WO2002021663A1 - Convertisseur continu-alternatif pourvu d'un commutateur central et alimentation electrique sans coupure utilisant celui-ci - Google Patents

Convertisseur continu-alternatif pourvu d'un commutateur central et alimentation electrique sans coupure utilisant celui-ci Download PDF

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Publication number
WO2002021663A1
WO2002021663A1 PCT/US2000/040808 US0040808W WO0221663A1 WO 2002021663 A1 WO2002021663 A1 WO 2002021663A1 US 0040808 W US0040808 W US 0040808W WO 0221663 A1 WO0221663 A1 WO 0221663A1
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WO
WIPO (PCT)
Prior art keywords
coupled
pair
bus
inverter
input
Prior art date
Application number
PCT/US2000/040808
Other languages
English (en)
Inventor
Donald K. Zahrte, Sr.
David L. Layden
Frederick A. Stich
Douglas S. Folts
Original Assignee
Powerware Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Powerware Corporation filed Critical Powerware Corporation
Priority to AU2000280373A priority Critical patent/AU2000280373A1/en
Priority to PCT/US2000/040808 priority patent/WO2002021663A1/fr
Publication of WO2002021663A1 publication Critical patent/WO2002021663A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
    • H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • This invention relates generally to power conversion systems that contain energy storage devices, and more particularly to uninterruptible power supply systems capable of supplying power from an AC line voltage with or without compensation, and from a battery storage element with or without boost-conversion.
  • UPS uninterruptible power supplies
  • These UPS's utilize a bank of electric storage batteries and solid state conversion equipment in association with the utility line voltage to provide continuous electric power to a businesses computer system in the event of a loss or deviation of power quality from the utility.
  • the number of batteries contained within a UPS is dependent upon the business' length of time that it needs to operate in the event of a utility power system failure.
  • the number of power modules included in a modular UPS, or the power rating of a power conversion module in a fixed-size UPS is dependent on the overall total system load required to be supplied thereby.
  • additional power modules or additional UPS's may be purchased and integrated into an overall uninterruptible power system for the business enterprise.
  • UPS While a UPS is required to supply the entire electrical requirements of a system to which it is applied during loss of utility power, and while a business may choose to operate its UPS to condition the utility line power to provide high power quality to their computing equipment, during periods of normal utility line availability operation of the UPS may provide more inefficiencies than advantages. However, since the loss or corruption of utility line voltage often may not be predicted, disconnection of the UPS may result in momentary loss of utility power to the computing equipment and corresponding loss of computing power and electronic data.
  • typical UPS's include some form of bypass circuitry to route the utility line voltage directly to the UPS output to which the computing equipment is coupled.
  • FIG. 26 Such a configuration of a typical UPS is illustrated in FIG. 26.
  • the AC line voltage input 101 is routed through a bypass circuit 103 to the UPS output 105 coupled to the load 107.
  • this bypass circuit 103 losses resulting from rectification of the AC line input voltage as well as losses resulting from the generation of an AC output voltage waveform through switches 111, 113, 115, and 117 may be avoided.
  • this bypass circuitry 103 comprises a back-to-back silicon controlled rectifier (SCR) circuit, although other bypass circuitry configurations are also applicable.
  • SCR silicon controlled rectifier
  • the addition of the bypass circuitry 103 adds substantial cost, thermal management problems, and volume to the UPS itself. Such disadvantages have long been accepted as a necessary evil to allow high efficiency operation during periods of normal utility line voltage operation.
  • each UPS power module must be able to generate an output voltage waveform in coordination with the other UPS power modules to supply the entire connected load.
  • this configuration provides redundant operation to maximize the fault tolerance of the UPS and ensure continued electrical supply to the computing equipment.
  • each individual power module of a typical UPS system includes in-line fault isolation circuitry 123 that operates to isolate a failed power module from the output 105.
  • this fault isolation circuitry takes the form of in-line power semiconductors, back-to-back SCR's, electromechanical relays, etc. Unfortunately, this fault isolation circuitry 123 adds costs, thermal management problems, and volume to the UPS system.
  • the system and method of the present invention presents a new and improved double-conversion uninterruptible power supply utilizing a center switch circuit to disassociate the bus capacitors from the neutral connection.
  • This center switch circuit By coordinating operation of this center switch circuit, higher overall efficiencies are provided with a reduced part count, cost, and volume over prior UPS systems.
  • the double-conversion, center switch topology of the present invention overcomes the above-described and other problems existing in the art while providing three modes of operation.
  • a first mode of operation is an economy mode, where some line conditioning is accomplished but the efficiency is maintained at a very high level.
  • a second mode provides full double- conversion operation of the inverter, where the AC input utility power is converted to a bus DC and back again to an output AC voltage waveform.
  • a third mode of operation is battery conversion, where the battery is utilized by the inverter topology to generate the output AC waveform to supply power to the connected loads during loss of utility line input voltage.
  • the inverter does not utilize the battery as the DC bus, but instead steps up the battery voltage to a higher bus voltage to allow a simplified conversion to the output AC waveform.
  • the user may select the operating mode of the UPS system, while in an alternate embodiment the UPS can operate in a fully automatic intelligent mode, wherein the UPS determines whether to operate in the high efficiency bypass mode or as a conventional double-conversion inverter relying on either the utility line voltage or the battery.
  • Operation of the system of the present invention in the high efficiency mode is accomplished by opening the center switch circuit to disassociate the bus capacitors from the neutral connection and, in one embodiment, operating the inverter output switches at a rate equal to the AC line input to voltage waveform. In this way, minimal losses are incurred since the inverter is not performing any appreciable correction of the AC line power, neither regulation nor power factor correction, and the switching devices are switching at a low rate. This rate is typically 60 Hz in the United States and 50 Hz in Europe. In alternate embodiments, the output switches are merely left on to further increase the operating efficiency of the UPS.
  • the center switch circuit of the present invention provides the soft charging of the bus capacitors in a simplified manner as compared to the prior systems discussed above.
  • the center switch circuit utilizes a single active switching device, and a passive diode ring (bridge).
  • Alternate embodiments of the invention utilize different center switching configurations including both semiconductor and electromechanical switching devices alone and in combination with passive devices.
  • these various embodiments of the center switching circuit provide the fault isolation required to maintain redundancy in the event of failure of any particular power module without the necessity of additional in-line power semiconductor circuitry as discussed above.
  • FIG. 1 is a simplified block-diagrammatic, single-line schematic of an uninterruptible power supply constructed in accordance with the teachings of the present invention
  • FIG. 2 is a single-line schematic diagram of an embodiment of the present invention.
  • FIGS. 3a-3b are single-line schematic diagrams of the embodiment shown in FIG. 2 illustrating power flow in a high efficiency mode of operation;
  • FIGS. 4a-4c are single-line schematic diagrams of the embodiment shown in FIG. 2 illustrating power flow in a double-conversion line mode of operation;
  • FIGS. 5a-5d are single-line schematic diagrams of the embodiment of FIG. 2 illustrating power flow during operation in a DC boost-converter mode of operation;
  • FIGS. 6a-6b are single-line schematic diagrams illustrating an alternate embodiment of the present invention having a three-phase input and a single phase output with, and without boost conversion for the DC bus;
  • FIG. 7 is a single-line schematic diagram illustrating a further embodiment of the present invention having a three-phase input and a three- phase output with boost conversion of the DC bus;
  • FIG. 8 is a single-line schematic diagram of a further alternate embodiment of the present invention providing dual input and output couplings;
  • FIG. 9 is a single-line schematic diagram of the embodiment of FIG. 8 illustrating power flow in a high efficiency mode of operation;
  • FIGS. 10a- lOd are single-line schematic diagrams of the embodiment of FIG. 8 illustrating power flow in a battery boost DC mode of operation
  • FIGS. 1 la-1 lc are single-line schematic diagrams of the embodiment of FIG. 8 illustrating power flow in a double-conversion mode of operation
  • FIG. 12 is a single-line schematic diagram of a further alternate embodiment of the present invention providing split-phase topology
  • FIG. 13 is a single-line schematic diagram illustrating a further alternative embodiment of the present invention similar to the embodiment of FIG. 12 but providing boost-converter operation;
  • FIG. 14 is a single-line schematic diagram illustrating an alternate embodiment of the present invention providing both three-phase input and three-phase output with boost conversion
  • FIG. 15 is a single-line schematic diagram of a further alternate embodiment of the present invention utilizing a multiple center switch topology to provide controlled, independent utilization of the separate energy sources;
  • FIG. 16 is a single-line schematic diagram illustrating a further alternate embodiment of the present invention providing a single phase output
  • FIG. 17 is a partial single-line diagram illustrating an alternate embodiment of the center switch circuitry of the present invention.
  • FIG. 18 is a partial single-line diagram illustrating an further alternate embodiment of the center switch circuitry of the present invention
  • FIG. 19 is a partial single-line diagram illustrating an alternate embodiment of the center switch circuitry of the present invention
  • FIG. 20 is a partial single-line diagram illustrating an additional alternate embodiment of the center switch circuitry of the present invention
  • FIG. 21 is a partial single-line diagram illustrating an alternate embodiment of the center switch circuitry of the present invention
  • FIG. 22 is a partial single-line diagram illustrating a further alternate embodiment of the center switch circuitry of the present invention
  • FIG. 23 is a partial single-line diagram illustrating an alternate embodiment of the center switch circuitry of the present invention
  • FIG. 24 is a partial single-line diagram illustrating an additional alternate embodiment of the center switch circuitry of the present invention.
  • FIG. 25 is a partial single-line diagram illustrating an alternate embodiment of the center switch circuitry of the present invention.
  • FIG. 26 is a block diagrammatic, single-line schematic illustration of a typical uninterruptible power supply.
  • FIG. 1 illustrates one double- conversion inverter 100 coupled to a single load 102
  • FIG. 1 illustrates one double- conversion inverter 100 coupled to a single load 102
  • embodiments of the UPS system of the present invention may utilize multiple power modules having similar internal topology as that illustrated in FIG. 1 coupled in parallel to supply the connected load 102.
  • the following will provide a description of only a single double-conversion inverter 100.
  • such description is made by way of illustration not by way of limitation. Further, aspects of the present invention are applicable to other inverter designs as will become apparent from the following description.
  • a UPS constructed in accordance with the teachings of the present invention includes an input for the AC utility line voltage 104 and an input for the electric power storage batteries 106.
  • an input select circuit 108 may be utilized to supply the appropriate power input 104, 106 to the inverter circuitry.
  • This inverter circuitry includes multiple electronic switching elements 110, 112, 114, and 116.
  • the inverter circuitry also includes DC bus capacitors 118, 120 that are coupled through a center switch circuit 122 to the neutral or return line 124. This center switch circuit 122 controllably associates and disassociates the DC bus capacitors 118, 120 from the neutral connection 124.
  • this circuitry 122 provides significant advantages over prior design that utilize a permanent connection from the bus capacitors 118, 120 to the neutral connection 124, such as that illustrated in FIG. 26. While separate bypass and fault isolation circuitry may be included in the UPS of the present invention, operation of the center switch circuit 122 renders such circuitry superfluous. As a result, the UPS design of the present invention may operate in a high efficiency mode, may soft-charge the bus capacitors 118, 120, and may properly isolate a failed UPS module in a multiple UPS or modular UPS system without the need for the additional circuitry required by the prior designs.
  • FIG. 2 illustrates a single-line schematic diagram of an embodiment of a UPS (or a single UPS power module for use in a modular UPS system).
  • the input selected circuit 108 comprises two relays 126, 128 through an in-line inductor 130, the function of which will be described in detail below.
  • Steering diodes 132, 134 ensure proper power flow through the inverter circuitry 100 in association with diodes 136, 138, 140, 142, 144, and 146.
  • the switching elements 110, 112, 114 and 116 may utilize single or multiple- paralleled semiconductor switches as shown in this detailed single-line schematic.
  • the DC bus capacitors 118, 120 may utilize single or multiple-paralleled capacitors as appropriate to provide the required energy storage for the operating characteristics of the UPS.
  • Output waveform conditioning is provided by an output inductor 148 and filter capacitor 150.
  • the center switch circuit 122 comprises a single active semiconductor switch 152 and a plurality of passive devices, such as diodes 154, 156, 158, 160, 162, and 164.
  • the coupling to the individual DC bus capacitors 118, 120 are provided by the diode pairs 158/160 and 154/156, respectively.
  • the coupling to the neutral 124 is provided by the diode pair 162/164.
  • the embodiment of FIG. 2 also includes switching element 166 that is used in conjunction with diode 146 and inductor 168 to provide negative bus charging of capacitors 120 from the battery input 106 as will be discussed more fully below.
  • the first mode of operation is the high efficiency mode of operation of the UPS circuit 100.
  • the convention utilized to illustrate power flow in these figures is a darkened line through the appropriate elements of the circuitry through which power is flowing.
  • the high efficiency mode of operation which is appropriate during periods of normal utility line availability, provides very high efficiency operation in the range of 95% efficient without the use of external bypass circuitry.
  • the power flow during the positive half-cycle of the input AC line voltage flows through relay 126, inductor 130, diode 132, diode 136, switching element 112, output inductors 148 and capacitor 150, through the connected load 102, to the return 124.
  • This power flow is enabled without the use of an external bypass circuitry by turning off the semiconductor switch 152 of the center switch circuit 122 to disassociate the neutral connection from the DC bus capacitors 118, 120. With this switching element 152 turned off, the DC bus capacitors 118, 120 are effectively removed from the circuit allowing the positive DC bus 170 to carry the positive half-cycle of an AC voltage waveform.
  • switch 112 is turned off and switch 116 is turned on.
  • the power flow is from the neutral 124, through the load 102, the output capacitor 150, and inductors 148, down through switching element 116, through steering diodes 138 and 134, back through inductor 130 and relay 126 to line 104.
  • very little losses are realized, on the order of the losses associated with the external bypass circuitry of typical inverter designs, without the resultant cost, thermal management, size, and reliability issues existing with such an external bypass circuit.
  • the switching device 152 of the center switch circuit 122 may be pulse width modulated to establish a charge on the capacitors 118, 120. This provides soft charging of these bus capacitors 118, 120 during normal AC line voltage operation so that the UPS may immediately switch from the high efficiency mode to the double- conversion mode of operation or to the battery mode of operation upon degradation or loss of the AC line input from the utility. Such transition occurs without any interruption or loss of power to the connected loads 102 with the present invention.
  • the pulse width modulation of the switching element 152 also ensures that the AC waveform is not disrupted in any appreciable fashion during this charging operation. Turning now to Figs.
  • the power flow during the double- conversion mode of operation of the UPS 100 will now be discussed.
  • the input voltage is conditioned from the utility AC line input 104, and the output power supplied to the connected loads 102 is regenerated from the dual DC bus 170, 172.
  • FIG. 4a the power flow for charging the input inductor 130 during this double-conversion mode is illustrated.
  • the control for this input (boost) converter is such that the switching devices are pulse width modulated in a manner such that the UPS 100 draws a current in the same wave shape as the voltage waveform. If, for example, the voltage waveform is a normal sinusoid, the current (once filtered) is drawn sinusoidally as well.
  • this circuitry presents a unity power factor to the utility line 104.
  • power flows through the relay 126, input inductor 130, steering diode 132, through closed switches 110, and back to neutral 124.
  • the semiconductor switches 110 need only be closed for a few microseconds to allow the current to build up in the inductor 130.
  • the charging of the inductor 130 is necessary to provide boost conversion of the utility line input voltage 104 to the DC bus. In this way, the inverter may construct an output AC waveform of proper amplitude for use by the load 102.
  • inductor 130 Once the inductor 130 has been charged, its energy is then transferred to the DC bus capacitors 118 as is illustrated in FIG. 4b. This energy discharge from the input inductor 130 into the capacitor bank 118 is accomplished by turning off switches 110 and turning on switch 152 of the center switch circuit 122. Since the current through the inductor cannot change instantaneously, current continues to flow through this inductor 130 once the switches 110 have been opened. To aid in the understanding of the operation of FIG. 4b it is helpful to consider inductor 130 as a current source. That is, while initially in FIG. 4a the polarity across the inductor 130 represented a voltage drop, once the switches 110 have been turned off the polarity of the input inductor 130 changes to that illustrated in FIG. 4b.
  • the voltage potential on inductor 130 adds to the line voltage from the utility line input 104.
  • This higher potential overcomes the blocking provided by diode 136, causing power to flow in the path from the input 104 through relay 126 and from inductor 130, through diodes 132 and 136, into capacitors 118, through diode 158, through switching element 152, and through diode 164 to neutral.
  • the switching device 152 of the center switch circuit 122 remains on continuously.
  • FIG. 4c illustrates the typical power flow of the output stage during this double-conversion mode of operation.
  • the switching element 112 is modulated such that it provides a pulse train of varying duty cycle to generate the positive half-cycle of the output voltage waveform.
  • This pulse train is then filtered by the output inductors 148 and capacitor 150 to present a sine wave to the load 102.
  • the power flow for this positive half- cycle flows from the DC bus capacitors 118, through the pulse width modulated switching element 112, filtered by inductors 148 and capacitor 150, through load 102, and back to the bus capacitors 118 through the center switching circuit 122.
  • the power flow through the center switching circuit 122 takes place through diode 162, through switching element 152 (which remains in the on state), and through diode 160.
  • the negative half of the sine wave output is generated in like manner utilizing pulse width modulation of switching element 116.
  • the switching element 152 of the center switch circuitry 122 remains in the on state. Operation of the UPS circuitry 100 of the present invention in a DC
  • boost converter mode will now be illustrated with reference to Figs. 5a-5d. While one skilled in the art will recognize that a boost mode of operation is not required if an appropriate battery voltage is established by the battery 174, requiring such a high battery voltage is often not practical in commercial applications. Therefore, the boost DC conversion mode allows the use of a much smaller battery pack having an output voltage of, for example, 120 volts DC.
  • the operation of the UPS circuitry 100 of the present invention is capable of boosting the battery voltage to a preferred +/-400 volts DC required by the output stage to generate a typical output voltage waveform for the connected loads 102.
  • the power flow for this DC boost-converter mode of operation begins by opening relay 126 and closing relay 128. Additionally, switching element 110 is turned on, which allows current to build through the input inductor 130 through diode 132. As is illustrated by the polarity markings on the inductor 130 in this initial phase of this operation, the inductor appears as a voltage drop in the series circuit.
  • the switching element 110 When the inductor is charged sufficiently or the current limit is reached, the switching element 110 is opened as illustrated in FIG. 5b.
  • the input inductor 130 becomes a current source (note polarity symbols) that adds to the battery potential.
  • diodes 132 and 136 become forward biased and conduct power into the capacitor 118.
  • the switching element 152 of the center switching circuit 122 is closed upon opening of the switching element 110.
  • current flows from the battery 174 through relay 128, and from inductor 130 through diodes 132 and 136 to the DC bus capacitor 118. From the capacitor 118 the current flows through diode 158, through closed switching device 152, and through diode 164 back to neutral.
  • the negative DC bus capacitors 120 In order to charge the negative DC bus capacitors 120 from the battery
  • switching element 166 is turned on to allow current flow through diode 146 and inductor 168 as illustrated in FIG. 5c. Once the inductor 168 is sufficiently charged or current limit is reached, switching element 166 is opened and the inductor 168 becomes a source as illustrated in FIG. 5d. Since the positive side of inductor 168 is tied to neutral 124 the more negative end of inductor 168 goes negative from neutral. The power flow is then from inductor 168, through diode 162, through switching element 152, through diode 156, through negative bus capacitors 120, and through diode 140. Once the bus capacitors 118, 120 are charged, the output waveform generation proceeds as discussed above with reference to FIG. 4c.
  • FIG. 6a illustrates a single-line schematic diagram of a three- phase in/one-phase out embodiment of the UPS 100 of the present invention.
  • a center switching circuit 122 is provided to controllably associate/disassociate the DC bus capacitors 118, 120 from the neutral 124 of the UPS 100. Operation of this three-phase in/one- phase out embodiment proceeds essentially as discussed above for the various modes of operation.
  • the input utility voltage on line 104 a flows through relay 176 and inductor 130 a .
  • this waveform is conducted through diode 132 a , and through diode 134 a on the negative half-cycle.
  • the utility line voltage on line 104 b conducts through inductor 130 b .
  • the waveform conducts through diode 132 b , and through diode 134 b on its negative half-cycle.
  • the utility line voltage on line 104 c will conduct through relay 178 and inductor 130 c .
  • switching element 110 When switching element 110 opens, current continues to flow from the input line through the respective input inductors and diodes, through diode 136, and through DC bus capacitor 118 to deliver a charge thereto. The current continues to flow through diode 158, switching element 152, and diode 164 of the center switch circuit 122 to neutral 124.
  • switching element 114 To store energy in the input inductors 130 a -130 c during the negative half-cycle of each of the utility line input to voltages 104 a -104 c , switching element 114 is closed. Current will then flow from the neutral 124 through diode 182 and switch element 114, through each of the respective diodes 134 a - 134 c and the respective input inductors 130 a -130 c , to each of the input utility lines 104 a -104 c as each becomes negative. When switch 114 opens, current continues to flow through the respective input inductors 130 a -130 c and diodes 134 a -134 c .
  • switches 110 and 114 are switched at a frequency of approximately 10 kHz or higher. The switching of elements 110-114 can be controlled such that power factor correction of the current can be achieved on all three input phases.
  • Boost-converter operation when this embodiment is utilizing the battery 174 to power the output is achieved by switching input relays 176 and 180 from the line to the battery position.
  • Relay 178 also switches to connect inductor 130 c to the neutral line 124.
  • relay 180 is switched to couple the positive terminal of the battery 174 to the collector of switch element 114.
  • a charge is maintained on DC bus capacitor 118 by controlling switching element 110, although charge maintained on the negative DC bus capacitor 120 is maintained by controlling switching element 114 in a manner similar to that described above. That is, as switching element 110 turns on current flows from the battery 174, through input inductor 130 a and diode 132 a , through switching element 110, and back to the battery.
  • the switching element 114 To charge the negative DC bus capacitor 120, the switching element 114 is turned on. Current then flows from the battery 174 through relay 180, through switch 114, through diode 134 c and inductor 130 0 , through relay 178, and back to the battery. As may be appreciated, energy is stored in the inductor 130 c during this period. When switching element 114 is turned off, current continues to flow through inductor 130 c , through relay 178, through diode 162 and closed switching element 152 of the center switching circuit 122. Current continues to flow through diode 156 and through capacitor 120, through diode 138 and diode 134 c back to the input inductor 130 c . This power flow transfers energy to the negative DC bus capacitor 120 for subsequent utilization in the generation of the output to voltage waveform to supply the connected loads 102.
  • the energy stored in the DC bus capacitors 118, 120 is converted to a sine wave voltage output to the connected load 102 through output inductor 148 and capacitor 150.
  • Switching elements 112 and 116 are pulse width modulated at frequencies of approximately 10 kHz or higher to construct such an output waveform.
  • inductor 148 and capacitor 150 provide filtering of the PWM output signal to smooth the sine wave output voltage.
  • switching element 112 turns on, current flows from the DC bus capacitor 118 through this switching element 112, through inductor 148 and capacitor 150 and the parallel connected load 102, through diode 162 and closed switching element 152, and through diode 160 back to capacitor 118.
  • the switching element 116 is turned on so that current may flow from the DC bus capacitor 120, through diode 154, closed switching element 152, and diode 164, through capacitor 150 and the parallel coupled load 102, through inductor 148, through closed switching element 116, and back to capacitor 120.
  • switching element 116 turns off, current continues to flow through the inductor 148, which causes diode 142 to conduct.
  • Current now flows from inductor 148, through diode 142, through capacitor 118, through diode 158 in closed switching element 152, through diode 164, and through capacitor 150 and the parallel coupled load 102.
  • switching element 112 is off, switching element 116 is turned on to provide a proper current path with reactive load.
  • the modulation of switching element 116 produces the negative half-cycle of the output AC voltage waveform.
  • FIG. 6b An alternate embodiment of a three input phase/one output phase topology is illustrated in FIG. 6b.
  • the center switch topology is maintained to selectively associate/disassociate the DC bus capacitors 118, 120 from the neutral connection 124 as described above.
  • the input stage of this embodiment differs somewhat from the embodiment illustrated in FIG. 6a in that switching pairs 110 a /l 14 a , 110 b /l 14 b , and 110 c /l 14 c are included for each of the individual three phase inputs 104 a , 104 b , and 104 c , respectively.
  • the input phase-switching through relays 176, 178, 180, and 182 to control and isolate each of the various operating modes occurs in similar fashion to that described above.
  • FIG. 7 illustrates a further embodiment of the UPS of the present invention having three input phases and generating three output phases for three-phase connected loads.
  • the input stage operation of this embodiment of the present invention is similar to that described for the embodiment illustrated in FIG. 6a also having three input phases.
  • the output voltage waveform generation for each of the output phases also utilizes a similar control strategy for its generation. Therefore, the various details of the operation of this circuit will not be described in the interests of brevity. Suffice it to say that the pulse width modulation of the output switch pairs for each output phase may be individually controlled to supply separate individual outputs, or may be coordinated to provide a three-phase output voltage waveform.
  • the UPS of the present invention has universal applicability to the various power distribution specifications used throughout the world. It can be used as a 120 volt system, a 120/240 split-phase system, or a 120/208 volt UPS.
  • the UPS of the present invention also can be used in Japanese utility systems operating at 100/200 volts.
  • the embodiment of the present invention illustrated in FIG. 8 is applicable.
  • this embodiment also is capable of operating in various modes. In a high efficiency mode of operation, minimal losses are incurred as the UPS is not correcting power factor (neither regulation nor power factor correction) and the switching devices are not switching.
  • the input voltage is conditioned and the output power is regulated from a dual DC bus as shown in FIG. 8.
  • the boost conversion mode of operation when relying on the battery 174 is also available and will be discussed below.
  • phase shifted input/output In 120 volt use the two input line voltages 200, 202 as well as the two output voltages 204, 206 are operated in parallel. In the phase-shift mode they are effectively in series, and run either 120 degrees, 180 degrees, or 240 degrees out of phase with each other. Running either 120 degrees or 240 degrees apart gives the 120/208 or 127/220 voltages by vector addition. Operating 180 degrees out of phase gives the split-phase 120/240, 115/230, 110/220, or 100/200 volt outputs. Regardless of the mode of operation, note that the neutral 208 is carried through always.
  • the first utility line input 200 is coupled through a relay 210 to inductors 212, 214.
  • the other side of inductor 212 is coupled through diode 216 to switching device 218 and its anti-parallel diode 220.
  • Switch 218 is coupled through output inductor 222 and filter capacitor 224 to its parallel coupled load 226.
  • inductor 214 is coupled through diode 228 to switching device 230 and its anti-parallel diode 232.
  • This switch 230 is also coupled through an output inductor 234 and an associated filter capacitor 236 to its parallel coupled load 238.
  • a switching element 240 and its anti- parallel connected diode 242 are coupled to the positive rail 244 of a first DC bus.
  • DC bus capacitor 246 is also coupled to the positive rail 244, and to a center switch circuit 122 as described above.
  • a second switching device 248 and its anti-parallel connected diode 250 are coupled to the positive rail 252 of the second DC bus.
  • a second DC bus capacitor 254 is also coupled to the positive rail 252 of the second DC bus, and to the center switch circuit 122 as illustrated.
  • Switching device 256 and its anti-parallel diode 258 are coupled to the negative rail 260 of the first DC bus, as is DC bus capacitor 262.
  • This DC bus capacitor 262 is also coupled to the center switch circuit 122 as illustrated.
  • Switching device 264 and its anti-parallel connected diode 266 are coupled to the negative rail 268 of the second DC bus.
  • DC bus capacitor 270 is also coupled between the negative rail 262 of the second DC bus and to the center switch circuit 122 as illustrated.
  • the inductor 214 is coupled through switching element 272 and diode 274 to the node coupling switching devices 240 and 256.
  • the second line voltage input 202 is coupled through relay 276 to inductor 278.
  • Steering diode 280 couples the negative rail 268 of the second DC bus to inductor 278.
  • Switching elements 282 and 286, in association with their anti-parallel connected diodes 284 and 288 are coupled to output inductors 234 and 222 and to their respective negative rail DC busses 260, 268.
  • switching elements 248, 230, 256, and 282 are always on, i.e., no switching of these devices is occurring.
  • the utility voltage on line 2 transfers power to its connected load through relay 276, inductor 278, switch 256, diode 284, inductor 222, and capacitor 224, to its parallel connected load 226, and back to neutral 208.
  • line 202 traverses its negative half-cycle, power flows from the neutral 208 through its connected load 226 in the parallel capacitor 224, through inductor 222, switching element 282, diode 258, inductor 278, relay 276, and back to the line 202.
  • switching element 152 of center switch circuitry 122 is off to disconnect the DC bus capacitors 254, 246, 270, 262 from the power path.
  • switching element 152 may be pulse width modulated during the high efficiency mode of operation to soft charge the DC bus capacitors 254, 246, 270, 262. This will assure that these capacitors are ready to source current for mode changing or line transfer if, and immediately when, required.
  • the inverter switches are not transitioned during the high efficiency mode of operation as they were in the embodiment illustrated in FIG. 2.
  • power flow for both the positive and negative half-cycles are accomplished through the output switching element and its anti-parallel connected diode. This allows the same power path to be utilized for both the positive and negative half-cycle of the utility line voltage, further increasing the efficiency of operation in this mode.
  • switching element 152 of the center switch circuitry 122 is turned on to afford the capacitors a discharge path to neutral.
  • the actual voltage will be perhaps 2 volts off from neutral as there are voltage drops associated with the diodes and the switching element 152.
  • the switching elements are pulse width modulated in a manner that the UPS draws a current in the same wave shape as the voltage. If, for example, the voltage wave shape is a normal sinusoid, the current (when filtered) is drawn sinusoidally as well. When the input is the battery, current is drawn DC. In this way, a unitary power factor is presented to the line, with minimal harmonic currents. Turning to FIG.
  • power flow is illustrated to charge inductor 212 to provide a battery boost for the positive bus.
  • power from battery 174 is provided to inductor 212 and through relay 210, which is switched to make the coupling therebetween.
  • the power continues to flow through switching element 264, through capacitor 270 (which discharges slightly in the process), through diode 154, through switching element 152 and diode 164, back to neutral.
  • the switching element 264 need only be closed for a few microseconds at a time. When switching element 264 is opened, as illustrated in FIG. 10b inductor 212 becomes a current source.
  • this inductor 212 As the polarity of this inductor 212 reverses, the current flow path is through the inductor 212, through diodes 250 and 216, and into, respectively, bus capacitors 254 and 246. The current continues to flow through diode 158, switching element 152, diode 164, through battery 174 and back to inductor 212 through relay 210.
  • FIG. 10c illustrates the charging of inductor 278.
  • current flow from battery 174 through relay 210 continues through inductor 214 via switching element 272, diode 274, inductor 278, and relay 276.
  • inductor 214 presents only a negligible drop since it is a small inductor for noise filtration.
  • diode 228 does clamp its energy upon turn-off of switching element 272.
  • inductor 278 becomes a current source as illustrated in FIG. lOd.
  • the polarity of inductor 278 switches and provides power flow through diode 162, switching element 152, diode 156, and negative DC bus capacitors 270 and 262. Power flow continues through diodes 258 and 280 back to inductor 278. This results in the charging of the negative DC bus capacitors 270 and 262.
  • FIG. 1 la illustrates the power flow for the AC front end during line operation to charge inductor 212. Since operation of the UPS of the present invention under different line phases and polarities is similar, the following discussion will describe only the operation of the present invention on the positive half-cycle of the utility line voltage 200. Operation with other polarities and phases follow the same scheme with mirrored devices.
  • inductor 212 On the positive half-cycle of line voltage 200, power flows through relay 210 and through inductor 212. The current flow continues through switching device 264, DC bus capacitor 270 (which discharges slightly), and continues through diode 154, switching element 152, diode 164, and returns to neutral 208. When transistor 264 turns off, inductor 212 becomes a current source as is illustrated in FIG. 1 lb. As such, the current from inductor 212 supplements the line current.
  • FIG. l ie illustrates the operation of the output switches once the DC bus capacitors have been charged as described above.
  • switching element 230 In operation, at zero cross (the start of the half-cycle) all switches are off. Initially, switching element 230 is pulsed on very briefly. These pulses are filtered by inductor 234 and capacitor 236. After a brief time, switching element 230 is pulsed again but with a longer on time. The filtered voltage rises a bit higher. Subsequent cycles have a longer and longer on times, with the result of the higher output voltage. A highest output voltage is a result of the longest on time, which occurs at 90 degrees. At this point, the duty cycle is decreased, causing the output voltage to likewise decrease. As will be recognized by those skilled in the art, switching element 286 provides like operation for the negative half-cycle.
  • the second section comprising switching elements 218 and 282 (along with their associated circuitry), provides the second phase of the output.
  • operation is identical to that of the first phase.
  • the two outputs can be run together (in phase) for full power output at 100-110-120 volts, phase shifted 120 degrees for 120-208 volts (127/220), or phase shifted 180 degrees out of phase for 100/200, 110/220, 115/230, or 120/240 volt outputs.
  • FIG. 12 illustrates a further embodiment of the present invention that utilizes a double bus for split-phase operation.
  • this embodiment does not include a battery input, and is therefore used only in a high efficiency mode or in a line conditioning mode to supply output power from the utility input 324, 326.
  • Operation of this embodiment in the high efficiency mode provides power flow from the utility line input 324, through inductor 330, through diodes 332, 334, through output switching device 316, output inductor 336 and filter capacitor 338, to neutral 328.
  • power flow is from the neutral 328, through filter elements 338, 336, through switching element 318, diodes 340, 342, through inductor 330, and back to the line input 324.
  • output switches 316, 318 are switched at a rate equal to the utility line voltage in this high efficiency mode of operation for each respective half-cycle of the utility line voltage waveform.
  • switching element 152 of the center switch circuitry 122 remains off during the high efficiency mode of operation.
  • this switching element 152 may be pulse width modulated to provide soft charging of the DC bus capacitors 308, 310, 312, 314 so that the mode of operation of this embodiment may be switched from the high efficiency mode to the line conditioning mode without loss in output.
  • This line conditioning mode of operation is similar to that described above for the double-conversion mode of the prior embodiments, and therefore will not be discussed here in the interests of brevity.
  • FIG. 13 illustrates yet a further embodiment of the present invention similar to that illustrated in FIG. 12, but including a boost conversion mode of operation and a battery input for full UPS functionality.
  • this embodiment includes switching elements 350 and 352 which may be utilized for the boost conversion of the DC battery voltage. It is also noted that this embodiment includes separate diode pairs 158/160, 154/156, 300/302, and 304/306 for each of the individual DC bus capacitors 308, 312, 314, and 310.
  • FIG. 14 illustrates yet a further embodiment of the present invention utilizing three input phases and providing three output phases, with the capability of providing boost-converter operation for supplying the output power from the battery to provide full UPS functionality.
  • This embodiment clearly illustrates the scalability of the present invention from single to multiple phases both on the input and the output. Operation of this circuit will be foregone in the interests of brevity and in view of the prior descriptions of the previous embodiments, whose application to this embodiment should now be recognized by those skilled in the art.
  • the center switch circuitry 122 also includes in this embodiment individual diode pairs for each of the DC bus capacitors in addition to the switching element 152 and diodes 162 and 164.
  • switching element 152 is illustrated as an insulated gate bipolar transistor (IGBT) it should be noted that this device may utilize other devices such as mosfets, transistors, relays, etc. Also as with the previous embodiment, operation in the boost-converter mode is facilitated by the transition of relays 360, 362, 364, 366, 368, and 370.
  • IGBT insulated gate bipolar transistor
  • FIG. 15 illustrates a further embodiment of the present invention utilizing multiple center switches to provide individual control of the current from the separate energy sources (e.g., capacitors).
  • center switching circuitry 400 comprising diodes 402, 404, 406, and 408, and switching element 410 provides the control of the current flow into and out of the DC bus capacitor 412.
  • center switch 414 provides individual control of DC bus capacitor 416 through diodes 418, 420, 422, and 424, in addition to switching element 426. Operation of this embodiment of the present invention is similar to that described above, and provides operation in each of the UPS modes previously described.
  • FIG. 16 illustrates a further embodiment of the present invention providing full UPS operability in a similar manner to those embodiments described above.
  • a relay 450 is added to provide a bypass mode of operation. This relay is closed to allow the UPS to operate in the bypass mode to provide true n+1 redundancy operation or multiple module operation where the output of the modules are running in parallel. If one of the modules fails and overloads a second good module, the relay 450 is closed on the good or properly operating module to prevent propagation of the failure to the good module. The module operates in this mode until the bad module is isolated. It should be recognized by those skilled in the art that such a bypass relay 450 may be incorporated in the various other embodiments of the invention as desired. Operation in the other modes are as described above with the prior embodiments.
  • FIG. 17 presents an alternate embodiment for this circuitry applied to a basic two capacitor bus topology, which is common in most multi-conversion UPS systems.
  • power to charge the capacitors and power from the capacitors is from the positive and negative DC busses, common to the neutral.
  • a center switch capacitor isolation topology is utilized having only two diodes 452 and 454 with a switching element 456.
  • the power flow in this embodiment is such that when the switch is open, the bus capacitors 458, 460 each charge from the positive and negative busses, through diodes 452 and 454 to neutral. If power is to be drawn from the capacitors 458, 460, the diodes effectively block current flow, effectively isolating the capacitors from the circuit.
  • the positive (or negative) discharge path is from neutral, through diode 454 (or diode 452 for the negative discharge), through capacitor 458 (460) into the positive (or negative) bus.
  • diode 454 or diode 452 for the negative discharge
  • capacitor 458 460
  • One particular advantage, to this topology is the very low voltage drops throughout the system, and the small number of components required.
  • Figs. 18 and 19 illustrate alternate topologies of the center switching circuit that utilize relays, either individual relays 462 and 464 illustrated in FIG. 18 or a common relay 466 illustrated in FIG. 19.
  • the relay open the capacitors are out of the circuit. Closing the relay includes the capacitor in the circuit.
  • the prime advantage of such a topology for the center switch circuit is that there is almost no power lost through the switching device. The voltage drop across the contacts of the relays is nearly negligible, however the coil wattage does utilize additional power. Since mechanical relays typically take 7 to 25 milliseconds to actuate, during which time the capacitors are not available to supply power, this topology may find best applicability where such response delays are tolerable.
  • FIG. 20 illustrates a further embodiment of the center switching circuitry of the present invention that utilizes an additional bi-directional Zener clamping device 468, which conducts at a given voltage.
  • the purpose of this device 468 is to allow the capacitors 458, 460 to accept transient energy spikes that exceed the normal bus voltage. For example, if the bus was charged to +/- 200 volts (400 volts included), the additional of a 250 volt bidirectional Zener diode 468 would allow the capacitors 458, 460 to remain disconnected at the normal bus voltage, but come into play if a surge greater than 250 volts were impressed on the bus lines.
  • the inclusion of this bi-directional device 468 may be included to any topology of the center switch circuit where such functionality is desired.
  • FIG. 21 illustrates the addition of pre-charging resistors 470, 472 to the relay topology of FIG. 19.
  • the purpose of these resistors is to allow the capacitors 458, 460 to be (slowly) brought up to charge in a controlled-current manner. It will be recognized by those skilled in the art that the time constant provided by this circuitry is an exponential function, directly proportional to the instantaneous current. Therefore, the capacitors are made available to supply power after a brief, calculable period of charge.
  • the addition of these pre-charge resistors are not limited to the relay embodiment illustrated in this figure, but may be utilized in any topology where such controlled current charging is desired.
  • FIG. 22 is identical in theory to the embodiment of the center switch circuit illustrated in FIG. 17 with the switching element 456 being replaced by a MOSFET transistor.
  • the advantage of utilizing such a device as that illustrated in FIG. 22 over mechanical means lies in the speed of the MOSFET, which is essentially instantaneous. This allows the capacitors to connect with no time lag, meaning that there is no time when the load is without available power. Additionally, the MOSFET 474 can be modulated by a rapid series of ever widening pulses, allowing a controlled charge to be applied to the capacitors.
  • FIG. 23 provides a similar topology with the replacement of the MOSFET 474 with an IGBT 476. The advantage presented by this embodiment is the lower power loss through the IGBT 476 than with the MOSFET 474.
  • FIG. 24 presents the embodiment of FIG. 23 with the addition of a soft charge resistor 478. As described above, the addition of this soft charge resistor 478 allows the soft charging of the capacitors 458, 460 through a known time constant function.
  • FIG. 25 adds the addition of the bi-directional Zener device 480 to the embodiment of FIG. 24 to provide the functionality described above associated with the use of such a device.

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Abstract

L'invention concerne un circuit de commutation central et un convertisseur continu-alternatif, ainsi qu'une alimentation électrique sans coupure les utilisant. Le circuit de commutation central active et désactive sélectivement le transit de la puissance vers et depuis les condensateurs à barres omnibus d'un convertisseur continu-alternatif ou de l'alimentation sans coupure. Ainsi, le circuit de commutation central élimine efficacement les condensateurs à barre omnibus du circuit. Ceci permet au convertisseur ou à l'UPS de fonctionner dans un mode de fonctionnement hautement efficace, une tension composée d'entrée pouvant être acheminée essentiellement sans compensation jusqu'à la sortie, lorsque ledit circuit est ouvert. La modulation du circuit durant ce mode de fonctionnement permet un chargement souple des condensateurs à barres omnibus, de telle qu'ils puissent recevoir le courant source en mode conversion double ou amplification du courant continu en cas de dégradation ou de perte de la tension composée. Pour assurer l'alimentation électrique de sortie depuis les condensateurs à barres omnibus, le circuit de commutation central est fermé de manière à associer ces condensateurs au conducteur neutre. La localisation des incidents est assurée pendant le fonctionnement par ouverture du circuit de commutation central, de manière à empêcher le transit de la puissance depuis les condensateurs à barres omnibus.
PCT/US2000/040808 2000-09-01 2000-09-01 Convertisseur continu-alternatif pourvu d'un commutateur central et alimentation electrique sans coupure utilisant celui-ci WO2002021663A1 (fr)

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AU2000280373A AU2000280373A1 (en) 2000-09-01 2000-09-01 Inverter having center switch and uninterruptible power supply implementing same
PCT/US2000/040808 WO2002021663A1 (fr) 2000-09-01 2000-09-01 Convertisseur continu-alternatif pourvu d'un commutateur central et alimentation electrique sans coupure utilisant celui-ci

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EP1732201A3 (fr) * 2005-06-06 2017-03-22 ABB Oy Procédé et dispositif pour charger les condensateurs d'un circuit intermédiaire de tension continue d'un convertisseur de fréquence
CN111262330A (zh) * 2018-11-30 2020-06-09 施耐德电气It公司 三相ups总线平衡器
IT202000025114A1 (it) * 2020-10-23 2022-04-23 Mo S A I C Motion System And Information Control S R L Convertitore statico di potenza trifase/monofase

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1732201A3 (fr) * 2005-06-06 2017-03-22 ABB Oy Procédé et dispositif pour charger les condensateurs d'un circuit intermédiaire de tension continue d'un convertisseur de fréquence
CN111262330A (zh) * 2018-11-30 2020-06-09 施耐德电气It公司 三相ups总线平衡器
CN111262330B (zh) * 2018-11-30 2023-10-27 施耐德电气It公司 三相ups总线平衡器
IT202000025114A1 (it) * 2020-10-23 2022-04-23 Mo S A I C Motion System And Information Control S R L Convertitore statico di potenza trifase/monofase

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