Reference Manual

Unit Description, PSU 1200 W
12.2 PSU DC
The PSU DC converts incoming voltage ranging from -39 V to
-72 V DC to the regulated DC voltage that is required.
12.2.1 Block Diagram
DC/DC
Output
Filter
Input Filter
Control and Supervision
Indi-
cators
Opto
Interface
DC
Input
DC
Output
P007805A
Control Alarm
Figure 78 PSU DC block diagram
The PSU DC consists of the following main units:
• Input filter (EMC filter)
• DC/DC Converter
• Output filter (EMC filter)
• Control and supervision circuits
Input Filter
The incoming voltage first passes through the input filter, where it is
filtered to prevent unwanted signals from being radiated from the PSU.
DC/DC Converter
A phase-shifted, full-bridge converter that converts the DC into a square
wave, which is then fed into the primary side of the transformer. The
converter limits the current in case of overload.
In the transformer, the voltage is converted to a 24 V AC square wave,
and this wave is rectified to DC through a diode rectifier.
The output provides constant power regulation, rather than the more
common current limited, and delivers 1200 W over the whole output
voltage range from 22 to 29 V.
Output Filter
Filters the output voltage is to prevent unwanted signals from being
radiated from the PSU.
148 (421)
EN/LZT 720 0008 R1A
2001-06-26
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