Ups and method of operating an ups

Abstract

An uninterruptible power supply (UPS) includes an input, a backup power input, a positive DC bus and a negative DC bus, a converter, and at least one controller. The converter includes a first inductor, a second inductor, a first converter switch coupling the first inductor to a neutral connection, a second converter switch coupling the second inductor to the positive DC bus, a third converter switch coupling the second inductor to the negative DC bus, and a fourth converter switch coupling the second inductor to the backup power input. The at least one controller is configured to: operate the converter in a backup operating mode in response to determining that acceptable AC power is not available at the input; operate the first converter switch in the backup operating mode to provide DC power derived from the backup DC power to the positive DC bus via the first inductor; operate the fourth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the negative DC bus via the second inductor.

Description

[0001] This application is a divisional application of the application for patent entitled “AC Switch PFC with Integrated Charger and DC-DC for Online UPS System” with application number 202210669425.6 and filing date 2022-06-14. TECHNICAL FIELD

[0002] Embodiments of the present disclosure generally relate to power conversion, and more specifically, to AC-DC power conversion in an uninterruptible power supply. BACKGROUND

[0003] An uninterruptible power supply (UPS) is used to provide backup power to electrical equipment or loads in the event of a failure of the main power supply or mains. Typical loads include computer systems, but other loads such as heating / cooling / ventilation systems, lighting systems, network switches and routers, and security data center management systems can also receive backup power between 1 and 20 kVA for hours. SUMMARY

[0004] At least one aspect of the present disclosure relates to an uninterruptible power supply (UPS). The UPS includes an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and provide DC power to the backup power source for charging, a positive DC bus and a negative DC bus galvanically coupled to the backup power input, and a converter coupled to the input, the backup power input, and the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, and a third converter switch configured to couple the second inductor to the negative DC bus, wherein the UPS is voltage-frequency independent.

[0005] In one embodiment, the UPS includes a controller coupled to the converter and configured to operate the first converter switch to provide DC power derived from the input AC power to the positive DC bus via the first inductor and operate at least one of the second converter switch or the third converter switch to provide DC power derived from at least one of the positive DC bus or the negative DC bus to the backup power input via the second inductor during a positive half cycle of the input AC voltage in a first operating mode, and operate the first converter switch to provide DC power derived from the input AC power to the negative DC bus via the first inductor and operate at least one of the second converter switch or the third converter switch to provide DC power derived from at least one of the positive DC bus or the negative DC bus to the backup power input via the second inductor during a negative half cycle of the input AC voltage in the first operating mode. In some embodiments, the UPS includes an input selection circuit configured to couple the converter to the input during the first operating mode and to the backup power input during a second operating mode. In various embodiments, the controller is configured to monitor the input AC power, operate the UPS in the first operating mode in response to determining that the input AC power is acceptable, and operate the UPS in the second operating mode in response to determining that the input AC power is not acceptable. In certain embodiments, the backup power input is configured to receive backup DC power from a backup power source, and the converter further includes a fourth converter switch configured to couple the second inductor to the backup power input.

[0006] In some embodiments, the controller is configured to operate the first converter switch to provide DC power derived from the input AC power to the positive DC bus via the first inductor in the first operating mode, and to operate the fourth converter switch to provide DC power derived from the input AC power to the negative DC bus via the second inductor in the first operating mode. In one embodiment, the converter further includes a fifth converter switch configured to couple the second inductor to the neutral connection, and the controller is configured to operate the fifth converter switch to provide DC power derived from the input AC power to the positive DC bus via the second inductor in the first operating mode, and to operate the fourth converter switch to provide DC power derived from the input AC power to the negative DC bus via the second inductor in the first operating mode. In one embodiment, the first converter switch is a bidirectional switch circuit including a first switch and a second switch coupled in series. In certain embodiments, the converter includes a first diode coupled between the first converter switch and the positive DC bus, a second diode coupled between the first converter switch and the negative DC bus, the fourth converter switch configured to couple the second inductor to the input AC power, and the fifth converter switch configured to couple the second inductor to the neutral connection. In various embodiments, the first inductor, the first switch of the first converter switch, the body diode of the second switch of the first converter switch, and the first diode are configured to operate as a boost converter in the first operating mode during a positive half cycle of the input AC voltage to provide DC power derived from the input AC power to the positive DC bus.

[0007] In some embodiments, the second inductor, the third converter switch, and the body diode of the fourth converter switch are configured to operate as a buck-boost converter in the first operating mode to provide DC power derived from the negative DC bus to the input AC power. In one embodiment, the first inductor, the second switch of the first converter switch, the body diode of the first switch of the first converter switch, and the second diode are configured to operate as a boost converter in the first operating mode during a negative half cycle of the input AC voltage to provide DC power derived from the input AC power to the negative DC bus. In various embodiments, the second inductor, the second converter switch, and the body diode of the fifth converter switch are configured to operate as a buck converter in the first operating mode to provide DC power derived from the positive DC bus to the input AC power. In certain embodiments, the first inductor, the first switch of the first converter switch, the body diode of the second switch of the first converter switch, and the first diode are configured to operate as a boost converter in the second operating mode to provide DC power derived from the input AC power to the positive DC bus.

[0008] In one embodiment, the second inductor, the fourth converter switch, the body diode of the second converter switch, and the fifth converter switch are configured to operate as a boost converter in the second operating mode to provide DC power derived from the backup DC power to the positive DC bus. In some embodiments, the second inductor, the fourth converter switch, the body diode of the third converter switch, and the fifth converter switch are configured to operate as a buck-boost converter during the second operating mode to provide DC power derived from the backup DC power to the negative DC bus. In various embodiments, the UPS includes an output configured to provide output AC power to a load, and an inverter coupled to the output and configured to convert DC power from the positive DC bus and the negative DC bus to the output AC power and provide the output AC power to the output.

[0009] Another aspect of the present disclosure relates to a non-transitory computer readable medium having stored thereon sequences of computer executable instructions for controlling an uninterruptible power supply (UPS) including an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and provide DC power to the backup power source for charging, a positive DC bus, a negative DC bus, and a converter coupled to the input, the backup power input, and the positive and negative DC buses, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, and a third converter switch configured to couple the second inductor to the negative DC bus. The sequences of computer executable instructions include instructions instructing at least one processor to operate the first converter switch to provide DC power derived from the input AC power to the positive DC bus via the first inductor and operate at least one of the second converter switch or the third converter switch to provide DC power derived from at least one of the positive DC bus or the negative DC bus to the backup power input during a positive half cycle of the input AC voltage in a first operating mode, and operate the first converter switch to provide DC power derived from the input AC power to the negative DC bus via the first inductor and operate at least one of the second converter switch or the third converter switch to provide DC power derived from at least one of the positive DC bus or the negative DC bus to the backup power input during a negative half cycle of the input AC voltage in the first operating mode.

[0010] In one embodiment, the sequence of instructions includes instructions that cause the at least one processor to monitor input AC power received at the input, operate the UPS in a first operating mode in response to determining that the input AC power is acceptable, and operate the UPS in a second operating mode in response to determining that the input AC power is not acceptable. In some embodiments, the UPS includes an input selection circuit, and the sequence of instructions includes instructions that cause the at least one processor to control the input selection circuit to couple the converter to the input during the first operating mode, and control the input selection circuit to couple the converter to the backup power input during the second operating mode. In various embodiments, the backup power input is also configured to receive backup DC power from a backup power source, and the converter includes a fourth converter switch configured to couple the second inductor to the backup power input. In certain embodiments, the sequence of instructions includes instructions that cause the at least one processor to operate the first converter switch to provide DC power derived from the backup DC power to the positive DC bus via the first inductor in the second operating mode, and operate the fourth converter switch to provide DC power derived from the backup DC power to the negative DC bus via the second inductor in the second operating mode.

[0011] In some embodiments, the converter includes a fifth converter switch configured to couple the second inductor to the neutral connection, and the sequence of instructions includes instructions that cause the at least one processor to operate the fifth converter switch to provide DC power derived from the backup DC power to the positive DC bus via the second inductor in the second operating mode, and operate the fourth converter switch to provide DC power derived from the backup DC power to the negative DC bus via the second inductor in the second operating mode.

[0012] Another aspect of the present disclosure relates to a method of assembling an uninterruptible power supply (UPS), the method comprising: providing an input configured to receive input AC power having an input AC voltage, providing a backup power input configured to be coupled to a backup power source and provide DC power to the backup power source for charging, electrically coupling a positive DC bus and a negative DC bus to the backup power input, and coupling a converter to the input, the backup power input, and the positive and negative DC buses, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, and a third converter switch configured to couple the second inductor to the negative DC bus, wherein the UPS is voltage-frequency independent.

[0013] At least one aspect of the present disclosure also relates to an uninterruptible power supply (UPS) including an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging, a positive DC bus and a negative DC bus galvanically coupled to the backup power input, a converter coupled to the input, the backup power input, and the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, a third converter switch configured to couple the second inductor to the negative DC bus, and a fourth converter switch configured to couple the second inductor to the backup power input, and at least one controller configured to: operate the converter in a backup operating mode in response to determining that acceptable AC power is not available at the input, operate the first converter switch in the backup operating mode to provide DC power derived from the backup DC power to the positive DC bus via the first inductor, and operate the fourth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the negative DC bus via the second inductor.

[0014] At least one aspect of the present disclosure also relates to a method of operating an uninterruptible power supply (UPS). The UPS has an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging, a positive DC bus and a negative DC bus galvanically coupled to the backup power input, and a converter coupled to the input, the backup power input, and the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, a third converter switch configured to couple the second inductor to the negative DC bus, and a fourth converter switch configured to couple the second inductor to the backup power input. The method includes: controlling the UPS to operate in a backup operating mode in response to determining that acceptable AC power is not available at the input; operating the first converter switch in the backup operating mode to provide DC power derived from the backup DC power to the positive DC bus via the first inductor; and operating the fourth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the negative DC bus via the second inductor.

[0015] At least one aspect of the present disclosure also relates to at least one non-transitory computer-readable medium having stored thereon sequences of computer-executable instructions for operating an uninterruptible power supply (UPS) having an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging, a positive DC bus and a negative DC bus galvanically coupled to the backup power input, and a converter coupled to the input, the backup power input, and the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, a third converter switch configured to couple the second inductor to the negative DC bus, and a fourth converter switch configured to couple the second inductor to the backup power input. The sequences of computer-executable instructions include instructions instructing at least one processor to: control the UPS to operate in a backup operating mode in response to determining that acceptable AC power is not available at the input; operate the first converter switch in the backup operating mode to provide DC power derived from the backup DC power to the positive DC bus via the first inductor; and operate the fourth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the negative DC bus via the second inductor.

[0016] At least one aspect of the disclosure also relates to an uninterruptible power supply (UPS) including an input configured to receive input AC power having an input AC voltage, a backup power input configured to be coupled to a backup power source and receive backup DC power from the backup power source and provide DC power to the backup power source for charging, a positive DC bus and a negative DC bus galvanically coupled to the backup power input, a converter coupled to the input, the backup power input, and the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch configured to couple the first inductor to a neutral connection, a second converter switch configured to couple the second inductor to the positive DC bus, a third converter switch configured to couple the second inductor to the negative DC bus, a fourth converter switch configured to couple the second inductor to the backup power input, and a fifth converter switch configured to couple the second inductor to the neutral connection, and at least one controller configured to: operate the converter in a backup operating mode in response to determining that acceptable AC power is not available at the input; operate the fifth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the positive DC bus via the second inductor; and operate the fourth converter switch in the backup operating mode to provide DC power derived from the backup DC power to the negative DC bus via the second inductor. BRIEF DESCRIPTION OF DRAWINGS

[0017] Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The drawings are included to provide a illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented with a like numeral. For purposes of clarity, not every component can be called out in every drawing. In the drawings:

[0018] Figure 1 is a functional block diagram of a UPS according to aspects described herein;

[0019] Figure 2 is a schematic diagram of a UPS front-end topology according to aspects described herein;

[0020] Figure 3A and Figure 3B is Figure 2 a schematic diagram of a UPS front-end topology of

[0021] Figure 4A and Figure 4B yes Figure 2 A schematic diagram of the UPS front-end topology, illustrating the charger functionality during online operation modes according to the aspects described herein;

[0022] Figure 5A and Figure 5B yes Figure 2 A schematic diagram of the UPS front-end topology is provided, illustrating the standby operation modes according to the aspects described herein; and

[0023] Figure 6 yes Figure 2 A schematic diagram of the UPS front-end topology is shown, illustrating the standby operation mode during the positive DC bus cycle according to the aspects described herein. Detailed Implementation

[0024] The examples of methods and systems discussed herein are not limited in application to the details of the construction and arrangement of components set forth in the following description or shown in the accompanying drawings. These methods and systems can be implemented in other embodiments and can be practiced or performed in various ways. The examples of specific implementations provided herein are for illustrative purposes only and are not intended to be limiting. In particular, actions, components, elements, and features discussed in conjunction with any one or more examples are not intended to be excluded from similar roles in any other examples.

[0025] Furthermore, the wording and terminology used herein are for illustrative purposes and should not be construed as limiting. Any reference to examples, embodiments, components, elements, or actions of systems and methods mentioned in the singular herein may also cover embodiments comprising multiple embodiments, and any reference to any embodiment, component, element, or action mentioned herein in the plural may also cover embodiments comprising only the singular. References in either the singular or plural form are not intended to limit the currently disclosed systems or methods, their components, actions, or elements. The terms “comprising,” “including,” “having,” “containing,” “involving,” and variations thereof, as used herein, are intended to cover the items listed thereafter and their equivalents, as well as additional items. References to “or” may be interpreted inclusively, such that any term described using “or” may refer to any one, multiple, or all of the terms described. Furthermore, in the event of any inconsistency in the use of terminology between this document and documents incorporated herein by reference, the terminology used in the incorporated references shall supplement the terminology used in this document; in the case of irreconcilable inconsistencies, the term “use” as used in this document shall prevail.

[0026] As described above, power devices such as uninterruptible power supplies (UPS) can be used to provide regulated uninterrupted power to sensitive and / or critical loads. Online UPSs use a power factor correction converter (PFC) circuit to rectify the input AC power supplied by the power company to provide DC power to at least one DC bus. The rectified DC power on the DC bus can be used to charge the battery when mains power is available. In the absence of mains power, the battery discharges and provides DC power to the DC bus. Based on the DC power on the DC bus, the inverter generates the AC output voltage supplied to the load. Because power is supplied to the DC bus from the mains or battery, the UPS output power is uninterrupted if the mains fails and the battery is fully charged. Online UPSs can also operate in bypass mode, where unregulated power with basic protection is supplied directly to the load from the AC power source via a bypass path.

[0027] In many cases, the front-end topology of an online UPS includes a PFC converter to provide DC power to the DC bus when the AC trunk is available, and a separate DC / DC converter to provide DC power from the battery to the DC bus when the AC trunk is unavailable. In some cases, the front-end topology may include a separate charger (i.e., a DC / DC converter) configured to charge the battery. Therefore, these front-end UPS topologies typically have a high component count, which can lead to increased cost, increased system complexity, and reduced power density. Furthermore, such front-end UPS topologies often include components that are unused or idle during at least one operating mode of the UPS.

[0028] This document provides a more cost-effective and compact front-end topology for online UPS systems. In at least one embodiment, the front-end topology includes an integrated converter configured to operate as a PFC converter, a DC / DC converter, and a battery charger. In one example, the integrated converter is configured to supply power to both the positive and negative DC buses while simultaneously charging the battery using power from both the positive and negative DC buses. In some examples, the improved front-end topology may have a reduced component count, thereby increasing the UPS's power density and reducing costs.

[0029] Figure 1This is a block diagram of one embodiment of an online UPS 100, which can provide regulated power from input AC power received at input 102 and backup DC power from a backup power source 112 (e.g., a battery) to output 110. The UPS 100 can be configured to provide output AC power with voltage and frequency independent of the input AC power. In some examples, the backup power source 112 may be included in the UPS 100; however, in other examples, the backup power source 112 may be external to the UPS 100. The UPS 100 includes a converter 104, a DC bus 106, an inverter 108, and a controller 114 for controlling the converter 104 and the inverter 108. The DC bus 106 is coupled between the converter 104 and the inverter 108.

[0030] Input terminal 102 is configured to receive input AC power with an input voltage level from an AC power source. Controller 114 monitors the input AC power received by input terminal 102 and is configured to operate UPS 100 in different operating modes based on the state of the input AC power received by input terminal 102. When the AC power supplied to input terminal 102 is acceptable (i.e., above the input power quality threshold), controller 114 operates UPS 100 in online operating mode.

[0031] In online operation mode, AC power from input 102 is supplied to converter 104. Controller 114 operates converter 104 to convert AC power to DC power and supplies the DC power to DC bus 106. DC power from DC bus 106 is supplied to inverter 108. Alternatively, DC power from DC bus 106 can be supplied directly from converter 104 or via a separate DC / DC converter (e.g., a charger) to battery 112 for charging. Controller 114 operates inverter 108 to convert DC power to regulated AC power and supplies the regulated AC power to the load coupled to output 110.

[0032] When the AC power supplied to input 102 is unacceptable (i.e., below the input power quality threshold), controller 114 operates UPS 100 in standby mode. In standby mode, DC power from backup power supply 112 is supplied to DC bus 106. Inverter 108 receives DC power from DC bus 106, and controller 114 operates inverter 108 to convert the DC power from DC bus 106 into regulated AC power, which is then supplied to output 110.

[0033] As described above, many online UPS topologies employ separate DC / DC converters to convert input AC power and standby DC power. For example, in such a topology, converter 104 may include a PFC converter and a separate DC / DC converter, the PFC converter being configured to provide DC power derived from the input AC power to DC bus 106 during online operation mode, and the separate DC / DC converter being configured to provide DC power derived from the standby DC power to DC bus 106 during standby operation mode. In some examples, the DC / DC converter may be configured to charge battery 112 from the DC bus; however, in other examples, converter 104 (or UPS 100) may include a separate charger (i.e., the DC / DC converter) to charge battery 112.

[0034] While this topology can be used to provide uninterrupted power, using multiple converters requires additional components. For example, the charger may include additional components such as switches, diodes, inductors, and transformers (e.g., buck transformers) to provide the battery with DC power derived from the input AC power or the DC bus for charging. Therefore, these multiple-converter topologies can increase cost and complexity while reducing the power density of the UPS.

[0035] Additionally, in certain environments (e.g., developing economies), frequent and prolonged power outages may drive the need for large (or high-power) battery packs. In such cases, the charger included in converter 104 (or UPS 100) can be configured as a high-power charger. In other examples, the charger can be configured as a high-power charger to support specific types of batteries (e.g., lithium) and / or provide specific features (e.g., fast charging). In some examples, configuring the charger as a high-power converter can further increase the size and cost of UPS 100.

[0036] Therefore, it may be advantageous to configure the front-end topology of UPS 100 (e.g., converter 104) to provide DC power derived from input AC power or standby DC power to DC bus 106 and to use the DC power derived from DC bus 106 to charge battery 112 as an integrated converter.

[0037] Figure 2 This is a schematic diagram of the front-end topology 200 according to the aspects described herein. In one example, the front-end topology 200 is configured to be included in an online UPS (i.e., a voltage-frequency independent UPS). For example, the front-end topology 200 includes components corresponding to... Figure 1The UPS 100 includes converter 104 and DC bus 106, converter 204 and DC bus 206. In some examples, DC bus 206 includes a positive DC bus 206a and a negative DC bus 206b.

[0038] As shown in the figure, the front-end topology 200 includes an input terminal 202 coupled to an input AC source 203 and a backup power input terminal 214 coupled to a backup power source 212 (e.g., a battery). In some examples, the backup power source 212 may be included in a UPS; however, in other examples, the backup power source 212 may be separate from the UPS. In some examples, the front-end topology 200 is configured with a pass-through neutral connection to the input terminal 202 and the backup power source 212 to minimize EMI / EMC issues.

[0039] In one example, converter 204 includes a first converter switch 216, a second converter switch 218, a third converter switch 220, a fourth converter switch 222, and a fifth converter switch 224, an input selection circuit 226, a first inductor 228, a second inductor 230, a first diode 232, and a second diode 234. In one embodiment, converter switches 216-224 are metal-oxide-semiconductor field-effect transistors (MOSFETs); however, in other embodiments, different types of switches or transistors (e.g., insulated-gate bipolar transistors (IGBTs)) may be used. In some examples, each switch has a gate, a drain, and a source. In this context, "drain" can refer to any device terminal into which current enters the switch. Similarly, "source" can refer to any device terminal into which current leaves the switch.

[0040] In some instances, the first converter switch 216 is a bidirectional switching circuit that includes a first switch 216a coupled in series with a second switch 216b. Thus, by turning on (i.e., closing) the first switch 216a and turning off (i.e., opening) the second switch 216b to provide a conductive path through the body diodes of the first and second switches 216a, the first converter switch 216 can operate in a first state. Similarly, by turning on (i.e., closing) the second switch 216b and turning off (i.e., opening) the first switch 216a to provide a conductive path through the body diodes of the second and first switches 216b, the first converter switch 216 can operate in a second state.

[0041] As shown in the figure, the input selection circuit 226 is configured to couple a first inductor 228 to either input 202 or standby power input 214. In one example, a first terminal of the first inductor 228 is coupled to a first converter switch 216, the anode of a first diode 232, and the cathode of a second diode 234, and a second terminal of the first inductor 228 is coupled to the input selection circuit 226. The cathode of the first diode 232 is coupled to the positive DC bus 206a, and the anode of the second diode 234 is coupled to the negative DC bus 206b. In some examples, a first terminal of the second inductor 230 is coupled to a first converter switch 218 and a fifth converter switch 224, and a second terminal of the second inductor 230 is coupled to a third converter switch 220 and a fourth converter switch 222. The second converter switch 218 is coupled between the first terminal of the second inductor 230 and the positive DC bus 206a, and the fifth converter switch 224 is coupled between the first terminal of the second inductor 230 and the neutral line. The third converter switch 220 is coupled between the second terminal of the second inductor 230 and the negative DC bus 206b, and the fourth converter switch 222 is coupled between the second terminal of the second inductor 230 and the backup power input terminal 214.

[0042] In one example, positive DC bus capacitor 236a is coupled between positive DC bus 206a and the neutral line, and negative DC bus capacitor 236b is coupled between negative DC bus 206b and the neutral line. In some examples, DC bus capacitors 236a and 236b are polarized capacitors. For example, positive DC bus capacitor 236a may have a positive side coupled to positive DC bus 206a and a negative side coupled to the neutral line. Similarly, negative DC bus capacitor 236b may have a positive side coupled to the neutral line and a negative side coupled to negative DC bus 206b. Figure 2 As shown, DC buses 206a and 206b are current-grounded to the standby power input terminal 214.

[0043] In at least one example, converter 204 of front-end topology 200 can operate in various operating modes. For example, in the online operation mode of the UPS, control input selection circuit 226 couples the second terminal of first inductor 228 to input 202, so that AC power from input 202 is supplied to converter 204. Converter 204 converts the AC power to DC power and supplies the DC power to DC buses 206a, 206b. Additionally, during online operation mode, converter 204 can be operated to supply DC power derived from DC buses 206a, 206b to backup power input 214 to charge backup power supply 212.

[0044] In some examples, converter 204 is configured to operate as a bidirectional converter. Therefore, converter 204 can be considered "bidirectional" because it can supply power to and from backup power input 214 (i.e., backup power supply 212). Conversely, some unidirectional chargers can be configured to supply power to an energy storage device or input, but may not draw power from it.

[0045] Figure 3A and Figure 3B This is a schematic diagram illustrating the PFC function of converter 204 during the positive and negative half-cycles of the input AC voltage corresponding to the input AC power in the online operation mode of the UPS.

[0046] like Figure 3A As shown, in online operation mode and during the positive half-cycle of the input AC voltage, the first converter switch 216 is operated to provide DC power derived from the input AC power (provided by the input AC source 203) to the positive DC bus 206a. In some examples, the first converter switch 216, the first inductor 228, and the first diode 232 operate as a PFC boost converter to provide DC power to the positive DC bus 206a.

[0047] In one example of the online operation mode during the positive half-cycle of the input AC voltage, the first switch 216a of the first converter switch 216 is turned on and off to provide PFC boost converter operation. For example, when the first switch 216a is on (i.e., closed), the first terminal of the first inductor 228 is coupled to the neutral line. Therefore, a conductive path 302 for input AC power is provided through the first converter switch 216, thereby energizing the inductor 228. In one example, the conductive path 302 includes the body diode of the second switch 216b of the first converter switch 216. Similarly, when the first switch 216a is off (i.e., open), the first inductor 228 is decoupled from the neutral line. Thus, a conductive path 304 for input AC power is provided through the first inductor 228 and the first diode 232 to supply DC power to the positive DC bus 206a and charge the positive DC bus capacitor 236a.

[0048] like Figure 3B As shown, in online operation mode and during the negative half-cycle of the input AC voltage, the first converter switch 216 is operated to provide DC power derived from the input AC power (provided by the input AC source 203) to the negative DC bus 206b. In some examples, the first converter switch 216, the first inductor 228, and the second diode 234 operate as a PFC boost converter to provide DC power to the negative DC bus 206b.

[0049] In one example of the online operation mode during the negative half-cycle of the input AC voltage, the second switch 216b of the first converter switch 216 is turned on and off to provide PFC boost converter operation. For example, when the second switch 216b is on (i.e., closed), the first terminal of the first inductor 228 is coupled to the neutral line. This provides a conductive path 402 for input AC power through the first converter switch 216, thereby energizing the first inductor 228. In one example, the conductive path 402 includes the body diode of the first switch 216a of the first converter switch 216. Similarly, when the second switch 216b is off (i.e., open), the first inductor 228 is decoupled from the neutral line. This provides a conductive path 404 for input AC power through the first inductor 228 and the second diode 234 to supply DC power to the negative DC bus 206b and charge the negative DC bus capacitor 236b.

[0050] As described above, during the online operation mode of the UPS, converter 204 can provide DC power derived from DC buses 206a and 206b to the backup power input 214 to charge the backup power supply 212. In one example, during the online operation mode, converter 204 can use DC power derived from the positive DC bus 206A and / or the negative DC bus 206B to charge the backup power supply 212 during the positive and negative half-cycles of the input AC voltage.

[0051] Figure 4A and Figure 4B This is a schematic diagram illustrating the charger function of converter 204 during the online operation mode of the UPS.

[0052] like Figure 4A As shown, during online operation mode, the third converter switch 220 can be operated to supply the DC power derived from the negative DC bus 206B (i.e., the negative DC bus capacitor 236B) to the backup power input 214 to charge the backup power supply 212. In some examples, the body diodes of the third converter switch 220, the second inductor 230, and the fourth converter switch 222 operate as buck-boost converters to provide the DC power derived from the negative DC bus 206B to the backup power input 214.

[0053] In one example, the third converter switch 220 is turned on and off to provide buck-boost converter operation. For example, when the third converter switch 220 is on (i.e., closed), the second terminal of the second inductor 230 is coupled to the negative DC bus 206b. Thus, a conductive path 306 is provided through the third converter switch 220 for the DC power stored by the negative DC bus capacitor 236b, thereby energizing the second inductor 230. In one example, the conductive path 306 includes the body diode of the fifth converter switch 224; however, in some examples, the fifth converter switch 224 may be turned on (i.e., closed) to minimize losses. Similarly, when the third converter switch 220 is off (i.e., open), the second inductor 230 is decoupled from the negative DC bus 236b. Thus, a conductive path 308 is provided through the body diode of the fourth converter switch 222 and the body diode of the fifth converter switch 224 (or the fifth converter switch 224), thereby allowing the second inductor 230 to stop energizing and provide DC power to the backup power input 214 to charge the backup power supply 212. In some examples, the DC power provided to the backup power input 214 may have a voltage level different from (e.g., lower) the voltage level of the negative DC bus 206B.

[0054] In one example, in the online operation mode of the UPS, converter 204 can be operated to provide DC power derived from the negative DC bus 206b to the backup power input 214 during the positive and negative half-cycles of the input AC voltage. For example, when converter 204 supplies power to the positive DC bus 206A (e.g., Figure 3A ) and negative DC bus 206B (e.g., Figure 3B When providing power, the third converter switch 220 can be operated as described above.

[0055] Similarly, such as Figure 4B As shown, during online operation mode, the second converter switch 218 can be operated to supply DC power derived from the positive DC bus 206A (i.e., the positive DC bus capacitor 236A) to the backup power input 214 to charge the backup power supply 212. In some examples, the body diodes of the second converter switch 218, the second inductor 230, and the fifth converter switch 224 operate as a buck converter to supply DC power derived from the positive DC bus 206A to the backup power input 214.

[0056] In one example, the second converter switch 218 is turned on and off to provide buck converter operation. For example, when the second converter switch 218 is on (i.e., closed), a first terminal of the second inductor 230 is coupled to the positive DC bus 206a. Thus, a conductive path 406 is provided through the second converter switch 218 for the DC power stored by the positive DC bus capacitor 236a, thereby energizing the second inductor 230. In one example, the conductive path 406 includes the body diode of the fourth converter switch 222; however, in some examples, the fourth converter switch 222 may be turned on (i.e., closed) to minimize losses. Similarly, when the second converter switch 218 is off (i.e., open), the second inductor 230 is decoupled from the positive DC bus 236a. Thus, a conductive path 408 is provided through the body diode of the fourth converter switch 222 (or the body diode of the fourth converter switch 222) and the body diode of the fifth converter switch 224, thereby allowing the second inductor 230 to stop energizing and provide DC power to the backup power input 214 to charge the backup power supply 212. In some examples, the DC power provided to the backup power input 214 may have a voltage level different from (e.g., lower) the voltage level of the positive DC bus 206a.

[0057] In one example, in the online operation mode of the UPS, converter 204 can be operated to provide DC power derived from the positive DC bus 206a to the backup power input 214 during the positive and negative half-cycles of the input AC voltage. For example, when converter 204 supplies power to the positive DC bus 206a (e.g., Figure 3A ) and negative DC bus 206b (e.g., Figure 3B When providing power, the second converter switch 218 can be operated as described above.

[0058] In one example, the charging capacity of converter 204 corresponds to the power demand at output 110 of UPS 100 (i.e., the output of inverter 108). For example, when the UPS is not experiencing full load at output 110, converter 204 can operate with a charging capacity of up to 50% of the inverter 110's capacity. Thus, the charging capacity of converter 204 can be scaled or adjusted based on the power demand at output 110 of UPS 100 (i.e., the load on inverter 108). In some examples, the second inductor 230 can be resized (e.g., increased) to provide different charging capacities (up to the full capacity of inverter 110).

[0059] In standby operation mode, the control input selection circuit 226 couples the second terminal of inductor 228 to the standby power input terminal 214, so that the standby DC power from the standby power supply 212 is provided to the converter 204. The converter 204 converts the standby DC power into DC power and provides the DC power to DC buses 206a and 206b.

[0060] Figure 5A and Figure 5B This is a schematic diagram illustrating the operation of converter 204 during the standby operation mode of the UPS.

[0061] like Figure 5A As shown, during standby operation mode and positive DC bus cycle, the first converter switch 216 is operated to provide DC power derived from the standby DC power (provided by the standby power supply 212) to the positive DC bus 206a. In some examples, the first converter switch 216, the first inductor 228, and the first diode 232 operate as a boost converter to provide DC power to the positive DC bus 206a.

[0062] In one example of the standby operation mode during the positive DC bus cycle, the first switch 216a of the first converter switch 216 is turned on and off to provide boost converter operation. For example, when the first switch 216a is on (i.e., closed), the first terminal of the first inductor 228 is coupled to the neutral line. Thus, a conductive path 502 for standby DC power is provided through the first converter switch 216, thereby energizing the first inductor 228. In one example, the conductive path 502 includes the body diode of the second switch 216b of the first converter switch 216. Similarly, when the first switch 216a is off (i.e., open), the first inductor 228 is decoupled from the neutral line. Thus, a conductive path 504 for standby DC power is provided through the first inductor 228 and the first diode 232 to supply DC power to the positive DC bus 206a and charge the positive DC bus capacitor 236a.

[0063] like Figure 5B As shown, during standby operation mode and negative DC bus cycle, the fourth converter switch 222 operates to supply DC power derived from the standby DC power to the negative DC bus 206b. In some examples, the body diodes of the fourth converter switch 222, the second inductor 230, and the third converter switch 220 operate as buck-boost converters to supply DC power to the negative DC bus 206b.

[0064] In one example of the standby operation mode during the negative DC bus cycle, the fourth converter switch 222 is turned on and off to provide buck-boost converter operation. For example, when the fourth converter switch 222 is on (i.e., closed), the second terminal of the second inductor 230 is coupled to the standby power input 214. Thus, a conductive path 506 for standby DC power is provided through the fourth converter switch 222, thereby energizing the second inductor 230. In one example, the conductive path 506 includes a fifth converter switch 224, which is on (i.e., closed) during the negative DC bus cycle. Similarly, when the fourth converter switch 222 is off (i.e., open), the second inductor 230 is decoupled from the standby power input 214. Thus, a conductive path 508 is provided through the body diode of the third converter switch 220, allowing the second inductor 230 to stop energizing and supply DC power to the negative DC bus 206b and charge the negative DC bus capacitor 236b.

[0065] In one example, the positive DC bus cycle during standby operation mode corresponds to the positive half-cycle of the output AC voltage. Similarly, the negative DC bus cycle during standby operation mode corresponds to the negative half-cycle of the output AC voltage. In some examples, the output AC voltage is controlled by an inverter coupled to DC buses 206a and 206b (e.g., Figure 1 The inverter 108 is provided.

[0066] In some examples, alternative control schemes can be used to supply DC power to DC buses 206a and 206b during standby operation. For example, Figure 6 This is a schematic diagram illustrating the alternative operation of converter 204 for the positive DC bus cycle during the standby operation mode of the UPS.

[0067] like Figure 6 As shown, during standby operation mode and positive DC bus cycle, the fifth converter switch 224 can be operated to provide DC power derived from the standby DC power (provided by the standby power supply 212) to the positive DC bus 206a. In some examples, the body diodes of the fifth converter switch 224, the second inductor 230, and the second converter switch 218 operate as boost converters to provide DC power to the positive DC bus 206a.

[0068] In one example of the standby operating mode during the positive DC bus cycle, the fifth converter switch 224 is turned on and off to provide boost converter operation. For example, when the fifth converter switch 224 is on (i.e., closed), a first terminal of the second inductor 230 is coupled to the neutral line. Thus, a conductive path 602 for standby DC power is provided through the fifth converter switch 224, thereby energizing the second inductor 230. In one example, the conductive path 602 includes a fourth converter switch 222, which is turned on (i.e., closed) during the positive DC bus cycle. Similarly, when the fifth converter switch 224 is off (i.e., open), the second inductor 230 is decoupled from the neutral line. Thus, a conductive path 604 is provided through the body diode of the second converter switch 218, allowing the second inductor 230 to stop energizing and supply DC power to the positive DC bus 206a and charge the positive DC bus capacitor 236a.

[0069] In one example, converter 204 can be configured to utilize the positive DC bus cycle during standby operation mode. Figure 6 The control scheme, and utilizes during the negative DC bus cycle in standby operation mode. Figure 5B The control scheme. In some examples, in order to support Figure 6 In this control scheme, the second inductor 230 is resized (e.g., increased) to match the full capacity of the inverter 108. Due to this resizing of the second inductor 230, the converter 204 can operate at up to the full charging capacity of the inverter 108 during online operation.

[0070] As described above, this document provides a more cost-effective and compact front-end topology for online UPS. In at least one embodiment, the front-end topology includes an integrated converter configured to operate as a PFC converter, a DC / DC converter, and a battery charger. In one example, the integrated converter is configured to supply power to both the positive and negative DC buses while simultaneously charging the battery using the power from both the positive and negative DC buses. In some examples, by utilizing different components of the integrated converter to charge the battery from the DC bus while simultaneously supplying power to the DC bus, separate chargers and associated components can be eliminated from the front-end topology (and UPS). Thus, the improved front-end topology can have a reduced number of components, thereby increasing the power density of the UPS and reducing costs.

[0071] In at least one embodiment, an uninterruptible power supply (UPS) is described herein, comprising an input, an energy storage device interface, an output, a power factor correction (PFC) circuit, a capacitor, a bidirectional converter, and a switch. The input is configured to receive input power from an input power source and has a trunk neutral connection coupled to a reference node. The energy storage device interface is configured to be coupled to an energy storage device to provide backup power and has an energy storage device neutral connection coupled to the reference node. The output is configured to provide output power derived from at least one of the input power and the backup power. The power factor correction (PFC) circuit includes a PFC input. The capacitor is coupled to the PFC and currently coupled to the energy storage device interface. The bidirectional converter is coupled to the input and the energy storage device interface. The switch is coupled to the energy storage device interface and the PFC input.

[0072] Having described several aspects of at least one embodiment of the invention, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art. These changes, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the invention. Therefore, the foregoing description and drawings are merely exemplary.

Claims

1. An uninterruptible power supply (UPS), the UPS comprising: The input terminal is configured to receive input AC power with an input AC voltage. The backup power input is configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging. A positive DC bus and a negative DC bus, wherein the positive DC bus and the negative DC bus are electrically coupled to the backup power input terminal; A converter coupled to the input terminal, the backup power input terminal, the positive DC bus, and the negative DC bus, the converter comprising: First inductor, Second inductor, A first converter switch is configured to couple the first inductor to a neutral connection. A second converter switch is configured to couple the second inductor to the positive DC bus. A third converter switch is configured to couple the second inductor to the negative DC bus, and A fourth converter switch is configured to couple the second inductor to the backup power input; and At least one controller is configured as follows: In response to the determination that acceptable AC power is unavailable at the input, the converter operates in standby operating mode. In the standby operation mode, the first converter switch is operated to provide DC power derived from the standby DC power to the positive DC bus via the first inductor, and In the standby operating mode, the fourth converter switch is operated to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

2. The UPS according to claim 1, wherein, The at least one controller is further configured to: In response to determining that acceptable AC power is available at the input, the converter is operated in normal operating mode.

3. The UPS according to claim 1, wherein, The at least one controller is also configured to operate the fourth converter switch in standby mode to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

4. The UPS according to claim 3, wherein, Operating the fourth converter switch to provide DC power derived from the standby DC power to the negative DC bus via the second inductor includes operating the fourth converter switch as a component of a buck-boost converter.

5. The UPS according to claim 3, wherein, Operating the fourth converter switch to provide DC power derived from the backup DC power to the negative DC bus via the second inductor includes controlling the fourth converter switch to couple the second inductor to the backup power input and to conduct power from the backup power input to the second inductor via the fourth converter switch.

6. The UPS according to claim 5, wherein, Conducting power to the second inductor will energize the second inductor, and wherein operating the fourth converter switch to provide the negative DC bus with DC power derived from the backup DC power also includes controlling the fourth converter switch to decouple the second inductor from the backup power input.

7. The UPS according to claim 6, wherein, Controlling the fourth converter switch to decouple the second inductor from the backup power input will de-energize the second inductor, and wherein de-energizing the second inductor includes the second inductor releasing the stored energy to the negative DC bus.

8. The UPS according to claim 2, further comprising at least one controller, wherein, The converter further includes a fifth converter switch configured to couple the second inductor to the neutral connection, and the at least one controller is configured to: In standby operation mode, the fifth converter switch is operated to provide DC power derived from the standby DC power to the positive DC bus via the second inductor; as well as In the standby operating mode, the fourth converter switch is operated to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

9. The UPS of claim 1, further comprising at least one controller configured to operate the fourth converter switch as a component of the buck-boost converter.

10. The UPS of claim 1, further comprising at least one controller configured to control the fourth converter switch to couple the second inductor to the backup power input, thereby conducting power from the backup power input to the second inductor via the fourth converter switch.

11. The UPS according to claim 10, wherein, Conducting power to the second inductor will energize the second inductor, and wherein the at least one controller is also configured to control the fourth converter switch to decouple the second inductor from the backup power input.

12. The UPS according to claim 11, wherein, Controlling the fourth converter switch to decouple the second inductor from the backup power input will de-energize the second inductor, and de-energizing the second inductor includes the second inductor releasing the stored energy to the negative DC bus.

13. A method of operating an uninterruptible power supply (UPS), the UPS having an input terminal, a backup power input terminal, a positive DC bus and a negative DC bus, and a converter, the input terminal being configured to receive input AC power having an input AC voltage, the backup power input terminal being configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging, the positive DC bus and the negative DC bus being current-grounded to the backup power input terminal; the converter being coupled to the input terminal, the backup power input terminal, the positive DC bus and the negative DC bus, the converter including a first inductor, a second inductor, a first converter switch, a second converter switch, a third converter switch and a fourth converter switch, the first converter switch being configured to couple the first inductor to a neutral connection, the second converter switch being configured to couple the second inductor to the positive DC bus, the third converter switch being configured to couple the second inductor to the negative DC bus, and the fourth converter switch being configured to couple the second inductor to the backup power input terminal, the method comprising: In response to determining that acceptable AC power is unavailable at the input, the UPS is controlled to operate in standby mode. In the standby operation mode, the first converter switch is operated to provide DC power derived from the standby DC power to the positive DC bus via the first inductor; as well as In the standby operating mode, the fourth converter switch is operated to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

14. At least one non-transitory computer-readable medium storing a sequence of computer-executable instructions for operating an uninterruptible power supply (UPS), the UPS having an input terminal, a backup power input terminal, a positive DC bus and a negative DC bus, and a converter, the input terminal being configured to receive input AC power having an input AC voltage, the backup power input terminal being configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging, the positive DC bus and the negative DC bus being currently coupled to the backup power input terminal; the converter being coupled to the input terminal, the backup power input terminal, and the... The converter includes a positive DC bus and a negative DC bus, comprising a first inductor, a second inductor, a first converter switch, a second converter switch, a third converter switch, and a fourth converter switch. The first converter switch is configured to couple the first inductor to a neutral connection. The second converter switch is configured to couple the second inductor to the positive DC bus. The third converter switch is configured to couple the second inductor to the negative DC bus. The fourth converter switch is configured to couple the second inductor to the backup power input. The sequence of computer-executable instructions includes instructions instructing at least one processor to perform the following operations: In response to determining that acceptable AC power is unavailable at the input, the UPS is controlled to operate in standby mode. In the standby operating mode, the first converter switch is operated to provide DC power derived from the standby DC power to the positive DC bus via the first inductor; and In the standby operating mode, the fourth converter switch is operated to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

15. An uninterruptible power supply (UPS), the UPS comprising: The input terminal is configured to receive input AC power with an input AC voltage. The backup power input is configured to be coupled to a backup power source and to receive backup DC power from the backup power source and to provide DC power to the backup power source for charging. A positive DC bus and a negative DC bus, wherein the positive DC bus and the negative DC bus are electrically coupled to the backup power input terminal; A converter coupled to the input terminal, the backup power input terminal, the positive DC bus, and the negative DC bus, the converter comprising: First inductor, Second inductor, A first converter switch is configured to couple the first inductor to a neutral connection. A second converter switch is configured to couple the second inductor to the positive DC bus. A third converter switch is configured to couple the second inductor to the negative DC bus, and A fourth converter switch is configured to couple the second inductor to the backup power input; and A fifth converter switch is configured to couple the second inductor to the neutral connection; and At least one controller is configured as follows: In response to the determination that acceptable AC power is unavailable at the input, the converter operates in standby operating mode. In the standby operation mode, the fifth converter switch is operated to provide DC power derived from the standby DC power to the positive DC bus via the second inductor, and In the standby operating mode, the fourth converter switch is operated to provide DC power derived from the standby DC power to the negative DC bus via the second inductor.

16. The UPS according to claim 15, wherein, Operating the fourth converter switch to provide DC power derived from the standby DC power to the negative DC bus via the second inductor includes operating the fourth converter switch as a component of a buck-boost converter.

17. The UPS according to claim 15, wherein, Operating the fourth converter switch to provide DC power derived from the backup DC power to the negative DC bus via the second inductor includes controlling the fourth converter switch to couple the second inductor to the backup power input and conduct power from the backup power input to the second inductor via the fourth converter switch.

18. The UPS according to claim 17, wherein, Conducting power to the second inductor will energize the second inductor, and wherein operating the fourth converter switch to provide the negative DC bus with DC power derived from the backup DC power also includes controlling the fourth converter switch to decouple the second inductor from the backup power input.

19. The UPS according to claim 18, wherein, Controlling the fourth converter switch to decouple the second inductor from the backup power input will de-energize the second inductor, and de-energizing the second inductor includes the second inductor releasing the stored energy to the negative DC bus.

20. The UPS of claim 15, further comprising at least one controller configured to operate the fourth converter switch as a component of the buck-boost converter.

21. The UPS according to claim 15, wherein, Conducting power to the second inductor will energize the second inductor, and wherein the at least one controller is further configured to control the fourth converter switch to decouple the second inductor from the backup power input.

22. The UPS according to claim 21, wherein, Controlling the fourth converter switch to decouple the second inductor from the backup power input will de-energize the second inductor, and wherein de-energizing the second inductor includes the second inductor releasing the stored energy to the negative DC bus.

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