(12) United States Patent
`US 8,638,008 B2
`(10) Patent N0.:
`Baldwin et al.
`
`(45) Date of Patent: Jan. 28, 2014
`
`US008638008B2
`
`(54)
`
`(75)
`
`380 VOLT DIRECT CURRENT POWER
`DISTRIBUTION SYSTEM FOR
`INFORMATION AND COMMUNICATION
`TECHNOLOGY SYSTEMS AND FACILITIES
`
`Inventors: Mark Harry Baldwin, Davidsonville,
`MD (US); David Edmund Geary,
`Bowie, MD (US); Timothy Edward
`Martinson, Erie, PA (US)
`
`(73)
`
`Assignee:
`
`Direct Power Tech IP, LLC, Bowie,
`MD (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 507 days.
`
`(21)
`
`App1.No.: 12/976,383
`
`(22)
`
`Filed:
`
`Dec. 22, 2010
`
`Prior Publication Data
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,712,779 A *
`5,861,684 A
`6,278,624 B1
`7,141,894 B2
`7,421,599 B2
`7,492,057 B2 *
`7,560,831 B2
`7,633,181 B2
`2002/0057018 A1
`2008/0278003 A1
`2009/0072624 A1
`2009/0309570 A1
`2010/0042860 A1
`2010/0275441 A1
`
`* cited by examiner
`
`............... 363/69
`
`................. 307/64
`
`1/1998 Sheppard et a1.
`1/1999 Slade et a1.
`8/2001 Nelson
`11/2006 Kraus
`9/2008 Bahali et a1.
`2/2009 Baldwin et a1.
`7/2009 Whitted et a1.
`12/2009 Gross et a1.
`5/2002 Branscomb et a1.
`11/2008
`Pouchet et a1.
`3/2009
`Towada
`12/2009
`Lehmann et a1.
`2/2010
`Kwon et a1.
`11/2010
`Rasmussen et a1.
`
`Primary Examiner 7 Robert L. Deberadinis
`(74) Attorney, Agent, or Firm 7 Ronald E. Prass, Jr.; Prass
`LLP
`
`(65)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`US 2011/0148213A1
`
`Jun. 23, 2011
`
`(57)
`
`ABSTRACT
`
`Related US. Application Data
`
`Provisional application No. 61/289,109, filed on Dec.
`22, 2009.
`
`(2006.01)
`
`Int. Cl.
`H02] 9/00
`US. Cl.
`USPC ............................................. 307/64; 307/147
`Field of Classification Search
`USPC .................................................... 307/ 147, 64
`See application file for complete search history.
`
`A method and a modular direct current power distribution
`system. A distribution panel may receive alternating current
`power with a voltage range between 200 volts and 15000
`volts. A modular rectifier may convert the alternating current
`power from the distribution panel to direct current power with
`a range of 250 volts to 600 volts. An end feed box may receive
`alternative energy power from an alternative energy power
`source. A power pathway module may distribute the direct
`current power from the modular rectifier to a set of informa-
`tion and communication technology equipment. An electrical
`protection system may guard against electrical damage.
`
`10 Claims, 9 Drawing Sheets
`
`PQM
`522
`
`
` Busway 5708
`
`Rectifier I Power
`50
`4
`I Meter
`
`Cabinet
`M
`
`Page 1 of 15
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`VOLTSERVER EXHIBIT 101 1
`
`-- Battery
`
`516
`
`Drop
`518
`
`DC Meter
`
`Page 1 of 15
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`VOLTSERVER EXHIBIT 1011
`
`

`

`US. Patent
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`Jan. 28, 2014
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`Sheet 1 0f9
`
`US 8,638,008 B2
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`102
`
`102
`
` m
`
`Figure 1
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`US. Patent
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`Jan. 28, 2014
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`Sheet 2 0f9
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`US 8,638,008 B2
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`US. Patent
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`Jan. 28, 2014
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`Sheet 3 0f9
`
`US 8,638,008 B2
`
`Collector Bus M
`
`Breaker
`
`&
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`Breaker
`
`Bar B1 fl
`
`BOX A
`
`Bar A1 fl
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`U.S. Patent
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`Jan. 28, 2014
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`US. Patent
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`Jan. 28, 2014
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`Sheet 7 0f9
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`US 8,638,008 B2
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`Trip m
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`Trip m
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`Shunt
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`US. Patent
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`Jan. 28, 2014
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`Sheet 8 0f9
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`US 8,638,008 B2
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`Receive AC Power (200V-15kV) &
`
`Convert AC Power to DC Power (25OV-900V,
`Nominal 380V) fl
`
`Distribute DC Power &
`
`Receive Alternative Power &
`
`Distribute Alternative Power m
`
`Stabilize Voltage Supply m
`
`Transmit Nominal 380 DCV Power to Set ICT
`
`Equipment fl
`
`End
`
`800
`
`Figure 8
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`Page 9 of 15
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`US. Patent
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`Jan. 28, 2014
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`Sheet 9 0f9
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`US 8,638,008 B2
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`Receive DC Power (250V-900V,
`Nominal 380V) fl
`
`Door
`
`
`
`
`
`Shunt DC Power
`Position?
`(250V-900V,
`
`M
`Nominal 380V) %
`
`
`
`Transmit DC Power (250V-900V,
`Nominal 380V) to lCT Equipment 906
`
`
`
`Transmit Battery
`Power (12 VDC) to
`lCT Equipment 910
`
`900
`
`FiEJre 9
`
`Page 10 of 15
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`

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`US 8,638,008 B2
`
`1
`380 VOLT DIRECT CURRENT POWER
`DISTRIBUTION SYSTEM FOR
`INFORMATION AND COMMUNICATION
`TECHNOLOGY SYSTEMS AND FACILITIES
`
`BACKGROUND
`
`1. Cross Reference to Related Application
`This application is based upon and claims benefit of
`copending and co -owned U. S. Provisional Patent Application
`Ser. No. 61/289,109 entitled “400v DC POWER DISTRIBU-
`TION SYSTEM FOR ENERGY EFFICIENT INFORMA-
`TION AND COMMUNICATION TECHNOLOGY SYS-
`TEMS AND AN INTEGRAL
`POWER/ENERGY
`CONTROL SYSTEM FOR THE INTEGRATION OF
`RENEWABLE ENERGY SOURCES AND ENERGY
`STORAGE,” filed with the US. Patent and Trademark Office
`on Dec. 22, 2009 by the inventors herein, the specification of
`which is incorporated herein by reference.
`2. Field of the Invention
`
`The present invention relates generally to an energy effi-
`cient
`information and communication technology (ICT)
`power distribution system. The present invention further
`relates to the direct current (DC) electrical distribution of
`nominal 380 volts power, with a range of 250 volts to 600
`volts, to DC powered ICT loads.
`3. Introduction
`
`In recent years, interest in how electricity is generated,
`transported, and used has increased. The continued growth of
`digital electrical loads in today’s markets has finally reached
`a pattern and density that may indicate change to power
`generation and delivery.
`One solution may be to create methods and infrastructure
`to enable digital loads to be supported by digital power, such
`as direct current (DC) power. Research has provided the
`insight that no one solution minimizes carbon footprint or
`energy dependence. Modern power electronics, coupled with
`the need to expand the use of renewable energy sources, may
`make DC power a standard option in a modern power grid
`infrastructure.
`
`SUMMARY OF THE INVENTION
`
`A method and a modular direct current power distribution
`system. A facility may receive alternating current power with
`a voltage range between 200 volts and 15000 volts.Amodular
`rectifier may convert the alternating current power from the
`distribution panel to direct current power with a range of 250
`volts to 600 volts. An end feed box may receive alternative
`energy power from an alternative energy power source. A
`power pathway module may distribute the direct current
`power from the modular rectifier to a set of information and
`communication technology equipment. This direct current
`power may also be used to feed other facility loads, such as
`lighting, and motorized mechanical systems, such as heating,
`ventilating, and air conditioning systems. An electrical pro-
`tection system may guard against electrical damage.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Understanding that these drawings depict only typical
`embodiments of the invention and are not therefore to be
`
`considered to be limiting of its scope, the invention will be
`described and explained with additional specificity and detail
`through the use of the accompanying drawings in which:
`FIG. 1 is an exemplary high reliability direct current power
`distribution system.
`
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`FIG. 2 illustrates an elevation plan of a single row system
`which provides a twice redundant 380v DC power feed to one
`row of equipment racks fed by an overhead busway.
`FIG. 3 shows specific components of the modular direct
`current power distribution system, with increased safety com-
`pared to alternating current systems.
`FIG. 4 illustrates in a wiring diagram a dual-source direct
`current power distribution system.
`FIG. 5 illustrates an electrical protection system for the
`modular direct current power distribution system.
`FIG. 6 illustrates further features of an individual backup
`power system.
`FIG. 7 illustrates in a wiring diagram a battery pack mount-
`ing rack module.
`FIG. 8 illustrates, in a flowchart, a method for distributing
`direct current power to information and communication tech-
`nology equipment.
`FIG. 9 illustrates, in a flowchart, a method forusing a shunt
`to protect the modular direct current power distribution sys-
`tem.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`Additional features and advantages ofthe invention will be
`set forth in the description which follows, and in part will be
`obvious from the description, or may be learned by practice of
`the invention. The features and advantages of the invention
`may be realized and obtained by means ofthe instruments and
`combinations particularly pointed out
`in the appended
`claims. These and other features of the present invention will
`become more fully apparent from the following description
`and appended claims, or may be learned by the practice ofthe
`invention as set forth herein.
`Various embodiments of the invention are discussed in
`
`detail below. While specific implementations are discussed, it
`should be understood that this is done for illustration pur-
`poses only. A person skilled in the relevant art will recognize
`that other components and configurations may be used with-
`out parting from the spirit and scope of the invention.
`The present invention comprises a variety ofembodiments,
`such as a method, a direct current (DC) power distribution
`system, and a set of instructions, and other embodiments that
`relate to the basic concepts ofthe invention. The set ofinstruc-
`tions may reside in a storage medium. The set of instructions
`may be executable by a processor to implement a method for
`DC power distribution. The set of instructions may also reside
`external to the local system, such as integration with a con-
`figuration management database (CMDB) to complete inter-
`national technology infrastructure library (ITIL) objectives.
`Conventional systems may not satisfy some basic energy
`system requirements. A more useful power distribution sys-
`tem may provide a high reliability energy source and delivery
`for computing, communications,
`laboratory, research and
`medical care loads. A modular DC power distribution system
`may provide energy storage to ride through normal power
`source outages and for peak demand or peak shaving loads. A
`modular DC power distribution system may use renewable
`energy sources for free energy generation. A modular DC
`power distribution system may improve energy efficiency for
`lighting and motor loads.
`DC power distribution set at a nominal 380 volts may allow
`for the elimination of high cost static switches and active
`paralleling of alternating current (AC) sources, as coupling
`multiple DC sources may be as simple as matching output
`voltages. Information and communication technology (ICT)
`equipment equipped with 380 volt DC power supplies,
`instead ofAC power supplies, may operate with 20-40% less
`
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`US 8,638,008 B2
`
`3
`heat, reduce power consumption by up to 30%, increase sys-
`tem reliability, offer flexibility to installations, and decrease
`maintenance requirements.
`A high reliability 380 volt DC electrical power distribution
`system may avoid the disadvantages of an AC power system.
`The DC power distribution system may be safer than a com-
`parable AC system by the use of faster acting circuit protec-
`tion devices, lCT equipment-based battery back-up, and the
`use of blocking diodes.
`Additionally, lower component count may result in higher
`system efficiency, greater reliability, less maintenance, and
`lower cost. A modular and flexible design may allow for
`system growth as lCT power requirements grow. A modular,
`highly efficient rectifier design may provide a plug-and-play
`modular growth capability and internal redundancy. Addi-
`tional value may be added by integrating real-time control of
`individual rectifiers to match information technology (IT)
`computing, storage, communication, and heating, ventilat-
`ing, and air conditioning (HVAC) requirements. Further man-
`agement may provide control over power demand compared
`to IT uptime value to allow shedding of less critical applica-
`tions while on reserve power during an outage. A power
`pathway module, such as a modular busway system or wire
`and conduit with panel boards, may enable growth and permit
`redundant DC sources at critical loads. DC rated plug-in
`modules may be energized on the bus without interruption of
`critical loads. DC power distribution may avoid downstream
`transfer switches or static switches. DC power distribution
`may eliminate harmonics found on AC systems. DC power
`distribution may eliminate stand-alone uninterruptible power
`supply requirements. DC power distribution may provide a
`more eflicient
`interface with alternative energy power
`sources, or “green” power sources, that typically produce a
`DC output, such as wind power, solar power, fuel cells, zinc-
`bromine batteries, and other alternative energy power
`sources.
`
`A modular DC power distribution system may have a
`nominal voltage of 380 volts with a high voltage operational
`range between 250v DC to 600v DC utilizing new industry
`provided components rated and configured to provide this
`new electrical distribution system topology. Power to this
`power distribution system may originate through a modular
`rectifier system which is configured for this system topology
`with the capability of converting 208 volts, 400 volts, 480
`volts, 600 volts, 5 kilovolts, or 15 kilovolts of AC to a regu-
`lated 380 volts DC with an operating output range of250 volts
`DC to 600 volts DC.
`
`The modular DC power distribution system may imple-
`ment an electrical protection system to protect against elec-
`trical damages, such as arc flash exposure, electrical surges,
`general faults, and short circuits. The electrical protection
`system may include 380v DC rated fast acting circuit breakers
`and fuses, blocking diodes, shunt trips, spring activated latch-
`ing connectors for plug-and-play capabilities, voltage meter-
`ing, current metering, and power metering. Blocking diodes
`my block power or current transmissions from back-feeding
`fault currents to other areas during fault conditions. The
`modular DC power distribution system may have an overhead
`busway system with an end feed box containing a DC power
`meter and either a center tap ground, positive ground, or
`negative ground. The center tap ground may have and imped-
`ance center tap ground using grounding resistors, leakage
`current sensors on ground leads, and fast acting fusing to
`minimize arc flash exposure. The overhead busway system
`may have branch circuit drop boxes for each equipment rack
`containing 380v DC rated fast acting circuit breakers, fuses,
`ground fault detection and protection, and 380v DC power
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`metering. The modular DC power distribution system may
`use 380v DC rated drop cords connected to 380v DC rated
`plug strip power distribution units (PDUs) or 380v DC rated
`pin and sleeve connectors. The modular DC power distribu-
`tion system may be made inherently safer by incorporating
`fault activated current and voltage limiting devices and con-
`trol systems to quickly and safely isolate and disconnect short
`circuits occurring during installation, maintenance or opera-
`tions of the power distribution system.
`A modular DC power distribution system may use a four
`bus overhead busway system may feed equipment racks from
`two differing sources, such as a primary source using a rec-
`tifier system and a secondary source using an alternative
`energy source, such as wind, solar, full cell, zinc-bromine
`battery or others. The modular DC power distribution system
`may be fed from a DC power collector bus operating between
`250 volts DC to 600 volts DC. AnAC utility power source or
`an AC generator power source may feed the collector bus via
`a modular rectifier. An alternative energy power source may
`provide power to the collector bus, such as solar cells, wind
`turbines, fuel cells, zinc-bromine batteries, and an engine
`generator. A large scale energy storage flow batteries may
`feed the collector bus through DC to DC converters. An
`energy storage module, such as an ultra-capacitor system or a
`flywheel system, may provide short-term energy to allow for
`uninterrupted transitions between utility powers, generator
`power and large scale energy storage. The energy storage
`module may bi-directionally stabilize the DC power on the
`power pathway module.
`The modular DC power distribution system may be con-
`structed from commercial off the shelf (COTS) modules. The
`modular DC power distribution system may have an energy
`storage module. The energy storage module may be a DC
`power system with a combination of flywheels, ultra-capaci-
`tors, and large grid edge scale energy storage to provide
`voltage stabilization and ride thru during a utility outage.
`A single power quality monitoring (PQM) module may
`monitor multiple system points for AC and DC power. The
`PQM module may be a network based system that allows
`system monitoring from any place that internet access is
`available. Multiple point monitoring may provide total sys-
`tem performance data from a single, time synchronized, sys-
`tem.
`
`The modular DC power distribution system for a data cen-
`ter may utilize a cord or safety plug connector equipped with
`a spring loaded hasp, and a pilot circuit. The pilot circuit may
`ensure that circuit breakers feeding the plugs are shunt tripped
`and in the offposition prior to connecting or disconnected the
`380 volts DC plugs or connectors. The modular DC power
`distribution system may use a busway system. The critical
`load may be distributed by four busway bars for redundancy
`or for double capacity to the critical load. A DC to DC con-
`verter converts a high voltage range to 380 volts DC for direct
`distribution to computer loads. DC rated circuit breakers may
`be used in place of DC rated fuse functionality for short
`circuit protection and over-load protection. Circuit drop
`boxes may also be equipped with ground fault detection and
`protection and 380 volts DC power metering. The busway
`may feed a plug strip or pin and sleeve connectors rated at 380
`volts DC and up to 200 amperes. A plug strip may utilize new
`receptacles rated for 380v DC power distribution systems.
`The computer loads supplied by the modular DC power
`distribution system may be lCT equipment. The lCT equip-
`ment may be housed within equipment racks equipped for
`inherent safety. A door of the equipment rack may be con-
`nected to a shunt trip circuit in order to shunt trip the DC
`power at the busway when equipment rack doors are opened
`
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`US 8,638,008 B2
`
`5
`by a system operator or maintainer. The ICT equipment
`within the equipment racks may be equipped with an internal
`power converter. An internal power converter may convert the
`DC power with a range of 250 volts to 600 volts to an internal
`DC power with a low voltage range of 2 volts to 60 volts for
`internal equipment utilization. Additionally,
`the internal
`power converter may convert the nominal 3 80 volts DC to AC
`to migrate existing equipment to the new system. The modu-
`lar DC power distribution system may have an internal remote
`battery pack connected to the low voltage side of each power
`supply for system back-up power during occasions where the
`380 volts of DC power is not available. The equipment rack
`may be equipped with a battery pack mounting rack module
`to hold an individual battery pack for each piece of ICT
`equipment. The individual battery packs may be equipped
`with an internal monitoring module to display battery health.
`In addition, each battery pack may have the capability of
`communicating battery capacity and health through indi-
`vidual ICT power supplies. Battery packs may have the capa-
`bility of being charged via the ICT power supplies or from an
`independent charging system separate from ICT power sup-
`plies.
`FIG. 1 is an exemplary high reliability DC power distribu-
`tion system, indicated generally as 130. Normal utility power
`and generator power may be supplied to distribution panels
`102 at approximately 277 to 480 volts AC. A plurality of
`rectifiers 104 may provide 250 volts DC to 600 volts DC, with
`a nominal voltage of 380 DC, to collector busses 106. Energy
`storage systems 108 may provide rapid emergency DC power
`to the collector busses 106 upon loss of AC power to the
`rectifiers. The collector busses 106 may feed power to a
`distribution bus 110, which may be divided into parallel,
`redundant busses 112 separated by normally open circuit
`breakers 114. The distribution bus 110 may feed power to
`both ends of a busway 116 having dedicated drops 118, such
`as a plug-in unit circuit drop box, to a plurality of rack 120
`mounted DC-to-DC converters 122 or directly to servers or
`other equipment that operate at the voltage ofthe busway 1 16.
`While the nominal voltage on the busway 116 may be
`approximately 380 volts DC, high voltage DC power may be
`approximately between 250 volts DC to 600 volts DC.
`An engine or generator, typically a diesel engine system,
`may be on the supply side of the system. The engine or
`generator may typically tied in at the service entrance point
`for the facility. Such an engine or generator may provide a
`rapid startup, emergency electrical power upon loss of power
`from the service utility.
`FIG. 2 illustrates an elevation plan of a single row system
`200 which provides a twice redundant 380v DC power feed to
`one row of equipment racks 202 of ICT equipment 204 fed by
`a power pathway module, such as an overhead busway 206.
`The overhead busway 206 may be configured with four bus
`bars and offers two paths of power for each equipment rack
`202. Each end of the busway system 206 is fed by a rectifier
`system 208 via an end feed box 210. An AC to DC rectifier
`208 may be utilized to act as the front-end power source for a
`high voltage DC distribution system that supports an entire
`critical operations environment instead of using a single use
`rectifier for a specific component. The high voltage DC power
`may be approximately 250 volts DC to 600 volts DC, with a
`nominal DC voltage of 380, although other appropriate volt-
`ages may be used. The rectifier system 208 may be con-
`structed of 20 kW modules, with up to 14 modules per rack
`structure. Other module sizes and equipment rack 202 con-
`figurations may be provided for this purpose. The rectifier
`system 208 may perform hot swappable replacements, addi-
`tions or subtractions. The rectifier systems may be connected
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`to a battery cabinet 212 to provide energy storage back-up
`power when the rectifier AC power source is cycled between
`multiple sources, such as utility service 214 and engine gen-
`erator service 216. Other forms of energy storage have been
`employed within this 380v DC power system in place of
`typical batteries, such as flywheels, flow batteries, fuel cells
`and alternative energy sources, in order to take advantage of
`the ease of integration with DC power sources.
`FIG. 3 illustrates, in a block diagram, specific components
`300 of the modular DC power distribution system 100, with
`increased safety compared to AC systems. In this embodi-
`ment, 380 v DC rated circuit breakers 302 feed 380 v DC
`power from the collector bus 304 to a spring actuated, safety
`latch-equipped connector 3 06, or a safety plug connector with
`a spring loaded hasp and pilot circuit. These spring actuated,
`safety latch-equipped connectors 306 may prevent energizing
`of the circuit until the male and female portions of the con-
`nector are firmly connected and latched. The latching mecha-
`nism 306 may be connected to a shunt-trip mechanism within
`the source breaker 302 by a signal cable 308. This connector
`arrangement may connect the source power to the overhead
`busway distribution system 310 for each equipment rack 312
`from a circuit drop off 314 ofthe busway system 310. The 380
`v DC rack power is provided by 380 v DC rated plug strips
`316, connected to the circuit drop offs 314 by a spring actu-
`ated, safety latch-equipped connector 306 with an associated
`signal cable 308.
`The busway 310 may provide a unique application. Instead
`ofproviding anAC distribution system with a single feed, the
`busway 310 may provide a DC distribution system that may
`be fed from multiple DC voltage matched sources via an end
`feed box 318. Alternatively, the busway 310 may be fed from
`two separate sources, one on each end, utilizing two bus bars
`320 each. The busway 304 may have four separate bus bars
`320 with a maximum rating of approximately 600 VDC for
`each. Two bus bars 320 may be fed by a primary source,
`labeled A, and the other two bus bars 320 may be fed by a
`secondary source, labeled B. The drops 314 from the busway
`310 may then be selectable from either source. In one
`embodiment, the busway 310 may provide high voltage DC
`power to equipment rack locations within a compact package,
`with hot swappable or movable connectors that may be fed
`from separate DC power sources. The high voltage DC power
`may be approximately 250 volts DC to 600 volts DC, with a
`nominal DC voltage of 380. Circuit drops 314 may be
`equipped with suitable 380v DC rated circuit breakers 322
`and accompanied with a 380v DC rated fuse 324 for added
`protection. In some embodiments, the secondary source may
`be a similarly configured, redundant rectifier rack and energy
`storage system or an alternative energy power source, such as
`a wind turbine, solar cell, fuel cell, zinc-bromine battery, or
`engine generator.
`FIG. 4 illustrates in a wiring diagram a dual-source DC
`power distribution system 400. A center point grounding
`configuration may limit a 380v DC power system to +l90v
`DC and —l90v DC from conductor to ground. This configu-
`ration may be fed from a typical AC power source or service
`transformer 402 and rectified to 380v DC through a system
`rectifier 404. The rectifier may be coupled with an energy
`storage system, such as a battery cabinet 406, to provide
`power ride-through during AC source outages and transfers.
`The system rectifier 404 may then feed 380v DC to the
`busway 408, having four bus bars 410, with the connection
`made at an end feed box 412. The end feed box 412 may
`perform system grounding in a similar manner as a separately
`derived source within an AC system. The end feed box 412
`may ground the positive and negative lines thorough high
`
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`US 8,638,008 B2
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`7
`impedance center tap ground utilizing grounding resistors
`(GR) 414 and leakage current sensors (LCS) 416 leading to a
`main ground bus (MGB) 418. The end feed box 412 may also
`house fast acting 380v DC fuses 420 for added circuit pro-
`tection. The busway 408 may feed equipment loads 422
`through circuit drop boxes 424 that contain 380v DC branch
`circuit breakers 426 and fuses 428. Additional protection may
`be provided with ground fault circuit 430 sensing and protec-
`tion as built within the 380v DC circuit breakers 424, such as
`a fault activated current and voltage limiting control module
`to isolate and disconnect a short circuit. Alternative energy
`sources 432 may be integrated and connected to this 380v DC
`power distribution system via a voltage converter 434. Alter-
`native energy sources 432 may be a solar cell 436; a wind
`turbine 438; fuel cell 440; a large scale energy storage 442,
`such as zinc-bromine battery 442; or a back-up AC power
`engine generator 444.
`FIG. 5 illustrates an electrical protection system 500 for the
`modular DC power distribution system 100. The modular DC
`power distribution system may be configured as a floating
`system without either the positive, negative or center point
`grounded. A similar configuration may be created with either
`the positive leg grounded or the negative leg grounded. This
`configuration may be fed from a typical AC power source 502
`or service transformer 502 and rectified to 380v DC through
`a system rectifier 504. The system rectifier 504 may be
`coupled with an energy storage system, such as a battery
`cabinet 506, to provide power ride-through during AC source
`outages and transfers. The system rectifier 504 may then feed
`380v DC to the busway 508 with the connection made at an
`end feed box 510. The end feed box 510 may perform system
`grounding in a similar manner as a separately derived source
`within and AC system. An AC power meter 512 may be
`positioned on the AC input feed to the rectifier 504 to allow
`for input power documentation. Current transformers (CTs)
`are used to capture current in amps on the AC power feed. A
`380v DC power meter 514 is shown on the output of the
`system rectifier 504 and may be incorporated within the
`busway end feed box 510, within the rectifier 504, or within a
`separate enclosure. DC current measurements may be
`achieved using a direct connection to the meter 514, a suitably
`rated shunt, or through suitably rated Hall Effect CTs. Branch
`circuit metering 516 may be incorporated within busway
`circuit drop boxes 518 connected to the load 520. DC current
`measurements may be achieved using a direct connection to
`the meter, a suitably rated shunt, or through suitably rated
`Hall Effect CTs. All meters are networked together using
`Modbus RTU communication protocol. A PQM module 522
`may retrieve data from each meter using a data acquisition
`system. Data communications may use wired and wireless
`communications.
`
`FIG. 6 illustrates further features of an individual backup
`power system 600. Each equipment load 602 may be con-
`nected to an individual battery 604 for back-up power
`requirements. The individual equipment power supply unit
`(PSU) 606 may be configured to accept 380v DC at the input
`and provide 8 to 55 volts DC on the output, with a nominal
`voltage of 12 volts DC. The PSU 606 may use an internal DC
`to DC power converter 608 to convert the DC power with a
`range of 250 volts to 600 volts to an internal DC power with
`a range of 2 volts to 60 volts for internal utilization. The
`individual equipment PSU 606 may alternatively be config-
`ured to provide other DC voltages as desired by equipment
`components within the equipment. A voltage regulator mod-
`ule (VRM) may adjust the nominal 12 volts to level appro-
`priate for loads 612 capable ofaccepting legacy voltage levels
`and for loads 614 capable of accepting silicon voltage levels.
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`An individual battery 604 may be connected on the low
`voltage DC side of the PSU 606 from 8-55V DC. The battery
`connection may be similar to a typical battery connection
`within a laptop computer with battery metering, charging and
`discharge management similar to how a laptop computer
`operates today. The individual battery pack 604 may have an
`internal monitoring module 616 to check battery health.
`FIG. 7 illustrates in a block diagram a battery pack mount-
`ing rack module 700. Servers or equipment with integral
`batteries within equipment racks 702 may be powered by
`380v DC from the overhead busway systems 704 under nor-
`mal operating conditions. The overhead busway system 704
`may receive DC power from an end feed box 706. Equipment
`racks 702 may be powered by circuit drops 708 from the
`busway 704. Connectors with shunt trip interlocks 710 may
`be used for rackpower connections to the 380v DC source bus
`704. Each rack 702 may be configured with a door sensor
`switch 712 which, when upon sensing that a rack door 714 is
`open, may send a shunt trip signal to the circuit breaker within
`the circuit drop box 708 feeding the associated rack 702. This
`action may disconnect 380v DC power from the rack 702 and
`the ICT equipment 716 within the rack 702 may default to
`battery pack (BP) 718 back-up operation while the door 714
`is open. Once the door is re-closed, the source breakers may
`be reset and closed to again provide normal 380 volts DC
`power via a set of PSUs 720 and a set of 400 volt DC plug
`strips 722 to the ICT equipment 716 within the associated
`rack 702.
`FIG. 8 illustrates, in a flowchart, a method 800 for distrib-
`uting direct current power to information and communication
`technology equipment. The modular rectifier 104 may
`receive AC power with a voltage range between 200 volts and
`15000 volts (Block 802). The modular rectifier 104 may
`convert AC power to DC power with a voltage range between
`250 volts and 600 volts, with a nominal voltage of 380 volts
`(Block 804). A power pathway module 116, such as