Staged power converter for distributed energy sources

Abstract

A multi-staged alternating current (AC) / direct current (DC) converter specifically tuned for pulse-based, rapidly varying energy input from a distributed energy source is described. The converter may include a plurality of switches and inverters, each inverter having a different range. The converter may be configured to switch between the bands based on sudden changes in voltage and / or current inputs from the distributed energy source.

Description

[0001] STAGED POWER CONVERTER FOR DISTRIBUTED ENERGY SOURCES

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 562,838 filed on March 8, 2024, the contents of which are incorporated herein by reference in their entirety.

[0004] CONTRACTUAL ORIGIN

[0005] This invention was made with government support under Contract No. DE-AC36- 08G028308 awarded by the Department of Energy. The government has certain rights in this invention.

[0006] BACKGROUND

[0007] Commercially available power converters are designed with power, current, and voltage ratings. If attempting to operate significantly below these ratings, the converter will not function. However, operating significantly over these ratings (e.g., greater than approximately 150% of its rating) will result in catastrophic failure of the converter. Unlike most distributed generation systems (wind, hydro, gas turbine etc.), wave energy operates in a highly randomized, pulsed based manner with peak to average current and voltage ratios often in excess of about 4: 1. As there are no commercial solutions capable of this wide operational band developers are left with two options: 1) to oversize the converter which, in addition to increasing costs, results in lower efficiencies when below rated performance, or 2) to undersize the converter which limits the peak power and reduces overall energy production but also risks catastrophic failure should power levels be greatly exceeded. Additionally, as distributed energy sources are highly varied in operation requiring complicated control processes, existing converters are generally unsuitable due to their response speed. Thus, there remains a need for power converters that can handle abrupt and significant performance changes.

[0008] SUMMARY

[0009] An aspect of the present disclosure is a staged active rectifier device including a controller, a first rectifier connected to a first switch, and a second rectifier connected to a second switch, wherein the first rectifier has a first range, the controller is configured to receive an input describing a performance metric of a distributed energy source, the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, and the first rectifier is configured to produce an output. In some embodiments, the second rectifier has a second range, the controller is configured to instruct the first switch to deactivate the first rectifier when the performance metric is within the second range, and the controller is configured to instruct the second switch to activate the second rectifier when the performance metric is within the second range. In some embodiments, the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, and the controller is configured to instruct the second switch to deactivate the second rectifier when the performance metric is within the first range. In some embodiments, the distributed energy source includes at least one of a photovoltaic cell, a wave energy converter, or a wind turbine. In some embodiments, the performance metric includes a power generation rate. In some embodiments, the input includes an alternating current (AC) or direct current (DC). In some embodiments, the output includes an alternating current (AC).

[0010] An aspect of the present disclosure is an integrated combined energy box (ICEBOX) system, the system including a staged active rectifier configured to generate an output, the staged active rectifier including a first controller, a first rectifier connected to a first switch, and a second rectifier connected to a second switch, in which the first rectifier has a first range, the first controller is configured to receive an input describing a performance metric of a distributed energy source, the first controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, an energy storage device configured to receive the output and store an amount of energy, a second controller configured to communicate with the staged active rectifier, the energy storage device, or the terminal, the second controller is configured to instruct the energy storage device to release at least a portion of the amount of energy when a power supply is desired. In some embodiments, the second rectifier has a second range, the controller is configured to instruct the first switch to deactivate the first rectifier when the performance metric is within the second range, and the controller is configured to instruct the second switch to activate the second rectifier when the performance metric is within the second range. In some embodiments, the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, and the controller is configured to instruct the second switch to deactivate the second rectifier when the performance metric is within the first range. In some embodiments, the distributed energy source includes at least one of a photovoltaic cell, a wave energy converter, or a wind turbine. In some embodiments, the energy storage device includes a battery.

[0011] An aspect of the present disclosure is a method including receiving, using a controller, a first input from a distributed energy source, selecting, using the controller, a first rectifier with a first range containing the first input, activating, using a first switch, the first rectifier, and generating, using the first rectifier, a first output, in which the activating includes the first switch receiving an instruction from the controller. In some embodiments, directing, using the controller, the first output to an energy storage device, and releasing, using the energy storage device, a second output, in which the second output includes at least a portion of the first output. In some embodiments, the first output includes at least one of an alternating current (AC) or a direct current (DC). In some embodiments, the second output includes an alternating current (AC). In some embodiments, the method also includes receiving, using the controller, a second input from the distributed energy source, selecting, using the controller, a second rectifier with a second range containing the second input, deactivating, using the first switch, the first rectifier, activating, using a second switch, the second rectifier, and generating, using the second rectifier, a second output; in which the activating includes the second switch receiving an instruction from the controller. In some embodiments, the first range is less than the second range. In some embodiments, the method also includes directing, using the controller, the second output to an energy storage device, and releasing, using the energy storage device, a third output, in which the third output includes at least a portion of the second output. In some embodiments, the third output includes an alternating current (AC).

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Some embodiments of the present disclosure are illustrated in the referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.

[0014] FIG. 1 illustrates power electronics architecture of a multi-staged alternating current (AC) / direct current (DC) converter, according to some aspects of the present disclosure.

[0015] FIG. 2 illustrates a high-level depiction of a system including a multi-staged AC / DC converter coupled with a DC bus with energy storage coupled with a three-phase inverter, according to some aspects of the present disclosure. FIG. 3 illustrates the structure of an integrated combined energy box (ICE Box) device, according to some aspects of the present disclosure.

[0016] REFERENCE NUMERALS

[0017] 100 system

[0018] 105 distributed energy source

[0019] 110 staged active rectifier

[0020] 115 rectifier

[0021] 120 DC

[0022] 125 switch

[0023] 130 AC

[0024] 135 energy storage

[0025] 140 DC bus

[0026] 145 buck / boost converter

[0027] 150 controller

[0028] 155 inverter

[0029] 200 integrated combined energy box (ICEBOX)

[0030] DETAILED DESCRIPTION

[0031] The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0032] As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.

[0033] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±20%, ±15%, ±10%, ±5%, or ±1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±1%, ±0.9%, ±0.8%, ±0.7%, ±0.6%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, or ±0.1% of a specific numeric value or target.

[0034] Among other things, the present disclosure relates to a multi-staged alternating current (AC) / direct current (DC) converter specifically tuned for pulse-based, rapidly varying energy input from a distributed energy source. Conversion stages may be designed for a band (or range) of operating power to maximize efficiency within that band. The converter may switch between the bands based on sudden changes in voltage and / or current inputs. The present disclosure also includes an Integrated Combined Energy Box (ICE Box) which is an energy integration, energy storage, and energy management system that is compatible with distributed energy sources. Operating as a robust and flexible nano-grid the ICE Box may be capable of converting the power generated by various distributed energy sources and converting that energy into grid quality electrical energy (i.e., about 50-60 Hz about 120V, about 208V and about 480V). The electrical elements of the ICE Box may be contained in a substantially durable container suitable for rapid deployment and extended operation essentially fulfilling the role of a diesel power generator but using other sources of energy.

[0035] FIG. 1 illustrates power electronics architecture of a multi-staged alternating current (AC) / direct current (DC) converter device 110, according to some aspects of the present disclosure. Multiple stages of power electronics may be sized for various power ratings / ranges and connected in parallel. Semiconductor switching devices 125a-c can dispatch the appropriate rectifier 115a-c based on the instantaneous power being produced by the distributed energy source 105 (for example, sudden increases or decreases in the power and / or voltage generated). Each rectifier 115a-c may have a specific range for operation based on the distributed energy source 105. In the exemplary embodiment shown in FIG. 1, rectifier 115a has a range for high power production of the distributed energy source 105, rectifier 115b has a range for average power production of the distributed energy source 105, and rectifier 115c has a range for low power production of the distributed energy source 105. In some embodiments, there may be some overlap in the ranges of the rectifiers 115a-c. This approach may eliminate the compromises necessary for operating a single converter with using a distributed energy source 105, in both device sizing and in circuit topology. The switching devices 125a-c may be controlled by a processor or controller 150 capable of analyzing the input performance metric (such as current or voltage) from the distributed energy source 105 and determining the appropriate rectifier 115 (i.e., a rectifier 115 that has a range that the input current is within). In some embodiments, the processor 150 may be capable of predicting future performance of the distributed energy source 105 and adjusting the switching device 125 preemptively.

[0036] In some embodiments, a distributed energy source 105 may be a technology which generates electricity close to where it is used. Exemplary distributed energy sources 105 may include photovoltai cs, wind turbines, wave energy converters, hydropower turbines, diesel generators, gasoline generators, or other energy generating sources. The present disclosure is generally aimed at distributed energy sources 105 which have a large range of power generation capabilities and may vary greatly in the amount of power generated at any given time. The distributed energy sources 105 may produce power intermittently and / or have significant voltage oscillations in their output. For example, the distributed energy source 105 of a wave energy converter may have substantially large fluctuations in energy generation performance, and these fluctuations may be relatively sudden. The methods and devices described herein may allow for greater collection of the electrical energy generated by such an exemplary distributed energy source 105.

[0037] FIG. 2 illustrates a high-level depiction of a system 100 including a multi-staged AC / DC converter device 110a coupled with a DC bus 140 with energy storage 135 coupled with a staged inverter 1 1 Ob for further AC 130 applications, according to some aspects of the present disclosure. The system 100 may allow for converting AC 130 to DC 120 power from a distributed energy source 105, preparing the DC 120 for storage using the DC bus 140, storing the DC 120 in an energy storage device 135, and then for inverting the DC 120 to AC 130 for use / release. The staged nature of the converter 110a and inverter 110b allow for a larger bandwidth of power generated by the distributed energy source 105 to be stored and utilized, as even power at the higher or lower ends of the performance of the distributed energy source 105 can be stored and utilized.

[0038] In some embodiments, the energy storage device 135 may be a battery, thermal energy storage device, fuel tank, or other device capable of storing energy for periods of time. The energy storage device 135 may be turned on (i.e., instructed to release energy) or turned off (i.e., instructed to store or hold energy) by a controller 150. In some embodiments, the energy storage device 135 may be able to communicate its level of charge (i.e., how much energy it is storing and / or its capacity for storing additional energy) to a controller 150.

[0039] Substantially maximizing the power extraction of distributed energy sources 105 is the objective of the devices 110 and system 100 of the present disclosure. Distributed energy sources 105 produce a unique form of power requiring specialized power electronics and control to maximize efficiency and provide quality power on the output. The structure of an integrated combined energy box (ICEBOX) 200 is shown in FIG. 3. Each distributed energy source 105 may be able to connect to an input on the ICEBOX 200 and the power electronics will adjust accordingly. This may be achieved through the use of custom staged active rectifiers HOa-c followed by a buck / boost stage 145 to accurately control voltage to the DC bus 140. In some embodiments, the multi-stage rectifier 110 of the present disclosure may be combined with the ICEBOX 200. In some embodiments, a separate charge controller 150d may control the energy storage 135. AC inverters 155a-c may provide AC load 120 for use.

[0040] In some embodiments, the ICEBOX 200 may be used with a variety of distributed energy sources 105, even connected to multiple distributed energy sources 105 at the same time. In some embodiments, controllers 150 may continually adjust their input voltage to attempt to draw as much power from the distributed energy source 105 as possible (utilizing maximum Power Point Tracking (MPPT) charge techniques). For example, if the distributed energy source 105a is a photovoltaic cell, it is likely compatible with a buck converter 145, though different topologies may exist. For a distributed energy source 105a that is a photovoltaic, the ICEBOX 200, the DC input 120 may bypass the rectification stage through the body diodes of semiconductor switching devices (see FIG. 3). The following buck / boost stage 145a and / or the controller 150a may perform a MPPT analysis to attempt to extract the maximum power from the distributed energy source 105.

[0041] In some embodiments, for a distributed energy source 105b that is wind power, ICEBOX 200 may also be utilized. For example, wind turbines typically output a substantially steady AC voltage 130. Due to the inertia and adjustable pitch of the blade, variations in wind speed are often not seen as variations of power produced. An active pulse-width modulation (PWM) rectifier 115 rated at approximately the same power as the turbine is rated can be used to feed into the DC bus 140.

[0042] In some embodiments, for a distributed energy source 105c that is a wave energy converter, there are many unique challenges that accompany the power take off (PTO). Unlike other distributed energy sources 105 that have a substantially steady power output, wave energy is almost constantly changing and crossing through zero with the motion of the wave. Additionally, large spikes can occur suddenly, momentarily pushing the voltage out of the generator up. Consequently, the peak-to-average ratio of wave energy can exceed approximately 10:1 or even approximately 20: 1. Rectification of an AC waveform is generally broken into two categories: active and passive. Most rectification for wave energy is done passively, through a three-phase diode rectifier. Diode rectifiers are robust and require no control, however the peak efficiency is around 80% due to the forward voltage of the diodes. In some embodiments, ICEBOX 200 may use staged active rectifiers 110 using and switching devices 125 to improve efficiency and controllability of the rectification stage. Additionally, the use of active control by means of the switching devices 125 can eliminate additional DC / DC conversion stages (i.e., 140) reducing complexity and eliminating another source of power loss.

[0043] In some embodiments, the active staged rectifier 110 and / or ICEBOX 200 may be connected to or include a processor or controller 150, capable of analyzing the power input and sending instructions to adjust the switching devices 125 based on the AC input from the distributed energy source 105. The controller 150 may receive an input of the amount of power generated by the distributed energy source 105 and then may select the rectifier 115 to activate with a switching device 125 based on the amount of power. The controller 150 may adjust the switching devices 125 (and thus which rectifier 115 is utilized) as the power input from the distributed energy source 105 changes. For example, as the power generated by the distributed energy source 105 increases and exceeds the limits of a first rectifier 115a, the controller 150 may adjust the switching devices 125a-b to activate a second rectifier 115b with a higher power range.

[0044] The high peak-to-average ratio of distributed energy sources 105 forces designers to oversize the electronics for a peak power that is rarely seen. The active staged rectifier 110 and / or ICEBOX 200 may address this concern by utilizing stages of rectification (using a plurality of rectifiers 115 and switching devices 125), each designed to maximize output power at distinct ranges of input power.

[0045] In some embodiments, ICEBOX 200 and / or the active staged rectifier 110 of the present disclosure may eliminate the compromises that designers of PTO devices for distributed energy sources 105 face, both in device sizing and in circuit topology. For example, in some embodiments, each power rectifier 115 may utilize a Vienna topology to control power factor and / or increase efficiency whereas the low power topology may include a DC / DC buck / boost stage 145. Each DC / DC buck / boost stagebl45 may be designed exactly as power and voltage levels dictate.

[0046] In some embodiments, ICEBOX 200 may include a custom power electronics for interacting with distributed energy sources 105. In some embodiments, ICEBOX 200 may include the substantially instantaneous changeover between power stages. The use of semiconductor switching devices 125 to switch between power stages may allow for substantially instantaneous adjustment.

[0047] In one or more examples, the techniques described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over, as one or more instructions or code, a computer- readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media, which includes any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to 1) tangible computer-readable storage media, which is non-transitory or 2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and / or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable storage medium. By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transient, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0048] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0049] The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC) or a set of ICs (e.g., a chip set). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a hardware unit or provided by a collection of inter-operative hardware units, including one or more processors as described above, in conjunction with suitable software and / or firmware. The foregoing discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.

Claims

CLAIMSWhat is claimed is:

1. A staged active rectifier device comprising: a controller; a first rectifier connected to a first switch; and a second rectifier connected to a second switch; wherein: the first rectifier has a first range, the controller is configured to receive an input describing a performance metric of a distributed energy source, the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, and the first rectifier is configured to produce an output.

2. The staged active rectifier device of claim 1, wherein: the second rectifier has a second range, the controller is configured to instruct the first switch to deactivate the first rectifier when the performance metric is within the second range, and the controller is configured to instruct the second switch to activate the second rectifier when the performance metric is within the second range.

3. The staged active rectifier device of claim 2, wherein: the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, and the controller is configured to instruct the second switch to deactivate the second rectifier when the performance metric is within the first range.

4. The staged active rectifier device of claim 1, wherein: the distributed energy source comprises at least one of a photovoltaic cell, a wave energy converter, or a wind turbine.

5. The device of claim 1 , wherein: the output comprises an alternating current (AC).

6. An integrated combined energy box (ICEBOX) system, the system comprising: a staged active rectifier configured to generate an output, the staged active rectifier comprising: a first controller; a first rectifier connected to a first switch; and a second rectifier connected to a second switch; wherein: the first rectifier has a first range, the first controller is configured to receive an input describing a performance metric of a distributed energy source, the first controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, an energy storage device configured to receive the output and store an amount of energy; a second controller configured to communicate with the staged active rectifier, the energy storage device, or the terminal, the second controller is configured to instruct the energy storage device to release at least a portion of the amount of energy when a power supply is desired.

7. The system of claim 6, wherein: the second rectifier has a second range, the controller is configured to instruct the first switch to deactivate the first rectifier when the performance metric is within the second range, and the controller is configured to instruct the second switch to activate the second rectifier when the performance metric is within the second range.

8. The system of claim 7, wherein: the controller is configured to instruct the first switch to activate the first rectifier when the performance metric is within the first range, andthe controller is configured to instruct the second switch to deactivate the second rectifier when the performance metric is within the first range.

9. The system of claim 6, wherein: the distributed energy source comprises at least one of a photovoltaic cell, a wave energy converter, or a wind turbine.

10. A method compri sin : receiving, using a controller, a first input from a distributed energy source; selecting, using the controller, a first rectifier with a first range containing the first input; activating, using a first switch, the first rectifier; and generating, using the first rectifier, a first output; wherein: the activating comprises the first switch receiving an instruction from the controller.

11. The method of claim 10, further comprising: directing, using the controller, the first output to an energy storage device; and releasing, using the energy storage device, a second output; wherein: the second output comprises at least a portion of the first output.

12. The method of claim 11, wherein: the first output comprises at least one of an alternating current (AC) or a direct current (DC).

13. The method of claim 10, further comprising: receiving, using the controller, a second input from the distributed energy source; selecting, using the controller, a second rectifier with a second range containing the second input; deactivating, using the first switch, the first rectifier; activating, using a second switch, the second rectifier; and generating, using the second rectifier, a second output; wherein: the activating comprises the second switch receiving an instruction from the controller.

14. The method of claim 13, wherein: the first range is less than the second range.

15. The method of claim 14, further comprising: directing, using the controller, the second output to an energy storage device; and releasing, using the energy storage device, a third output; wherein: the third output comprises at least a portion of the second output.

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