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