Transcript VECTOR DRIVES - NASA Infrared Telescope Facility

VECTOR DRIVES
EASA June 2005
“REACHING NEW HEIGHTS”
Dave Ruehle and Bill Colton
Outline
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Define a Drive
What is an Inverter Drive
Why the Vector was Invented
How Does a Vector Work
What Types of Vectors Exist
Typical Applications for Vector Drives
What is a Drive
• Parts and Pieces
 Prime Mover
 Mechanical Reduction(s)
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Control Circuits
Ancillary devices
 Couplings
 Feedback
What is an Inverter
Drive
• Terminology
Scalar Drive
VFD
ASD
VVVF
VFI
What is an Inverter
Drive
• Speed Control Device
Controls STATOR frequency
Rotor changes speed with load
• Speed Changes dependant on motor slip
• NOT a current controller
Only a current limiter
Why the Vector was
Invented
• Increase Application Efficiency
Better Speed Control
Better Torque and/or Force Control
More Efficient Use of Power
Why the Vector was
Invented
• Performance Benefits
Rotor Speed Regulation
Lower Rotor Inertia Requirements
Much Wider Speed Ranges
Torque (or Force) Control
Zero Speed Full Torque
How Inverter Control Is
Achieved
• Convert AC Input to DC
• Filter the DC Power
• Create a digital output pulse train varying the
frequency and voltage to Stator
How Vector Control is
Achieved
• Establish the motor/system Model
Stator Resistance
Stator Inductance
Rotor Resistance
Rotor Inductance
Air gap Losses
Machine Losses and Inertia
How Vector Control is
Achieved
• This is achieved in several fashions
Manual – Programming Each Item
Auto Tuning
• Program Basics
• Run Tests for Additional Items
Adaptive Tuning
• Continuously Adjusting for Changing
Conditions
• Now The System Model is Established
How Vector Control is
Achieved
• Hardware
Comparison
Components Inverter Vector
Converter
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Filter
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Output
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Feedback
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How Vector Control is
Achieved
• Monitoring the feedback
Speed
Current
Back EMF
• Comparing to Established Model
• Adjust accordingly
Amount of Deviation
Motor/System Model
How Vector Control is
Achieved Speed Changes
What Types of Vectors
Exist
• Open Loop (Encoderless) Vector
Establishes the Shaft Position from the current
(amp) measurement
Advantages
• Lower Initial Cost
• Reduced Wiring
Disadvantages
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Not as responsive
Limited Speed Range
Difficulty with Impact Loads
Temperature Changes can be Problematic
What Types of Vectors
Exist
• Closed Loop Vector
Monitors Shaft Position via Feedback
• Encoder
• Resolver
Advantages
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Excellent Speed Regulation
Full Torque at Zero Speed
Systems Capabilities
Very Responsive
Higher Safety
Easier to Tune
What Types of Vectors
Exist
• Closed Loop Vectors (Cont.)
Disadvantages
• Additional Initial Cost
• More Wiring
• Motor Length
• Requires Better Wiring Practice
What Types of Vectors
Exist
• Space Vector
A method of firing transistor to control a
specific element
• Current Feedback
• Voltage Feedback
• Hysteresis
• Sine Triggered (Coded) Vector
A method of firing transistors to control the
sine wave
Applications for Vector
Drives
• Extruders
Closed Loop for Clamped Dies
Open Loop for Continuous Feed
• Lifts
Closed Loop for Safety
Has been done with Open Loop and
Mechanical Load Brakes – consult
manufacturers
Applications for Vector
Drives
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Bridge Drives – Typically Scalar
Trolley Drives – Typically Scalar
Conveyors – Typically Scalar
Centrifugal Loads – Typically Scalar
Potential Energy Savings with Encoderless
• Spindle Drives – Typically Closed Loop
Rapid Response Times
Accurate Speed for Tapping
Controlled Grind Speed
Applications for Vector
Drives
• Winders
Typically Closed Loop for Tension Control
• Mooring Winch – Encoderless
• Mixers – Typically Scalar
• Line Shaft Replacements – Closed
Loop with “electronic line shaft”
capability
• Cut to Length – Closed Loop with
Motion Control
Applications for Vector
Drives
• Flying Shear – Closed Loop with
Motion Controller
• Stacker Cranes
Horizontal (X) – Scaler or Closed Loop
Elevation (Y) – Closed Loop for Safety
Bins or Forks (Z) – Scaler or Closed Loop
• Crushers
Oversized Scaler
Applications for Vector
Drives
• Types of Braking
D.C. Injection
Shunt Braking – Most Common
Bus Sharing
Line Regenerative
Line Regenerative
Applications
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Elevators
Hoists
Presses
Centrifuges
Unwind Stands
Windmills
Pumping Jack Drives
Application where Heated Resistors are a
problem
• Test Stands (dynamometers)