Parallel modular UPS system

Abstract

Examples of the disclosure include an uninterruptible power supply (UPS) comprising at least one main input, an energy- storage-device input, an output, a bi-directional AC / DC converter, a DC / AC converter, and at least one controller configured to determine one or more power parameters indicative of at least one power source powering at least one load, and output a signal that causes the bi-directional AC / DC converter to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

Description

[0001] PARALLEL MODULAR UPS SYSTEM

[0002] CROSS REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to Chinese Patent Application No. 202410880528.6, titled “PARALLEL MODULAR UPS SYSTEM,” filed July 2, 2024, the entire contents of which are incorporated herein by reference in their entirety for all purposes.

[0004] BACKGROUND

[0005] 1. Field of the Disclosure

[0006] At least one example in accordance with the present disclosure relates generally to power devices.

[0007] 2. Discussion of Related Art

[0008] Power devices, such as uninterruptible power supplies (UPSs), may be used to provide regulated, uninterrupted power for sensitive and / or critical loads, such as computer systems and other data-processing systems. Examples of UPSs include online UPSs, offline UPSs, line- interactive UPSs, as well as others. UPSs may provide output power to a load. The output power may be derived from a primary source of power, such as a utility-mains source, and / or derived from a back-up source of power, such as an energy-storage device.

[0009] SUMMARY

[0010] Examples of the methods and systems discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The methods and systems may be capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes and are not intended to be limiting. Acts, components, elements, and features discussed in connection with any one or more examples may be configured to operate and / or be implemented in a similar role in any other examples. The phraseology and terminology used herein is for the purpose of description.

[0011] References to examples, embodiments, components, elements, or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality. Similarly, references in plural to embodiments, components, elements, or acts may be implemented as a singularity. References in the singular or plural form may therefore not be intended to limit the presently disclosed systems or methods, their components, acts, or elements. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations so forth, may encompass the items listed thereafter and equivalents thereof as well as additional items.

[0012] References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. For example, the phrase “at least one of A or B” may refer A and / or B — that is, A only, B only, or A and B together. In addition, in the event of inconsistent usages of terms between this document and documents incorporated herein by reference, the term usage in the incorporated documents is supplementary to this document. For irreconcilable differences, the term usage in this document controls.

[0013] According to at least one aspect of the present disclosure, an uninterruptible power supply (UPS) is provided comprising at least one main input, an energy- storage-device input, an output, a bi-directional AC / DC converter, a DC / AC converter, and at least one controller configured to determine one or more power parameters indicative of at least one power source powering at least one load, and output a signal that causes the bi-directional AC / DC converter to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

[0014] In at least one example, the output is configured to be coupled to a UPS load, and wherein the at least one load includes the UPS load. In at least one example, the at least one power source includes a mains source, and the at least one main input is configured to receive power from the mains source, and the at least one load includes an upstream load coupled between the at least one main input and the mains source. In at least one example, the energystorage-device input is configured to be coupled to at least one energy- storage device, and the at least one controller is further configured to cause the bi-directional AC / DC converter to generate the compensation current using energy derived from the at least one energy- storage device. In at least one example, the UPS includes at least one bypass switch coupled to the at least one main input at a first connection and to the output at a second connection, the at least one bypass switch being coupled in parallel with the bi-directional AC / DC converter and the DC / AC converter. In at least one example, the at least one controller is further configured to control the at least one bypass switch to selectively conduct power from the at least one main input to the output, bypassing the bi-directional AC / DC converter and the DC / AC converter. In at least one example, the at least one controller is further configured to output a second signal that causes the DC / AC converter to generate a second compensation current based on the one or more power parameters, wherein the second compensation current increases the linearity of power delivered to one or more loads.

[0015] In at least one example, the at least one main input includes a first input, and the UPS further includes a first switch coupled to the first input and a second switch coupled between the bi-directional AC / DC converter and the output. In at least one example, the bi-directional AC / DC converter is configured to provide a first portion of the compensation current to a first load via the first switch, and is configured to provide a second portion of the compensation current to a second load via the second switch. In at least one example, the at least one main input further includes a second input, the UPS further comprising a third switch coupled to the second input. In at least one example, the UPS includes a bypass switch coupled between the second switch and the output. In at least one example, the at least one main input includes a first input configured to be coupled to a first power source, and a second input configured to be coupled to a second power source.

[0016] Examples of the disclosure include at least one non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power supply including a bi-directional AC / DC converter, the sequences of computer-executable instructions including instructions that instruct at least one processor to determine one or more power parameters indicative of at least one power source powering at least one load, and output a signal that causes the bi-directional AC / DC converter to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

[0017] In at least one example, the power supply is further configured to be coupled to at least one energy- storage device, and the instructions further instruct at least one processor to cause the bi-directional AC / DC converter to generate the compensation current using energy derived from the at least one energy-storage device. In at least one example, the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, and the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a portion of the compensation current to the upstream load.

[0018] In at least one example, the power supply further includes an output configured to be coupled to a UPS load, and the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a first portion of the compensation current to the UPS load. In at least one example, the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, and the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a second portion of the compensation current to the upstream load.

[0019] Examples of the disclosure include a method of operating a power supply including a bidirectional AC / DC converter, the method comprising determining one or more power parameters indicative of at least one power source powering at least one load, and generating, by the bidirectional AC / DC converter, a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

[0020] In at least one example, the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, and the method includes providing, by the bi-directional AC / DC converter, at least a portion of the compensation current to the upstream load. In at least one example, the power supply further includes an output configured to be coupled to a UPS load, and the method includes providing, by the bi-directional AC / DC converter, at least a first portion of the compensation current to the UPS load.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which may not be drawn to scale. The figures are included to provide an 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 any particular embodiment. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and embodiments. In the figures, each identical or substantially similar component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures:

[0023] FIG. 1 illustrates a block diagram of a power system according to an example;

[0024] FIG. 2 illustrates another aspect of the power system according to an example;

[0025] FIG. 3 illustrates a process of operating a UPS according to an example;

[0026] FIG. 4 illustrates a process of operating the UPS in a bypass mode according to an example;

[0027] FIG. 5 illustrates a block diagram of the power system of FIG. 2 providing power compensation according to an example;

[0028] FIG. 6 illustrates a block diagram of the power system of FIG. 2 providing power compensation according to another example;

[0029] FIG. 7 illustrates a block diagram of the power system of FIG. 2 providing power compensation according to another example;

[0030] FIG. 8 illustrates a block diagram of a power system according to another example;

[0031] FIG. 9 illustrates a graph of current traces according to an example; and

[0032] FIG. 10 illustrates a block diagram of a power system according to another example.

[0033] DETAILED DESCRIPTION

[0034] As discussed above, power devices such as uninterruptible power supplies (UPSs) may be used to provide regulated, uninterruptible power to one or more loads. For example, FIG. 1 illustrates a block diagram of a power system 100 according to an example. The power system 100 includes an uninterruptible power supply (UPS) 102, one or more UPS-connected loads 104 (“UPS loads 104”), one or more non-UPS-connected loads 106 (“non-UPS loads 106”), a first power source 108, a second power source 110, and, optionally in some examples, at least one power-correction device 112 (“power-correction device 112”).

[0035] The power sources 108, 110 are coupled to, and provide power to, the UPS 102, the nonUPS loads 106, and the power-correction device 112 via a power grid 114 (“grid 114”). The UPS 102 provides power derived from the power sources to the UPS loads 104. Although the grid 114 may be illustrated with a single line in FIG. 1, the grid 114 may include multiple conductors. For example, the grid 114 may distribute three-phase power, and in some examples the first power source 108 may be coupled to the components of the power system 100 (for example, the UPS 102) via separate conductors than those connecting the second power source 110 to the components of the power system 100. In some examples, the power sources 108, 110 may include utility power supplies.

[0036] The UPS loads 104 may receive power from the power sources 108, 110 via the UPS 102. In some examples, the UPS 102 may draw power from the power sources 108, 110, condition the power using power-conditioning circuitry, and provide conditioned power to the UPS loads 104. In other examples, the UPS 102 may draw power from the power sources 108, 110 and bypass power-conditioning circuitry in the UPS 102 such that power is provided directly to the UPS loads 104. Furthermore, if power becomes unavailable from the power sources 108, 110, then the UPS 102 may draw power from an energy- storage device (such as a battery) to continue powering the UPS loads 104. Conversely, the non-UPS loads 106 may include less- critical loads and may draw power directly from the grid 114.

[0037] In some examples, the non-UPS loads 106 may include non-linear loads such as HVAC units, elevators, lighting, and so forth, which may generate harmonics and reactive current on the grid 114 and degrade the power quality on the grid 114. The UPS loads 104 may also include non-linear loads, which may be different devices but which may still degrade the power quality on the grid 114. Symptoms of low power quality may include overheating devices such as transformers, motors, drives, cables, and so forth, thermal tripping of protective devices, logic faults of digital devices, and so forth.

[0038] In some examples, the power system 100 may include an optional power-correction device 112. The power-correction device 112 may include one or more devices configured to improve or correct power quality on the grid 114 (for example, to address issues introduced by the non-UPS loads 106). For example, the power-correction device 112 may be configured to inject or absorb real or reactive power to the grid 114, and / or may inject or absorb harmonics to improve power quality on the grid 114. In some examples, the power-correction device 112 may include components such as active power filters, static VAR generators, additional or different components, a combination thereof, and so forth.

[0039] In various examples, the UPS 102 may be configured to compensate for harmonics and / or reactive power which would otherwise be introduced by the UPS loads 104. Moreover, in at least one example discussed herein, the UPS 102 may be configured to compensate for harmonics and / or reactive power generated by the non-UPS loads 106. In various examples, the powercorrection device 112 may be omitted where the UPS 102 is configured to compensate for power generated by the non-UPS loads 106. In other examples, the power-correction device 112 may be included even if the UPS 102 is configured to compensate for power generated by the non-UPS loads 106.

[0040] FIG. 2 illustrates another aspect of the power system 100 according to an example. The power system 100 includes a UPS 201, which may be one example of the UPS 102. The grid 114 includes a first grid connection 114a (which may include multiple conductors in a multi-phase system) coupled between the first power source 108 and the UPS 201, and a second grid connection 114b (which may similarly include multiple conductors) coupled between the second power source 110 and the UPS 201. The non-UPS loads 106 include a first group of one or more non-UPS loads 106a (“first non-UPS loads 106a”) coupled to the first power source 108 via the first grid connection 114a, and a second group of one or more non-UPS loads 106b (“second non-UPS loads 106b”) coupled to the second power source 110 via the second grid connection 114b. The power system 100 includes one or more first power-parameter sensors 200 (“first sensor 200”) and one or more second power-parameter sensors 202 (“second sensor 202”), the sensors 200, 202 being configured to sense one or more parameters of power on the grid connections 114a, 114b, respectively.

[0041] The UPS 201 includes a first main input 204, a second main input 206, an output 208, an energy- storage-device connection 210 (which may be referred to as an energy-storage-device input 210), a first switch 212, a second switch 214, a third switch 216, a bypass switch 218, a bidirectional AC / DC converter 220 (which may also act as a DC / AC converter, but which may be referred to as an AC / DC converter 220 for simplicity), a DC / AC converter 222, a DC / DC converter 224, one or more third power-parameter sensors 226 (“third sensor 226”), and at least one controller 228 (“controller 228”). In some examples, the UPS 201 includes one or more energy- storage devices 230 (“energy-storage device 230”), which may include, for example, a battery. In other examples, the energy-storage device 230 may be coupled to the UPS 201 via the energy- storage-device connection 210, but may not be part of the UPS 201.

[0042] The first input 204 is coupled to the first grid connection 114a and to the first switch 212. The second input 206 is coupled to the second grid connection 114b and to the third switch 216. The output 208 is coupled to the bypass switch 218 and the DC / AC converter 222 via the third sensor 226, and is configured to be coupled to the UPS loads 104. The cncrgy-storagc-dcvicc connection 210 is coupled to the DC / DC converter 224, and is configured to be coupled to the energy- storage device 230.

[0043] The first switch 212 is coupled to the first input 204 at a first connection, and is coupled to the second switch 214 and the AC / DC converter 220 at a second connection. The second switch 214 is coupled to the first switch 212 and the AC / DC converter 220 at a first connection, and is coupled to the third switch 216 and the bypass switch 218 at a second connection. The third switch 216 is coupled to the second input 206 at a first connection, and is coupled to the second switch 214 and the bypass switch 218 at a second connection. The bypass switch 218 is coupled to the second switch 214 and the third switch 216 at a first connection (and to the first input 204 and the second input 206 via the switches 212-216), and is coupled to the DC / AC converter 222 and the output 208 at a second connection. The bypass switch 218 may be considered to be coupled in parallel with the AC / DC converter 220 and the DC / AC converter 222.

[0044] The AC / DC converter 220 is coupled to the first switch 212 and the second switch 214 at a first connection, and is coupled to the DC / AC converter 222 and the DC / DC converter 224 at a second connection. The DC / AC converter 222 is coupled to the AC / DC converter 220 and the DC / DC converter 224 at a first connection, and is coupled to the bypass switch 218 and the output 208 at a second connection. The DC / DC converter 224 is coupled to the AC / DC converter 220 and the DC / AC converter 222 at a first connection, and is coupled to the energy-storage- device connection 210 at a second connection. The controller 228 is configured to be communicatively coupled to the sensors 200, 202, 226, the switches 212-218, and the converters 220-224.

[0045] The non-UPS loads 106a, 106b may be coupled between the inputs 204, 206 and the power sources 108, 110, and may therefore be referred to as upstream loads (that is, upstream of the UPS 201).

[0046] FIG. 3 illustrates a process 300 of operating the UPS 201 according to an example. In at least one example, the process 300 may be executed at least in part by the controller 228. In some examples, the process 300 may be executed repeatedly throughout operation of the UPS 201. At act 302, the controller 228 determines one or more power parameters. The power parameters may include parameters indicative of power received from the power sources 108, 110, and / or provided to the UPS loads 104 at the output 208. For example, the sensors 200, 202, 226 may include current and / or voltage sensors, and act 302 may include the controller 228 receiving current and / or voltage information from one or more of the sensors 200, 202, 226.

[0047] At act 304, the controller 228 determines if acceptable input power is available. For example, the controller 228 may determine if acceptable input power is available from the first power source 108 and / or the second power source 110. The controller 228 may determine if input power provided by the power sources 108, 110 is acceptable based on power parameters received at act 302 from the sensors 200, 202.

[0048] Input power received from the power sources 108, 110 may be considered acceptable if, for example, one or more parameters of the input power fall within accepted ranges of values. For example, input power may be considered acceptable if a voltage of the input power falls within an acceptable range of voltage values. If the input power is not acceptable (304 NO), such as by having a voltage value that falls outside of an acceptable range of values, then the process 300 continues to act 306.

[0049] At act 306, the UPS 201 operates in a backup mode. In the backup mode, the controller 228 may operate the UPS 201 to draw power from the energy-storage device 230 at least because acceptable input power is not available from the inputs 204, 206. For example, the controller 228 may operate the DC / DC converter 224 to draw DC power from the energy-storage device 230 via the energy-storage-device connection 210, convert the DC power to converted DC power, provide the converted DC power to the DC / AC converter 222, and control the DC / AC converter 222 to convert the converted DC power to AC power and provide the AC power to the UPS loads 104 via the output 208. In some examples, the controller 228 may also control the AC / DC converter 220 to draw the converted DC power from the DC / DC converter 224, convert the converted DC power to AC power, and provide the AC power to the UPS loads 104 via the second switch 214, the bypass switch 218, and the output 208 in parallel with the DC / AC converter 222. During the backup mode, the controller 228 may control the switches 212, 216 to be in an open and non-conducting state, and may control the switches 214, 218 to be closed and conducting. The process 300 then returns to act 302. Returning to act 304, if the controller 228 determines that acceptable input power is available (304 YES), then the process 300 continues to act 308.

[0050] At act 308, the controller 228 determines whether to operate in a bypass mode. In the bypass mode, input power received from one or both of the power sources 108, 110 may be provided directly to the UPS loads 104 via the bypass switch 218, bypassing the converters 220- 224. Because the power may not be processed by the converters 220-224 before reaching the UPS loads 104, the controller 228 may operate in the bypass mode only if power is of sufficiently high quality. Accordingly, act 308 may include the controller 228 determining if one or more parameters of the power provided by the power sources 108, 110 falls within certain ranges (for example, tighter ranges of voltage values than the examples discussed above with respect to act 304).

[0051] If the controller 228 determines that the UPS 201 should not operate in bypass mode (308 NO), then the process 300 continues to act 310.

[0052] At act 310, the controller 228 controls the UPS 201 in a normal mode. In the normal mode, the controller 228 controls the bypass switch 218 to be in an open and non-conducting position. The controller 228 controls the AC / DC converter 220 to draw AC power from the input 204 and / or the input 206, controls the AC / DC converter 220 to convert the AC power to DC power and provide the DC power to the DC / AC converter 222, and controls the DC / AC converter 222 to convert the DC power to AC power and provide the AC power to the output 208. The controller 228 may also control the DC / DC converter 224 to draw DC power from the AC / DC converter 220 to recharge the energy- storage device 230 in some examples. The process 300 then returns to act 302.

[0053] Returning to act 308, if the controller 228 determines that the UPS 201 should operate in the bypass mode (308 YES), then the process 300 continues to act 312.

[0054] At act 312, the controller 228 operates the UPS 201 in the bypass mode. During the bypass mode, the controller 228 controls the bypass switch 218 to be in a closed and conducting position. The second power source 110 may provide power directly to the UPS loads 104 via the bypass switch 218, bypassing the converters 220-224. In addition, the controller 228 may operate one or more of the converters 220-224 to provide compensation power provided by the power sources 108, 110 and / or power provided to the UPS loads 104. An example of the bypass mode is provided below with respect to FIG. 4. FIG. 4 illustrates a process 400 of operating the UPS 201 in a bypass mode according to an example. The process 400 may be executed at least in part by the controller 228. The process 400 may provide an example of act 312 of the process 300.

[0055] At optional act 402, the controller 228 may determine one or more power parameters. The controller 228 may determine the power parameters by receiving power-parameter information from one or more of the sensors 200, 202, 226. The power parameters may include parameters indicative of power sensed by the sensors 200, 202, 226, such as current information, voltage information, and so forth.

[0056] For example, optional act 402 may include the controller 228 receiving current information from the first current sensor 200 indicative of harmonics and / or a reactive component in power provided by the first power source 108, and / or receiving current information from the second current sensor 202 indicative of harmonics and / or reactive power provided by the second power source 110, and / or receiving current information from the third current sensor 226 indicative of harmonics and / or reactive power provided to the UPS loads 104, and / or other power parameters.

[0057] The controller 228 may determine whether to provide compensation current based on the power parameters. In some examples, optional act 402 may not be executed, and the controller 228 may determine whether to provide compensation current based on the power parameters obtained at act 302. In other examples, the controller 228 may execute optional act 402 in addition to act 302. Act 402 may include obtaining the same or different types of power parameters than at act 302.

[0058] At act 404, the controller 228 determines whether to provide compensation for both of the non-UPS loads 106a, 106b. As discussed above, each of the loads 104, 106a, 106b may include non-linear loads which may draw non-linear current from the power sources 108, 110. In some examples, the UPS 201 may provide compensation for the UPS loads 104 based on power parameters received from the third sensor 226, but may determine whether to provide compensation for the non-UPS loads 106a, 106b based on the harmonics present in power provided by the power sources 108, 110.

[0059] The UPS 201 may compensate for the non-linear current by determining a current waveform provided by the power sources 108, 110 (for example, based at least in part on power parameters provided by the sensors 200, 202), identifying harmonics present in the waveform which cause the current waveform to deviate from an ideal (for example, perfectly sinusoidal) current waveform, and injecting current into, or absorbing current from, the power sources 108, 110 such that a net current waveform on the grid connections 114a, 114b is closer to the ideal current waveform.

[0060] Act 404 may include the controller 228 determining a harmonic content of power received from the power sources 108, 110, comparing the harmonic content to one or more threshold values, and determining whether to provide compensation based on the harmonic content. For example, the controller 228 may receive current information from each of the sensors 200, 202, decompose the current information, extract harmonic parameters such as reactive power, a third harmonic, a fifth harmonic, a seventh harmonic, and so forth, and compare the extracted information with one or more thresholds.

[0061] If the controller 228 determines that the harmonic content of both of the power sources’ 108, 110 power exceeds the respective thresholds, the controller 228 may determine that compensation should be provided for both of the non-UPS loads 106a, 106b. If the controller 228 determines that compensation should be provided to both of the power sources 108, 110 (404 YES), then the process 400 continues to act 406.

[0062] At act 406, the controller 228 controls the UPS 201 to provide power compensation to both of the power sources 108, 110 based on the non-linearity of the non-UPS loads 106a, 106b. FIG. 5 illustrates a block diagram of the power system 100 in an example in which the UPS 201 is providing power compensation to both of the power sources 108, 110. At act 406, the controller 228 controls the first switch 212, the third switch 216, and the bypass switch 218 to be closed and conducting. The controller 228 controls the second switch 214 to be open and nonconducting. The second power source 110 provides load power directly to the UPS loads 104 via the third switch 216 and the bypass switch 218.

[0063] As illustrated in FIG. 5, the controller 228 further controls the converters 220-224 to provide compensation current to the power sources 108, 110. Controlling the converters 220-224 may include outputting a signal that causes one or more of the converters 220-224 to generate a compensation current based on one or more power parameters, wherein the compensation current increases a linearity of power delivered to at least one load (for example, one or more of the loads 104, 106a, 106b). The first power source 108 may receive compensation due to non- linearities introduced by the first non-UPS loads 106a, and the second power source 110 may receive compensation due to non-linearities introduced by the UPS loads 104 and / or the second non-UPS loads 106b.

[0064] The controller 228 controls the bi-directional AC / DC converter 220 and / or the DC / DC converter 224 to provide compensation to the first power source 108. For example, the controller 228 may output a signal to the AC / DC converter 220 that causes the AC / DC converter 220 to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to at least one load (for example, one or more of the loads 104, 106a, 106b). The AC / DC converter 220 may generate the compensation current at least in part using energy derived from the energy- storage device 230.

[0065] A first trace 500 indicates a path of compensation current between the AC / DC converter 220 and the first power source 108. The AC / DC converter 220 may draw current from the first power source 108 and / or may inject current to the first power source 108 (for example, derived from the energy-storage device 230) along the first trace 500. The first trace 500 is depicted with a bi-directional arrow to indicate that current may be drawn from, or injected to, the first power source 108. The direction and magnitude of the compensation current along the first trace 500 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the first power source 108 and sensed by the first sensor 200 as determined by the controller 228.

[0066] The controller 228 also controls the DC / AC converter 222 and / or the DC / DC converter 224 to provide compensation to the second power source 110 and / or the UPS loads 104. A second trace 502 indicates a path of compensation current between the DC / AC converter 222 and the second power source 110. The DC / AC converter 222 may draw current from the second power source 110 and / or may inject current to the second power source 110 (for example, derived from the energy-storage device 230) along the second trace 502. The second trace 502 is depicted with a bi-directional arrow to indicate that current may be drawn from, or injected to, the second power source 110. The direction and magnitude of the compensation current along the second trace 502 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the second power source 110 and sensed by the second sensor 202 and / or the third sensor 226 as determined by the controller 228.

[0067] Accordingly, at act 406 the controller 228 may control the UPS 201 to provide power compensation to both of the power sources 108, 110. In some examples, the compensation current may be derived at least in part from energy stored in the energy-storage device 230. Returning to act 404, if the controller 228 determines that compensation should not be provided to both power sources 108, 110 (for example, because a harmonic content of the power provided by each of the power sources 108, 110 is not above respective thresholds) (404 NO), then the process 400 continues to act 408.

[0068] At act 408, the controller 228 determines whether to provide power compensation to the first power source 108 due to the first non-UPS loads 106a, but not to the second power source 110 due to the second non-UPS loads 106b. For example, the controller 228 may determine whether the harmonic content of the power provided by the first power source 108 is above a threshold value. The controller 228 may determine that the harmonic content of the power provided by the second power source 110 is not above a threshold value, which may indicate that the harmonic distortion of the second non-UPS loads 106b is relatively low; in some examples, however, the UPS 201 may provide compensation to the second power source 110 due to nonlinearity of the UPS loads 104 even if no compensation is provided due to the non-linearity of the second non-UPS loads 106b. If the controller 228 determines that power compensation should be provided to the first power source 108 due to the first non-UPS loads 106a, but that power compensation is not necessary to the second power source 110 due to the second non-UPS loads 106b, then the process 400 continues to act 410.

[0069] At act 410, the controller 228 controls the UPS 201 to provide power compensation to the first power source 108 due to the first non-UPS loads 106a. FIG. 6 illustrates a block diagram of the power system 100 in an example in which the UPS 201 is providing power compensation to the first power source 108 due to the non-UPS loads 106b. At act 410, the controller 228 controls the first switch 212, the third switch 216, and the bypass switch 218 to be closed and conducting. The controller 228 controls the second switch 214 to be open and non-conducting. The second power source 110 provides load power directly to the UPS loads 104 via the third switch 216 and the bypass switch 218.

[0070] As illustrated in FIG. 6, the controller 228 further controls the AC / DC converter 220 and / or the DC / DC converter 224 to provide compensation current to the first power source 108. In some examples, the controller 228 may also control the DC / AC converter 222 and / or the DC / DC converter 224 to provide compensation current to the second power source 110. Controlling the respective converters may include outputting a signal that causes the respective converters to generate a compensation current based on the one or more power parameters. The compensation current may be generated at least in part using energy derived from the energystorage device 230. The first power source 108 may receive compensation due to non-linearities introduced by the first non-UPS loads 106a, and the second power source 110 may receive compensation due to non-linearities introduced by the UPS loads 104.

[0071] The controller 228 controls the bi-directional AC / DC converter 220 and / or the DC / DC converter 224 to provide compensation to the first power source 108. A first trace 600 indicates a path of compensation current between the AC / DC converter 220 and the first power source 108. The AC / DC converter 220 may draw current from the first power source 108 and / or may inject current to the first power source 108 along the first trace 600. The first trace 600 is depicted with a bi-directional arrow to indicate that current may be drawn from, or injected to, the first power source 108. The direction and magnitude of the compensation current along the first trace 600 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the first power source 108 and sensed by the first sensor 200 as determined by the controller 228.

[0072] In some examples, the controller 228 may also control the DC / AC converter 222 and / or the DC / DC converter 224 to provide compensation to the second power source 110 due to the UPS loads 104. A second trace 602 indicates a path of compensation current between the DC / AC converter 222 and the second power source 110 and / or the UPS loads 104. The DC / AC converter 222 may draw current from the second power source 110 and / or may inject current to the second power source 110 along the second trace 602. The second trace 602 is depicted with a bidirectional arrow to indicate that current may be drawn from, or injected to, the second power source 110. The direction and magnitude of the compensation current along the second trace 602 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the second power source 110 and sensed by the second sensor 202 and / or the third sensor 226 as determined by the controller 228.

[0073] In various examples, the controller 228 may not control the converters 222, 224 to provide compensation to the second power source 110. For example, the UPS 201 may not provide compensation to the second power source 110 if neither the second non-UPS loads 106b nor the UPS loads 104 distort the power quality on the second grid connection 114b above a threshold amount. The second trace 602 is illustrated in dashed lines to indicate that, in some examples, the UPS 201 provides power compensation to the first power source 108 but not to the second power source 110.

[0074] Accordingly, at act 410 the controller 228 may control the UPS 201 to provide power compensation to the first power source 108 due to non-linearities of the first non-UPS loads 106a. In some examples, the controller 228 may also provide compensation to the second power source 110 due to non-linearities of the UPS loads 104, even if the second non-UPS loads 106b may not substantially affect the power on the second grid connection 114b. Returning to act 408, if the controller 228 determines that compensation should not be provided to the first power source 108 (for example, because a harmonic content of the power provided by the first power source 108 is not above a threshold) (408 NO), then the process 400 continues to act 412.

[0075] At act 412, the controller 228 determines whether to provide power compensation to the second power source 110 due to the second non-UPS loads 106b, but not to the first power source 108 due to the second non-UPS loads 106b. As discussed above, the controller 228 may determine at act 408 - NO that the harmonic content of the power provided by the first power source 108 is not above a threshold value, which may indicate that the harmonic distortion of the first non-UPS loads 106a is relatively low and that no compensation is required. However, the controller 228 may determine that the harmonic content of the power provided by the second power source 110 is above a threshold value. If the controller 228 determines that power compensation should be provided to the second power source 110 due to the second non-UPS loads 106b and / or the UPS loads 104, but that power compensation is not necessary to the first power source 108, then the process 400 continues to act 414.

[0076] At act 414, the controller 228 controls the UPS 201 to provide power compensation to the second power source 110 due to the second non-UPS loads 106b. FIG. 7 illustrates a block diagram of the power system 100 in an example in which the controller 228 is providing power compensation to the second power source 110, but not to the first power source 108. At act 414, the controller 228 controls the second switch 214, the third switch 216, and the bypass switch 218 to be closed and conducting. The controller 228 controls the first switch 212 to be open and non-conducting. The second power source 110 provides load power directly to the UPS loads 104 via the third switch 216 and the bypass switch 218.

[0077] As illustrated in FIG. 7, the controller 228 further controls the converters 220-224 to provide compensation current to the second power source 110. Controlling the respective converters may include outputting a signal that causes the respective converters to generate a compensation current based on the one or more power parameters. The converters 220, 222 may provide compensation to the second power source 110 in parallel. A first trace 700 indicates a path of compensation current between the AC / DC converter 220 and the second power source 110 and / or the UPS loads 104. The AC / DC converter 220 may draw current from the second power source 110 and / or may inject current to the second power source 110 along the first trace 700. The first trace 700 is depicted with a bi-directional arrow to indicate that current may be drawn from, or injected to, the second power source 110. The direction and magnitude of the compensation current along the first trace 700 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the second power source 110 and sensed by the second sensor 202 and / or the third sensor 226 as determined by the controller 228.

[0078] A second trace 702 indicates a path of compensation current between the DC / AC converter 222 and the second power source 110 and / or the UPS loads 104. The AC / DC converter 222 may draw current from the second power source 110 and / or may inject current to the second power source 110 along the second trace 702. The second trace 702 is depicted with a bidirectional arrow to indicate that current may be drawn from, or injected to, the second power source 110. The direction and magnitude of the compensation current along the second trace 702 may be based on a difference between an ideal current waveform and the actual current waveform of power provided by the second power source 110 and sensed by the second sensor 202 and / or the third sensor 226 as determined by the controller 228.

[0079] Accordingly, at act 414 the controller 228 may control the UPS 201 to provide power compensation to the second power source 110, and not the first power source 108, due to nonlinearities of the second non-UPS loads 106b and / or the UPS loads 104. The process 400 then returns to act 402.

[0080] Returning to act 412, if the controller 228 determines that compensation should not be provided to the second power source 110 (for example, because a harmonic content of the power provided by the second power source 110 is not above a threshold) (412 NO), then the process 400 returns to act 402.

[0081] Accordingly, in some examples, if the controller 228 determines that neither of the power sources 108, 110 require power compensation (404 - NO, 408 - NO, 412 - NO) due to the non- UPS loads 106a, 106b, then the UPS 201 may not provide power compensation to either of the power sources 108, 110. In some examples, the controller 228 may operate the UPS 201 to provide power compensation to the second power source 110 to compensate for non-linearities of the UPS loads 104 regardless of whether or not the non-linearities introduced by the non-UPS loads 106a, 106b are substantial.

[0082] In some examples, acts 404, 408, and 412 are illustrated as occurring sequentially for purposes of explanation. In various implementations, the controller 228 may not execute the determinations of acts 404, 408, and 412 sequentially as indicated in the process 400, but rather may determine which power sources to compensate in one instance. For example, the controller 228 may compare a harmonic content of power received from both of the power sources 108, 110 to respective thresholds at substantially the same time, and may then select a mode of operation based on those comparisons. Accordingly, acts 404, 408, and 412 may be illustrated as separate acts for purposes of explanation rather than limitation.

[0083] As discussed above, the UPS 201 of FIG. 2 provides an example of the UPS 102 in which the UPS 201 may be coupled to two power sources 108, 110. The principles of the disclosure are applicable to additional examples of the UPS 102 in which the UPS 102 is coupled to more than two power sources, or to a single power source. For example, the second power source 110 may be omitted or may be unable to provide power (for example, due to a blackout condition) such that the UPS 102 is receiving power from only a single power source, such as the first power source 108.

[0084] FIG. 8 illustrates a block diagram of a power system 800 according to an example. The power system 800 includes a UPS 802 in a bypass mode. The power system 800 may be an example of the power system 100, and the UPS 802 may be an example of the UPS 102. The power system 800 is similar to the power system 100; however, the second power source 110 (and the second non-UPS loads 106b) is not present. For example, the second power source 110 may not be implemented in the power system 800 or may be temporarily unavailable, such as due to a blackout condition.

[0085] The UPS 802 may otherwise be similar to the UPS 201, except that the third switch 216 may be omitted (or may be open and non-conducting because the second power source 110 is temporarily unavailable, for example). In some examples, either the second switch 214 or the bypass switch 218 may also be omitted. In the bypass mode of FIG. 8, the controller 228 controls the switches 212, 214, 218 to be closed and conducting such that power from the first power source 108 is provided directly to the UPS loads 104, thereby bypassing the converters 220-224.

[0086] The controller 228 may also control the converters 220-224 to provide compensation to the first power source 108 to address non-linearities introduced by the UPS loads 104 and / or the first non-UPS loads 106a. For example, the controller 228 may receive power-parameter information from the first sensor 200 and the third sensor 226 to determine how the power provided by the first power source 108 deviates from a desired waveform (for example, an ideal sinusoidal waveform). The controller 228 may control the converters 220, 222 to provide compensation to the first power source 108 in parallel.

[0087] A first trace 804 indicates a path of compensation provided by the AC / DC converter 220 to the first power source 108 and / or the UPS loads 104. The controller 228 controls the AC / DC converter 220 and / or the DC / DC converter 224 to inject current to, or absorb current from, the first power source 108 via the first switch 212. A second trace 806 indicates a path of compensation provided by the DC / AC converter 222 to the first power source 108 and / or the UPS loads 104. The controller 228 controls the DC / AC converter 222 and / or the DC / DC converter 224 to inject current to, or absorb current from, the first power source 108 via the bypass switch 218 and the second switch 214. The controller 228 therefore controls the converters 220, 222 to provide compensation in parallel to the first power source 108.

[0088] Accordingly, in various examples of the disclosure the UPS 102 may provide compensation to the first power source 108 and / or the second power source 110 due to nonlinearities of not only the UPS loads 104, but also the non-UPS loads 106. As discussed above, the controller 228 may control the converters 220-224 to provide compensation current to (or absorb current from) the power sources 108 and / or 110 such that the current provided by the power sources 108 and / or 110 are more similar to a desired waveform, such as an ideal sinusoidal waveform.

[0089] FIG. 9 illustrates a graph 900 depicting an example of how a desired compensation current is determined according to an example. An ideal trace 902 indicates a desired waveform for current provided by a given power source, which may be an ideal sinusoidal waveform. A non-linear trace 904 indicates a non-linear- load current drawn by a non-linear load, such as the UPS loads 104 and / or the non-UPS loads 106. The controller 228 may determine the non-linear- load current based on information received from one or more of the sensors 200, 202, 226. The controller 228 may then determine a difference between the waveforms indicated by the traces 902, 904 and invert the resulting waveform. A compensation trace 906 indicates the resulting inverted waveform, which represents the compensation current which may be provided by (or absorbed by) the UPS 102. Stated differently, a sum of the waveforms indicated by the traces 904, 906 may be the ideal trace 902, such that providing the compensation indicated by the compensation trace 906 causes the current of a compensated power source to approach the ideal trace 902.

[0090] In some examples, two or more UPSs may be coupled in parallel with each other and to one or more power sources and one or more UPS loads. One of the UPSs may be a primary UPS that operates in substantially the same or a similar manner as the example UPSs discussed above. Another one or more of the UPSs may be a backup UPS that provides compensation to the one or more power sources in any mode of operation (for example, if the primary UPS is in a normal mode, or a backup mode, or a bypass mode). If the primary UPS fails or additional output capacity is desired, the secondary UPS(s) may be hot-swapped to provide power to the one or more UPS loads.

[0091] FIG. 10 illustrates a block diagram of a power system 1000 with multiple UPSs according to an example. The power system 1000 includes a first UPS 1002a, which is arbitrarily considered a primary UPS, and a second UPS 1002b, which is arbitrarily considered a secondary UPS. In the illustrated example, the first UPS 1002a may be in a normal mode of operation. The second UPS 1002b may not be providing load power to the UPS loads 104, and may be in a compensation mode of operation in which the second UPS 1002b is controlled to provide compensation to the first power source 108 and the UPS loads 104. The components of the UPSs 1002a, 1002b may be substantially similar to those of the UPS 201, and like components are labeled accordingly, with a suffix “a” indicating that the component corresponds to the first UPS 1002a, and a suffix “b” indicating that the component corresponds to the second UPS 1002b.

[0092] The first controller 228a of the first UPS 1002a controls the first switch 212a to be closed and conducting, and controls the second switch 214a and the third switch 216a to be open and non-conducting. The first controller 228a controls the first converters 220a, 222a to provide power drawn from the first power source 108 to the UPS loads 104.

[0093] The second controller 228b of the second UPS 1002b controls the first switch 212b to be closed and conducting, and controls the second switch 214b and the third switch 216b to be open and non-conducting. The second controller 228b controls the second converters 220b, 222b to provide compensation to the first power source 108 and the UPS loads 104, respectively. For example, the second controller 228b may receive power-parameter information from the first sensor 200 the third sensor 226a, and / or the third sensor 226b to determine compensation to provide to the first power source 108 and / or the UPS loads 104. The second controller 228b then controls the second AC / DC converter 220b to provide compensation to the first power source 108 as indicated by a first trace 1004, and controls the second DC / AC converter 222b to provide compensation to the UPS loads 104 as indicated by a second trace 1006. Moreover, if the first UPS 1002a becomes unavailable or is unable to meet the load requirements of the UPS loads 104, then the second UPS 1002b may transition to providing load power to the UPS loads 104.

[0094] Additional examples are within the scope of the disclosure. For example, some examples of the UPS 102 may include a bi-directional AC / DC converter, a DC / DC converter, and a DC / AC converter, such as the converters 220-224, which may be collectively referred to as a power module. In some examples, UPSs may include multiple power modules each having a bidirectional AC / DC converter, a DC / DC converter, and a DC / AC converter coupled in parallel. Implementing multiple power modules in parallel may enable the UPS to increase or decrease power capacity by adding or removing power modules.

[0095] Various controllers, such as the controller 228, may execute various operations discussed above. The controller 228 may also execute one or more instructions stored on one or more non- transitory computer-readable media, which the controller 228 may include and / or be coupled to, which may result in manipulated data. The non-transitory computer-readable media may include memory and / or storage. In some examples, the controller 228 may include one or more processors or other types of controllers. In one example, the controller 228 is or includes at least one processor. In another example, the controller 228 performs at least a portion of the operations discussed above using an application-specific integrated circuit tailored to perform particular operations in addition to, or in lieu of, a processor. As illustrated by these examples, examples in accordance with the present disclosure may perform the operations described herein using many specific combinations of hardware and software and the disclosure is not limited to any particular combination of hardware and software components. Examples of the disclosure may include a computer-program product configured to execute methods, processes, and / or operations discussed above. The computer-program product may be, or include, one or more controllers and / or processors configured to execute instructions to perform methods, processes, and / or operations discussed above.

[0096] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of, and within the spirit and scope of, this disclosure. Accordingly, the foregoing description and drawings are by way of example only.

[0097] What is claimed is:

Claims

CLAIMS1. An uninterruptible power supply (UPS) comprising: at least one main input; an energy- storage-device input; an output; a bi-directional AC / DC converter; a DC / AC converter; and at least one controller configured to determine one or more power parameters indicative of at least one power source powering at least one load, and output a signal that causes the bi-directional AC / DC converter to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

2. The UPS of claim 1, wherein the output is configured to be coupled to a UPS load, and wherein the at least one load includes the UPS load.

3. The UPS of claim 1, wherein the at least one power source includes a mains source, and wherein the at least one main input is configured to receive power from the mains source, and wherein the at least one load includes an upstream load coupled between the at least one main input and the mains source.

4. The UPS of claim 1, wherein the energy-storage-device input is configured to be coupled to at least one energy- storage device, and wherein the at least one controller is further configured to cause the bi-directional AC / DC converter to generate the compensation current using energy derived from the at least one energy-storage device.

5. The UPS of claim 1, further comprising at least one bypass switch coupled to the at least one main input at a first connection and to the output at a second connection, the at least one bypass switch being coupled in parallel with the bi-directional AC / DC converter and the DC / AC converter.

6. The UPS of claim 5, wherein the at least one controller is further configured to control the at least one bypass switch to selectively conduct power from the at least one main input to the output, bypassing the bi-directional AC / DC converter and the DC / AC converter.

7. The UPS of claim 1, wherein the at least one controller is further configured to output a second signal that causes the DC / AC converter to generate a second compensation current based on the one or more power parameters, wherein the second compensation current increases the linearity of power delivered to one or more loads.

8. The UPS of claim 1, wherein the at least one main input includes a first input, the UPS further comprising: a first switch coupled to the first input; and a second switch coupled between the bi-directional AC / DC converter and the output.

9. The UPS of claim 8, wherein the bi-directional AC / DC converter is configured to provide a first portion of the compensation current to a first load via the first switch, and is configured to provide a second portion of the compensation current to a second load via the second switch.

10. The UPS of claim 8, wherein the at least one main input further includes a second input, the UPS further comprising a third switch coupled to the second input.

11. The UPS of claim 8, further comprising a bypass switch coupled between the second switch and the output.

12. The UPS of claim 1, wherein the at least one main input includes: a first input configured to be coupled to a first power source, and a second input configured to be coupled to a second power source.

13. At least one non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power supply including a bi-directional AC / DCconverter, the sequences of computer-executable instructions including instructions that instruct at least one processor to: determine one or more power parameters indicative of at least one power source powering at least one load, and output a signal that causes the bi-directional AC / DC converter to generate a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

14. The at least one non-transitory computer-readable medium of claim 13, wherein the power supply is further configured to be coupled to at least one energy-storage device, and wherein the instructions further instruct at least one processor to cause the bi-directional AC / DC converter to generate the compensation current using energy derived from the at least one energy-storage device.

15. The at least one non-transitory computer-readable medium of claim 13, wherein the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, wherein the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a portion of the compensation current to the upstream load.

16. The at least one non-transitory computer-readable medium of claim 13, wherein the power supply further includes an output configured to be coupled to a UPS load, wherein the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a first portion of the compensation current to the UPS load.

17. The at least one non-transitory computer-readable medium of claim 16, wherein the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, wherein the instructions further instruct at least one processor to control the bi-directional AC / DC converter to provide at least a second portion of the compensation current to the upstream load.

18. A method of operating a power supply including a bi-directional AC / DC converter, the method comprising: determining one or more power parameters indicative of at least one power source powering at least one load, and generating, by the bi-directional AC / DC converter, a compensation current based on the one or more power parameters, wherein the compensation current increases a linearity of power delivered to the at least one load.

19. The method of claim 18, wherein the power supply further includes a first input configured to be coupled to at least one power source and to an upstream load, the method further comprising providing, by the bi-directional AC / DC converter, at least a portion of the compensation current to the upstream load.

20. The method of claim 18, wherein the power supply further includes an output configured to be coupled to a UPS load, the method further comprising providing, by the bi-directionalAC / DC converter, at least a first portion of the compensation current to the UPS load.

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