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VECTOR DRIVES. EASA June 2005 “REACHING NEW HEIGHTS” Dave Ruehle and Bill Colton. Outline. 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. Control Circuits
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VECTOR DRIVES EASA June 2005 “REACHING NEW HEIGHTS” Dave Ruehle and Bill Colton
Outline • 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 • Control Circuits • Ancillary devices • Couplings • Feedback • Parts and Pieces • Prime Mover • Mechanical Reduction(s)
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
How Vector Control is Achieved • Monitoring the feedback • Speed • Current • Back EMF • Comparing to Established Model • Adjust accordingly • Amount of Deviation • Motor/System Model
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 • 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 • 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 • 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 • Elevators • Hoists • Presses • Centrifuges • Unwind Stands • Windmills • Pumping Jack Drives • Application where Heated Resistors are a problem • Test Stands (dynamometers)