Rockwell Automation 2364F Regenerative DC Bus Supply Unit (RGU) - Manual (Page 23)

Publication 2364F-5.01– October 2003
Overview 1-7
Motoring Operation
While motoring, the RGU functions like a boost converter,
controlling the DC bus voltage at a level slightly higher than the peak
of the AC line voltage.
For motoring, 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 AC line to the DC bus (and the phase
angle of the AC line current with respect to line to neutral voltage).
During motoring, 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 1.3 shows the AC line voltage to neutral and AC line current
waveforms of a motoring RGU.
Figure 1.3
3-Phase AC Line Voltage and AC Line Current of a Motoring RGU
Note: Actual current and line voltage will have some ripple.
V
line
To Neutral
I
line