Note: Descriptions are shown in the official language in which they were submitted.
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SC-5296-C
VENTILATION ARRANGEMENT FOR POWER SYSTEM
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to ventilation arrangements and more
particularly to a ventilation arrangement for a power system.
Description of the Related Art
Various cooling and ventilating arrangements are known for removing heat
dissipation
from electronic devices. For example, the following U.S. Patent Nos.
illustrate arrangements
to direct ventilating air flow: 3,641,419; 4,674,004; 5,136,464; 5,646,825;
and 5,800,258. In
the aforementioned 3,641,419, power supply modules of an AC to DC converter
include side
panels, top panels and fans to provide a horizontal airflow pattern through
each individual
module in an array. The arrangement in the aforementioned 4,674,004 provides a
ducting
structure to individual printed circuit cards in an array of parallel cards,
with each duct
including a plurality of spaced apertures to direct individual streams of
cooling air to respective
areas of the printed circuit cards. In the aforementioned 5,136,464, a housing
structure houses
a two or more storied configuration of electrical components and a confluence-
preventing
arrangement prevents air exhausted from a lower component section and air
introduced into an
upper component section from being combined together. The confluence-
preventing
arrangement includes a support section that supports the electronic components
in the upper
component section and a confluence preventing section below the support
section. In the
aforementioned 5,646,825, a cooling device for a switch cabinet includes first
and second heat
exchangers in respective first and second chambers. Both heat exchangers are
supplied from a
common compressor. A ventilation system for a cabinet in the aforementioned
5,800,258
includes multiple fan units that are disposed at mid-height in the cabinet
between upper and
lower stacked component arrangements, the fans being arranged in pairs with
their respective
air intake direction facing toward each other. The spaced-apart fan pairs form
a horizontal air
duct that extends to the exterior of the cabinet.
While these arrangements may generally be useful for their intended purposes,
they do
not relate to the field of medium voltage power electronic devices for such
applications as
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high-speed source transfer where power electronic devices such as SCR's or
thyristors generate
large volumes of heat and portions of the power electronic assemblies are at
diverse medium
voltages during operation.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to provide a
ventilation
arrangement for a medium-voltage power electronic device that provides
desirable ventilation
control while also providing insulation to the medium voltage components.
It is another object of the present invention to provide directed air flow to
power
electronic assemblies of power electronic modules that each have different
medium voltages
applied thereacross.
These and other objects of the present invention are efficiently achieved by
the
provision of a ventilation arrangement for power electronic equipment
including a plurality of
power electronics assemblies. The ventilation arrangement includes a common
source of
directed air flow, spaced apart insulating ducts for providing air flow from
the common
source, and arrangements connected to each of the spaced apart insulating
ducts for distributing
and directing the air flow to each of the power electronics assemblies In a
preferred
embodiment, the insulating ducts are fabricated from extremely low leakage
material that
provides extremely low tracking characteristics.
BRIEF DESCRIPTION OF THE DRAWING
The invention, both as to its organization and method of operation, together
with
further objects and advantages thereof, will best be understood by reference
to the specification
taken in conjunction with the accompanying drawing in which:
FIG. 1 is a right-side elevational view, with parts removed for clarity, of a
power
system provided with a ventilation arrangement in accordance with the present
invention;
FIG. 2 is a top plan view of portions of the power system of FIG. 1 with parts
removed
for clarity to illustrate the ventilation arrangement of the present
invention;
FIG. 3 is a perspective view of a power electronics assembly of the power
system of
FIGS. 1 and 2; and
FIGS. 4 and S are respective front and rear perspective views of a plenum of
the
ventilation arrangement of FIGS. 1 and 2.
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DETAILED DESCRIPTION
Referring now to FIGS. l and 2, a ventilation arrangement 110 in accordance
with the
present invention is useful to provide a predetermined pattern and volume of
directed cooling air
within an enclosure 120 of a power system 112. In an illustrative embodiment,
the power system
112 includes power electronic assemblies 114, 116 and 118 (best seen in FIG.
2) housed within
the enclosure 120. In a specific application, medium voltages (e.g. 2-34.5 kv)
are applied across
the power electronic assemblies 114, 116 and 118. For example, in an
illustrative application,
each of the power electronic assemblies 114, 116 and 118 corresponds to an
individual phase or
pole of a multi-phase AC power system. The power electronic assemblies 114,
116 and 118
dissipate large quantities of heat such that large volumes of air flow are
required to ensure that
the assemblies are maintained at suitable operating temperatures to allow
adequate performance
of their functions. The power-electronic assemblies 114, 116 and 118 are
supported within the
enclosure 120 via suitable insulators, for example as illustrated generally in
FIG. 1 at 117, 119.
The ventilation arrangement 110 includes an air intake section 122 (FIG. 2)
which draws
in air at 121 via an air intake 123 and high pressure blowers at 124. In a
specific embodiment,
two blowers 124a and 124b are provided for redundancy in case one of the
blowers should
become non-functional. The air is drawn through filters 125 and through the
high pressure
blowers 124 and delivered into a plenum 126. The plenum 126 communicates to
insulating ducts
128. In the illustrative embodiment, three insulating ducts 128a, 128b and
128c (FIG. 2) are
connected to supply air to respective insulating plenums 130a, 130b and 130c,
one to supply air
to each of the power electronic assemblies 114, 116, and 118. The air is
directed through the
power electronic assemblies 114, 116 and 118 and exits at 134 into the
interior of the enclosure
120 and out of the enclosure 120 through an exhaust outlet at 136. Both the
intake 123 and the
outlet 136 include suitable vandal-deterrent features. The plenum 130 is
fabricated from
insulating materials such as GPO-3 fiberglass material. The insulating duct
128 is also fabricated
from insulating material. In a preferred embodiment for medium-voltage
applications, the
insulating duct 128 is fabricated from extremely low leakage material,e.g.
poly methyl
methacrylate (acrylic) or cycloaliphatic epoxy, that provides extremely low
tracking
characteristics. For example, the insulating duct 128 provides appropriate
dielectric withstand
(e.g. BIL voltages in the range of 50-150kv) for the various maximum potential
differences
between the power electronic assemblies 114, 116 and 118 and the connected air
delivery
components, e.g. the plenum 126 which is fabricated from steel in a specific
embodiment.
Refernng now additionally to FIG. 3, each of the power electronic assemblies
114, 116
and 118 includes power electronic stages or modules 140 that are stacked one
atop the other, e.g.
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as illustrated at 140a, 140b and 140c. In an illustrative embodiment, the
power electronic stages
140 include compression-mounted power electronic devices 141 such as
semiconductors that are
clamped between interposed heat sink arrangements 142, e.g. as illustrated at
142a and 142b.
The heat sinks 142 include spaced fins 143 that are generally planar, e.g. as
illustrated at 143a,
143b. The heat sinks 142 are arranged such that the end portion 150 faces the
plenum 130, the
air being directed out of the plenum 130 in a direction 152 between and along
the fins 143 of the
heat sinks 142, i.e. parallel to the planes of the fins 143, with the air
exiting from the front end
portion 153 of the power electronic stages 140 in a direction 154. The power
electronic stages
140 are carried or supported via angle brackets 155 so as to provide slide-in
rack mounting of the
power electronic stages 140. The angle brackets 155 are carried by opposed
structural supports
156, 158. The structural supports 156, 158 are attached to and supported by
upper and lower
channels 157 and 159. The channels 157 and 159 also provide support for the
plenum 130. The
supports 156, 158 and the channels 157, 159 also provide additional flow-
directing functions by
bounding the perimeter of the power electronic stages 140.
In one specific embodiment, bus interconnection plates 144, 146 are provided
at the front
end 153 of the power electronic stages 140 to provide electrical connection
between the stages
140a and 140b and the stages 140b and 140c respectively so as to connect the
stages 140a, 140b
and 140c in electrical series relationship. A bus connection plate 148 is
provided at the front end
of the stage 140c, a similar bus connection plate (not shown) being provided
at the front end of
the stage 140a. In a specific illustrative arrangement, the power electronic
assemblies 114, 116
and 118 are connected to bus structure generally referred to at 111, 113 in
FIG. 1. The plates
144, 146 and 148 provide additional flow efficiency by closing off the
openings at the front 153
of the power electronic stages 140, creating a high pressure zone at the
output of the plenum 130
at the back end portion 150 of the power electronic stage 140.
In another specific embodiment, a bus interconnection plate 149 is utilized to
provide
electrical interconnection between the stages, e.g. 140b and 140c, in which
case the plates 144,
146 and 148 solely provide the function of an air dam and need not be
conductive.
In accordance with important aspects of the present invention and referring
now
additionally to FIGS. 4 and 5, the plenum 130 has a general overall shape of a
parallelepiped and
includes flow concentrating and directing arrangements for cooperation with
the power electronic
devices 114, 116 and 118. Specifically, the plenum 130 includes an opening 160
within a rear
wall 162 for receiving air from the insulating ducts 128. The plenum 130 also
includes wall-
defining sides 164 and 166. The generally open front 168 of the plenum 130
faces the rear end
portion 150 of the power electronic devices 114, 116, and 118. Blocking
members 70, 72 and
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74, spanning the side walls 164, 166, are provided so as to define flow-
directing openings 176,
178, 180 and 182 that are aligned with the spacing between the heat sinks 142
of the power
electronic devices 114, 116 and 118. An equalization baffle 132 is provided in
the plenum 130
that provides more uniform air flow and is arranged to extend along the
expanse of the side walls
162, 164. In the illustrative embodiment, the equalization baffle 132 is a
generally planar
member including an array of openings 133. Thus air is efficiently channeled
and directed from
the ducts 128 through the fins 143 of the heat sinks 142 of the devices 114,
116 and 118. The
flow-directing openings 176, 178, 180 and 182 generally correspond to the
overall dimensions of
the power electronic stages 140a, 140b and 140c. In specific embodiments, the
size of the
openings 176, 178, 180 and 182 are varied to control the desired air flow
through the the power
electronic stages 140a, 140b and 140c.
While there have been illustrated and described various embodiments of the
present
invention, it will be apparent that various changes and modifications will
occur to those skilled
in the art. Accordingly, it is intended in the appended claims to cover all
such changes and
modifications that fall within the true spirit and scope of the present
invention.
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