Rockwell Automation 2364F Regenerative DC Bus Supply Unit (RGU) - Manual (Page 24)

Publication 2364F-5.01– October 2003
1-8 Overview
Regenerating Operation
As a secondary function, the RGU can convert DC power back into
AC line power in a process known as “regeneration”.
To regenerate, the RGU switches the IGBTs (shown in Figure 1.2) on
and off in a determined sequence to produce a series of pulses. These
pulses are varied in width to produce a 3-phase AC voltage with a
nearly-sinusoidal 3-phase AC current. By controlling the magnitude
and phase angle of the generated 3-phase voltage, the RGU can
control the power flow from the DC bus to the AC line.
During regeneration, the RGU:
• monitors the phase angle of the line voltage
• uses its own phase-lock loop algorithm to track the AC line
frequency
• generates a 3-phase voltage with a controlled magnitude and
phase angle
Figure 1.4 shows the AC line voltage to neutral and AC line current
waveforms of a regenerating RGU.
Figure 1.4
3-Phase AC Line Voltage and AC Line Current of a Regenerating RGU at Unity
Power Factor
V
line
To Neutral
I
line