The present disclosure generally relates to a system and a method for module level diagnostics and performance prognostics of a multi-cell electrical energy storage system.
An electrical energy storage or battery system or array may include a plurality of battery cells in relatively close proximity to one another. A plurality of battery cells may be assembled into a battery stack or module, and a plurality of battery modules may be assembled into a battery pack. Batteries may be broadly classified into primary and secondary batteries. Primary batteries, also referred to as disposable batteries, are intended to be used until depleted, after which they are simply replaced with new batteries. Secondary batteries, more commonly referred to as rechargeable batteries, employ specific high-energy chemistries permitting such batteries to be repeatedly recharged and reused, therefore offering economic, environmental and ease-of-use benefits compared to disposable batteries.
Rechargeable batteries may be used to power such diverse items as toys, consumer electronics, and rotary electric machines, such as electric motors-generators, such as for powering motor vehicles. Depending on the particular configuration of the rotary subject electric machine, the battery cells may be recharged via an offboard charging station and/or via onboard regeneration. Battery cells may be depleted of charge during operation of the powered item or through self-discharge during storage. Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without a connection between the electrodes or with an external circuit. Self-discharge decreases shelf life of batteries and causes them to initially have less than a full charge when actually put to use.
How fast self-discharge occurs in batteries is dependent on the battery type, it state of charge, ambient temperature, and other factors. Self-discharge is a chemical reaction, just as closed-circuit discharge is, and tends to occur more quickly at higher temperatures. Storing batteries at lower temperatures thus reduces the rate of self-discharge and preserves the initial energy stored in the battery. Self-discharge may also be affected by formation of a “passivation layer” on the battery electrodes over time, such as due to electrode material oxidation in the air.
A battery system includes a multi-cell rechargeable energy storage system (RESS) having a plurality of battery cell groups arranged in individual battery modules. The battery system also includes a battery controller network configured to monitor each of the battery modules. The battery controller network includes a plurality of cell monitoring units (CMUs), each respective one of the CMUs being electrically connected to a respective one of the battery modules and configured to process cell data for the respective battery module. The battery controller network also includes a plurality of voltage sensors mounted to or positioned on each CMU, each voltage sensor being configured to detect voltage across one respective cell group. The battery controller network additionally includes a plurality of microchips, each microchip being arranged on a respective one of the CMUs in communication with the respective voltage sensors.
Each microchip is programmed with a microchip algorithm inventory mode that, when executed by the respective microchip, is configured to interrogate the respective voltage sensor and retrieve data indicative of the detected voltages for the associated cell groups at predetermined time intervals over a predetermined timeframe. The microchip algorithm inventory mode is also configured to store the retrieved voltage data on the respective microchip. The microchip algorithm inventory mode is additionally configured to determine a discharge rate of each associated cell group using the stored voltage data. The microchip algorithm inventory mode is further configured to determine degradation of each associated cell group using the determined respective discharge rate.
The determination of degradation of the associated cell groups may be accomplished via comparison between the determined discharge rates of the associated cell groups.
The determination of degradation of the associated cell groups may be accomplished via comparison of the determined discharge rates of the associated cell groups with a threshold discharge rate.
The battery controller network may additionally include a plurality of temperature sensors. At least one of the plurality of temperature sensors may be mounted to or positioned on each of the CMUs and configured to detect temperatures of the associated cell groups. In such an embodiment, the microchip algorithm inventory mode may be additionally configured to interrogate the respective at least one of the plurality of temperature sensors and retrieve data indicative of the detected temperatures at predetermined time intervals over a predetermined timeframe. The microchip algorithm inventory mode may be also configured to store the retrieved temperature data on the respective microchip. The microchip algorithm inventory mode may be further configured to determine degradation of the associated cell groups using the stored temperature data.
The cell data for each respective cell group may include the retrieved voltage data and the retrieved temperature data. The microchip algorithm inventory mode may be additionally configured to predict degradation of each of the associated cell groups based on a trend in the respective cell data.
Multiple battery modules may be assembled into a battery pack. In such an embodiment, the battery controller network may additionally include a pack current sensor configured to detect an electrical current being supplied to the battery pack. The battery controller network may further include an electronic controller in communication with the plurality of CMUs and with the pack current sensor, and programmed with a battery pack artificial intelligence (AI) algorithm. The battery pack AI algorithm, when executed by the electronic controller, may be configured to predict degradation of each of the associated modules in the battery pack using the cell data and the battery pack current.
The battery controller network may additionally include an IT cloud server arranged remotely from the RESS and in wireless communication with the plurality of microchips. The IT cloud server may be configured to receive the cell data from the respective microchips and store the received cell data in an IT cloud database.
The IT cloud server may be programmed with an IT cloud artificial intelligence (AI) algorithm configured to select and match up cell groups using the respective cell data. Specifically, the inventory mode may be applied to standalone battery modules, such as during long-term storage at a service warehouse. Cell data collected during long-term storage may be used in vehicle service to match battery modules with similar cell discharge rates and other characteristics.
The inventory mode may be configured to interrogate the respective voltage sensors and retrieve data indicative of the detected voltage at predetermined time intervals over the predetermined timeframe when the associated cell groups are not being depleted of charge through a load or resides in a stored state.
The inventory mode may be configured to determine degradation of the associated cell groups using a predefined voltage threshold programmed into the microchip algorithm.
A method of monitoring and diagnosing, via a battery controller network, degradation of a multi-cell rechargeable energy storage system (RESS) having a plurality of battery cell groups arranged in individual battery modules, as described above, is also disclosed.
The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of the embodiment(s) and best mode(s) for carrying out the described disclosure when taken in connection with the accompanying drawings and appended claims.
Referring to
The vehicle 10 additionally includes a programmable electronic controller 22 and a multi-cell rechargeable energy storage system (RESS) 24. A general structure of the RESS 24 is schematically shown in
The RESS 24 is configured to generate and store electrical energy through heat-producing electro-chemical reactions for supplying the electrical energy to the power-sources 14 and 20. The electronic controller 22 may be programmed to control the powertrain 12 and the RESS 24 to generate a predetermined amount of power-source torque T, and various other vehicle systems. The electronic controller 22 may include a central processing unit (CPU) that regulates various functions on the vehicle 10, or be configured as a powertrain control module (PCM) configured to control the powertrain 12. In either of the above configurations, the electronic controller 22 includes a processor and tangible, non-transitory memory, which includes instructions for operation of the powertrain 12 and the battery system 24 programmed therein. The memory may be an appropriate recordable medium that participates in providing computer-readable data or process instructions. Such a recordable medium may take many forms, including but not limited to non-volatile media and volatile media.
Non-volatile media for the electronic controller 22 may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random access memory (DRAM), which may constitute a main memory. Such instructions may be transmitted by one or more transmission medium, including coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to a processor of a computer, or via a wireless connection. Memory of the electronic controller 22 may also include a flexible disk, hard disk, magnetic tape, another magnetic medium, a CD-ROM, DVD, another optical medium, etc. The electronic controller 22 may be configured or equipped with other required computer hardware, such as a high-speed clock, requisite Analog-to-Digital (A/D) and/or Digital-to-Analog (D/A) circuitry, input/output circuitry and devices (I/O), as well as appropriate signal conditioning and/or buffer circuitry. Algorithms required by the electronic controller 22 or accessible thereby may be stored in the memory and automatically executed to provide the required functionality of the powertrain 12 and the RESS 24.
The RESS 24 may also be part of a battery system 34 that includes a battery controller network 36. The battery controller network 36 is generally configured to monitor operation of the RESS 24, and specifically each of the battery modules 30. As shown in
With continued reference to
The inventory mode 44A of each microchip 42 is specifically configured to retrieve data 46 indicative of the detected voltages for the associated cell groups 28 at predetermined time intervals t over a predetermined timeframe T. The inventory mode 44A of each microchip 42 is also configured to store the retrieved voltage data 46 on the respective microchip 42. The inventory mode 44A on each microchip 42 is additionally configured to determine a discharge rate DR of each associated cell group 28 using the voltage data 46 retrieved at predetermined time intervals t over the predetermined timeframe T The inventory mode 44A on each microchip 42 is further configured to determine or diagnose degradation 48 of each associated cell group 28 using the determined discharge rate DR of the respective cell groups. The inventory mode 44A may also be programmed to generate a sensory signal or alert 50, such as via setting a digital code or an audio-visual flag in the vehicle 10, indicative of the degradation 48 or a threshold discharge rate 52 having been reached by a particular cell group 28. Such an alert 50 may be retrieved by an authorized technician or communicated to a central authority including a database, such as an IT cloud server, which will be described in greater detail below.
The determination of degradation 48 of the associated cell groups 28 may be accomplished via comparison between the determined discharge rates DR of the associated cell groups 28. Alternatively, the determination of degradation 48 of the associated cell groups 28 may be accomplished via comparison of the determined discharge rates DR of the associated cell groups 28 with the threshold discharge rate 52. The battery controller network 36 additionally includes a plurality of temperature sensors, e.g., thermistors, 54. At least one of the plurality of temperature sensors 54 may be mounted to or positioned on each of the CMUs 38 to detect temperatures of the associated cell groups 28. As shown in
The microchip 44 algorithm inventory mode 44A may be additionally configured to interrogate the respective temperature sensors 54 and retrieve data 56 indicative of the detected temperatures at predetermined time intervals t over a predetermined timeframe T The algorithm inventory mode 44A may be also configured to store the retrieved temperature data 56 on the respective microchip 44. The algorithm inventory mode 44A may be further configured to determine degradation of the associated cell groups 28 using the stored temperature data 56. The inventory mode 44A may be configured to interrogate individual voltage sensors 40 and retrieve the data 46 indicative of the detected voltages at predetermined time intervals t over a predetermined timeframe T when the associated cell groups 28 of the RESS 24 are ether not being depleted of charge through a load or reside in a stored state. Alternatively, the inventory mode 44A may be configured to determine degradation of the associated cell groups 28 using a predefined voltage threshold 46A programmed into the microchip algorithm 44A.
In general, the temperature data 56 may be indicative of a runaway event affecting individual cell groups 28. The term “thermal runaway event” refers to an uncontrolled increase in temperature in a battery system. During a thermal runaway event, the generation of heat within a battery system or a battery cell exceeds the dissipation of heat, thus leading to a further increase in temperature. Generally, a thermal runaway event may be triggered by various conditions, including a short circuit within the cell, improper cell use, physical abuse, manufacturing defects, or exposure of the cell to extreme external temperatures.
The cell data for each respective cell group 28 may include the retrieved voltage data 46 and the retrieved temperature data 56. The microchip 44 algorithm inventory mode 44A may be additionally configured to determine a trend 58 in the respective cell data, for example via separate trend determinations for voltage and temperature data 46, 48, and predict degradation of each of the associated cell groups 28 based on the trend 58. When employed on the vehicle 10, multiple cell modules 30 may be assembled into a battery pack 60 (shown in
On the vehicle 10, the battery controller network 36 may include the vehicle electronic controller 22 in communication with the plurality of CMUs 38 and the pack current sensors 62, 64, such as via low-voltage lines and an isolated communications pathway. The vehicle electronic controller 22 may be programmed with a battery pack artificial intelligence (AI) algorithm 66 that, when executed by the electronic controller, is configured to predict degradation of each of the associated modules 30 in the battery pack 60 using the cell data and battery pack electrical current I. Specifically, the AI algorithm 66 may be configured to assess incoming data from the respective voltage sensors 40, temperature sensors 54, pack current sensor(s) 62, and pack voltage sensor(s) 64.
With resumed reference to
Generally, modules employing cell groups having comparable levels of degradation perform more effectively. The AI algorithm 74 may be specifically configured to assess incoming data from the respective voltage sensors 40, temperature sensors 54, pack current sensor(s) 62, and pack voltage sensor(s) 64 to evaluate individual modules from multiple vehicles. Requisite communication between the respective microchips 44 of individual vehicles and the IT cloud server 70 may be cellular or via wireless local area networking (Wi-Fi) facilitated by a cloud edge residing on a cellular base station (not shown) for reduced latency, or via an earth-orbiting satellite 76 (shown in
With reference to
A method 100 of monitoring and diagnosing degradation of cell groups 28 is shown in
Executing the microchip algorithm inventory mode 44A, in frame 104A, specifically includes interrogating the respective voltage sensors 40 and retrieving data 46 indicative of the detected voltage for the associated cell groups 28 at predetermined time intervals t over the predetermined timeframe T From frame 104A, the method moves on to frame 104B, where executing the microchip algorithm inventory mode 44A includes storing the retrieved voltage data 46 on the respective microchip 44. After frame 104B the method proceeds to frame 104C, where executing the microchip algorithm inventory mode 44A includes determining the discharge rate DR of each associated cell group 28 using the stored data 46.
In frame 104C, the inventory mode 44A may be configured to interrogate individual voltage sensors 40 and retrieve the data 46 indicative of the detected voltages at predetermined time intervals t over a predetermined timeframe T when the associated cell groups 28 in the RESS 24 are ether not being depleted of charge through a load or reside in a stored state. Alternatively, the inventory mode 44A may be configured to determine degradation of the associated cell groups 28 using the predefined voltage threshold 46A programmed into the microchip algorithm 44A, as described with respect to
In frame 104F, the method may include interrogating the respective temperature sensor(s) 54 and retrieve data 56 indicative of the detected temperatures at predetermined time intervals t over the predetermined timeframe T. From frame 104F, the method may move on to frame 104G, where the method includes storing the retrieved temperature data 56 on the respective microchip 44. After frame 104G, the method may move on to frame 104H, where the method includes determining degradation of the associated cell groups 28 using the stored temperature data 56. Following either of the frames 104D or frame 104H, the method may proceed to frame 106. In frame 106, the method includes predicting, via the microchip algorithm inventory mode 44A, degradation of each of the associated cell groups 28 based on the assessed trend 58 in the respective cell data.
Following either of the frames 104D, 104H, or 106, the method may proceed to frame 108. In frame 108, the method includes detecting, on the vehicle 10 via the pack current sensor 62, the electrical current I being supplied to the battery pack 60. After frame 108, the method may move on to frame 110. In frame 110 where the method additionally includes predicting, via the battery pack AI algorithm 66 executed by the vehicle electronic controller 22, degradation of each of the associated modules 30 in the battery pack using the cell data and the battery pack current I. From frame 104D, 104H, 106, 108, or 110, the method may move on to frame 112, where the method includes receiving the cell data from the respective microchips 44 and storing the received cell data in the IT cloud database 72 via the IT cloud server 70 in wireless communication with the plurality of microchips 44.
After frame 112, the method may move on to frame 114. In frame 114 where the method includes selecting and matching up cell groups 28 using the respective cell data via the IT cloud AI algorithm 74 programmed into the IT cloud server 70, for example as described with respect to
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment may be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.