5
TMN/TMP SERIES
OPERATING MANUAL
inspection.
6.3
UNIPOWER Corporation will cooperate fully in case of any shipping
damage investigation.
6.4
Always save the packing materials for later use in shipping the unit.
Never ship the rectifier system without proper packing.
7.0
DESCRIPTION OF OPERATION
7.1
Block Diagram. A diagram of a TMN/TMP Series Module is shown in
Figure 2. The AC input first goes through a Class B EMI filter then to a
full-wave rectifier and high-frequency (45kHz) power factor correction
(PFC) converter. The output of the PFC converter is a regulated DC
voltage at approxi385V. This voltage is converted down to 24, 28
or 48VDC nominal, depending on the model. This is done by a forward
converter operating at 150 kHz. The output of this converter goes through
a rectifier, filter and ORing diode to the module output. Feedback from
the remote sense terminals back to the forward converter pulse-width
modulator regulates the output voltage and keeps it constant.
7.2
Power Factor Correction. This high-frequency converter circuit, switch-
ing at 45kHz, achieves a power factor of 0.99 by forcing the AC input
current into a sinusoidal waveform, in phase with the input voltage. The
input current is a smooth sine wave of much lower amplitude than the
normal series of high-amplitude, input current pulses that are present in a
unit without power factor correction. The result is lower RMS input cur-
rent for a given output power level.
7.3
Cooling Fan. Another output from the forward converter is rectified,
filtered and used to power the DC ball bearing cooling fan in the module.
7.4
Interface Signals. The module incorporates a number of interface con-
trol and supervisory signals which operate off internal circuits and are
brought to the outside. These include remote enable, which enables or
inhibits the entire rack, remote sensing, remote output adjust and a cur-
rent share connection which permits operating the rack in parallel with
other racks for increased power. Other signals brought out of the rack for
each module are AC good and DC good.
