 – J. W. Meaker Door Opener Patent • 1880 – First Electric Motor Controlled Elevator Siemens / Sprague • 1882-1889 – Tesla AC Induction Motor 3-Phase Squirrel Cage Design • 1889 – Otis Elevator Uses DC Motor

  6. Otis DC Elevator MotorCirca 1889

  7. History • 1891 – Ward Leonard Variable Speed Control • AC Induction Motor Turning DC Dynamo • Rheostat to Control Generated Voltage • DC Voltage Controls DC Motor Speed • 1900-1970’s – Ward-Leonard M-G Sets and DC Motors Used for Variable Speed Elevators • AC Motors Used 1 and 2 Speed Starters

  8. Otis No. 1 Geared DC Machine with DC Motor Circa 1915

  9. Otis Gearless DC Machine Circa 1919

  10. M-G Set Controls (Otis Elevator, 1920’s)

  11. Otis Type 84 26 Broadway,NYCCirca 1930’s

  12. History • 1975-Present • Thyristor (SCR) DC Drives Control Elevators • All Analog Components in the 70’s • Replaces Aging M-G Sets • 1980’s – Microprocessors Improve • Car Dispatch and Motor Drive Controllers

  13. Otis type 84,NYCwith Encoder

  14. Westinghouse #205 with Encoder

  15. History • Late 1980’s – • Variable Frequency Inverters AC Induction Motors, Geared Applications Only • Early 1990’s – • More AC Inverters and Motors Begin to Displace Small DC, 3-15 HP • Mid-1990’s – • Vector Control AC Inverters 10-40 HP Almost as Good as SCR-DC. • KONE Introduces PM EcoDisc AC Machine

  16. History • Late 1990’s – • Custom Gearless AC Induction Machines • First Fully Regenerative AC Elevator Drives • Much Discussion on PM-AC and MRL • SCR-DC Still Used for Medium and Large Building Mods

  17. History • 2000-Present – • More PM-AC Motor Manufacturers. PM Gearless Begins to Replace AC Geared • EU Focus on Efficiency and Harmonics/EMC • Lower Cost IGBT Inverter Components • North America Begins to Focus on Energy Reduction • New Construction Leaning toward AC • SCR-DC Still Used on Medium-Large Building Mods

  18. Elevator Drive Requirements

  19. Elevator Duty Cycle

  20. Four Quadrant Operation

  21. What Customers Want • Repeatable Elevator Performance • Smooth Operation • Reliable Operating Life • Effortless Installation • Custom Control Interface • High Efficiency • Conformance to All Codes • Low Installed Cost

  22. Elevators vs. Industrial Applications • Infinitely Variable Speed Range • Infinitely Variable Torque Range with Smooth Bump Less Operation • Millions of Repeated Operating Cycles with High Peak Torque • High Inertia Resonant Load • Accurate Stopping Position • Unattended Operation 24/7/365

  23. Elevators vs. Industrial Applications • Quiet Operation • Long Operating Life • Long-Term Product Support

  24. Types of Motors • DC Shunt Field • High Speed Geared • Low Speed Gearless • Full HP Range 5 – 600 HP • 89–94% Efficient • High Torque Capacity Accel/Decel • In Elevator Service for 70+ Years • Requires DC Generator, SCR or Other AC-DC Power Conversion from AC Utility Power • DC Motor Can Act Like a Generator

  25. Types of Motors • AC Induction • High Speed Geared, 2–75 HP • Few Low Speed Designs for Gearless • 85–94% Efficient • Many with Single or 2 Speed Starters • Can be Variable Speed by Inverter Control of Frequency • Torque Strength Derived from Out of Phase Excitation Current • Requires Flux Vector Control for Wide Operating Speed Range • Can Act Like a Generator

  26. Types of Motors • AC Permanent Magnet (PM) • New Designs for Compact Gearless Machines • Torque Strength from Permanent Magnets • 90–95% Efficient • Compatible with Inverters to Control Speed • Requires Synchronous Flux Vector / Angle Control to Regulate / Modulate Torque • Supply Limited to Specialty Machine Builders • Not Suitable for High rpm Speed Geared Designs • Can Act Like a Generator

  27. Modernization • Why keep a DC machine? • Many large DC machines cannot be easily replaced with AC. • Large Installed Base of DC Machines Worldwide • DC Motors and Machines are in Good Working Order and Provide Excellent Ride Quality

  28. Large DC Machines Otis 72 and 269

  29. For DC Motors M-G Set SCR-DC PWM-DC For AC Motors Variable Voltage V V V F Inv. (V/Hz) Open/Closed Loop Vector Control Inv. Open/Closed Loop Synchronous PM Inv. Closed Loop Regen or Non-Regen Types of Motor Drives

  30. Elevator Power Consumption…the need for Regeneration • Horsepower = Torque x Speed • Gearless Friction Losses are 10-20% of Elevator HP Rating • Moving inertia absorbs energy during acceleration that must be removed during deceleration. • Mechanical, electric and electronic losses are proportional to torque or current flow. • Energy Wasted / Dissipated During Deceleration = Heat • Excessive heat in control rooms must be removed.

  31. Practical Energy Considerations • Low Speed Elevators 50–150 fpm • Almost Always Geared… or PM Gearless • Low Speed Usually Means Low Power 2-35 HP / 2-25 kW • Most power is consumed by frictional losses. • True regeneration is not critical. • High Gearbox Losses During Regeneration • Drive type makes little difference in overall energy consumption. • If DC, Good Candidate for Conversion to AC by Replacing Motor • Low Installed Cost is Usual Critical Issue

  32. Practical Energy Considerations • Medium Speed Elevators 150–450 fpm • Geared and Some Gearless… Including PM • 15-60 HP / 12-45 kW • Lower Frictional Losses in Gearbox • Recovery of inertia energy becomes important, particularly with gearless. • Resistive Braking Still Possible but Need to Perform Heat Load Calculations for Equipment Room

  33. Practical Energy Considerations • High Speed Elevators 500-1,600+ fpm • Low Friction Gearless • 45-600 HP / 34-450 kW or Larger • True Regeneration is Mandatory

  34. Industry Trends • Energy Consumption Reduction • kW-hrs / Month • Harmonics, Power Factor • Performance • Reduced Floor–Floor Time • Reduced Vibration • Low Maintenance • Cleanliness • Larger PM Machines • More Gearless Applications

  35. Energy Consumption • Elevator Speed and Payload • Frequency of Use • Hoist Way Efficiency • Motor Efficiency • Power Conversion Efficiency • Idle Losses • Regeneration

  36. Drive Type Comparison

  37. Drive Type Comparison

  38. Drive Type Comparison

  39. Future Expectations • More PM Gearless • Low and High Power • More Interest in Energy Conservation • Overall Efficiency • Regeneration • More Restrictions on Harmonics and EMC • Sinusoidal High pf Utility Line Current • All Inclusive Drive Units with Filters

  40. Future Elevator Drives • PWM-PWM Double Converter-Inverter • PM Operation without Resolver • Electronic Alignment Sensing • Compact All Inclusive Packaging • Works with AC Ind. or PM or DC Motors • Regulated Harmonics • Unity pf • Fully Regenerative • Compatible with DC Stand-by Power

  41. World’s Tallest Buildings Magnetek has Elevator Drives in 17 of the 30 tallest buildings in the world.

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