Copyright © 2008 Rockwell Automation, Inc. All rights reserved. Direct-to-Drive Technology Product...

Copyright © 2008 Rockwell Automation, Inc. All rights reserved.

Direct-to-Drive Technology

Product Feature Overview

PowerFlex 7000 MV Drive

Control BoardsIdentical line and machine side control boards used for asynchronous and synchronous drives.• Floating point Digital Signal Processors (DSP).• Field Programmable Gate Arrays (FPGA) used for advanced logic.• External I/O with 16 digital inputs and 16 digital outputs.

Operator interface terminal with 16-line, 40-character LCD display for easy set-up, monitoring andtroubleshooting.

Robust AC/DC power supplies withoptional redundancy.

Low voltage swing out tub for access to cable connection assembly and motor filter capacitor Rugged DC link inductor

limits fault current and eliminates nuisance trips.

A compact enclosure saves on valuable floor space. Rear access not required

6.5 kV SGCT power semiconductorsreduce parts count and increase reliability.

Integral cooling fan provides efficient heat transfer from power components.

PowerCage modules on the rectifier and inverter reduce manufacturing time and allow easy access to main power components for quick replacement.

6-Pulse, 18-Pulse, or PWM rectifiers available as standardfor greater flexibility in meeting power quality needs.

Common gate drive power supply module reduces parts count and lowers overall cost

Copyright © 2008 Rockwell Automation, Inc. All rights reserved. 3

Introduction

Why buy a Drive Isolation Transformer if you don’t need one?

The PowerFlex 7000 with Direct-to-Drive technology allows you to:

– connect utility power directly to the drive without an isolation transformer and

– connect a new or existing motor directly to the drive, eliminating unnecessary motor filtering


Why Drives Use Isolation Transformers


Why Use an Isolation Transformer?

Harmonic Cancellation

Medium Voltage Drive Manufactures traditionally use multi-winding isolation transformers to mitigate unwanted harmonics by phase shifting the transformer secondary windings.

An 18 Pulse Drive mitigates harmonics to low levels through it’s three 20 degree phase shitted secondary windings


Why Use an Isolation Transformer?

Common Mode Voltage Protection

Manufacturers also use transformers to protect motors from Common Mode Voltage stress.


Direct-to-Drive Technology is a Better Solution


Direct-to-Drive: The Better Solution

The Direct-to-Drive Active Front End rectifier uses semi-conductor switching to reduce line current harmonics to levels that comply to the worlds most accepted harmonic standards.

The Active Front End uses switching and Selective Harmonic Elimination to reduce harmonics.

Harmonic Cancellation



Motor line-to-ground voltage(2kV/div)

4160 Volt - Motor line and neutral to ground voltages at full speed/load

Motor neutral-to-ground voltage (200V/div)


Direct-to-Drive technology produces almost no common mode voltage so it is suitable for new or existing motors and imposes no voltage stress at the drive input.



• DV/DT and Reflected Wave• And, in addition to mitigating Common Mode Voltage, Direct-to-Drive

technology does not generate dv/dt or Reflected Wave Voltage Stress on Motors or on the Utility.

Current

Voltage

Line Side Motor Side


The Advantages of Direct-to-Drive Technology


The Advantages of Direct-to-Drive

• Lower Total Cost of Ownership• The simplicity Direct-to-Drive technology results in a lower

initial capital investment, lower operating cost, lower installation cost and lower maintenance cost relative to drives that require isolation transformers:

• No isolation transformer cost,• No extra motor insulation,• No special line cable insulation,• No special motor cable

insulation,• No shipping splits,• No transformer protection

relay,

• No dv/dt, sine filter or motor terminator,

• No power factor correction required,• No harmonic filtering required,• No transformer losses,• No transformer air conditioning,


The Advantages of Direct-to-Drive

2400 mm (94.5 inches)

DIRECT-TO-DRIVE

4160Volt 1000 HPPowerFlex 7000 with Direct-to-Drive

2950 kg (6500 lbs)

• Reduced Size and Weight• The PowerFlex 7000 with Direct-to-Drive technology is typically smaller and lighter

that drive technologies that use Isolation Transformers.

2400 mm (94.5 inches)

DIRECT-TO-DRIVE

4160Volt 1000 HPPowerFlex 7000 with Direct-to-Drive

2950 kg (6500 lbs)


What is Direct-to-Drive Technology?



Direct-to-Drive technology is the combination of three innovations that allow the PowerFlex 7000 to operate without an isolation transformer on both new and existing motors: – The SGCT– The Active Front End Rectifier and – Common Mode Voltage Protection



The SGCT

The SGCTs high voltage rating and ability to be connected in series, allow the PowerFlex 7000 to be rated up to 6600 volts without adding complexity.The gentle switching characteristics of the SGCT make dv/dt and reflected wave motor filtering unnecessary.

SGCT Symmetrical Gate Commutated Thyristor (SGCT)

• SGCT blocks voltage in forward & reverse directions up to 6500V, current flow in 1 direction only

• Non-Punch-Through structure• Symmetrical pnp transistor in the wafer• Significant advantages

– Simplification or elimination of snubber components

– operation at a higher switching frequency, hence reducing the size of passive components (by 50%) and improving performance of the drive

– reduction of component count, hence improving reliability, cost, and size of the drive

MV Drive Topology Comparison

PowerFlex 7000 PWM •SGCT inverter switch•Low component count•Simple power structure

VSI-PWM 3 Level •IGCT or MV IGBT inverter switch•Medium component count•Power structure complex due to series and parallel diodes required for 3 level

VSI-PWM Multi-Level (Series Cell) •LV IGBT inverter switch•Very high component count. •Very Complex power structure and transformer configuration

Simple

Complex

Very Complex

Patented* Power Cage

• Houses main power components

• Compact, modular package

• Common design for rectifier & inverter modules

Easy to Service

• Front access • Component

replacement in less than 5 minutes

• no special tools required



The Active Front End Rectifier

To comply with IEEE 519 while avoiding the use of a phase shifting isolation transformer, the PowerFlex 7000 with Direct-to-Drive technology employs the Active Front End Rectifier.The active font end uses the SGCT to produce a PWM switching pattern that prevents the drive from producing high levels of line harmonics.



The Active Front End Rectifier

Harmonic Spectrum for the Active Front End:

5th7th

11th13th

17th19th

23rd25th

AFE

18P

12P

6P0

5

10

15

20

25

AFE

18P

12P

6P




Common Mode Voltage Protection technology, provides an alternative to using an isolation transformer. This technology is designed to mitigate common mode voltage stress generated by variable frequency drives.This feature does not require a motor with extra insulation and does not require an isolation transformer.

M

CM

VP

CM

VP


In Summary

The three innovations that define Direct-to-Drive technology allow the PowerFlex 7000 to function with new or existing motors without an isolation transformer:

• The SGCT• The Active Front End Rectifier• Common Mode Voltage Protection

The result is a smaller, lighter drive that has the lowest total cost of ownership on the market.

Copyright © 2008 Rockwell Automation, Inc. All rights reserved. Direct-to-Drive Technology Product...

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