Battery monitoring system

Abstract

A battery monitoring system monitors states of a plurality of batteries (C11 to Cmn). The battery monitoring system includes a battery monitoring ECU (10) and a plurality of battery monitoring devices (30, 32, 33). The battery monitoring ECU and the plurality of battery monitoring devices are connected to each other in any connection form of a ring connection, a daisy chain connection, or a multi-point connection.

Description

Technical Field

[0001] This disclosure relates to a battery monitoring system. Background Technology

[0002] In recent years, the number of automobiles using rechargeable batteries has been increasing. The demand for battery monitoring systems (Battery Management Systems (BMS)) that measure the electrical characteristics of rechargeable batteries to obtain their internal state (e.g., the state of charge (SOC) of the rechargeable battery) is increasing. US2019 / 086475A1 (corresponding to CN 109525520 A) discloses a battery monitoring system in which multiple batteries are monitored by multiple battery monitoring ICs, and the multiple battery monitoring ICs are connected in a daisy-chain manner. Such a battery monitoring system is provided with a battery monitoring ECU that performs overall control. When the battery monitoring ECU outputs commands, etc., to the battery monitoring devices at the first layer, each of the multiple battery monitoring devices connected in the daisy-chain manner adds its own data, etc., to the information received from the previous layer, and transmits the information to subsequent layers. The battery monitoring devices at the last layer output all information to the battery monitoring ECU. Each battery monitoring device includes an oscillator, and the battery is measured and monitored by using the oscillation frequency of the oscillator. Summary of the Invention

[0003] In this case, to measure the state of each battery with high accuracy, it is necessary to improve the accuracy of the oscillation frequency of each battery monitoring device. Therefore, a high-precision oscillator, such as a crystal oscillator, is required as the oscillator for the battery monitoring device.

[0004] However, there are difficulties: using high-precision oscillators, such as crystal oscillators, in each battery monitoring device increases cost. In view of the above difficulties, the object of this disclosure is to provide a battery monitoring system that achieves sufficient measurement accuracy without using high-precision oscillators in the battery monitoring device.

[0005] This disclosure solves at least some of the above-mentioned difficulties, and can be implemented through the following embodiments.

[0006] According to one aspect of this disclosure, a battery monitoring system monitors the state of multiple batteries. The battery monitoring system includes a battery monitoring ECU and multiple battery monitoring devices. The battery monitoring ECU and the multiple battery monitoring devices can be connected to each other in any of the following connection methods: ring connection, daisy-chain connection, or multipoint connection. The battery monitoring ECU includes a first clock generator and a transceiver. The first clock generator generates a first clock signal. The transceiver outputs a superimposed signal to at least one of the multiple battery monitoring devices and receives monitoring results of the state of the multiple batteries, wherein battery monitoring information is superimposed on the first clock signal in the superimposed signal. Each of the multiple battery monitoring devices includes a receiver, a second clock generator, a controller, a battery monitor, a frequency monitor, and a transmitter. The receiver receives the superimposed signal from the previous layer. The second clock generator generates a second clock signal as a reference for the operation of the corresponding battery monitoring device. The controller extracts the clock of the superimposed signal from the previous layer as a reference clock signal and recovers the battery monitoring information. The battery monitor monitors the state of one or more batteries corresponding to the battery monitoring device by using the second clock signal and the battery monitoring information. The frequency monitor monitors the difference between the frequency of the reference clock signal and the frequency of the second clock signal. The transmitter outputs battery monitoring information, monitoring results up to the current layer, and difference information indicating the difference up to the current layer to subsequent layers.

[0007] Through the aforementioned battery monitoring system, the controller of the battery monitoring ECU can acquire the frequency error of the second clock signal of the battery monitoring device at each layer relative to the first clock signal, and monitor the oscillation frequency information of all oscillators. The controller can then determine how much the frequency of the second clock signal of the battery monitoring device at which layer needs to be corrected.

[0008] This disclosure can also be implemented in various ways. For example, in addition to a battery monitoring system, this disclosure can also be implemented as a battery monitoring method, etc. Attached Figure Description

[0009] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings:

[0010] Figure 1 This is a schematic configuration diagram of the battery monitoring system according to the first embodiment.

[0011] Figure 2 This is a flowchart of the process executed by the controller of the battery monitoring ECU.

[0012] Figure 3 This is a flowchart of the operations performed by the controller of the battery monitoring device.

[0013] Figure 4This is an illustration of the first superimposed signal sent by the battery monitoring ECU and the second superimposed signal sent and received by the battery monitoring device.

[0014] Figure 5 This is a schematic configuration diagram of the battery monitoring system according to the second embodiment.

[0015] Figure 6 This is a schematic configuration diagram of the battery monitoring system according to the third embodiment. Detailed Implementation

[0016] (First Embodiment)

[0017] (Configuration of Battery Monitoring System 100)

[0018] like Figure 1 As shown, the battery monitoring system 100 includes a battery monitoring electronic control unit (ECU) 10 and a plurality of (m in this embodiment, where m is an integer of 2 or greater) battery monitoring devices 30. The battery monitoring devices 30 in the x-th layer (x is an integer from 1 to m) monitor the battery state of each of the n (n is an integer of 1 or greater) secondary batteries (hereinafter referred to as "batteries") contained in the battery pack CSx in the x-th layer. Therefore, the battery monitoring system 100 monitors the battery state of each of a plurality of (m×n in this embodiment) batteries C11 to Cmn. In this embodiment, the number of batteries monitored by the battery monitoring devices 30 at each layer is the same as n, but the number of batteries monitored by the battery monitoring devices 30 at each layer can also be different.

[0019] The battery monitoring ECU 10 includes two connectors 18 and 20, and each battery monitoring device 30 includes two connectors 34 and 36. The battery monitoring ECU 10 and the multiple battery monitoring devices 30 are connected in a ring to each other. That is, one connector 18 of the battery monitoring ECU 10 is connected to one connector 34 of the battery monitoring device 30 on the first layer via transmission path 22. Another connector 36 of the battery monitoring device 30 on the first layer is connected to one connector 34 of the battery monitoring device 30 on the second layer via transmission path 24. Another connector 36 of the battery monitoring device 30 on the second layer is connected to one connector 34 of the battery monitoring device 30 on the third layer via transmission path 25. Then, up to the last layer of battery monitoring devices 30, another connector 36 of the battery monitoring device 30 on the previous layer is connected to one connector 34 of the battery monitoring device 30 on the current layer via transmission path. Another connector 36 of the battery monitoring device 30 on the m-th layer, which is the last layer, is connected to another connector 20 of the battery monitoring ECU 10 via transmission path 26. In this way, the battery monitoring ECU 10 and the multiple battery monitoring devices 30 are interconnected to form a ring.

[0020] Although details will be described later, the battery monitoring ECU 10 operates based on a first clock signal generated by a first clock generator 12 included in the battery monitoring ECU 10, and the battery monitoring device 30 operates based on a second clock signal generated by a second clock generator 50 included in the battery monitoring device 30. When a command to correct the second clock signal is received from the battery monitoring ECU 10, the controller 48 of the battery monitoring device 30 causes the second clock generator 50 to correct the frequency of the second clock signal so that the frequency of the second clock signal is synchronized with or closer to the frequency of the first clock signal.

[0021] The configuration of the battery monitoring ECU 10 and the battery monitoring device 30 will be described below.

[0022] The battery monitoring ECU 10 internally includes a CPU, ROM, RAM, I / O, buses for connecting these components, etc. (not shown). Each process in the battery monitoring ECU 10 can be software processing, where the CPU executes a program pre-stored in a tangible memory device such as ROM (i.e., a readable, non-transitory tangible recording medium), or hardware processing, where the CPU executes the program. The battery monitoring ECU 10 corresponds to a battery monitoring processor. The battery monitoring ECU 10 includes a first clock generator 12, a host controller 14, a transceiver 16, and the aforementioned connectors 18 and 20. The first clock generator 12 generates a first clock signal that serves as the basis for the operation of the battery monitoring ECU 10. The first clock generator 12 generates the first clock signal as a high-precision clock signal using a crystal oscillator. The first clock generator 12 can use an oscillator other than a crystal oscillator, such as a silicon MEMS oscillator. Furthermore, the first clock generator 12 can receive signals generated by a GNSS reference frequency generator from a GNSS satellite and generate the first clock signal.

[0023] The host controller 14 generates a first superimposed signal (in which battery monitoring information is superimposed on a first clock signal) and sends the first superimposed signal to the transceiver 16. The battery monitoring information includes information specifying the battery to be monitored by the battery monitoring device 30 and a correction instruction indicating whether the battery monitoring device 30 should correct the frequency of the second clock signal. Specifying the battery to be monitored in the battery monitoring information indicates which battery to monitor. The battery to be monitored can be a specific battery in a specific group, a specific number of batteries in a specific group, all batteries in a specific group, or all batteries in all groups. The correction instruction includes information about which battery monitoring device 30's second clock signal should be corrected, i.e., information specifying the battery monitoring device 30 to be corrected. In this embodiment, the correction instruction includes information indicating how much to correct the frequency of the second clock signal, i.e., the amount of correction of the frequency of the second clock signal in the battery monitoring device 30 to be corrected.

[0024] Battery monitoring information is superimposed on the first clock signal using, for example, phase encoding with Manchester code. Battery monitoring information can also be superimposed using methods other than phase encoding with Manchester code, such as phase shift keying.

[0025] Transceiver 16 outputs battery monitoring-related commands to at least one battery monitoring device 30 and receives the results of those commands from at least one battery monitoring device 30. Transceiver 16 generates a differential signal from a first superimposed signal and transmits the differential signal to transmission path 22 via connector 18. The differential signal is obtained by converting one signal into two signals that are inverted relative to each other. Each of transmission paths 22 and 26 connecting the battery monitoring ECU 10 and the battery monitoring device 30, and each of transmission paths 24, 25… connecting one battery monitoring device 30 and another adjacent battery monitoring device 30, has two signal lines. Transceiver 16 sends the original signal to one of the two signal lines of transmission path 22 and sends an inverted signal, in which H and L are reversed from the original signal on one signal line, to the other signal line. Connector 18 includes a capacitor and connects transceiver 16 and transmission path 22 via the capacitor. Therefore, connector 18 transmits only the AC component of the differential signal and not the DC component.

[0026] Transceiver 16 receives a differential signal of a second superimposed signal (which superimposes battery monitoring information, battery monitoring results up to the previous layer in battery monitoring device 30, and difference information of the second clock signal up to the previous layer in battery monitoring device 30) from battery monitoring device 30 on the last layer via transmission path 26 and connector 20, and transceiver 16 recovers the second superimposed signal. The battery monitoring results are the result of battery monitoring processing performed based on battery monitoring information received by each battery monitoring device 30 from battery monitoring ECU 10, and include information specifying the monitored batteries up to the previous layer and measurements of the state of the batteries monitored by battery monitoring devices up to the previous layer. The difference information of the second clock signal of battery monitoring device 30 is information indicating the difference between the frequency of the second clock signal of battery monitoring device 30 and the clock signal of the device on the previous layer. The difference information of the second clock signal will be described later. Similar to connector 18, connector 20 includes a capacitor and connects transmission path 26 and transceiver 16 via the capacitor. Connector 20 transmits only the AC component of the differential signal and not the DC component of the differential signal. Note that in addition to capacitors, connectors 18 and 20 may also include transformers.

[0027] The battery monitoring device 30 includes a battery monitoring integrated circuit (IC) 40, a filter 60, and the aforementioned connectors 34 and 36. The battery monitoring IC 40 includes a receiver 42, a transmitter 44, a controller 48, a second clock generator 50, a frequency monitor 53, and a battery monitor 54. The receiver 42 is connected to connector 34, and the transmitter 44 is connected to connector 36. The controller 48 is connected to the receiver 42 and the transmitter 44. The second clock generator 50, the frequency monitor 53, and the battery monitor 54 are connected to the controller 48. The battery monitor 54 is connected to the battery via the filter 60.

[0028] The receiver 42 of the battery monitoring device 30 on the first layer is connected to the transceiver 16 of the battery monitoring ECU 10 via connector 34, transmission path 22, and connector 18. The receiver 42 of each battery monitoring device 30 on the second to m-th layers is connected to the transmitter 44 of the battery monitoring device 30 on the previous layer via connector 34, corresponding transmission paths 24, 25, ..., and connector 36. The transmitter 44 of the battery monitoring device 30 on the m-th layer is connected to the transceiver 16 of the battery monitoring ECU 10 via connector 36, transmission path 26, and connector 20.

[0029] Receiver 42 receives differential signals from devices on the previous layer and recovers the superimposed signal from the differential signals. Here, when controller 48 is the controller 48 of the battery monitoring device 30 on the first layer, the device on the previous layer is the battery monitoring ECU 10, and when controller 48 is the controller 48 of the battery monitoring device 30 on any of the second to m-th layers, the device on the previous layer is the battery monitoring device 30. Here, when controller 48 is the controller 48 of the battery monitoring device 30 on the first layer, the superimposed signal is a first superimposed signal, and when controller 48 is the controller 48 of the battery monitoring device 30 on any of the second to m-th layers, the superimposed signal is a second superimposed signal generated by the battery monitoring device 30 on the previous layer.

[0030] The controller 48 extracts the clock of the superimposed signal received by the receiver 42 as a reference clock signal, and recovers and decodes the battery monitoring information, the battery monitoring results up to the previous layer, and the difference information of the second clock signal up to the battery monitoring device 30 up to the previous layer from the superimposed signal. When the controller 48 is the controller 48 of the battery monitoring device 30 on the first layer, the superimposed signal is the first superimposed signal generated by the host controller 14 of the battery monitoring ECU 10, and the superimposed signal does not include the difference information of the battery monitoring results up to the previous layer and the second clock signal up to the battery monitoring device 30 up to the previous layer.

[0031] The reference clock signal is obtained by recovering the clock signal before superposition from the received superposition signal. Therefore, in the battery monitoring device 30 on the first layer, the frequency of the reference clock signal is the same as the frequency of the first clock signal, and in the battery monitoring devices 30 on the second to m-th layers, the frequency of the reference clock signal is the same as the frequency of the second clock signal of the battery monitoring device 30 on the previous layer.

[0032] The controller 48 superimposes the battery monitoring information, the battery monitoring results up to the current layer, and the difference information of the second clock signal up to the current layer's battery monitoring device 30 onto the second clock signal to generate a second superimposed signal.

[0033] The second clock generator 50 generates a second clock signal as a reference for the operation of the battery monitoring device 30. The second clock generator 50 includes an LC oscillator, which is simpler than the crystal oscillator used in the first clock generator 12. Therefore, the second clock signal is a clock signal with lower accuracy than the first clock signal. Since the second clock generator 50 uses an LC oscillator, the oscillation frequency can be easily changed and corrected by altering the capacitance of the capacitor constituting the LC oscillator or the inductance constituting the inductor according to correction instructions from the controller 48.

[0034] Frequency monitor 53 monitors the second clock signal and reference clock signal generated by the second clock generator 50, and detects the frequency deviation between the second clock signal and the reference clock signal, i.e., the frequency difference. Controller 48 obtains this difference as the difference information of the second clock signal.

[0035] The battery monitor 54 uses a second clock signal to detect the battery status via AC impedance method. Note that the controller 48 can enable the battery monitor 54 to continuously monitor the battery status, and if a battery is being monitored in the battery monitoring information, the controller 48 can obtain the measurement results of the battery status detected by the battery monitor 54.

[0036] The transmitter 44 generates a differential signal based on the second superimposed signal and sends the differential signal to the device on the subsequent layer. Here, when the controller 48 is the controller 48 of the battery monitoring device 30 on any of the first to (m-1)th layers, the device on the subsequent layer is the battery monitoring device 30, and when the controller 48 is the controller 48 of the battery monitoring device 30 on the mth layer, the device on the subsequent layer is the battery monitoring ECU 10.

[0037] (Operation of Battery Monitoring System 100)

[0038] Figure 2 This is a flowchart of the process executed by the host controller 14 of the battery monitoring ECU 10. In step S10, the host controller 14 of the battery monitoring ECU 10 sends battery monitoring information to the battery monitoring device 30 on the first layer. Specifically, the host controller 14 of the battery monitoring ECU 10 generates a first superimposed signal by superimposing the battery monitoring information onto a first clock signal. The host controller 14 causes the transceiver 16 to generate a differential signal from the first superimposed signal and sends the differential signal to the battery monitoring device 30 on the first layer. The battery monitoring information includes correction instruction information indicating whether the frequency of the second clock signal of the battery monitoring device 30 should be corrected. Note that the first instruction for obtaining the battery status does not include the correction instruction for correcting the frequency of the second clock signal of the battery monitoring device 30.

[0039] In step S20, the host controller 14 of the battery monitoring ECU 10 receives battery monitoring results, including instructions for monitoring battery status, and difference information of the second clock signal of the battery monitoring device 30 (which is the last layer) from the battery monitoring device 30 at the m-th layer. This result is superimposed on the second superimposed signal. When the determination result in step S20 is true (T) (meaning the host controller 14 has received the second superimposed signal), the host controller 14 transfers the processing to step S30. Conversely, when the determination result in step S20 is false (F) (meaning the second superimposed signal has not yet been received), the host controller 14 repeats step S20 until the determination result is true (T), indicating that the second superimposed signal has been received.

[0040] In step S30, the host controller 14 recovers from the second superimposed signal the monitoring results of the battery status in the battery monitoring device 30 on each layer and the difference information of the deviation between the frequency of the second clock signal and the frequency of the reference clock signal in the battery monitoring device 30 on each layer.

[0041] In step S40, the host controller 14 calculates and obtains the frequency of the second clock signal in the battery monitoring device 30 on each layer by using the frequency of the first clock signal and the difference information between the frequency of the second clock signal in the battery monitoring device 30 on each layer and the frequency of the reference clock signal.

[0042] Steps S50 to S100 are cyclical, and the host controller 14 processes the battery monitoring device 30 on each layer. In step S60, the host controller 14 determines the relationship between the difference Δf between the frequencies of the first clock signal and the second clock signal and the magnitudes of two thresholds (first threshold TH1 and second threshold TH2). The second threshold TH2 is greater than the first threshold TH1. When the absolute value |Δf| of the frequency difference Δf is equal to or less than the first threshold TH1, the host controller 14 transfers the processing to step S70. When the absolute value |Δf| of the frequency difference Δf is greater than the first threshold TH1 and equal to or less than the second threshold TH2, the host controller 14 transfers the processing to step S80. When the absolute value |Δf| of the frequency difference Δf is greater than the second threshold TH2, the host controller 14 transfers the processing to step S90.

[0043] In step S70, the host controller 14 acquires the battery status monitoring result from the battery monitoring device 30 superimposed on the second superimposed signal as the battery status monitoring result. Afterwards, the process proceeds to step S100.

[0044] In step S80, the host controller 14 corrects the battery status monitoring result in the battery monitoring device 30 superimposed on the second superimposed signal by using the difference between the frequency of the first clock signal and the frequency of the second clock signal, and obtains the result as the battery status monitoring result. Afterwards, the process proceeds to step S100.

[0045] In step S90, the host controller 14 determines the frequency of the second clock signal to be corrected. Afterward, the process proceeds to step S100.

[0046] In step S110, the host controller 14 determines whether to monitor the battery in the next cycle. When the absolute value of the frequency difference Δf in at least one battery monitoring device of the battery monitoring device 30, |Δf|, is greater than the second threshold TH2, the host controller 14 can determine that the battery will be monitored in the next cycle. When the determination in step S110 is true (T) (meaning monitoring will be performed in the next cycle), the host controller 14 transfers the processing to step S10 and repeats the above process. Note that in the next cycle after returning from step S110 and in subsequent steps S10, the battery monitoring information includes a correction instruction to correct the frequency of the second clock signal of the battery monitoring device 30. Therefore, the frequency of the second clock signal is corrected in the battery monitoring device 30 that has received the correction instruction. When the determination in step S110 is false (F) (meaning monitoring will not be performed in the next cycle), the host controller 14 ends the processing.

[0047] Figure 3 This is a flowchart of the operations performed by the controller 48 of the battery monitoring device 30. In step S200, the controller 48 receives a superimposed signal from the device on the previous layer via the receiver 42. Here, when the battery monitoring device 30 is the battery monitoring device on the first layer, the device on the previous layer is the battery monitoring ECU 10, and when the battery monitoring device 30 is the battery monitoring device on any of the second to m-th layers, the device on the previous layer is the battery monitoring device 30. When the battery monitoring device 30 is the battery monitoring device on the first layer, the superimposed signal is a first superimposed signal, and when the battery monitoring device 30 is the battery monitoring device on any of the second to m-th layers, the superimposed signal is a second superimposed signal.

[0048] In step S210, the controller 48 recovers and decodes the superimposed signal to generate a reference clock signal. In the battery monitoring device 30 on the first layer, the superimposed signal is a first superimposed signal. Therefore, the controller 48 generates a reference clock signal with the same frequency as the first clock signal and acquires battery monitoring information. In the battery monitoring device 30 on any of the second to m-th layers, the superimposed signal is a second superimposed signal. Therefore, the controller 48 generates a reference clock signal with the same frequency as the second clock signal on the previous layer and acquires battery monitoring information, monitoring results of the battery state on each layer up to the previous layer (also referred to as "battery monitoring results"), and information indicating the difference between the frequency of the second clock signal and the frequency of the reference clock signal on each layer up to the previous layer.

[0049] In step S220, the controller 48 determines whether the battery monitoring information contains a correction instruction to correct the frequency of the second clock signal. When the determination in step S220 is true (T) (meaning that the battery monitoring information includes a correction instruction to correct the frequency of the second clock signal), the controller 48 transfers the processing to step S230. On the other hand, when the determination in step S220 is false (F) (meaning that the battery monitoring information does not include a correction instruction to correct the frequency of the second clock signal), the controller 48 transfers the processing to step S240.

[0050] In step S230, the controller 48 instructs the second clock generator 50 to correct the frequency of the second clock signal. As described above, the second clock generator 50 changes and corrects the oscillation frequency by changing the capacitance of the capacitor constituting the LC oscillator or the inductance constituting the inductor.

[0051] In step S240, the controller 48 obtains the difference between the frequency of the reference clock signal and the frequency of the second clock signal generated by the second clock generator 50 from the frequency monitor 53.

[0052] In step S250, the controller 48 obtains the state of the battery to be monitored from the battery monitor 54, which is detected by the battery monitor 54 using a second clock signal.

[0053] In step S260, the controller 48 generates a second superimposed signal by superimposing battery monitoring information, battery monitoring results on each layer up to the current layer, and information indicating the difference between the frequency of the reference clock signal and the frequency of the second clock signal on each layer up to the current layer onto the second clock signal.

[0054] In step S270, the controller 48 causes the transmitter 44 to generate a differential signal from the second superimposed signal and sends the differential signal to the device on the subsequent layer. As described above, when the controller 48 is the battery monitoring device 30 on the m-th layer as the last layer, the device on the subsequent layer is the battery monitoring ECU 10, and when the controller 48 is the battery monitoring device 30 on a layer other than the m-th layer, the device on the subsequent layer is the battery monitoring device 30.

[0055] Figure 4 This is an explanatory diagram of the first superimposed signal sent by the battery monitoring ECU 10 and the second superimposed signal sent and received by the battery monitoring device 30. The battery monitoring ECU 10 sends a first superimposed signal with frequency f0. The receiver 42 of the battery monitoring device 30 on the first layer receives the first superimposed signal with frequency f0, and the transmitter 44 of the battery monitoring device 30 on the first layer sends a second superimposed signal with frequency f1. The receiver 42 of the battery monitoring device 30 on the second layer receives the second superimposed signal with frequency f1, and the transmitter 44 of the battery monitoring device 30 on the second layer sends a second superimposed signal with frequency f2. Similarly, the receiver 42 of the battery monitoring device 30 on the x-th layer receives a second superimposed signal with frequency f(x-1), and the transmitter 44 of the battery monitoring device 30 on the x-th layer sends a second superimposed signal with frequency fx.

[0056] In the battery monitoring device 30 on the first layer, frequencies f1-f0 are the difference Δf1 between the frequency of the reference clock signal (first clock signal) and the frequency of the second clock signal on the first layer. In the battery monitoring device 30 on the second layer, frequencies f2-f1 are the difference Δf2 between the frequency of the reference clock signal (second clock signal) and the frequency of the second clock signal on the second layer. Similarly, in the battery monitoring device 30 on the xth layer, frequency fx-f(x-1) is the difference Δfx between the frequency of the reference clock signal (second clock signal) and the frequency of the second clock signal on the xth layer. In the battery monitoring device 30 on the xth layer, the controller 48 adds the differences Δf1 to Δfx sequentially up to the xth layer when generating the second superimposed signal. That is, the frequency differences Δf1 to Δfm in the battery monitoring devices 30 on each layer are added to the second superimposed signal.

[0057] The battery monitoring ECU 10 calculates the frequency of the second clock signal from the battery monitoring device 30 on the first layer sequentially by using the frequency information of the first clock signal and the frequency differences Δf1 to Δfm in the battery monitoring devices 30 on each layer. That is, the frequency f1 of the second clock of the battery monitoring device 30 on the first layer is f0 + Δf1, and the frequency f2 of the second clock of the battery monitoring device 30 on the second layer is f1 + Δf2 = f0 + Δf1 + Δf2. Similarly, the host controller 14 can calculate the frequencies f3 to fm of the second clock of the battery monitoring devices 30 on the third to m-th layers. The host controller 14 can obtain the absolute error of the frequency of the second clock signal on each layer relative to the frequency f0 of the first clock signal by comparing the frequency f0 of the first clock signal with the frequencies f1 to fm of the second clock signal in the monitoring devices 30 on each layer. Then, the host controller 14 can determine how much the frequency of the battery monitoring device 30 on which layer needs to be corrected.

[0058] As described above, in this embodiment, the controller 48 of the battery monitoring device 30 outputs the monitoring results of the frequency of the second clock signal to subsequent layers. As a result, the host controller 14 of the battery monitoring ECU 10 can calculate the frequency of the second clock signal on each layer by using the monitoring results of the frequency of the second clock signal on each layer, and determine which second clock signal of the battery monitoring device 30 will be corrected.

[0059] In this embodiment, the host controller 14 of the battery monitoring ECU 10 sends a calibration command to the battery monitoring device 30. In each layer of the battery monitoring device 30, the controller 48 extracts the difference from the first layer to the previous layer contained in the superimposed signal from the previous layer, and, taking the difference into account, obtains the frequency difference between the frequency of the first clock signal received from the battery monitoring ECU by the first layer and the frequency of the second clock signal on the current layer. When the frequency difference is greater than a predetermined threshold, the controller 48 on the current layer can cause the second clock generator 50 to correct the frequency of the second clock signal according to the frequency deviation. In the next cycle, the number of battery monitoring devices 30 in which the second clock signal needs to be corrected can be reduced.

[0060] In this embodiment, the host controller 14 can calculate and obtain the absolute deviation between the frequency of the second clock signal and the frequency of the first clock signal by using the difference information on each layer of the battery monitoring device 30, that is, the frequency difference between the frequency of the second clock signal and the frequency of the first clock signal.

[0061] In this embodiment, the host controller 14 can obtain the absolute deviation between the frequency of the second clock signal and the frequency of the first clock signal, that is, the frequency difference between the frequency of the second clock signal and the frequency of the first clock signal, as well as the state of the battery.

[0062] In this embodiment, when the difference between the frequency of the second clock signal and the frequency of the first clock signal in the battery monitoring device 30 is greater than the first threshold TH1 and equal to or less than the second threshold TH2, the host controller 14 can use the difference between the frequencies of the first clock signal and the second clock signal to correct and obtain the state of the battery.

[0063] In this embodiment, when the frequency monitor 53 on the current layer determines that the relative deviation between the frequency of the second clock signal and the frequency of the reference clock signal extracted from the superimposed signal received from the battery monitoring device 30 on the previous layer is greater than a predetermined threshold, the controller 48 on the current layer can cause the second clock generator to correct the frequency of the second clock signal according to the frequency deviation.

[0064] (Second Embodiment)

[0065] Figure 5 This is a schematic configuration diagram of a battery monitoring system 101 according to a second embodiment. In the battery monitoring system 101 according to the second embodiment, the battery monitoring ECU 11 does not include connector 20, and transceiver 16 is connected to transmission path 22 via connector 18. Furthermore, the battery monitoring device 32 includes receiver 43 instead of receiver 42 and transmitter 44. The battery monitoring system 101 differs from the battery monitoring system 100 according to the first embodiment in that the battery monitoring ECU 10 and the plurality of battery monitoring devices 32 are daisy-chained. The battery monitoring device 32 includes two connectors 34 and 36, and the terminal device 28 is connected to connector 36 of the battery monitoring device 32 on the m-th layer, which is the last layer. Note that, depending on the configuration of transceiver 43, the terminal device 28 does not need to be connected to connector 36. In the first embodiment, connector 34 is used as an input unit, and connector 36 is used as an output unit. However, in the second embodiment, connector 34 is used as an input unit, and connector 36 is used as an output unit. Connector 36 can be switched to be used as an input unit, and connector 34 can be switched to be used as an output unit. The second superimposed signal from the m-th layer, which is the last layer, is sent in reverse from the battery monitoring device 32 on the m-th layer to the battery monitoring device 32 on the first layer.

[0066] In the second embodiment, as in the first embodiment, the host controller 14 can obtain the frequency error of the second clock signal on each layer by comparing the frequency f0 of the first clock signal with the frequencies f1 to fm of the second clock signals in the battery monitoring devices 30 on each layer. The host controller 14 can then determine how much the frequency of the battery monitoring devices 30 on which layer needs to be corrected.

[0067] (Third Embodiment)

[0068] Figure 6 This is a schematic configuration diagram of a battery monitoring system 102 according to a third embodiment. In the battery monitoring system 102 according to the third embodiment, a plurality of battery monitoring devices 33 are connected to a battery monitoring ECU 11 via a multi-point connection. The transceiver 16 of the battery monitoring ECU 11 does not include connector 20 and is connected to the transmission path 27 via connector 18. Each of the battery monitoring devices 33 does not include connector 36; receiver 42 and transmitter 44 are connected to a connector 34, and connector 34 is connected to the transmission path 27.

[0069] In the battery monitoring system 102 according to the third embodiment, signals from the battery monitoring ECU 11 are transmitted via connector 18 and transmission path 27 to the receiver 42 of the battery monitoring device 33 on the first layer. Signals output from the battery monitoring device 33 on the first layer are transmitted from transmitter 44 to the receiver 42 of the battery monitoring device 33 on the second layer, which is the subsequent layer, via connector 34 and transmission path 27. Similarly, signals output from the battery monitoring device 33 on the xth layer are transmitted from transmitter 44 to the receiver 42 of the battery monitoring device 33 on the (x+1)th layer, which is the subsequent layer, via connector 34 and transmission path 27. Signals output from the battery monitoring device 33 on the mth layer, which is the last layer, are transmitted from transmitter 44 to the transceiver 16 of the battery monitoring ECU 11 via connector 34 and transmission path 27. In this way, each battery monitoring device 30 sequentially transmits superimposed signals using the same transmission path 27. Regarding transmission, each battery monitoring device 33 sequentially transmits superimposed signals to subsequent layers by using a token to utilize the right to use the transmission path 27.

[0070] In the third embodiment, the operation is the same as in the first embodiment, and similar to the first embodiment, the host controller 14 can obtain the absolute error of the frequency of the second clock signal in the battery monitoring device 33 on each layer relative to the frequency of the first clock signal by comparing the frequency f0 of the first clock signal with the frequencies f1 to fm of the second clock signal in the battery monitoring device 33 on each layer. The host controller 14 can then determine how much the frequency of the battery monitoring device 33 on which layer needs to be corrected.

[0071] As can be seen from the first to the third embodiments, the connection between the battery monitoring ECU and multiple battery monitoring devices can be in various forms, such as ring connection, daisy chain connection, multi-point connection, etc.

[0072] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the spirit of this disclosure. For example, in order to solve some or all of the above problems or achieve some or all of the above effects, the technical features in each embodiment corresponding to the technical features of the form described in the summary of the invention can be appropriately replaced or combined. Technical features that are not described as necessary herein can be omitted as appropriate.

Claims

1. A battery monitoring system that monitors states of a plurality of batteries, the battery monitoring system comprising: a battery monitoring ECU; and a plurality of battery monitoring devices, wherein the battery monitoring ECU and the plurality of battery monitoring devices are connected to each other in any connection form of a ring connection, a daisy chain connection, or a multi-point connection, the battery monitoring ECU includes a first clock generator configured to generate a first clock signal, and a transceiver configured to output a superimposed signal to at least one of the plurality of battery monitoring devices, and to receive a monitoring result of states of the plurality of batteries, wherein battery monitoring information is superimposed on the first clock signal in the superimposed signal, and each of the plurality of battery monitoring devices includes a receiver configured to receive a superimposed signal from a previous layer, a second clock generator configured to generate a second clock signal that serves as a reference for operation of a corresponding battery monitoring device, a controller configured to extract a clock from the superimposed signal of the previous layer as a reference clock signal, and to restore the battery monitoring information, a battery monitor configured to monitor states of one or more batteries of the corresponding battery monitoring device by using the second clock signal and the battery monitoring information, a frequency monitor configured to monitor a difference between a frequency of the reference clock signal and a frequency of the second clock signal, and a transmitter configured to output the battery monitoring information, a monitoring result up to a layer on the current layer, and difference information indicating a difference up to the layer on the current layer, to a subsequent layer.

2. The battery monitoring system according to claim 1, wherein the battery monitoring ECU includes a host controller configured to calculate a frequency difference between a frequency of the second clock signal and a frequency of the first clock signal by using difference information on each layer of the plurality of battery monitoring devices.

3. The battery monitoring system according to claim 2, wherein the host controller acquires the frequency difference between the frequency of the second clock signal and the frequency of the first clock signal and states of the one or more batteries.

4. The battery monitoring system according to claim 2 or 3, wherein when a difference between the frequency of the second clock signal and the frequency of the first clock signal in the corresponding battery monitoring device is greater than a first threshold value (TH1) and equal to or smaller than a second threshold value (TH2), the host controller corrects and acquires the states of the one or more batteries of the corresponding battery monitoring device by using the difference between the frequency of the first clock signal and the frequency of the second clock signal.

5. The battery monitoring system according to any one of claims 1 to 3, wherein When the frequency monitor on the current tier determines that the frequency of the second clock signal has a relative deviation from the frequency of the reference clock signal extracted from the superimposed signal received from the battery monitor device on the previous tier that is greater than a predetermined threshold, the controller on the current tier causes the second clock generator to correct the frequency of the second clock signal according to the deviation in frequency.

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