Pumps – Condition responsive control of pump drive motor – Plural pumps having separate drive motors – supply sources,...
Reexamination Certificate
2000-12-01
2002-04-09
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
Plural pumps having separate drive motors, supply sources,...
C417S003000, C417S005000, C318S563000, C318S564000, C318S599000, C363S041000
Reexamination Certificate
active
06368064
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to power supply scheme for a plurality of fans used to cool an electronic chassis, and in particular, to an apparatus and method of providing redundant power and redundant fan speed control to a plurality of fans housed within the electronic chassis.
BACKGROUND OF THE INVENTION
Conventional electronic chassis used for high speed switching and networking applications typically are comprised of a metallic box-shaped card cage. Numerous circuit board modules (otherwise known as application cards) are slid into the electronic chassis along card guide assemblies, and are electrically attached to a backplane circuit board located along the backside of the chassis.
Each application card typically includes a large number of electronic components. As a result, these application cards generate a tremendous amount of heat, which must be removed from the chassis to protect the various electronic components within the chassis. As a result, conventional fans have been used to bring cooling air into the chassis, and, at the same time, to exhaust heated air from the chassis.
Various attempts have been made to reduce the temperature with an electronic chassis by providing a fan tray assembly, which includes a plurality of conventional fans. The fan tray assembly may then be housed within the chassis, typically along the top portion of the chassis. Cool air is circulated upward from the bottom of the chassis, through the chassis between the card guide assemblies, and the heated air is exhausted out through the top of the chassis.
Attempts have been made to provide a redundant power scheme to these conventional fans to allow the fans to continue to operate in the event of a power circuitry fail condition. For example,
FIG. 2
illustrates one example of a conventional redundant power scheme
100
for a plurality of fans
102
,
104
. As shown in
FIG. 2
, power inputs
106
,
108
are coupled together via a pair of diodes
110
,
112
. The combined power inputs
106
,
108
are then fed to a single PWM driver
114
for providing fan speed control
115
and a single DC/DC converter
116
for providing voltage to the fans
102
,
104
. The outputs of the PWM driver
114
and the DC/DC converter
116
are then delivered to all of the fans
102
,
104
. At the same time, a power bypass-straight input voltage clamp
118
is coupled from the outputs of the diodes
110
,
112
directly to the fans
102
,
104
. The voltage clamp
118
delivers the input voltage directly to the fans
102
,
104
in the event that there is a failure of either the PWM driver
114
or the DC/DC converter
116
. The input voltage is typically clamped at some specific number since the input power feeds may be as high as 72V.
There are many drawbacks to this conventional redundant power scheme. For example, the redundant power scheme shown in
FIG. 2
does not allow for speed control of the fans
102
,
104
under fault conditions. That is, when the power bypass clamp
118
is implemented, the fans
102
,
104
typically operate at the level of the input voltage. This voltage is typically higher than the maximum operating voltage of the fans
102
,
104
. As a result, the fans
102
,
104
will operate at full speed or greater, which may shorten the life of the fans
102
,
104
, and may possibly burn out the bearings of the fans or the internal circuitry of the fans. Moreover, operating the fans
102
,
104
at an accelerated speed based on the input voltage may create unacceptable and undesirable levels of acoustic noise. As a result, this conventional method of power redundancy is not a desirable option with fans that have lower operating voltages (i.e. 12V or 24V).
FIG. 3
illustrates another example of a conventional redundant power scheme
150
for a plurality of fans
152
,
154
. As shown in
FIG. 3
, power input
156
is electrically coupled to a DC/DC converter
158
, and power input
160
is electrically connected to a separate DC/DC converter
162
. The outputs of the DC/DC converters
158
,
160
are coupled together via diodes
164
,
166
to provide load sharing, and to provide redundancy in the event that one of the two DC/DC converters
158
,
162
fails. In this scenario, the input voltage is applied directly to the fans
152
,
154
, which minimizes the number of allowable speeds for the fans
152
,
154
. Moreover, this scenario does not provide full redundancy to allow the fans
152
,
154
to operate normally in the event of certain failures. For example, if power input feed
156
shuts down and the DC/DC converter
162
shuts down, then the fans
152
,
154
will not receive any power. Similarly, if power input feed
160
shuts down and the DC/DC converter
158
shuts down, then the fans
152
,
154
likewise will not receive any power.
Accordingly, it would be desirable to provide an apparatus and method of providing redundant power and redundant fan speed control to a plurality of fans that overcomes the disadvantages described above.
SUMMARY OF THE INVENTION
One aspect of the invention provides an apparatus for providing redundant power and redundant fan speed control to a plurality of fans. A first power supply input is electrically connected to a second power supply input to provide a combined power supply input. First and second fan speed controllers each having an input and an output are also provided, along with first and second power converters each having an input and an output. The combined power supply input is electrically connected to the input of the first fan speed controller and to the input of the first power converter. The combined power supply input is also electrically connected to the input of the second fan speed controller and the input of the second power converter. The output of the first fan speed controller is electrically combined with the output of the second fan speed controller to provide a combined fan speed control signal. The combined fan speed control signal is electrically connected to the plurality of fans. The output of the first power converter is electrically combined with the output of the second power converter to provide a combined fan voltage. The combined fan voltage is electrically connected to the plurality of fans. Each of the first and second fan speed controllers may preferably be a PWM driver. The plurality of fans may preferably be comprised of at least to two fans. The at least two fans may preferably be comprised of eight fans. A first diode having an input and an output, and a second diode having an input and an output may also be provided. The input of the first diode may preferably be electrically connected to the first power supply input, and the input of the second diode may preferably be electrically connected to the second power supply input. The output of the first diode may preferably be electrically connected to the output of the second diode. A third diode having an input and an output, and a forth diode having an input and an output may also be provided. The input of the third diode may preferably be electrically connected to the output of the first fan speed controller, and the input of the fourth diode may preferably be electrically connected to the output of the second fan speed controller. The output of the third diode may preferably be electrically connected to the output of the fourth diode. A fifth diode having an input and an output, and a sixth forth diode having an input and,an output may also be provided. The input of the fifth diode may preferably be electrically connected to the output of the first power converter. The input of the sixth diode may preferably be electrically connected to the output of the second power converter. The output of the fifth diode may preferably be electrically connected to the output of the sixth diode. The first power supply input may preferably be comprised of 48V, and the second power supply input may preferably be comprised of 48V. The combined fan speed control signal may preferably be electrically distributed to each of the plurality of f
Bendikas Laura M.
Greives Dane L.
3COM Corporation
Baniak Pine & Gannon
Freay Charles G.
Liu Han L
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