Allen-Bradley PowerFlex 7000

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18 Rockwell Automation Publication 7000-UM202D-EN-P - May 2018

Chapter 1 PowerFlex 7000 Drive Overview

18-pulse Rectifier with Separate Isolation Transformer

For high power constant torque applications and/or when the line voltage is

higher than the motor voltage, a transformer is required for voltage matching

(indoor and outdoor transformer options are available). The 18-pulse rectifier

uses SCRs instead of the SGCTs used for an AFE rectifier. When used for high

power constant torque applications, the 18-pulse rectifier has lower losses than

the AFE rectifier, making 18-pulse ideal for the highest power requirements.

The 18-pulse isolation transformer provides the required input impedance and

addresses common mode voltage just like the separate isolation transformer

used with the AFE rectifier. However, instead of a PWM rectifier switching

pattern and a single rectifier bridge, the 18-pulse configuration mitigates line

side harmonics through harmonic current cancellation in the isolation

transformer phase shifted secondary windings. The inverter is the same

configuration for all available rectifier options.

Figure 4 - 3300/4160V 18-pulse Rectifier with Separate Isolation Transformer

Cooling Technology

These VFDs are supplied with heatsinks for most configurations and heatpipes

for the highest-power AFE configurations. While both configurations draw

heat away from the semiconductors, heatpipes are bigger, more efficient, and

require larger fans and airflow.

Information and graphics in this manual show both configurations.

LINE CONVERTER

L- M-

DC LINK

L+ M+

MACHINE CONVERTER

U (T1)

V (T2)

W (T3)

4U (Z1)

4V (Z2)

4W (Z3)

ISTX

SCRs

3U (Y1)

3V (Y2)

3W (Y3)

2U (X1)

2V (X2)

2W (X3)

SGCTs