Requires DC Generator, SCR or Other AC-DC Power Conversio

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Elevator DrivesPast, Present and Future

• As Presented
• at
• NAVTP Annual Forum
• Atlanta, Georgia
• May 3, 2007

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Elevator Drives - Discussion

• History
• Requirements
• Motor and Control Types
• Industry Trends
• Future Drives

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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

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Otis Patent 1861
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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

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Otis DC Elevator MotorCirca 1889
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History

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

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Otis No. 1 Geared DC Machine with DC Motor
Circa 1915
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Otis Gearless DC Machine
Circa 1919
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M-G Set Controls (Otis Elevator, 1920s)
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Otis Type 84 26 Broadway,NYC Circa 1930s
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History

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

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Otis type 84,NYC with Encoder
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Westinghouse 205 with Encoder
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History

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

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History

• Late 1990s

• 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

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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

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Elevator Drive Requirements
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Elevator Duty Cycle
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Four Quadrant Operation
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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

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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

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Elevators vs. Industrial Applications

• Quiet Operation
• Long Operating Life
• Long-Term Product Support

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Types of Motors

• DC Shunt Field
• High Speed Geared
• Low Speed Gearless
• Full HP Range 5 600 HP
• 8994 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

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Types of Motors

• AC Induction
• High Speed Geared, 275 HP
• Few Low Speed Designs for Gearless
• 8594 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

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Types of Motors

• AC Permanent Magnet (PM)
• New Designs for Compact Gearless Machines
• Torque Strength from Permanent Magnets
• 9095 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

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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

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Large DC Machines
Otis 72 and 269
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Types of Motor Drives

• 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

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Elevator Power Consumptionthe 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.

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Practical Energy Considerations

• Low Speed Elevators 50150 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

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Practical Energy Considerations

• Medium Speed Elevators 150450 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

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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

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Industry Trends

• Energy Consumption Reduction
• kW-hrs / Month
• Harmonics, Power Factor
• Performance
• Reduced FloorFloor Time
• Reduced Vibration
• Low Maintenance
• Cleanliness
• Larger PM Machines
• More Gearless Applications

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Energy Consumption

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

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Drive Type Comparison
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Drive Type Comparison
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Drive Type Comparison
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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

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Future Elevator Drives

• PWM-PWM Double Converter-Inverter

• Regulated Harmonics

• Unity pf

• Fully Regenerative

• Compatible with DC Stand-by Power

• PM Operation without Resolver
• Electronic Alignment Sensing
• Compact All Inclusive Packaging
• Works with AC Ind. or PM or DC Motors

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Worlds Tallest Buildings
Magnetek has Elevator Drives in 17 of the 30
tallest buildings in the world.