Method of implementing opportunistic battery capacity algorithm for system having multiple sub-packets

Abstract

An electrical system and method of operation are disclosed. The electrical system may be an energy storage device that operates a load. The battery pack provides power to the electrical system. The processor determines a model of power scheduling of the electrical system, determines a test time during operation of the electrical system using the model for obtaining a parameter suitable for calculating a capacity of the battery pack, obtains the parameter of the battery pack at the test time, calculates the capacity of the battery pack using the parameter, and displays the calculated capacity of the battery pack. And operating the electrical system based on the calculated capacity.

Description

Technical Field

[0001] The present disclosure relates to diagnosing an electrical system during operation, and more particularly, to systems and methods for determining the capacity of a power supply of an electrical system during its operation. Background Art

[0002] Various electrical systems are used in scenarios where the system operates continuously or nearly continuously. Examples of such electrical systems include land and sea vehicles utilizing electric or hybrid-electric propulsion devices (electric trains, electric ferries, etc.) and stationary energy storage systems, among others. To maintain the system, various diagnostics need to be performed. However, many diagnostic operations, such as calculating the capacity of the power supply of an electrical system, require electrically disconnecting the subsystem. Therefore, for these systems operating continuously or nearly continuously, it is not possible to perform such diagnostic operations. Accordingly, it is desirable to provide a system and method by which the capacity of the power supply can be determined without interrupting the operation of the electrical system. Summary of the Invention

[0003] In one exemplary embodiment, a method of operating an electrical system is disclosed. A model of the power scheduling of the electrical system is determined, and the electrical system is powered by a battery pack for operation. The model is used to determine a test time during the operation of the electrical system to obtain parameters suitable for calculating the capacity of the battery pack. The parameters of the battery pack are obtained at the test time. The capacity of the battery pack is calculated using the parameters. The electrical system is operated based on the calculated capacity.

[0004] In addition to one or more features described herein, the method further includes obtaining the parameters using a data collection process that is either an interruption of the operation of the electrical system or an uninterrupted operation of the electrical system.

[0005] In addition to one or more features described herein, the method further includes obtaining the parameters by disconnecting a contactor between the battery pack and the electrical system and determining the state of charge in the case of the contactor being disconnected.

[0006] In addition to one or more features described herein, the battery pack is selected from a plurality of battery packs, and further includes isolating the selected battery pack and obtaining the parameters of the selected battery pack while operating the electrical system using a non-isolated battery pack.

[0007] In addition to one or more features described herein, the method further includes operating the electrical system at a constant current, obtaining a first measurement of voltage, determining the current throughput of the battery pack, and obtaining a second measurement of voltage.

[0008] In addition to one or more features described herein, the constant current is approximately zero amperes. [[ID=30]]

[0009] In addition to one or more of the features described herein, the method further includes selecting the test time from the model based on at least one of: Global Positioning System (GPS) telemetry, the time or distance the electrical system travels without a predicted change in elevation, the time or distance the electrical system travels without a predicted stop, and the time or distance the electrical system travels without a predicted change in the load of the battery pack.

[0010] In another exemplary embodiment, an electrical system is disclosed. The electrical system includes a battery pack that provides power to the electrical system and a processor. The processor is configured to determine a model of the power schedule of the electrical system, use the model to determine a test time during operation of the electrical system for obtaining parameters suitable for calculating the capacity of the battery pack, obtain the parameters of the battery pack at the test time, calculate the capacity of the battery pack using the parameters, and operate the electrical system based on the calculated capacity.

[0011] In addition to one or more of the features described herein, the processor is further configured to obtain the parameters using a data collection process that is either an interruption of the operation of the electrical system or a non - interruption of the operation of the electrical system.

[0012] In addition to one or more of the features described herein, the processor is further configured to obtain the parameters by disconnecting a contactor between the battery pack and the electrical system and determining the state of charge in the case where the contactor is disconnected.

[0013] In addition to one or more of the features described herein, the processor is further configured to select a battery pack from a plurality of battery packs, isolate the selected battery pack, and obtain the parameters of the selected battery pack while operating the electrical system using a non - isolated battery pack.

[0014] In addition to one or more of the features described herein, the processor is further configured to operate the electrical system at a constant current, obtain a first measurement of voltage, determine the current throughput of the battery pack, and obtain a second measurement of voltage.

[0015] In addition to one or more of the features described herein, the constant current is approximately zero amperes.

[0016] In addition to one or more of the features described herein, the processor is further configured to select the test time from the model based on at least one of: Global Positioning System (GPS) telemetry, the time or distance the electrical system travels without a predicted change in elevation, the time or distance the electrical system travels without a predicted stop, and the time or distance the electrical system travels without a predicted change in the load of the battery pack.

[0017] In yet another exemplary embodiment, an energy storage device for operating a load is disclosed. The energy storage device includes a battery pack that provides power to the load and a processor. The processor is configured to determine a model of the power schedule of the energy storage device, use the model to determine a test time during operation of the energy storage device for obtaining parameters suitable for calculating the capacity of the battery pack, obtain parameters of the battery pack at the test time, calculate the capacity of the battery pack using the parameters, and operate the energy storage device based on the calculated capacity.

[0018] In addition to one or more of the features described herein, the processor is further configured to obtain the parameters using a data collection process that is one of an interruption of the operation of the energy storage device and a non-interruption of the operation of the energy storage device.

[0019] In addition to one or more of the features described herein, the processor is further configured to obtain the parameters by disconnecting a contactor between the battery pack and the load and determining the state of charge when the contactor is disconnected.

[0020] In addition to one or more of the features described herein, the processor is further configured to select a battery pack from a plurality of battery packs, isolate the selected battery pack, and obtain parameters of the selected battery pack while operating the load using a non-isolated battery pack.

[0021] In addition to one or more of the features described herein, the processor is further configured to operate the energy storage device at a constant current, obtain a first measurement of voltage, determine the current throughput of the battery pack, and obtain a second measurement of voltage.

[0022] In addition to one or more of the features described herein, the constant current is approximately zero amperes.

[0023] The above features and advantages of the present disclosure, as well as other features and advantages, are apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, in which:

[0025] Figure 1 is a diagnostic system for diagnosing an electrical system in an illustrative embodiment;

[0026] Figure 2 is a graph of the power schedule of an electrical system over time in an illustrative embodiment;

[0027] Figure 3is a flowchart of a method for selecting a method for data collection at an electrical system to determine a battery pack capacity;

[0028] Figure 4 is a flowchart of a method for testing an embodiment in a battery pack;

[0029] Figure 5 is a flowchart of a method for determining an embodiment capacity in another battery pack; and

[0030] Figure 6 is a flowchart of a method for testing a battery pack that is one of a plurality of battery packs of an electrical system. DETAILED DESCRIPTION

[0031] The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0032] Figure 1 is a diagnostic system 100 for diagnosing an electrical system 102 in an illustrative embodiment. The electrical system 102 includes a power source 104, an electric motor 106, and a load 108, which may be a mechanical load, a non - mechanical load, an electrical load, etc. The electric motor 106 is powered by the power source 104 to operate the load 108. The electrical system 102 operates continuously or nearly continuously such that the system is in use for a high percentage of the time. The period of operation of the electrical system 102 is typically greater than the time between required diagnostic checks. In various embodiments, the electrical system 102 can be an electric vehicle, such as an electric train, an electric aircraft, an electric cargo ship, an electric ferry, a stationary energy storage device, or other systems designed for industrial, residential, and commercial use.

[0033] The power source 104 includes one or more battery packs, which may be rechargeable energy storage sources (RESS). Each battery pack may include a plurality of sub - packs. For illustrative purposes only, the power source 104 includes a first battery pack 110a, a second battery pack 110b, and a third battery pack 110c. Each battery pack is coupled to the electric motor 106 via an associated switch or contactor. For example, the first battery pack 110a is coupled via a first contactor 112a, the second battery pack 110b is coupled via a second contactor 112b, and the third battery pack 110c is coupled via a third contactor 112c. Each battery pack also has an associated sensor that obtains various parameters indicative of the capacity of the battery pack. By way of example, a first sensor 114a is associated with the first battery pack 110a, a second sensor 114b is associated with the second battery pack 110b, and a third sensor 114c is associated with the third battery pack 110c. The sensors may include a voltmeter, an ammeter, etc.

[0034] The controller 116 controls the operation of the contactors 112a, 112b, 112c and obtains measurement results from the sensors 114a, 114b, 114c. The controller 116 may include processing circuitry, which may include an application specific integrated circuit (ASIC), electronic circuitry, a processor (shared, dedicated, or group) that executes one or more software or firmware programs, and memory, combinational logic circuitry, and / or other suitable components that provide the described functionality. According to one or more embodiments detailed herein, the controller 116 may include a non-transitory computer-readable medium storing instructions that, when processed by one or more processors of the controller 116, implement a method of obtaining parameters of a battery pack during operation of an electrical system for diagnostic purposes.

[0035] The controller 116 communicates with a remote server 120. The controller 116 may similarly be used to schedule operations for obtaining parameters of the battery pack of the electrical system 102. The remote server 120 stores a model of the operation schedule of the electrical system 102 and transmits a signal to the controller 116 based on the model, causing the controller to perform diagnostic operations on the power supply 104. The controller 116 may transmit the collected data to the remote server 120. The controller 116 and / or the remote server 120 may calculate the capacity of one or more battery packs based on the collected data. Based on these capacity calculations, the remote server 120 may send a signal to the charging station 122 to schedule a charging operation. The remote server 120 may also send a signal to the controller 116 to indicate the scheduled charging.

[0036] Figure 2FIG. 200 is a graph showing the power scheduling of the electrical system 102 in the illustrative embodiment over time. Time (t) is shown along the abscissa, and power (P) is shown as a percentage of full power along the ordinate axis. The curve 202 representing the power scheduling shows the power used by the electrical system 102 over time. The curve 202 includes high operating power periods 204a - 204g during high power usage of the electrical system 102 and low operating power periods 206a - 206g during periods when the electrical system 102 is stationary or nearly stationary. The curve 202 shows that the electrical system 102 uses power almost constantly and has very few interruptions. Additionally, each interruption (e.g., low operating power periods 206a - 206g) is relatively short compared to the high operating power periods 204a - 204g. During the high operating power periods 204a - 204g, the electrical system 102 can operate at 100% power capacity (e.g., high operating power periods 204a - 204e and 204g) or at near 100% power capacity (e.g., low operating power period 204f). The low operating power periods 206a - 206g can include periods when the electrical system 102 is turned off (e.g., low operating power periods 206a, 206c, 206d, 206e, and 206g) or periods when the electrical system operates at a low level, idle, etc. (e.g., low operating power periods 206b and 206f). The durations of the high operating power periods can be uniform. As Figure 2 shown, the high operating power periods 204a - 204g are non - uniform, for example, as shown by high operating power periods 204d and 204e.

[0037] The shape of the curve 202 (i.e., the power scheduling) can be affected by multiple parameters. For example, the power scheduling of an electric train can be affected by parameters such as the position of the train, the cargo load, the change in train elevation over a given distance, the distance between train stops, weather conditions (e.g., temperature, precipitation), etc.

[0038] In various embodiments, these parameters can be used to develop a model of the power scheduling. The model can be stored at the remote server 120 and can be used to determine the appropriate times at which the parameters can be measured. The model can predict the future usage patterns of the electrical system 102, which can be used to select the times for data collection. This can be useful when the power scheduling is not a preset schedule but is determined by external parameters. For example, weather forecasts can be used in conjunction with the model to determine the best times for obtaining measurements. Alternatively, when the electrical system has a preset power scheduling, the model can reflect that schedule.

[0039] Figure 3FIG. 300 is a flow chart of a method for selecting data collection at an electrical system 102 to determine battery pack capacity. The method begins at block 302. At block 304, a decision is made as to whether an update to the battery capacity calculation is needed while the electrical system 102 is in operation. If a capacity update is not needed, the method proceeds to block 306. At block 306, the electrical system 102 operates normally, where parameters of the electrical system 102 are obtained using standard methods when the electrical system is stationary. The method proceeds from block 306 to block 320. At block 320, the capacity of the battery is calculated using the obtained parameters.

[0040] Returning to block 304, if a capacity calculation update is needed (while the electrical system 102 is operating), the method proceeds to block 308. At block 308, a model of the power schedule is retrieved and used to determine the future use of the electrical system 102. At block 310, one or more test times are selected from the model for a given constraint. In one embodiment, the constraint includes time, and the test times are selected to be executed within a given time frame (Δt). In another embodiment, the constraint includes mileage, and the test times are selected to be executed before the electrical system travels a given number of miles (Δx). In yet another embodiment, the constraint includes current throughput, and the test times are selected to be executed before the electrical system experiences a given current throughput (ΔA).

[0041] The test times can be selected based on various parameters. As an example, for an electric train, the time or distance traveled can be selected such that there is no predicted change in train elevation, no predicted stops of the train, no predicted change in train load, etc. The test times can be selected based on the position of the train, which can be obtained from Global Positioning Satellite (GPS) data. The position of the train can be used to predict a window of time with little or no elevation change, no stops, no additional load, etc. At block 312, a method for measuring the parameters for capacity calculation is selected.

[0042] At block 314, it is determined whether the measurement process can be performed at the test times without interrupting the operation of the electrical system 102. If a process that does not interrupt the operation of the electrical system 102 can be selected, the method proceeds to block 316. At block 316, a non-interrupt process is performed to obtain the parameters. Returning to block 314, if the non-interrupt process is not available, the method proceeds to block 318. At block 318, an interrupt process is performed to obtain the parameters during the operation of the electrical system 102. The selected process can be the least interruptive or least invasive process of the operation.

[0043] From block 316 or block 318, the method proceeds to block 320. At block 320, the capacity of the battery is updated using the obtained parameters. The method proceeds from block 320 to block 322, where the method ends.

[0044] Figure 4 FIG. 400 is a flow chart of a method for testing a battery pack in one embodiment. In various embodiments, the method can be used to test a sub-group of the battery pack. In block 402, the contactor between the battery pack and the electric motor is opened to isolate the battery pack from the electric motor. If the contactor is already open, closing of the contactor is prevented. In block 404, with the battery pack isolated, a first state of charge (SOC A ) of the battery pack is calculated. In block 406, the contactor is closed. In block 408, when the battery pack is in use (e.g., operating the motor), the current throughput (I accum ) through the battery pack is measured. In block 410, the contactor is opened to isolate the battery pack again. In block 412, a second state of charge (SOC B ) of the battery pack is measured. In block 414, the capacity of the battery pack is determined based on the first state of charge, the second state of charge, and the current throughput, as shown in Equation (1):

[0045]

[0046] The method shown in flow chart 400 can be an interruptive method of data collection. In various embodiments, Figure 4 the method can be used to test a sub-group of the battery pack.

[0047] Figure 5 FIG. 500 is a flow chart of a method for determining the capacity of a battery pack in another embodiment. In block 502, the current through the battery pack is brought to a steady state, such as a steady state where the electrical system 102 is idle or near stationary. In various embodiments, the steady state is zero amperes. In block 504, a first voltage (V A ) of the battery pack is measured. In block 506, the battery is operated at an operating current level. In block 508, the current through the battery pack is again brought to a steady state. In block 510, a second voltage (V B ) of the battery pack is measured. In block 512, the capacity of the battery pack is determined based on the first voltage V A and the second voltage V B . In particular, a first SOC can be determined based on the first voltage V A , and a second SOC can be determined based on the second voltage V B . Then the capacity of the battery pack can be determined, for example, using Equation (1).

[0048] Figure 6FIG. 600 is a flow chart illustrating a method of testing a battery pack, which is one of a plurality of battery packs of an electrical system 102. In block 602, the contactor between the selected battery pack and the load is opened to isolate the selected battery pack from the motor. If the contactor is already open, closing of the contactor is prevented. In block 604, a first state of charge (SOC A ) of the selected battery pack is calculated. In block 606, the contactor of the selected battery pack is closed to reconnect the selected battery pack to the electric motor 106. In block 608, the current throughput (I accum ) through the selected battery pack is measured. In block 610, the contactor is opened to isolate the battery pack again. In block 612, a second state of charge (SOC B ) of the selected battery pack is measured. In block 614, the capacity of the battery pack is determined based on the first state of charge, the second state of charge, and the current throughput. In block 616, the plurality of battery packs are checked to determine whether all the data has been collected. If not all of the battery packs have been tested, the method returns to block 602 and a different battery pack is selected for testing. Otherwise, at block 616, if all of the battery packs have been tested, the method proceeds to block 618, where the method ends. In various embodiments, Figure 6 the method can be used to test sub - groups of battery packs by individually isolating the sub - groups during testing.

[0049] The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. Unless the context clearly dictates otherwise, the term "or" means "and / or." References throughout the specification to "aspect" mean that a particular element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. Additionally, it should be understood that the described elements may be combined in any suitable manner in the various aspects.

[0050] When an element such as a layer, a film, a region, or a substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, no intervening elements are present.

[0051] Unless otherwise stated herein, all test standards are the most current standards in effect as of the filing date of this application, or if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

[0052] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0053] Although the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements thereof can be replaced with equivalents without departing from its scope. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without departing from the basic scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that all embodiments falling within its scope be included.

Claims

1. A method of operating an electrical system, comprising: Determining a model of the power scheduling of the electrical system, the electrical system being powered by a battery pack; Using the model to determine a test time during the operation of the electrical system for obtaining parameters suitable for calculating the capacity of the battery pack; Obtaining the parameters of the battery pack at the test time; Calculating the capacity of the battery pack using the parameters; And Operating the electrical system based on the calculated capacity.

2. The method according to claim 1, further comprising obtaining the parameters by disconnecting a contactor between the battery pack and the electrical system and determining a state of charge in the case where the contactor is disconnected.

3. The method according to claim 2, wherein, The battery pack is selected from a plurality of battery packs, and the method further comprises isolating the selected battery pack and obtaining the parameters of the selected battery pack while operating the electrical system using a non-isolated battery pack.

4. The method according to claim 1, further comprising operating the electrical system at a constant current, obtaining a first measurement of voltage, determining a current throughput of the battery pack, and obtaining a second measurement of voltage.

5. The method according to claim 1, further comprising selecting the test time from the model based on at least one of: (i) global positioning satellite (GPS) telemetry; (ii) a time or distance traveled by the electrical system without a predicted change in altitude; (iii) a time or distance traveled by the electrical system without a predicted stop; and (iv) a time or distance traveled by the electrical system without a predicted change in the load of the battery pack.

6. An electrical system, comprising: A battery pack that provides power to the electrical system; A processor configured to: Determine a model of the power scheduling of the electrical system; Use the model to determine a test time during the operation of the electrical system for obtaining parameters suitable for calculating the capacity of the battery pack; Obtain the parameters of the battery pack at the test time; Calculate the capacity of the battery pack using the parameters; And Operate the electrical system based on the calculated capacity.

7. The electrical system according to claim 6, wherein, The processor is further configured to obtain the parameters by disconnecting a contactor between the battery pack and the electrical system and determining a state of charge in the case where the contactor is disconnected.

8. The electrical system according to claim 7, wherein, The processor is further configured to select a battery pack from a plurality of battery packs, isolate the selected battery pack and obtain the parameters of the selected battery pack while operating the electrical system using a non-isolated battery pack.

9. The electrical system according to claim 6, wherein, The processor is further configured to operate the electrical system at a constant current, obtain a first measurement of voltage, determine a current throughput of the battery pack, and obtain a second measurement of voltage.

10. The electrical system according to claim 6, wherein, The processor is further configured to select the test time from the model based on at least one of the following: (i) Global Positioning Satellite (GPS) telemetry; (ii) the time or distance traveled by the electrical system in the absence of a predicted elevation change; (iii) the time or distance traveled by the electrical system in the absence of a predicted stop; and (iv) the time or distance traveled by the electrical system in the absence of a predicted change in the load of the battery pack.

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