System parameter low power monitoring method

Abstract

Battery monitoring techniques that consume low power are described herein. The battery monitoring techniques can be used when a host device (e.g., an electric vehicle) is not in operation, thereby providing time to use low power techniques. A measurement device can measure system parameters while the host processor is off or in a low power mode using a heartbeat (HB) sequencing technique. Based on the HB messages, the host processor can be alerted and awakened when a fault is detected.

Description

[0001] Claiming priority

[0002] This patent application claims priority to U.S. Provisional Patent Application Serial No. 63 / 086314, filed October 1, 2020, entitled “Low Power Monitoring Method for System Parameters,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to low-power monitoring of batteries in a battery management system (BMS). Background Technology

[0004] Typically, the BMS in an electric vehicle (EV) monitors the battery pack while the EV is running (e.g., when it is in the "on" or "accessory" position, or while it is charging). However, defects or damage in the battery cells can cause abnormal phenomena such as thermal runaway or malfunctions, even when the EV is not running, such as when it is parked, turned off, or disconnected from the charging source.

[0005] Therefore, the ability to monitor the battery pack during extended periods of inactivity is required. One approach is to use continuous battery monitoring techniques, but these typically consume significant amounts of power. Periodic monitoring managed by a (relatively high-power) host processor can lead to considerable / undesirable state-of-charge degradation, as the host processor's power consumption is significant even at low duty cycles. Attached Figure Description

[0006] The accompanying drawings illustrate only exemplary embodiments of this disclosure and should not be construed as limiting its scope.

[0007] Figure 1 A block diagram of a battery management system (BMS) is shown.

[0008] Figure 2 A block diagram of a wired battery management system is shown, which illustrates a block diagram of a BMS with bridging devices.

[0009] Figure 3 A block diagram of a BMS with bridging devices operating in a reduced energy consumption mode is shown.

[0010] Figure 4 The timing diagram for BMS monitor operation is shown.

[0011] Figure 5 An example of the structure of an HB message is shown.

[0012] Figure 6 A block diagram of a BMS with redundant components is shown.

[0013] Figure 7The BMS monitor is shown as a monitor, manager, and timeout monitor. Detailed Implementation

[0014] This document describes a low-power battery monitoring technique. Battery monitoring techniques can be used when the host application (e.g., an EV) is not running, thus providing the benefits of using low-power technologies. The battery monitoring technique described herein can employ a host processor, multiple measurement devices, and optional bridging devices to monitor system parameters. The host processor may consume a significant amount of power relative to the measurement devices and bridging devices; therefore, when the host processor is off or in a low-power mode (e.g., sleep mode), the measurement devices can use a heartbeat (HB) sequencing technique to measure system parameters. HB messages generated by the HB sequencing technique can include information about each battery module coupled to the measurement devices. Based on the HB messages, the host processor may be alerted and woken up (or powered on) when a fault is detected.

[0015] This disclosure describes a method for monitoring a battery using multiple monitors in a reduced power consumption mode. At a first monitor: transitioning from a reduced power consumption state; performing a first measurement on a first battery module coupled to the first monitor; generating a heartbeat message; encoding information about the first measurement into the heartbeat message; adjusting a count in the heartbeat message in response to no error detected by the first monitor, and not adjusting the count in response to an error detected by the first monitor; sending the heartbeat message to a second monitor; and re-entering the reduced power consumption state. At a second monitor: receiving the heartbeat message from the first monitor; performing a second measurement on a second battery module coupled to the second monitor; encoding information about the second measurement into the heartbeat message; adjusting a count in the heartbeat message in response to no error detected by the second monitor, and not adjusting the count in response to an error detected by the second monitor. At a watchdog device: receiving the heartbeat message; and determining, based on the count in the heartbeat message, whether to generate an alarm for the host processor.

[0016] This document also describes a method for monitoring a battery module in a reduced power consumption mode, the method comprising: transitioning to a reduced power consumption state; transitioning from the reduced power consumption state and initiating a heartbeat sequence based on a timer, the heartbeat sequence comprising performing measurements on the battery module and comparing the measurements with a threshold; encoding a heartbeat message based on the comparison of the measurements with the threshold; determining whether an error condition exists; adjusting a count in the heartbeat message in response to no error condition being determined, and not adjusting the count in response to determining the error condition; sending the heartbeat message to another monitor; and re-entering the reduced power consumption state.

[0017] This document further describes a battery management system including a host processor, multiple monitors coupled to various battery modules of a battery, and a watchdog device coupled to the multiple monitors. The watchdog device is configured to: receive a heartbeat message including measurement information from the multiple monitors and a count value indicating the number of monitors experiencing an error condition; generate an alarm for the host processor to exit a reduced power consumption mode in response to the count value indicating that at least one monitor is experiencing the error condition; and maintain the host processor in the reduced power consumption mode in response to the count value indicating that no monitor is experiencing the error condition.

[0018] Figure 1 A block diagram of a battery management system (BMS) 100 is shown. The BMS 100 may include multiple battery modules 102.1-102.n, each including multiple battery cells. For example, battery modules 102.1-102.n may be lithium-ion batteries. Batteries of different specifications, sizes, and shapes can be used. Each module can be coupled to its respective monitor 104.1-104.n.

[0019] Each monitor 104.1-104.n can be coupled to a corresponding battery module 102.1-102.n and can monitor various conditions or performance of the battery module 102.1-102.n. As an illustrative example, each monitor 104.1-104.n can be provided as an integrated circuit, which may include a monolithic integrated BMS circuit or an integrated module, including multiple integrated circuit dies or other circuit elements within a common shared integrated circuit device package.

[0020] Monitors 104.1-104.n can include various sensors. Monitors 104.1-104.n can sample battery voltage to monitor battery levels. Monitors 104.1-104.n can also monitor the current and external surface temperature of the battery module.

[0021] In this example, monitors 104.1-104.n can communicate with the host processor 106 via a wired communication interface. For example, the communication interface may include an isolated (transformer) communication cable, such as implementing an Isolated Serial Peripheral Interface (isoSPI). The communication cable can be connected serially from one module to another, for example, from monitor to monitor (104.1-104.n), where the last BMS monitor (e.g., 104.n) provides the termination point for the wiring.

[0022] Figure 2A block diagram of a BMS 200 with a bridging device is shown. The BMS 200 may include multiple battery modules 102.1-102.n coupled to multiple monitors 104.1-104.n, as described above. The BMS 200 may also include a host processor 106, as shown above. The BMS 200 may also include a bridging device 208. The bridging device 208 may be placed between the host processor 106 and the first monitor 104.1. For example, the first monitor 104.1 may be coupled to the bridging device 208 via isoSPI, and the bridging device 202 may in turn be coupled to the host processor 106 via SPI.

[0023] Figure 3 A block diagram of a BMS 300 with a bridging device operating in a reduced power consumption mode is shown. The BMS 300 may include multiple monitors 304.1-304.4, a host processor 306, a bridging device 308, and a power supply 310. The four monitors 302.1-302.4 are for illustrative purposes only; other numbers of monitors may be used. Here, one of the monitors may be configured to also operate as a manager (also referred to as monitor / manager 304.4). Monitor / manager 304.4 may be located at the opposite end of the host processor 306 in a daisy chain. During the reduced power consumption mode, monitors 304.1-304.4, as well as the host processor 306 and the bridging device 308, can operate in a reduced power consumption state.

[0024] During reduced power consumption mode, monitor / manager 304.4 can initiate a measurement sequence (also known as an HB message sequence) based on a schedule at defined time intervals (referred to as HB intervals). Monitor / manager 304.4 can use an HB timer, and when the timer expires, it can wake up from its reduced power consumption state and begin performing various measurements of system parameters on its coupled battery modules or cells. Monitor / manager 304.4 can compare these measurements with predefined thresholds. After monitor / manager 304.4 has completed its measurements and comparisons, it can send a communication message to the next monitor 304.3 in the communication chain, and then return to its reduced power consumption state and restart its HB timer. The timing of the HB timer can be configurable (e.g., every 1-60 seconds). Furthermore, the HB message sequence can utilize the same communication link used during normal high-power operation mode to communicate with monitors 304.1-304.4. HB message delivery may not require additional communication paths.

[0025] Communication messages can be encoded into recognizable commands. These commands can wake up the next monitor (e.g., 304.3) and cause it to initiate the same measurement and comparison operations. The command message can also include information about the measurements and comparisons performed by monitor / manager 304.4. The receiving monitor 304.3 can then add its measurement and comparison results to the message and send it to the next monitor 304.2, and the sequence can continue until the last monitor 304.1 completes its sequence.

[0026] If any measurement value from any monitor 304.1-304.4 exceeds a predefined threshold, the corresponding monitor can set a flag bit or bit field high in the message. Similarly, if monitors 304.1-304.4 experience a self-diagnostic error, a flag or bit field can be set in the message. The message can also contain information about the count of devices that have successfully completed measurements and comparisons without exceeding any thresholds or experiencing any diagnostic errors. Monitors 304.1-304.4 can decrement the device counter if the device counter has not experienced any errors, and may not decrement the device counter if the device counter is experiencing some type of error (e.g., exceeding a threshold or a diagnostic error).

[0027] After the measurement sequence has passed through all monitors, the watchdog device can receive the HB message. The watchdog device can be implemented as a separate bridging device 308 (e.g., Figure 3 (As shown). Alternatively, the last monitor 304.1 can be configured as a watchdog device. The watchdog device can receive communication messages and can analyze the content of the messages. Typically, the watchdog device will expect no indication of exceeding a threshold or diagnostic error, and expect the device count to indicate that all monitors have successfully performed the measurement and comparison. However, if the message includes an indication that one or more monitors are displaying an error, the watchdog device will (e.g., via bridging device 308) alert the host processor 306. For example, the watchdog device can send an interrupt signal to the host processor to wake it from sleep mode. In another example, the watchdog device can send an enable signal to power supply 310 to power the host processor. Thus, the host processor 306 can query monitors 304.1-304.4 for more information about the detected error.

[0028] In addition, the watchdog device may also include a timer (e.g., a timeout monitor) that can alert the main processor by waking up or powering on if the watchdog device does not receive an HB message within a predefined time (e.g., watchdog timeout).

[0029] Figure 4A timing diagram for BMS monitor operation is shown. Four monitors 404.1-404.4 are shown here, but other numbers of monitors can also be used. Monitor 404.4 (e.g., a monitor at the opposite end of a daisy chain) can also be configured as a manager, as described above. Monitor / manager 404.4 can operate in a reduced power consumption state, after which the HB timer can pass. During this programming interval, monitor / manager 404.4 can be powered on and its reference enabled. Next, cell measurement, conversion, and comparison (ADCV) can be performed.

[0030] At this point, Monitor / Manager 404.4 can also send a wake-up pulse to the next Monitor 404.3. Monitor 404.3 can receive the wake-up pulse and power on its isoSPI. Simultaneously, Monitor / Manager 404.4 can perform GPIO measurement, conversion, and comparison (AD AX). Monitor / Manager 404.4 can then generate an HB command, as described herein, which carries the results of the measurement, conversion, and comparison. If no threshold is violated, Monitor / Manager 404.4 can send an HB message without raising a flag. If a threshold is violated, Monitor / Manager 404.4 can send an HB message with an appropriate flag raised (e.g., a fault signal). If Monitor / Manager 404.4 does not raise a flag, it can also decrement the device counter. If a flag is raised, Monitor / Manager 404.4 can avoid decrementing the device counter. Monitor / Manager 404.4 can send commands to the next Monitor 404.3 via isoSPI. Monitor / Manager 404.4 can then re-enter a reduced power consumption state.

[0031] Monitor 404.3 and other monitors 404.2, 404.1 can continue the HB sequence, as shown, until the last monitor 404.2 completes its partial sequence. Each monitor can maintain a flag triggered by any previous device. The HB messages can then be analyzed by a watchdog device (such as a bridging device or the last monitor 404.1).

[0032] The host processor can initiate a low-power mode (also known as Low-Power Cell Monitoring (LPCM)) to instruct the device to enter low-power mode. The host processor can also enter low-power mode. In one example, the host processor can remain in operational mode for the first one or more cycles of HB message passing to ensure message passing is operable. After receiving the first or more successful HB messages, the host processor can then enter low-power mode.

[0033] Figure 5An example of the structure of an HB message is shown. The payload of the HB message is shown here. In this example, the following thresholds can be provided for monitoring: positive GPIO Δ voltage (CMF_GDVP); negative GPIO Δ voltage (CMF_GDVN); GPIO overvoltage (CMF.GOV); GPIO undervoltage (CMF.GUV); positive battery Δ voltage (CMF.CDVP); negative battery Δ voltage (CMF.CDVN); battery overvoltage (CMF...COV); and battery low voltage (CMF.CUV).

[0034] When a monitor encounters any of these situations, it may raise the corresponding flag in the HB message payload. Each monitor can maintain flags issued by any previous device.

[0035] Before entering the reduced power mode, the host processor can configure the thresholds used for each monitor. In one example, the host processor can effectively disable OV and Δ voltage positive comparisons by setting those thresholds to their maximum values. Similarly, the host processor can effectively disable UV and Δ voltage negative comparisons by setting these thresholds to their minimum values. To mask unused channels, one bit can be provided for each cell channel and each GPIO channel to disable all comparisons for that channel.

[0036] The payload of the HB message can also include a device count, initiated by the manager, which is decremented for each monitor if all monitoring transitions complete without failure and without threshold violations. Therefore, when the HB message arrives at the host processor upon its wake-up or power-on state, the host processor can determine how many devices are reporting a certain error based on the device count. For example, if the system comprises eight devices and the device count in the HB message does not decrease three times, the host processor can determine that three devices have experienced a fault / error or threshold crossing. In another example, a watchdog device can compare the final device count to an expected value, and if the final device count does not match the expected value, it can alert the host processor.

[0037] Redundancy can be built into the system. Redundancy can mitigate potential component / wiring failures. Figure 6 A block diagram of a BMS 600 with redundant components is shown. The BMS 600 may include multiple monitors 604.1-604.6, a host processor 606, a first bridging device 608.1, a second bridging device 608.2, and a power supply 610. The six monitors 602.1-602.6 are for illustrative purposes only; other numbers of monitors may be used.

[0038] Here, for one form of redundancy, two bridging devices 608.1 and 608.2 can be provided to form two reversible connections with monitors 604.1-604.6. In one example, the BMS 600 can operate as two single chains, with each bridging device operating with a separate manager / monitor. Two separate managers can be configured at the end of each chain. Each of the bridging devices 608.1 and 608.2 can receive HB messages or time out during reduced power consumption modes, as described herein. If an HB message indicates a fault or a timeout, the corresponding bridging device 608.1 or 608.2 can accordingly alert the host processor 606.

[0039] Furthermore, in the event of an isoSPI bus interruption, such as between monitors 604.3 and 604.4, as described above, the corresponding bridging devices 608.1 and 608.2 used due to watchdog timeout can issue an alarm to the host processor 606. In response, the host processor 606 can wake up and diagnose the bus interruption location, and reconfigure the dual-bridging device chain into two single-bridging device chains. Thus, for monitors 604.1-604.3 on one side of the isoSPI interruption, a first bridging device 608.1 can be used to form a first chain. For monitors 604.4-604.6 on the other side of the isoSPI interruption, a second bridging device 608.2 can be used to form a second chain. In this example, the opposite end monitors on each side of the isoSPI interruption (e.g., monitor 604.3 of the first chain and monitor 604.4 of the second chain) can also be reconfigured as managers.

[0040] Furthermore, a second form of redundancy can be provided in the event of a bridging device failure. Here, the monitors at the end of the battery stack (e.g., monitors 604.1 and / or 604.6) can also be configured to operate as bridging device emulators. As described herein, these monitors can be configured to operate as watchdog devices. Here, the GPIOs of these monitors can be configured as interrupt pins of the host processor 606 and / or power supply 610.

[0041] Figure 7A BMS monitor operating as a monitor, manager, and timeout monitor is illustrated. Here, monitor 704 can be coupled to host processor 706 and power supply 710. Monitor 704 can be configured to function as a battery monitor to perform measurements, conversions, and comparisons as described herein. Monitor 704 can also be configured to operate as a manager to initiate HB sequences, as described herein. Furthermore, as described herein, monitor 704 can be configured to operate as a timeout monitor (or watchdog device) to analyze HB messages and alert host processor 706 when necessary. For example, GPIO pins of monitor 704 can be configured as interrupt pins for host processor 706 and / or power supply 710.

[0042] The battery monitoring technology described in this paper provides rapid and accurate transmission of battery health status while consuming low amounts of power. The technology allows the host processor to remain in a shutdown or low-power mode until a fault is detected. Furthermore, the monitoring has minimal impact on battery voltage, which has extremely low supply current.

[0043] Various annotations

[0044] Each of the above non-limiting aspects may exist independently or may be combined with one or more other aspects or other topics described in this document in various permutations or combinations.

[0045] The above detailed description includes references to the accompanying drawings, which form part of the detailed description. The drawings illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These implementations are generally also referred to as “examples.” Such examples may include elements other than those shown or described. However, the inventors also contemplate examples that provide only those elements shown or described. Furthermore, the inventors also contemplate examples using any combination or arrangement of the shown or described elements (or one or more aspects thereof), or other examples (or one or more aspects thereof) shown or described herein.

[0046] If there is any inconsistency between the usage in this document and any other document merged by reference, the usage in this document shall prevail.

[0047] In this document, the terms “a” or “an” are common in patent documents and include one or more, independent of any other instance or use of at least one or “a more”. In this document, the term “or” is used to refer to non-exclusivity, and unless otherwise stated, “A or B” includes “A but not B”, “B but not A”, and “A and B”. In this document, the terms “comprising” and “wherein” are used as their plain English equivalents to the corresponding terms “comprising-” and “including”. Furthermore, in the following claims, the terms “comprising” and “including” are open-ended, meaning that a system, apparatus, article, composition, formulation, or method comprising elements other than those listed after the term in the claim is still considered to fall within the scope of that claim. Furthermore, in the following claims, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their objects.

[0048] The methods described herein may be implemented, at least in part, by a machine or computer. Some examples may include a computer-readable or machine-readable medium encoded with instructions that can be used to configure an electronic device to perform the methods described in the examples above. Implementations of these methods may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, for example, during execution or at other times. Examples of such tangible computer-readable media may include, but are not limited to, hard disks, removable disks, removable optical discs (e.g., optical discs and digital video discs), magnetic tape cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0049] The above description is intended to be illustrative and not restrictive. For example, the examples (or one or more aspects thereof) described above may be used in combination with each other. Other implementations may be used, for example, by those skilled in the art upon review of the above description. An abstract is provided to allow the reader to quickly determine the nature of the technical disclosure. It should be understood that this document is not intended to interpret or limit the scope or meaning of the claims. Furthermore, in the detailed description above, various features may be grouped together to simplify this disclosure. This should not be construed as meaning that unclaimed features of the disclosure are essential to any claim. Rather, the subject matter of the invention may not be limited to all features of an implementation of a particular disclosure. Therefore, the following claims are incorporated herein as examples or implementations, wherein each claim is an independent, separate implementation, and these implementations are contemplated to be combined with each other in various combinations or arrangements. The scope of the invention should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A method for monitoring a battery using multiple monitors in a power-saving mode, the method comprising: At the first monitor designated as the manager monitor: Based on the shift from a state of reduced energy consumption in scheduling; A first measurement is performed on the first battery module coupled to the first monitor; Generate heartbeat messages; Information about the first measurement is encoded into the heartbeat message; If no error is detected by the first monitor, the count in the heartbeat message is adjusted; if an error is detected by the first monitor, the count is not adjusted. The heartbeat message is sent to the second monitor; and Re-entering a state of reduced energy consumption; At the second monitor: In response to an indication received from the first monitor, the system transitions from a reduced energy consumption state; Receive the heartbeat message from the first monitor; A second measurement is performed on the second battery module coupled to the second monitor; Information about the second measurement is encoded into the heartbeat message; If the second monitor does not detect an error, the count in the heartbeat message is adjusted; if the second monitor detects an error, the count is not adjusted. At the watchdog device: Receive the heartbeat message; and Based on the count in the heartbeat message, determine whether to generate an alarm for the host processor.

2. The method of claim 1, wherein the heartbeat message is transmitted between the first monitor and the second monitor using an isolated serial peripheral interface.

3. The method of claim 1, wherein performing the first measurement includes detecting an overvoltage condition.

4. The method of claim 1, wherein performing the first measurement includes detecting an undervoltage condition.

5. The method of claim 1, wherein performing the first measurement includes detecting a Δ voltage condition.

6. The method of claim 1, wherein the information regarding the first measurement includes whether the measurement characteristics of the first battery module are outside a specified range.

7. The method of claim 1, wherein the watchdog device is a third monitor.

8. The method of claim 1, wherein the watchdog device is a bridging device between the last monitor and the host processor.

9. A method for monitoring a battery module in a reduced power consumption mode, the method comprising: The manager monitor switches to a reduced power consumption state; The manager monitor, based on a timer, transitions from the reduced energy consumption state and initiates a heartbeat sequence, which includes performing measurements on the battery module and comparing the measurements to a threshold. The manager monitor encodes heartbeat messages based on a comparison of the measurement with the threshold; The manager monitor determines if any error conditions exist; The manager monitor adjusts the count in the heartbeat message in response to the absence of an error condition, and does not adjust the count in response to the determination of the error condition. The manager monitor sends an indication of a transition from a reduced energy consumption state to another monitor; The manager monitor sends the heartbeat message to another monitor; and The manager monitor has re-entered a reduced power consumption state.

10. The method of claim 9, wherein the error condition is triggered by a comparison of the measurement with the threshold.

11. The method of claim 9, wherein the error condition is triggered by a diagnostic error.

12. The method of claim 9, wherein the error condition is triggered by a device counter.

13. A battery management system, comprising: Host processor; Multiple monitors, coupled to the various battery modules of the battery, wherein the first of the multiple monitors is designated as the manager monitor and is configured to transition from a reduced power consumption mode and initiate a heartbeat message based on a timer; and A watchdog device, coupled to the plurality of monitors, is configured to: Receive the heartbeat message, which includes measurement information from multiple monitors and a count value indicating the number of monitors experiencing error conditions; In response to the count value indicating that at least one monitor is experiencing the error condition, an alarm is generated for the host processor to exit the reduced power consumption mode; And in response to the count value indicating that no monitor is experiencing an error condition, the host processor is maintained in the reduced power consumption mode.

14. The battery management system of claim 13, wherein one of the plurality of monitors is configured as the watchdog device.

15. The battery management system of claim 13, wherein the first monitor of the plurality of monitors is configured to: Measurements are performed on the corresponding coupled battery modules and the measurements are compared with thresholds; The heartbeat message is encoded based on a comparison between the measurement and the threshold: Determine if a first error condition exists; In response to the absence of a first error condition, the count value in the heartbeat message is adjusted; and in response to the determination of the first error condition, the count is not adjusted. Send the heartbeat message to the second monitor among the plurality of monitors; and Re-enter the reduced energy consumption mode.

16. The battery management system of claim 15, wherein the first monitor is configured to send a wake-up signal to the second monitor.

17. The battery management system of claim 16, wherein the first monitor is configured to send the wake-up signal to the second monitor before sending the heartbeat message to the second monitor.

18. The battery management system of claim 15, wherein the plurality of monitors communicate using isolated serial peripheral interfaces.

19. The battery management system of claim 15, wherein the measurement information includes detecting overvoltage conditions.

20. The battery management system of claim 15, wherein the measurement information includes detecting undervoltage conditions.

21. The battery management system of claim 15, wherein the measurement information includes detecting Δ voltage condition.

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