Systems, methods, controllers, and media for controlling discharge of a battery pack

Abstract

A method, system, controller and medium for controlling discharging of a plurality of battery banks are provided. The method includes receiving a total power demand required; collecting characteristic data of each battery bank of the plurality of battery banks to establish a first voltage-charge curve of each battery bank; determining a voltage gradient of each battery bank based on the first voltage-charge curve; controlling the voltage gradient of each battery bank to be below a predetermined threshold by changing a charge and a corresponding voltage of the respective battery bank and establishing a second voltage-charge curve; calculating a respective discharge share of each battery bank based on the charge and voltage in the second voltage-charge curve of each battery bank and the total power demand; and controlling discharging of the plurality of battery banks and / or controlling a particular battery bank to remain idle based on the respective discharge share. The present invention enables a plurality of battery banks to collectively supply power to meet a power demand while each battery bank can be discharged at a different share or rate.

Description

[0001] Priority claims and cross-references

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 17 / 241,528, filed on April 27, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to systems and methods for controlling battery packs. More specifically, the disclosed subject matter relates to controllers, systems, methods, and media for controlling the discharge of battery packs, for example, in stationary energy storage applications. Background Technology

[0004] With increasing concern about environmental issues such as global warming, clean and renewable energy has become more important. These energy sources include solar and wind power, as well as battery storage. Renewable energy is inflexible because it cannot be dispatched to meet the changing demands of energy consumers. Energy storage systems are expected to address this flexibility challenge. Stationary energy storage systems can store energy and release it as electricity when needed. Summary of the Invention

[0005] This disclosure provides a method for controlling the discharge of a battery pack, comprising: receiving a total required power demand; collecting characteristic data of each battery pack in a plurality of battery packs to establish a first voltage-charge curve for each battery pack; determining a voltage gradient for each battery pack based on the first voltage-charge curve; controlling the voltage gradient of each battery pack to be below a predetermined threshold by changing the charge and corresponding voltage of the respective battery packs, and establishing a second voltage-charge curve; calculating a corresponding discharge share for each battery pack based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand; and controlling the discharge of the plurality of battery packs and / or controlling a specific battery pack to remain idle based on the corresponding discharge share of each battery pack.

[0006] Preferably, controlling the voltage gradient of each battery pack to be below a predetermined threshold includes the following steps: identifying the maximum voltage gradient and the corresponding first battery pack among the plurality of battery packs; minimizing the maximum voltage gradient of the corresponding first battery pack to be below the predetermined threshold by changing the charge and corresponding voltage of the corresponding first battery pack; and repeating the identification and minimization steps in the remaining battery packs among the plurality of battery packs to establish a second voltage-charge curve for each battery pack.

[0007] Preferably, controlling a particular battery pack to remain idle includes: controlling the particular battery pack to remain idle when the corresponding discharge share of the particular battery pack approaches zero.

[0008] Preferably, the plurality of battery packs are heterogeneous battery packs, and the heterogeneous battery packs are formed by new batteries, secondary power batteries, or a combination of both.

[0009] Preferably, the plurality of battery packs are configured to be connected in parallel, in series, or in a combination of both.

[0010] Preferably, controlling the discharge of the plurality of battery packs includes: dynamically controlling the discharge of the plurality of battery packs by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

[0011] This disclosure also provides a controller for controlling the discharge of a battery pack, including one or more processors and at least one machine-readable storage medium encoded with one or more programs, wherein the processor is configured to execute the one or more programs to implement any of the methods described above for controlling the discharge of the battery pack.

[0012] Preferably, the controller is configured to control the plurality of battery packs to release power to the grid or a load.

[0013] This disclosure also provides a system for controlling the discharge of a battery pack, the system comprising: a plurality of battery packs; one or more power converters, each power converter coupled to at least one of the plurality of battery packs and configured to perform AC / DC conversion on the output current of the battery packs; and any of the above-mentioned controllers coupled to the plurality of battery packs and the one or more power converters to control the discharge of the plurality of battery packs and / or control a particular battery pack to remain idle.

[0014] Preferably, the system further includes one or more battery power management units (BPMUs), each BPMU being connected to one or more battery packs and configured to monitor the one or more battery packs and provide characteristic data of the one or more battery packs to the controller.

[0015] Preferably, the system is an electric energy storage system, and the total power demand is configured to be received from an upper-level energy management system.

[0016] This disclosure also provides a machine-readable storage medium storing instructions that cause a machine to perform any of the methods described above for controlling the discharge of a battery pack.

[0017] This disclosure provides a controller for controlling the discharge of a heterogeneous battery pack, a battery energy storage system including such a controller, and a method for using the controller. According to some embodiments, the controller, system, and method utilize voltage gradient biasing technology.

[0018] According to some embodiments, a system includes multiple battery packs, one or more power converters, and a controller. Each power converter is coupled to at least one of the multiple battery packs and is configured to convert direct current (DC) to alternating current (AC) from one battery pack or convert AC from one battery pack to DC. The controller is coupled to the multiple battery packs and the one or more power converters. In some embodiments, the system may also include more than one controller, and each controller is coupled to multiple battery packs.

[0019] The multiple battery packs are heterogeneous battery packs, which may be selected from new batteries, reusable electric vehicle (EV) batteries, or combinations thereof. The multiple battery packs are connected in parallel, in series, or in a combination thereof. In some embodiments, the multiple battery packs are connected in parallel.

[0020] The controller includes one or more processors and at least one tangible, non-transitory, machine-readable medium encoded with one or more programs configured to perform steps for controlling the discharge process of a system having multiple battery packs. In some embodiments, these steps include: receiving a total power demand to be dispatched from the system; collecting characteristic data for each battery pack to establish a first voltage-charge curve for each battery pack; determining a voltage gradient for each battery pack based on the first voltage-charge curve; and changing the charge and voltage of the respective battery packs to control and / or reduce the corresponding voltage gradient of each battery pack to below a predetermined threshold. The changed charge and voltage form a second voltage-charge curve for each respective battery pack.

[0021] The steps further include: calculating the corresponding discharge share of each battery pack based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand to be scheduled; and providing signals with instructions to the plurality of battery packs and the one or more power converters for releasing power from the plurality of battery packs and / or keeping a particular battery pack idle based on the corresponding discharge share or rate of each battery pack.

[0022] When the calculated discharge share or rate of a particular battery pack is approximately zero, or when the battery cannot be used to discharge to meet the required conditions, the particular battery pack remains idle and does not discharge. This battery pack may need to be charged or replaced first.

[0023] In some embodiments, the step of reducing and / or controlling the corresponding voltage gradient of each battery pack includes the following steps: identifying the maximum voltage gradient among the multiple battery packs and the corresponding first battery pack, and reducing or minimizing the maximum voltage gradient of the corresponding first battery pack to below a predetermined threshold by changing its charge and corresponding voltage. It is assumed that the multiple battery packs are used for discharge and power dispatch. The step of identifying and minimizing the maximum voltage gradient is then repeated among the remaining battery packs in the multiple battery packs to establish a second voltage-charge curve for each battery pack. Therefore, a voltage gradient distribution curve is established for each battery pack in the multiple battery packs.

[0024] In some embodiments, the controller is also configured to dynamically control the discharge of multiple battery packs by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

[0025] The system may optionally further include one or more battery power management units (BPMUs). Each BPMU may be connected to one or more battery packs and configured to monitor the one or more battery packs and provide characteristic data of the one or more battery packs to the controller.

[0026] In some embodiments, the system is an electrical energy storage system. Total power demand is supplied from a higher-level energy management system (EMS). In some embodiments, the controller is configured to discharge power from multiple battery packs to the grid or loads. In some embodiments, the grid is optional. Power can be discharged to other components that require electrical power.

[0027] In another aspect, this disclosure provides a controller for controlling the discharge of a system comprising multiple battery packs. As described herein, such a controller includes one or more processors and at least one tangible, non-transitory, machine-readable medium encoded with one or more programs configured to perform the steps described herein. The controller is configured to perform the following steps: receiving a total power demand to be scheduled from the system; collecting characteristic data for each battery pack to establish a first voltage-charge curve for each battery pack; determining a voltage gradient for each battery pack based on the first voltage-charge curve; and changing the charge and voltage of the respective battery packs to control and / or reduce the corresponding voltage gradient of each battery pack to below a predetermined threshold in a second voltage-charge curve. The controller is also configured to calculate a corresponding discharge share or rate for each battery pack based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand to be scheduled; and to provide signals with instructions to the multiple battery packs and / or one or more power converters for releasing power from the multiple battery packs based on the corresponding discharge share of each battery pack and / or keeping a particular battery pack idle as described herein.

[0028] The steps of reducing and / or controlling the voltage gradient of each battery pack include: identifying the maximum voltage gradient among multiple battery packs and the corresponding first battery pack, and minimizing the maximum voltage gradient of the corresponding first battery pack to below a predetermined threshold by changing its charge and corresponding voltage. The steps of identifying and minimizing the maximum voltage gradient are repeated among the remaining battery packs in the multiple battery packs to establish a second voltage-charge curve for each battery pack.

[0029] Multiple battery packs (to which the controller is configured to couple) are heterogeneous battery packs selected from new batteries, recycled power batteries (including recycled electric vehicle (EV) batteries), or combinations thereof. The multiple battery packs are connected in parallel, series, or in combination thereof. The controller is also configured to dynamically control the discharge of the multiple battery packs by instantaneously updating the corresponding discharge share of each battery pack over time.

[0030] The controller is configured to control the discharge of heterogeneous battery packs, such as in an energy storage system. In some embodiments, the controller is configured to optionally discharge power from multiple battery packs to the grid or a load.

[0031] On the other hand, this disclosure provides a method for controlling the discharge of a system comprising multiple battery packs via a controller as described herein. The method includes the steps of: receiving a total power demand to be dispatched from the system; collecting characteristic data of each battery pack to establish a first voltage-charge curve for each battery pack; determining a voltage gradient for each battery pack based on the first voltage-charge curve; and controlling the voltage gradient of each battery pack to be below a predetermined threshold by changing the charge and corresponding voltage of the respective battery pack to provide a second voltage-charge curve.

[0032] The method further includes the following steps: calculating the corresponding discharge share of each battery pack based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand to be scheduled, and releasing power from multiple battery packs based on the corresponding discharge share of each battery pack.

[0033] The steps of controlling and / or reducing the corresponding voltage gradient of each battery pack include: identifying the maximum voltage gradient among multiple battery packs and the corresponding first battery pack, and minimizing the maximum voltage gradient of the corresponding first battery pack to below a predetermined threshold by changing its charge and corresponding voltage. It is assumed that the multiple battery packs are used for discharge and power dispatch. The steps of identifying and minimizing the maximum voltage gradient are then repeated among the remaining battery packs in the multiple battery packs to establish a second voltage-charge curve for each battery pack.

[0034] In some embodiments, a particular battery pack may remain idle if the corresponding discharge share of a particular battery pack is approximately zero, or if it cannot be used under certain conditions.

[0035] Multiple battery packs are heterogeneous battery packs, selected from new batteries, recycled power batteries, or combinations thereof. Multiple battery packs are connected in parallel, in series, or in combination thereof.

[0036] In some embodiments, instructions are sent from the controller to each battery pack and / or one or more converters connected to multiple battery packs for discharging based on a corresponding discharge share of each battery pack.

[0037] In some embodiments, the discharge process of multiple battery packs is dynamically controlled by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

[0038] The systems, controllers, and methods provided in this disclosure offer numerous advantages. For example, a variety of new and used battery packs of varying qualities can be used. Pre-selection or removal of battery packs is not required. Multiple heterogeneous battery packs can collectively supply the electrical load to meet power demands, while each battery pack can discharge at a different share or rate. The systems, controllers, and methods extend the lifespan of each battery pack, and they also provide flexibility in maintaining and upgrading the system. Attached Figure Description

[0039] This disclosure can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features in the drawings are not necessarily drawn to scale. Rather, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced. Throughout the specification and drawings, the same reference numerals denote the same features.

[0040] Figure 1 This is a block diagram illustrating an exemplary system including a heterogeneous battery pack and a controller according to some embodiments.

[0041] Figure 2 This is a block diagram illustrating an exemplary controller for controlling the discharge of multiple heterogeneous battery packs according to some embodiments. The exemplary controller includes one or more processors and at least one tangible, non-transitory machine-readable medium encoded with one or more programs.

[0042] Figure 3 The relationship between voltage (V) and charge flow (Ah) of exemplary battery packs in some embodiments is shown.

[0043] Figure 4 A battery pack (Ω) according to some embodiments is shown. i The scheduling share is iteratively calculated to minimize the voltage gradient while satisfying scheduling constraints.

[0044] Figures 5A-5B This is a flowchart illustrating an exemplary method for controlling the discharge of a battery pack according to some embodiments.

[0045] Figure 6 This is a flowchart illustrating an exemplary procedure for controlling the discharge of a battery pack according to some embodiments.

[0046] Figure 7 Two exemplary battery packs with different voltages are shown, which are scheduled using the procedures and algorithms provided in this disclosure.

[0047] Figure 8 This demonstrates a comparison of power dispatching with the same battery pack using existing technology. Figure 7 The power scheduling of the two exemplary battery packs varies over time. Detailed Implementation

[0048] The description of exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are considered an integral part of the entire written description. In this specification, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “upward,” “downward,” “top,” and “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to orientations as described subsequently or as shown in the drawings discussed. These relative terms are for ease of description and do not require the device to be constructed or operated in a particular orientation. Terms relating to attachment, coupling, etc., such as “connection” and “interconnection,” refer to a relationship in which structures are directly or indirectly fixed or attached to each other through intermediate structures, and movable or rigid attachments or relationships, unless otherwise explicitly described.

[0049] For the purposes described below, it should be understood that alternative variations and embodiments may be assumed. It should also be understood that the specific articles, combinations, and / or processes described herein are exemplary and should not be considered limiting.

[0050] In this disclosure, the singular forms “a,” “an,” and “the” include plural references, and references to a particular numerical value include at least that particular numerical value unless the context clearly indicates otherwise. When a value is expressed as an approximation using the antecedent “about,” it should be understood that the particular value forms another embodiment. As used herein, “about X” (where X is a numerical value) preferably refers to ±10% of the referenced value, including the end value. For example, the phrase “about 8” preferably refers to a value from 7.2 to 8.8, including the end value. Where applicable, all ranges are inclusive and composable. For example, when the range “1 to 5” is referenced, the referenced range should be interpreted as including the ranges “1 to 4,” “1 to 3,” “1-2,” “1-2 and 4-5,” “1-3 and 5,” “2-5,” etc. Furthermore, when a list of alternatives is provided affirmatively, such a list can be interpreted as meaning that any alternative can be excluded, for example, by negative limitation in the claims. For example, when referring to the range “1 to 5”, the referenced range can be interpreted to include cases where any one of 1, 2, 3, 4, or 5 is negatively excluded; thus, a statement of “1 to 5” can be interpreted as “1 and 3-5, but not 2”, or simply “excluding 2”. The intent is that any component, element, property, or step explicitly referenced herein may be explicitly excluded from the claims, whether such component, element, property, or step is listed as an alternative or whether it is referenced individually.

[0051] U.S. Patent Application Publication No. 2010 / 0285339A1 discloses a method for charging and discharging an electrochemical battery system, such as a lithium-ion battery system with two cells. Battery discharge is determined based on a state of charge (SOC) threshold defined in the system. The criterion for discharging the second cell in this system is based on a criterion associated with the first cell, rather than its own state. Australian Patent Application No. AU2018236771B2 describes a multi-source distributed energy storage system. However, in this system, two power sources cannot operate simultaneously.

[0052] Chinese patent application CN110518667A discloses a parallel battery system for cascaded utilization, including a battery module and a DC / DC power conversion module. In this battery module, multiple battery packs are connected in parallel, and each battery pack consists of several battery packs connected in series. The battery packs are connected in series to provide similar voltages in the corresponding parallel-connected battery packs. The system utilizes the DC / DC conversion module and a battery management module within the battery module to control the battery system.

[0053] The system disclosed in CN110518667A ignores the type of new or used battery and the circulating current between series-connected battery packs. The disclosed technology limits the scalability of this system to the power grid. A DC-DC converter module is an electronic circuit or electromechanical device that converts a direct current (DC) source from one voltage level to another. If the battery system is connected to the power grid, an additional AC / DC converter is still required. If a system such as that disclosed in CN110518667A is connected to the power grid, adding more DC / DC converter modules will significantly increase the total DC current and increase the hardware requirements for the AC / DC converter.

[0054] This invention provides a method and controller for controlling the discharge of, for example, heterogeneous battery packs, and a system (e.g., an energy storage system) including such a controller. According to some embodiments, the controller, system, and method utilize voltage gradient biasing techniques. Multiple battery packs can be discharged simultaneously. The priority of the discharge and scheduling share or rate of the multiple battery packs is determined by the voltage biasing described herein.

[0055] One objective of this invention is to establish a method for discharging multiple battery packs based on data collected from the battery pack (or interpolated historical currents) and the battery pack voltage. This data is used to establish a voltage-charge curve, upon which the voltage gradient of each battery pack is calculated. The voltage gradient provides a measurement of the state of charge of such a battery pack and its ability to provide energy. Battery packs exhibiting lower voltage gradients are prioritized to provide more power than those with higher voltage gradients.

[0056] Power dispatch (discharge) is a function of charge flow and voltage. For the same amount of charge flow, a lower voltage gradient provides a more stable energy supply compared to a higher voltage gradient. Early methods did not consider the impact of voltage gradient on energy dispatch decisions. Furthermore, they did not take into account the non-uniformity of voltage gradients within the battery pack.

[0057] This invention provides a controller, system, and method for appropriately utilizing, for example, heterogeneous battery packs in stationary energy storage applications. These heterogeneous battery packs include new batteries from different manufacturers, secondary power batteries (such as secondary electric vehicle (EV) batteries), or a combination of both. Each battery pack operates independently based on its characteristics (e.g., voltage gradient). Pre-selection or disassembly of battery packs is not required.

[0058] One benefit of this invention is the efficient management of battery pack diversity, such as new batteries, recycled EV batteries, or combinations thereof in stationary energy storage applications. The utilization rate of stronger (healthier) battery packs in multi-pack systems can be improved. The lifespan of EV battery packs can be uniformized, and the overall system lifespan can be extended. This improves the reliability, stability, and safety of battery energy storage systems (BESS).

[0059] The controllers, systems, and methods provided in the embodiments of this invention are applicable to different battery packs, such as heterogeneous battery packs. As used herein, "heterogeneous battery pack" refers to a battery pack or module with different capacities, states of charge (SOC), states of health (SOH), and / or voltage gradients, and can be selected from new batteries (e.g., from different manufacturers), cascaded power batteries (cascaded EV batteries), or combinations thereof. Cascaded EV batteries are used for illustrative purposes. References to "discharging" or "charging" multiple battery packs are understood to mean that multiple battery packs are simultaneously discharging or being charged, while some battery packs may remain idle (neither charging nor discharging).

[0060] Unless otherwise explicitly stated, “State of Health (SOH)” as used herein shall be understood as a quality factor comparing the condition of a battery, battery cell, or battery pack to its ideal condition. SOH is expressed as a percentage (%). Ideally, the condition matching specifications is 100%. SOH can decrease over time and with use.

[0061] Unless otherwise explicitly stated, the “state of charge” (SOC) as used herein is defined as the charge level of a battery relative to its capacity. SOC is measured in percentage points, with 0% representing empty and 100% representing fully charged.

[0062] As used herein, the term "Human Machine Interface (HMI)" is understood to refer to a user interface (UI), which is the space where interaction occurs between a human and a machine. An HMI can involve an interface between a human and a machine that has physical input hardware, such as a keyboard, mouse, or any other human-machine interaction based on touch, vision, or hearing. Such a user interface may include other layers, such as output hardware, like a computer monitor, speakers, and printer.

[0063] As used in this article, “Energy Management System (EMS)” refers to a computer-aided tool system used by operators of a public power grid to monitor, control, and optimize the performance of a power generation or transmission system.

[0064] In embodiments of the invention, the terms "power demand" and "power requirement" are used interchangeably, as are the terms "converter" and "inverter." Each battery pack includes an inverter and a battery management unit (BMU) therein. For ease of description, the terms "power inverter" or "AC / DC power converter" are used to describe internal components within the battery pack, and the terms "power converter" or "power conversion system (PCS)" are used to describe a converter connected to one or more battery packs. The terms "battery management unit (BMU)" or "battery management system (BMS)" are used to describe internal components within the battery pack, and the term "battery power management unit (BPMU)" is used to describe a battery management unit connected to one or more battery packs.

[0065] In embodiments of the invention, the terms "electricity," "power," and "energy" are used interchangeably, and energy is described in units of time. Energy and electricity can change over time.

[0066] Unless otherwise expressly stated, the terms “connection” or “coupling” as used herein are understood to encompass different connections or couplings between or within components for conducting electrical power or transmitting signals for communication. Such connections or couplings can be in wired, wireless, or cloud-based modes.

[0067] exist Figure 1-2 In this document, identical items are denoted by the same reference numerals, and for the sake of brevity, the descriptions of the structures provided above with reference to the preceding figures will not be repeated. (See references) Figure 1-2 The exemplary structures and Figure 4 , 7 The data plots or sketches described in Figure 8 are used to illustrate the methods described in Figure 5-6.

[0068] refer to Figure 1 The exemplary system 100 includes one or more power converters 10, multiple battery packs 20, and a controller 60. Figure 1 The number and configuration of each component are for illustrative purposes only. The system can have any suitable number of each component in any suitable combination or configuration.

[0069] Each power converter 10 is coupled to at least one of a plurality of battery packs 20 and is configured to convert direct current (DC) from the battery packs to alternating current (AC) or convert AC from one battery pack to DC. The power converter 10 may also be referred to as a power conversion system (PCS) or an inverter.

[0070] The controller 60 is coupled to a plurality of battery packs 20 and one or more power converters 10. In some embodiments, the system may also include more than one controller 60, and each controller 60 is coupled to a plurality of battery packs 20.

[0071] The controller 60 may be directly or indirectly coupled to multiple battery packs 20. For example, in some embodiments, the exemplary system 100 may optionally further include one or more battery power management units (BPMUs), which may also be referred to as battery management units (BMUs). Each BPMU 30 may be connected to one or more battery packs 20 and configured to monitor one or more battery packs 20 and provide characteristic data of one or more battery packs 20 to the controller 60. In some embodiments, the controller 60 is configured to read data from each battery pack 20. This can be accomplished by each corresponding BPMU 30 connected to each battery pack.

[0072] The multiple battery packs 20 are heterogeneous battery packs, which may be selected from new batteries, recycled EV batteries, or combinations thereof. The multiple battery packs 20 are connected in parallel, in series, or in a combination thereof. In some embodiments, the multiple battery packs 20 are connected in parallel. There is no series connection between the battery packs, eliminating cycling current and losses.

[0073] like Figure 1 As shown, multiple battery packs 20 are connected in parallel. In some embodiments, the multiple battery packs 20 are reused (i.e., used) electric vehicle (EV) batteries. The EV batteries used can be directly used in the system without prior selection or removal. Each battery pack 20 includes one or more batteries. Each battery pack 20 may include an internal battery management unit (BMU) and an internal inverter. The EV battery packs 20 are removed from the vehicle and are not disassembled into modules. These EV battery packs 20 can be subjected to simple tests to verify their State of Health (SOH).

[0074] In some embodiments, exemplary system 100 is an electrical energy storage system. Controller 60 is configured to receive total power demand from an upper-level energy management system (EMS) 110. In some embodiments, controller 60 is configured to discharge power from multiple battery packs 20 in DC form to a power grid or load 85 in AC form. Exemplary system 100 can be used to discharge power from battery packs 20 to the power grid 85, or to charge battery packs 20 from the power grid 85. Wiring connections 12 may be used. Figure 1 The dashed line 13 in the diagram shows an alternative power cable. Multiple power cable topologies can exist between the converter 10 and the battery pack 20. System 100 directly uses the grid-connected AC / DC converter 10, which offers flexibility in size expansion. Grid-connected applications do not require an additional power conversion system.

[0075] In some embodiments, the power grid 85 is optional. Power can be discharged to other components that require electrical power.

[0076] The controller 60 can be connected to other components in wired or wireless mode. Figure 1 In the exemplary system 100 shown, controller 60 can be connected to other components such as converter 10, BPMU 30, and EMS 110 via data cable or wireless connection 22. BPMU 30 can also be connected to battery pack 20 via data cable or wireless connection 22. Controller 60 can operate in a cloud-based mode.

[0077] Each battery pack 20 can be connected to the power converter 10 (or an independent DC port on the converter 10) via a set of automatic DC circuit breakers (not shown), which activate and control the connection between the battery pack 20 and the converter 10. The converter 10 controls whether to charge or discharge the individual EV battery pack 20 by following instructions from the controller 60.

[0078] refer to Figure 2 The controller 60 includes one or more processors 62 and at least one tangible, non-transitory machine-readable medium encoded with one or more programs configured to perform steps for controlling the discharge process of a system having multiple battery packs. The controller 60, processor 62, and / or program 74 may be external devices to the converter 10 or internal devices within the converter 10.

[0079] One or more processors 62 may include a central controller 64, which includes a parameter input module 66, a model module 68, a parameter control module 70, and an information and instruction module 72. The parameter input module 66 is coordinated with the battery pack 20 and optionally with the BPMU 30 and HMI or EMS 110 to read data from the battery pack 20 and power demand from the HMI or EMS 110. The parameter input module 66 is also coordinated with each power converter 10. The parameter control module 70 is coordinated with each power converter 10 and each battery pack 20, and optionally with the BPMU 30 and HMI or EMS 110 to control the discharge process. Together with one or more programs 74, the model module 68 is configured to perform simulations based on input parameters to provide information and instructions to the parameter control module 70 and the information and instruction module 72. The processor 62 may optionally be connected to one or more displays 76 for displaying information and instructions from the module 72 and for presentation to the operator.

[0080] A controller 60 and processor 62 with program 74 are configured to perform discharge or charge steps as described herein. As shown in Figures 5-6, in some embodiments, the controller 60 is configured to perform steps including: receiving the total power demand (D) to be dispatched from system 100; collecting characteristic data for each battery pack 20 to establish a first voltage-charge curve for each battery pack 20; determining the voltage gradient of each battery pack based on the first voltage-charge curve; and changing the charge and voltage of the corresponding battery pack 20 to control and / or reduce the corresponding voltage gradient of each battery pack to below a predetermined threshold (ε) in a second voltage-charge curve. This step also includes: calculating a corresponding discharge share for each battery pack 20 based on the charge and voltage in the second voltage-charge curve of each battery pack 20 and the total power demand to be dispatched; and providing signals with instructions to the plurality of battery packs 20 and one or more power converters 10 to release power from the plurality of battery packs 20 and / or keep a particular battery pack idle based on the corresponding discharge share or rate of each battery pack. The discharge or dispatch share refers to the percentage of power or energy discharged by a battery pack in the power demand (D). Discharge or dispatch rate refers to the amount of electricity or energy discharged per unit time.

[0081] When the calculated discharge share or rate of a particular battery pack is approximately zero, or when the battery cannot be used to discharge to meet the required conditions, the particular battery pack remains idle and does not discharge. This battery pack may need to be charged or replaced first.

[0082] In some embodiments, the step of changing the charge and voltage of a corresponding battery pack 20 to control and / or reduce the corresponding voltage gradient includes the following steps: identifying the maximum voltage gradient among a plurality of battery packs and the corresponding first battery pack, and reducing or minimizing the maximum voltage gradient of the corresponding first battery pack to below a predetermined threshold (ε) by changing its charge and corresponding voltage. It is assumed that the plurality of battery packs 20 are used for discharge and power dispatch. Then, the steps of identifying and minimizing the maximum voltage gradient are repeated among the remaining battery packs of the plurality of battery packs 20 to establish a second voltage-charge curve for each battery pack 20. Thus, a voltage gradient distribution curve is established for each battery pack in the plurality of battery packs 20.

[0083] In some embodiments, the controller 60 is also configured to dynamically control the discharge of multiple battery packs by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

[0084] This invention provides a controller as described herein for controlling the discharge of a system comprising multiple battery packs. The controller is configured to control the discharge of heterogeneous battery packs, for example, in an energy storage system.

[0085] Embodiments of the present invention also provide a method for controlling the discharge of a system comprising multiple battery packs via a controller as described herein. This method is used to schedule battery packs with different health conditions to provide a consistent and persistent scheduling profile. The method relies on voltage gradient-weighted discharge of each battery pack to provide minimal impact on charge throughput while maximizing energy output. Additionally, this improves system management, including the operation of weaker batteries (i.e., batteries exhibiting a sharp voltage drop during normal discharge).

[0086] For most battery chemistry, healthy batteries exhibit a small voltage drop during normal charge or discharge windows. Therefore, the voltage drop during discharge is an indicator of battery health issues. This method relies on using the voltage drop during discharge to dynamically assess the health of the battery pack and utilizes this gradient to bias scheduling from each battery pack. Through the battery pack's lifetime, reduced throughput leads to improved lifetime and performance.

[0087] Figure 3-4 This is used to illustrate the principles of the method and the program used in controller 60.

[0088] refer to Figure 3 The diagram illustrates the voltage versus charge flow curves of an exemplary battery pack during the discharge process. Input parameters can include voltage, current, and time. The charge or charge flow (Q) is calculated from the current and the elapsed time. Voltage is expressed in volts (V), and charge flow is expressed in amperes multiplied by hours (Ah) or coulombs. Figure 3 As shown, Vmax is the voltage of such a battery pack when it is fully charged or at its maximum permissible charge level. Vmin is the voltage of such a battery pack when it is depleted of charge or reaches its minimum permissible charge level.

[0089] The voltage-charge curve can be empirically generated at a constant discharge level while monitoring the current during the discharge cycle until the voltage drop exceeds a user-defined minimum limit (Vmin), such as... Figure 3 The vertical dashed line in the diagram illustrates this. Current and voltage follow the same or similar trends as charging time increases. Different discharge rates can produce different voltage-to-discharge profiles for the same battery pack. When the voltage drops more than Vmin during discharge, this battery pack exhibits a significantly higher voltage gradient and depletes more quickly. The parameter V*, defined as (V-Vmin) / (Vmax-Vmin), is an indicator of the battery's discharge capacity. This parameter varies from 0 to 1. The higher the parameter, the greater the extent to which the battery pack can discharge.

[0090] Reference Figure 4 voltage gradient Defined by equation (1):

[0091]

[0092] The voltage gradient is the voltage drop divided by the corresponding discharge amount of the battery pack. This is an indicator of the impact of discharge on the remaining battery capacity. A smaller value is considered better. In a general expression, the voltage gradient, or the gradient of the battery voltage, is defined by the following equation (2):

[0093]

[0094] Where ΔQ i It is the discharge from the i-th battery pack, and ΔV i This is the voltage drop that it causes.

[0095] Heterogeneous battery packs exhibit varying voltage-charge-time characteristics. In the method provided in this embodiment, the algorithm biases discharge to battery packs exhibiting lower voltage-over-charge gradients. In other words, one objective is to minimize the gradient of battery voltages as defined in equations (1) or (2). Battery packs with lower voltage gradients are used for discharge with higher priority. For each battery pack, the controller 60 is configured to iteratively select the optimal discharge amount (e.g., Q2 or ΔQ), which translates into a discharge share (Ω) in the overall system's power demand (D). i In order to reduce and / or control the voltage gradient. The voltage gradient of each battery pack is minimized. This effect of a low voltage gradient is additive across all heterogeneous battery packs in the system. This ensures better stability of the same charge throughput while making it easier to meet dispatch power commands delivered to a system with multiple battery packs.

[0096] Use equation (3) to calculate the discharge share (Ω) in the total power demand (D) of the battery pack. i ):

[0097]

[0098] Total electricity demand (D) is the total energy required per unit time. V is the voltage level within the minimum interval from V1 to V2. Q2-Q1 is the discharge (ΔQ). The discharge share can be expressed as a percentage and can be converted into the corresponding discharge rate based on the unit time and the corresponding discharge amount.

[0099] Figure 4 This demonstrates how to iteratively calculate the scheduling share (Ω). i To minimize the voltage gradient while satisfying scheduling constraints, a new Q2 is selected in each iteration, and a new Ω is calculated. i until all total Minimize. The following equations define the model and constraints.

[0100] For multiple battery packs in the system (a total of n battery packs), the sum of the discharge shares is equal to 1, as shown in equation (4):

[0101]

[0102] The operation of reducing the voltage gradient of each battery pack can be iterated multiple times at different time intervals. The corresponding voltage gradient under a certain number of iterations can be calculated using equation (5):

[0103]

[0104] Equation (5) applies to the i-th battery pack and the k-th iteration. The discharge share of the battery pack at a specific time can be calculated using equation (6):

[0105]

[0106] Equation (6) applies to the i-th battery pack at time j. For multiple battery packs, the total discharge equals the total power demand (D), as shown in equation (7):

[0107]

[0108] Equations (5) and (6) indicate the method for calculating the scheduling of each battery pack. In some embodiments, the maximum scheduling (discharge) for each battery is identified. Equation (7) or Equation (4) indicates the scheduling constraints. Discharge energy is assumed to be delivered per unit time. Therefore, for scheduling purposes, energy is synonymous with electricity. Output parameters include the discharge share or rate for each battery pack.

[0109] System 100 includes a heterogeneous battery pack 20 integrated with a bidirectional converter (or inverter) 10 connected to a power grid or microgrid 85, which can be remotely or locally scheduled using intelligent algorithms running in a local or cloud-based controller 60. It is assumed that a data aggregation system for activating / collecting data from the battery pack exists, but this is not required.

[0110] In some embodiments, the algorithm requires prior knowledge of the voltage-charge gradient curve, which can be acquired during trial operation and subsequently updated as the battery pack ages or wears out due to use / non-use.

[0111] Figures 5A-5B An exemplary method 200 for discharging multiple battery packs 20 in a system 100 according to some embodiments is shown. The multiple battery packs 20 are, for example, heterogeneous battery packs selected from new batteries, secondary EV batteries, or combinations thereof. The multiple battery packs 20 are connected in parallel, in series, or in combination thereof.

[0112] refer to Figure 5A In step 202, controller 60 receives the total power demand that needs to be dispatched from system 100. As described herein, the total power demand can be received from EMS 110.

[0113] In step 204, characteristic data for each battery pack 20 are collected to establish a first voltage-charge curve for each battery pack 20. The voltage and charge in this curve can be referred to as the first set of values ​​or initial values. As described above, Figure 3 An exemplary curve is shown. The voltage-charge (Amp-hr) characteristics of each battery pack can be obtained empirically or derived for a set of frequently encountered discharge rates. This provides a family of curves that can be used to track the voltage trajectory of the battery pack for a given scheduling event.

[0114] In step 206, the voltage gradient of each battery pack 20 is determined based on the first voltage-charge curve. For example... Figure 4 As described above, equations (1) or (2) can be used to calculate the voltage gradient.

[0115] In step 210, by changing the charge and corresponding voltage of each battery pack, the voltage gradient of each battery pack can be controlled and / or reduced below a predetermined threshold (ε). This charge and voltage, compared to the initial values, can be referred to as the second charge and the second voltage, which provides a second voltage-charge curve. The resulting voltage gradient can be referred to as the second or final voltage gradient.

[0116] In some embodiments, step 210 for controlling and / or reducing the corresponding voltage gradient of each battery pack includes, as follows: Figure 5B Steps 222, 224, and 226 are shown.

[0117] In step 222, it is assumed that all the plurality of battery packs 20 in system 100 are used for discharging and power dispatching. The maximum voltage gradient and the corresponding first battery pack are identified among the plurality of battery packs.

[0118] In step 224, by changing its charge and corresponding voltage, the maximum voltage gradient of the corresponding first battery pack is reduced or minimized. For example, in some embodiments, the voltage gradient is controlled to be below a predetermined threshold (ε).

[0119] In step 226, the steps of identifying the maximum voltage gradient and minimizing the maximum voltage gradient (steps 222 and 224) are then repeated among the remaining cells in the plurality of battery packs 20 to establish a second voltage-charge curve for each battery pack. Figure 4 Equations (5), (6) and (7) can be used.

[0120] The predetermined threshold (ε) can be any suitable value based on the battery pack type. For example... Figure 3 As shown, the appropriate discharge range is in the range of Vmax to Vmin. In some embodiments, when the voltage is volts and the charge is amperes per hour (Ah), the appropriate predetermined threshold (ε) may be in the range of less than 2, for example 0-1.5, 0-1, 0-0.5.

[0121] Return to reference Figure 5A In step 212, the corresponding discharge share of each battery pack is calculated based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand that needs to be dispatched. Equation (3) or (6) can be used as described above.

[0122] In step 214, power is released from the multiple battery packs based on the corresponding discharge share of each battery pack. Instructions are sent from the controller 60 to each battery pack 20 and / or one or more converters 10 connected to the multiple battery packs 20 to discharge based on the corresponding discharge share of each battery pack 20. In some embodiments, if the corresponding discharge share of a particular battery pack 20 is approximately zero, or if it cannot be used under certain conditions, that particular battery pack 20 may remain idle.

[0123] In some embodiments, the discharge process of multiple battery packs is dynamically controlled by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

[0124] refer to Figure 6 Exemplary block diagram 300 illustrates the steps and algorithms used according to method 200 in some embodiments. Each block represents a step or criterion.

[0125] In block 302 or step 302, the total power demand (i.e., the total dispatch level) (D) is received. In block 304, the voltage-charge characteristics of each battery pack are obtained or derived for a set of frequently encountered discharge rates. For multiple (n) battery packs in system 100, a family (N) of such curves will be obtained. In block 306, the dispatch distribution among all the multiple battery packs is assumed.

[0126] In box 308, the voltage gradient of each battery pack in the curve is calculated. In box 310, a voltage gradient distribution map of all battery packs is created, and the battery pack with the maximum voltage gradient is identified. Furthermore, the voltage gradient is reduced to a suitable level for discharge, which also benefits battery life. By changing the charge and corresponding voltage based on the curve obtained in box 304, the maximum voltage gradient is reduced or minimized below a specific threshold (ε). In box 312, if the voltage gradient of such a battery is reduced or minimized below the specific threshold (ε), the battery pack is targeted for a scheduling share or rate (…). Figure 5AStep 212) is assigned. The process from box 306 to box 312 can be repeated cyclically. Figure 5A Step 210 and Figure 5B Steps 222 to 226). This method is used to reduce the gradient of other battery packs unless they fall below a threshold (ε), maintaining the scheduling constraints as shown in equation (7). In other words, the program in controller 60 searches for a combination of discharge rates such that Below the threshold (ε).

[0127] As output, a scheduling share is allocated to each individual cell and each battery pack. If the discharge rate changes, an alternative curve is used to generate the voltage distribution.

[0128] like Figure 6 As shown, in some embodiments, after the battery pack management system obtains the scheduled energy demand, an initial distribution of scheduling is assumed among the battery packs. By redistributing the scheduling among the battery packs while maintaining a fixed total scheduling, the maximum gradient is minimized to below a user-defined parameter (ε). Once the maximum voltage gradient is minimized, the scheduling energy for each battery pack is calculated. Even if a battery pack is large, its scheduling energy may be low due to the high voltage gradient. Conversely, if a smaller battery has a lower voltage gradient, the scheduling energy from that smaller battery may be higher. In any case, the program in controller 60 ensures that the maximum scheduling capacity of each battery pack is never violated.

[0129] In certain situations, under conditions of a significant voltage drop, battery pack-specific time constraints can be used to force a particular battery pack to schedule or stop discharging at a faster or slower rate. In some embodiments, to mitigate abrupt changes in the scheduling distribution within the battery pack due to voltage variations, a windowed average (rather than instantaneous) can be used to calculate Ω. i :

[0130]

[0131] In some embodiments, to reduce fluctuations caused by rapid voltage curve shifts, window averaging can be applied to calculate the average voltage over a predefined shift window.

[0132] like Figure 6 As shown, these steps are repeated for each new schedule.

[0133] All battery packs need to be cycled at different discharge rates to obtain characteristic profiles. Most battery systems collect (or provide) voltage and current readings. These are used to calculate charge and energy flow.

[0134] Figure 7Two exemplary battery packs, battery pack A and battery pack B, are shown, with different voltage-charge characteristics scheduled by the procedures and algorithms provided in this embodiment of the invention. Both battery packs are of the same brand.

[0135] Figure 8 The diagram illustrates the power distribution of two exemplary battery packs over time. The power demand is 6000 watts. Dashed lines A1 and B1 show identical battery packs using existing technology, where both packs initially discharge at nearly the same rate until the weaker pack A fails and pack B must perform all the discharge requirements. Discharging in this manner results in significant stress and degradation in both battery packs.

[0136] Lines A2 and B2 illustrate a novel trajectory based on the controller and method provided in this embodiment of the invention, demonstrating the performance of the battery pack. This method manages the proportional share of scheduling based on voltage differences. Battery pack A, with a lower voltage, is scheduled with a lower power share. Reduced discharge results in lower degradation and better balancing performance between battery packs.

[0137] The systems, controllers, and methods provided in these embodiments offer numerous advantages. For example, various battery packs of different qualities can be used, such as used EV battery packs. Pre-selection or removal of battery packs is not required. If a battery pack and / or a converter fails to respond, the system still has the ability to supply power to the load to meet power demands. The systems, controllers, and methods extend the lifespan of each battery pack, and they also provide flexibility for maintaining and upgrading the system.

[0138] The methods and systems described herein can be embodied, at least in part, in the form of computer-implemented processes and apparatus for performing these processes. The disclosed methods can also be embodied, at least in part, in the form of a tangible, non-transitory, machine-readable storage medium encoded with computer program code. The medium may include, for example, RAM, ROM, CD-ROM, DVD-ROM, BD-ROM, hard disk drive, flash memory, or any other non-transitory machine-readable storage medium or any combination of these media, wherein the computer becomes an apparatus for performing the method when the computer program code is loaded into and executed by the computer. The methods can also be embodied, at least in part, in the form of a computer, in which computer program code is loaded into and / or executed, such that the computer becomes an apparatus for performing the methods. When implemented on a general-purpose processor, computer program code segments configure the processor to create specific logic circuits. The methods can optionally be embodied, at least in part, in a digital signal processor formed by an application-specific integrated circuit for performing the methods. The computer or control unit can be operated remotely using a cloud-based system.

[0139] Although the subject matter has been described with reference to exemplary embodiments, it is not limited thereto. Rather, the appended claims should be interpreted broadly to include other variations and embodiments that may be made by those skilled in the art.

Claims

1. A method for controlling the discharge of a battery pack, characterized in that, The method includes: The total power demand required to receive the signal; Collect characteristic data for each of the multiple battery packs to establish a first voltage-charge curve for each battery pack; The voltage gradient of each battery pack is determined based on the first voltage-charge curve. The voltage gradient of each battery pack is controlled to be below a predetermined threshold by changing the charge and corresponding voltage of the corresponding battery pack, and a second voltage-charge curve is established based on the changed charge and voltage. Based on the charge and voltage in the second voltage-charge curve of each battery pack and the total power demand, calculate the corresponding discharge share of each battery pack; and Based on the corresponding discharge share of each battery pack, control the discharge of the plurality of battery packs and / or control a particular battery pack to remain idle; The discharge share of each battery pack is calculated using the following formula: ； In the formula, Let represent the discharge share of the i-th battery pack, D represent the total power demand, V represent the voltage level in the minimum interval from voltage V1 to voltage V2 in the second voltage-charge curve, and Q2-Q1 represent the discharge amount from charge Q2 to charge Q1 corresponding to the minimum interval.

2. The method according to claim 1, characterized in that, Controlling the voltage gradient of each battery pack to be below a predetermined threshold includes the following steps: Identify the maximum voltage gradient and the corresponding first battery pack among the plurality of battery packs; By changing the charge and corresponding voltage of the corresponding first battery pack, the maximum voltage gradient of the corresponding first battery pack is minimized to below the predetermined threshold. as well as The identification and minimization steps are repeated in the remaining battery packs among the plurality of battery packs to establish a second voltage-charge curve for each battery pack.

3. The method according to claim 1, characterized in that, The control of keeping a specific battery pack idle includes: When the corresponding discharge share of a particular battery pack approaches zero, the particular battery pack is kept idle.

4. The method according to claim 1, characterized in that, The multiple battery packs are heterogeneous battery packs, and the heterogeneous battery packs are formed by new batteries, secondary power batteries, or a combination of both.

5. The method according to claim 1, characterized in that, The multiple battery packs are configured to be connected in parallel, in series, or in a combination of both.

6. The method according to any one of claims 1 to 5, characterized in that, The control of the discharge of the plurality of battery packs includes: The discharge of the multiple battery packs is dynamically controlled by instantaneously updating the corresponding discharge share or rate of each battery pack over time.

7. A controller for controlling the discharge of a battery pack, characterized in that, The method includes one or more processors and at least one machine-readable storage medium encoded with one or more programs, wherein the processor is configured to execute the one or more programs to implement the method of any one of claims 1 to 6.

8. The controller according to claim 7, characterized in that, The controller is configured to control the plurality of battery packs to release power to the grid or load.

9. A system for controlling the discharge of a battery pack, characterized in that, The system includes: Multiple battery packs; One or more power converters, each power converter coupled to at least one of the plurality of battery packs and configured to perform AC-DC conversion on the output current of the battery packs; and The controller of claim 7 or 8, coupled to the plurality of battery packs and the one or more power converters, for controlling the discharge of the plurality of battery packs and / or controlling a particular battery pack to remain idle.

10. The system according to claim 9, characterized in that, The system also includes one or more Battery Power Management Units (BPMUs), each BPMU being connected to one or more battery packs and configured to monitor the one or more battery packs and provide characteristic data of the one or more battery packs to the controller.

11. The system according to claim 9, characterized in that, The system is an electric energy storage system, and the total power demand is configured to be received from the upper-level energy management system.

12. A machine-readable storage medium having instructions stored thereon for causing a machine to perform the method of any one of claims 1 to 6.

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