WO2024151743A1

WO2024151743A1 - Power processing and time-varying voltage profile generation

Info

Publication number: WO2024151743A1
Application number: PCT/US2024/011062
Authority: WO
Inventors: Al-Thaddeus Avestruz; Alireza Ramyar; Xiaofan Cui
Original assignee: University of Michigan System
Current assignee: University of Michigan System
Priority date: 2023-01-10
Filing date: 2024-01-10
Publication date: 2024-07-18
Anticipated expiration: 2025-07-10
Also published as: EP4649582A1; CN120814162A; AU2024207273A1

Abstract

A time-varying voltage profile generation device may include a tiered power structure to control flow among multiple power sources. The multiple power source may be coupled into stages each including one or more power sources. Multiple switches of the time-varying voltage profile generation device may selectively couple outputs from individual ones of the stages to generate a time-varying voltage profile.

Description

POWER PROCESSING AND TIME-VARYING VOLTAGE PROFILE GENERATION

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0001] This invention was made with government support under 2146490 awarded by the National Science Foundation. The government has certain rights in the invention.

PRIORITY

[0002] This application claims priority to U.S. Provisional Patent Application No. 63/438,135, filed January 10, 2023, and entitled POWER PROCESSING AND TIME-VARYING VOLTAGE PROFILE GENERATION, which is incorporated by reference herein in its entirety.

BACKGROUND

Technical Field

[0003] The disclosure relates generally to power processing and time-varying voltage profile generation.

Brief Description of Related Technology

[0004] In recent years, green technologies for power generation and storage have undergone widespread adoption. For example, many gigawatts of solar cells were installed in the US alone last year. In another example, advanced power storage installations exceeded the gigawatt threshold in the US in 2020. Forecasts and current incentive systems indicate that this trend of increasing installations will continue in the coming years. Accordingly, there is increasing demand for systems for efficiently and cheaply connecting green technology power nodes (e.g., power sinks and/or power sources) to the grid and for efficiently and cheaply adapting their power output for a variety of other applications. Improvements to power adaption technologies will continue to drive industrial demand.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 shows an example power conversion device.

[0006] Figure 2 shows an example parallel power conversion device. [0007] Figure 3 shows an example time-varying voltage profile generation device.

[0008] Figure 4 shows example voltage profile generation logic.

[0009] Figure 5 shows an example single-switch based time-varying voltage profile generation device.

[0010] Figure 6 shows an example single-switch based time-varying voltage profile generation device with an unfolder circuit.

[0011] Figure 7 shows an example half-bridge based time-varying voltage profile generation device.

[0012] Figure 8 shows an example half-bridge based time-varying voltage profile generation device with an unfolder circuit.

[0013] Figure 9 shows an example full-bridge based time-varying voltage profile generation device.

[0014] Figure 10 shows example parallel tiered structure based time-varying voltage profile generation devices.

[0015] Figure 11A shows an example single-switch based time-varying voltage profile generation device including a clamp circuit.

[0016] Figure 11 B shows example clamp circuits.

[0017] Figure 12 shows an example single-switch based time-varying voltage profile generation device with a fault power converter.

[0018] Figure 13A shows an example full-bridge time-varying voltage profile generation device including an isolator.

[0019] Figure 13B shows example isolators.

[0020] Figure 14 shows an example time-varying voltage profile generation device with back- to-back insulated gate bipolar transistors.

DETAILED DESCRIPTION

[0021] In various contexts, a power source, such as a power store (e.g., a battery, fuel cell, or other power store), solar cell, wind turbine, chemical process, or other power source, may output power in a state (e.g., voltage, wattage, current, direct current, alternating current, or other characterization metric) that does not match a target output for a system incorporating the power source. Various contexts may have mismatch between multiple power sinks connected in a unified system (e.g., battery chargers, motors, or other power consuming devices). In other words, a system may have heterogeneity resulting from various power nodes (e.g., power sources and/or power sinks) in the system.

[0022] Using batteries as an illustrative example, batteries that may be uniform or otherwise non-diverse (e.g., at the time of manufacture, installation, or other life cycle point) may degrade at different rates, in some cases, including contexts of uniform and/or load balanced usage. Thus, an initially uniform set of batteries may degrade such that the output of the example set differs from the target output of the system. Further, the deviation from the target (or the expected contribution to the target) output by individual batteries in the example set may differ from battery to battery. Diverse degradation may occur at various levels of battery technology, for example different battery packs may degrade differently, further within those packs, modules, and/or individual cells may have diverse degradation. Batteries may refer to any portion of battery technologies and/or other technologies that behavior as a power storage unit. For example, multiple battery packs, modules, cells, chargers, controllers, power converters, or other battery internals connected via virtually any set of electrical interconnects may, in some cases, be referred to as a single “battery". Further, power stores (such as batteries) may in various contexts behave as power sources, power sinks (e.g., while charging), or other power nodes. Solar cell/array power generation may differ as a result of transient and/or spatially variant irradiance profiles, cell degradation, cell obfuscation (e.g., via dust or other detritus), or other non-uniform interference with power generation.

[0023] As an illustrative scenario, second use of retired electric vehicle (EV) battery packs (e.g., as residential power backup or other power backup) may require installation of battery packs that have already undergone degradation as a result of usage. Further, battery packs span a wide range of capacities, ratings, and form factors for a wide array of vehicles. The diversity may increase as technologies for faster charging and newer battery chemistries emerge. This diversity is not only reflected in the second use packs for energy storage, but also in the charging of different vehicles within a station. However, during these periods of rapid change, markets may in part resist some standardization since improvements in battery performance provide benefits to producers able to incorporate new technologies when advances outweigh the benefits of standardization.

[0024] Similar trade-offs exist between standardization and incorporation of new technology with other power nodes.

[0025] In various implementations, systems may implement power converters to convert the power from at power node into the state used at the output port. In various implementations, full power processing (FPP) may include placing a power converter between the power node and the target port to convert the power at the power node to that of the target port. In some cases, a converter may be paired to each node in a group tied to a target port. The converter may process all of the power from the node.

[0026] In some cases, partial power processing (PPP) may be implemented. Although the number of converters may be dependent (e.g., equal or similar to) the number of power nodes, the PPP converters may process less than all of the power at the nodes. Instead, processing may be focused on a portion of the power to adjust the power from the power nodes to an output state. In some cases, PPP may reduce the overall power processed. In some cases, PPP operations may increase efficiency relative to FPP because PPP (even with otherwise identical converters) does not process the full power of the system. Accordingly, per converter inefficiencies are reduced by the relative size of the portion being processes. For example, a FPP system processing 100% with 5% loss will lose 5% of the power of the system. A PPP configuration with the same converters processing 10% of the power, will lose 0.5%. Other efficiencies such as reduced internal heating may be gained.

[0027] For example, differential power processing (DPP) may operate on the portion of the power that differs from the target state. In some cases, the power nodes may differ only on a given range (e.g., X% to Y%, where Y>X). Accordingly, power converter set, each individually capable of handling the maximum deviation of the range (e.g., Y%), may be sufficient to support power conversion. In some cases, the cost of a power converter may scale with the processing capacity of the converter. Accordingly, systems configured to employ PPP and/or DPP may have cost savings advantages over FPP systems. However, some FPP systems may operate where no information about current operation condition I future operational condition of power node is known. For example, DPP and PPP may have operational tolerance ranges where a particular output may be delivered. If a set of power nodes falls outside the range (or for example degrades to the point it is outside the range after installation), the PPP system may fail.

[0028] In some cases, statistical, empirical, and/or theoretical models may provide information of power node condition. For example, a model of battery degradation versus use and/or time may provide a distribution of states for a given second-use battery population. Accordingly, such a model may provide predictive information on a set of batteries drawn from such a population.

[0029] For example, a particular population (or other group) of power nodes may be diverse for one or more reasons such as degradation, model type, or other diversity factors. A diversity model, including models generated from power node characterizations, statistical models, or other models of power node performance, may be used to provide information on the expected characteristics of a power node selected from that particular population. Further, using the diversity model the population can be divided into defined portions. The defined portions may be statistical portions, such as percentile ranges, individual node assignments, characterization based assignments or other groupings. Once divided into portions, the portions may be treated specifically, such that electrical coupling to members of that portion may be specific to the characteristics of that power node portion. Thus, systems using diverse power nodes may anticipate power converter sizing requirements. Accordingly, power converters with lower conversion capacity may be used because the uncertainty if the amount of necessary conversion capacity is reduced.

[0030] Therefore, a system capable of processing a set of power nodes with conditions estimated by a model may allow comparatively robust performance to blind and/or limited characterization implementations, while not requiring detailed characterization of individual power nodes in the set. Further, a system capable of making model-referenced corrections may allow for more uniform construction of power processing systems rather than relying on highly power-node-set-specific interconnects and power converter units.

[0031] In various implementations, a sparse set (e.g., a group, a tier (with a hierarchical relationship with another set of power converters), multiple hierarchical tiers within the set itself, or other configuration) of power converters may be selected to correct from a model- referenced estimates of power node variation for a set of power nodes. The sparse set may include a number of power converters that is dependent on the power node differences as estimated by the model. Thus, in some cases, the number of power converters in the sparse set may be fewer than the number of power nodes serviced by the power converters. As an illustrative example scenario, an example model may estimate that set of nine power nodes (selected by a population of power nodes governed by the model) may be (on-average) interconnected to three power converters for adjustment among the power nodes. In the illustrative example scenario, the three power converters may rebalance outputs/inputs from various ones of the power nodes to ensure a particular power. In some cases, the three power converters may process input over a range to allow for uncertainty associated with choosing a finite number of power converters from the population. The distribution of a finite number of power converters selected from a population may not necessarily align with the distribution of the population as whole.

[0032] In some cases, the power nodes may be connected to the system and operate without individual characterization. The model may be the single node for estimating the condition of the power nodes. The nodes may be connected and assumed to operate within some tolerance of the model estimates.

[0033] In some cases, characterizations such as voltage level outputs, specifications for the power node when new, and/or other information that can be measured without alteration of the power node (or costs rivalling that of the power processing system itself) may be performed. In some cases, the processing system may include characterization elements such as voltage testing capabilities. In some cases, the characterization may be used for initialization, dynamic configuration, and/or other configuration of the system. Characterization may be used to facilitate interconnection of the power nodes that approximates the estimates (e.g., expected values) of power node differences provided by the diversity model.

[0034] In some cases, correction from the diversity model to a uniform model-corrected target power may occur in stages. In various implementations, the sparse set may be implemented as one or more sparse tiers, where power processing may proceed sequentially from tier-to-tier. In some cases, power processing at a sparse converter may occur after power conversion at one or more dense sets of power converters and provide an adjustment that is earlier in series (by current flow) than other power conversion that may be done (e.g., for another power node connected later in a series). Accordingly, tiers may be, in some cases, defined by a localized order from (e.g., from dense to sparse) that may not necessarily align with a device-wide current flow.

[0035] In some cases, between the one or more sparse tiers and the power nodes, the system may include a dense set of power converters (which may include one or more dense tiers). In some cases, dense tiers may be used to correct for uncertainty from deviation of individual power nodes to center (or other target values) values for the particular portions of the power node population. For example, a specific installed group of batteries (power nodes) may have a second-use battery that degraded less than expected for its particular portion of the population and other that has degraded more than expected. In addition, the status of all of these batteries may continue to change over time during this second-use installation. A dense set of power converters may adjust the power from the batteries to more closely match the center values that would be predicted by the model. Then, a sparse set of power converters may correct from the model distribution to the uniform model-corrected target power. In some cases, the dense set may include a number of power converters that is proportional to the total number of power nodes (for example, equal to, one less than, or other number directly dependent on the number of power nodes). [0036] In various implementations, the deviation of individual batteries from the model estimates may be (on average) smaller in magnitude than the correction from the model to the target power. Accordingly, the processing capacity of power converters in the dense set may be smaller than that of those in the sparse set. In some cases, the cost of a power converter may scale with power processing capacity. Hence, in various implementations, a hierarchical system with a dense set of power converters and a sparse set of power converters may have more power converters than a PPP system (as discussed above). The number of power converters in the dense set would be similar to the total number of power converters in the PPP system. However, in some cases, the processing capacity of the individual ones of dense set of converters may be smaller than the individual power converters of the PPP system. For example, the capacity of the individual power converters of the PPP system may be more similar to the power processing capacity of the sparse set of converters. Accordingly, despite having more power converters, the hierarchical system may still be lower cost than a similarly performing PPP system (which is already lower cost than similarly performing FPP system).

[0037] In various implementations where the diversity model is used to subdivide a group of power nodes into portions, the sparse tier may be specifically constructed and used to generate a uniform model-corrected target power, by correcting from center values (or other interim values generated by dense tier correction). The dense tier power converters may be specifically selected to correct variation with a defined portion of the population of power nodes. For example, a device may include multiple different power node connection ports coupled to dense tier power converters. Each connection port may be coupled to one or more dense tier power converters specifically selected to correct for expected variation within a defined portion of the population of power nodes. Additionally, the number of connection ports (e.g., across one or more multiple-port devices) dedicated to each portion of the population may be scaled relative to the relative size of that portion within the population. For example, a portion covering half a population of power nodes may have half of the total number of ports of devices using power nodes from the population configured for correcting for variation within that population. In some cases, the defined portions may be selected to ease such determinations. As an illustrative example, a set of power conversion devices may be designed to have 12 ports, each configurable to support a particular portion of a population of power nodes. The population may then be divided into 12 different portions of at least roughly equal size. In some cases, defined portions may be overlapping (or partially overlapping). Accordingly, a particular power node may be within the definition of two or more different portions. The diversity model may provide an expected range of different supported power flows for a portion. [0038] Referring now to Figure 1 , an example power conversion device (PCD) 100 is shown. The example PCD 100 includes multiple power node connection ports 1 1 1 - 1 19. The each of the connection ports may be configured to support power conversion for a defined portion of the power node group of power nodes.

[0039] The diversity model may provide characteristics of the different portions. For example, the diversity model may provide a center value for expected power flow (such as a mean value, a median value, a selected value for ease of conversion in combination with other center values, or other value). For example, the diversity model may provide an expected range of power flows for the defined portion. In some cases, the defined portion may be defined based on power flow values. However, other characteristics may be used. For example, power node age, power node operating voltage, power node internal resistance (e.g., battery resistance or other internal resistance), power store charge-discharge cycle count, power node current, or other characteristics. In some cases, the populations may be statistically defined (e.g., a percentiles based on expected distributions due to power node age, cycle count, or other factors). Accordingly, membership of a particular power node within any particular portion of group may not be fully discernable. Hence, in some cases, the ports may be configured for different portions and then power nodes may be coupled to particular ports based on a best guess and/or best fit membership assignment. As an illustrative example, a particular PCD may have four ports tuned to different quartiles of total group of power nodes. At the time the PCD is placed into operation, power nodes may be partially characterized, for example, an operating voltage for each power node may be measured. Then, based on the partial characterization, the power nodes may be assigned based on a ranking of the characterized value. For example, in a best fit port assignment scheme the lowest operating voltage measured may be assumed to be best placed in the port of the lowest quartile, including in circumstances where the lowest measured operating voltage may be suggestive of membership in another quartile. In a best guess scheme, the measured characteristic may be used to estimate membership. For example, the lowest measured operating voltage may be assigned to the quartile indicated most strongly by the actual measured voltage value without consideration with regard to ranking in relationship to other power nodes characterized along with that power node at the time of its installation.

[0040] The PCD 100 further includes node interconnects 140 between the multiple power node connection ports 11 1 - 1 19. The node interconnects 140 may be configured to couple the power node connection portions 1 11 - 1 19 in a parallel or series configuration. In some cases, one or more series string of ports may be coupled in parallel to other individual ports. The PCD 100 further includes interconnects 130 between the multiple power node connection ports 1 1 1 - 119 and a sparse set of power converters 141 , 142, 144. The sparse set works to adjust power at different points to ensure a final uniform model-corrected power at the port 150.

[0041] As discussed below, the interconnects may include dynamic switching to support reconfiguration of the connections over time. The switching may allow the power converter - power source connections to be changed after initial setup, for example, as a result of non- uniform degradation among the power sources. In some cases, dynamic reconfiguration may be applied in response to different use conditions. For example, the ports 1 1 1 - 119 may be switched such that they are coupled in series when power flows outward from the ports. For example, this may correspond to coupled batteries discharging during operation. However, the ports 111 - 1 19 may be switched such that they are couple in parallel when power flows inward to the ports. For example, this may correspond to coupled batteries charging.

[0042] The tier interconnects 130 may include a set of dense power converters 131-139 to provide a first stage adjustment (e.g., with partial power processing of the model-deviation power) the power node connection ports 1 11 - 1 19 in accord with the center values provided by the model. In some cases, such adjustment may include differential and/or partial conversion to an interim value that is selected in reference to the center values from the diversity model, but differs from the referenced center values. For example, an interim value may include a value corresponding to multiple center values added together, a difference between two center values, or other target value referencing the center values. In some cases, the interim values may be the center values from the diversity model. The model-deviation power may include the portion of the power that deviates from the center values provided by the diversity model. The dense set of power converters 131-139 may be connected in one or more tiers (which as discussed below are the sparse set 141 , 142, 144 within the hierarchy). The total number of tiers in the power converter hierarchy may include the number of tiers of dense set power 131-139 converters added to the number of tiers of sparse set of power converters.

[0043] The tier interconnects 130 further include passive connections (e.g., parallel, series, capacitive, inductive, power converting, and/or other interconnects) to assist in the adjustment. Accordingly, the tier interconnects 130 may not necessarily connect the power node connection ports one-to-one with dense tier power converters. For example, multiple series connected nodes may be used to estimate a desired operating voltage before connection to a power converter. Accordingly, the power from multiple node connection ports may be processed by a single converter. In some cases, for simplicity of analysis and/or presentation a complex electrical system may be referred to, depicted as, or reduced (via circuit equivalents) to a single node and/or single node connection port. In various implementations, connection ports may be permanently wired to a particular power node. Accordingly, a port may include a power interface for power flow out of and/or into a power node regardless of the permanent or temporary nature of the coupling of the interface.

[0044] In various implementations, the sparse set 141 , 142, 144 may be fed by the interconnects 130 (and the dense set of power converters). The sparse set may provide partial power processing to adjust the power from model-referenced interim values (e.g., which are approximated by the adjustment via the interconnects 130) to ensure the uniform model- corrected target power at the target port 150. In other words, the sparse set of power converters provides partial power processing of the power (e.g., with taps as various points within the PCD) to obtain the power format used by the system being powered by the power sources.

[0045] Figure 2 shows an example parallel PCD 200. In the example parallel PCD 200. The power node connection ports 21 1 - 219 are coupled in parallel to a target port 250 and the various sparse tier converters 251 , 252, 254. The dense tier converters 231 - 238 may be coupled between the power node connection ports 21 1 - 219 and the sparse tier converters 251 , 252, 254 using parallel and/or series connections.

[0046] In various example parallel partial power processing architectures, a virtual tier of power converters 241 - 249 may be used to allow for circuit duality based analysis. The virtual tier of power converters 241 - 249 may allow for the treatment of the power nodes as equal “current sources” rather than “voltage sources” for the purposes of circuit analysis. Thus, a series circuit may be reformed as a parallel circuit with the addition of such power converters. However, rather than providing physical converters to provide this “zero” stage conversion, the contribution of this virtual tier of power converters 241 - 249 may be subsumed into the operation of the dense tier converters 231 - 238. In some implementations, using the circuit duality may facilitate dual mode implementations. Accordingly, a PCD that operates in series in one mode may be converted to a parallel circuit using the virtual tier of power converters 241 - 249 when operating in a second mode. Thus, the adjustment to the operation of the dense tier converters 231 - 238 may be determined based on the virtual power conversion requirements when switching between series and parallel operation dynamically. Thus, in some cases, such virtualization may allow for simplification of dual mode operation.

[0047] The example dynamically switched PCDs may include meter circuity which may perform characterizations at power node connection ports 1 11 - 119 For example, the meter circuitry may characterize voltage, power storage capacity (e.g., via charge-discharge cycle voltage patterns, power flow over a charge-discharge cycle, or other cycle measurements), internal resistance, power flow, current flow, cycle count, power node age, or other power node behavior.

[0048] The switching circuitry may include processing hardware to determine when a switching condition occurs. A switching condition may include a pre-determined condition for which a particular interconnection layout is assigned. For example, switching condition may include one or more thresholds for one or more characterized values. In an illustrative example, a switching condition may include a PCD exceeding a particular charge cycle count, and/or age from a reference point (such as initial installation). A switching condition may include a change in operation mode. For example, switching condition may include a reversal of power flow from the power node connection ports 11 1 - 119 (or other indication of a change from discharging to a charging mode). For example, the switching condition may include a determination that the power node connection ports 1 1 1 - 119 have transitioned from an initial non-diverse state to a diversity state (e.g., a state in which the initial uniform powers nodes currently exhibit different behaviors, such as a degradation state).

[0049] When a switching condition is determined to have occurred, the switching circuitry may switch the interconnects 130, 140 to conform with an interconnect layout consistent with the determined switching condition.

[0050] For example, the switching circuitry 504 may recouple power node connection ports. For example, in a device interconnecting multiple batteries, aged batteries may degrade at different rates. One or more of the power node connection ports may be coupled to power converters sized to handle more significant degradation than others of the power node connection ports. Accordingly, the switching circuitry may recouple to ports to dedicate the particularly sized converters to the batteries that underwent the most significant degradation based on measurements from the meter circuitry. Similarly, the batteries that underwent the least significant degradation may be switched to power converters particularly sized for lower degradation. Initially, the non-diverse state of the batteries may allow for any of the batteries to be equally well served by any of the power node connection ports despite the different sizing of their coupled power converters.

[0051] Figure 3 shows an example time-varying voltage profile generation device (TVPD) 300. The example time-varying voltage profile generation device 300 includes multiple power node stages 31 1-319. Each of the stages 31 1-319 may include one or more power nodes (e.g., such as batteries, solar cells, wind turbines, charging batteries with reverse current flow, and/or other power node types). The power node stages 31 1-319 may be coupled to a tiered power converter structure 340 including power converters grouped into one or more tiers. The tiered power converter structure 340 may distribute power among power nodes within the stages and/or across multiple stages depending on the structure of the tiered power converter structure 340. In other words, each of (or at least some of) the stages may have their own tiered power converter structure and/or one or more tiered power converter structures may interconnect different stages. Multiple nested power converter structures may be used. The tiered power converter structure 340 may include, for example, any of the various tiered power conversion devices discussed above and/or other tiered power converter structures, including single-tier power converter structures. Single-tier power converters may include the functionality of any individual tier of any of the PCDs (e.g., 100, 200) discussed above. Additionally or alternatively, a single-tier power converter structure may combine functionality of multiple stages. For example, a single-tier power converter structure may be dense with regard to converter number but also correct to and for a power converter diversity model. Additionally or alternatively, tiers may be divided in accord with the power distribution function performed. For example, one or more tiers may operate to support DC-to-DC power conversion, e.g., distribution of power load among power sources. For example, one or more tiers may operate to distribute power among different switches, e.g., to support power distribution during switching functions. The distribution of power may be within a signal power node stage (e.g., single-stage) and/or across different power stages of the TVPD (e.g., crossstage). Other power redistribution schemes may be used. After power flow redistribution, outputs associated with individual ones of the stages 311-319 may be selectively output coupled by the switches 320. The switches 320 may include various switching modules, such as single switches, half-bridge modules, full-bridge modules, or other switch types.

[0052] The power nodes may include power nodes of different types, such as batteries, solar cells, electro-chemical power stacks, wind turbines, fuel cells, fuel generators, and/or other power node types.

[0053] In various implementations, the number of concurrent selectively coupled stages may be used to control the magnitude of the output voltage. Changing the number of concurrently coupled stages may be used to vary the magnitude of the output voltage. The polarity of the voltage may be controlled using the switching modules (e.g., for half-bridge and/or full-bridge configurations), an unfolder, and/or polarity selection switches that may be used to selectively couple power nodes in coupling configurations for negative polarity or those in coupling configurations for positive polarity. Various switch types may be used within the modules, for example, transistors, bipolar transistors, field-effect transistors, mechanical switches, and/or other switch types. [0054] The output of the switches 320 may be coupled to various output components 360 such as isolators, clamp circuits, unfolder circuits, and/or other output circuits. The output components 360 may in turn couple to a load (e.g., such as a device, power grid, and/or other system).

[0055] Figure 4 shows example voltage profile generation logic (VPGL) 400. The example VPGL 400 may control the operation of the TVPD 300 and may be implemented on circuitry. The VPGL 400 may obtain a time varying voltage profile (TWP) for generation (402). For example, the TWP may include a target output. For example, a target output may include an alternating current (AC) input for a power grid. In some cases, the AC input may include a voltage profile with a specific phase, amplitude, frequency for a particular periodic function, such as a sinusoidal wave. In some cases, the TWP may be determined via a static switching protocol, a dynamically controlled switching protocol, a programmable input, a profile input, one or more regulatory guidelines/rules or other profile source.

[0056] Once the target output for the TWP is obtained, the VPGL 400 may cause the switches 320 to selectively couple the individual power node stages 311-319 to with timings to generate the TWP (404). As the TWP is generated the VPGL 400 may cause the tiered power converter structure 340 to redistribute power (406) (e.g., among the power nodes via DC-to-DC conversion and/or among the switches to support the TWP generation).

[0057] Figure 5 shows an example single-switch based TVPD 500. The single single-switch based TVPD 500 may use individual switches 502 for each of the switching levels used by the TVPD 500 for generation of voltage levels within a TWP. One or more power nodes 504 may be coupled for each of the switches 502. However, the one or more tiers of the PCD 506 may distribute power among the nodes 504 (e.g., via DC-to-DC power conversion) and/or the switches 502 (e.g., to obtain switching level target outputs). In the example TVPD 500, the switches and power nodes are shown as being coupled in series. However, other configurations may be used. For example, one or more of the power nodes may be coupled in parallel. The nodes individually may include one or more series and/or parallel coupled power sources and/or power sinks. The PCD 506 may use parallel and/or series coupling for implementation of the tiered structure.

[0058] In the example single-switch based TVPD 500 during operation, one switch is on at a time to effect each of the different output voltage levels for TWP generation. The single-switch based TVPD 500 includes a first array 510 of power nodes for one polarity voltage output and a second array of power nodes 520 for the other polarity. The reliance on a single switch may reduce conduction losses by the TVPD 500 during operation. The single switch may receive the entire operating current and voltage of the device and may be rated to handle the entire power output.

[0059] Figure 6 shows an example single-switch based TVPD 600 including an unfolder circuit 650. An unfolder circuit 650 may be paired with a single-switch based TVPD 600 to selectively invert the polarity of the output of the system. In various implementations, the unfolder circuit 650 may allow the single-switch based TVPD 600 to produce two output polarity without reliance on two power node arrays to produce the opposing polarities. Virtually any full-bridge switch may be implemented as an unfolder circuit. During operation, the singleswitch based TVPD 600 may operate with three on switches for each TWP level. One switch 502 may be on within the power node array 610, while two switches 652 may be used within the unfolder circuit. The single switch 502 in the power node array 610 may receive the entire operating current of the device and may be rated to handle that entire current. The two switches within the unfolder circuit may receive 50% (on average) of the total.

[0060] In various implementations, various inverter circuits may be used (e.g., in place of the unfolder circuit 650) to invert the output polarity of the TVPD 600.

[0061] Figure 7 shows an example half-bridge based TVPD 700. In the example half-bridge based TVPD 700. The half-bridge switch modules 702 of the half-bridge based TVPD 700 allows the individual switching stages of the half-bridge based TVPD 700 to selectively contribute to the output of the TVPD 700. Thus, the half-bridge switch modules 702 within a polarity array 710, 720 may be turned on in any order and in any number. The voltage load at each of the half-bridge modules is that contributed by the corresponding stage of the TVPD 700. Accordingly, the stress on the half-bridge switch modules 702 of TVPD 700 may be comparatively less than that on the single switches 502 of TVPD 500 for a given operational output. In some cases, switching modules of the same speed may be cheaper for TVPD 700 than TVPD 500 because lower voltage rating switches may be used.

[0062] Additionally or alternatively, because the half-bridge switch modules 702 may be activated in any order, some implementations may distribute the duty cycle among the different power stages, such that the stages spend a selected amount of time on/off load, rather than a specific stage in the array always being switched on first and switched off last. The distribution may implement various schemes, such as, equal average load distribution, target on load times for individual stages, maximum average time between switching operations (e.g., for specific switches and/or for all switches), or other switching optimization schemes.

[0063] In the example half-bridge based TVPD 700 and similar to the single switch TVPD 500, two polarity power node arrays 710, 720 are used. Two polarity selector switches 712, 722 are used to selectively activate the corresponding array 710, 720. The half-bridge based modules 702 can be activated independently of the arrays 710, 720. Accordingly, the two additional selector switches 712, 722 are used to then select the active polarity array 710, 720. The active selector switch 712, 722 may receive the full output power of the TVPD 700 during operation and may be rated accordingly.

[0064] In some cases, the TWP may be inverted at a lower frequency than that of the sampling rate of the TWP. As an illustrative scenario, a sinusoidal may be sampled at 600 Hz, but be inverted at a rate of 120 Hz. Thus, a cycle of the signal may be 60 Hz while the sample resolution of the overall signal is 600 Hz. Nevertheless, the speed of the selector switches may be five times less than that of the half-bridge switch modules 702. Other sampling and inversion rates may be used.

[0065] Figure 8 shows an example half-bridge based TVPD 800 with an unfolder circuit 850. Similar to the TVPD 600, a half-bridge based TVPD 800 may be implemented with an unfolder circuit 850 (and/or another inverter circuit) to selectively invert the output of the TVPD 800 without reliance on two polarity arrays. Accordingly, a single polarity array 810 may be used in the example half-bridge based TVPD 800 when an unfolder circuit 850 is implemented.

[0066] Figure 9 shows an example full-bridge based TVPD 900. The full-bridge switch modules 902 may be used to selectively activate selectively polarize the output of each switching stage of the example full-bridge based TVPD 900 individually. Accordingly, the stages of the example full-bridge based TVPD 900 may be activated in any order and with any polarity.

[0067] Figure 10 shows example parallel tiered structure based TVPDs 1010, 1020, 1030. Parallel power nodes and PCD arrangements may be used in various implementations using the parallel - series circuit duality. Such parallel/series tiered arrangements 1012, 1022, 1032 may be used with single switch 1010, half-bridge 1020, and 1030 TVPDs. In various implementation, the nested tiered structures 1002 may include nested TVPDs to create selectable voltage outputs for each stage of the TVPDs 1010, 1020, 1030. For example, individual ones of the stages of a bridge-based TVPD 1020, 1030 may include a nested tiers single-switch TVPD capable of time varying output at the stage level. In some cases, the nested tiers may include bridge-based structures within a single-switch TVPD 1010 and/or within a bridge-based TVPD 1020, 1030. When nested within another TVPD at the stage level, a full-bridge structure may also vary its own polarity output. Thus, a single-switch TVPD 1010 or half-bridge TVPD may have selectively polarized output without an unfolder circuit, polarity selector switches, and/or multiple polarity arrays. [0068] Figure 11A shows an example single-switch based TVPD 1 100 including a clamp circuit 1 170. The clamp circuit may be used to hold a particular voltage output for a selected period. The clamp circuit 1 170 may be used to eliminate between-switching dead-times and/or other transient waveforms that may occur as a result of switching action or other TVPD operations. Although shown in a single-switch TVPD 1 100 configuration, the clamp circuit 1 170, the clamp circuit may be used with the half-bridge and full-bridge switching systems. Figure 1 1 B shows alternative example clamp circuit structures 1198, 1 199 which may be implemented.

[0069] Figure 12 shows an example single-switch based TVPD 1200 with a fault power converter 1280. In the example single-switch based TVPD 1200, the fault power converter 1280 may be used to compensate for a fault in one or more of the power stages 1203 of the TVPD 1200. The power node 1204 at the power stage 1203 may have a fault during operation. The fault may cause the power node 1204 to cease providing power when active. Responsive to the cessation of power during its active state, the fault diode 1282 may bypass the power stage 1203 and the fault power converter 1280 may activate to compensate for the cessation. Although not shown, the TVPD 1200 may include multiple fault diodes (e.g., for each power stage). Although not shown, multiple-power-converter and/or tiered structures may be used as the fault power converter. For example, a nested TVPD with a selectable time-varying output may be used to flexibly compensate for various faults of varying degrees (e.g., multiple simultaneous power stage faults).

[0070] Figure 13A shows an example full-bridge TVPD 1300 including an isolator. During operation, the full-bridge switching modules 1302 may implement a set of two switches in the module to “chop” the output of the switching stage (e.g., turn the output on and off at a selected rate greater than the sampling frequency of the TWP). The chopping of the voltage output creates a high frequency component within the signal that may allow the power stage 1303 output to pass through an isolator 1390 for the power stage 1303. The isolators 1390 may prevent backflow of power (e.g., lacking the high frequency component) towards the power nodes thereby preventing reverse-flow system damage. The individual isolators 1390 may be tuned to different high frequency components, to allow for isolation between the power stages. Thus, different types of power stages that may normally interfere with one another, may be used together via the isolation. Because a set of switches the full-bridge modules are used for chopping, an unfolder circuit 1350 may be used. In some cases, one-and-a-half bridge switching modules may be used for selective activation, chopping, and polarity selection. Figure 13B shows various example isolator configurations 1392, 1394, 1396, 1398. In various implementations, a passive isolated rectifier 1392 may be used. In various implementations, an active isolated rectifier 1394 may be used. In various implementations, a passive isolated rectifier with a center tapped winding 1396 may be used. In various implementations, an active isolated rectifier with a center-tapped winding 1398 may be used.

[0071] Figure 14 shows an example TVPD 1400 with back-to-back insulated gate bipolar transistors (IGBTs) 1460. The back-to-back IGBTs 1460 may be used as switching modules (single-switch modules as shown) to selectively activate the various power stages 1420 supported by the PCD 1410. The example TVPD includes a buck converter 1480 for fault tolerance, a clamp circuit 1470 for transient mitigation, and an unfolder circuit 1450 for polarity selection.

[0072] Various example implementations have been included for illustration. Other implementations are possible. Table 1 shows various examples.

[0073] The present disclosure has been described with reference to specific examples that are intended to be illustrative only and not to be limiting of the disclosure. Changes, additions and/or deletions may be made to the examples without departing from the spirit and scope of the disclosure.

[0074] The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

Claims

What is Claimed is:

1. A device including: multiple power nodes; one or more tiers of power converters configured to control power flow distribution among the multiple power nodes to generate individual target voltage outputs for each of the multiple power nodes, the one or more tiers of power converters including: a dense tier including a first number power converters proportional to a total number of the multiple power nodes and configured to perform less than full power processing on at least one of the power nodes; and a time-varying voltage profile generator including multiple switches configured to selectively apply the individual target voltage outputs of the multiple power nodes to generate a predetermined time-varying voltage profile.

2. The device of claim 1 , where the predetermined time-varying voltage profile includes stepwise generation of a target voltage profile via additive and/or subtractive application of the individual target voltage outputs.

3. The device of claim 1 , where a power flow is controlled using a cross-stage power converter structure configured to distribute power flow from at least some of the multiple power nodes.

4. The device of claim 3, where the cross-stage power converter structure couples the at least some of the multiple power nodes in parallel and/or series.

5. The device of claim 1 , where the one or more tiers of power converters include a DC conversion tier configured to perform DC-to-DC power conversion and/or a switching tier configured to perform switching-level power conversion to support time-varying voltage profile generation.

6. The device of claim 1 , further including an unfolder circuit is used to selectively invert the time-varying voltage profile.

7. The device of claim 1 , where the multiple switches include a transistor, a bipolar transistor, a field-effect transistor, and/or a mechanical switch.

8. The device of claim 1 , where the multiple switches include one or more back-to-back insulated gate bipolar transistors (IGBT).

9. The device of claim 1 , where the multiple switches include a half-bridge switching module and/or a full-bridge switching module.

10. The device of claim 1 , where the time-varying voltage profile generator is configured to selectively switch individual ones of the multiple power nodes in a defined order to generate the time-varying voltage profile.

11 . The device of claim 1 , where the time-varying voltage profile is characterized by an output application frequency and an isolation frequency, the isolation frequency selected to pass the time-varying voltage profile through an isolator, the isolation frequency being greater than the output application frequency.

12. A device including: multiple power nodes grouped into multiple stages; one or more tiers of power converters configured to control power flow distribution among the multiple power nodes to control individual target voltage outputs for each of the multiple stages, the one or more tiers of power converters including: a dense tier including a first number power converters proportional to a total number of the multiple power nodes and configured to perform less than full power processing on at least one of the power nodes; and a time-varying voltage profile generator including multiple switches configured to selectively apply the individual target voltage outputs to generate a predetermined time-varying voltage profile.

13. The device of claim 12, where power flow is controlled using a single-stage power converter structure configured to distribute power flow from power converters within a single stage of the multiple stages, and/or a cross-stage power converter structure configured to distribute power flow from power nodes among different stages of the multiple.

14. The device of claim 13, where at least one of the power converter structures couples at least some power nodes in parallel.

15. The device of claim 13, where at least one of the power converter structures couples at least some power nodes in series.

16. The device of claim 13, where: the multiple power nodes includes power nodes of multiple power source types; and at least one of the multiple tier power converter structures distributes power among at least some power nodes with different power source types.

17. A device including: multiple power nodes grouped into multiple stages; for at least some of the individual ones of the multiple stages: multiple tiers of power converters configured to control power flow distribution among the multiple power nodes to control the individual target voltage output for the stage, the multiple tiers of power converters including: a dense tier including a first number power converters proportional to a total number of the multiple power nodes; and a sparse tier including at least one power converter with a power converter rating greater than that of any power converter in the dense tier; and a time-varying voltage profile generator including multiple switches configured to selectively apply individual target voltage outputs for the multiple stages to generate a predetermined time-varying voltage profile.

18. The device of claim 17, where the multiple tiers of power converters include at least one fault converter configured to maintain the power flow throughout a failure event associated with one or more of the multiple power nodes.

19. The device of claim 18, where the failure event includes an acute cessation of power flow from the one or more of the multiple power sources.

20. The device of claim 17, further including an isolator is used between the multiple switches and the load that receives the predetermined time-varying voltage profile, where: the isolator includes an active rectifier, a passive rectifier, and/or a center tapped rectifier.