Communication system for monitoring electric battery systems

Abstract

This disclosure relates to a communication system for monitoring an electric battery system. The communication system is a multi-layer system having separate time-division multiple access (TDMA) for each level.

Description

Background Art

[0001] Battery systems comprising multiple battery cells are used in a wide range of modern power applications. For example, they are used to supply power to electric vehicles and they are used in commercial applications such as industrial power applications, transportation, and power supply for modern electronic devices. Given the relatively high power requirements of such applications, battery systems often comprise multiple battery cells that are coupled together to achieve the required power output. The battery cells can be coupled together to form battery packs, and the battery system can comprise one or more battery packs.

[0002] It is common to connect the battery system to a battery management system (BMS) configured to ensure that the battery system operates within its safe operating area. The safe operating area is defined as the voltage, current, and environmental conditions under which the battery system is expected to operate without self-damage. For further details, the interested reader is referred to the following Wikipedia website, https: / / en.wikipedia.org / wiki / Battery_management_system.

[0003] In certain known applications, the performance characteristics of the battery cells within the battery system can be monitored to identify potential fault operations of the battery cells before a catastrophic failure occurs. Such measurements are performed using a device called a cell monitoring device (CMD). The CMD provides cell-level measurements such that separate measurements are made for each individual cell and the information obtained is related to the individual cell. Further measurements can be obtained using auxiliary devices that obtain measurements from groupings of cells or at the battery pack level. The measurements made by the CMD and / or the auxiliary devices are typically transmitted through the battery management system towards a central controller.

Summary of the Invention

[0004] For proper maintenance and adjustment of electric battery systems, measurements must be acquired with high accuracy. However, as electric battery systems scale to larger sizes, latency issues can arise for measurements and / or communications traveling greater distances throughout the battery management system. Therefore, a system for improved communication within the battery management system is needed. Exemplary embodiments presented herein employ a multilevel communication system employing a time-division multiple access (TDMA) protocol.

[0005] An exemplary embodiment presented herein comprises a communication system for monitoring an electric battery system. The communication system includes a single time-division multiple access (TDMA) protocol operating across the communication system. The communication system further comprises a plurality of electronic devices located at a first level of the communication system, each electronic device configured to acquire measurements on at least one respective battery cell of the electric battery system, and the plurality of electronic devices are arranged in at least two subgroups of the electronic device. It should be understood that the electronic devices may be in the form of a CMD, an auxiliary device, or any other component capable of performing cell or battery-related measurements or controlling cell or battery-related functions. It should be further understood that the term “at least one respective battery cell” includes individual battery cells, multiple battery cells in a battery pack.

[0006] The communication system further comprises at least two wireless manager units located at a second level of the communication system, and each subgroup of electronic devices communicates with its respective wireless manager unit via a first TDMA schedule and a first communication medium. The communication system further comprises at least one wireless director unit located at a third level of the communication system, and each wireless manager unit and at least one wireless director unit communicates via a second TDMA schedule and a second communication medium.

[0007] At least one radio director unit is configured to determine a second TDMA schedule, and each radio manager unit is configured to determine its own first TDMA schedule, and the first and each second TDMA schedule define the timing for reporting and command messaging based on measurements across the entire communication system in a synchronized manner.

[0008] An exemplary embodiment is also directed to a method in a communication system for monitoring an electric battery system, the communication system operating over a single time-division multiple access (TDMA) protocol. The method includes determining a first TDMA schedule for communication between a plurality of electronic devices and at least two wireless manager units over a first communication medium, the plurality of electronic devices being located at a first level of the communication system and arranged in at least two subgroups of electronic devices; and the at least two wireless manager units being located at a second level of the communication medium.

[0009] The method further includes determining a second TDMA schedule for communication between at least two radio manager units and at least one radio director unit via a second communication medium, the at least one radio director unit located at a third level of the communication system. The method also includes acquiring measurements on each of at least one battery cell of an electric battery system via a plurality of electronic devices. The method further includes transmitting the acquired measurements to each of at least two radio manager units via a first TDMA schedule and via a first communication medium. The method also further includes transmitting the acquired measurements to at least one radio director unit via a second TDMA schedule and via a second communication medium. The at least one radio director unit is configured to determine a second TDMA schedule, and each radio manager unit is configured to determine its respective first TDMA schedule, the first and each second TDMA schedules define timing for reporting and command messaging based on measurements across the entire communication system in a synchronized manner.

[0010] An exemplary embodiment is also directed toward a computer-readable medium that stores instructions causing a communication system to perform the method described herein, when executed by a processor of a communication system for an electronic battery system.

[0011] The foregoing will be further illustrated with the following more detailed description of exemplary embodiments, as illustrated in the attached drawings, which use different reference letters to refer to the same part throughout the figures. The drawings are not necessarily to scale, and instead are intended to illustrate exemplary embodiments. [Brief explanation of the drawing]

[0012] [Figure 1] This is an illustrative diagram of the measurement, monitoring, and control of components within a battery monitoring system. [Figure 2]This is an illustrative example of a communication system within a battery monitoring system. [Figure 3A] This is an illustrative example of a communication system within a battery monitoring system. [Figure 3B] This is an illustrative example of a communication system within a battery monitoring system. [Figure 4] This is an illustrative example of a communication system within a battery monitoring system. [Figure 5] This is an illustrative diagram of a communication system within a battery monitoring system, according to some of the exemplary embodiments presented herein. [Figure 6] Some of the exemplary embodiments presented herein illustrate an example of a switching mechanism associated with a wireless manager unit. [Figure 7] Figure 5 shows an illustrative example of a messaging sequence diagram of a communication system, based on some of the exemplary embodiments presented herein. [Figure 8] Figure 5 shows an illustrative example of a messaging sequence diagram of a communication system, based on some of the exemplary embodiments presented herein. [Figure 9] Some of the exemplary embodiments presented herein illustrate a multilayer communication system within a battery monitoring system. [Modes for carrying out the invention]

[0013] Herein, exemplary embodiments illustrated in the accompanying drawings are referenced in detail. The following description refers to the accompanying drawings, and unless otherwise noted, elements numbered the same in different drawings represent identical or similar elements. The implementations shown in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with aspects related to the present invention as described in the accompanying claims.

[0014] Means for providing a communication system to a battery monitoring system are described herein. The battery monitoring system may be provided within an electric vehicle and / or electric battery storage means. An overview of the battery monitoring system is provided as context. A battery system typically comprises a number of cells wired in a configuration that provides the desired battery system voltage and capacity, and additional components necessary for the safe operation of the cells and the transfer of energy to and from the cells. A cell is the basic unit of any battery system. The defining characteristic of a cell is its electrochemical properties. For the chemical properties of a particular cell, there are minimum, standard, and maximum voltages determined by the electrochemical properties of the cell, not by the system configuration. Voltage cannot be changed except by changing the electrochemical state of the cell. Cells may be wired in parallel to increase the overall capacity, but these parallel cells can simply be considered as a larger single cell from the standpoint of cell monitoring, as they still have the same voltage characteristics as determined by their electrochemical properties.

[0015] Cells can also be wired in series. A series stack of cells has a voltage that is primarily determined by the stack configuration. The stack voltage is the sum of the cell voltages. The stack voltage can be changed by adding or removing cells without changing their electrochemical state. Typically, a stack of cells is charged and discharged, and their electrochemical state changes in conjunction. Each cell must be monitored to ensure it remains within the safe operating area. This is the job of a cell monitoring device (CMD). The CMD provides cell-level measurements so that separate measurements are taken for each individual cell and the information obtained is relating to that individual cell.

[0016] A battery pack consists of multiple cells connected in series. A battery pack provides the entire battery system voltage. Multiple battery packs can be wired in parallel, but not in series, to increase the capacity of the battery system. Cells can be grouped into modules. The defining characteristics of a module are its physical configuration, such as the number and connectivity between several cells. A module can consist of any number of cells. A module can consist of two or more cells, or an entire pack. If only a single pack exists within a battery system, a module can encompass the entire battery system.

[0017] However, more often, a pack consists of multiple modules, each module comprising multiple cells in series. These modules are then wired in series, parallel, or a combination of series and parallel. Modules wired in parallel, each carrying a battery system voltage, can be considered a pack. Modules have a defined size and shape and are typically packaged in some kind of enclosure.

[0018] The module configuration is determined by the physical requirements of the battery pack. Often, modules are configured to have a voltage low enough to be handled without the risk of electric shock. Often, modules are configured for a number of cells that matches the number of voltage sensing inputs on the cell monitoring device. A very common example is a 12-cell monitoring device. In that case, the module consists of 12 cells and connections to the cell monitoring device. In many battery packs, the properties of the CMD define the module configuration, and the battery pack is then constructed from multiple such modules.

[0019] The CMD can be used to obtain cell-level measurements of the battery system, while an auxiliary device can be used to obtain measurements associated with the number of modules, packs, and / or cells of the electric battery system. The auxiliary device can provide module-level, pack-level, and / or system measurements and can be flexibly arranged anywhere within the electric battery system. The term "electronic device" is used herein as a device that provides measurements within an electric battery monitoring system. It should be understood that the electronic device can be the CMD, the auxiliary device, or any other device located within the battery system that is capable of obtaining measurements or providing control.

[0020] FIG. 1 illustrates an exemplary electric battery system featuring an auxiliary device 115 as well as various CMDs 107. The electric battery system 116 of FIG. 1 comprises a single battery pack 117 featuring eight battery modules 101. Each battery module 101 features twelve battery cells 105. Each battery cell 105 is monitored by a respective CMD 107 that provides cell-level measurements. Each CMD 107 is configured to communicate with a central controller or BMS via a short-range wireless communication bus 109. To enable such communication, each CMD includes a respective short-range wireless antenna 111. While the example of FIG. 1 illustrates short-range wireless communication, it should be understood that other forms of communication systems can be used. For example, the electric battery system of FIG. 1 can feature communication channels in the form of optical and electrical buses such as long-range wireless, Controller Area Network (CAN), Ethernet, Isolated Serial Peripheral Interface (isoSPI), Local Interconnect Network (LIN), Flexray, etc.

[0021] According to some exemplary embodiments, auxiliary devices may be located on or within an electric battery system to obtain module-level or pack-level measurements. In the example provided in Figure 1, auxiliary device A is located within the housing of each battery module 101. Such arrangement allows the auxiliary device to obtain module-level measurements of the battery system. It should be understood that auxiliary devices may be located near multiple modules so that a single auxiliary device can obtain module-level measurements on multiple modules. In such exemplary embodiments, the auxiliary device may be located, for example, between two adjacent modules.

[0022] In the example provided by Figure 1, auxiliary device A is also provided in a location that enables the acquisition of pack-level measurements. Specifically, auxiliary devices A120, 121, and 122 provide examples of auxiliary devices featuring a pack voltage measuring sensor, a battery system insulation resistance measuring sensor, and a pack current measuring sensor, respectively. A further example of the placement of auxiliary devices for acquiring pack-level measurements is provided in 123, where the auxiliary device is placed in close proximity to a pack switch, commonly called a contactor, as well as associated drive and sensing circuits. Auxiliary device A124 may be configured to measure the output voltage of the battery pack. In a further example, auxiliary device A may be placed in close proximity to the main power connection to the battery system (traction connector) 125. The power connection includes a safety interlock switch indicating the presence or absence of a mating connector. Auxiliary device A on 125 can report the state of this safety interlock switch.

[0023] The enlarged view 115 of the auxiliary device A provides an example of a feature that may be included in the device. In the example provided in FIG. 1, the auxiliary device A may include a temperature sensor and a voltage sensor. It should be understood that the auxiliary device may include any number or type of sensors used when monitoring an electric battery system. Examples of such sensors may be temperature, voltage, current, pressure, shock, gas, leakage, security / tamper detection, interlock status, fluid flow rate, gas flow rate, actuator position, fan / motor speed detector, and / or other environmental sensors. The auxiliary device 115 may further include a radio frequency antenna 113 used to communicate with the central controller 118, or the BMS, via the short-range wireless communication bus 109 in the same manner and using the same protocol as the individual CMDs.

[0024] A battery monitoring system, such as the system illustrated in FIG. 1, requires that the communication system transmit messages and commands to various components of the monitoring system. The battery cell monitoring system has various requirements. For example, the monitoring system should be able to measure each cell voltage and optionally temperature with high precision. Further, the measurements should ideally be made simultaneously for all cells to facilitate comparison of performance between cells. The measurements should also be made with great care to ensure that the data connection between cells is reliable and voltage insulation is maintained. In addition, the system should be easy to manufacture and service. The system should also be scalable, and in the case of a large-scale electric battery system, the latency issue should be minimized.

[0025] Figure 2 is an illustrative example of a communication system 200 associated with a battery monitoring system known in the art. Figure 2 depicts a host 201 representing an application where the battery system is used, for example, in a vehicle or static energy storage. The host 201 commands a controller or battery management system (BMS) master 203. The controller 203 interacts with a set of electronic devices (ED1-EDx) that perform measurements on any number or grouping of lithium-ion cells in a pack. The electronic devices may also provide control elements such as relays or contactors, or electronically triggered fuses, or thermal control. The electronic devices may be CMDs, auxiliary devices, or any other nodes in the battery monitoring system that can perform measurements on one or more cells, modules, or battery packs. A typical electronic device measures 12 cells, and multiple electronic devices measure all cells in a pack, e.g., 96 or 192 cells. Thus, there may be 8 or 16 electronic devices in the system. Electronic devices are arranged in a daisy-chain, commands from the controller 203 to the electronic devices are passed down the daisy-chain, and measured data is returned from the electronic devices up the daisy-chain. The daisy-chain is typically implemented using a protocol such as Isolated Serial Peripheral Interface (isoSPI).

[0026] System 200 has several drawbacks. The latency, which is the time it takes for a message to travel from the controller to or from the electronic device, varies from one electronic device to another. Therefore, it becomes difficult to synchronize all electronic devices so that they perform measurements precisely at the same time.

[0027] Figure 3a illustrates a communication system 300a employing an alternative approach. Here, daisy-chain communication is replaced by radio frequency channels, e.g., 433 MHz, 868 MHz, 915 MHz, 2.4 GHz, or 5.7 GHz in the Short-Range Device (SRD) or Industrial Scientific and Medical (ISM) bands. The channels consist of antennas on the controller (now called the Radio Manager or RM303a) and each of the electronic devices (ED1-ED1x), enabling communication between the electronic devices and the host 301a. This is sometimes known as a radio BMS because the communication is over a long-range radio link.

[0028] Communication system 300a has many advantages over the daisy-chain approach illustrated in Figure 2. For example, communication latency is constant between any pair of antennas (i.e., single hop). Furthermore, the number of cables and connectors is reduced. However, maintaining single-hop communication within the range of a battery pack is extremely difficult. Often, a cell cannot directly "see" the RM, and instead, messages must be relayed through intermediate cells. This is a mesh network solution. These are also undesirable because they increase and make latency unpredictable. In addition, synchronizing the measurement times of all electronic devices remains a problem.

[0029] Figure 3b shows a modified wireless BMS, where the long-range wireless approach is replaced by a short-range wireless multidrop approach. Each electronic device is weakly coupled to the bus antenna, resulting in low and predictable latency. Furthermore, latency is the same for all RM / electrical device pairs using such an approach. Signals are conducted along the bus antenna, thus eliminating the need for multihop or mesh networks.

[0030] The bus antenna in Figure 3b is typically a pair of wires configured as a transmission line. Bus antennas can be several meters long. A typical automotive pack might require a bus antenna 5 meters long. However, some applications require much longer bus antennas, such as 20 meters or more. The longer the bus antenna, the greater the signal power loss along it.

[0031] Due to bus antenna losses, there is a length over which electronic devices located at the ends of the bus antenna may not receive sufficient power. For example, a transmitter in the RM may output -20 dBm. To minimize the load on electrical devices on the bus antenna, there may be a 30 dB attenuation across the short-range gap. Other losses in the system may add up to 10 dB. Thus, the total loss of the system may be (-20 - 30 - 10) = -60 dBm. An electronic device receiver may have a sensitivity of -80 dBm minimum received signal strength. This leaves room for up to 20 dB of additional loss. The bus antenna may have a loss of 2 dB per meter. Thus, the maximum bus antenna length in this example is 20 dB / 2 dB = 10 meters.

[0032] Figure 4 illustrates a communication system 400 in the form of a modified version of Figure 3b, where the total length of the bus antenna can be greater than shown by the simple calculation above. The splitter 405a / combiner 405b component splits the RF signal from the controller 403 between two bus antennas. The power of each bus antenna is reduced by 3 dB (divided by 2). However, the bus antenna only needs to be half the length, as long as it only needs to cover half of the cell. The second bus antenna sees the same power as the first bus antenna.

[0033] The splitter 405a / combiner 405b does not need to be located in the controller, and in large systems, the controller 403 and splitter 405a / combiner 405b may be located at a certain distance from the electronic devices. The electronic devices may be grouped into modules or racks, and the entire system may be the same size as or larger than a shipping container. The host 401 may also be located at a certain distance.

[0034] Of course, a possible solution would be to have multiple electronic devices, all communicating with the host. However, this reintroduces the previous problem related to measurement synchronization. To properly maintain a battery monitoring system, it is useful for all electronic devices to perform their measurements simultaneously, for example, within a few microseconds.

[0035] Accordingly, exemplary embodiments are presented herein, providing a communication system for use with electronic battery monitoring in which communication losses due to system size can be minimized. Furthermore, the communication system presented herein also provides fixed, low latency for communication, eliminating the need for hopping or identical latency hopping across all electronic devices. In addition, the exemplary embodiments presented herein provide synchronization of measurements across all electronic devices in the system within a microsecond timeframe. The exemplary embodiments presented herein further provide network formation at a single node (e.g., controller or wireless manager) for reliable and repeatable network formation time and fault identification. Maintaining isolation between subsystems against high voltages (e.g., 500VDC to 1500VDC) is also provided, as is low power milliamperes (mA) per node with microampere (uA) sleep current.

[0036] Figure 5 illustrates an electric battery monitoring communication system according to an exemplary embodiment presented herein. The communication system 500 comprises a three-level architecture. The first level comprises various groupings of electronic devices. The example in Figure 5 illustrates three distinct groupings, each containing four electronic devices (ED1:1 to ED3:4). The second level comprises several radio manager (RM) units 505a to 505c. Each distinct radio manager unit is associated with each group of electronic devices. In the example shown in Figure 5, RM unit 505a is associated with the first grouping featuring electronic devices ED1:1 to ED1:4, RM unit 505b is associated with the second grouping featuring electronic devices ED2:1 to ED2:4, and RM unit 505c is associated with the third grouping featuring electronic devices ED3:1 to ED3:4. The wireless director unit 503 is located at the third level of the communication system and has direct communication with the host 501.

[0037] It should be noted that the communication systems in Figures 2 to 4 have a two-level architecture in which a controller or radio manager is positioned between the host and the electronic devices. Therefore, exemplary embodiments presented herein increase the number of levels from two to three or more. Multiple electronic devices are grouped into branches, and each branch is connected to one RM unit. Each group of electronic devices on the first level of the architecture is synchronized to its associated RM unit on the second level. Each RM unit on the second level of the architecture is then synchronized to the radio director 503 on the third level. The communication protocol is unified across all levels. RM units 505a to 505c can switch from communicating with a higher level to communicating with a lower level. Switching from one to the other occurs in a much shorter time than it takes to transmit a packet.

[0038] The highest level has at least one node, which is the Wireless Director (RD) unit 503. At the start of a frame in RD unit 503, it broadcasts to the second level, RM units 505a-505c. The second level is timed with respect to packets from the first level and follows the instructions contained in the RD unit broadcast. RM units 505a-505b broadcast to all their respective electronic devices on the third level.

[0039] In operation, all components in Figure 5 operate using the same communication protocol, for example, the Time Division Multiple Access (TDMA) protocol. However, different architectural layers of system 500 operate using separate TDMA timing schedules. It should be further understood that different architectural layers of system 500 may also include different communication media, for example, far-field radio, short-field radio, optical, electromagnetic, or any other form of communication media. RM units 505a-505c located in the central or second layer have the function of switching between the separate communication media of the different architectural layers. It should be understood that different layers do not need to include separate communication media, and the same medium may be used. In the example illustrated in Figure 5, the first level of the communication architecture includes a short-field radio communication medium, and the third layer of the communication architecture includes a far-field radio communication medium.

[0040] Figure 6 illustrates an example of a switching mechanism that may be included in each RM unit 505a-505c. RM units 505a-505c switch between two physical channels at a speed fast enough to maintain synchronization between EDs. If synchronization can be maintained for 200ms, a TDMA scheduling frame rate much smaller than 200ms is required to maintain synchronization. This may require a frame rate of 10ms to 100ms.

[0041] The properties of the physical channel can change. In embodiment a), the RD<->RM layer (communication architecture level 3) is a long-range wireless using a standard 2.4GHz antenna. The RM<->ED layer (communication architecture level 1) is a short-range wireless multidrop bus antenna approach.

[0042] Other communication protocols, such as Bluetooth® or IEEE 802.11, also include mechanisms for synchronizing the clocks of multiple nodes. However, these protocols cannot operate between two or more levels without buffering and loss of tight synchronization. There are also mesh networks, such as Bluetooth® Mesh or SmartMesh, which operate across multiple levels or hops. However, these are non-deterministic and have variable latency and uncertain synchronization because the number of hops that may be required for a message or synchronization to reach all nodes is not known in advance. Mesh networks use a single antenna or channel for all links. Mesh networks can maintain synchronization across layers, but such synchronization is difficult because the number of layers or hops is not deterministic. In particular, mesh networks can be synchronized at the high cost of communication and configuration overhead. Essentially, variable latency must be measured and compensated for. The synchronization achieved is difficult to predict (non-deterministic) and is generally worse than what can actually be achieved.

[0043] Furthermore, some wireless systems use multiple antennas to determine direction. These systems rapidly switch between antennas while maintaining carrier coherence (i.e., continuous phase of the carrier). Exemplary embodiments presented herein do not require coherence, and antenna switching occurs between packet transmissions, not during packet transmission. Each packet is independent and, depending on the state of the switch, is received or transmitted from a different transceiver.

[0044] The exemplary embodiments differ in that a single radio block is switched between two different physical channels. Embodiment a) is a good example where the RD<->RM layer is far-range radio and the RM<->ED layer is a short-range radio bus antenna. Embodiment b) shows far-range radio antennas for both layers, which may be desirable if the two antennas are located in different places, possibly on opposite sides of a metal screen. Embodiment c) shows a wired (coaxial or twisted-pair) RF connection from RM<->RD and a short-range radio bus antenna from RM<->ED. The physical nature of the radio link, whether wired, short-range, or far-range, is irrelevant. In any case, the modulated signal is transmitted and received by the same radio block on RM.

[0045] It should be understood that the use of RM units 505a-505c, which feature a switching mechanism, is merely an example. A single radio is not required in RM units 505a-505c; using two radio blocks instead without switching will also work. However, the circuit will be larger and more complex. Using two radio blocks in this way does not offer any additional benefits as they will not operate simultaneously, resulting in a waste of circuit resources.

[0046] According to an exemplary embodiment, the RD unit 503 is configured to determine the TDMA schedule for communication between the third and second levels of the system architecture, i.e., between the RD unit 503 and each RM unit 505a to 505c. Similarly, each RM unit 505a to 505c is configured to determine the TDMA schedule for each ED grouping. The TDMA schedule defines the timing for measurement sample time, measurement reporting, and command messaging through the communication system in a synchronous manner.

[0047] Figure 7 illustrates an exemplary TDMA timing schedule that may be used by the communication system 500 in Figure 5. The communication timing is divided into frames, each frame being a complete instruction / synchronization / response cycle. Each frame is divided into one or more slots. A frame consists of multiple steps. The function and order of the steps are not critical, and many arrangements will work. The arrangement in Figure 5 is provided simply as an example. It should be understood that there is an RD-to-RM phase that synchronizes all RM clocks and sets the timing for subsequent communications, as well as an RM-to-ED phase that synchronizes all ED clocks, communications, and measurements.

[0048] This synchronization process can occur in every frame, but less frequently if the nodes remain synchronized for longer periods. Synchronization must be performed frequently enough to ensure all nodes remain within the specified timing error limits. It should be understood that intermediate layers (e.g., RM on layer 2 in a 3-layer system) can communicate both to higher layers (RD on layer 3) and lower layers (ED on layer 1). It is advantageous that these communications operate using the same radio circuitry but through different media. In one exemplary embodiment, the RD, RM, and ED have a single radio block. In the RM, the radio input / output is switched between the two media.

[0049] In the example provided in Figure 7, the first slot is a broadcast from the highest level (level 3 in this example) RD unit 503 to all level 2 RM units 505a-505c. All RM units 505a-505c configure the antenna switch from level 3 to level 2, as shown in slot 1 “RM Switch RM to RD” in Figure 7. Specifically, in slot 1 of Figure 7, the RD (indicated as “RD LVL3”) sends a broadcast message, indicated by a solid black line, to all RMs in Figure 5 (indicated as “RM1 LVL2”, “RM2 LVL2”, and “RM3 LVL2”).

[0050] The first slot synchronizes the communication for the rest of the frame and instructs the RM unit on the response that the RD unit expects to see in subsequent slots. Not all ED and RM units need to respond in a single frame; communication can be extended to multiple frames if necessary.

[0051] In the example of slot 2 in Figure 7, all RM units 505a-505c switch their communication to the first architecture level (indicated as "RM switch 2 to 1 (RM to ED)") and send commands to their respective EDs. Each RM unit then broadcasts to all EDs connected on the same branch within its grouping. RM units 505a-505c command each ED to perform which measurements (voltage, temperature, etc.) and when. Multiple measurements may be commanded and performed at different times.

[0052] As instructed in the current example, all EDs perform measurements in slot 3 and collect the results. Specifically, in slot 3, the EDs perform measurements, and all measurements are synchronized to the reception of broadcast packet timing in slot 2, and then to the RD broadcast packets in slot 1. In slots 4, 5, and 6, the EDs return the measurement results to their respective RM units, one ED in each slot. It should be understood that all RM units can communicate in parallel, as they all switch to their respective channels. In slots 4, 5, and 6, each RM unit can operate at a different frequency to avoid interference between RM / ED channels. The RM units receive and store the results for transmission in later slots. In slots 7, 8, and 9, all RM units switch their antennas back to the channel to RD unit 503. Each RM unit 505a-505c transmits its stored results to the slot designated for it in the broadcast in slot 1. It should be further understood that the measurement and data returns are temporally separated. Measurement M occurs in frame F and is returned in frame F, or it can be stored or placed in a buffer until a later frame. Data may not be returned until frame F+1 or later.

[0053] In a more substantial example, hundreds of EDs may exist on each RM branch. Numerous RM units may exist. TDMA packets incur overhead in the form of preambles, addresses, error checking, and other non-payload data. Therefore, longer packets with larger payloads are more efficient. Having multiple RM / ED channels allows many RM / ED data transfers to occur simultaneously, increasing communication efficiency. By matching results in RM units 505a-505c, subsequent RM / RD packets can contain more data in longer payloads, further increasing communication efficiency. Furthermore, the exemplary embodiments described herein maintain a deterministic protocol across all levels, as well as synchronization across all levels, by using separate TDMA schedules at different architectural levels.

[0054] There are many ways to assemble a frame. For example, a more complex TDMA timing diagram may be used. Here, RM communication to RD unit 503 and ED is interleaved to increase throughput. Also, slots for retries and different responses from different nodes in different frames are incorporated.

[0055] Figure 8 illustrates a more complex example. Slots 1-6 in Figure 8 are similar to those described in relation to Figure 7. Slot 7 in Figure 8 is used for retries, where a previously transmitted packet, presumably having failed to be received due to corruption, is resent to the respective RM unit. This requires a communications controller that can sort what is sent and when, frame by frame. A packet from ED1:1 sent to RM505a in slot 7 could be a failed packet from the previous frame, while a retry of ED3:3 in slot 15 could be due to a failure in slot 6. Similarly, there could be retries of packets sent from RM units 505a-505c to RD unit 503, as shown in slots 8 and 16. By providing a sufficient number of retry slots, it is possible to ensure that packets pass through with any high probability.

[0056] According to some of the exemplary embodiments, multiple frames may be combined into a superframe. If necessary, all EDs may be communicated over a single superframe. In some networks, a single frame may be sufficient to communicate with all EDs, while in larger networks, multiple frames may be required.

[0057] At the start of a frame, some assumptions may or may not be made regarding the synchronization of the clocks of all RM and ED nodes. While residual synchronization of the clocks may exist on all nodes remaining from the previous frame, if they are not synchronized, the clocks will diverge, and the spread will increase over time. Ultimately, nodes will transmit and receive too early or too late, and measurements will be taken at a wide range of times.

[0058] The system in Figure 5 features a three-level architecture, but it should be understood that such a configuration is merely an example. According to exemplary embodiments, multiple layers of RM units may be used, resulting in communication systems featuring more than three levels. Figure 9 provides an example of a communication system featuring four architectural levels. Specifically, the system in Figure 9 features a first level of various ED groupings and a second level for a first RM unit (RM1), where one RM1 unit is associated with each ED grouping. The system in Figure 9 further comprises a third architectural level featuring several second RM units (RM2), where one RM2 unit is associated with each RM1 unit grouping. Finally, a fourth architectural level is provided, where an RD unit (RD1) communicates directly with all of the RM2 units. The system in Figure 9 is shown merely as an example, and it should be understood that the communication systems described herein may include any number of architectural layers (i.e., any number of three or more layers). The configurations illustrated in Figure 9 include multiple levels that allow the communication architecture to match any arbitrary cell / module / pack architecture. It should be understood that, according to some of the exemplary embodiments, RM2 may manage a single pack (or any number of packs) rather than the multiple packs illustrated in the examples provided in Figure 9.

[0059] The description of the exemplary embodiments provided herein is presented for illustrative purposes only. The description is not intended to be comprehensive or to limit the exemplary embodiments to the exact forms disclosed, and modifications and variations may be possible in light of the teachings above or obtained from the practice of various alternatives to the provided embodiments. The examples considered herein are selected and described to illustrate the principles and properties of various exemplary embodiments and their practical applications, enabling those skilled in the art to utilize the exemplary embodiments in various modes and with various modifications to suit a particular intended use. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be understood that the exemplary embodiments presented herein may be practiced in any combination with one another.

[0060] It should be noted that the word “including” does not necessarily exclude the existence of other elements or steps other than those listed, and the words “a” or “an” preceding an element do not exclude the existence of multiple such elements. It should be further noted that any reference numerals are not intended to limit the scope of the claims, exemplary embodiments may be implemented at least partially by both hardware and software, and some “means,” “units,” or “devices” may be represented by the same hardware items.

[0061] The various exemplary embodiments described herein are described in the general context of steps or processes of a method, and in one aspect may be implemented by a computer program product embodied on a computer-readable medium, including computer-executable instructions such as program code executed by a computer in a network environment. The computer-readable medium may include, but is not limited to, removable and non-removable storage devices, including read-only memory (ROM), random access memory (RAM), compact discs (CDs), and digital versatile discs (DVDs). Generally, a program module may include routines, programs, objects, components, data structures, etc., that perform a particular task or implement a particular abstract data type. Computer-executable instructions, associated data structures, and program modules illustrate examples of program code for performing steps of the methods disclosed herein. A particular sequence of such executable instructions or associated data structures illustrates an example of a corresponding action for performing the function described in such steps or processes.

[0062] Exemplary embodiments are disclosed in the drawings and specification. However, many variations and modifications can be made to these embodiments. Therefore, although specific terms are used, they are used only in a general and descriptive sense and not for limiting purposes, and the scope of the embodiments is defined by the following claims.

Claims

1. A communication system for monitoring an electric battery system, wherein the communication system is A single time-division multiplex access, TDMA, protocol that operates across the aforementioned communication system, A plurality of electronic devices located at a first level of the communication system, each electronic device configured to acquire measurements on at least one battery cell of the electric battery system, and the plurality of electronic devices are arranged in at least two subgroups of electronic devices, At least two wireless manager units located at a second level of the communication system, wherein each subgroup of electronic devices communicates with the respective wireless manager unit via a first TDMA schedule and a first communication medium, The communication system comprises at least one wireless director unit located at a third level, wherein each wireless manager unit and the at least one wireless director unit communicate via a second TDMA schedule and via a second communication medium, A communications system in which at least one wireless director unit is configured to determine the second TDMA schedule, each wireless manager unit is configured to determine the respective first TDMA schedule, and the first and respective second TDMA schedules define the timing for reporting and command messaging based on measurements across the entire communications system in a synchronized manner.

2. The communication system according to claim 1, wherein the first and second communication media are equivalent, or the first and second communication media are separate.

3. The communication system according to claim 2, wherein the communication type is long-range wireless, short-range wireless, optical medium, or electromagnetic medium.

4. The communication system according to claim 3, wherein the first communication medium is short-range wireless and the second communication medium is long-range wireless.

5. The communication system according to any one of claims 1 to 4, wherein the at least one wireless manager unit includes a mechanism for switching between the first communication medium and the second communication medium.

6. The communication system according to claim 5, wherein the mechanism is an antenna switch.

7. The at least one wireless director unit is configured to send a broadcast message to each of the at least two wireless manager units. The communication system according to any one of claims 1 to 6, wherein each of the at least two wireless manager units is configured to extract each portion of the broadcast message via a unique identifier associated with each wireless manager unit.

8. The communication system according to any one of claims 1 to 7, wherein each of the plurality of electronic devices is configured to simultaneously measure at least one of its battery cells according to the first TDMA schedule.

9. The communication system according to any one of claims 1 to 8, wherein the first TDMA schedule includes at least one time frame for retry measurement for any of the plurality of electronic devices.

10. The communication system according to any one of claims 1 to 9, wherein the communication system is located within an electric battery storage facility or an electric vehicle.

11. A method in a communication system for monitoring an electric battery system, wherein the communication operates across a single time-division multiplex access, TDMA, protocol, and the method Determining a first TDMA schedule for communication between a plurality of electronic devices and at least two wireless manager units via a first communication medium, wherein the plurality of electronic devices are located at a first level of the communication system and are arranged in at least two subgroups of electronic devices, and the at least two wireless manager units are located at a second level of the communication medium. Determining a second TDMA schedule for communication between the at least two wireless manager units and the at least one wireless director unit via a second communication medium, wherein the at least one wireless director unit is located at a third level of the communication system. To acquire measurements on at least one battery cell of the electric battery system via the plurality of electronic devices, The acquired measurement values ​​are transmitted to at least two wireless manager units via the first TDMA schedule and via the first communication medium. This includes further transmitting the acquired measurement values ​​to at least one wireless director unit via the second TDMA schedule and the second communication medium, A communications system in which at least one wireless director unit is configured to determine the second TDMA schedule, each wireless manager unit is configured to determine the respective first TDMA schedule, and the first and respective second TDMA schedules define the timing for reporting and command messaging based on measurements across the entire communications system in a synchronized manner.

12. The method according to claim 11, further comprising switching between the first communication medium and the second communication medium within the at least two wireless manager units.

13. The method described above is Sending a broadcast message to each of the at least two wireless manager units via the at least one wireless director unit, The method according to any one of claims 11 to 12, further comprising retrieving each portion of the broadcast message by a unique identifier associated with each of the at least two wireless manager units.

14. The method according to any one of claims 11 to 13, further comprising obtaining the measurement values ​​by simultaneously measuring each at least one battery cell via the plurality of electronic devices in accordance with the first TDMA schedule.

15. A computer-readable medium for storing instructions that cause the communication system to perform the method according to any one of claims 11 to 14, when executed by the processor of the communication system for an electronic battery system.

Images