Reconfigurable battery system with improved EMC control

Abstract

A system for controlling common mode energy emissions in a reconfigurable battery system is disclosed. The system includes a plurality of battery cell modules arranged in a predetermined geometric arrangement, a switching circuit having a plurality of switches configured to selectively connect or bypass individual battery cell modules from a series connection, and a controller operatively coupled to the switching circuit. The controller is configured to determine a node profile based on position information associated with the geometric arrangement of the battery cell modules, determine a timing profile defining one or more time intervals for switching events, and operate the switching circuit to selectively connect or bypass one or more battery cell modules in accordance with the node profile and the timing profile. By coordinating switching operations as a function of spatial and temporal characteristics of the battery system, the controller controls a common mode energy emission profile of the system.

Description

[0001] Reconfigurable battery system with improved EMC control

[0002] Technical Field

[0003] The invention generally relates to energy storage systems, and in particular to a system configured for improved EMC control.

[0004] Background

[0005] Electromagnetic compatibility (EMC) emissions in a reconfigurable battery system are a considerable source of unwanted noise, especially when switching elements cause common-mode currents to radiate from the system. Managing these emissions effectively requires a combination of design strategies.

[0006] Placing capacitors, often Y-capacitors, between the terminals and ground can absorb common-mode currents before they radiate. This helps mitigate noise but increases "touch current," the current that can pass through a person if they come into contact with a live circuit component, potentially raising the risk of electric shock. This risk is especially pronounced in unbalanced three-phase systems, where load asymmetries can lead to uneven voltage distribution and a higher likelihood of stray currents. There is therefore a limit to the amount of capacitance that can be effectively used.

[0007] Due to safety standards, the capacitance placed between power lines and ground must be carefully managed to maintain safe levels of touch current while still providing adequate noise suppression. Physical shielding around switching elements and strategic placement of ground planes can further control emissions by limiting the propagation of radiated noise. However, metal components increase bulk and costs, and may not be practical in some instances.

[0008] Common-mode chokes can be placed in series with line-neutral signals to suppress noise flowing to ground. Although effective, these chokes must use multiple turns around a core to achieve the necessary high impedance, making them costly, bulky in high-current applications, and a source of significant heat.

[0009] To provide broad-spectrum noise attenuation, a variety of bulky filter components are employed for frequency-specific filtering. However, due to production tolerances, this attenuation cannot always be finely tuned to specific harmonics, which limits effectiveness against narrow frequency bands (e.g., radio frequencies or parasitic resonances). Implementing additional high-Q filters could improve attenuation for specific frequencies but can add complexity, introduce more safety considerations, and increase system heat.

[0010] The power loss in these filters is notable, especially in high-voltage and high-current applications, where inefficiency can lead to considerable heat generation and decreased overall system performance.

[0011] Summary of the invention

[0012] It is object of the invention to alleviate or improve upon the disadvantages of the prior art or at least provide the public with a useful choice. Other objects will be apparent to those skilled in the art.

[0013] In an aspect the invention relates to a method for controlling common mode energy emissions in a reconfigurable battery system, the system comprising a plurality of battery cell modules arranged in a predetermined geometric arrangement and a switching circuit, the method comprising: determining a node profile based on position information associated with the geometric arrangement of the battery cell modules; determining a timing profile defining a time interval for switching events; and operating the switching circuit to selectively connect or bypass one or more of the battery cell modules based on the node profile and the timing profile to control a common mode energy emission profile of the system.

[0014] In an aspect the invention relates to a controller for a reconfigurable battery system... the controller comprising a processor and a memory, the memory storing instructions that, when executed by the processor, cause the controllerto perform the method of determining a node profile based on position information associated with the geometric arrangement of the battery cell modules; determining a timing profile defining a time interval for switching events; and operating the switching circuit to selectively connect or bypass one or more of the battery cell modules based on the node profile and the timing profile to control a common mode energy emission profile of the system.

[0015] In an aspect the invention relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of determining a node profile based on position information associated with the geometric arrangement of the battery cell modules; determining a timing profile defining a time interval for switching events; and operating the switching circuit to selectively connect or bypass one or more of the battery cell modules based on the node profile and the timing profile to control a common mode energy emission profile of the system.

[0016] In an aspect the invention relates to a system for managing common mode energy emissions in a battery system, comprising: a plurality of battery cell modules arranged in a predetermined geometric configuration and selectively connectable in series with supply terminals; a switching circuit including a plurality of switches, each configured to selectively include or exclude a battery cell module in the series configuration relative to the supply terminals; and a controller configured to operate the switching circuit to control the battery cell modules connected in the series configuration, wherein the controller: determines a node profile based on positional information of the battery cell modules in the geometric configuration, and executes switching events according to a timing profile and the node profile, the timing profile defining time intervals for the operation of one or more switches, and the node profile influencing the sequence or selection of switching events, to control a predetermined common mode energy emission profile.

[0017] In an aspect the invention relates to a system for managing common mode energy emissions in a battery system, comprising: a plurality of battery cell modules arranged in a predetermined geometric configuration and selectively connectable in series with supply terminals; a switching circuit including a plurality of switches, each configured to selectively include or exclude a battery cell module in the series configuration relative to the supply terminals; and a controller configured to operate the switching circuit to control the battery cell modules connected in the series configuration, wherein the controller: determines a node profile based on positional information of the battery cell modules in the geometric configuration, and executes switching events according to a timing profile, the timing profile defining time intervals for the operation of one or more switches, to control a predetermined common mode energy emission profile.

[0018] In an aspect the invention relates to a system for controlling common mode energy emissions in a battery system, comprising: a plurality of battery cell modules configured to connect in series to supply terminals, arranged in a predetermined geometric configuration; a switching circuit comprising a plurality of switches, each configured to selectively connect or bypass an individual battery cell module with respect to the series configuration of other cell modules and the supply terminals; and a controller configured to: receive position information of battery cell modules to define a node profile, and operate the switching circuit based on the node profile and a timing profile, wherein the timing profile specifies intervals for switching events to elicit a predetermined common mode energy emission profile characterised by reduced electromagnetic interference within a specified frequency range.

[0019] In an aspect the invention relates to a system for controlling common mode energy emissions in a battery system comprising: a plurality of battery cell modules selectively connectable in series with supply terminals and arranged in a predetermined geometric arrangement; a switching circuit comprising switches configured to selectively connect or bypass a battery cell module in or out of a series configuration with one or more other cell modules and the supply terminals; and a controller configured to selectively operate the switching circuit to control the battery modules connected in the series configuration and elicit a predetermined common mode energy emission profile based on: a node profile based on position information of battery cell modules, and a timing profile defining a time interval for a switching event of one or more switches of the switching circuit.

[0020] In some embodiments, the common mode energy emission profile comprises a common mode spectral noise profile. In some embodiments, the common mode energy emission profile comprises the location of one or more spectral notches or harmonics. In some embodiments, the node profile defines the frequency of at least one spectral notch in the common mode spectral noise profile. In some embodiments, the timing profile defines the spectral spacing of one or more predetermined spectral nulls in the common mode energy emission profile. In some embodiments, the node profile and the timing profile are based on the location of one or more predetermined spectral notches or one or more spectral harmonics.

[0021] In some embodiments, the system comprises a geometric arrangement of battery modules located within a supporting structure, the structure configured to physically support the geometric arrangement. In some embodiments, the position information is indicative of the physical location of the battery modules in the geometric arrangement.

[0022] In some embodiments, nodes are defined by any one or more of: a connection between two battery cell modules, a connection between a battery cell module and a switch; discrete locations of the switching circuit each comprising a different common mode parasitic capacitance.

[0023] In some embodiments, the node profile comprises node data indicative of a common mode parasitic capacitance of each node. In some embodiments, the node profile comprises positional information of each the plurality of battery modules relative to the supply terminals. In some embodiments, the positional information is indicative of physical separation of the battery modules from the supply terminals. In some embodiments, the common mode spectral noise profile is defined by changes in parasitic capacitance from nodes to an equivalent earth potential. In some embodiments, the node profile defines a combination of switching devices having a balanced spectral noise profile. In some embodiments, the node profile defines a combination of switching devices having a substantially equal and opposite earth potential.

[0024] In some embodiments, the timing profile defines a time interval between operation of the switching circuit. In some embodiments, operation of the switching circuit comprises a change of switch state for one or more switches. In some embodiments, wherein the timing profile is based on the node profile. In some embodiments, the timing profile comprises timing data relating one or more nodes to a switch timing interval. In some embodiments, the time interval comprises a time tolerance. The timing profile includes a switch state timing interval which changes width of notch and magnitude of resulting spectral notches in the emissions profile.

[0025] In some embodiments, wherein the common mode energy emission profile comprises a common mode spectral noise profile. In some embodiments, the predetermined common mode energy emission profile comprises a predetermined common mode energy emission pattern. In some embodiments, the common mode energy emission profile comprises one or more spectral characteristics including the location of one or more spectral notches or harmonics. In some embodiments, the common mode energy emission profile comprises reduced emissions within a specified frequency range. In some embodiments, the node profile defines the frequency of at least one spectral notch in the common mode spectral noise profile. In some embodiments, the timing profile defines the spectral spacing of one or more predetermined spectral nulls in the common mode energy emission profile.

[0026] In some embodiments, selective operation of the switching circuit based on the node profile defines the location of a first spectral notch, and the timing profile defines at least a second spectral notch based on the first spectral notch. In some embodiments, the system comprises a geometric arrangement of battery modules located within a supporting structure, the structure configured to substantially maintain the geometric arrangement. In some embodiments, the position information is indicative of the physical location of the battery modules in the geometric arrangement. In some embodiments, the physical location of battery modules comprises at least one row and / or at least one column of battery cell modules. In some embodiments, the position information comprises a capacitive coupling potential of each node. In some embodiments, the node profile comprises positional identifiers associated with the physical arrangement of each battery cell module in the predetermined geometric configuration.

[0027] In some embodiments, nodes are defined by any one or more of: a connection between two battery cell modules, a connection between a battery cell module and a switch; and discrete locations of the switching circuit each comprising a different common mode parasitic capacitance to other discrete locations.

[0028] In some embodiments, the node profile comprises node data indicative of a common mode parasitic capacitance of each node. In some embodiments, the node profile comprises positional information of each the plurality of battery modules relative to the supply terminals.

[0029] In some embodiments, the node profile includes data indicating the proximity of each battery cell module to a reference point of the battery system. In some embodiments, wherein the reference point is the neutral, line or earth point. In some embodiments, the positional information is indicative of physical separation of the battery modules from the supply terminals. In some embodiments, the common mode spectral noise profile is defined by changes in parasitic capacitance from nodes to an equivalent earth potential. In some embodiments, wherein the node profile comprises a combination of switching devices having a balanced spectral noise profile. In some embodiments, the node profile comprises a combination of switching devices having a substantially equal and opposite earth potential.

[0030] In some embodiments, the timing profile defines a time interval between operation of the switching circuit. In some embodiments, operation of the switching circuit comprises a change of switch state for one or more switches. In some embodiments, the timing profile is based on the node profile. In some embodiments, the timing profile comprises timing data relating one or more nodes to a switch timing interval. In some embodiments, the time interval comprises a time tolerance period. In some embodiments, the node profile and the timing profile are updated in real time based on feedback from sensors monitoring the common mode energy emissions. In some embodiments, the timing profile is configured to adjust the width of a spectral notch in the common mode energy emission profile by varying the duration of switching intervals and thereby the time between each operation of the switching circuit. In some embodiments, the width of the notch in the common mode energy emission profile is based on the time tolerance period set by the controller. In some embodiments, the controller is configured to control each operation of the switching circuit within the time tolerance period based on distribution of switching events within the period overtime. In some embodiments, the controller dynamically alters the magnitude of the spectral notch by adjusting the timing profile to control the overlap of switching events. In some embodiments, the timing profile positions a harmonic in the common mode energy emission spectrum at a predetermined frequency to mitigate interference with external systems. In some embodiments, the predetermined frequency aligns with a known problematic frequency range detected in the operating environment. In some embodiments, the timing profile is pre-programmed with frequency maps corresponding to interference-prone zones, allowing the controller to position harmonics dynamically.

[0031] In some embodiments, the controller is further configured to operate the switching circuit to control the series connection of battery modules to meet a time varying target output voltage. In some embodiments, wherein the target output voltage comprises a voltage tolerance; and the controller is configured to selectively connect or bypass a battery cell module in or out of a series configuration with one or more other cell modules and the supply terminals to provide the target output voltage within the voltage tolerance. In some embodiments, wherein the switching circuit is configured to include a battery cell module in the series connection by: the connection of one or more switching devices that connect the battery cell module in series with another battery cell module and the supply terminals, and the disconnection of one or more switching devices configured to form a parallel current path around the battery cell module. In some embodiments, wherein the switching circuit is configured to bypass a battery cell module from the series connection by: the disconnection of one or more switching devices that connect the battery cell module in series with another battery cell module and the supply terminals, and the connection of one or more switching devices configured to form a parallel current path to the battery cell module.

[0032] In some embodiments, the controller is configured to execute switching events according to the timing profile and the node profile, whereby the timing profile comprises time intervals for the operation of one or more switches, and the node profile comprises a sequence or selection of switching events, to generate the predetermined common mode energy emission pattern. In some embodiments, the controller is configured to assign a priority order to the switching events based on positional identifiers in the node profile. In some embodiments, the controller uses the timing profile to position a harmonic resonance outside a frequency band associated with sensitive electronic systems. In some embodiments, the system further comprises a current sensor configured to sense the parasitic current caused by operation of the switching circuit. In some embodiments, the controller is configured to determine node profile information based on the sensed parasitic current. In some embodiments, the controller is configured to determine node profile information based on data representing the relative geometric location of each battery module. In some embodiments, the controller is configured to determine whether minimising spectral noise, or controlling a spectral noise notch based on one or more compliance factors, and control the operation of the switching circuit based on that input. In some embodiments, the compliance factor is based on a predetermined emission profile.

[0033] In some embodiments, the controller is configured to selectively operate the switching circuit to control the battery modules connected in the series configuration based on cell selection criteria comprising two or more of: the geometric location of battery cells in the battery system; availability data comprising indicators of one of more of battery module temperature, state of charge, and state of health; and battery module rank data. In some embodiments, the battery module rank data is based on one or more of the geometric locations of battery cells in the battery system, and / or availability data comprising indicators of one or more of battery module temperature, state of charge, and state of health.

[0034] In some embodiments, the controller is configured to: determine the predetermined common mode energy emission profile comprising a target frequency for noise reduction; determine a target voltage to be provided at the supply terminals; identify, based on the node profile, one or more battery cell modules for inclusion or exclusion from the series configuration; operate the switching circuit, based on the timing profile, to include or exclude the identified battery cell module to provide the target voltage and elicit the predetermined common mode energy emission profile.

[0035] In some embodiments, the controller is configured to selectively operate the switching circuit to control the battery modules connected in the series configuration based on cell selection criteria comprising spectral information based on the common mode energy emission profile. In some embodiments, wherein the controller is configured to: determine, based on battery module availability data, two or more battery modules available for connection or disconnection from the series configuration by selective operation of the switching circuit; evaluate the spectral noise for each battery module available for connection or disconnection, and control connection or disconnection of a battery module from the one or more available battery modules determined by the battery module having less spectral emission at a target frequency than another battery module, and / or control connection or disconnection of a battery module from the one or more available battery modules determined by the battery module meeting a target spectral emission.

[0036] In some embodiments, wherein the controller is configured to: determine, based on battery module availability data, two or more battery modules available for connection or disconnection from the series configuration by selective operation of the switching circuit; determine a battery modules is unavailable based on a determination determined to have more spectral emission at a target frequency than another battery module.

[0037] In some embodiments, the controller is configured to: determine two or more battery modules available for connection or disconnection from the series configuration based on battery module availability data; evaluate the spectral noise characteristics of each available battery module; select one of the two or more battery modules for connection or disconnection based on: the battery module exhibiting lower spectral emissions at a target frequency compared to other battery modules, or the battery module meeting a predetermined target spectral emission profile; and exclude, from availability, the battery module determined to exhibit higher spectral emissions at the target frequency than a predefined threshold.

[0038] In some embodiments, the controller is configured to: determine two or more battery modules available for connection or disconnection from the series configuration based on battery module availability data; evaluate the spectral noise characteristics of each available battery module; determine: the battery module exhibiting higher spectral emissions at a target frequency compared to other battery modules, or the battery module not meeting a predetermined target spectral emission profile; and change the connection or disconnection timing interval for the determined battery module. In some embodiments, the controller is further configured to: determine rank data based on the common mode noise of two or more battery modules and operate the switching circuit to control the battery modules connected in the series configuration based on the rank.

[0039] In some embodiments, the controller is further configured to: determine rank data based on the spectral emission at a target frequency for each of two or more battery modules, and, operate the switching circuit to control the battery modules connected in the series configuration based on the rank.

[0040] In some embodiments, the plurality of battery cell modules comprises a sequential layout of Mo to Mxof X plurality of battery cell modules, wherein each battery cell module is associated with a switch group configured to operate the connection or disconnection of the associated battery cell module; and wherein the controller is configured to operate the switch groups associated with battery cell modules Mo+Nto MX-N based on the switch timing profile. In some embodiments, the MO module is arranged adjacent to a first supply terminal and the Mx module is arranged adjacent to a second supply terminal. In some embodiments, the controller is configured to operate the switch groups simultaneously based on the switch timing profile. In some embodiments, the controller is configured to: receive or determine the common mode noise potential associated with each node voltage step (dv / dt) and parasitic capacitance (C) of each node; and connect or bypass cell modules from the series configuration based on a desired change in unit current. In some embodiments, the desired unit current is based on the EMC profile. In some embodiments, the two or more switch groups comprise a combined EMC profile based on common mode noise potential, operation of a first switch group of a first pair of switch groups at first time, operation of a second switch group of the first pair of switch groups at a second time based on a predetermined time interval corresponding to the predetermined EMC profile.

[0041] In some embodiments, the controller is configured to output switch control signals based on the time tolerance by: controlling the connection or disconnection of a first cell module, then controlling the connection or disconnection of a second cell module based on a switching time interval in accordance with the voltage tolerance and a time tolerance. In some embodiments, the switching time interval is selected based on at least one desired spectral notch in the EMC profile. In some embodiments, the predetermined time interval is determined from one or more target spectral notch frequencies.

[0042] In some embodiments, the plurality of battery cell modules comprises a sequential layout of Mo to Mxbattery cell modules, and wherein the controller is configured to: operate the connection or disconnection of battery cell modules by the quasi-simultaneous operation of Mo+Nto MX-N pairs of switch groups, where N is 0 or more, based on: operation of a first switch group of a first pair of switch groups at first time, operation of a second switch group of the first pair of switch groups at a second time based on the timing profile and the EMC profile.

[0043] In some embodiments, the controller is further configured to operate the switching circuit to meet a time-varying target output voltage. In some embodiments, the predetermined geometric arrangement comprises at least one row of battery cell modules, and wherein the position information comprises data indicating the proximity of each battery cell module relative to one or more supply terminals.

[0044] In some embodiments, the position information is indicative of a common mode parasitic capacitance of each of a plurality of nodes within the switching circuit, each node being associated with a respective battery cell module.

[0045] In some embodiments, the nodes are defined by at least one of: a connection between two battery cell modules, or a connection between a battery cell module and a switch.

[0046] In some embodiments, the common mode energy emission profile comprises a common mode spectral noise profile having one or more spectral characteristics.

[0047] In some embodiments, the controller is configured to operate the switching circuit based on the node profile to define a frequency of at least one spectral notch in the common mode spectral noise profile. In some embodiments, the controller is configured to operate the switching circuit based on the timing profile to define a spectral spacing of one or more harmonics in the common mode spectral noise profile.

[0048] In some embodiments, the timing profile comprises a time tolerance period, and wherein the controller is configured to vary a timing of the switching events within the time tolerance period to adjust a width of the spectral notch.

[0049] In some embodiments, the controller is configured to dynamically alter a magnitude of the spectral notch by adjusting the timing profile to control an overlap of the switching events.

[0050] In some embodiments, the controller is configured to operate the switching circuit by selecting a combination of switches having a balanced spectral noise profile based on the node profile.

[0051] In some embodiments, the controller is configured to select the combination of switches corresponding to battery cell modules at substantially opposite electrical positions within the geometric arrangement to achieve the balanced spectral noise profile.

[0052] In some embodiments, the controller is further configured to select the one or more battery cell modules based on cell selection criteria comprising at least one of: a state of charge (SOC), a state of health (SOH), or a battery module rank.

[0053] In some embodiments, the controller is configured to prioritize the control of the common mode energy emission profile over the cell selection criteria when selecting the one or more battery cell modules.

[0054] In some embodiments, the controller is configured to determine whether to prioritize the control of the common mode energy emission profile or the cell selection criteria based on one or more compliance factors.

[0055] In some embodiments, the controller is further configured to: identify, based on the node profile, one or more battery cell modules for inclusion in or exclusion from the series connection to provide the target output voltage; and operate the switching circuit based on the timing profile to include or exclude the identified battery cell modules and control the common mode energy emission profile. In some embodiments, the controller is configured to execute a sequence of switching events according to the timing profile and the node profile to generate a predetermined common mode energy emission pattern.

[0056] In some embodiments, the system further comprising one or more sensors configured to monitor the common mode energy emissions.

[0057] In some embodiments, the controller is configured to update the node profile and the timing profile in real time based on feedback from the one or more sensors.

[0058] In some embodiments, the one or more sensors comprises a current sensor configured to sense a parasitic current caused by operation of the switching circuit.

[0059] This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0060] Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

[0061] Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

[0062] To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. The term “and / or” referred to in the specification and claim means “and” or “or”, or both. The term “comprising” as used in this specification and claims means “consisting at least in part of”. When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement all need to be present but other features can also be present. Related terms such as “comprise” and “comprised” are to be interpreted in the same manner.

[0063] As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. As used hereinbefore and hereinafter, the term “and / or” means “and” or “or”, or both.

[0064] It is acknowledged that the term “comprise” may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. Forthe purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning, allowing for inclusion of not only the listed components or elements, but also other non-specified components or elements. The terms ‘comprises’ or ’comprised’ or ‘comprising’ have a similar meaning when used in relation to the system or to one or more steps in a method or process. It will be further understood that the terms “includes,” “comprises,” “including,” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0065] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

[0066] In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally forthe purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, a reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art. It is also to be understood that the specific devices illustrated in the attached drawings and described in the following description are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.

[0067] As used hereinbefore and hereinafter, “(s)” following a noun means the plural and / or singular forms of the noun.

[0068] When used in the claims and unless stated otherwise, the word ‘for’ is to be interpreted to mean only ‘suitable for’, and not for example, specifically ‘adapted’ or ’configured’ forthe purpose that is stated. For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.

[0069] Brief description of the drawings

[0070] The invention can be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the invention. Furthermore, like reference numerals designate corresponding parts throughout the several views.

[0071] Figure 1 shows an exploded view of two exemplary battery modules which each contain two battery cells connected in series.

[0072] Figure 2 shows a circuit representation of the capacitive coupling between the two battery modules and the surrounding metal can structures.

[0073] Figure 3 shows an exemplary control structure.

[0074] Figure 4 shows another exemplary control structure.

[0075] Figure 5 shows an exemplary circuit of a simplified reconfigurable battery system.

[0076] Figure 6(A) shows an example simulation of a time varying voltage target.

[0077] Figure 6(B) shows the common mode current flow l(R24) to earth.

[0078] Figure 7(A) shows another example simulation of a time varying voltage target.

[0079] Figure 7(B) shows another common mode current flow l(R24) to earth.

[0080] Figure 8 shows two exemplary and overlaid common mode current spectrums.

[0081] Figure 9 shows a detailed diagram of a battery system indicating nodes where each module contains two series connected battery cells.

[0082] Figure 10 shows a graph of examples of two cell selection algorithms.

[0083] Figure 11 shows the resulting noise spectrum of the common mode current for each of the two exemplary cell selection algorithms. Figure 12 shows a graph of the current spectrum showing the magnitude of the spectral noise notches which are created.

[0084] Figure 13 shows an exemplary reconfigurable battery system layout with switches configured forthe connection or bypass of individual cell modules with a series configuration of cells.

[0085] Figure 14 shows another exemplary reconfigurable battery system layout which allows limited connection and bypass of cell modules in the circuit.

[0086] Figure 15 shows another exemplary reconfigurable battery system layout with switches configured for the connection or bypass of individual cell modules with a series configuration of cells.

[0087] Figure 16 shows another exemplary reconfigurable battery system layout with switches configured for the connection or bypass of individual cell modules with a series configuration of cells.

[0088] Description

[0089] Embodiments of the present disclosure are now described. Exemplary methods, devices, assemblies and systems are described herein. 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 preferred or advantageous over other embodiments or features. More generally, the embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0090] In this specification, the terms “energy storage module”, "battery cell unit", "cell unit" or “cell module” are generally intended to refer to a module which can store an electrical charge and can refer to an individual battery cell or multiple battery cells connected in series, parallel, or a combination of series and parallel. Where the terms battery cell, cell or cell unit is used, equally applicable are battery module, module, cell module or module unit, where a module may contain one or more cells in series and / or in parallel. An energy storage module may also include circuit components such as fuses, resistors, passively controlled diodes, capacitors or inductors that are connected in series and / or parallel with one or more cells.

[0091] In some embodiments, an energy storage module may be designed to include one or more units enabling a charge capacity of at least 10Ah, 20Ah 40Ah, 60Ah, 100Ah, 200Ah, or 400Ah ampere hours. In some embodiments, a plurality of energy storage units may comprise a first and a second energy storage unit, with the first energy storage unit having a charge capacity that is substantially larger than the charge capacity of the second energy storage unit.

[0092] Reconfigurable battery system

[0093] Embodiments of the invention discussed in this specification relate to a battery control system comprising a circuit module comprising a pair of supply terminals configured to provide a target supply voltage from series connected battery cell modules. The term supply terminals refers to a first and a second terminal which form part of a current path between one or more battery modules and a load. The supply terminals can comprise a terminal where current can flow in, a terminal where current can flow out, or both terminals may function as terminals where current can flow in and out based on the polarity configuration of the battery cell modules.

[0094] The circuit module comprises a circuit configurable to selectively connect cell modules in series by the connection of bypass of one or more cells with one or more other cells and the supply terminals. The circuit is selectively controlled by a controller apparatus such as one or more processing devices. At some times, the circuit is selectively controlled to include one cell in series between the supply terminals to achieve a minimum output voltage, or substantially thereof. Other times the circuit is selectively controlled to include no cells in series between the supply terminals to achieve zero output voltage. The maximum output voltage, or substantially thereof, at the supply terminals is achieved by including all series-connectable cells in series with the supply terminals.

[0095] A reconfigurable battery system is a system which includes such a circuit module and control apparatus. A cell module typically comprises 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 thereby bypassing the at least one cell, or connect the at least one cell between the first terminal and the second terminal thereby including the cell in a series connection.

[0096] A cell module may contain any number of cells in series, or parallel, or a combination of series and parallel, and the switching circuit controls the at least the series connection of any one of those cells to the cell terminals. For example, in a reconfigurable battery system it is common for the switching circuit to control the connection of those cells to the terminals or for the terminals to be connected such that the cells are bypassed. Other cell configurations are possible and may be facilitated by a switching circuit configuration which is designed to reverse the polarity of cells within the cell module. Polarity control may be provided by, for example, an H-Bridge or 2n+2 inverted H-Bridge circuit topologies.

[0097] Circuits for supporting cells and the arrangement of switches for controlling connected or bypassed states of cells can have many configurations. In some embodiments, the cells and associated switching circuit have a fixed number of switches, such as two, for each cell. However, in other embodiments, the switching circuit may have combinations of two or more switches which are configured to operate to connect or bypass a cell.

[0098] Many examples of switching circuits of a reconfigurable battery system are shown in US patent 12,062,815.

[0099] Controller

[0100] The term “controller” or “control apparatus” as used in this specification will most commonly be used to describe the functions of one or more processing devices such as microprocessors. A controller may be a single processor, or a combination of multiple processing devices as may be practical. A controller will typically feature output pins which are operably connected to switching devices to control the state of that switching device. For example, the pin of a microprocessor may be connected to operate the gate of a MOSFET switching device. Another pin of a microprocessor may be connected to measure a voltage from a sensor. In some embodiments, there is a controller configured to control functionality of the system such as the determination of a target voltage, and the output signals required to operate the switching circuit of one or multiple cell modules to generate the target supply voltage.

[0101] In some embodiments, the supply voltage output from the battery system is determined by a plurality of controllers operating to control specific switches which need to be connected in order to connect a number of cells to achieve a target voltage. The target supply voltage will typically be predetermined on the basis of the supply output voltage requirement for the system. For example, in some embodiments, the system is configured to generate a mains voltage which may be a sinusoidal 110 to 240V signal at 50 to 60Hz. Other examples include DC voltage applications such as would be found in an electric vehicle (EV), EV charging device, or other more general DC application. As such, the target supply voltage may be time varying or time static. A battery system is most often found with lithium-based cells and as such the cell voltage is typically operated between 2.5 and 4.2V per cell.

[0102] In some embodiments, there are multiple controllers configured to control groups of switching devices which are each configured to control the connection of one or more cells. These controllers are referred to as cell controllers. In such embodiments, cell controllers are each connected to one or more switches and figured to control the switches in order to connect any specific one or more cells in order to meet the target supply voltage. In some embodiments, each cell controller operates under the control of a master controller which, for example, is configured to send a target supply voltage requirement to the cell controllers which in turn interpret that requirement and determine whether to source current from cells under its control. The master cell controller may be referred to as a central stack controller. In other embodiments, the cell controllers operate together based on an algorithm which controls or determines the connection of cells. Various other control techniques are possible which operate cell controllers, connect or bypass cells and achieve a target supply voltage.

[0103] The cell controllers are local controllers configured to operate switches of a local switching circuit. Accordingly, in some embodiments, the reconfigurable battery system contains many cell controllers, where each cell controller is configured to operate one local switch circuit.

[0104] Each cell controller is typically tasked with operating switches in its local switch group based on a target supply voltage of the reconfigurable battery system. In some embodiments, the target supply voltage is determined by a master controller which transmits information to each cell controller which is able to be interpreted in order to operate the switches of the switch group at a particular time such that the combined cells switched in the series configuration generates the target supply voltage.

[0105] In some embodiments, a cell controller is typically implemented by a microprocessor device and may optionally include supporting hardware to facilitate the desired functionality of the device such as gate drive electronics.

[0106] Overview of EMC in RBS

[0107] A circuit of a reconfigurable battery system has junctions between switches and cell terminals which define nodes. The nodes are actively switched in and out of a series configuration of battery cell modules in order to meet a time varying target voltage at the system supply terminals. Each node is therefore a discrete circuit location which changes voltage level when a change of state occurs in the switching circuit controlling at least the series configuration of cells. Such emissions are often referred to as electromagnetic compatibility (EMC) emissions and can become a significant source of noise such that system operations are disrupted internally within a system or in an externally connected system. Each switching action creates rapid changes in voltage at the node, which lead to transient signals which can radiate as electromagnetic emissions, primarily due to common-mode capacitive coupling. EMC is caused by nodes which rapidly change in voltage potential to create a transient emission which couples to nearby components or ground planes through parasitic capacitance. The parasitic capacitance between the nodes and ground causes common-mode currents which flow in unison from all nodes toward ground, often radiating as high-frequency electromagnetic interference (EMI) or conduction. Common-mode emissions are particularly pronounced because they can use the circuit wiring, battery enclosures, or connected structures to radiate and conduct unwanted emissions. Therefore, an emission occurs when the potential energy of each node changes. In some embodiments, the emission is controlled to elicit desired emission characteristics such as the magnitude of noise at one or more target frequencies.

[0108] In some circuits, switches define the position of nodes and each switch or pair or combination of switches that causes at least one cell to be bypassed or included is a discrete position. In some circuits, positions are denoted based on their schematic locations in reference to the line / neutral point rather than a physical location - for example, if the cell module is the first to be electrically connected to the line / neutral, then it could be considered to be the first position.

[0109] Switching events of the switching circuit cause a step change in voltage at a node. The magnitude of step change is insignificant and what is most important is the sum of differential voltage of the cells that are included or bypassed in the series configuration due to the switching event. Due to the parasitic capacitance coupling between the nodes and the chassis (ground plane), the step change, in combination with position(s) of switching, lead to a non-zero common mode current spike. The magnitude of the common mode current is directly proportional to the asymmetry of positional switching. For example, if a single switch in the middle position is activated then there is no asymmetry therefore minimal spike. These positional switching combinations, or specific combinations of positions to achieve various voltage output of the battery system define a so-called positional switching profile, or positional switching algorithm.

[0110] The frequency and amplitude of EMC is related to the rate of switching and the circuit layout, including the distance and alignment between switching nodes and ground planes. Higher switching speeds exacerbate emissions due to faster voltage and current changes causing larger transients. EMC causes operational inefficiency, often requiring filtering devices to redirect voltage transients from a signal. EMC may also cause operational signals to be distorted. For example, a reconfigurable battery system has many analogue to digital converters (ADC) tasked with measuring voltages such as cell voltages and currents. Noise at the input of an ADC causes a measurement error. It is therefore highly desirable to ensure that measurement error does not occur or is mitigated by the suppression of any noise at the ADC input. Therefore, in some embodiments, the system is operable to control a lower noise floor, and in other embodiments, the system is operable to control EMC noise such that spectral interference at operational frequencies is lowered or mitigated. In the ADC example, controlling the EMC noise profile to align a spectral null with the sampling frequency of an ADC may be desirable.

[0111] In the frequency domain, each positional switching algorithm defines a frequency spectral profile of the common mode current, leading to predetermined peaks and notches, where notches indicate an attenuation in generated frequencies. This spectral profile can be controlled to attenuate certain frequency ranges, such as ranges at which sensitive equipment, or circuits operate at.

[0112] Positional switching algorithms can be derived mathematically, and exemplary equations are discussed below. Positional switching algorithms are intended to control the common mode current to be low or zero by using cancellation techniques, at least at a desired frequency range as it is not always practical to achieve overall zero noise generation by cancellation.

[0113] In some embodiments, a targeted noise profile includes an average noise profile, indicating that the desired noise performance is a performance over a time period. In some embodiments, the time period is up to 20ms. In some embodiments, the targeted noise profile includes instantaneous noise performance, including the noise associated with a single switching event. Embodiments discussed in this specification relate to, but are not exclusive to, the control of the instantaneous or peak noise. By controlling the peak noise, the average noise is also controlled. In some embodiments, there is a controller configured to control the unwanted buildup of noise in undesirable frequencies. For example, when a first switch event occurs, the controller determines when and what the next switch event to occur is to be for the purposes of creating certain spectral energies.

[0114] FFT can be performed by the controller for the next 20 ms (of a 50 Hz AC waveform) to anticipate any strong harmonics at the current switching frequency using the current switching profile that does not sufficiently attenuate the noise (ground current spikes). When this is identified another switching profile can be selected via some sort of voting mechanism, and the selection of another switching profile can be based on attenuation of noise or another goal can be prioritised such as balancing requirements / SoH / availability and other relevant battery data.

[0115] Structure of exemplary battery module and capacitive coupling to the enclosure

[0116] Figure 1 shows an exploded view of two exemplary battery modules 20, 21 which each contain two battery cells connected in series. A battery module may be one cell, or two or more cells with a combination of series or parallel connected cells. The two battery cell modules may share a common terminal such that they are connected in series and may therefore appear as a single battery cell within the module.

[0117] The exemplary battery modules 20, 21 are separated by a metal plate 11 and the outer surface of each module is covered by a further metal plate 10, 12. Each metal plate 10, 11 , 12 forms part of a cell enclosure, housing or can which at least provides some protection of the cells of the battery module.

[0118] Parasitic capacitance arises from the separation of charge between the surrounding metallic structures, such as the metal can or other cooling plates placed in proximity to, and typically against, the cell, and the active chemical material in a battery cell, such as a cell pouch. A dielectric material typically separates the battery chemicals and surrounding metals such as a plastic material of a cell pouch or other materials provided for electrical isolation or environmental protection.

[0119] Figure 2 shows a circuit representation of the capacitive coupling between the two battery modules 20, 21 and the surrounding metal can structures. Each terminal from the series connected cell pairs or V1 and V2 in can 1 , and V3, V4 from can 2, is coupled by parasitic capacitance to a common earth potential point. Parasitic capacitors C1-C6 represent capacitive coupling between each voltage potential and the common earth through the surrounding metal structure; in this case, the metal cans of each battery module. Common mode current is caused by the voltage derivative across each parasitic capacitor over time.

[0120] The cells in the exemplary module are separated by a metal plate, and the outer sides of the cells are enclosed by additional metal plates. The metal plates provide a metal can enclosure which can provide an environmental shield and heatsink. In other examples, the battery cell module encloses a single battery cell.

[0121] Figure 3 shows an exemplary control structure whereby a controller 45 is operatively coupled to a switching circuit 40 such that the state of each switch in the switching circuit can be controlled and thereby the battery modules 42 which are connected to or bypassed from the series configuration is also controlled.

[0122] Figure 4 shows another exemplary control structure whereby there is control hierarchy based on a central controller 45 providing instructions to any number of module controllers 41 . Each module controller 41 is configured to selectively control a switching circuit 40 operable to selectively control the series connection of battery modules 42. In this example, a central controller is typically configured for the determination of a target supply voltage from each switching circuit or other such high level information, and the module controllers are configured to selectively operate the switching circuit to meet that target supply voltage.

[0123] A further module may be configured to connect the output of each battery module 42a, 42b - 42n in series, or parallel as desired. Any number of battery modules 42 may be provided based on the voltage and current output requirements.

[0124] Figure 5 shows an exemplary circuit of a simplified reconfigurable battery system having any number of battery modules (C1 - C4, but may be of any number) which are configurable in a series configuration to provide an supply voltage by selective configuration of the switching circuit formed by switches S1-Sn.

[0125] The switching circuit has switches configured to selectively connect or bypass a battery cell in or out of a series configuration with one or more other cell modules and the supply terminals based on selective control of which switches are open or closed. The supply voltage may also be polarity controlled by selective operation of the switching circuit to configure the current path and terminals of the battery module connected with each supply terminal 30. The series configuration may include any one or more of the battery cells shown based on a target supply voltage desired at the supply terminals 30. A target supply voltage is provided by closing the combination of switches S1-Sn which create a series current path through one or more cells. For example, by closing switch S1 , S4, S5, S8 and Sn (with other switches remaining open), a supply voltage of the sum of battery modules C1 , C2, C3 and C4 is provided on the circuit supply terminals 30.

[0126] Further, there are exemplary nodes N1-N4 which represent common mode coupling locations of the switching circuit which are subject to sudden voltage potential changes and therefore prone to parasitic coupling as each adjacent switch transitions state. Each node comprises a physical location of the circuit in the arrangement of battery cells, and therefore a relative proximity to the ground plane and supply terminals and may therefore relate to the position of a battery module in a geometrical arrangement, or by the parasitic coupling potential of that circuit location, or by some other data based on the emissions potential of that circuit location.

[0127] As each switch is controlled to transition state, the voltage derivation across the parasitic capacitor creates a current flow. The common mode voltage with respect to earth of the battery modules above and below the switch location are the same. The position of the transitioning switch changes the number of cells which undergo a positive voltage step (are located upstream in the series configuration) or negative voltage step (are located downstream in the series configuration), and therefore creates a current flow to earth based on the number of nodes above and below the transitioning node in the circuit arrangement. The common mode pulse current created by a switch transition and therefore a change in voltage for a node can be represented by:

[0128] [Equation 1] where the NodepOsition total is the total number of nodes defined by the switches, and NodepOsition is the physical position of the switches operated. For example, a middle located node (having equal number of higher and lower nodes) experiences 0 Amp parasitic current since the parasitic capacitance is equalised above and below the position of that node.

[0129] The total common mode current that would flow out into the ground plane as a result of changing the voltage state of nodes would then be represented by:

[0130] [Equation 2 where Nswis the total number of switch position in the system, T is the time of a repetitive switching cycle (time to switch all the switching states), f(cellSseiection) is the ratio of the common mode current in this switching position, CParasitic is the equivalent capacitor between a switching node to the earth potential in the system, dV / dt is the voltage slope of switching node with respect to earth potential, n is the number of switch (0<n<Nsw), f is the switching frequency of each switching event, and t is the time of particular earth current magnitudes and as such is generally at the time of a switching event. As this is a time domain signal, t is shown by the x axis and represents a timeline of switching events. The change of state of a switch therefore causes one or more battery modules in the series configuration, both above and below the switch point, to shift in the common mode voltage with respect to earth. The common mode coupling positional dependency of each battery module can be used to control the common mode current flow into the earth ground plane to thereby manipulate the noise spectrum from the resulting current.

[0131] Exemplary embodiments are described with reference to earth as a common mode reference point. However, line, neutral, or midpoint of line and neutral, or any relevant circuit reference location may provide the common mode reference point. Common mode current or noise therefore refers to the noise or current at the designated reference point of the circuit. The reference point is ideally the earth or neutral line of a system for simplicity in emission analysis. However, the reference point may be any point in a system and a bias is applied to determine emission information and from node profile information. The bias is typically a voltage offset of the reference point relative to the remainder of the system.

[0132] In some embodiments, there is a controller configured to operate the switching circuit based on or within a specific timing interval such that the noise spectrum is manipulated to achieve one or more spectral notches. The frequency of generated spectral notches can be controlled to align with sensitive frequencies within the circuit, such as frequencies with strong noise characteristics to thereby lower those characteristics, or the operating frequency of sensitive electronics such as an analogue to digital converter sampling frequency.

[0133] A controller can analyse the voltages to determine their spectral information using similar techniques such as a Fast Fourier Transform (FFT). It will be appreciated that control operations by the controller take place in the time domain, and the effect of the operations is realised in the frequency domain and specifically the control of a common mode noise magnitude at a target frequency, referred to and demonstrated as a spectral notch. For example, the controller measures or predicts (such as based on SOC data) node voltages which will change over time based on operation of the switching circuit. An FFT algorithm processes the voltage data to separate it into its individual frequency components where the FFT reveals the underlying frequencies present in the voltage signal, including spectral peaks and nulls, and the location of notches.

[0134] If desired, a spectrum showing which frequencies exist in the voltage signal and their respective strengths (amplitudes) can be generated. However, in some embodiments the controller determines only the amplitude of the noise spectrum at a desired frequency. The desired frequency may be input to the controller as data representing an operational frequency of sensitive electronics in the proximity of the battery system. In some embodiments, there is a controller configured to determine spectral information based on changes in node voltages.

[0135] In one exemplary embodiment, the controller performs FFT analysis for the next 20 ms of a predetermined time varying voltage target, such as a mains waveform of 50 Hz or 60 Hz AC, to identify any undesirable harmonics or other spectral content at the current switching frequency using the current switching profile that does not sufficiently attenuate the emissions noise. When undesirable spectral content is identified, another switching profile can be selected, and the selection of another switching profile can be based on attenuation of noise or another goal can be prioritised such as balancing requirements, SoH, or other battery module availability considerations.

[0136] For a particular target frequency (f) where a notch is desired, and a range of switching frequencies (Fsw / Nsw), a selection algorithm can be designed as follows:

[0137] [Equation 3] where Im is the imaginary number of the equation, Nswis the total number of switch positions in the system, T is the time of a repetitive switching cycle (time to switch all the switching positions). An equation to define the cell selection algorithm is discussed further below, where f(cellsseiection) is the ratio of the common mode current in this switching position. Equation 3 sets the imaginary component of the spectral energy at a target frequency f to zero. To derive the cell selection algorithm, f(Cellselection), the controller can utilise numerical methods to solve this equation for a set of switching coefficients that satisfy this condition. This process identifies the specific combination and sequence of cell switching events required to create the desired spectral notch at the target frequency f.

[0138] Figure 6(A) shows an example simulation of a circuit where numerous cells are connectable in series over time to step the supply voltage to meet a time varying target. In this example, the supply voltage V(out) is stepped from OV to about 130V in 11 steps, then back down to 0V in 11 further steps. The step timing interval is about 1 mS. In this example, the switches are closed from one end adjacent to a first supply terminal to the other end adjacent to an opposite supply terminal in the exemplary circuit shown by Figure 4.

[0139] Figure 6(B) shows the common mode current flow l(R24) to earth caused by each of the voltage steps where it is observable that the end cells are subject to stronger current pulses due to their position in the sequence. The middle node experiences no parasitic current due to the equal number of higher and lower nodes in the sequence.

[0140] Notable from the positive-going section is the first and last voltage steps are of a smaller voltage and therefore have a smaller current. This may be controlled by the number of cells connected in series at the same time, and the state of charge of a connected cell.

[0141] Figure 7(A) shows an example simulation of the same circuit where numerous cells are connectable in series over time to step the supply voltage to meet a time varying target. In this example, the supply voltage V(out) is stepped from 0V to about 130V in 6 steps, then back down to 0V in 6 further steps. The step timing interval is around 2mS. Here, battery modules are connected based on approximately similar proximity to the supply terminals in the arrangement such that each end battery module is connected at the same time, then the next inward from the respective supply terminals, and so on. The relative proximity of each battery module to the nearest supply terminal means an approximately similar and opposite magnitude of parasitic capacitive coupling.

[0142] For example, sequential layout of Mo to Mx of X battery cell modules, each associated with switches configured to operate the connection or disconnection of the associated battery cell module, are controlled based on the substantially simultaneous connection of switches associated with battery cell modules Mo+Nto in N steps. Here, the Mo module represents the battery module which is arranged adjacent to a first supply terminal and the Mx module is arranged adjacent to a second supply terminal such that substantially equal and opposite parasitic current is experienced by the node under transition.

[0143] Figure 7(B) shows the common mode current flow to earth caused by each of the voltage steps where it is observable that substantial balancing current causes the total current to be substantially nullified. As a result, the EMC output from the system is minimised.

[0144] It should be noted that switching two battery modules into the series configuration simultaneously means that the voltage step is higher at the transition than if one battery module were to be switched. For this reason, it may be desirable to switch pairs of battery modules in or out of the series configuration during phase angles where the target voltage is rapidly changing, or where optimised accuracy to the voltage target is not important. Such a decision is observable in Figure 7(B) where the first switch transition connects only a single battery module such that a smaller voltage step is achieved, with the resulting common mode current spike.

[0145] In some embodiments, the controller is configured to store data representing predetermined common mode current magnitudes at each node resulting from a variety of switch transitions. From the data, a combination current magnitude of can be determined to minimise an EMC profile for the system. For example, if arbitrary nodes A and B each have a current magnitude of +1 Amp, and node F has a current magnitude of -2 Amps, then a switch profile can be determined which combines nodes A, B and F to substantially minimise the combined common mode current and therefore elicit the predetermined common mode energy emission profile of the system.

[0146] Many other combinations of switch transitions are possible based on the node profile information such a low noise profile, or accuracy to voltage target, or other objectives can be prioritised as desired. In one exemplary embodiment the controller is configured to prioritise switch transitions based on one or more priority data including meeting a threshold accuracy for the voltage output to a target by control of one or more battery modules in or out of the series configuration, and meeting a threshold EMC noise output by control based on node profile information.

[0147] In some embodiments there is a controller configured to determine whether minimising spectral noise, or creating a spectral noise notch based on one or more compliance factors, and control the operation of the switching circuit based on that input. An exemplary compliance factor is based on a predetermined EMC profile such as a maximum emissions restriction the system may be required to meet particular certifications. In some embodiments, the controller is configured to operate the switching circuit based on a mixture of operating modes, one mode being operation of the switching circuit to control spectral notches, and another mode being operation of the switching circuit to minimise the overall emission. The aforementioned balanced circuit operation provides one option for lowering the overall emission, and as such, balanced circuit operation may be operated for some switching events in a sequence of switching events.

[0148] In some embodiments, the controller is configured to determine a switching event based on the difference, or an upcoming difference, between the current output voltage and a new target output voltage. Based on this difference, the controller will select one or more battery modules for including into or excluding from the series configuration of battery modules. The modules selected for inclusion or exclusion are controlled, and in some cases, the timing of the switching event(s) controlled, such that a desired emission is created. The magnitude of the emission is is determined by the relative position to the node zero, and the relative position to the node end, the unit current (lu) which is defined by the voltage step (dv / dt) and parasitic capacitance (C of each node).

[0149] For example, if there are twenty nodes in the battery system and the next required emission magnitude is (4 * lu), the following switches provide options for creating the desired emission: Switch off node 12: (12-0)-(20-12) = 4 Switch On node 8: -((8-0)-(20-8)) = 4

[0150] Switch off node 6 and node 16: ((6-0) - (20-6)) + ((16-0) - (20-16)) = -8 + 12 = 4

[0151] And so on. Based on there being two or more options available, the controller may prioritise battery module parameters such as state of health and state of charge to determine which option to select. For example, if the controller determines that either switching cell #3 alone, or switching the pair of cells #8 and #12 together, would achieve the required voltage step while satisfying the EMC profile, it may then consult the cell selection criteria. If cell #3 has a significantly higher state of charge than cells #8 and #12, the controller may select the option of switching cells #8 and #12 to promote balanced energy usage across the battery pack. Conversely, if EMC control is the highest priority, it may select the option that creates the deepest spectral notch, regardless of the cells state of charge. Figure 8 shows the common mode current spectrum 53 that uses a selection based on the above described node profile information compared to the spectrum 52 where battery modules are connected arbitrarily such as, for example, based on regular methods such as battery module parameter including one or more of a state of charge or state of health of a battery module. Observable is the creation of spectral maxima and minima with peaks around 10dB higher and notches of around -30dB. The strength of the maxima and minima, and location of the harmonics is based in part on the node profile information and the underlying balancing of common mode current from select combinations of battery modules which are included or bypassed from the series configuration.

[0152] Spectral information for arbitrary (random) node switching profile, and the spectral information from the profile-based switching control are respectively as follows:

[0153] [Equation 5]

[0154] Equation 4 represents a random noise (A_random_z) shown as line 52, where Equation 5 represents the profile (A2) based switch control shown as line 53.

[0155] Figure 9 shows a battery system having a number of battery cells modules of the kind described with reference to Figures 1 and 2 where each module contains two series connected battery cells. The circuit of the battery system is configured in a similar arrangement to that shown by Figure 5 whereby there are eleven nodes (nodes 0-10) positioned between the output terminals of the series configurable battery modules.

[0156] Figure 10 shows a graph of two examples two different node switching profiles defined by a cell selection algorithm which targets a time varying supply voltage overtime, each defined as follows:

[0157] [Equation 6]

[0158] A2(Z, A) = (-- - x z + 1) x (-l)z

[0159] [Equation 7] where A1 and A2 are the common mode current flow to earth caused by switch position Z, and Nswis node profile information which defines the total number of switch positions available in the system. In the first selection algorithm 50 (represented by Equation 6), the cell modules are connected into the series configuration in a sequence from one end of the arrangement to the other, or with reference to the circuit of Figure 8, from the left battery module to the right battery module. That is, transitioning the switch in position 0 sequentially to position 10. With reference to the switches, the top left switches are connected to the bottom right.

[0160] In the second selection algorithm 51 (represented by Equation 7), the cells modules are connected into the series configuration from opposite directions, starting from switches in positions closest to the opposing output terminals. For example, ten cells would have a stepped sequence of positions 0, 10, 1 , 9, 2, 8, 3, 7, 4, 6, then 5. With reference to the switches, those connected are from the top and bottom moving towards the centre of the arrangement.

[0161] Each of the data points shown represents the peak value of an exponential current waveform and the time constant of the waveform is defined by the parasitic components.

[0162] Figure 11 shows the resulting noise spectrum of the common mode current for each of the two exemplary cell selection algorithms based on the selected operation of the node profiles. The exemplary cell selection algorithms of equations 6 and 7 are identified as lines 53, 54. Harmonic peaks are evident at frequencies determined by the node profile and with harmonic peaks separated by the timing profile.

[0163] Figure 12 shows a graph of the current spectrum showing the magnitude of the spectral noise notches which are created. Notable is the first notch is controlled by the profile of nodes switched over time (node profile), while the location of subsequent notches are controlled by the timing profile of node switching events. The strategy implemented by the controller relies on the manipulation of two distinct but related control inputs. The first is the node profile, which is based on the physical or electrical position of the battery modules. The selection of which nodes to switch, as dictated by the node profile, primarily determines the frequency of the fundamental spectral notch. The second is the timing profile, which governs the time intervals between switching events. The timing profile primarily determines the spectral spacing and characteristics of subsequent harmonic notches. By independently or cooperatively controlling these two profiles, the controller can precisely shape the overall common mode spectral noise profile.

[0164] In the example shown, the node profile is controlled such that a 5 kHz notch 120 is created, while subsequent notches are controlled by the timing profile which includes the timing interval of a sequence of switching events. In this example, the first notch 121 is created at 5kHz (first vertical line 120) by the profile, and the timing interval creates orders of 5kHz (second vertical line 121), meaning that controlled notch is at 5kHz and subsequent orders 122, 123 etc of 10, 15, 20kHz and so on are produced by the timing interval.

[0165] In some embodiments, the strength of the spectral notches can be controlled by the precision of the timing of switching events. Precise timing of switching events create a narrow notch with a strong magnitude, whereas imprecise timing of switching events broadens the spectral width of created notches and reduces their magnitude. In some embodiments, the strength of the spectral notch is controlled based on the sensitivity of other parts of the battery system. This allows the operator of a battery system some flexibility in the timing of switching events or node profile operated such that noise can be reduced while not adversely affecting the accuracy of the output voltage to a target output voltage.

[0166] Node profiles for alternative circuit layouts

[0167] A switching algorithm, defining which battery cell modules are selected for inclusion or exclusion into the series configuration overtime, are chosen based on knowledge of what the magnitude of common mode current would be, and the magnitude of common mode current comes through the spatial distribution of capacitance or at least a distribution of capacitance as the nodes, per node. Should the distribution of capacitance over each node be nonlinear, a linearising or correcting function can be applied. The node profile may therefore include position information for battery cell modules where the parasitic capacitance accumulates linearly across the geometric arrangement of battery cell modules, or it may include a nonlinear accumulation of parasitic capacitance, where the profile further includes a linearising function. The position information can be stored as positional identifiers associated with the geometrical arrangement of each battery cell module in the predetermined geometric configuration. In one example, positional identifiers include physical position information of each the plurality of battery modules relative to the supply terminals of the circuit. The node profile may also include data indicating the proximity of each battery cell module to a reference point of the battery system, where the reference point is the neutral, line or earth point.

[0168] The node profile may therefore include node data including any one or more of a connection between two battery cell modules, a connection between a battery cell module and a switch and / or discrete locations of the switching circuit each comprising a different common mode parasitic capacitance to other discrete locations. Parasitic capacitance may be determined based on common mode parasitic capacitance of each node.

[0169] Figures 13 to 16 show exemplary alternative configurations of battery system layouts and node profile information of those circuits, where the nodes are indicated based on having and unique parasitic capacitance. Each exemplary layout shows two or more modules of the circuit which may be repeated any number of times to build a bigger system. The overall size of the system is typically such that a voltage and / or current target can be met with some overhead and may include hundreds of battery modules and nodes.

[0170] Figure 13 shows an exemplary reconfigurable battery system layout with switches configured forthe connection or bypass of individual cell modules with a series configuration of cells. The pattern of the modules is repeatable to create any number of nodes.

[0171] Figure 14 shows another exemplary reconfigurable battery system layout which allows limited connection and bypass of cell modules in the circuit. The pattern of cell module columns is repeatable to create any number of nodes.

[0172] Figure 15 shows another exemplary reconfigurable battery system layout with switches configured for the connection or bypass of individual cell modules with a series configuration of cells. The pattern of the modules is repeatable to create any number of nodes.

[0173] Figure 16 shows another exemplary reconfigurable battery system layout with switches configured for the connection or bypass of individual cell modules with a series configuration of cells. The pattern of the modules is repeatable to create any number of nodes.

[0174] In some embodiments, the controller is configured to receive position information of battery cell modules to define a node profile, and operate the switching circuit based on at least the node profile. Controller operation

[0175] Embodiments relate to a reconfigurable battery system that is operated to transfer power and where the common mode energy emissions are controlled according to a desired common mode emission profile. The control is based on the operation of the switching circuit which has switches configured to selectively connect or bypass a battery cell module in or out of a series configuration with one or more other cell modules and the supply terminals. Hence, control operations apply to the increase or decrease in voltage applied to the supply terminals. In some embodiments, a control objective is to eliminate or modulate the switching circuit to control the common mode noise. In some embodiments, the emission profile includes one or more frequency ranges where reduced noise is to be targeted. In one illustrative example, an analogue to digital converter operates at a 1 MHz sampling rate, and therefore the controller operates the switching circuit to target reduced noise in a frequency range including 1 MHz or an order thereof. The frequency range may be any suitable range which provides the desired outcome, and in some embodiments the range is controlled by the timing of switching intervals.

[0176] A controller is configured to operate the switching circuit to control the battery modules connected in the series configuration and elicit the predetermined common mode energy emission profile based on the node profile and the timing profile. The controller is also configured to selectively connect cells in series to meet an output voltage target. Depending on the target output voltage, there will be several options available to the controller regarding which cells could be connected to, or disconnected from, the series connection in order to change the output voltage from the current level to a desired new level to meet a change in the target voltage. In some embodiments, the controller is configured to select one or more battery modules for connection or disconnection based on factors including state of charge (SOC), state of health (SOH). These SOC and SOH factors are derived from a variety of parameters including, for example, cell voltage, capacity, and operating temperature of each battery module. In some embodiments, the controller is configured to rank these parameters and select a cell for inclusion or exclusion from the series configuration of battery modules based on the rank. In some embodiments, the controller is configured to remove from availability any one or more battery modules which do not meet emissions requirements. The availability of each battery module may be determined at each time a switch state of the switching circuit is intended to change (such as to meet a voltage target) or it may be determined after a predetermined time period, or when a system event occurs.

[0177] In some embodiments, the controller is configured to determine the eligibility of each battery module for inclusion or exclusion in the series configuration from the cell parameters. For example, the controller may have a requirement to connect one additional battery module to meet a target output voltage, and have five battery modules which are eligible for connection based on their meeting of one or more eligibility criteria. The controller may be configured to select one of those battery modules based on a rank determination. In some embodiments, the controller is configured to select one of those battery modules based on common node noise considerations. Those considerations include whether the connection of one or more of the eligible battery modules will support the control of spectral noise characteristics, in particular, whether a spectral notch will be created, or remain, at a target frequency.

[0178] In some embodiments, the node profile is based on the position information of battery cell modules. Position information relates to the position of each cell module with respect to the common mode reference point of the system, such as as a line or neutral references, or a midpoint of line or neutral. In some embodiments, the position information is information relating the location of each node in a geometrical arrangement of the battery system. For example, the location of each node with respect to a supply terminal.

[0179] The geometric arrangement may be characterised by physical battery module positions. It is most advantageous to align each battery module such that its terminals are in close proximity to each other in order to ensure minimal conduction path lengths. For this reason, battery modules are typically arranged in rows. Exemplary geometric arrangements therefore include a stacked row of battery modules, and there may be several rows and one or more columns. Further, the rows and / or columns may extend in any direction, including vertically or horizontally.

[0180] In some embodiments, the controller is configured to store data pertaining to switch positions in the switching circuit and their schematic relationship to a common current path including Line or Neutral. Due to the coupling capacitance between nodes and the ground plane, such as the chassis, common mode current occurs and flows into the ground plane. In some embodiments, the controller is configured to store a switching circuit control algorithm which assigns different weights to different positions or position combinations defining common mode currents. In such embodiments, the switching circuit is operated based on that control algorithm.

[0181] In some embodiments, the controller is configured to empirically determine node profile information based on closed loop control. For example, the system may include a current sensor configured to measure common mode currents, and the node profile is based on common mode current measurements determined when each node changes potential. Exemplary current sensing devices include shunt resistors and hall based field sensors located in a current return path.

[0182] In some embodiments, the controller is also configured to operate the switching circuit of the system based on the timing profile. The timing profile defines a time interval for a switching event of one or more switches of the switching circuit. As discussed above, the timing profile is determinative of the relative location and magnitude of spectral notches. In some embodiments, the controller is configured to operate the switching circuit based on the timing profile, where the timing profile includes a time based tolerance of when a switching event may occur. Switch timing may be more critical at some times over others, based on considerations such as the accuracy of the output voltage to the target output voltage, and the sensitivity of any load to the shape of any resulting time varying output voltage.

[0183] In some embodiments, the time interval tolerance is determined to control the magnitude of the spectral notch. Highly accurate or consecutively similar time intervals creates a narrow notch with a large magnitude, whereas inaccurate or consecutively dissimilar time intervals creates a wider notch with less magnitude. In some embodiments, the controller is configured to control the repeatability of time intervals to thereby control the spectral width and magnitude of a notch. The controller is configured to operate the switching interval within a time interval, and deliberately controls the switching intervals to be the same, or different, and / or how different, based on the desired notch characteristics. For example, the controller may implement a method of spreading the switching circuit control operation throughout a time interval tolerance window. In one method, the controller randomises the precise timing of a switching operation within the time interval tolerance period. In another method, the controller implements a pattern which distributes the switching operations within the time interval tolerance window. Further, adjustment of the timing interval or adjustment of the time interval tolerance period may be desired to allow an output voltage at the supply terminals to more closely follow a target supply voltage.

[0184] Therefore, the controller of the battery system may control the battery modules based on any one or more of battery module cell parameters, the common mode noise performance based on the node profile, and a timing tolerance based on the timing profile.

[0185] In some embodiments, the controller is configured to rank the selection of eligible battery modules for inclusion or exclusion in the series configuration, for any particular operation of the switching circuit, based on the following considerations:

[0186] • a node profile which is balanced to thereby minimising emissions;

[0187] • a node profile which minimises emissions at a target frequency;

[0188] • one or more cell parameters based on SOC and SOH.

[0189] The rank of the modules is used to prioritise the modules for inclusion or exclusion for a particular operation of the switching circuit.

[0190] In one exemplary embodiment, the controller is configured to determine the availability of a node profile which includes two or more battery modules which offer a balanced emission, or are balanced within a threshold defined by the summed capacitive coupling. With reference to the circuit of Figure 9, examples include node position 0 which may be balanced with position 9, and another example includes node positions 0, 7 and 8 which are balanced within a threshold. This means that the controller is able to operate the switching circuit to include these node position combinations in a control operation of the switching circuit to control spectral emissions.

[0191] In another example, the controller is configured to de-rank selectable nodes options based on the generation of unwanted emission frequencies. In one exemplary embodiment, the controller determines there are five eligible battery modules for inclusion into the series configuration, the controller further determines from the profile information that one or more of those five would create unwanted spectral emissions, then, the controller is configured to de-rank or remove those one or more battery modules from eligibility.

[0192] In some embodiments, the controller is configured to control the timing profile by adjusting the timing interval between node switching events based on each node affected by a switching event. The timing interval can be adjusted to ensure that spectral harmonics align with a target frequency and a desired spectral width and magnitude of a notch is controlled. The target frequency may change overtime. Further, the target frequency may be represented by data input to the controller from an external source. The target frequency may also be determined by the controller based on data including ADC sampling frequencies, the clock speed of any processing devices, or other data representing the proximate circuit of the battery system.

[0193] In one embodiment, the controller is configured to execute a sequence of steps to control operation of the switching circuit and control the desired frequency response of generated emissions based on any of the following control steps, including, in any order:

[0194] A first step where the controller is configured to define the node profile by the assignment of positional numbers to the switches of the switching circuit based on the geometric position of each node relative to the supply terminals. Next, the controller determines the common mode currents that would flow out into the ground plane (chassis) as a result of each node changing voltage potential (such as represented by Equation 1). A second step where the controller calculates the common mode current profile, based on the common mode current of each node at each switch event, that would flow out into the ground plane as a result of activating combinations of the positions (such as represented by Equation 2).

[0195] A third step where the controller determines the location of one or more spectral notches based on the timing profile and a target frequency. Optionally, the controller is configured to determine multiple frequency profiles, and optionally, the controller is configured to determine a timing profile based on a target spectral noise profile. For example, the operation interval of the switching circuit is used to determine one or more common mode current frequency spectral profiles based on a conversion between the time and frequency domains. For example, the controller performs a FFT for the next time interval, such as 20 us for example for a 50 Hz AC output, to identify undesirable frequency peaks in the current spectral profile, then selects an alternative switching algorithm in order to avoid or minimise or reduce the undesirable frequency peaks.

[0196] A fourth step where the controller identifies that a spectral profile is desired based on the determination from step 3.

[0197] A fifth step where the controller assigns a rank to nodes based on the desired spectral profile, or, determines that a current spectral profile is undesirable, and assigns corresponding weights to unpreferred positions / combinations of switches based on the current spectral profile.

[0198] A sixth step where the controller determines or receives a target frequency representing a desired spectral notch and thereby a predetermined common mode energy emission profile. The controller then determines a switching operation based on the node profile information and the timing profile information. Once the switching operation is determined, the controller controls the switching circuit to meet the target output voltage and control the emission profile.

[0199] Therefore, embodiments have been described in which the controller is able to operate the switching circuit to elicit a predetermined common mode energy emission profile. The controller is able to use the node profile based on position information of battery cell modules, and the timing profile defining a time interval for a switching event of one or more switches of the switching circuit such that desired spectral emissions are created. The controller is further able to operate the switching circuit based on the node and timing profiles in addition to the SOC and SOH information based on system priorities. Further, those skilled in the art will appreciate the following based on the teaching of the present disclosure: Dynamically adjust the switch timing to control noise emissions, with the objective of targeting a low noise spectrum at a specific frequency; Generating a specific noise profile by adjusting the switching sequences and timing, wherein the noise profile is determined by desired spectral EMC characteristics; Providing a noise profile generator that calculates the optimal switch timing and sequence based on the capacitive coupling data from each node and the desired EMC emissions; Control the timing of the switches to connect or disconnect the battery cell modules in series determined by a predetermined algorithm based on EMC spectral profiles; Generating a specific EMC noise profile by dynamically adjusting the switching sequences and timing, where the noise profile is determined by desired EMC spectral emissions characteristics; Targeting a low noise EMC spectrum at a specific frequency by minimising noise components at the target frequency through precise control of the switch timing and sequence; and using feedback from sensors monitoring the capacitive coupling at each node to continuously refine the noise profile and maintain optimal spectral emissions.

[0200] Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

[0201] Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and / or improvements may be made without departing from the scope or spirit of the invention.

Claims

Claims1 . A system for controlling common mode energy emissions in a reconfigurable battery system, the system comprising: a plurality of battery cell modules arranged in a predetermined geometric arrangement; a switching circuit comprising a plurality of switches, each configured to selectively connect or bypass one of the battery cell modules from a series connection; and a controller operatively coupled to the switching circuit, the controller configured to: determine a node profile based on position information associated with the geometric arrangement of the battery cell modules; determine a timing profile defining a time interval for switching events; and operate the switching circuit to selectively connect or bypass one or more of the battery cell modules based on the node profile and the timing profile to control a common mode energy emission profile of the system.

2. The system of claim 1 , wherein the controller is further configured to operate the switching circuit to meet a time-varying target output voltage.

3. The system of claim 1 or 2, wherein the predetermined geometric arrangement comprises at least one row of battery cell modules, and wherein the position information comprises data indicating the proximity of each battery cell module relative to one or more supply terminals.

4. The system of any one of claims 1 to 3, wherein the position information is indicative of a common mode parasitic capacitance of each of a plurality of nodes within the switching circuit, each node being associated with a respective battery cell module.

5. The system of claim 4, wherein the nodes are defined by at least one of: a connection between two battery cell modules, or a connection between a battery cell module and a switch.

6. The system of any one of claims 1 to 5, wherein the common mode energy emission profile comprises a common mode spectral noise profile having one or more spectral characteristics.

7. The system of claim 6, wherein the controller is configured to operate the switching circuit based on the node profile to define a frequency of at least one spectral notch in the common mode spectral noise profile.

8. The system of claim 7, wherein the controller is configured to operate the switching circuit based on the timing profile to define a spectral spacing of one or more harmonics in the common mode spectral noise profile.

9. The system of claim 7 or 8, wherein the timing profile comprises a time tolerance period, and wherein the controller is configured to vary a timing of the switching events within the time tolerance period to adjust a width of the spectral notch.

10. The system of claim 9, wherein the controller is configured to dynamically alter a magnitude of the spectral notch by adjusting the timing profile to control an overlap of the switching events.11 . The system of any one of the preceding claims, wherein the controller is configured to operate the switching circuit by selecting a combination of switches having a balanced spectral noise profile based on the node profile.

12. The system of claim 11 , wherein the controller is configured to select the combination of switches corresponding to battery cell modules at substantially opposite electrical positions within the geometric arrangement to achieve the balanced spectral noise profile.

13. The system of any one of the preceding claims, wherein the controller is further configured to select the one or more battery cell modules based on cell selection criteria comprising at least one of: a state of charge (SOC), a state of health (SOH), or a battery module rank.

14. The system of claim 13, wherein the controller is configured to prioritize the control of the common mode energy emission profile over the cell selection criteria when selecting the one or more battery cell modules.

15. The system of claim 14, wherein the controller is configured to determine whether to prioritize the control of the common mode energy emission profile or the cell selection criteria based on one or more compliance factors.

16. The system of claim 2, wherein the controller is further configured to: identify, based on the node profile, one or more battery cell modules for inclusion in or exclusion from the series connection to provide the target output voltage; and operate the switching circuit based on the timing profile to include or exclude the identified battery cell modules and control the common mode energy emission profile.

17. The system of any one of the preceding claims, wherein the controller is configured to execute a sequence of switching events according to the timing profile and the node profile to generate a predetermined common mode energy emission pattern.

18. The system of any one of the preceding claims, further comprising one or more sensors configured to monitor the common mode energy emissions.

19. The system of claim 18, wherein the controller is configured to update the node profile and the timing profile in real time based on feedback from the one or more sensors.

20. The system of claim 18 or 19, wherein the one or more sensors comprises a current sensor configured to sense a parasitic current caused by operation of the switching circuit.

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