Transcript IMPULSE ® •VG+ Series 3 Theory of Operation IMPULSE ® Drive

Enabling Objective 1.3
Describe the Design of the Magnetek Impulse
VG+ series 3 Variable Frequency Drive
Controller
IMPULSE Drive
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IMPULSE Controls
Advantages
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Lowers Operating Costs and Minimizes Equipment
Downtime
– AC Squirrel Cage Induction Motors for Variable
Speed Control Provide Reliability
– Electronic Reversing, Multi-Speed Operation
Eliminates Conventional Magnetic Contactors
– Electronic Dynamic Braking Provides Effective
Braking without the Use of Mechanical Brakes
IMPULSE Drive
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IMPULSE Controls
Advantages
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Variable Speed Control w/Single-Speed Motor
Minimizes High-Starting Current w/Motor
Adjust Acceleration/Deceleration Rates
Unique Torque Limit Function
Creep Speed for Precise Positioning
without Plugging
Can Produce 150% Full Load Torque
IMPULSE Drive
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IMPULSE Controls
Advantages
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Inverter Output Frequencies >
60Hz are Possible
Retrofit Existing AC Equipment
• Motor Insulation class should be considered
IMPULSE Drive
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IMPULSE •VG+ Series 3
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Software Features
Brake Set Delay Timers
Ultra Lift™
Slip Compensation
Stall Prevention
Alternate Acceleration/Deceleration
Micro-Positioning Control™
Built-In Auto-Tuning
IMPULSE Drive
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IMPULSE •VG+ Series 3
Software Features
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Motor Torque Proving at Start
Roll Back Detection at Start
Seized Brake Detection at Start
Brake Proving at Stop
Torque Limited Load Check™
Torque Limited Accel and Decel
Built-In Auto-Tuning
IMPULSE Drive
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IMPULSE •VG+ Series 3
Software Features
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Quick Stop™
Reverse Plug Simulation™
Multi-Level Password
Motor Thermal Overload Protection
Motor Phase Loss Detection
Ground Fault Protection
Slack Cable Protection
IMPULSE Drive
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IMPULSE •VG+ Series 3
Software Features
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Overload/Load Check Counter
Number of Operations
Short Circuit Protection
Built-In Serial Communication
Fault History and Tracing via Flash ROM
Elapsed Run Timer
IMPULSE Drive
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IMPULSE •VG+ Series 3
Theory of Operation
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Closed Loop control via Encoder
Speed Set Points with Torque Limit
Determines Motor Slip
Calculates Torque Demand
Quick Response to Changes in Torque
Demand
IMPULSE Drive
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IMPULSE •VG+ Series 3
Theory of Operation
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Adjusts Torque Producing Current without
Increasing Magnetizing Current
In Simple Terms
• The VG+ series 3 controller is basically a 3
phase AC voltage to DC voltage to 3 phase
AC voltage converter.
• It starts by receiving 480Vac power and
utilizes a 3 phase rectifier to supply a DC bus.
IMPULSE Drive
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AC to Dc Conversion
AC
INPUT
DC BUS
• The DC bus is then applied to an Output
Transistor assembly to produce square wave
pulses. These pulses are modulated and
become additive to produce an output voltage
at the desired frequency and amplitude. A
basic bidirectional Inverter…
IMPULSE Drive
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DC to AC conversion
DC Bus
Gate Drive Board
IMPULSE Drive
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PWM Inverter
IMPULSE Drive
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PWM Inverter
IMPULSE Drive
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3-Phase PWM
IMPULSE Drive
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PWM Waveforms
Load Reactors
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Load Reactors (Coils) are utilized to protect the drive
unit from collapsing motor fields or short circuits and
they improve the efficiency by creating a more perfect
sine wave.
IMPULSE Drive
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Selecting Line/Load Reactors
Load Reactors
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Used on the Load Side of the AFD between AFD
and Motor
Protects the Drive under Motor Short Circuit
Conditions
Reactor Attempts to Recreate Perfect Sine Wave,
Improves Motor Efficiency
Use the Full Load Ampere Rating of the Motor
When Selecting Load Reactors
IMPULSE Drive
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IMPULSE •VG+ Series 3
Theory of Operation
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The Rectifier section of the Drive is energized
when power is applied to the crane and
remains so . When a drive signal is called
upon to start and run a motor, a 3 phase
output is developed and delivered to the
motor.
Flux Vector
“A Vector Drive uses feedback of various real world
information (encoder and CT’s) to further modify the
PWM pattern to maintain more precise control of the
desired operating parameter, be it current, speed or
torque. Using a more powerful and faster
microprocessor, it uses the feedback information to
calculate the exact vector of voltage and frequency to
attain the goal. In a true closed loop fashion, it goes
on to constantly update that vector to maintain it. It
tells the motor what to do, then checks to see if it did
it, then changes its command to correct for any
error.”
Flux Vector
“A true closed Loop Vector Drive can also make an
AC motor develop continuous full torque at zero
speed. This makes them suitable for crane and hoist
applications where the motor must produce full
torque before the brake is released or else the load
begins dropping and it can't be stopped. Closed Loop
is also so close to being a servo drive that some
people use them as such. The shaft encoder can be
used to provide precise travel feedback by counting
pulses”
IMPULSE Drive
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Flux Vector Control Typical
IMPULSE Drive
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Light Load
IMPULSE Drive
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Heavy Load
Dynamic Braking
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When slowing down of stopping a motor, Dynamic
Braking is utilized. Dynamic Braking occurs when the
applied frequency/voltage delivered to the stator is
lowered. Due to inertia, the rotor speed can now be
faster than the delivered stator speed which results in
the motor becoming a generator. Since Generated
Voltage is proportional to Speed “N”(differential or
slip) times the Magnetic Flux “O” a voltage is now
delivered back through the inverter section to the DC
bus.
Eg = Ofield X Ndifferential
Dynamic Braking
• A Dynamic Braking Unit is connected across
the +/- DC bus and this acts to dissipate the
energy and limit the rise of DC voltage.
– Without the Dynamic Braking resistor, damage
would occur to the drive unit.
With Dynamic Braking
IMPULSE Drive
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V/F Ratio
IMPULSE Drive
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V/F Curve
IMPULSE Drive
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Torque & Horsepower vs. Speed
IMPULSE Drive
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Theoretical V/F Ratio w/Voltage Boost
IMPULSE Drive
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Encoder Specifications
• Heavy Duty Industrial Type
• Output Resolution – 1,024 Pulses
per Revolution
• 12V DC Differential Line Driver Output
• Connected to Motor Shaft to Provide
Zero Backlash
• Shielded Cable
IMPULSE Drive
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IMPULSE•VG+ Series 3 PG-T2 Board
IMPULSE Drive
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PG-X2 Card Inputs/Test Points
IMPULSE Drive
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IMPULSE •VG+ Series 3
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Start-Up Procedure
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Check Programming Parameters •
Check Encoder Connections
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Confirm Rotation of Motor
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Initial Inspection
Auto Tune Motor
Take No-Load Reading
Load Test
Check Brake Proving
Save Parameters
IMPULSE Drive
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Selecting Line/Load Reactors
Line Reactors
• Acts as a Current Limiting Device
• Filters the Waveform and Attenuates
Electrical Noise Associated with
AFD Output
• Use Continuous Output Rating of the