Reconfigurable battery management system

Abstract

The invention relates to a battery control system. The battery control system includes a circuit module having a pair of output terminals. The circuit module has a plurality of cell modules selectively connectable with the output terminal in a series configuration to provide a target output voltage on the output terminal, each cell module including at least one battery cell, a switching circuit configured to selectively operate in two or more states. The states include: a state in which at least one cell is bypassed from the series string; and a state in which the at least one battery cell is connected in series with the series string. The controller is configured to provide a target output voltage based on selective control of an operating state of each switching circuit of each cell.

Description

Technical Field

[0001] This invention generally relates to controlling an energy storage module, which typically includes battery cells in an energy storage system, and specifically relates to controlling the energy storage module to improve voltage output generation and efficiency. Background Technology

[0002] Energy storage systems used in applications such as all-electric vehicles, hybrid electric vehicles, and stationary energy storage in grid-connected or off-grid applications often include an arrangement of multiple energy storage cell units.

[0003] Each battery cell is limited by its functional mechanism and design to provide an output voltage within a certain range, depending on its state of charge and operating conditions. Each battery cell is also limited by its functional mechanism and design to provide a certain maximum charge storage capacity, depending on operating conditions. Connecting battery cells in series increases the maximum achievable output voltage, thus reducing the amount of current required to supply a given power output. This increases system efficiency because ohmic losses increase with the amount of current. Connecting battery cells in parallel increases the maximum achievable storage capacity for a given battery cell capacity and storage system output voltage level.

[0004] Individual battery cells inevitably exhibit some differences in charge storage capacity, internal resistance, and other performance-related factors. Even before entering their operational life, battery cells inevitably have variations due to manufacturing tolerances, which allow for certain variations in the manufacturing process, even with state-of-the-art existing technology manufacturing processes. Throughout their operational life, variations in battery cell performance degradation conditions or profiles further contribute to these differences. In applications where used battery cells are recycled for reuse, significant performance differences can be associated with battery cells, especially if the battery cells have been exposed to different usage profiles. Utilizing battery cells with different specifications can also contribute to battery cell differences.

[0005] Publications including US10573935B2 present a novel method for balancing the performance of multiple energy storage cell units in an energy storage system. This method involves balancing the battery by allowing each individual cell unit to be included or bypassed when connected in series via bypass / included MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) switches during battery operation. The publication also reports a novel layout with unique advantages. Publications US20210265710A1 and US11264812B2 further improve upon US10573935B2 by adding more layouts that allow for changes in the polarity of the energy storage system without requiring an inverter or H-bridge. This allows the energy storage system to act as a multilevel inverter without requiring an H-bridge or converter or inverter.

[0006] These systems are used in multilevel inverters or reconfigurable battery systems (or reconfigurable energy storage systems), which typically contain a large number of battery modules or cells (nodes), and even more switches to control these nodes. The cells are connected in series to produce the desired output voltage. The control scheme must be able to select which nodes to connect in series and which to bypass based on load requirements and balancing requirements.

[0007] However, such multi-cell systems present persistent problems, making it crucial to manage the load applied to any single cell and its environmental conditions for the lifespan of the cells within the system. Therefore, the object of this invention is to improve upon the aforementioned problems of the prior art, or at least to provide the public with a useful alternative. Other objectives will be apparent to those skilled in the art. Summary of the Invention

[0008] On one hand, the present invention relates to a battery control system, the battery control system comprising: a circuit module including a pair of output terminals configured to provide a target output voltage, the module including: a string of cell modules, each cell module including: a first terminal and a second terminal, at least one cell, a switching circuit configured to: connect the first terminal to the second terminal thereby bypassing at least one cell, or connect at least one cell between the first terminal and the second terminal; and a controller configured to control the switching of one or more cell modules to target the output voltage of the circuit module.

[0009] On one hand, the present invention relates to a battery control system, the battery control system comprising: a circuit module including a pair of output terminals, the circuit module including: a plurality of cell modules, the plurality of cell modules being selectively connected to the output terminals in a series configuration to provide a target output voltage at the output terminals, each cell module including: at least one battery cell; a switching circuit configured to selectively operate in two or more states, the states including: a state in which at least one cell is bypassed from the series string; and a state in which at least one cell is connected in series with the series string; and a controller configured to provide the target output voltage based on selective control of the operating state of each switching circuit for each cell.

[0010] In some embodiments, the controller is configured to control the switching circuit of one or more battery cell modules to meet a target circuit module output voltage by a combination of: connecting one or more battery cell modules in series with an output terminal; and modulating the state of the switching circuit of at least one battery cell module relative to the state of the series connection of one or more battery cell modules, such that the target voltage is substantially provided at the output terminal of the circuit module.

[0011] In some embodiments, the controller is configured to: determine a set of battery cell modules for series connection to meet a target output voltage within a predetermined time increment; and control a switching circuit for one or more battery cell modules, comprising a combination of: connecting one or more battery cell modules in series with an output terminal, and modulating the switching state of at least one battery cell module within a predetermined time increment such that an output voltage is substantially provided at the output terminal of the circuit module.

[0012] In some embodiments, the controller is configured to: determine the output voltage of a target circuit module, and the modulation duty cycle of a modulation of the switching state of at least one cell module based on the output voltage of the target circuit module.

[0013] In some embodiments, the controller is configured to control the switching of one or more battery cell modules to meet the target circuit module output voltage by a combination of connecting one or more battery cell modules in series with an output terminal and modulating the switching state of at least one battery cell module such that the target voltage is substantially met at the circuit module output terminal.

[0014] In some embodiments, the controller is configured to: determine a set of battery cell modules for series connection to meet a target output voltage within a predetermined time increment; control the switching of the set of battery cell modules, which includes a combination of: connecting one or more battery cell modules in series with an output terminal; and modulating the switching state of at least one battery cell module within a predetermined time increment such that the output voltage is substantially targeted at the output terminal of the circuit module.

[0015] In some embodiments, the voltage target is defined by the time-varying amplitude and phase, and the controller is configured to control the series connection of one or more cell modules at predetermined time intervals and to control the modulation of the switching state over time based on the time-varying amplitude and phase.

[0016] In some embodiments, the controller is further configured to determine cell data based on at least one cell of each cell in each cell module; and to determine a ranking of each cell module based on the determined cell data, the cell data including one or more of the following: voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in a series arrangement, health status, charging current capability, and discharging current capability.

[0017] In some embodiments, the ranking is determined based on identifying which cell modules contribute to the output voltage; and wherein the ranking is determined by comparing with other contributing cell modules.

[0018] In some embodiments, the controller is further configured to determine cell data parameters based on at least one cell of each cell module, and to determine a ranking of each cell module based on a weighted combination of two or more determined cell data parameters, the cell data parameters including one or more of the following: voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in a series arrangement, and health status.

[0019] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module; and control the modulation duty cycle of the switching state of at least one cell module to satisfy the output voltage of the target circuit module.

[0020] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module; and control the modulation duty cycle of the switching state of the cell module based on the determined ranking to satisfy the output voltage of the target circuit module.

[0021] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, and based on the determined ranking of each cell module: preferentially assign higher modulation duty cycles of the switching state to those cell modules with higher rankings and / or preferentially assign lower modulation duty cycles of the switching state to those cell modules with lower rankings.

[0022] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module; and control the modulation duty cycle of the switching states of two or more cell modules to meet the target voltage.

[0023] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, determine a weighting factor based on the determined ranking, and control the modulation duty cycle of the switching state of each ranked cell module based on the weighting factor, wherein the weighting factor assigns a modulation duty cycle priority to each cell module.

[0024] In some embodiments, the weighting factor defines a uniform distribution of cell modules across the ranking.

[0025] In some embodiments, the weighting factor defines a nonlinear distribution of cell modules across the rank.

[0026] In some embodiments, the system includes a plurality of cell modules, and the controller is configured to: determine a target voltage for cell module balance, and identify one or more cell modules having a voltage higher than the target voltage for cell module balance, and based on the identified one or more cell modules: preferentially allocate higher modulation duty cycles of switching states to those cell modules with higher voltages and / or preferentially allocate lower modulation duty cycles of switching states to the remaining / unidentified cell modules.

[0027] In some embodiments, the controller is configured to: determine the difference between the sum of one or more battery cell modules and a target output voltage; and then, for a switching circuit of at least one battery cell module, control the modulation duty cycle based on the determined voltage difference.

[0028] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, determine the output voltage, determine the difference between the output voltage and the target voltage, and then, based on the difference: adjust a weighting factor for assigning modulation duty cycle priority to each cell module based on the determined ranking, and control the modulation duty cycle of the switching state of each ranked cell module based on the weighting factor.

[0029] In some embodiments, the controller is further configured to, for each modulated cell: determine the degree of difference between the current cell module ranking and the new cell module ranking; and adjust the modulation duty cycle of the switching state of each ranked cell module based on the degree of difference.

[0030] In some embodiments, the controller is further configured to: for each modulated cell: determine one or more cell parameters; and adjust the modulation duty cycle of the switching state of each ranked cell module based on the determined one or more cell parameters, the cell parameters including voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in a series arrangement, health status of each cell module, charging current capability, and discharging current capability.

[0031] In some embodiments, the modulation duty cycle for adjusting the switching state is further based on the scaler multiplier.

[0032] In some embodiments, the modulation duty cycle for adjusting the switching state depends on the ranking of each cell module.

[0033] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, map a weighting factor to the modulation duty cycle priority of each cell module based on the determined ranking, and control the modulation duty cycle and / or frequency of the switching state of each ranked cell module based on the weighting factor.

[0034] In some embodiments, the controller is further configured to measure the voltage at the output terminal and adjust one or more modulation parameters for any one or more cell modules based on the measured voltage.

[0035] In some embodiments, the controller is further configured to: measure the voltage output from the cell module, and adjust one or more modulation parameters for any one or more cell modules based on the measured cell module output voltage.

[0036] In some embodiments, the switching circuit includes a plurality of switches having a set of switching states, the switching states including: a first state in which the switch is configured to bypass at least one cell; or a second state in which the switch is configured to connect at least one cell in series between a first terminal and a second terminal.

[0037] In some embodiments, the system includes two or more cell processors, each cell processor being configured to: determine cell data for one or more cells under the control of each cell processor; transmit the determined cell data to one or more other cell processors, wherein at least one cell processor is configured to determine a ranking of each cell based on the received and determined cell data, and transmit the ranking to one or more other cell processors.

[0038] In some embodiments, the system includes two or more cell processors, each cell processor being configured to: determine cell data of one or more cells under the control of each cell processor; transmit the determined cell data to one or more other cell processors; and wherein each cell processor is configured to determine a ranking of each cell based on the received and determined cell data; and each cell processor is configured to operate a corresponding switching circuit based on the determined ranking.

[0039] In some embodiments, the controller further includes: one or more cell processors and a central processing unit, wherein the one or more cell processors are operatively configured to control the switching state of one or more cell modules; wherein the central processing unit and the one or more cell processors are configured to communicate via a first communication channel.

[0040] In some embodiments, the first communication channel includes a channel suitable for transmitting synchronization signals.

[0041] In some embodiments, the first communication channel is a dedicated synchronization channel. The communication channel between the central processing unit and the cell processor includes an update frequency lower than the modulation base frequency.

[0042] In some embodiments, each of the one or more cell processors is configured to communicate with one or more other cell processors via a second communication channel.

[0043] In some embodiments, one or more cell processors are configured to control the modulation of the switching circuit at a rate higher than the communication rate of the communication channel.

[0044] In some embodiments, the central processing unit is configured to transmit a target voltage to one or more cell processors, and in response, each cell processor is configured to control the state and / or modulation of one or more of its cell modules.

[0045] In some embodiments, the central processing unit is configured to update the target voltage at a first frequency and to modulate the base frequency at least twice the time increment.

[0046] In some embodiments, the central processing unit is configured to send a synchronization signal operable to control the timing of the switching circuit and thereby target a new output voltage, and one or more cell processors are configured to control the switching state of the switching circuit upon receiving the synchronization signal.

[0047] In some embodiments, the system further includes a low-pass filter connected between the cell module string and the output terminal.

[0048] In some embodiments, a predetermined time increment represents the interval at which a target output voltage (or data indicating that target output voltage) is updated. The target output voltage is an ideal output voltage based on an analog time-varying voltage (such as a power supply voltage waveform of approximately 110 or 240 V). This time increment typically has a certain level of tolerance before it deviates too far from a voltage that might match the power supply sinusoidal waveform. This tolerance can be relative to a time interval before which a cell module is added to or removed from a series of cell strings, and can be relative to the voltage level itself. The tolerance can be expressed as voltage, time, or a percentage difference between voltage and time. In some embodiments, the predetermined time increment represents the interval at which a ranking determination is made. In some embodiments, the modulation duty cycle represents the cell contribution duty cycle to the target output voltage based on the cell ranking.

[0049] In some embodiments, the system is a reconfigurable battery system. In some embodiments, the modulation base frequency is at least 1.25, 1.5, or 2 times faster than the time increment. In some embodiments, the modulation includes PWM or PDM. In some embodiments, the voltage target includes a direct current (DC) voltage reference. In some embodiments, the voltage target includes an alternating current (AC) voltage reference. In some embodiments, the voltage target includes a progressive approximation of an AC sinusoidal voltage waveform reference. In some embodiments, the voltage target includes a time-varying DC voltage. In some embodiments, the voltage target includes a waveform that is substantially 50 Hz or 60 Hz.

[0050] In another aspect, the present invention relates to an electric vehicle comprising a system according to any of the foregoing statements, the vehicle comprising: an electric motor controller configured to determine electric motor demand data; wherein the controller is configured to determine the output voltage of a circuit module based on the demand data.

[0051] In another aspect, the present invention relates to an electric vehicle charging system comprising a system according to any of the foregoing statements, the charging system comprising: one or more charger connection points, each configured to be connected to an electric vehicle; a charging controller configured to receive a signal containing charging request data of an electric vehicle connected to one of the charger connection points; wherein the controller is configured to determine a circuit module output voltage based on the charging request data.

[0052] In some embodiments, the invention relates to a combination of any one or more of the foregoing statements and any one or more of the other statements. Other aspects of the invention will become apparent from the following description, which is given by way of example only and with reference to the accompanying drawings.

[0053] If applicable, the entire disclosure of all applications, patents, and publications cited above and below is hereby incorporated by reference. The invention may also be broadly defined to include portions, elements, and features individually or collectively mentioned or indicated in the specification of this application, as well as any or all combinations of any two or more of said portions, elements, or features, and if a particular whole mentioned herein has a known equivalent in the field of this invention, such known equivalent is considered to be incorporated herein as if presented separately.

[0054] Many variations in the construction of this invention, as well as a wide range of different embodiments and applications, will become apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. The disclosure and description herein are illustrative only and are not intended to be limiting in any way.

[0055] The term "and / or" as used in the specification and claims means "and" or "or," or both. The term "comprising" as used in this specification and claims means "consisting of at least partially...". When interpreting statements in this specification and claims that include this term, the feature beginning with that term in each statement must be present, but other features may also be present. Related terms such as "comprise" and "comprised" will be interpreted in the same manner.

[0056] As used herein, the singular forms “an,” “a,” and “the” are intended to include the plural forms as well, unless otherwise expressly stated. It will be further understood that when the terms “comprising,” “including,” “encompassing,” and / or “covering” are used in this specification, they specify the presence of the stated feature, integral, step, operation, element, and / or component, but do not preclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. It will be understood that when an element is referred to as “connected” or “coupled” to another element, it may be directly connected to or coupled to the other element, or there may be intermediate elements present. Attached Figure Description

[0057] The invention can be better understood by referring to the following accompanying drawings. The elements in the drawings are not necessarily proportional to each other, but the emphasis is on clearly illustrating the principles of the invention. Furthermore, throughout the views, the same reference numerals refer to corresponding parts.

[0058] Figure 1 An exemplary control structure for an energy storage system, typically a multilevel inverter or a reconfigurable battery system, is shown.

[0059] Figure 2A and Figure 2B An exemplary battery system is shown, which includes a plurality of battery cell modules, a central controller for controlling the operation of the battery cell modules, and an output module for measuring and verifying the output of the battery cell module 102 and / or processing the output to provide a desired output voltage profile.

[0060] Figure 3 shows a flowchart of the steps performed by a controller that performs modulation control and series connection control of the switching circuit based on the cell ranking determined in the reconfigurable battery system.

[0061] Figure 4 A table is shown that outlines an exemplary duty cycle difference profile based on AC time-varying waveforms.

[0062] Figure 5 / I shows an overview of step B2 of the controller.

[0063] Figure 6 An example of an ideal AC waveform is shown, where the 9V voltage is targeted based on a simplified 12V peak.

[0064] Figure 7 The contributions of the five cells to the AC waveform are shown, with cell one contributing the longest duration and cell five contributing the shortest duration.

[0065] Figure 8A and Figure 8BA table showing overview information is provided, which includes different DCD profile differences. These different DCD profile differences can be used to control the use of the cells over time or to control the use of the cells so that some cells are used more than others.

[0066] Figure 9 illustrates an alternative embodiment in which the cell used is determined solely by DCD.

[0067] Figures 10A-10C The cell contribution profiles are shown, including linear, less aggressive nonlinear, and more aggressive nonlinear profiles, respectively.

[0068] Figure 11 An example of a more aggressive balance profile (and therefore including more cells) is shown, which can result in a better fit to the ideal AC sine waveform with reduced harmonics.

[0069] Figure 12 An example of a linear DCD and an example of a nonlinear DCD are shown.

[0070] Figure 13 An exemplary overview of the controller implementation based on adaptive DCD / BWF is shown.

[0071] Figure 14 An example of how such an adaptive DCD would look over time is shown.

[0072] Figure 15 A and Figure 15 B shows an example based on PWM modulation.

[0073] Figure 15 C and Figure 15 D shows an example of PDM-based modulation.

[0074] Figure 16 A table comparing the differences in cell contributions is shown.

[0075] Figure 17 An example of a ranking-based rounded PDM contribution is shown in the table.

[0076] Figure 18 A- Figure 18 D illustrates an example of modulation based on PDM and PWM compared to existing techniques that do not incorporate modulation.

[0077] Figure 19 A- Figure 19 D demonstrates the advantages of PWM-based modulation compared to PDM-based modulation in this embodiment.

[0078] Figure 20 A- Figure 20D demonstrates the advantages of PWM-based modulation compared to PDM-based modulation in this embodiment. Detailed Implementation

[0079] This document describes exemplary methods, devices, components, and systems. It should be understood that the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or feature described herein as "exemplary" or "illustrative" is not necessarily to be construed as superior to or better than other embodiments or features. More generally, the embodiments described herein are not intended to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods can be arranged and combined into a wide variety of different configurations, all of which are contemplated herein.

[0080] In this specification, the terms "energy storage module," "battery cell unit," "cell unit," or "cell module" are generally intended to refer to a module capable of storing electrical charge, and may refer to a single battery cell or a block of cells connected in parallel, or a combination of multiple single battery cells or a block of cells connected in parallel, or cells connected in series and / or parallel. When using the terms battery cell, cell, or cell unit, the terms battery module, module, cell module, or module unit are equally applicable, wherein a module may contain one or more cells connected in series and / or parallel.

[0081] In this specification, the term "energy storage module" may also refer to a block of cells connected in parallel and / or in series, and further includes circuit components, such as fuses, resistors, passively controlled diodes, capacitors, or inductors, connected in series and / or in parallel with individual cells. The terms "energy storage unit," "storage unit," "battery cell unit," or "cell unit" may also refer to non-battery energy storage elements, such as fuel cells and supercapacitors.

[0082] In some embodiments, the energy storage module may be designed to include one or more energy storage units capable of achieving a charging capacity of at least 10Ah, 20Ah, 40Ah, 60Ah, 100Ah, 200Ah, or 400Ah ampere-hours. In some embodiments, the plurality of energy storage units may include a first energy storage unit and a second energy storage unit, wherein the first energy storage unit has a charging capacity substantially greater than that of the second energy storage unit.

[0083] The embodiments of the invention discussed in this specification relate to a battery control system including a circuit module comprising a pair of output terminals configured to provide a target output voltage. The module includes a string of cell modules and may be referred to as a reconfigurable battery system. Such cell modules typically each include a first terminal and a second terminal, at least one cell, and a switching circuit configured to connect the first terminal to the second terminal to bypass at least one cell, or to connect at least one cell between the first and second terminals. Thus, the cell module can contain any number of cells connected in series, in parallel, or a combination of series and parallel, with the switching circuit controlling the connection of any one of these cells to a cell terminal. For example, in a reconfigurable battery system, it is common for the switching circuit to control the connection of these cells to terminals, or to bypass these cells for the terminals to be connected. Other cell configurations are possible, such as switching circuit configurations that reverse the polarity of cells within a cell module. Polarity control can be provided, for example, by an H-bridge or a 2n+2 reverse H-bridge circuit topology. The controller is configured to control the switching of one or more cell modules to target the output voltage of the circuit module.

[0084] As used herein, the term "controller" is most commonly used to describe the functionality of one or more processing devices, such as microprocessors, but may also include other computing devices or discrete logic circuitry. The term "controller" also includes combinations of multiple processing devices. A controller is typically characterized by output pins that are operatively connected to a switching device to control the state of that switching device. For example, pins of a microprocessor may be connected to the gate of a MOSFET switching device. The controller provides the system's control functions (such as determining a target voltage) and the output signals required to operate the switching circuitry of one or more cell modules to generate the target output voltage.

[0085] The target voltage will be determined based on the system's output voltage requirements. For example, in some embodiments, the system provides a power supply output voltage, which may be a sinusoidal 110 to 240V signal at 50 to 60 Hz. Other examples include DC voltage applications, such as those found in electric vehicles (EVs), EV charging equipment, or other more general DC applications. Accordingly, the target output voltage can be time-varying or time-static. Reconfigurable battery systems are most commonly found with lithium-based cells, and therefore cell voltages typically operate between 2.5V and 4.2V per cell. The cell voltage range means that the output voltage can typically only be stepped based on the cell voltage, i.e., a step of 2.5-4.2V, depending on the voltage of the cell connected at any given time. Other battery technologies or voltage source technologies may specify other voltage steps. Embodiments of the invention relate to improving this step control by including modulation of the switching states of any one or more cell modules, such that much smaller output voltage steps can typically be achieved when combined with filters. Other advantages are also possible, such as time-varying control of the load applied to the cells. Load application can be based on, for example, the determination of cell performance.

[0086] Accordingly, in some embodiments, the controller is configured to control the switching of one or more cell modules to meet a target circuit module output voltage by a combination of connecting one or more cell modules in series with an output terminal and modulating the switching state of at least one cell module such that the target voltage is substantially met at the circuit module output terminal. In this way, at least one cell can contribute a portion of its total cell voltage to the total output voltage of the series combination of cells. For example, a modulation duty cycle applied by the controller will allow control over the voltage contribution of one or more modulated cells.

[0087] In some embodiments, the controller is configured to: determine a set of battery cell modules for series connection to meet a target output voltage within a predetermined time increment; control the switching of the set of battery cell modules; the control comprising a combination of: connecting one or more control modules in series with an output terminal; and modulating the switching state of at least one battery cell module within the predetermined time increment such that the output voltage is substantially targeted at the output terminal of the circuit module. The predetermined time increment is typically determined based on the type of voltage waveform the system is intended to provide. For AC power supply voltage generation, the time increment is typically based on the determination of the target output voltage over the increment period. For example, with a peak AC power supply voltage of 240V, the controller is configured to determine how many battery cells need to be connected in series to meet the target. For example, if all cells are at 4V, then 240 / 4 = 60 cells are connected in series at the peak amplitude of the waveform. The number of cells connected in series will be determined by the voltage of these cells and the voltage of the waveform at any point in time. Therefore, the controller is configured to determine the voltage for the cells that may be connected to the output terminal.

[0088] Therefore, the voltage target is defined by the time-varying amplitude and phase, and the controller is configured to control the series connection of one or more cell modules at predetermined time intervals and to control the modulation of the switching state over time based on the time-varying amplitude and phase. The predetermined interval can be determined by a step of the available cell voltage compared to the desired voltage under the phase increment of the waveform.

[0089] In some embodiments, the controller is further configured to determine cell data based on at least one cell of each cell module; and to determine a ranking of each cell module based on the determined cell data, which includes one or more of the following: voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in a series arrangement, health status, charging current capability, and discharging current capability. As mentioned above, the ability to modulate a cell allows the cell to be controlled to be connected to the load for a shorter time than an unmodulated cell. Therefore, unloading some cells is more advantageous than unloading others. The cell data is used to inform which cells will be advantageously unloaded relative to others. Simple examples include cases where one cell is hotter or has less voltage compared to another cell. When the system has many cells, the cell data of those cells allows for ranking some cells and thus prioritizing their loading over others.

[0090] In some embodiments, ranking is determined based on identifying which cell modules contribute to the output voltage; and wherein the ranking is determined by comparison with other contributing cell modules. When cells are connected to a load, their cell data will often change over time. For example, heat resistance or internal resistance will cause cell characteristics to change over time. Therefore, it is advantageous to determine cell data based on those cells connected to the load (that contribute to the output voltage). Ranking information can be based on more accurate or reliable cell data.

[0091] In some embodiments, cell data points are combined to determine the ranking of a cell relative to other cells. This combination can be based on different methods, including which cell data takes precedence over other cell data. For example, cell temperature is typically more important than other cell data points for cell ranking determination. Thus, in some embodiments, the controller is also configured to determine cell data parameters based on at least one cell for each cell in each cell module, and to determine the ranking of each cell module based on a weighted combination of two or more determined cell data parameters, including one or more of the following: voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in a series arrangement, and health status.

[0092] In some embodiments, the controller is further configured to: determine the output voltage of a target circuit module; and control the modulation duty cycle of the switching state of at least one cell module to satisfy the output voltage of the target circuit module. This means that more than one cell can be modulated in a series of cell strings. In this way, the contribution of multiple cells can be controlled based on the modulation resolution. The modulation resolution can be determined based on processor operating speed, control loop speed, communication speed, and whether switching losses within the switching device need to be mitigated.

[0093] In some embodiments, the controller is further configured to: determine the output voltage of a target circuit module; and control the modulation duty cycle of the switching states of the cell modules based on the determined ranking to satisfy the output voltage of the target circuit module. In the case of a number of cells in a series configuration, the ranking of each cell can determine its contribution to the output voltage, and thus determine the modulation duty cycle.

[0094] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, and, based on the determined ranking of each cell module, preferentially allocate higher modulation duty cycles of the switching state to those cell modules with higher rankings and / or preferentially allocate lower modulation duty cycles of the switching state to those cell modules with lower rankings. In this way, the preferred cells can have different applied duty cycles compared to the selection of lower-ranked cells. Prioritization may further include a nonlinear contribution distribution based on the modulation duty cycle, such that higher-ranked cells are disproportionately loaded compared to lower-ranked cells.

[0095] In some embodiments, the controller is further configured to: determine the output voltage of the target circuit module, determine a weighting factor for prioritizing the modulation duty cycle for each cell module based on the determined ranking, and control the modulation duty cycle of the switching state of each ranked cell module based on the weighting factor. The weighting factor is a factor representing a disproportionate level that can be extended across modulated cells. The weighting factor typically represents a variable in a mathematical representation of the contribution distribution across multiple cells. The variable can be easily changed by the controller based on ongoing cell data measurements.

[0096] In some embodiments, the controller is configured to balance the voltage of multiple cells in a series of cells by determining a cell module balance target voltage, and to identify one or more cell modules with voltages higher than the cell module balance target voltage, and based on the identified one or more cell modules: preferentially assigning higher modulation duty cycles of the switching state to those cell modules with higher voltages and / or preferentially assigning lower modulation duty cycles of the switching state to the remaining / unidentified cell modules. In this way, higher priority cells are loaded more than lower priority cells, allowing their capacity to be used at a higher rate. Control of the duty cycle of each cell allows the cell balance target voltage to converge. Therefore, in some embodiments, the controller is configured to measure the individual cell voltages and adjust the applied modulation duty cycle to converge these cell voltages to the cell balance target. The balance target may evolve over time, for example, as a group of cells are collectively discharged.

[0097] In some embodiments, the controller is configured to implement a feedback loop to measure the output voltage of the circuit, and any difference between the output voltage and a target voltage to control changes in the modulation duty cycle applied to one or more cells. Accordingly, the controller is further configured to determine the output voltage of a target circuit module, determine the output voltage, determine the difference between the output voltage and the target voltage, and then, based on the difference, adjust a weighting factor that assigns a priority to the modulation duty cycle of each cell module based on the determined ranking, and control the modulation duty cycle of the switching state of each ranked cell module based on the weighting factor. The controller can measure the output voltage of the circuit and adjust the modulation duty cycle, or the output voltage from one or more individual cells, or a combination of these measurements.

[0098] When the controller is distributed and includes multiple processors, the modulation of the switching circuitry and therefore the cell voltage contribution to the total output voltage are most advantageous. In a distributed controller system, some processors can operate at higher speeds than others. A specific system has a master or central processing unit that controls the synchronization of cell switching and cell-level processors that control the switching circuitry of one or more cell modules. Typically, the central processing unit is bandwidth-limited and cannot directly control the modulation of the cell modules without overloading the processor and causing problems related to the synchronization of the cell switching function. Therefore, in some embodiments, the system includes two or more cell processors configured to: determine cell data for one or more cells under the control of each cell processor; transmit the determined cell data to one or more other cell processors, wherein at least one cell processor is configured to determine a ranking of each cell based on the received and determined cell data, and transmit the ranking to one or more other cell processors. In some embodiments, the system includes two or more cell processors, each configured to: determine cell data for one or more cells under the control of each cell processor; transmit the determined cell data to one or more other cell processors; wherein each cell processor is configured to determine a ranking of each cell based on the received and determined cell data; and each cell processor is configured to operate a corresponding switching circuit based on the determined ranking. Cell-level processors can handle fewer time-sensitive tasks, as will be discussed in further detail below.

[0099] Overview of Electronic Structure - Switching Cell Circuit

[0100] In some embodiments, there is a system in which energy storage modules are selectively connected in series as needed to generate a desired output voltage. This system may be referred to as a reconfigurable battery system.

[0101] In some embodiments, the electronic components support an electronic switching element that is selectively operated to connect to or bypass any one or more battery cells in a series arrangement. Operation may further require selective bypass and reconnection, wherein bypassing the battery cells from the series arrangement is performed reversibly, such that the battery cells can subsequently be selectively reconnected to the series arrangement. Selectively bypassing the cells from the series arrangement enables different connection states and allows, for example, variations in the output voltage of the series arrangement. Operation of the electronic switching element is possible during the charging and / or discharging of one or more battery cells in the series arrangement.

[0102] When three battery cell units are present, the connection states can include: a first state, a second state, and a third state. In the first state, the first and second battery cell units are connected in series and the third battery cell unit is bypassed. In the second state, the first and third battery cell units are connected in series and the second battery cell unit is bypassed. In the third state, the second and third battery cell units are connected in series and the first battery cell unit is bypassed.

[0103] When there are four battery cell units, the state can include the three states mentioned above, as well as the fourth and fifth states. In the fourth state, the first, second, and fourth battery cell units are connected in series and the third battery cell unit is bypassed. In the fifth state, the first, second, third, and fourth battery cell units are connected in series.

[0104] By controlling the number of battery cells connected in series, the electronic component can control the voltage generated at the output of one or more electronic components.

[0105] In some embodiments, the electronic component supports electronic parts that are operated such that, in addition to connecting or bypassing any number of battery cell units in a series arrangement, individual battery cell units or groups of battery cell units can be reversed. In one control state, such an electronic component may have a first output terminal with a relatively positive potential relative to a second output terminal. In a second control state, such an electronic component may have a first output terminal with a relatively negative potential relative to the second output terminal. The reversal of the battery cell output terminals can be performed using a circuit arrangement such as an H-bridge circuit.

[0106] In some embodiments, the switching component can be operated such that multiple battery cells are connected in series, and one or more battery cells are connected to a resistive element for discharging or reducing the charge on these one or more battery cells. In another embodiment, the switching component on the electronic assembly can be operated such that multiple battery cells are connected in series, and one or more battery cells are connected to an energy transfer element for transferring energy from a first battery cell to one or more other battery cells, or transferring energy from one or more other battery cells to a first battery cell. The energy transfer element may include, for example, one or more of a capacitor, inductor, transformer, DC / DC converter, and / or battery.

[0107] harmonic

[0108] Embodiments of the present invention relate to the control of the output voltage profile from a series-connected energy storage module, which closely fits a time-varying waveform, such as a sine curve. Specifically, the embodiments address the mitigation of harmonics generated when series-connected cells are switched. Switching series-connected cells causes harmonic generation in several ways: first, the switching action produces a square wave voltage waveform with abrupt changes containing high-frequency components, including odd and even harmonics; second, the output voltage waveform is typically not a pure sine wave, which also contributes to harmonic generation. Here, a better “fit” of the waveform reduces harmonics through a closer match to the sine wave.

[0109] An example is an ideal AC sine wave, such as the supply voltage. However, the tightness of the fit is limited by the voltage values ​​of the connected battery cells. For example, when the cells are close to the full SoC, their voltages are higher, which imposes a limitation on how well the "fit" is on the ideal AC sine wave, resulting in undesirable harmonic levels.

[0110] control structure

[0111] Figure 1 An exemplary energy storage system control architecture, typically for a multilevel inverter or reconfigurable battery system, is illustrated. In the depicted system, a controller is present, configured to operate one or more energy storage devices.

[0112] The system also includes a distributed arrangement of communication channels operable to control switching devices for each energy storage module. In this exemplary system, the communication channels are divided into channels with "real-time" signals and "soft-time" signals. The "real-time" signals are typically time-sensitive and involve precise timing of events. Real-time signals are typically transmitted from a single source to all energy storage modules, while soft-time signals are typically sent from multiple sources.

[0113] In situations where system communication speed limitations cause arrival time delays for time-sensitive signals, separate channels for high-speed and low-speed communication signals are useful. In reconfigurable battery systems, this is often due to too many nodes to control, line delays, or the need for extensive computation to determine operating parameters. Any such factor will limit how much harmonics can be reduced without increasing communication speed (often involving expensive hardware such as microprocessors and communication devices).

[0114] In reconfigurable battery systems, real-time signals include control signals used to operate switching devices to connect and disconnect cell connections. Therefore, these real-time signals are those that must be transmitted at high speed to connect and disconnect battery modules in the reconfigurable battery system without short-circuiting any cells or unintentionally disconnecting the output voltage. The gate control signals of MOSFETs in a reconfigurable battery system are examples of real-time signals requiring micron or nanometer-level precision. Control messages broadcast to all cells to control the connection and disconnection of energy storage modules fall into this category. In some embodiments, real-time signals are therefore transmitted over the depicted high-speed communication bus channel.

[0115] In reconfigurable battery systems, soft-time signals are signals that are not time-critical for functionality. Examples of soft-time signals are those that contain data related to temperature, voltage, current, SOC (State of Charge), and SOH (State of Health), as well as other battery parameters or environmental data. In some embodiments, soft-time signals are therefore transmitted on the depicted low-speed communication bus. An example of a low-speed communication bus is a Universal Asynchronous Receiver / Transmitter (UART) communication channel, operable for communicating data at rates up to several seconds. Further examples of soft-time signals include data representing the ranking of energy storage modules and data representing updates to that ranking.

[0116] In some embodiments, there are reconfigurable battery systems with controllers, which include a combination of processing devices, such as two or more microprocessor devices. Figure 1In the distributed system shown, the controller includes a first processor (central processing unit or central controller) that communicates with multiple local processors (cell-level processing devices or cell controllers). The central controller communicates with the cell controllers via a high-speed communication channel and is configured to send timing-related control signals via this channel. The cell controllers communicate with other cell controllers via low-speed communication channels. References to "controller" in this specification refer to control functions that may occur at the central or local processing level. References to "cell controller" or "central controller" refer to control functions that occur at the cell level or central level of the system architecture, respectively.

[0117] In this specification, the reference high-speed channel is intended to refer to a communication bus configured to support at least timing signals, while the low-speed channel is intended to refer to a communication bus configured to support the transmission of cell data.

[0118] The communication speed between the central controller and local controllers (for each cell / node) is the rate at which control messages can potentially be updated to new numbers (e.g., 2 to 3). The communication speed is directly determined by the communication cycle; therefore, a communication speed of 1 kHz has a communication cycle of 1 millisecond. The control cycle is the rate at which each cell's modulation can be controlled, and therefore, the control cycle does not necessarily have to be the same as the control message speed or the communication speed. In most implementations, the communication speed exceeds the time required to process cell ranking because ranking is done in soft time (e.g., every 1 or 2 seconds), while the communication speed is real-time (e.g., 10 kHz or higher).

[0119] Modulation control of the switching circuit of the energy storage module

[0120] Embodiments of the present invention relate to a battery control system. The battery control system includes a circuit module comprising a pair of output terminals, a series of cell modules, each cell module including at least one cell, and a switching circuit configured to define switching states of the cell modules, including a cell-bypass state and a cell-series-connected state. The battery control system also includes a controller configured to control the switching of one or more cell modules to satisfy a target circuit module output voltage. The target output voltage is typically determined by the application of the battery control system and can be, for example, an AC mains voltage source, an electric vehicle motor controller, etc. The controller is configured to operate the switching circuit via a combination of the series connection of one or more cell modules to the output terminals and modulation of the switching state of at least one cell module. The series connection and modulation together allow control of the output voltage to substantially satisfy the target voltage.

[0121] When the target voltage varies over time and / or lies within the voltage thresholds that the series-connected cells can provide, the modulation of the switching circuit enables the output to reach the target voltage thresholds. In this way, the target voltage is substantially satisfied at the output terminals of the circuit module, and furthermore, the generated harmonics are reduced to further improve system efficiency.

[0122] In embodiments of the invention, a desired number of battery cell modules are selected for series connection to meet a voltage target, and the connections occur with predetermined time increments. The time increments can be uniform, fixed, or dynamic. An example of a dynamic time increment can be predetermined, but unequal increments may be ideal, such as for the shape of a time-varying waveform that the output is intended to approximate. Modulation of the series connection of one or more battery cell modules is performed within this time increment. Thus, the series connection of the battery cells occurs at a first frequency, or can be determined, for example, by the first time increment, and the modulated connection occurs at a second higher frequency, or can be determined, for example, by a second shorter time increment. In some embodiments, the second frequency is at least ten times the first frequency.

[0123] In some embodiments, modulation of the switching circuit includes applying pulse width modulation (PWM) to the switching circuits of any one or more energy storage modules. PWM parameters typically include modulation of the duty cycle, or a fixed duty cycle along with a modulated base frequency, or both.

[0124] In some embodiments, modulation of the switching circuitry includes applying pulse density modulation (PDM) to the switching circuitry of any one or more energy storage modules. PDM parameters typically include a time increment, where pulses may or may not be applied, such that the number of pulses can be varied over a time span to fill any ratio of the time increment. In some embodiments, a plurality of pulses are combined to produce a combination of longer and shorter pulses within the time increment.

[0125] In some embodiments, a combination of PWM and PDM modulation techniques is applied to the switching circuit. For example, by combining PDM pulses with PWM pulses within a time increment. In some embodiments, this approach may be preferred, where pulse on / off instances applied to one cell module may be desirable to be aligned with pulse on / off instances of another cell module.

[0126] Note that modulation or switching resolution is based on circuitry and control hardware. In some cases, controlling switching at a rate that introduces significant switching losses is disadvantageous. To manage switching losses, considerations of how frequently to control the switching state may include, for example, combining pulses in a pulse density approach. The resolution is the lowest effective voltage of the lowest-ranked cell, as this produces the minimum step.

[0127] In one exemplary embodiment, PDM-based modulation is implemented according to the principle of minimizing switching losses, and here, pulses in the pulse density are combined into a single pulse within a predetermined time increment. In a modified exemplary embodiment, PDM-based modulation is implemented where pulses are combined into two pulses within a predetermined time increment. In a modified exemplary embodiment, PDM-based modulation is implemented where pulses are combined into three pulses within a predetermined time increment. In a modified exemplary embodiment, PDM-based modulation is implemented where pulses are combined into four pulses within a predetermined time increment. In a modified exemplary embodiment, PDM-based modulation is implemented where pulses are combined into any one of one to four pulses within a predetermined time increment.

[0128] Figure 2A and Figure 2B An exemplary battery system 100 is illustrated, which includes a plurality of battery cell modules 102, a central controller 104 for controlling the operation of the battery cell modules 102, and an output module 106 for measuring and verifying the output of the battery cell modules 102 and / or processing the output to provide a desired output voltage profile. This output profile may be determined based on user input or the voltage requirements of a device or appliance to be powered by the battery system 100.

[0129] In some embodiments, the central controller 104 determines a set of control parameters for controlling the battery cell modules 102 based on input parameters retrieved from the battery cell modules 102, such as the current voltage, maximum charging voltage, and minimum discharging voltage of each battery cell module 102, and the voltage value of the entire battery system 100. Each battery cell module 102 includes a cell controller 108 for communicating with the central controller 104. Any suitable communication protocol can be used. In one embodiment, the central controller 104 uses the I2C protocol to communicate with the cell controller 108 on each battery cell module 102 and the output module 106.

[0130] Control parameters determine when and how each battery cell module 102 operates at any given time. Specifically, control parameters include duty cycle and time offset, as explained in further detail below. In some embodiments, the battery cell module includes a processor configured to control local modules, other modules, and / or share information with other modules for operation. In some embodiments, any of the above-described control functions are shared between the central controller 104 and the controller of the battery cell module 102.

[0131] Each battery cell module 102 further includes a battery cell unit 110 and a switching assembly 112. The switching assembly 112 includes a transistor 114 that selectively connects or disconnects (or bypasses) the battery cell unit 110 and switching control circuitry for controlling the transistor 114. In one embodiment, for example in a "half-bridge" circuit configuration, two power transistors (i.e., MOSFETs) are used for each switching assembly 112, one MOSFET for connecting the battery cell unit 110 and one for disconnecting it. The outputs of all connected battery cell modules 102 are connected in series. Several other example configurations of switching assemblies and cell units are described in PCT application number PCT / AU2016 / 050917, the entire contents of which are incorporated herein by reference.

[0132] exist Figure 2B In one embodiment, the output module 107 includes a set of output switches 125, one or more voltage and current measurement sensors (not shown), and further includes an LC low-pass filter 118 for smoothing out the accumulated voltage and current output of the battery cell module 102. The LC filter 118 is used to provide further stability to the battery system output by reducing voltage variations and / or current spikes caused by switching of the battery cell unit 110. The filter can also be used to smooth any modulated cell switching and produce a substantially average cell voltage very close to the modulation duty cycle. The corner frequency of the filter is selected based on the modulation frequency of the switching circuit. In some embodiments, the filter has an angular frequency higher than the modulation fundamental frequency of the switching circuit. In some embodiments, the corner frequency of the filter is at least one octave higher than the fundamental frequency of the switching circuit. In some embodiments, the filter is a single-pole circuit. However, in alternative embodiments, the filter may have more than one filter stage, such as a two-pole or three-pole circuit. A higher number of poles means that the corner frequency of the filter can be closer to the fundamental frequency modulated by the switching circuit. However, the cost of additional or larger capacitor components, the level of harmonic or modulation suppression, and the filter's response speed may limit what constitutes the optimal filter circuit.

[0133] Output controller 116 communicates with central controller 104 and interfaces with sensors and transistor 125. Alternatively, transistor 125 can be used to disconnect the entire battery system 100 from electrical equipment or appliances (not shown) when instructed to do so by central controller 104, or when a sensor on output module 107 indicates a current or voltage exceeding the expected operating threshold.

[0134] In some embodiments, the controller is configured to implement PDM-based modulation, including modulation of pulses within a period. This means that the cell can be turned on during a full control cycle and turned off during the next full control cycle. In some embodiments, the cell-level controller is configured to control pulses connecting cell connections in a series of cell strings.

[0135] Figure 15 A shows an example based on PWM modulation. Figure 15 C illustrates an example based on PDM modulation. Figure 15 In the example shown in C, the cells are connected with a 100% duty cycle and have various pulse frequencies to simulate an effect similar to a variable PWM duty cycle. In some embodiments, the central controller is configured to instruct the position controller to apply pulse frequencies based on cell ranking. Figure 15 In example C, there are 10 control cycles within a 1ms time increment, therefore the cell contribution is as follows:

[0136] For example, ranking 1 could be 100%, ranking 2 could be 90%, thus producing results such as Figure 4 The overview of cell contribution difference (CCD) based on PDM shown is as follows: Figure 16 As shown in the diagram. For a control cycle time iteration of 0.1ms, 0-10 pulses can exist within a 1ms timeframe. This means that the CCD can only be 10% or higher. This implies that the minimum difference between rankings is 10%. In some embodiments, when using a Balancing Weight Factor (BWF), the resulting CCD profile and therefore the cell contribution assigned to adjacent rankings must be rounded up or down to the nearest multiple of 10%. For example, for a BWF of 0.75, the initial calculation of CCD between rankings is 15%, but since pulses can only achieve CCD multiples of 10%, the actual CCD assigned or used will have to be 10% or 20%. Figure 17 The table shows an example of rounded PDM contributions based on ranking.

[0137] Note that rounding can be avoided by carefully selecting the length of the time increment or by using a combination of two or more time increments. For example, using a full-cycle pulse can achieve 85% cell contribution, with 17 pulses in a 20-control-cycle time window increment, or two communication cycles each with 1ms. However, this will result in greater harmonics and current ripple due to the longer pulse width. Applying a fixed pulse frequency over a window of two communication cycles is also less flexible than applying two different pulse frequencies over those two communication cycles.

[0138] Another significant difference between PWM-based implementations and PDM-based cell contributions is how small the pulse period can be, using the same communication and control speeds. PWM-based contributions achieve smaller pulse periods, providing less current ripple and lower harmonics. PWM-based contributions also allow for finer control over the frequency of the current pulses experienced by the ripple. This allows for manipulation of ripple impedance and the acquisition of benefits such as extended ripple lifetime and less heat generation.

[0139] Figure 18 An example of PDM- and PWM-based modulation is shown compared to existing techniques without modulation. The relationship between communication speed, control cycle, and their impact on the resolution of the stepwise approximation on an ideal AC sine waveform can be observed.

[0140] Ranking

[0141] The utilization rate of any battery cell in the system will depend on many factors, including the cell's own parameters and environmental parameters. In some embodiments, cells are ranked according to the order in which they are considered to be most fully utilized. The ranking of any cell may also change over time based on cell performance and varying environmental conditions. Cell data is used to determine the ranking of cells in a set of cells, and cell data typically includes one or more of the following: voltage, current delivery, capacity, state of charge, temperature, age, measured lifespan, predicted lifespan, temperature, rate of temperature change, internal resistance, location in a series arrangement, health status, and / or cell stress. This list is merely exemplary, and other factors may be included as desired by the system operator to determine the ranking of cells in the system.

[0142] In some embodiments, the reconfigurable battery system includes two or more cell processors configured to determine cell data for one or more cells under the control of each cell processor and transmit the determined cell data to one or more other cell processors. In such embodiments, at least one cell processor is configured to determine a ranking of each cell based on the received and determined cell data and transmit the ranking to one or more other cell processors. However, in other embodiments, each cell controller is configured to determine a ranking of each controlled energy storage module, since each cell controller will determine the ranking of all cells based on the received cell data.

[0143] In some embodiments, a combination of cell data can be used to determine cell ranking. For example, the ranking of each energy storage module can be determined based on a weighted combination of two or more defined parameters in the cell data.

[0144] In some embodiments, the ranking of energy storage modules determines whether the module is connected to or bypassed from the circuit, and whether the module should be modulated. In one exemplary embodiment, a central controller is configured to determine the number of cells that should be connected in series based on a target output voltage. The target output voltage may be indicated by output control data such as a target voltage, the number of cells to be connected, or a ranking number indicating a threshold, wherein the number of cells reaching that threshold will be connected. The cell controller is configured to receive the output control data and operate the switching circuit accordingly.

[0145] Target voltage limit

[0146] In some embodiments, a target voltage exists, which is the effective output voltage. For example, the voltage measured at the output of a reconfigurable battery system. The output voltage may be subjected to one or more filters used to smooth the voltage waveform. Such filters are typically used to modify a modulated voltage, or a modulated voltage component, or a high-frequency time-varying voltage or voltage component, and to produce a smoothed voltage or a low-frequency time-varying voltage. In some embodiments, the target voltage is determined from the measured output voltage (i.e., in the closed loop). In some embodiments, the target voltage is predetermined based on a known output voltage. In some embodiments, the voltage target is stored in a database. In some embodiments, the voltage is determined based on a modeled time-varying waveform and a specific time or phase increment of that waveform. In some embodiments, the target voltage is a combination of one or more cell voltages and one or more modulated cell voltages. In some embodiments, the target voltage...

[0147] Figure 3 illustrates an example of steps executed by a controller that performs modulation control and series connection control of the switching circuit based on a cell ranking determined in the reconfigurable battery system. This modulation control allows for variable output voltage and power delivery from one or more energy storage cells, enabling finer control over the target output voltage. Thus, variability can further depend on the ranking of the cells to which modulation control is applied. It should also be noted that, according to the described steps, not all steps occur on the same timescale, and some steps may occur before others. For example, steps A1-A4 may be determined at a relatively high rate (e.g., an update rate of 1 kHz), while steps B1-B3 may occur at a relatively low rate (e.g., 1 Hz).

[0148] Steps A1-A4

[0149] Regarding the following steps, the communication and communication speed between the central controller and the local controller are referred to as the speed at which control messages can potentially be updated. The communication speed is directly determined based on a communication cycle of 1 millisecond at a communication speed of 1 kHz. The control cycle refers to the rate at which each cell can be turned on, off, or modulated. The control cycle speed does not need to be the same as the control message speed or communication speed, because switching control can be directly operated by the cell controller.

[0150] Step A1: The central controller determines the target output voltage for the next communication cycle. For example, if the desired output is a time-varying AC sine wave, the target voltage will be determined by the voltage at a specific phase increment in the sine wave.

[0151] Figure 4 and Figure 6 An example of an ideal AC waveform is shown, where the 9V voltage is targeted based on a simplified 12V peak value to more easily illustrate the embodiment. Note that the control cycle frequency is intentionally low for the purpose of simply illustrating the concept of the invention. In practical implementations, the control cycle frequency is typically higher than 50 or 60 Hz for AC waveforms, such as 20 kHz or 50 kHz or higher.

[0152] Step A2: The central controller sends a control message to the local cell controller (e.g., a number between 0 and 6 indicates the number of cells to be connected in series to achieve the target voltage). The cell controller receives the control message and compares it with stored ranking information to determine whether to connect or bypass the cells in the series connection. For example, a specific cell in the number of cells to be connected is determined by the ranking of each cell, with the lowest-ranked cell given priority for connection. If the cell module's ranking is lower than or equal to that in the control message, the cell should be connected; otherwise, if it is higher, the cell should be bypassed.

[0153] In response to this target output voltage, the controller sends a message to all battery modules. This message contains multiple battery modules that must either assume a predetermined switching state or simply assume the target output voltage. At the local controller, based on a comparison between the control message sent by the controller and a specific ranking, a switching state is defined for each battery module based on the received state or target voltage, and ultimately each battery module assumes this switching state to provide the required output voltage.

[0154] In some embodiments, the control message includes the desired output voltage. In other embodiments, the control message includes multiple battery modules that must assume specific switching states. Other control messages containing data indicating the target voltage are possible.

[0155] In some embodiments, the control message is broadcast by the central controller to each cell controller. In some embodiments, the control message is sent only from the central controller to the first cell controller, and the first cell controller receiving the control message is configured to transmit the control message to the second and any other cell controllers.

[0156] Note that this step uses 0-6 as an example of a control message. This is a simplification because 0-6 only applies to the positive half of an AC sine wave. For the second / negative half of an AC sine wave, the number can be between -6 and 0, and if each cell is capable of such a reversal, the local controller receives the negative sign as an instruction to reverse its polarity to achieve a negative output voltage. Alternatively, the negative sign indicates the H-bridge at the end of the contained cell string to configure the switching to reverse the polarity of the total output voltage.

[0157] Step A3: Each cell controller is configured to compare the control message received (from step A2) with a ranking or target determined for the local cell. Each cell controller is configured to operate on a signal that allows the switching circuit to include or bypass the cell based on the comparison output. However, the switching does not take their determined state before step A4, because it is important that the switching state changes only in response to the synchronization signal received by all cell controllers.

[0158] Step A4: Each cell controller is configured to receive control messages (from step A2) and apply arbitrary modulation to the switching circuit. This step generates the output voltage.

[0159] In some embodiments, control messages are transmitted at a communication speed that may or may not be at the frequency of the control cycle loop (e.g., 50 kHz). In some embodiments, control messages are updated in each communication cycle, but may not be updated in each control cycle. The update rate will depend on any communication speed limitations between the central controller and the cell controller.

[0160] exist Figure 6 In this configuration, the communication period is 1 ms, and therefore the communication speed is 1 kHz, while the control period is 0.1 ms, and therefore the control frequency is 10 kHz. A limitation of the control period update rate is that the modulation parameters (duty cycle and / or base frequency) will remain fixed between updates.

[0161] In an example where modulation is not used and 9V is the desired output voltage, cells 5 and 6 are included, which sum to a 7.6V output voltage, and the control message in the communication cycle is 2.

[0162] In the example where modulation is not used and 9V is the desired output voltage, the cell can be modulated between 0% and 100% of its output voltage (depending on the step resolution determined by the ability of the cell controller or switching circuit to generate the modulation resolution). In the case of modulated cell output, including batteries 4, 5, and 6, the sum of their output voltages is 8.99V, and the control message for the control cycle is 3.

[0163] Steps B1-B3

[0164] See you again Figure 3B :

[0165] Step B1: Each local controller is configured to measure the voltage of one or more controlled cells. In some embodiments, this step is repeated at a rate faster than the cell control update rate, and may be performed at a rate useful for determining any particular cell attribute that is useful for at least cell ranking purposes.

[0166] Step B2: The controller ranks all available cells based on its measured voltage or preferred ranking parameters discussed earlier. Note that this step does not need to occur within a control cycle; the rankings are typically determined and updated at a much slower rate than the control cycle frequency.

[0167] Note that the number of available cells can be determined based on battery parameters indicating available or usable cells. An example of an unavailable cell is one that falls outside predetermined criteria. In one exemplary embodiment, a cell that has exceeded its temperature limit is excluded from the selection of usable cells and is therefore not ranked or ranked lower, thus limiting or excluding its use. A cell determined to be undesirable can later become desirable again if, for example, the relevant parameters are improved within predetermined criteria. Figure 5 This paper outlines various considerations that can be used by controllers to rank battery cells, including one or more factors, combinations thereof, weighted combinations thereof, or trade-offs between factors.

[0168] Step B3: The controller determines the modulation profile to be applied to one or more cells.

[0169] Note the order of these steps: It is not strictly required that these steps occur in the exact order shown above. For illustrative purposes, the steps are described sequentially. For example, in step B3, the central controller receives or determines the duty cycle for each rank (and therefore the available cells), a step that can even occur before step A1 and can be arbitrarily set via user input. The transmission of control messages in step A2 could also occur in any other step, as it is continuous and does not require information from other steps. For example, step B3 could occur simultaneously to obtain a profile of duty cycle differences satisfying multiple constraints that can be imposed in step B3.

[0170] Therefore, in some embodiments, the controller is configured to determine the output voltage of the target circuit module and control the modulation duty cycle and / or frequency of the switching state of at least one cell module to satisfy the output voltage of the target circuit module.

[0171] In some embodiments, the controller is further configured to determine the output voltage of the target circuit module and, based on the determined ranking, control the modulation duty cycle and / or frequency of the switching state of the cell module to satisfy the output voltage of the target circuit module.

[0172] In some embodiments, the controller is further configured to determine the output voltage of the target circuit module and, based on the determined ranking of each cell module, preferentially assign higher modulation duty cycle and / or frequency of the switching state to those cell modules with higher ranking, and preferentially assign lower modulation duty cycle of the switching state to those cell modules with lower ranking.

[0173] In some embodiments, the controller is further configured to determine the output voltage of the target circuit module and control the modulation duty cycle and / or frequency of the switching states of two or more cell modules to meet the target voltage.

[0174] In some embodiments, the controller is further configured to determine the output voltage of the target circuit module, determine a (balanced) weighting factor that assigns modulation duty cycle priority to each cell module based on the determined ranking, and control the modulation duty cycle and / or frequency of the switching states of each ranked cell module based on the weighting factor. The weighting factor defines a distribution across the ranked cell modules. In some embodiments, the distribution across all cells is uniform. In other embodiments, the distribution is a non-linear distribution across the ranked cell modules. In some embodiments, the distribution across available cells is dynamically adjusted based on cell data, such as that referenced for cell ranking determination.

[0175] In some embodiments, the target voltage includes a time-increment target voltage having discrete voltage levels for each time increment, and modulation includes a modulation base frequency time greater than the time increment. For example, the modulation base frequency is at least 1.25, 1.5, or 2 times the time increment. In some embodiments, the time increment is limited by a central processing unit configured to update the target output voltage at a rate that indicates how many cells should be connected in series and thus substantially update the target output voltage.

[0176] The following discussion provides further details on determining the modulation duty cycle and / or frequency for each ranked cell module.

[0177] Modulation Overview

[0178] This modulation profile is based on multiple considerations and the profile itself can be applied to one or more cell modules in a reconfigurable battery system.

[0179] In some embodiments, the modulation profile is based on a duty cycle difference (DCD) profile. In such an embodiment, the controller determines the DCD between cell modules with adjacent ranks, thereby defining a duty cycle for each rank required to achieve the target voltage. Figure 4 A table showing an example of a duty cycle difference overview is provided.

[0180] In some embodiments, the Balance Weighting Factor (BWF) is applied to all cell modules. In other embodiments, the BWF is applied to a range of cells. In some embodiments, cell selection is determined based on cell ranking or cell parameters, which indicate that some cells require more or less load than others. In some embodiments, the controller applies a Balance Weighting Factor (BWF) between 0 and 1. To utilize all cells, the BWF should be non-zero so that the lowest-ranked available cell is not assigned a 0% modulation duty cycle.

[0181] An example calculation of the duty cycle difference is as follows: DCD = (1 / (total number of cells - 1)) x 0.75 (BWF) x 100%

[0182] Therefore, for 6 cells, for each cell, the example DCD = 15%.

[0183] Note that there are many alternative ways to calculate DCD, such as using substitution equations, or simply setting a fixed DCD arbitrarily based on user input. DCD only indicates the existence of differences in modulation data between ranks.

[0184] In some embodiments, the controller is further configured to measure the voltage at the output terminal and adjust one or more modulation parameters for any one or more cell modules based on the measured voltage. In one exemplary embodiment, the controller is configured to measure the output voltage once modulation of one or more cell modules has occurred. Due to variations in cell performance or other environmental factors, the measured voltage may be higher or lower than a target voltage. The controller is configured to adjust the modulation of one or more cell modules based on any measured difference by, for example, adjusting one or more modulation parameters. If the output voltage is lower than the target voltage, the controller may increase the modulation duty cycle of one or more cell modules. Conversely, if the output voltage is higher than the target voltage, the controller may decrease the modulation duty cycle of one or more cell modules.

[0185] In some embodiments, the controller is configured to measure the output voltage from one or more modulated cell modules and adjust the modulation parameters of the cell modules based on any measured difference between the output voltage and a target voltage.

[0186] In some embodiments, the controller is configured to compare a measured output voltage with a target output voltage and adjust the modulation duty cycle of any one or more cell modules only if the determined difference is higher than a threshold voltage. In some embodiments, the threshold voltage depends on the load connected to the output of the reconfigurable battery system.

[0187] A smaller BWF means a smaller spread between duty cycles that can be applied to cell modules with adjacent rankings. Conversely, a higher BWF results in a larger duty cycle variance profile. If the BWF is too high, and therefore the duty cycle variance profile is too large, the total voltage that can be provided by including all available cells may be lower than required because some cells are directed to be modulated at low duty cycles, thereby giving up some potential from that cell. In this case, more cells are needed to achieve the target output voltage. For example, in Figure 4 and Figure 6 If the BWF is higher than 0.75, then even if all 6 cells are included, the target voltage of 12V cannot be achieved.

[0188] In some embodiments, the controller is configured to determine the maximum BWF of the target output voltage and control the cell module by limiting the BWF accordingly. In some embodiments, the controller is configured to measure the maximum output voltage of the reconfigurable battery system and determine the maximum BWF based on the maximum target output voltage. For example, the controller can check if the BWF is too high by measuring the output of all summed cell module voltages and determining whether the sum is greater than or equal to the peak target voltage. If the sum is less than the desired target peak output voltage, step B3 can be repeated until the constraint of the ideal BWF satisfying the maximum peak target output voltage converges. In some embodiments, other constraints are imposed, and in this specification, the process of determining these other constraints is referred to as the "DCD / BWF optimization step".

[0189] Duty Cycle Difference (DCD) Overview (Step B3)

[0190] Figure 8A and Figure 8B A table showing profile information is provided, including differences in DCD profiles. These differences can be used to control cell usage over time or to control cell usage so that some cells are used disproportionately more than others. More-used cells typically refer to a more aggressive profile with a higher BWF. Figure 8A The diagram shows that the highest-ranked cell can have a 100% duty cycle (when connected), while the lowest-ranked cell, ranked 6th, can only have a 5% duty cycle (when connected). This increases the inconsistency between higher and lower-ranked cells, causing the cell's contribution to the output to be controlled to converge to SOC or capacity. Figure 8B The data shows that lower-ranked cells have similar duty cycles to higher-ranked cells.

[0191] A higher BWF may be desirable for cell balancing. For example, when a cell has a higher voltage, it may be desirable to include that cell in a switching series connection most frequently. Therefore, in some embodiments, cell parameters are used to determine the applicable desired BWF.

[0192] Lower BWF may be desirable for cells to minimize connections. Figure 8A and Figure 8B In the example, Figure 8A A more radical overview and Figure 8BA less aggressive profile requires more cells (3 cells in this example) to achieve the same target output voltage (or the best possible fit to the target output voltage), which results in fewer cells (2 cells in this example) being needed to achieve the same target output voltage. This is because a more aggressive profile leads to a larger difference in duty cycles assigned to adjacent ranks, and therefore a steeper drop in cell contribution at lower ranks. For example, Figure 8B The less radical scenario shown is the opposite of the more radical one.

[0193] Connecting more cells may be desirable because it involves a more uniform heat distribution in the aged cells to provide improved battery system life. However, if some cells age faster than others due to overuse or exposure to medium to high temperatures, these cells may fail before the others, and once a threshold number of cells are determined to be unusable or unsuitable, the entire battery will fail or require maintenance. Therefore, optimal BWF can be an evolutionary goal based on determined cell health parameters and priorities.

[0194] One exemplary application is electric vehicle battery charging or other similar high-current charging environments, where charging the battery to 100% capacity means faster charging because a high level of accuracy is required in this situation to maintain performance while minimizing damage from overcharging during balancing or charging to 100%. A more aggressive BWF profile achieves this better by using lower-ranked cells at lower duty cycles (when ranking is at least partially based on voltage or SoC), and therefore does not have as much overcharge and subsequent overcorrection during balancing at or charging to 100% SoC. On the other hand, for a less aggressive BWF profile, lower-ranked cells have similar duty cycles to higher-ranked cells, in which case balancing can be achieved more slowly given the same accuracy requirements. More aggressive profiles can be used in applications where charging / discharging occurs at very high currents, such as fast charging EVs with very high currents or fast discharging with high current spikes, such as in electric motor drive applications. The balancing rate should ideally match the charging or discharging rate. This means that if the battery needs to be discharged within 20 minutes, a faster balancing rate is required compared to discharging the battery within 2 hours.

[0195] Conversely, fewer cells involved may lead to more efficient battery use because there is less potential drop across the cell terminals, which is especially significant when the current drawn from the battery is high (such as during sudden EV acceleration) or when the cells are less healthy or older and have higher internal resistance. During EV acceleration, the battery experiences an increase in current draw and a decrease in voltage, which can cause the battery to become less efficient. The voltage and current behavior of an EV battery during acceleration depends on the specific design and components of the battery system and the vehicle's power requirements. The increase in current draw leads to a decrease in battery voltage due to the battery's internal resistance, and the exact relationship between current draw and voltage decrease will vary depending on the specific design and construction of the battery and the operating conditions.

[0196] Involving fewer cells also means that there are more redundant cells available in cases where some cells first reach 0% SOC or experience failures (such as thermal runaway of cells that need to be disconnected). Therefore, a less aggressive profile tends to improve system reliability, and it is rare for applications to require an overly aggressive balance factor.

[0197] Figure 9A and Figure 9B Alternative embodiments are shown where the cell usage is determined solely by DCD. DCD can be either linear or nonlinear cell profiling. A nonlinear DCD profile means that the difference between adjacent cells is not constant across all cells. A nonlinear profile may be desirable when a linear profile would involve too many cells to achieve the target output voltage (such as peak AC voltage).

[0198] Figure 10A , Figure 10B and Figure 10C DCD profiles are shown separately, including linear, less aggressive nonlinear profiles, and more aggressive nonlinear profiles. Figure 10A The linear profile has drawbacks, where the voltage output from lower-ranked cells drops very quickly, potentially reducing the total output voltage even when all cells are connected. In such a case, Figure 10B The nonlinear DCD profile can be overcome by using higher-ranked cells (such as ranked 1 or 2) that are used at 100% or close to 100%, while the lowest-ranked cells (such as ranked 5 or 6) can be used much less, at close to 0%.

[0199] Nonlinear DCDs offer the following advantages: fewer cells are needed to achieve the target output voltage, and they also use lower-ranked cells with smaller profiles than linear DCDs. This may be desirable if the cell temperature is too high or the state of charge (SOC) is too low, but the circuit still requires them to meet the desired target output voltage.

[0200] To ensure the system can meet the target output voltage, the sum of the voltages of the connected cells, as a function of their modulation frequency, must be greater than the target voltage. In some embodiments, the controller is configured to control the duty cycle variation by the ratio of the number of cells to the target output voltage. For example, a limited number of cells that may barely meet the target voltage requirement when all cells are at 100% will not be able to have a large DCD.

[0201] Different types of nonlinear profiles can be suitable for different scenarios. Figure 10A The non-linear profile is shown, where higher rankings remain close to 100% for a longer period until they drop rapidly at the lowest rankings. Figure 10C The nonlinear profile is shown, where the duty cycle begins to drop sharply at the highest rank.

[0202] Since duty cycle is directly related to power output, and especially when a relatively high level of power output with a relatively small number of cells is desired, a less aggressive nonlinear profile is preferred for delivering a large output power. A more aggressive nonlinear profile is desirable when the output power is low or when more cells are needed without heavy loading.

[0203] In some embodiments, the controller is configured to control dynamic cell contribution. For example, dynamic DCD and / or BWF. The dynamic duty cycle, modified from the static duty cycle derived from any DCD profile, can be calculated using the following exemplary formula: When Rb > Rl, dd = (Rb - Rl) c + dl, and if dd > 1, then set dd = 1. in: dd is the dynamic duty cycle. Rb is the ranking of broadcasts. Rl is the local ranking. c is a coefficient used to scale the difference to [0, 1], and dl is the static duty cycle derived from the updated linear DCD profile in step B3.

[0204] This equation is based on the difference between the current ranking and the new ranking, and modifies the current cell contribution based on a scaling variable (c), which can be used to set the rate at which the cell contribution changes. A numerical example is shown below: dl = 25% Rb = 10 Rl = 3 C = 0.5 dd = ((10 - 3) 0.5) + 25% = 375% If dd = 1, then dd > 1 = 100%. dl = 25% Rb = 4 Rl = 3 C = 0.5 dd = ((4 - 3) 0.5) + 25% = 50%

[0205] For dynamic duty cycles, the higher-ranked cells will have an increased contribution, thus providing more voltage until they reach 100% contribution. The downside is that there will be increased processing demands from the controller to calculate the number of cells needed to meet the target voltage.

[0206] The output voltage profile that produces a more closely matched ideal AC sinusoidal waveform voltage output reduces harmonics in multilevel inverters or reconfigurable battery systems. Figure 11 An example of a more aggressive balance profile (thus including more cells) is shown, which may result in a better fit to an ideal AC sine waveform with reduced harmonics. In this example, the controller is configured to dynamically control the cell contribution at an update rate that allows for a close match to the target output voltage. A constraint on the controller's ability to control cell connectivity and contribution is that the total output voltage from all available cells after applying the duty cycle must be higher than the desired maximum peak voltage of the AC waveform (typically 240V in North America and 230V in Europe). Having at least some redundant cells is also critical for system reliability and lifespan. This reduces the controller's ability to provide a significant contribution from some cells relative to others; the profile cannot be overly aggressive. This constraint limits how much the DCD or BWF can or should be limited.

[0207] Trade-offs (DCD / BWF optimization step B3 - Determine DCD overview)

[0208] For the reasons mentioned above, there is a trade-off between an aggressive profile with a larger DCD or larger BWF and a less aggressive profile with a lower DCD or lower BWF. Figure 12 This concept is shown, and is Figure 3B Detailed inspection of step B3 in the document. Figure 12 The left side shows an overview example of a linear DCD, while Figure 12 The right side shows an example of a nonlinear DCD overview.

[0209] In an exemplary embodiment, the following equation is shown as the algorithm used to derive the DCD to be used:

[0210] Starting point DCD (arbitrarily set to 10%) X [((0.5-1.5) fitting + (0.5-1.5) speed of precise balancing + (0.5-1.5) more cells for uniform temperature diffusion / 3] [(0.5-1.5) Communication speed limit + (0.5-1.5) Desire for fewer cells due to] Typical high-current applications + (0.5-1.5) due to availability or wanting more redundancy with fewer cells to be used) / 3] = actual DCD.

[0211] In this embodiment, a fixed value / factor is set if the battery is frequently used at high currents (such as in EV racing). In other embodiments, this factor can be a time-varying value. In another embodiment, the equation used as the algorithm for calculating the BWF to be used is shown below:

[0212] Starting point BWF (arbitrarily set to 0.75) [(0.5-1.5) Fit + (0.5-1.5) Precisely Balanced Speed ​​+ (0.5-1.5) More Cells for Uniform Temperature Spread / 3]X[(0.5-1.5) Communication Speed ​​Limit + (0.5-1.5) Desire for Fewer Cells Due to Typical high-current applications + (0.5-1.5) due to availability or wanting more redundancy and fewer cells to be used) / 3] = actual BWF.

[0213] It is possible to have an implementation Figure 12 Many other formulas / equations of the same nature as the DCD / BWF optimization step (step B3) shown.

[0214] When determining the cell contribution to be applied to the battery cell, there are factors that must be prioritized or that impose limitations. Therefore, in some embodiments, the controller is configured to first determine the cell contribution based on limitations and then based on priorities. Limitations include: • Maximum expected output voltage (maximum target output voltage); and • Maximum control frequency.

[0215] The maximum output voltage setting or limit is the minimum sum of the total duty cycles. Due to limitations on how quickly switching states can be changed without causing malfunctions or degradation, the maximum control frequency definition limits the resolution of the modulation duty cycle.

[0216] In some embodiments, limitations are predefined and provided to the controller as a basis for further determination. In some embodiments, the controller is configured to determine one or two limitations based on data derived from the system. For example, a method for determining the cell duty cycle includes starting with a modulation duty cycle linearly applied to all cells. The method also includes progressively evolving the applied modulation duty cycle based on ranking or other factors, such that the duty cycle of each cell deviates from linear application to other forms. The total output voltage is determined by cell characteristics and data provided to the controller as part of a feedback loop. Thus, the controller is configured to use the data in the feedback loop to indicate whether to continue or restore any progressive changes in cell contribution.

[0217] When the nonlinear cell contribution is determined, the requirement for variation in feedback control of the cell contribution is typically reduced. However, feedback can be applied in situations where the cell contribution may need to be adapted or optimized over time.

[0218] Adaptive DCD / BWF

[0219] The above discussion and Figure 12 Some of the constraints shown are time-varying constraints. For example, during acceleration of an EV vehicle, the current suddenly increases. During acceleration, the electric motor requires a large amount of current to generate the torque needed for acceleration. This results in high current consumption from the battery. On the other hand, during steady-state driving at a constant speed on flat ground, the power demand is relatively low and the battery current consumption is also low. During regenerative braking, current consumption can also be low, where the electric motor acts as a generator to convert the vehicle's kinetic energy back into electrical energy to be stored in the battery. In general, the current consumption from the battery varies depending on the electric motor's driving conditions and power demand.

[0220] Another example of time-varying constraints is the number of cells required to be connected at the peak of an AC waveform, with the expectation of having several redundant cells. One example calculation is that if the cells are fully charged at 4.2V, only 64 cells need to be connected to achieve a peak AC voltage of 270V. As they gradually discharge, the number increases until 100 cells are connected at 2.7V, each providing 270V output (64 x 4.2 = 270V), when the cell cells are almost fully discharged. Therefore, as the cells discharge, more cells need to be connected in series. If 20 redundant cells are needed, then 120 cells are required. If a DCD or BWF strategy is applied, most cells will operate with a duty cycle of less than 100%. If the controller determines that 110 cells are required to be connected in series after modulation is applied, and there are still 120 cells available (with 20 planned redundant cells), then the DCD or BWF can be reduced until only 100 cells are required to be connected. Therefore, the ability to quickly and accurately balance cells is improved by having more cells in the battery system, because an aggressive profile (large DCD / BWF number) significantly reduces the effective voltage of lower-ranked cells compared to a smaller DCD / BWF value.

[0221] It is also worth noting that not all cells are available at all times, and the number of cells available at any given time may not remain constant. For example, using... Figure 4 In the example, cell 1 is unavailable (e.g., too hot or the voltage is too low or will become too low), so the controller is configured to temporarily disable the use of that cell. Such a threshold can be predetermined by the controller to impose one or more variables on the number of available cells. This constraint is also... Figure 12 As shown in the image.

[0222] Figure 13 The left side shows an exemplary overview for implementation by a controller based on adaptive DCD / BWF. An inverse correlation exists between the current requirement and the ideal DCD / BWF for the constraints. It is also shown that this relationship does not necessarily need to be linear. Figure 12 Some of the constraints listed may be time-dependent, while others are not. In some embodiments, the controller is configured to implement an algorithm based on ideal dynamic DCD / BWF for each time step, which combines a trade-off between time-varying constraints and time constant constraints. Figure 14 This shows an example of how such an adaptive DCD would look over time.

[0223] In an exemplary embodiment, the controller is configured to implement a mathematical relationship to determine an adaptive DCD based on time. In other embodiments, a similar equation can be used to derive an adaptive BWF, wherein:

[0224] Dynamic DCD = Statistical DCD (e.g., 10%) ((better fit factor (e.g., 0.5–1.5)(t) + velocity (t) of the accurate balance factor + more diffusion (t) of the temperature factor + any other factor)) / (number of factors)) ((low communication speed factor (t) + higher current factor + availability or redundancy factor (t) + any other factor) / number of factors). And:

[0225] Dynamic BWF = Statistical BWF (e.g., 75%) ((better fit factor (e.g., 0.5–1.5)(t) + velocity (t) of the accurate balance factor + more diffusion (t) of the temperature factor + any other factor)) / (number of factors)) ((low communication speed factor (t) + higher current factor + availability or redundancy factor (t) + any other factor) / number of factors).

[0226] To implement any or more of the control strategies described above, the controller is configured to determine the lowest effective voltage. This could, for example, come from the lowest-ranked cell. The lowest cell voltage provides the smallest voltage step when not modulated. The resolution (defined by the lowest effective voltage of the lowest-ranked cell) determines how closely your step-through output voltage profile can approximate the ideal AC sine wave and thus minimize harmonics.

[0227] Figure 19 The example provided illustrates six cells with a minimum cell voltage of 2.3V. To improve the ability to meet target voltages below the required resolution of 2.3V in a ranking-based distributed gate drive communication scheme, the contribution of one or more of the included cells needs to be less than 100%. This can be achieved, for example, by assigning different contributions to different cells based on their ranking. This approach is possible if some cells can contribute less than 100% via one of the following methods:

[0228] First, reduce the control cycle so that the control frequency is faster than the communication speed. Figure 19 In example A, the control cycle is 10% of the communication cycle duration; the control cycle is 0.1 ms, and the communication cycle is 1 ms. For any given cell, such as cell 1 (measured at 2.3V), by reducing the control cycle to less than the communication cycle, the cell can be turned on or off multiple times. Note that the control cycle needs to be less than 50% of the communication cycle so that the cell turns on and off once within that communication cycle, resulting in cell 1's effective voltage being 2.3V, 1.15V, or 0V within a 1ms communication cycle. Further reducing the control cycle duration achieves even higher resolution. Figure 19In example A, the control cycle is 10% of the communication cycle that provides 2.3V x 10% = 0.23V.

[0229] Secondly, modulate any one or more battery cell modules to provide a contribution between 0% and 100%, such as Figure 19 As shown. Figure 20 This demonstrates that the PWM-based modulation in this embodiment has advantages over PDM-based modulation. When the control cycle is 10% or 100% of the communication cycle, the system resolution is not limited because the cell can be turned on with a 10% duty cycle even when the control cycle and communication cycle are the same. Therefore, as... Figure 20 A and Figure 20 As shown in B, when the control cycle is Figure 19 When A is 0.1ms, or if the control period is Figure 20 As shown in B, 85% of the effective voltage of the battery cell can be achieved within 1ms.

[0230] Note that having a communication speed faster than the control speed offers no benefit. For example, if the communication cycle is 1ms and the control cycle is 1.1ms, when the control message is updated from 3 (at 9.0ms) to 2 (at 10.0ms), the cell configuration (how many cells are included or bypassed) cannot be updated in time to reflect the change in the control message because the update can only occur in 1.1ms, resulting in the cell configuration remaining unchanged despite the change requested by the control message.

[0231] In environments with low communication speeds, PDM-based modulation is provided with a control speed at least twice as fast as the communication speed (and preferably even faster to achieve more levels). This modulation is a combination of the following: a) the ability to allocate cell contributions other than 0% and 100%, which is thus achieved; b) assigning different contributions to cells of different ranks. Furthermore, the combination of a and b allows for a rank-based distributed gate drive communication scheme to achieve better harmonics than existing methods.

[0232] Furthermore, given the slow communication or control speeds, PWM modulation offers the following combination: a) the ability to allocate duty cycles between 0% and 100%, thus enabling; b) the allocation of different duty cycles to cells of different ranks. The combination of a and b allows for a rank-based distributed gate drive communication scheme to achieve better harmonics than existing methods.

[0233] The two modulation techniques described further reduce harmonics when the communication or control speed imposes a limit on how close the step voltage output approaches an ideal AC sine wave. In summary, embodiments of the invention increase resolution without altering the control speed; therefore, they can help improve output quality if communication is slow, without necessarily increasing communication speed.

[0234] Figure 6 The output voltage waveform of the present invention is also shown in comparison to prior art waveforms that can be observed at the output of a reconfigurable battery system. In multilevel inverters, the voltage output of the battery cell is typically not a pure sine wave, but rather includes harmonic distortion that can cause problems in the load the inverter is driving. Problems caused by harmonics include increased electromagnetic interference (EMI), reduced efficiency, and increased stress on power semiconductor devices and other components. To mitigate these problems, filters are typically used to smooth the output waveform and reduce the level of harmonic distortion. Harmonic distortion is reduced by a closer fit to the ideal AC waveform.

[0235] Harmonics in multilevel inverters are caused by the high-frequency switching of the power semiconductor devices used to generate the output voltage waveform. In a multilevel inverter, the output voltage is typically synthesized from a series of voltage levels, each generated by a separate set of power semiconductor devices. These devices are switched on and off at high frequencies to create a desired voltage waveform that can contain a significant amount of harmonics.

[0236] High-frequency switching in power semiconductor devices generates harmonics in several ways. First, the switching action produces a square-wave voltage waveform with abrupt transitions containing high-frequency components, including odd and even harmonics. Second, the output voltage waveform is typically not a pure sine wave, which also contributes to harmonic generation. Here, a better "fit" to a pure sine wave reduces harmonics by closely matching the waveform to a pure sine wave.

[0237] Another benefit stemming from the higher voltage resolution derived from modulation is that fully charging the battery pack, especially at high currents, is more accurate and potentially faster, as observed in fast charging or EV acceleration applications. For example, in high-current applications such as fast charging or EV acceleration, cell charging or discharging inherently leads to significant erroneous measurements or inaccurate estimates of parameters such as voltage or SoC level due to the high cell impedance causing potentials that result in such errors. Voltage overpotentials affect battery performance by reducing battery efficiency, meaning the battery's actual voltage output is lower than its theoretical or nominal voltage. These errors take time to correct, and therefore the system takes longer to hit the accurate SoC target during overcharging and overcorrection—for example, when attempting to fully charge an EV battery to 100% capacity / SoC. This becomes particularly problematic when charging damages the battery due to overcharging. Overcharging and over-discharging are both detrimental to batteries, especially lithium-ion batteries. They can reduce battery life, damage battery components, and create safety hazards. However, overcharging is generally considered worse than over-discharging because it can cause more severe damage to battery cells, such as plating, gas generation, thermal runaway, and even fire or explosion. More precise balancing is possible by modulating the contribution of cells and by allowing lower-ranked cells (when ranked partially or entirely based on voltage or SoC) to be used for lower-ranked cells. This results in fewer errors and thus improves battery performance, lifespan, and safety, while potentially increasing speed or enabling EV batteries to be charged to 100% while minimizing damage caused by overcharging.

[0238] Precise balancing is possible because smaller step sizes and therefore, more effectively lower loads on lower-ranked cells, involve less overshoot and less SoC estimation error (or voltage measurement error). For relatively high specified balancing accuracy requirements (such as all cells balancing within 10% or 5% of each other), balancing can be achieved more quickly.

[0239] Another benefit is that, given slow communication or control speeds, this modulation allows for the allocation of duty cycles between 0% and 100%. Modulation also allows for the assignment of different duty cycles to cells of different ranks. Furthermore, the combination of modulation and the application of different duty cycles to different cells allows for ranked distributed gate drive communication schemes to achieve better harmonic reduction than existing methods. Harmonics are further reduced when the communication or control speed imposes limitations on how closely the progressively increasing voltage output approaches an ideal AC sine wave.

[0240] In time-varying waveforms, there exist waveform portions close to zero. These portions can be used to unload certain cells and achieve balancing functions (e.g., by using more cells than others in a time-varying voltage). As part of a ranking-based distributed gate drive communication scheme, some cells are used more than others by assigning different durations to different cells that contribute to different portions of the sine wave.

[0241] Figure 7 The diagram illustrates the contributions of five battery cells to the generated AC waveform, with cell one contributing the longest duration and cell five contributing the shortest duration. Therefore, in some embodiments, the controller is configured to determine the cell voltage and rank cells with higher voltages higher, such that their contributions are greater than those of lower-ranked cells. Since higher-ranked cells are used for longer durations, they will be depleted faster than other cells, and thus those cells with higher voltages will be depleted more than those with lower voltages. Therefore, by ranking the cells according to their voltage so that they converge toward a cell balance target voltage, a cell balance target voltage can be achieved.

[0242] In some embodiments, the reconfigurable battery system described above is part of an electric vehicle (EV). For example, the battery system is the main power source for at least one electric motor of the EV. The EV has a motor controller configured to determine motor demand data. In some embodiments, the battery controller is configured to receive motor demand data from the motor controller and determine a voltage target for the reconfigurable battery based on the demand data, thereby determining the output voltage of the circuit module. In some embodiments, the controller is configured to compare the demand with one or more cell data parameters and to control the series connection of selected cells and the modulation contribution of some of those selected cells based on the motor demand data. For example, for low motor torque demand, the controller may be configured to select ranked cells based on data indicating poor performance. For high motor torque demand, the controller may be configured to select ranked cells based on data indicating good performance. Furthermore, in each case, the controller is configured to apply modulation to the switching circuitry of one or more cells, which reduces the contribution of the low-ranked cells selected in high motor torque demand applications. Cell contributions can be controlled by modulation so that problems such as overheating or low capacity of poor cell performance are mitigated. High motor torque applications are defined as those applications that require all or at least half of the battery cells from which they may be connected to the motor to meet the motor's requirements. Low motor torque applications are defined as those applications that require at least half of the battery cells from which they may be connected to the motor to meet the motor's requirements.

[0243] In some embodiments, the reconfigurable battery system described above is part of an EV charging system. This charging system includes one or more charger connection points, each configured to connect to an electric vehicle. In one embodiment, the reconfigurable battery system is contained within the EV. In another embodiment, the reconfigurable battery system is contained within a charger infrastructure. In yet another embodiment, each of the charging system and the EV contains a separate reconfigurable battery system. In yet another embodiment, each of the charging system and the EV contains an integrated reconfigurable battery system, with some cells contained within the EV and some cells contained within the charging system, and one or more controllers are present, configured to manage one or more of the reconfigurable battery systems, including cell modulation. In these embodiments, the charging controller is configured to receive a signal containing charging request data from an electric vehicle connected to a charger connection point. The charging controller is configured to determine the circuit module output voltage based on the charging request data. Therefore, the target output voltage is achieved by using cell contributions based on variations in cell state modulation as described elsewhere.

[0244] Based on the foregoing, it will be understood that while specific embodiments have been described herein for illustrative purposes, various modifications may be made without departing from the spirit and scope of the invention. Therefore, the invention is not limited except by the appended claims and the elements set forth therein. Furthermore, while certain aspects of the invention are presented hereinafter in certain claims, the inventors contemplate all aspects of the invention in any form of claim that may be used.

Claims

1. A battery control system, comprising: The circuit module includes a pair of output terminals, and the circuit module includes: Multiple cell modules, wherein the multiple cell modules are selectively connected to the output terminal in a series configuration to provide a target output voltage at the output terminal, each cell module comprising: At least one battery cell; A switching circuit configured to operate selectively in two or more states, the states including: The state in which at least one cell is disconnected from the series string; and The state in which at least one battery cell is connected in series with the series string; and A controller configured to provide the target output voltage based on selective control of the operating state of each switching circuit for each cell.

2. The system according to claim 1, wherein, The controller is configured to: The switching circuit of one or more battery cell modules is controlled by a combination of the following methods to meet the output voltage of the target circuit module: Connect one or more battery cell modules in series with the output terminal; and The state of the switching circuit at at least one cell module is modulated relative to the series connection of the one or more cell modules, so that the target voltage is substantially provided at the output terminal of the circuit module.

3. The system according to claim 1 or 2, wherein, The controller is configured to: Determine a set of battery cell modules for series connection to meet the target output voltage within a predetermined time increment; and The switching circuit for controlling the one or more battery cell modules includes a combination of the following: Connect one or more battery cell modules in series with the output terminal, and The switching state of the at least one cell module is modulated within the predetermined time increment so that the output voltage is substantially provided at the output terminal of the circuit module.

4. The system according to claim 2 or 3, wherein, The controller is further configured to: determine the output voltage of the target circuit module, and control the modulation duty cycle of the modulation of the switching state of the at least one cell module based on the output voltage of the target circuit module.

5. The system according to any one of claims 2-4, wherein, The target voltage is defined by the amplitude and phase that vary over time, and the controller is configured to control the series connection of the one or more cell modules at predetermined time intervals and to control the modulation of the switching state over time based on the amplitude and phase that vary over time.

6. The system according to any one of claims 1-5, wherein, The controller is further configured to: Based on determined cell data for each of at least one cell in each cell module, the cell data includes one or more of the following: voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in series arrangement, health status, charging current capability, and discharging current capability. The ranking of each cell module is determined based on the determined cell data; as well as The switching status of the one or more battery cell modules is controlled based on the determined ranking of the one or more battery cell modules.

7. The system according to claim 6, wherein, The controller is further configured to determine the ranking of each cell module based on a weighted combination of two or more determined cell data parameters.

8. The system according to claim 6 or 7, wherein, The controller is further configured to control the modulation duty cycle based on the determined ranking.

9. The system according to claim 8, wherein, The controller is further configured to: determine the output voltage of the target circuit module, and based on the determined ranking of each cell module, preferentially allocate the higher modulation duty cycle of the switching state to those cell modules with higher rankings and / or preferentially allocate the lower modulation duty cycle of the switching state to those cell modules with lower rankings.

10. The system according to any one of claims 6-9, wherein, The controller is further configured to: determine the output voltage of the target circuit module and control the modulation duty cycle of the switching state of two or more cell modules to satisfy the target output voltage.

11. The system according to any one of claims 6-10, wherein, The controller is further configured to: Determine the output voltage of the target circuit module; A weighting factor is determined based on the established ranking, and the weighting factor assigns a modulation duty cycle priority to each cell module; and The modulation duty cycle of the switching state of each ranked cell module is controlled based on the weighting factor.

12. The system according to claim 11, wherein, The weighting factor defines a uniform distribution across the ranked cell modules.

13. The system according to claim 11 or 12, wherein, The weighting factor defines a nonlinear distribution across the ranked cell modules.

14. The system according to any one of claims 1-13, wherein, The controller is configured to: Determine a weighting factor, wherein the weighting factor is a cell contribution value assigned to one or more cells; Determine the number of battery cells to be connected to meet the target output voltage; The switching circuit controlling each cell module includes a combination of the following: Connect one or more battery cell modules in series with the output terminal, and The switching state of the at least one cell module is modulated based on the weighting factor so that the output voltage is substantially provided at the output terminal of the circuit module; New weighting factors are determined based on cell data and / or cell rankings; as well as Determine the number of new battery cells to be connected to meet the target output voltage; as well as Based on the number of new battery cells, the switching circuit of each battery cell module is controlled such that the output voltage is substantially provided at the output terminal of the circuit module.

15. The system according to any one of claims 4-14, wherein, The controller is configured to: Determine the target balance voltage for each cell module, and Identify one or more cell modules with voltages higher than the target voltage for balancing the cell modules, and based on the identified one or more cell modules: The switching state of the identified battery cell modules is controlled by using a higher modulation duty cycle than that of the unidentified battery cell modules.

16. The system according to any one of claims 4-15, wherein, The controller is configured to determine the difference between the following: The combined voltage of the one or more battery cell modules, and the target output voltage; then, for the switching circuit of the at least one battery cell module, The modulation duty cycle is controlled based on the determined voltage difference.

17. The system according to any one of claims 4-16, wherein, The controller is further configured to: Determine the output voltage of the target circuit module. Determine the output voltage. Determine the difference between the output voltage and the target voltage, and then, based on the difference: The weighting factor is adjusted based on the determined ranking, and the weighting factor assigns a modulation duty cycle priority to each cell module. The modulation duty cycle of the switching state of each ranked cell module is controlled based on the weighting factor.

18. The system according to claim 17, wherein, The controller is further configured to: Determine the output voltage of the target circuit module; Based on the determined ranking, the weighting factor is mapped to the modulation duty cycle priority of each cell module; and The modulation duty cycle of the switching state of each ranked cell module is controlled based on the weighting factor.

19. The system according to any one of claims 4-18, wherein, The controller is further configured for each modulated cell: Determine the degree of difference between the current battery cell module ranking and the new battery cell module ranking; as well as The modulation duty cycle of the switching state of each ranked cell module is adjusted based on the difference.

20. The system according to any one of claims 4-19, wherein, The controller is further configured for each modulated cell: Determine one or more cell parameters, including voltage, state of charge, temperature, age, measured lifespan, predicted lifespan, rate of temperature change, internal resistance, position in series arrangement, health status of each cell module, charging current capability, and discharging current capability. as well as Based on one or more determined cell parameters, the modulation duty cycle of the switching state of each ranked cell module is adjusted.

21. The system according to any one of claims 4-20, wherein, The controller is further configured to: Measure the voltage output from the battery cell module, and The modulation duty cycle applied to any one or more battery cell modules is adjusted based on the measured output voltage of the battery cell modules.

22. The system according to any one of claims 1-21, wherein, The controller includes two or more cell processors, each cell processor being configured to control a subset of the modules of the system, and each cell processor being configured to: Determine the cell data of one or more cells under the control of each cell processor; The determined cell data is transmitted to one or more other cell processors; as well as In this configuration, at least one cell processor is configured to determine the ranking of each cell based on the transmitted and determined cell data, and The ranking is then transmitted to one or more other cell processors.

23. The system according to any one of claims 1-22, wherein, The system includes two or more cell processors, each cell processor being configured to: Determine the cell data of one or more cells under the control of each cell processor; The determined cell data is transmitted to one or more other cell processors; as well as Each cell processor is configured to determine the ranking of each cell based on the transmitted and determined cell data; as well as Each cell processor is configured to operate the corresponding switching circuit based on the determined ranking.

24. The system according to any one of claims 1-23, wherein, The controller includes: One or more cell processors, operatively configured to control the switching states of the one or more cell modules, and CPU; The central processing unit and one or more cell processors are configured to communicate via a first communication channel.

25. The system according to claim 24, wherein, The first communication channel includes a channel suitable for transmitting the following: Synchronization signal; Target voltage data; and / or Ranking data, which includes the number of cells ranked that contribute to the target output voltage.

26. The system according to claim 24 or 25, wherein, The communication channel between the central processing unit and the cell processor includes an update frequency lower than the modulation base frequency.

27. The system according to any one of claims 24-26, wherein, Each of the one or more cell processors is configured to communicate with one or more other cell processors via a second communication channel.

28. The system according to any one of claims 24-27, wherein, The one or more cell processors are configured to control the modulation of the switching circuit at a rate higher than the communication rate of the communication channel.

29. The system according to any one of claims 24-28, wherein, The central processing unit is configured to transmit the target voltage to one or more cell processors, and in response, each cell processor is configured to control the state and / or modulation of one or more of its cell modules.

30. The system according to any one of claims 24-29, wherein, The central processing unit is configured to update the target voltage or the ranked cell contribution at a first frequency, and the modulation base frequency is faster than the time increment.

31. The system according to any one of claims 24-30, wherein, The central processing unit is configured to send a synchronization signal operable to control the timing of the switching circuit and thereby target a new output voltage, and one or more cell processors are configured to control the switching state of the switching circuit upon receiving the synchronization signal.

32. The system according to any one of claims 24-31, wherein, The system further includes a low-pass filter connected between the cell module string and the output terminal.

33. An electric vehicle comprising the system according to any one of claims 1-32, the vehicle including a motor controller configured to determine motor demand data; and wherein, The controller is configured to determine the output voltage of the circuit module based on the motor demand data.

34. An electric vehicle charging system, comprising the system according to any one of claims 1-32, wherein the charging system comprises: One or more charger connection points, each configured to connect to an electric vehicle; A charging controller configured to receive a signal containing charging request data of an electric vehicle connected to a charger connection point; as well as The controller is configured to determine the output voltage of the circuit module based on the charging requirement data.

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