Managing battery state of charge levels on electric machine

Abstract

Various techniques to maintain the same state of charge level between multiple battery strings, manage the use of battery strings during machine idle / low power conditions, and manage the use of battery strings with insufficient state of charge levels.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to energy storage systems for electric machines. BACKGROUND

[0002] Battery electric machines are electric vehicles that rely solely on stored electrical power in battery modules to propel and operate the machine. Unlike hybrid vehicles that combine an internal combustion engine with an electric motor, battery electric machines operate entirely on electrical power, making them an environmentally friendly alternative to gasoline or diesel powered machines. These machines utilize electric motors powered by high capacity battery modules that provide the necessary energy to drive the vehicle's traction system, including wheels and / or tracks, for example.

[0003] Battery modules are the heart of battery electric machines. They are composed of multiple individual battery cells, such as lithium ion or lithium polymer, that store electrical energy chemically. These cells are interconnected and packaged together in a compact and robust unit, ensuring efficient energy storage and delivery. The size and capacity of the battery module varies depending on the particular machine and its intended use. Higher capacity battery modules allow battery electric machines to operate for longer periods of time on a single charge.

[0004] EP2969640B1 describes a system and method for balancing the state of charge between a plurality of energy storage modules in a hybrid electric vehicle. The method includes determining the state of charge of individual energy storage modules of the plurality of energy storage modules operably connected to a power source in a hybrid electric vehicle. The vehicle is operated using a subset of the plurality of energy storage modules when the state of charge of the subset of the plurality of energy storage modules is outside of a tolerance relative to the remaining energy storage modules of the plurality of energy storage modules. The energy storage modules can be charged or discharged using the method in order to balance the state of charge of the energy storage modules. SUMMARY

[0005] The present disclosure describes various techniques to maintain the same state of charge (SOC) level across multiple battery strings, manage battery string usage during machine idle / low power conditions, and manage the usage of battery strings with deficient state of charge levels.

[0006] In some aspects, the present disclosure relates to an electrical system for providing power to at least one traction component and at least one accessory component of an electric machine, the electrical system comprising: a battery system configured to supply power to components of the electric machine, the battery system comprising: a plurality of battery strings, wherein each battery string comprises a battery module having at least one battery cell; an electronic control module configured to receive a representation of a state of charge of each battery string, the electronic control module comprising a control unit configured to: determine which battery string has a highest state of charge; and when the highest state of charge exceeds a state of charge of another battery string by a threshold value, select the battery string having the highest state of charge to provide power to the at least one accessory component based on a load demand of the at least one accessory component; and an output coupled to the battery system and configured to supply power to the at least one accessory component without supplying power to the at least one traction component.

[0007] In some aspects, the present disclosure relates to an electrical system for providing power to at least one traction component and at least one accessory component of an electric machine, the electrical system comprising: a battery system configured to supply power to components of the electric machine, the battery system comprising: a plurality of battery strings, wherein each battery string comprises a battery module having at least one battery cell; an electronic control module configured to receive a representation of a state of charge of each battery string, the electronic control module comprising a control unit configured to: compare a state of charge of a corresponding battery string to a threshold value; when one of the states of charge is below the threshold value, selectively isolate the corresponding battery string so as to prevent the battery string from providing power to the at least one accessory component; and an output coupled to the battery system and configured to supply power to the at least one accessory component without supplying power to the at least one traction component.

[0008] In some aspects, the present disclosure relates to a method for providing power to at least one traction component and at least one accessory component of an electric machine, the method comprising: receiving a representation of a state of charge of each of a plurality of battery strings; determining which battery string has a highest state of charge; and when the highest state of charge exceeds a state of charge of another battery string by a threshold value, selecting the battery string having the highest state of charge to provide power to the at least one accessory component based on a load demand of the at least one accessory component. BRIEF DESCRIPTION OF DRAWINGS

[0009] In the drawings, which are not necessarily drawn to scale, like numerals can describe similar components in different views. Like numerals having different letter suffixes can represent different instances of the like components. The drawings illustrate generally, by way of example, various embodiments discussed in the present document.

[0010] Figure 1 is a perspective view of an example of a battery powered machine in which various techniques of the present disclosure can be implemented.

[0011] Figures 2A-2B is a block diagram depicting an example of an electrical system in which various techniques of the present disclosure can be implemented.

[0012] Figure 3 is a block diagram of an example of an electrical connection between a battery electronic control module and a machine electronic control module.

[0013] Figure 4 is a flowchart of an example of a method for providing power to at least one traction component and at least one accessory component of an electric machine in accordance with the present disclosure. DETAILED DESCRIPTION

[0014] State of Charge (SOC) refers to the current amount of electrical energy stored in a battery, expressed as a percentage of its maximum capacity. SOC represents the intermediate charge level available in the battery at a given time. SOC indicates how much energy is left in the battery, where 0% means the battery is completely discharged and 100% means the battery is completely charged. SOC changes dynamically as the battery discharges or charges. Monitoring SOC is critical for estimating the run time of the battery, determining when to recharge, and preventing over-discharge or over-charge.

[0015] The present inventors have recognized several problems with battery systems. Currently, it is desirable to maintain the SOC of a battery at the same level across battery systems, where a battery system includes one or more battery strings, and where each battery string includes a battery module having at least one battery cell. Furthermore, it is desirable to manage the use of battery strings based on the condition of the machine and the battery. It is also desirable to manage the use of battery strings having a deficient state of charge.

[0016] The present inventors have solved these problems with various techniques described in detail below. The present disclosure describes various techniques to maintain the same SOC level across multiple battery strings, to manage the use of battery strings during machine idle / low power conditions, and to manage the use of battery strings having a deficient state of charge level.

[0017] Figure 1 is a perspective view of an example of an electric machine 100 (at least partially battery powered) in which various techniques of the present disclosure can be implemented. Figure 1A non-limiting view of an electric machine 100, such as in the form of a load-haul-dump (LHD) vehicle for mining, is depicted, including a dump bucket 102, wheels 104, 106, an operator’s cab 108, and a vehicle body 110. The wheels 104, 106 are examples of traction components. In other examples, the electric machine 100 can include traction components other than or instead of wheels, such as one or more tracks.

[0018] The electric machine 100 (e.g., an electric mining truck) also includes an electrical system 112. The electrical system 112 can include a DC power source, including but not limited to one or more battery strings, which can supply power to electric motors and the like. The electric motors can supply rotational power to one or more systems, such as systems configured to operate various hydraulic systems of the dump bucket 102. The electrical system 112 can supply power to at least one traction component (e.g., the wheels 104, 106) and at least one accessory component 114 (e.g., a pump motor, a fan, etc.).

[0019] In some examples, the electric machine 100 can include an electric vehicle, such as a car, truck, motorcycle, bus, etc. Although the techniques of the present disclosure can be particularly suitable for use in battery-powered machines, the techniques can be used in hybrid machines.

[0020] Figures 2A-2B A block diagram of an example of a battery system 200 that can implement various techniques of the present disclosure is depicted. The battery system 200 forms part of the electrical system 112 of the electric machine 100. Figure 1 The battery system 200 is configured to supply power to one or more components of the electric machine 100, such as at least one traction component and / or at least one accessory component of the electric machine 100. Figure 1

[0021] The battery system 200 includes a plurality of battery strings, such as three battery strings 202A-202C. In some examples, there can be more than three battery strings, and in other examples, there can be two battery strings. Each battery string includes one or more battery modules 204 having at least one battery cell 206. The battery modules can be serially joined via an electrical disconnect device 208 (e.g., a fuse). Each battery string (e.g., the battery string 202A) can include a current sensor 210, which can be used to monitor current through the battery string. The battery strings 202B and 202C can be similarly configured, as shown in Figures 2A-2B

[0022] ​​The plurality of battery strings 202A-202C can also include string contactors 212A, 212B to allow individual ones of the plurality of battery strings to be selectively electrically coupled or decoupled from the power module 214A. The power module 214A can include an electronic control module 216 (or ECM 216). The ECM 216 performs various functions to manage the battery system 200, as described below.

[0023] The power module 214A can also include battery pack contactors 218A, 218B that can decouple all of the battery strings 202A-202C. The power module 214A can also include one or more voltage sensors 220-224 to monitor the voltage on each battery string and an electrical bus 226. The power module 214A can also include a pre-charge contactor 228 and a pre-charge resistor 230 that can be used to control inrush current when the battery strings are connected. The power module 214A can also include fuses 232A, 232B to permanently isolate the power module 214A from the plurality of battery strings 202A-202C.

[0024] The ECM 216 is electrically coupled to the battery system 200 and is configured to receive sensed signals, such as voltage and current, and output control signals, such as to control the opening and closing of various contactors. For example, the ECM 216 can output a control signal to open various contactors associated with a particular one of the battery strings 202A-202C, such as to remove the battery string when the ECM 216 determines that the battery string is not healthy, such as when its SOC is too low.

[0025] The ECM 216 is configured to receive a representation of the state of charge of each of the battery strings 202A-202C. In accordance with the present disclosure, to maintain the same SOC level among the plurality of battery strings, the ECM includes a control unit 234 configured to determine which of the plurality of battery strings 202A-202C has the highest state of charge. The control unit 234 is configured to select the battery string with the highest state of charge to provide power to the accessory component based on the load demand of the at least one accessory component when the highest state of charge exceeds the state of charge of another battery string by a threshold value.

[0026] As a non-limiting example, assume for purposes of explanation that battery string 202A has a SOC of 90%, battery string 202B has a SOC of 80%, and battery string 202C has a SOC of 80%. To maintain the same SOC level among the plurality of battery strings 202A-202C, control unit 234 can receive data indicative of the state of charge of each of the plurality of battery strings 202A-202C and determine that battery string 202A has the highest state of charge among the three battery strings. When the highest state of charge exceeds the state of charge of another battery string by a threshold value, control unit 234 can then select the battery string having the highest state of charge to provide power to the accessory components based on the load demand of one or more accessory components (e.g., pumps, fans, etc.).

[0027] For example, assume that the threshold value is 2%, which is the difference or delta between the SOCs of the other battery strings. Control unit 234 can then select battery string 202A to provide power to the accessory components based on the load demand of one or more accessory components because it has the highest state of charge and that state of charge exceeds the state of charge of battery string 202B and / or battery string 202C by the threshold value (a difference of 10% between 90% and 80% exceeds the threshold value of 2%). For example, control unit 234 can use the load demand of the accessory component(s) to select a particular battery string to ensure that the battery string has sufficient SOC available to power the accessory components. For example, control unit 234 can generate and output a command signal to close a contactor corresponding to the battery string having the highest state of charge. In Figures 2A-2B In particular, control unit 234 can generate and output a control signal to close string contactors 212A and 212B to select battery string 202A. Similarly, control unit 234 can generate and output a control signal to open string contactors to deselect battery string 202B, 202C.

[0028] Figure 1 Electrical system 112 of electric machine 100 can include an output 236 coupled to battery system 200 at electrical bus 226, for example, that is configured to supply power to accessory component(s) (e.g., fans, pump motors for hydraulic systems and / or cooling, etc.) without supplying power to traction component(s) (e.g., wheels and / or tracks).

[0029] Figure 1 Electrical system 112 of electric machine 100 can also include a machine ECM 238. ECM 238 can include a control unit 240, and ECM 238 is in electrical communication with ECM 216 via a communication path 242. Machine ECM 238 can estimate the load during normal startup and can monitor the load on the electric machine.

[0030] As an example, the control unit 240 of machine ECM 238 can determine the electrical load of the pump motor using the speed at which the pump motor is running. Control unit 234 is configured to... Figures 2A-2B Various current and voltage sensors within the system receive data representing current and voltage information and / or speed, torque, etc., which can be transmitted to the control unit 240 of the machine ECM 238. The control unit 240 can use the received data to calculate the load requirements of (multiple) accessory components, or use lookup data (or other stored data structures) to determine the load requirements. In other examples, the control unit 234 of the battery ECM can perform the calculation or the lookup.

[0031] If needed, battery ECM 216 can ignore requests from machine ECM 238. If the load is expected to increase, machine ECM 238 can communicate with battery ECM 216 (e.g., for anticipated control). In response, battery ECM 216 can bring all battery strings online, for example, to support increased demand, or determine if one or more battery strings can be taken offline if necessary.

[0032] In some examples, control unit 234 is configured to select all battery strings, such as battery strings 202A-202C, when the highest state of charge (SOC) does not exceed a threshold value for another battery string. In other words, the battery strings are considered sufficiently balanced when the difference (or increment) in SOC between them does not exceed a threshold value.

[0033] Figures 2A-2B The battery system 200 may include one or more additional battery strings, such as multiple battery strings 244, which are similar to battery strings 202A-202C and will not be described in detail for the sake of brevity. The battery system 200 may include a power module 214B electrically connected to the multiple battery strings 244. The power module 214B is similar to power module 214A and will not be described in detail for the sake of brevity. The power module 214B may include an ECM 246 having a control unit 248. The ECM 246 performs various functions to manage the battery system 200, as described with respect to ECM 216 in this disclosure. The ECM 246 is in electrical communication with a machine ECM 238 via communication path 250. Other examples may include additional battery strings and corresponding ECMs.

[0034] ECM 216 and ECM 246 can provide battery string data and other data to machine ECM 238 and receive instructions from it. For example, machine ECM 238 can monitor the accessory load and transmit that information to one or both of ECM 216 and ECM 246 (and any additional ECMs, if present).

[0035] In some examples, if a battery string has a low SOC, e.g., is unhealthy, it can be desirable to prevent that battery string from providing power to accessory components. Control unit 234 can compare the state of charge of the corresponding battery string to a threshold, and when one of the state of charge is below the threshold, selectively isolate the corresponding battery string so as to prevent that battery string from providing power to the accessory component(s).

[0036] As a non-limiting example, for purposes of explanation, assume that battery string 202A has a SOC of 10%, battery string 202B has a SOC of 80%, and battery string 202C has a SOC of 80%. Assume that the threshold is 20%, which is the SOC level. Control unit 234 can receive data representative of the state of charge of each of the plurality of battery strings 202A-202C, and compare the SOC to the threshold, e.g., 20%. Because the SOC of battery string 202A (10%) is below the threshold (20%), control unit 234 can generate and output a signal to open the corresponding string contactors 212A, 212B to selectively isolate battery string 202A.

[0037] Figure 3 is a block diagram of an example of an electrical connection between a battery electronic control module and a machine electronic control module. As seen in Figure 3 Machine ECM 238 (of Figures 2A-2B is in electrical communication with ECM 216 (of Figures 2A-2B via a first communication bus 300. Battery ECM is in electrical communication with ECM 246 (of Figures 2A-2B and additional ECMs 302, 304 via a second communication bus 306. Although depicted as a daisy chain configuration, the battery ECM and machine ECM can be electrically coupled in other configurations.

[0038] Figure 4 is a flowchart of an example of a method 400 for providing power to at least one traction component and at least one accessory component of an electric machine, in accordance with the present disclosure. In block 402, method 400 receives a representation of a state of charge of each of a plurality of battery strings. In block 404, method 400 determines which battery string has a highest state of charge. In block 406, method 400, when the highest state of charge exceeds the state of charge of another battery string by a threshold, selects the battery string having the highest state of charge to provide power to the at least one accessory component based on a load demand of the at least one accessory component.

[0039] Industrial applicability

[0040] The present invention relates to techniques for monitoring and managing the state of charge (SOC) of a battery system, with clear industrial applicability. As described, SOC represents the current charge level of a battery, and is critical for estimating run time, scheduling recharging, and preventing over-discharge / over-charge. The ability to monitor and control SOC provides practical benefits for optimizing battery usage and extending battery life.

[0041] The present invention provides solutions for deficiencies in existing battery systems by maintaining consistent SOC levels between battery strings, managing string usage during low power conditions, and regulating strings with deficient SOC. These techniques have clear real-world applications for improving battery management in a variety of systems, including electric machines.

[0042] In summary, the described invention provides advancements in battery monitoring and control techniques, with clear industrial use. These techniques provide tangible solutions for current challenges in battery management across various industries. By optimizing SOC, the present invention improves battery performance and life. Accordingly, this information clearly establishes the industrial applicability of the techniques outlined in this application.

[0043] The use of the singular herein will not exclude the use of plural of the same, unless specifically stated otherwise. The use of the term "a" and "an" and "the" and "at least one" or the term "one or more" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be interpreted to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The use of the term "at least one" followed by a list of one or more items (for example, "at least one of A and B" or one or more of A and B) is to be interpreted to mean that one item from the list (A or B) or any combination of two or more items (A and B; A, A, and B; A, B, and B) of the list of items can be used, unless otherwise indicated herein or specifically contradicted by context. Similarly, as used herein, the word "or" is meant to mean any possible arrangement of items on the list. For example, a phrase, such as "A or B" or "A and B" means at least one of A or B or any combination thereof, such as A; B; both A and B; A and B; A, A, and B; A, B, and B; or any permutation of these.

[0044] The above detailed description is intended to be illustrative, not limiting. The scope of the disclosure should be determined, therefore, not with reference to the above description, but instead with reference to the appended claims, along with their full scope of equivalents.

Claims

1. An electrical system (112) for supplying power to at least one traction component and at least one accessory component (114) of an electric motor (100), said electrical system (112) comprising: A battery system (200) configured to supply power to components of the electric motor (100), the battery system (200) comprising: Multiple battery strings (244), wherein each battery string (202C, 202B, 202A) includes a battery module having at least one battery cell (206); An electronic control module configured to receive a representation of the state of charge of each battery string (202C, 202B, 202A), the electronic control module including control units (248, 240, 234), the control units being configured to: Determine which battery string (202C, 202B, 202A) has the highest state of charge; and When the highest state of charge exceeds the state of charge of another battery string (202C, 202B, 202A) reaching a threshold, based on the load demand of the at least one accessory component (114), the battery string (202C, 202B, 202A) with the highest state of charge is selected to provide power to the at least one accessory component (114); and Output (236), which is connected to the battery system (200) and configured to supply power to the at least one accessory component (114) but not to the at least one traction component.

2. The electrical system (112) according to claim 1, wherein the control unit (248, 240, 234) is a first control unit (248, 240, 234), wherein the electronic control module is a first electronic control module connected to the battery system (200) and includes the first control unit (248, 240, 234), and wherein the battery system (200) includes the first electronic control module.

3. The electrical system (112) according to claim 1, wherein the control unit (248, 240, 234) is a second control unit (248, 240, 234), wherein the electronic control module is a second electronic control module connected to the electric motor (100) and includes the second control unit (248, 240, 234), and wherein the second electronic control module is in electrical communication with a first electronic control module connected to the battery system (200).

4. The electrical system (112) according to claim 3, wherein the plurality of battery strings (244) is a first plurality of battery strings (244), and the electrical system (112) further comprises: The second plurality of battery strings (244), wherein each battery string (202C, 202B, 202A) in the second plurality of battery strings (244) includes a battery module having at least one battery cell (206); as well as A third electronic control module is configured to receive a representation of the state of charge (SOC) of each of the second plurality of battery strings (244) (202C, 202B, 202A). The second electronic control module communicates electrically with the third electronic control module.

5. The electrical system (112) according to claim 1, wherein the control unit (248, 240, 234) is configured to: Determine the load requirements of the at least one accessory component (114).

6. The electrical system (112) according to claim 1, wherein the control unit (248, 240, 234) configured to select the battery string (202C, 202B, 202A) with the highest state of charge to provide power to the at least one accessory component (114) based on the load demand of the at least one accessory component (114) when the highest state of charge exceeds the state of charge of another battery string (202C, 202B, 202A) reaching the threshold is configured to: Generate and output (236) command signals to close the contactors corresponding to the battery strings (202C, 202B, 202A) having the highest state of charge.

7. The electrical system (112) according to claim 1, wherein the control unit (248, 240, 234) is configured to select all battery strings in the battery string when the highest state of charge does not exceed the state of charge of another battery string (202C, 202B, 202A) reaching the threshold.

8. The electrical system (112) according to claim 1, wherein the threshold is a first threshold, and wherein the control unit (248, 240, 234) is further configured to: The state of charge of the corresponding battery string is compared with a second threshold; and When one of the states of charge is below the second threshold, the corresponding battery strings (202C, 202B, 202A) are selectively isolated to prevent the battery strings (202C, 202B, 202A) from supplying power to the at least one accessory component (114).

9. A method (400) for supplying power to at least one traction component and at least one accessory component (114) of an electric machine (100), the method (400) comprising: Receives a representation of the state of charge of each of the multiple battery strings (202C, 202B, 202A); Determine which battery string (202C, 202B, 202A) has the highest state of charge; and When the highest state of charge exceeds the state of charge of another battery string (202C, 202B, 202A) to a threshold, the battery string (202C, 202B, 202A) with the highest state of charge is selected to provide power to the at least one accessory component (114) based on the load demand of the at least one accessory component (114).

10. The method (400) of claim 9, wherein the threshold is a first threshold, and the method (400) further comprises: The state of charge of the corresponding battery string is compared with the second threshold. as well as When one of the states of charge is below the second threshold, the corresponding battery strings (202C, 202B, 202A) are selectively isolated to prevent the battery strings (202C, 202B, 202A) from supplying power to the at least one accessory component (114).

11. The method (400) according to claim 9, comprising: When the highest state of charge does not exceed the threshold of the state of charge of another battery string (202C, 202B, 202A), all battery strings in the battery string are selected.

12. The method (400) according to claim 9, wherein when the highest state of charge exceeds the state of charge of another battery string (202C, 202B, 202A) reaching the threshold, selecting the battery string (202C, 202B, 202A) having the highest state of charge to provide power to the at least one accessory component (114) based on the load demand of the at least one accessory component (114) comprises: Generate and output command signals to close the contactors corresponding to the battery strings (202C, 202B, 202A) having the highest state of charge.

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