Post on 23-Jan-2016
transcript
Enabling Objective 1.3
Describe the Design of the Magnetek Impulse VG+ series 3 Variable Frequency Drive
Controller
IMPULSE® Drive
IMPULSE® ControlsAdvantages
• 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
IMPULSE® ControlsAdvantages
• 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
IMPULSE® ControlsAdvantages
• Inverter Output Frequencies >
60Hz are Possible
• Retrofit Existing AC Equipment • Motor Insulation class should be considered
• Brake Set Delay Timers
• Ultra Lift™
• Slip Compensation
• Stall Prevention
• Alternate Acceleration/Deceleration
• Micro-Positioning Control™
• Built-In Auto-Tuning
IMPULSE®•VG+ Series 3
Software Features
IMPULSE® Drive
• 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®•VG+ Series 3
Software Features
IMPULSE® Drive
• Quick Stop™
• Reverse Plug Simulation™
• Multi-Level Password
• Motor Thermal Overload Protection
• Motor Phase Loss Detection
• Ground Fault Protection
• Slack Cable Protection
Software Features
IMPULSE®•VG+ Series 3
IMPULSE® Drive
• Overload/Load Check Counter
• Number of Operations
• Short Circuit Protection
• Built-In Serial Communication
• Fault History and Tracing via Flash ROM
• Elapsed Run Timer
Software Features
IMPULSE®•VG+ Series 3
IMPULSE® Drive
• 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®•VG+ Series 3
Theory of Operation
IMPULSE® Drive
• Adjusts Torque Producing Current without Increasing Magnetizing Current
IMPULSE®•VG+ Series 3
Theory of Operation
IMPULSE® Drive
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
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
DC to AC conversion
Gate Drive Board
DC Bus
IMPULSE® Drive
PWM Inverter
IMPULSE® Drive
PWM Inverter
IMPULSE® Drive
3-Phase PWM
IMPULSE® Drive
PWM Waveforms
Load Reactors
• 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
Selecting Line/Load ReactorsLoad Reactors
• 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
• 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.
IMPULSE®•VG+ Series 3
Theory of Operation
IMPULSE® Drive
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”
Flux Vector Control Typical
IMPULSE® Drive
Light Load
IMPULSE® Drive
Heavy Load
IMPULSE® Drive
Dynamic Braking
• 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
V/F Ratio
IMPULSE® Drive
V/F Curve
IMPULSE® Drive
Torque & Horsepower vs. Speed
IMPULSE® Drive
Theoretical V/F Ratio w/Voltage Boost
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
IMPULSE•VG+ Series 3 PG-T2 Board
IMPULSE® Drive
PG-X2 Card Inputs/Test Points
IMPULSE® Drive
• Initial Inspection
• Check Programming Parameters
• Check Encoder Connections
• Confirm Rotation of Motor
• Auto Tune Motor
Start-Up Procedure
IMPULSE®•VG+ Series 3
• Take No-Load Reading
• Load Test
• Check Brake Proving
• Save Parameters
IMPULSE® Drive
IMPULSE® Drive
Selecting Line/Load Reactors
• Acts as a Current Limiting Device
• Filters the Waveform and Attenuates Electrical Noise Associated with AFD Output
• Use Continuous Output Rating of the
Line Reactors