Battery monitoring device, battery monitoring system and method for monitoring battery module

Abstract

The invention relates to a battery monitoring apparatus, a battery monitoring system and a method for monitoring a battery module. A battery monitoring device includes a monitoring circuit, a communication port, and a control circuit. The communication port receives sensing commands from the battery management unit through a set of other battery monitoring devices. The control circuit starts timing of a preset time delay when the control circuit executes the sensing command, and controls the monitoring circuit to sense a state of the first battery module when the preset time delay expires, such that the monitoring circuit senses the state of the first battery module at a time point synchronized with a sensing time point of the other battery monitoring device. The control circuit controls the communication port to transmit information including a state of the first battery module to the battery management unit through another battery monitoring device.

Description

Technical Field

[0001] The present invention relates to the field of battery monitoring, and more particularly to battery monitoring devices, battery monitoring systems, and methods for monitoring battery modules. Background Art

[0002] Figure 1 A block diagram of a conventional battery monitoring system 100 is shown. The battery monitoring system 100 includes a plurality of battery modules 102_1 to 102_n (n = 2, 3, 4,...), a plurality of Analog Front Ends (AFEs) 104_1 to 104_n, a plurality of isolators 106, and a Battery Management Unit (BMU) 108. As Figure 1 shown, each of the AFEs 104_1 to 104_n is coupled to a corresponding one of the battery modules 102_1 to 102_n and is configured to monitor the state of the corresponding battery module, such as voltage. Each pair of adjacent analog front ends among the AFEs 104_1 to 104_n are coupled to each other through the isolator 106. The AFE 104_1 is coupled to the BMU 108, and the AFEs 104_2 to 104_n are coupled to the BMU 108 through the AFE 104_1.

[0003] A daisy-chain communication link can be established between the BMU 108 and the AFEs 104_1 to 104_n. Through the daisy-chain communication link, the BMU 108 can control the AFEs 104_1 to 104_n to monitor the states of the battery modules 102_1 to 102_n and obtain the state information of the battery modules 102_1 to 102_n. Specifically, the BMU 108 can send a status monitoring command SMC to the AFEs 104_1 to 104_n through the daisy-chain communication link, and the status monitoring command SMC is set to instruct the AFEs 104_1 to 104_n to monitor the states of the battery modules. In response to the status monitoring command SMC, the AFEs 104_1 to 104_n can obtain the state information of the battery modules and send the state information to the BMU 108 through the daisy-chain communication link.

[0004] In a daisy-chain communication link, a status monitoring command (SMC) is sequentially relayed to AFEs 104_1 to 104_n. Specifically, the BMU 108 sends the status monitoring command SMC to the AFE 104_1. The status monitoring command SMC is forwarded from the AFE 104_1 to the AFE 104_2, and the AFE 104_2 further forwards the command to the AFE 104_3, and so on, sequentially to the AFE 104_n. Each AFE monitors the status of the corresponding battery module in response to the status monitoring command SMC, and sends the obtained status information to the BMU 108 through the daisy-chain communication link. For example, the AFE 104_1 sends its status information to the BMU 108, the AFE 104_2 sends its status information to the AFE 104_1, and the AFE 104_1 sends the status information from the AFE 104_2 to the BMU 108, and so on.

[0005] However, there is a propagation delay when each AFE forwards the status monitoring command SMC. Therefore, the acquisition times of the status information of the battery modules obtained by each of the AFEs 104_1 to 104_n are different, which may result in inaccuracies when using the status information of the battery modules 102_1 to 102_n to determine battery states such as the state of charge (SOC) and the state of health (SOH). Summary of the Invention

[0006] In an embodiment, a battery monitoring device includes a monitoring circuit, a communication port, and a control circuit coupled to the monitoring circuit and the communication port. The monitoring circuit can sense the status of a first battery module. The communication port can receive a sensing command provided by a battery management unit through a serial communication link. The serial communication link includes a group of battery monitoring devices including the battery monitoring device. The battery monitoring device is coupled to a group of battery modules including the first battery module. Each device in the battery monitoring device can sense the status of the corresponding battery module in the battery modules at a sensing time point. The control circuit can start timing a preset time delay when the control circuit starts to execute the sensing command. The control circuit can also control the monitoring circuit to sense the status of the first battery module when the preset time delay expires, such that the monitoring circuit senses the status of the first battery module at a time point synchronized with the sensing time point. Additionally, the control circuit can control the communication port to send information including the status of the first battery module to the battery management unit through the serial communication link.

[0007] In addition, in an embodiment, a battery monitoring system includes a serial communication link that includes a plurality of battery monitoring devices operable to sense the states of a plurality of battery modules at a sensing time point. The plurality of battery monitoring devices includes a first battery monitoring device that includes a monitoring circuit, a communication port, and a control circuit. The monitoring circuit is operable to sense the state of a first battery module among the plurality of battery modules. The communication port is operable to receive a first sensing command from a battery management unit via the serial communication link. The control circuit is coupled to the monitoring circuit and the communication port and is operable to execute the first sensing command, operable to start timing of a preset time delay when the control circuit starts to execute the first sensing command, and operable to control the monitoring circuit to sense the state of the first battery module when the preset time delay expires, such that the monitoring circuit senses the state of the first battery module at a time point synchronized with the sensing time point. The control circuit is further operable to control the communication port to send information including the sensed state of the first battery module to the battery management unit via the serial communication link.

[0008] In addition, in an embodiment, a method for monitoring a plurality of battery modules includes: receiving, by a first battery monitoring device among the plurality of battery monitoring devices, a first sensing command sent by a battery management unit via a serial communication link, where the serial communication link includes the plurality of battery monitoring devices; starting timing of a preset time delay when the first battery monitoring device starts to execute the first sensing command; sensing, by the plurality of battery monitoring devices, the states of the plurality of battery modules at a sensing time point, where the first battery monitoring device senses the state of a first battery module among the plurality of battery modules when the preset time delay expires, such that the first battery monitoring device senses the state of the first battery module at a time point synchronized with the sensing time point; and sending, via the serial communication link, information including the sensed state of the first battery module to the battery management unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] As the following detailed description proceeds and with reference to the drawings, the features and advantages of embodiments of the claimed subject matter will become apparent, where like reference numerals depict like components, and in the drawings:

[0010] Figure 1 A block diagram showing some of the elements and components in a conventional battery monitoring system is shown.

[0011] Figure 2A An example circuit diagram of a battery monitoring system (showing some of the elements and components in the system) in an embodiment of the present invention is shown.

[0012] Figure 2BShows an example circuit diagram of a battery monitoring system (showing some of the elements and components in the system) in an embodiment of the present invention.

[0013] Figure 3 Shows an example diagram of the process of sending sensing commands executed by multiple battery monitoring devices in an embodiment of the present invention.

[0014] Figure 4A Shows an example diagram of the process of sending sensing commands executed by multiple battery monitoring devices in an embodiment of the present invention.

[0015] Figure 4B Shows an example diagram of the process of sending sensing commands executed by multiple battery monitoring devices in an embodiment of the present invention.

[0016] Figure 5 Shows an example diagram of the monitoring process of multiple battery cells executed by a battery monitoring device in an embodiment of the present invention.

[0017] Figure 6 Shows an example diagram of the monitoring process of multiple battery cells executed by a battery monitoring device in an embodiment of the present invention.

[0018] Figure 7 Shows an example flowchart of a method for monitoring multiple battery modules in an embodiment of the present invention.

[0019] Figure 8 Shows an example diagram (prior art) for explaining the fast Fourier transform.

[0020] Figure 9 Shows an example diagram in which a set of calculated values of the internal resistance of a battery module is transformed into an impedance spectrum of the battery module in an embodiment of the present invention. Detailed Embodiments

[0021] Now, reference will be made in detail to the embodiments of the present invention. Although the present invention will be described in conjunction with these embodiments, it should be understood that they are not intended to limit the present invention to these embodiments. On the contrary, the present invention is intended to cover alternatives, modifications, and equivalents that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0022] In addition, in the following detailed description of the present invention, many specific details are set forth to provide a thorough understanding of the present invention. However, those of ordinary skill in the art will recognize that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

[0023] Embodiments of the present invention provide a battery monitoring device, a battery monitoring system, and a method for monitoring a battery pack including a plurality of battery modules. The battery monitoring system may include a serial communication link including a plurality of battery monitoring devices, and may further include a battery management unit (BMU) communicating with each battery monitoring device via the serial communication link. Each battery monitoring device may receive a sensing command from the BMU via the serial communication link, set a corresponding time delay when receiving or executing the sensing command, and start sensing the state of the corresponding battery module when the corresponding time delay expires. Thus, the battery monitoring devices in the serial communication link may sense the states of the battery modules synchronously, thereby improving the accuracy of determining the states of the battery modules such as SOC and / or SOH.

[0024] Figure 2A FIG. 4 shows an example circuit diagram of a battery monitoring system 200A (showing some of the elements and components in the system) in an embodiment of the present invention. The battery monitoring system 200A includes a plurality of battery monitoring devices 204_1 to 204_n (n = 2, 3, 4,...). Each of the battery monitoring devices 204_1 to 204_n includes a corresponding monitoring circuit 212, a corresponding communication port 214, and a corresponding control circuit 216. As Figure 2A shown, the battery monitoring system 200A may further include a plurality of battery modules 202_1 to 202_n, a plurality of isolators 206, a battery junction box (BJB) 210, and a battery management unit (BMU) 208.

[0025] In an embodiment, each of the battery monitoring devices 204_1 to 204_n may monitor the state (e.g., voltage, temperature, and / or abnormal conditions, etc.) of the corresponding battery module. Each of the battery monitoring devices 204_1 to 204_n may include, but is not limited to, an analog front end (AFE). Each of the battery modules 202_1 to 202_n may include a plurality of battery cells.

[0026] In Figure 2A the embodiment, each of the battery modules 202_1 to 202_n includes a plurality of battery cells coupled in series. However, the present invention is not limited thereto. In another embodiment, each of the battery modules 202_1 to 202_n includes a plurality of battery cells coupled in parallel.

[0027] In an embodiment, the battery cells of each of the battery modules 202_1 to 202_n include rechargeable battery cells such as lithium-ion (Li-ion) battery cells. In other embodiments, the battery cells in the battery modules 202_1 to 202_n include other types of rechargeable battery cells, such as lead-acid battery cells, nickel-cadmium (NiCd) battery cells, nickel-metal hydride (NiMH) battery cells, sodium batteries, or supercapacitors. The battery modules 202_1 to 202_n can be used in high-power application environments, such as electric vehicles (EVs), energy walls, etc. As Figure 2A shown, the battery modules 202_1 to 202_n can be coupled to a load 220 and supply power to the load 220.

[0028] As Figure 2A shown, the battery modules 202_1 to 202_n are coupled in series. The battery monitoring devices 204_1 to 204_n are coupled in a daisy-chain communication link. Each pair of adjacent devices among the battery monitoring devices 204_1 to 204_n is coupled through a corresponding isolator 206. For illustration, taking the j-th (j = 2, ……, n - 1) battery monitoring device 204_j among the battery monitoring devices 204_1 to 204_n as an example, the communication port 214 of the battery monitoring device 204_j can include a first communication port and a second communication port. The first communication port of the battery monitoring device 204_j can be coupled to the battery monitoring device 204_(j - 1) via the isolator 206, and the second communication port of the battery monitoring device 204_j can be coupled to the battery monitoring device 204_(j + 1) via another isolator 206. Additionally, the communication port 214 of the battery monitoring device 204_1 can also include a first communication port and a second communication port. The first communication port of the battery monitoring device 204_1 can be coupled to the BJB 210 via the isolator 206, and the second communication port of the battery monitoring device 204_1 can be coupled to the battery monitoring device 204_2 via another isolator 206.

[0029] In an embodiment, the monitoring circuit 212 in each of the battery monitoring devices 204_1 to 204_n is coupled to the corresponding battery module among the battery modules 202_1 to 202_n and is configured to monitor the state of its corresponding battery module. For illustration, taking the k-th (k = 1, 2, ……, n) battery monitoring device 204_k as an example, the monitoring circuit 212 in the battery monitoring device 204_k is coupled to the battery module 202_k and is configured to monitor the state (e.g., voltage and / or temperature) of the battery module 202_k.

[0030] As Figure 2AAs shown, the BMU 208 includes a controller 208_2 (e.g., a microcontroller unit (MCU), an electronic control unit (ECU), etc.) and a bridge integrated circuit (abbreviation: bridge IC) 208_1. The BJB 210 may include a battery junction box analog front end (abbreviation: BJB_AFE) 210_1, two isolators 206, and a resistor component R0. The controller 208_2 is coupled to the bridge IC 208_1. The bridge IC 208_1 is coupled to the BJB_AFE 210_1 via the first isolator 206 in the BJB 210. The BJB_AFE 210_1 is coupled to the battery monitoring device 204_1 via the second isolator 206 in the BJB 210 and also via another isolator 206 between the BJB 210 and the battery monitoring device 204_1.

[0031] In an embodiment, a serial communication link may be established between the BMU 208 and the battery monitoring devices 204_1 to 204_n. In Figure 2A an example, the serial communication link 211 includes the battery monitoring devices 204_1 to 204_n, the BJB_AFE 210_1, and the BMU 208. The BMU 208 can communicate with the battery monitoring devices 204_1 to 204_n and control the battery monitoring devices 204_1 to 204_n to monitor the states of the battery modules 202_1 to 202_n through preset commands sent via the serial communication link. In an embodiment, the multiple devices in the serial communication link are connected in series, and information is relayed sequentially from one device to the adjacent device among the multiple devices. Such a serial communication link may also be referred to as a daisy chain communication link. Additionally, the serial communication link may include a linear serial communication link 211 (as Figure 2A shown) or a ring serial communication link 213 (as Figure 2B shown). In an embodiment, the linear serial communication link mentioned herein refers to a communication link in which multiple devices in the link are connected in series without forming a ring, and the ring serial communication link refers to a communication link in which multiple devices in the link are connected in series and form a ring.

[0032] As Figure 2AAs shown, the BMU 208 can communicate with battery monitoring devices 204_1 to 204_n via a linear serial communication link 211, and can send a sensing command SC to the battery monitoring devices 204_1 to 204_n via the linear serial communication link 211 to instruct the battery monitoring devices 204_1 to 204_n to monitor the states of battery modules 202_1 to 202_n. The controller 208_2 can generate the sensing command SC and send the sensing command SC to the BJB 210 and the battery monitoring devices 204_1 to 204_n via the linear serial communication link 211 using the bridge IC 208_1. The sensing command SC can be sequentially relayed to the BJB 210 and the battery monitoring devices 204_1 to 204_n, for example, from the first device to the next adjacent device (the second device), from the second device to the next adjacent device (the third device), and so on, like a daisy-chain communication link. In response to the sensing command SC, the battery monitoring devices 204_1 to 204_n can monitor the states of their corresponding battery modules and sequentially send the state information of their corresponding battery modules to the controller 208_2 via the linear serial communication link 211 as described above. In an embodiment, the communication port 214 of each of the battery monitoring devices 204_1 to 204_n is coupled to the linear serial communication link 211 and receives the sensing command SC generated and / or provided by the BMU 208 via the linear serial communication link 211.

[0033] In an embodiment, the BMU 208 can control the BJB 210 to monitor the current I flowing through the battery modules 202_1 to 202_n via the linear serial communication link 211 BAT . For example, in response to the sensing command SC, the BJB_AFE 210_1 of the BJB 210 can monitor the current I of the battery modules 202_1 to 202_n via the resistor component R0 BAT , and send the information of the current I of the battery modules 202_1 to 202_n BAT to the controller 208_2 via the linear serial communication link 211. Additionally, the BJB_AFE 210_1 can receive the voltage information and / or other state information of the battery modules 202_1 to 202_n and forward this information to the BMU 208. The BJB_AFE 210_1 can also be referred to as the battery monitoring device 210_1.

[0034] In an embodiment, isolator 206 is used to transmit and receive signals, such as command signals provided by controller 208_2 and status information signals obtained by battery monitoring devices 204_1 to 204_n monitoring battery modules 202_1 to 202_n. More specifically, isolator 206 may allow the alternating current (AC) component of the command signal to pass through and may block the direct current (DC) component of the command signal. Thus, although battery monitoring devices 204_1 to 204_n operate with different reference grounds, isolator 206 may allow adjacent-coupled battery monitoring devices to communicate with each other using the AC component of the command signal while isolating the DC components of the command signals from both sides. In an embodiment, each isolator in isolator 206 includes a capacitor circuit, a converter, and the like.

[0035] Figure 2B FIG. 4 shows a circuit diagram example of a battery monitoring system 200B (showing some of the elements and components in the system) in another embodiment of the present invention. Battery monitoring system 200B is similar to battery monitoring system 200A, except that the bridge IC 208_1 in battery monitoring system 200B is coupled to battery monitoring device 204_n through isolator 206 to form a loop. Thus, as Figure 2B shown, a loop serial communication link 213 is established among BMU 208, BJB 210, and battery monitoring devices 204_1 to 204_n.

[0036] As Figure 2B shown, information and / or commands may flow sequentially through loop serial communication link 213 in a clockwise direction or in a counterclockwise direction (from one device to an adjacent device as described above). In an embodiment, loop serial communication link 213 includes an uplink and a downlink. Herein, the term "uplink" is optionally assigned to the counterclockwise direction, and the term "downlink" is optionally assigned to the clockwise direction. Thus, when information and / or commands are set to flow through loop serial communication link 213 in a counterclockwise direction, the information and / or commands are transmitted through the uplink of loop serial communication link 213; and when information and / or commands are set to flow through loop serial communication link 213 in a clockwise direction, the information and / or commands are transmitted through the downlink of loop serial communication link 213.

[0037] In an embodiment, the sensing command SC generated by the controller 208_2 can be sent in two different (opposite) directions in the ring serial communication link 213: that is, the same command is sent in both the uplink direction and the downlink direction. For example, the sensing command SC is represented as an uplink sensing command SC1 and a downlink sensing command SC2. The sensing command SC (uplink sensing command SC1) is sent through the uplink of the ring serial communication link 213. The sensing command SC (downlink sensing command SC2) is also sent through the downlink of the ring serial communication link 213. Specifically, the sensing command SC1 of the uplink is sequentially sent in the order of the bridge IC 208_1, the BJB 210, and the battery monitoring devices 204_1 to 204_n (such as in a daisy chain communication manner). The sensing command SC2 of the downlink is sequentially sent in the order of the bridge IC 208_1, the battery monitoring devices 204_n to 204_1, and the BJB 210 (such as in a daisy chain communication manner).

[0038] In another embodiment, the sensing command SC includes a different first sensing command (e.g., uplink sensing command) SC1 and a second sensing command (e.g., downlink sensing command) SC2. The first sensing command SC1 can be sent through the uplink of the ring serial communication link 213, and the second sensing command SC2 can be sent through the downlink of the ring serial communication link 213. The first sensing command SC1 and the second sensing command SC2 can be set according to the number of devices in the uplink and the number of devices in the downlink, and according to the propagation delay of each device in the ring serial communication link 213.

[0039] Therefore, in an embodiment, the sensing command SC can be sent in parallel through the uplink and the downlink of the ring serial communication link 213. More specifically, the battery monitoring system 200B can perform the first operation and the second operation in parallel. In the first operation, the bridge IC 208_1 can send the uplink sensing command SC1 to the first group of devices among the BJB 210 and the battery monitoring devices 204_1 to 204_n through the uplink. In the second operation, the bridge IC 208_1 can send the downlink sensing command SC2 to the second group of devices (e.g., the remaining devices not in the first group of devices) among the battery monitoring devices 204_1 to 204_n through the downlink. Therefore, the total propagation delay for the sensing command SC to reach all the battery monitoring devices 204_1 to 204_n can be reduced, and thus the time for determining the battery state such as SOC and / or SOH can be reduced.

[0040] Figure 3 An example diagram showing the process of sending the sensing command SC in the battery monitoring devices 204_1 to 204_n in an embodiment of the present invention. Refer toFigure 2A Description Figure 3 As Figure 3 shown, at time point T_A, the bridge IC 208_1 sends a sensing command SC to the BJB_AFE 210_1 via the linear serial communication link 211. After time point T_A, the sensing command SC is relayed in sequence (such as in a daisy-chain communication manner) in the order of BJB_AFE 210_1, battery monitoring device 204_1, battery monitoring device 204_2, ……, and battery monitoring device 204_(n - 1). In an embodiment, each of the battery monitoring devices 210_1 and 204_1 to 204_(n - 1) has a propagation delay T_PD when forwarding the sensing command SC, for example, the propagation delay from the moment when the battery monitoring device receives the sensing command SC to the moment when the device sends the sensing command SC. At time point T_B, the sensing command SC is sent to the last battery monitoring device 204_n.

[0041] As Figure 3 shown, the start time point of each propagation delay T_PD can be represented as the moment when the corresponding battery monitoring device receives (or executes) the sensing command SC, and the end time point of the propagation delay T_PD can be represented as the moment when the next battery monitoring device adjacent to and coupled to the corresponding battery monitoring device receives (or executes) the sensing command SC. In an embodiment, the propagation delays T_PD of the battery monitoring devices 210_1 and 204_1 to 204_(n - 1) are the same or approximately the same; however, as can be seen from the further discussion below, the present invention is not limited thereto.

[0042] Figure 4A An example diagram showing the process of sending sensing commands SC (uplink sensing command SC1 and downlink sensing command SC2) in two directions in the battery monitoring devices 204_1 to 204_n in another embodiment of the present invention is shown. Referring to Figure 2B Description Figure 4A As Figure 4A shown, at time point T_C, the bridge IC 208_1 sends the uplink sensing command SC1 to the BJB_AFE 210_1 and the downlink sensing command SC2 to the battery monitoring device 204_n in the clockwise and counterclockwise directions respectively via the ring serial communication link 213. After time point T_C, in the counterclockwise direction of the ring serial communication link 213, the uplink sensing command SC1 is sent in a relayed manner in the order of BJB_AFE 210_1 to battery monitoring devices 204_1, 204_2, ……, 204_p (1 < p < n) (such as in a daisy-chain communication manner); that is, the uplink sensing command SC1 is sent to the first group of devices mentioned above via the uplink of the ring serial communication link 213 (seeFigure 2B The discussion). Similarly, in the clockwise direction of the ring serial communication link 213, the downlink sensing command SC2 is sequentially transmitted in a relay manner in the order of the battery monitoring devices 204_n, 204_(n - 1), ……, 204_(p + 1) (such as in a daisy-chain communication manner); that is, the downlink sensing command SC2 is sent to the second group of devices mentioned above through the downlink of the ring serial communication link 213 (see Figure 2B ). At time point T_D, the uplink sensing command SC1 is sent to the battery monitoring device 204_p (the last device in the first group). At time point T_E, the downlink sensing command SC2 is sent to the battery monitoring device 204_(p + 1) (the last device in the second group).

[0043] In this embodiment, the uplink sensing command SC1 and the downlink sensing command SC2 are sent in parallel through the ring serial communication link 213 (although in different directions). Therefore, although each battery monitoring device has a propagation delay T_PD when forwarding the sensing command, the total propagation delay for broadcasting the sensing command to the battery monitoring devices 204_1 to 204_n can be reduced, and thus the time for determining the battery state such as SOC and SOH can be reduced. In addition, in the embodiment, the uplink sensing command SC1 can be used to instruct the battery monitoring devices 204_1 to 204_p to monitor the states of the battery modules 202_1 to 202_p, and the downlink sensing command SC2 can be used to instruct the battery monitoring devices 204_(p + 1) to 204_n to monitor the states of the battery modules 202_(p + 1) to 202_n.

[0044] In an embodiment, in order to further reduce the total propagation delay for the sensing command SC to reach all the battery monitoring devices 204_1 to 204_n, the value of p is set to a target number (e.g., an integer equal to or close to n / 2), which makes the number of battery monitoring devices receiving the uplink sensing command SC1 equal to or differ by only one device from the number of battery monitoring devices receiving the downlink sensing command SC2. For example, if n = 11, then p can be set to 5, such that the number of battery monitoring devices receiving the uplink sensing command SC1 (e.g., including BJB_AFE 210_1 and battery monitoring devices 204_1, …, 204_5) is the same as the number of battery monitoring devices receiving the downlink sensing command SC2 (e.g., including battery monitoring devices 204_6, …, 204_11). For another example, if n = 12, then p can be set to 6, such that the number of battery monitoring devices receiving the uplink sensing command SC1 is one more than the number of battery monitoring devices receiving the downlink sensing command SC2. For yet another example, if n = 12, then p can be set to 5, such that the number of battery monitoring devices receiving the uplink sensing command SC1 is one less than the number of battery monitoring devices receiving the downlink sensing command SC2. Therefore, the processes of the battery monitoring devices 210_1 and 204_1 to 204_p receiving the uplink sensing command SC1 and the processes of the battery monitoring devices 204_(p + 1) to 204_n receiving the downlink sensing command SC2 can be executed in parallel as efficiently as possible, thereby further reducing the total propagation delay for the sensing command SC to reach all the battery monitoring devices 210_1 and 204_1 to 204_n.

[0045] Figure 4B FIG. shows an example diagram of the process of sending the sensing command SC in the battery monitoring devices when n = 11 and p = 5 in an embodiment of the present invention. Refer to Figure 2B Description Figure 4B . As Figure 4B shown, at time point T_F, the bridge IC 208_1 sends the uplink sensing command SC1 to the BJB_AFE 210_1 and the downlink sensing command SC2 to the battery monitoring device 204_11 respectively through the ring serial communication link 213. At time point T_G, the uplink sensing command SC1 is sent to the battery monitoring device 204_5, and the downlink sensing command SC2 is sent to the battery monitoring device 204_6. Compared with Figure 3 the method of sending the sensing command SC shown in Figure 4B the method of sending the sensing command SC shown in can reduce the total propagation delay of the sensing command SC by half.

[0046] As described with respect to Figure 2A and / or Figure 2BAs mentioned, each of the battery monitoring devices 204_1 to 204_n may include a control circuit 216, a monitoring circuit 212, and a communication port 214. The control circuit 216 may be coupled to the monitoring circuit 212 and the communication port 214. In each of the battery monitoring devices 204_1 to 204_n, the corresponding control circuit 216 may control the corresponding monitoring circuit 212 to monitor the state of the corresponding battery module. In an embodiment, as further described below, the battery monitoring devices 204_1 to 204_n may start monitoring the states of the battery modules 202_1 to 202_n at the same time or approximately the same time according to the sensing command SC provided by the BMU 208. After obtaining the state information of the battery modules 202_1 to 202_n, the battery monitoring devices 204_1 to 204_n may send the state information of the battery modules 202_1 to 202_n to the BMU 208 through a serial communication link (e.g., including a linear serial communication link 211 or a ring serial communication link 213). Since the battery monitoring devices 204_1 to 204_n of the serial communication link 211 or 213 may sense the battery modules 202_1 to 202_n synchronously, the accuracy of determining the SOC and SOH of the battery modules 202_1 to 202_n is improved.

[0047] Specifically, as Figure 2AAs shown, for example, in the i-th battery monitoring device 204_i (i = 1, 2, ……, n) among the battery monitoring devices 204_1 to 204_n, the control circuit 216 can start the timing of the preset time delay PRE_DLYi when executing the sensing command SC, and can control the monitoring circuit 212 to sense the state of the corresponding battery module (i.e., the i-th battery module 202_i among the battery modules 202_1 to 202_n) at the sensing time point when the preset time delay PRE_DLYi expires. As further described below, the lengths of the preset time delays PRE_DLY1, PRE_DLY2, ……, PRE_DLYn (which can be collectively referred to as PRE_DLY) for the battery monitoring devices 204_1 to 204_n correspond to the lengths of the propagation delays T_PD associated with receiving or executing the sensing command SC (or SC1 or SC2) at each battery monitoring device and the position of the battery monitoring device in the serial communication link 211. (Herein, "position" refers to the position of the battery monitoring device 204_i in the serial communication link relative to other battery monitoring devices in the serial communication link: if the battery monitoring device 204_i is, for example, the third device in the serial communication link, its position is 3.) By compensating for the propagation delays at each of the battery monitoring devices 204_1 to 204_n in this way, the sensing time points of the battery modules 202_1 to 202_n are synchronized such that each battery monitoring device senses the state of its corresponding battery module at the same time or approximately the same time.

[0048] In an embodiment, the preset time delay PRE_DLY for the battery monitoring devices 204_1 to 204_n is configurable. The preset time delay PRE_DLY for the battery monitoring devices 204_1 to 204_n can be configured such that each of the battery monitoring devices starts monitoring the states of the battery modules 202_1 to 202_n at the same time or approximately the same time. The configuration of the preset time delay PRE_DLY will be described below with reference to Figure 3 Describe the configuration of the preset time delay PRE_DLY.

[0049] In an embodiment, the battery monitoring devices 204_1 to 204_n are in Figure 3The states of their respective battery modules are synchronously sensed at the time point T_B shown. For example, the first preset time delay PRE_DLY1 corresponding to the battery monitoring device 204_1 can be configured as P_DLY*(n - 1), the second preset time delay PRE_DLY2 corresponding to the battery monitoring device 204_2 can be configured as P_DLY*(n - 2), ……, and the nth preset time delay PRE_DLYn corresponding to the battery monitoring device 204_n can be configured as zero. In this embodiment, P_DLY is a preset time period and represents the propagation delay T_PD of each of the battery monitoring devices. Specifically, P_DLY can be configured to be equal to or approximately equal to the propagation delay T_PD. In an embodiment, the ith preset time delay PRE_DLYi of the battery monitoring device 204_i is determined according to the following equation:

[0050] PRE_DLYi = (n - i)*P_DLY. (1)

[0051] In Equation (1), PRE_DLYi represents the preset time delay of the battery monitoring device 204_i, n represents the total number of the battery monitoring devices 204_1 to 204_n in the linear serial communication link 211, P_DLY is equal to or approximately equal to T_PD, and i is an integer representing the position of the battery monitoring device 204_i in the linear serial communication link 211. For example, if the battery monitoring device 204_i is the first device (adjacent to the BJB 210) in the serial communication link 211, then i = 1; and if the battery monitoring device 204_i is the third device in the serial communication link 211, for example, then i = 3. In an embodiment, by presetting the time delays PRE_DLY1, PRE_DLY2, ……, PRE_DLYn for the battery monitoring devices 204_1 to 204_n according to Equation (1) respectively, the battery monitoring devices 204_1 to 204_n can synchronously (at the same time or approximately at the same time, for example, at the time point T_B) sense the states of their respective battery modules. The phrase "at the same time or approximately at the same time" means that there may be a time difference (e.g., due to the non-ideality of the circuit components in the battery monitoring system) between the time when the first battery monitoring device senses the state of the first battery module and the time when the second battery monitoring device senses the state of the second battery module, and this time difference is small enough to be negligible.

[0052] In an embodiment, the time delay PRE_DLYn of the battery monitoring device 204_n is preset to zero, and thus the battery monitoring devices 204_1 to 204_n sense the battery state synchronously at the time point T_B. However, the present invention is not limited thereto. In another embodiment, the time delay PRE_DLYn may be set to Δt1 (for example, a relatively short time interval), and thus the battery monitoring devices 204_1 to 204_n sense the battery state synchronously at the time point T_B + Δt1 (for example, Figure 3 the time point T_S1 shown in). More specifically, the first preset time delay PRE_DLY1 may be configured as P_DLY*(n - 1)+Δt1, the second preset time delay PRE_DLY2 may be configured as P_DLY*(n - 2)+Δt1,..., and the nth preset time delay PRE_DLYn may be configured as Δt1. The time interval Δt1 represents the difference between the time point T_B and the time point T_S1. The time interval Δt1 is configurable, and Δt1≥0. In an embodiment, the ith preset time delay PRE_DLYi is determined according to the following equation:

[0053] PRE_DLYi=(n - –i)*P_DLY+Δt1. (2)

[0054] In equation (2), PRE_DLYi represents the preset time delay of the battery monitoring device 204_i, n represents the total number of the battery monitoring devices 204_1 to 204_n in the linear serial communication link 211, P_DLY is equal to or approximately equal to T_PD, and i is an integer representing the position of the battery monitoring device 204_i in the linear serial communication link 211. In an embodiment, by presetting the time delays PRE_DLY1, PRE_DLY2,..., PRE_DLYn for the battery monitoring devices 204_1 to 204_n according to equation (2), the battery monitoring devices 204_1 to 204_n can sense the states (e.g., voltage) of their corresponding battery modules synchronously at the time point T_S1, for example.

[0055] In addition, in an embodiment, the BJB_AFE 210_1 also includes a control circuit that starts the preset time delay PRE_DLY0 when executing the sensing command SC, and controls the monitoring circuit to sense the state (e.g., current I BAT ) of the entire battery pack (including the battery modules 202_1 to 202_n) when the time delay PRE_DLY0 expires. The time delay PRE_DLY0 may be set such that when the battery monitoring devices 204_1 to 204_n sense the states (e.g., voltage) of the battery modules 202_1 to 202_n, the BJB_AFE 210_1 senses the battery current I of the battery pack BATTherefore, the current and voltage of the battery modules 202_1 to 202_n can be sensed synchronously.

[0056] For example, if the propagation delay T_PD0 of the BJB_AFE 210_1 is equal to or approximately equal to the propagation delay T_PD of the battery monitoring devices 204_1 to 204_n, and the preset time delay PRE_DLY of the battery monitoring devices 204_1 to 204_n is set according to Equation (1), then the preset time delay PRE_DLY0 of the BJB_AFE 210_1 can be set to be equal to n*P_DLY. Similarly, if the propagation delay T_PD0 of the BJB_AFE 210_1 is equal to or approximately equal to the propagation delay T_PD of the battery monitoring devices 204_1 to 204_n, and the preset time delay PRE_DLY of the battery monitoring devices 204_1 to 204_n is set according to Equation (2), then the preset time delay PRE_DLY0 of the BJB_AFE 210_1 can be set to be equal to n*P_DLY + Δt1. In other embodiments, if the propagation delay T_PD0 of the BJB_AFE 210_1 is very different from the propagation delay T_PD of the battery monitoring devices 204_1 to 204_n, then the preset time delay PRE_DLY0 of the BJB_AFE 210_1 can be set to be equal to T_PD0 + (n - 1)*P_DLY or equal to T_PD0 + (n - 1)*P_DLY + Δt1.

[0057] As mentioned above, in Figure 2A and Figure 3 example, the i-th preset time delay PRE_DLYi of the battery monitoring device 204_i can be determined according to Equation (1) or Equation (2), and the number "n" represents the total number of selected devices (e.g., the battery monitoring devices 204_1 to 204_n) in the linear serial communication link 211. Similarly, in an embodiment, Equation (1) or Equation (2) can be applied to Figure 2B the uplink 211 in Figure 4A e.g., including Figure 2B the BJB_AFE 210_1 and the AFE 204_1 to AFE 204_P shown in Figure 4A in which case the number "n" in Equation (1) or Equation (2) represents the total number "p + 1" of the devices 210_1 and 204_1 to 204_p in the uplink 211. Similarly, Equation (1) or Equation (2) can be applied to Figure 2B the downlink 213 in Figure 4A e.g., including Figure 4A the AFE 204_n to AFE 204_(p + 1) shown in in which case the number "n" in Equation (1) or Equation (2) represents the total number "n - p" of the devices 204_n to 204_(p + 1) in the downlink 213.

[0058] Now refer to Figure 2B the embodiment of Figure 4A shown, the time point T_D may represent the time when the battery monitoring device 204_p receives or executes the uplink sensing command SC1, and the time point T_E may represent the time when the battery monitoring device 204_(p + 1) receives or executes the downlink sensing command SC2. For illustration, consider an example where the battery monitoring devices 210_1 and 204_1 to 204_n start monitoring the states of the battery modules 202_1 to 202_n synchronously at the time point T_S2. The uplink of the ring serial communication link 213 includes the battery monitoring devices 210_1 and 204_1 to 204_p. The battery monitoring device 210_1 may be regarded as the first battery monitoring device in the uplink of the ring serial communication link 213, the battery monitoring device 204_1 may be regarded as the second battery monitoring device in the uplink of the ring serial communication link 213,..., and the battery monitoring device 204_p may be regarded as the (p + 1)th battery monitoring device in the uplink of the ring serial communication link 213.

[0059] If equation (2) is slightly modified, then the modified equation (2) can also be applied to the case of the uplink, such that the time delay PRE_DLY0 of the battery monitoring device 210_1 is configured as p*P_DLY + Δt2, the time delay PRE_DLY1 of the battery monitoring device 204_1 is configured as (p - 1)*P_DLY + Δt2,..., and the time delay PRE_DLYp of the battery monitoring device 204_p is configured as Δt2. Δt2 may represent the difference between the time point T_D and the time point T_S2 (see Figure 4A ).

[0060] Similarly, the downlink of the ring serial communication link 213 includes battery monitoring devices 204_(p + 1) to 204_n. The battery monitoring device 204_n can be considered as the first battery monitoring device in the downlink of the ring serial communication link 213, the battery monitoring device 204_(n - 1) can be considered as the second battery monitoring device in the downlink of the ring serial communication link 213, ……, and the battery monitoring device 204_(p + 1) can be considered as the (n - p)th battery monitoring device in the downlink of the ring serial communication link 213. Similarly, if the time delay PRE_DLYn of the battery monitoring device 210_n is configured as (n - p - 1)*P_DLY + Δt3, the time delay PRE_DLY(n - 1) of the battery monitoring device 204_(n - 1) is configured as (n - p - 2)*P_DLY + Δt3, ……, and the time delay PRE_DLY(p + 1) of the battery monitoring device 204_(p + 1) is configured as Δt3, then Equation (2) still applies. Δt3 can represent the difference between the time point T_E and the time point T_S2 (see Figure 4A ). In an embodiment, Δt2 and Δt3 are configurable. Δt2 and Δt3 can each represent a time interval greater than or equal to zero.

[0061] The setting of the p value may cause the time points T_D and T_E to appear in a certain order on the time axis. Specifically, if p + 1 < n - p, then the time point T_D is before the time point T_E (as shown in Figure 4A ); if p + 1 > n - p, then the time point T_D is after the time point T_E (not shown in Figure 4A ); and if p + 1 = n - p, then the time points T_D and T_E are at the same position on the time axis (as shown in Figure 4B ). In an embodiment, if the time point T_D is before the time point T_E, then Δt2 > Δt3 ≥ 0; if the time point T_D is after the time point T_E, then Δt3 > Δt2 ≥ 0; and if the time points T_D and T_E are at the same position on the time axis, then Δt3 = Δt2 ≥ 0. In an embodiment, by presetting the time delays PRE_DLY0 to PRE_DLYn for the battery monitoring devices 210_1 and 204_1 to 204_n respectively according to Equation (2) as described above, the battery monitoring devices 210_1 and 204_1 to 204_n can start monitoring the state of the battery module synchronously, for example, at the time point T_S2.

[0062] According to the above embodiments, the preset time delay PRE_DLYi of the battery monitoring device 204_i can be determined based on the position of the battery monitoring device 204_i in a serial communication link (e.g., the uplink of the linear serial communication link 211, the uplink of the ring serial communication link 213, or the downlink of the ring serial communication link 213) and the propagation delay T_PD of the battery monitoring device 204_i.

[0063] As mentioned above, each of the battery modules 202_1 to 202_n (hereinafter referred to as the battery module 202) may include a plurality of battery cells, and the corresponding battery monitoring devices among the devices 204_1 to 204_n (hereinafter referred to as the battery monitoring device 204) may monitor the states of the battery cells. In an embodiment, the monitoring circuit 212 of the battery monitoring device 204 may perform a first sensing operation on each of the plurality of battery cells at their respective first time points to obtain first sensing data, and perform a second sensing operation on each battery cell at their respective second time points to obtain second sensing data. The monitoring circuit 212 may also generate information indicating the state of the battery module 202 based on the first sensing data and the second sensing data. The control circuit 216 of the battery monitoring device 204 may also control the communication port 214 to send the information indicating the state of the battery module 202 to the BMU 208 via a serial communication link (e.g., including the linear serial communication link 211 or the ring serial communication link 213). The following will be combined with Figure 5 illustrate this embodiment.

[0064] Figure 5 FIG. shows an example process diagram of the battery monitoring device 204 monitoring a plurality of battery cells BAT1 to BATM (M = 2, 3,...) in the battery module 202 in an embodiment of the present invention. As Figure 5As shown, the monitoring circuit 212 of the battery monitoring device 204 may sense the states of battery cells BAT1 to BATM in sequence according to a first order in a first set of time frames, and may sense the states of battery cells BAT1 to BATM in sequence according to a second order (where the second order is opposite to the first order) in a second set of time frames after the first set of time frames. In each time frame of the first set of time frames and the second set of time frames, the monitoring circuit 212 monitors the state of the corresponding battery cell among battery cells BAT1 to BATM, and the monitoring circuit 212 may set the first set of time frames and the second set of time frames to have the same duration. Specifically, the monitoring circuit 212 may perform a first sensing operation (e.g., sensing the voltage of the battery cell) in a time frame starting at time point T1 for the first battery cell BAT1 to obtain first sensing data (e.g., including a first sensed voltage) (the first operation is indicated by an arrow starting at time point T1), and may also perform a second sensing operation (e.g., sensing the voltage of the battery cell) in a time frame starting at time point T(2M) for the first battery cell BAT1 to obtain second sensing data (e.g., including a second sensed voltage) (the second operation is indicated by an arrow starting at time point T(2M)). Similarly, the monitoring circuit 212 may perform: a first sensing operation in a time frame starting at time point T2 and a second sensing operation in a time frame starting at time point T(2M - 1) for the second battery cell BAT2 to obtain first sensing data and second sensing data respectively, ……, and a first sensing operation in a time frame starting at time point TM and a second sensing operation in a time frame starting at time point T(M + 1) for the Mth battery cell BATM to obtain first sensing data and second sensing data respectively.

[0065] In an embodiment, the time interval between time point T1 and time point T(2M) includes an intermediate time point, such as (T1 + T(2M)) / 2, which may be referred to as the center or intermediate sensing time point of the first battery cell BAT1. The center or intermediate sensing time point of the first battery cell BAT1 may be represented by Figure 5 the T in C . Similarly, the intermediate sensing time point of the second battery cell BAT2 is the time point (T2 + T(2M - 1)) / 2, which is also represented by T C ; the intermediate sensing time point of the third battery cell BAT3 is the time point (T3 + T(2M - 2)) / 2, which is also represented by TC; ……; and the intermediate sensing time point of the Mth battery cell BATM is the time point (TM + T(M + 1)) / 2, which is also represented by T CThat is, the time points (T1 + T(2M)) / 2, (T2 + T(2M-1)) / 2, ……, and (TM + T(M+1)) / 2 coincide with each other, for example, are the same or approximately the same: Due to non-idealities of circuit components, for example, there may be differences between each of these intermediate sensing time points, but the differences are relatively small and negligible.

[0066] The first sensed data of battery cell BATj (j = 1, 2, ……, M) may include the first sensed voltage of battery cell BATj monitored at time point Tj, and the second sensed data of battery cell BATj may include the second sensed voltage of battery cell BATj monitored at time point T(2M+1-j). In a relatively stable situation (for example, when the charging current or discharging current of battery module 202 is relatively stable or unchanged), the average value of the first sensed voltage and the second sensed voltage of battery cell BATj in battery module 202 may represent the voltage of battery cell BATj at the central time point T C . The battery monitoring device 204 may calculate the average value of the first sensed voltage and the second sensed voltage for each of battery cells BAT1 to BATM. The calculated average value may represent the voltage of battery cells BAT1 to BATM at the central time point T C . Therefore, it can be considered that the voltages of battery cells BAT1 to BATM are sensed synchronously at the central time point T C . Thus, the accuracy of monitoring the states of battery cells BAT1 to BATM can be further improved.

[0067] In Figure 5 an embodiment, the monitoring circuit 212 of the battery monitoring device 204 may include an Analog to Digital Converter (ADC for short) to monitor the states of all battery cells in battery module 202. However, the present invention is not limited thereto. In another embodiment, the monitoring circuit 212 of the battery monitoring device 204 may include multiple ADCs, and the battery cells in battery module 202 may be divided into multiple groups (or multiple parts). Each ADC among the ADCs may perform the above-mentioned first sensing operation and second sensing operation for each battery cell in the corresponding group of battery cells. The multiple ADCs may monitor the states of the battery cell groups in parallel to speed up the monitoring process. The following combination with Figure 6 shows an example.

[0068] Figure 6 FIG. shows an example process diagram of the battery monitoring device 204 monitoring multiple battery cells BAT1 to BAT(2K) (K = 1, 2, 3, ……) in a battery module in an embodiment of the present invention. In Figure 6In the example, the monitoring circuit 212 of the battery monitoring device 204 includes two ADCs (ADC1 and ADC2). As Figure 6 shown, ADC1 can perform: a first sensing operation in a time frame starting at time point T1 for the (K + 1)-th battery cell BAT(K + 1) and a second sensing operation in a time frame starting at time point T(2K); a first sensing operation in a time frame starting at time point T2 for the (K + 2)-th battery cell BAT(K + 2) and a second sensing operation in a time frame starting at time point T(2K - 1);..., and a first sensing operation in a time frame starting at time point TK for the 2K-th battery cell BAT(2K) and a second sensing operation in a time frame starting at time point T(K + 1). ADC2 can perform: a first sensing operation in a time frame starting at time point T1 for the K-th battery cell BATK and a second sensing operation in a time frame starting at time point T(2K); a first sensing operation in a time frame starting at time point T2 for the (K - 1)-th battery cell BAT(K - 1) and a second sensing operation in a time frame starting at time point T(2K - 1);..., and a first sensing operation in a time frame starting at time point T(K) for the first battery cell BAT1 and a second sensing operation in a time frame starting at time point T(K + 1). In this example, similar to the Figure 5 embodiment shown in, the intermediate sensing time point of each of the battery cells BAT1 to BAT(2K) can be represented by time point T' C . That is, it can be considered that the battery monitoring device 204 synchronously monitors the battery cells BAT1 to BAT(2K) at time point T' C .

[0069] Figure 5 And Figure 6 describe embodiments in which one or more ADCs perform two sensing operations on battery cells in the time frames of the monitoring process. However, the present invention is not limited thereto. In another embodiment, the battery module can include M battery cells (M = 2, 3,...) and M ADCs. In each time frame of the monitoring process, the ADCs can perform sensing operations on the battery cells in parallel to minimize the time of the sensing process. The ADCs can perform sensing operations on the battery cells once in each time frame of the monitoring process.

[0070] Figure 7 FIG. 700 shows an exemplary flowchart of a method for monitoring multiple battery modules (e.g., 202_1 to 202_n) in an embodiment of the present invention. Although in Figure 7Specific steps are disclosed, but these steps are examples for illustrative purposes. That is, the embodiments according to the present invention are also suitable for performing various other steps or Figure 7 variations of the steps described Figure 2A in Figure 2B combination with Figure 3 、 Figure 4A 、 Figure 4B 、 Figure 5 and Figure 6 as described Figure 7 .

[0071] At step 702, a battery monitoring device 204_i (i = 1, 2, ……, n) among a group of battery monitoring devices 204_1 to 204_n receives a sensing command SC sent by a battery management unit 208 via a serial communication link (e.g., 211 or 213). The serial communication link includes the battery monitoring devices 204_1 to 204_n.

[0072] At step 704, the battery monitoring device 204_i starts timing a preset time delay PRE_DLY when the battery monitoring device 204_i starts to execute the sensing command SC.

[0073] At step 706, the battery monitoring devices 204_1 to 204_n sense the states of the battery modules 202_1 to 202_n at a sensing time point. More specifically, the battery monitoring device 204_i senses the state of the battery module 202_i when the preset time delay PRE_DLY expires, such that the battery monitoring device 204_i senses the state of the battery module 202_i at a time point synchronized with the above-mentioned sensing time point.

[0074] At step 708, the battery monitoring device 204_i sends information including the state of the battery module 202_i to the battery management unit 208 via the serial communication link.

[0075] Therefore, an embodiment according to the present invention provides a battery monitoring system. In an embodiment, the battery monitoring system includes a plurality of monitoring devices, and the plurality of monitoring devices can synchronously sense the states of battery modules by setting a time delay for the start time points of their sensing processes. Therefore, the accuracy of determining the states of battery modules such as the state of charge (SOC) and the state of health (SOH) can be improved. In an embodiment, the monitoring device (or each of the plurality of monitoring devices) can also sense the voltage of each of a plurality of battery cells in the battery module twice during a preset period to obtain two voltages, and can calculate the average value of the two voltages. Therefore, the monitoring device can provide a set of voltage average values for representing at a time point (e.g., the above-mentioned intermediate time point T C or T' CThe cell voltage values of multiple battery cells measured synchronously at []. This can further improve the accuracy of determining the SOC and SOH of the battery module.

[0076] In addition, in an embodiment, the BMU 208 may periodically send a sensing command SC to the battery module to obtain / acquire multiple sets of data over multiple cycles or time frames. Among them, each set of data is obtained / acquired in a corresponding one of these cycles / time frames. The BMU 208 may analyze the multiple sets of data based on Electrochemical Impedance Spectroscopy (EIS) and Fast Fourier Transform (FFT) to generate an impedance spectrum. The impedance spectrum of the battery module can be used to determine or estimate the SOC and SOH of the battery module. The impedance spectrum of the battery module can also be used to estimate the internal temperature of each battery module to further improve the accuracy of determining the SOC of the battery module.

[0077] In an embodiment, EIS provides a technique for transforming a resistance time graph (e.g., a time-domain graph) into an impedance spectrum (e.g., a frequency-domain graph). In an embodiment, the FFT technique provides a method for performing the transformation.

[0078] In an embodiment, as mentioned above, the current and voltage of the battery modules 202_1 to 202_n can be sensed synchronously, and they can be sensed periodically. The BMU 208 may obtain / acquire the current values I of the battery modules 202_1 to 202_n measured synchronously in the first cycle / time frame BATA and the voltage values V1 A , V2 A , ……, Vn A (hereinafter referred to as the first data set), and obtain / acquire the current values I of the battery modules 202_1 to 202_n measured synchronously in the second cycle / time frame after the first cycle / time frame BATB and the voltage values V1 B , V2 B , ……, Vn B (hereinafter referred to as the second data set). The BMU 208 may estimate the internal resistance of the battery modules 202_1 to 202_n based on the first data set and the second data set.

[0079] For example, the battery module 202_1 includes multiple battery cells and an internal resistance R1. Therefore, in the first cycle or time frame, the voltage V1 of the battery module 202_1 A can be given by the following formula: V1 A =V CELLSA +I BATA *R1, where VCELLSA Represents the total voltage of the battery cells in battery module 202_1. In the second cycle or time frame, the voltage V1 of battery module 202_1 B can be given by the following formula: V1 B = V CELLSB + I BATB * R1, where V CELLSB represents the total voltage of the battery cells in battery module 202_1. In an embodiment, the time gap between the first cycle and the second cycle (or time frame) is relatively short, so the total voltage of the battery cells is relatively stable. For example, V CELLSB = V CELLSA . Therefore, the internal resistance R1 of battery module 202_1 can be calculated as follows: R1 = (V1 B - V1 A ) / (I BATB - I BATA ). Similarly, the internal resistances R2, R3,..., Rn of battery modules 202_2 to 202_n can be calculated as follows: R2 = (V2 B - V2 A ) / (I BATB - I BATA ), R3 = (V3 B - V3 A ) / (I BATB - I BATA ),..., Rn = (Vn B - Vn A ) / (I BATB - I BATA ).

[0080] Therefore, the BMU 208 can periodically measure the battery current I of battery modules 202_1 to 202_n BATand battery voltages V1, V2, …… and Vn, such that the BMU 208 can calculate / obtain multiple values (multiple internal resistance values) of the internal resistance of battery module 202_1, multiple values (multiple internal resistance values) of the internal resistance of battery module 202_2, ……, and multiple values (multiple internal resistance values) of the internal resistance of battery module 202_n. The BMU 208 can also apply a fast Fourier transform to the multiple values (multiple internal resistance values) of the internal resistance to generate an impedance spectrum for each of battery modules 202_1 to 202_n. In an embodiment, the impedance spectrum of a battery module may have a specific pattern under specific circumstances. For example, when the battery module is in an idle state (or in a sleep mode), the impedance spectrum of the battery module may include a first pattern. When the battery module is in a fast charging mode, the impedance spectrum of the battery module may include a second pattern. When the battery module switches from the sleep mode to the active mode, the impedance spectrum of the battery module may include a third pattern. Thus, the BMU 208 can determine whether the battery module is in a healthy state by analyzing the real-time impedance spectrum of the battery module. Additionally, in an embodiment, the information in the impedance spectrum of the battery module may indicate the internal temperature and / or SOC of the battery module. Thus, the BMU 208 can improve the estimation of the SOC of the battery module based on the real-time impedance spectrum. A detailed description will be provided below in conjunction with Figure 8 and Figure 9 provide a detailed description.

[0081] According to Fourier's theorem, any periodic function can be represented as the sum of sine functions (sine and cosine) with different frequencies, amplitudes, and phase shifts. Aperiodic functions can also be represented by a series of sine components using the fast Fourier transform.

[0082] Figure 8 An example diagram for explaining the fast Fourier transform is shown. Figure 8 shows parameter P T whose value changes with time in a graph 802. The relationship between parameter P T and time can be represented by a function: P T = f(t). The function P T = f(t) can be represented by a series of sine components P Figure 8 shown (as F1 、A F2 、A F3 etc.) with different frequencies F1, F2, F3, etc. and different amplitudes A F1 、P F2 、P F3 、P T . By applying the fast Fourier transform to parameter P T , a frequency domain graph 804 of parameter P F1 、P F2 、PF3 Information such as

[0083] Figure 9 Fig. shows an example of converting a set of calculated internal resistance values of a battery module into an impedance spectrum of the battery module in an embodiment of the present invention. In combination with Figure 2A , Figure 2B , Figure 3 , Figure 4A , Figure 4B , Figure 5 , Figure 6 , Figure 7 and Figure 8 describe Figure 9 .

[0084] As mentioned above, the currents and voltages of the battery modules 202_1 to 202_n can be sensed synchronously and periodically. In the Figure 9 example, I 0P , I 1P , I 2P etc. can respectively represent the values of the battery current I 0P , t 1P , t 2P obtained by the BMU 208 at etc. The values of the battery voltages of the battery module 202_i (i = 1, 2,..., n) can be represented by V BAT , V 0P , V 1P etc. respectively obtained by the BMU 208 at time t 2P , t 0P , t 1P , t 2P etc. The internal resistance value R 1P of the battery module 202_i at time t 1P can be given by the following formula: R 1P = (V 1p - V 0p ) / (I 1p - I 0p ). The internal resistance values R 2P , R 3P etc. can be calculated in a similar manner. Therefore, the BMU 208 can obtain a set of internal resistance values R 1P , R 2P , R 3P etc. of the battery module 202_i.

[0085] In an embodiment, the BMU 208 can apply a fast Fourier transform to the internal resistance values R 1P , R 2P , R 3P etc. of the battery module 202_i to generate information about the impedance spectrum of the battery module 202_i. In Figure 9In the frequency domain graph 902, an example of an impedance spectrum associated with the internal resistance of the battery module 202_i is shown. Information about the impedance spectrum may include a plurality of frequency values (e.g., including F A 、F B 、F C etc.) and a plurality of amplitude values corresponding to the frequency values respectively (e.g., including AM A 、AM B 、AM C etc.).

[0086] In an embodiment, as used herein, phrases such as "applying a fast Fourier transform to the internal resistance value" refer to applying a fast Fourier transform algorithm to the internal resistance value to generate the result of the algorithm, and the result includes information about the impedance spectrum. For example, an algorithm module for fast Fourier transform (e.g., represented by computer-readable instructions) may be stored in the storage unit (e.g., non-transitory computer storage medium) of the BMU 208. The BMU 208 may execute the algorithm module based on the internal resistance value, or in other words, the BMU 208 may input the internal resistance value into the algorithm module. Therefore, the BMU 208 may obtain information about the impedance spectrum from the algorithm module.

[0087] As mentioned above, the impedance spectrum of the battery module 202_i may have a specific pattern under specific circumstances. If the battery module 202_i is in a healthy state, the information of the real-time impedance spectrum will match the information of the pre-stored impedance spectrum. More specifically, in an embodiment, before mass-producing the battery module, a test process is performed on a sample of the battery module. The test process may include measuring the current and voltage of the sample of the battery module (hereinafter referred to as the battery module sample) under different conditions (e.g., different operating modes, different SOCs, different temperatures, etc.). The test process may also include generating information about the impedance spectrum of the battery module sample (hereinafter referred to as post-test information) based on the measurement results. In an embodiment, the post-test information may be pre-stored in a storage unit (e.g., non-transitory computer storage medium). The BMU 208 may obtain the post-test information from the storage unit.

[0088] Therefore, in an embodiment, if the real-time information of the impedance spectrum of the battery module does not match the pre-stored impedance spectrum information, the BMU 208 may determine that there is a fault or potential fault in the battery module. In an embodiment, when the difference between the first impedance spectrum and the second impedance spectrum is greater than a preset threshold or outside a predetermined standard, the first impedance spectrum and the second impedance spectrum do not match.

[0089] In addition, during the testing process, a comparison table or a comparison database of impedance spectra and SOC can be generated by mapping the impedance spectra to the SOC of the battery module sample. Similar to the post-test information, the comparison database of impedance spectra and SOC can be stored in the storage unit mentioned above. Therefore, the BMU 208 can determine the SOC of the battery module by comparing the real-time information of the impedance spectra with the impedance spectrum information in the comparison database.

[0090] In addition, during the testing process, a comparison table or a comparison database of impedance spectra and temperature can be generated by mapping the impedance spectra to the internal temperature of the battery module sample. The comparison database of impedance spectra and temperature can be stored in the storage unit mentioned above. Therefore, the BMU 208 can determine the internal temperature of the battery module by comparing the real-time information of the impedance spectra with the impedance spectrum information in the comparison database. The determined internal temperature value can be used to further improve the accuracy of determining the SOC of the battery module.

[0091] In addition, as mentioned above, the currents and voltages of the battery modules 202_1 to 202_n can be sensed synchronously and periodically. Therefore, the BMU 208 can generate a set of impedance spectra corresponding to the battery modules 202_1 to 202_n respectively, and these impedance spectra can represent the states of the battery modules 202_1 to 202_n at the same time or within the same time frame. In an embodiment, the BMU 208 can compare these impedance spectra with each other to determine whether there is a faulty (or potentially faulty) battery module among the battery modules 202_1 to 202_n. For example, if the BMU 208 identifies an impedance spectrum that is very different from other impedance spectra, the BMU 208 can determine that the battery module corresponding to the different impedance spectrum is faulty (or potentially faulty).

[0092] Therefore, according to an embodiment of the present invention, a battery monitoring system is provided, which synchronously and periodically measures / senses the battery current and battery voltage of a set of battery modules. Based on the synchronously and periodically measured current and voltage, the battery monitoring system can calculate multiple sets of internal resistance values of the battery modules, and apply a fast Fourier transform to these internal resistance values to generate impedance spectrum information of the battery modules. The battery monitoring system can also analyze the impedance spectra to determine, for example, the SOC, SOH, and / or internal temperature of the battery modules. In addition, in an embodiment, the battery monitoring system can compare these impedance spectra with each other to determine whether there is a faulty (or potentially faulty) battery module among these battery modules.

[0093] Although the foregoing description and drawings illustrate embodiments of the present invention, it should be understood that various additions, modifications, and substitutions can be made to the present invention without departing from the spirit and scope of the principles of the present invention as defined by the appended claims. Those skilled in the art will understand that the present invention can be used with many modifications to form, structure, arrangement, proportion, material, elements, and components, and in other ways for the practice of the present invention, which modifications are particularly suitable for specific environments and operating requirements without departing from the principles of the present invention. Therefore, the presently disclosed embodiments are considered illustrative rather than restrictive in all respects, and the scope of the present invention is indicated by the appended claims and their legal equivalents and is not limited to the foregoing description.

Claims

1. A battery monitoring device, comprising: a monitoring circuit operable to sense a state of the first battery module; a communication port operable to receive a sensing command provided by a battery management unit via a serial communication link, wherein the serial communication link includes a plurality of battery monitoring devices including the battery monitoring device, wherein the plurality of battery monitoring devices are coupled to a plurality of battery modules including the first battery module, and wherein each of the plurality of battery monitoring devices is operable to sense a state of a corresponding battery module of the plurality of battery modules at a sensing time point; and A control circuit, wherein the control circuit is coupled to the monitoring circuit and the communication port, and is operable to start the timing of a preset time delay when the control circuit starts to execute the sensing command, and is also operable to control the monitoring circuit to sense the state of the first battery module when the preset time delay expires, so that the monitoring circuit senses the state of the first battery module at a time point synchronized with the sensing time point, and wherein the control circuit is also operable to control the communication port to send information including the sensed state of the first battery module to the battery management unit via the serial communication link.

2. The battery monitoring device according to claim 1, wherein: The battery monitoring device is operable to forward the sensing command to a next battery monitoring device among the plurality of battery monitoring devices in the serial communication link, and wherein the length of the preset time delay is determined based on a position of the battery monitoring device in the serial communication link and based on a propagation delay between when the battery monitoring device receives the sensing command and when the next battery monitoring device receives the sensing command.

3. The battery monitoring device according to claim 2, wherein: The length of the preset time delay is determined according to the following equation: T=(ni)*P_DLY+Δt, Wherein, T represents the preset time delay, n represents the total number of the battery monitoring devices in the serial communication link, i is a number representing the position of the battery monitoring device in the serial communication link, Δt represents a time interval greater than or equal to zero, and P_DLY represents the propagation delay of the battery monitoring device.

4. The battery monitoring device according to claim 1, wherein: The first battery module includes a plurality of battery cells, wherein the monitoring circuit is operable to perform a first sensing operation on each of the plurality of battery cells at its respective first time point, and to perform a second sensing operation on each of the battery cells at its respective second time point, wherein the time interval between each respective first time point and each respective second time point has a corresponding intermediate time point, and wherein the intermediate time points of the plurality of battery cells coincide with each other.

5. The battery monitoring device according to claim 4, wherein: The monitoring circuit includes at least two analog-to-digital converters, and wherein each of the at least two analog-to-digital converters is operable to perform the first sensing operation and the second sensing operation on a portion of the plurality of battery cells.

6. A battery monitoring system comprising: A serial communication link comprising a plurality of battery monitoring devices operable to sense states of a plurality of battery modules at a sensing time point, wherein the plurality of battery monitoring devices comprises a first battery monitoring device, and wherein the first battery monitoring device comprises: a monitoring circuit operable to sense a state of a first battery module among the plurality of battery modules; a communication port operable to receive a first sensing command from a battery management unit via the serial communication link; and A control circuit, wherein the control circuit is coupled to the monitoring circuit and the communication port and is operable to execute the first sensing command, is operable to start the timing of a preset time delay when the control circuit starts to execute the first sensing command, and is operable to control the monitoring circuit to sense the state of the first battery module when the preset time delay expires, so that the monitoring circuit senses the state of the first battery module at a time point synchronized with the sensing time point, and wherein the control circuit is also operable to control the communication port to send information including the sensed state of the first battery module to the battery management unit via the serial communication link.

7. The battery monitoring system according to claim 6, wherein: The first battery monitoring device is operable to forward the first sensing command to a second battery monitoring device among the plurality of battery monitoring devices in the serial communication link, and wherein the length of the preset time delay is determined based on a position of the first battery monitoring device in the serial communication link and based on a propagation delay between when the first battery monitoring device receives the first sensing command and when the second battery monitoring device receives the first sensing command.

8. The battery monitoring system according to claim 7, wherein: The length of the preset time delay is determined according to the following equation: T=(ni)*P_DLY+Δt, Wherein, T represents the preset time delay, n represents the total number of the battery monitoring devices in the serial communication link, i is a number representing the position of the first battery monitoring device in the serial communication link, Δt represents a time interval greater than or equal to zero, and P_DLY represents the propagation delay of the first battery monitoring device.

9. The battery monitoring system according to claim 6, wherein: The first battery module includes a plurality of battery cells, wherein the monitoring circuit is operable to perform a first sensing operation on each of the plurality of battery cells at its respective first time point, and to perform a second sensing operation on each of the battery cells at its respective second time point, wherein the time interval between each of the first time point and each of the second time point has a corresponding intermediate time point, and wherein the intermediate time points of the plurality of battery cells coincide with each other.

10. The battery monitoring system according to claim 9, wherein: The monitoring circuit is operable to perform the first sensing operation to obtain a first sensing voltage and is also operable to perform the second sensing operation to obtain a second sensing voltage, and wherein the battery management unit is operable to calculate an average of the first sensing voltage and the second sensing voltage.

11. The battery monitoring system according to claim 6, wherein: The serial communication link comprises a ring-shaped serial communication link, wherein the first sensing command is transmitted via an uplink of the ring-shaped serial communication link, and wherein a second sensing command generated by the battery management unit is transmitted via a downlink of the ring-shaped serial communication link.

12. The battery monitoring system according to claim 6, wherein: The battery monitoring system is operable to periodically and synchronously sense the current flowing through the plurality of battery modules and the voltage of the first battery module to obtain a plurality of data sets. wherein each of the plurality of data sets comprises a value of the current and a value of the voltage measured in one time frame of a plurality of time frames, and The battery monitoring system is operable to calculate a plurality of values ​​of the internal resistance of the first battery module, and wherein each of the plurality of values ​​is calculated based on a value in a first data set of the plurality of data sets and a value in a second data set of the plurality of data sets.

13. The battery monitoring system according to claim 12, wherein: The battery monitoring system is operable to apply a fast Fourier transform to the plurality of values ​​to generate information regarding an impedance spectrum of the first battery module.

14. A method for monitoring a plurality of battery modules, the method comprising: receiving, using a first battery monitoring device among a plurality of battery monitoring devices, a first sensing command sent by a battery management unit via a serial communication link, wherein the serial communication link includes the plurality of battery monitoring devices; When the first battery monitoring device starts to execute the first sensing command, starting the timing of the preset time delay; sensing the states of the plurality of battery modules at sensing time points using the plurality of battery monitoring devices, wherein the first battery monitoring device senses the state of a first battery module among the plurality of battery modules when the preset time delay expires, so that the first battery monitoring device senses the state of the first battery module at a time point synchronized with the sensing time point; and Information including the sensed status of the first battery module is sent to the battery management unit via the serial communication link.

15. The method according to claim 14, further comprising: forwarding, using the first battery monitoring device, the first sense command to a second battery monitoring device among the plurality of battery monitoring devices in the serial communication link; as well as The length of the preset time delay is determined based on the position of the first battery monitoring device in the serial communication link and based on a propagation delay between when the first battery monitoring device receives the first sense command and when the second battery monitoring device receives the first sense command.

16. The method according to claim 15, wherein: The length of the preset time delay is determined according to the following equation: T=(ni)*P_DLY+Δt, Wherein, T represents the preset time delay, n represents the total number of the battery monitoring devices in the serial communication link, i is a number representing the position of the first battery monitoring device in the serial communication link, Δt represents a time interval greater than or equal to zero, and P_DLY represents the propagation delay of the first battery monitoring device.

17. The method according to claim 14, wherein: The first battery module includes a plurality of battery cells, and wherein the method further includes: performing a first sensing operation on each battery cell of the plurality of battery cells at its respective first time point to obtain first sensing data; performing a second sensing operation on each of the battery cells at its respective corresponding second time point to obtain second sensing data, wherein a time interval between each of the first time point and each of the second time point has a corresponding intermediate time point, and wherein the intermediate time points of the plurality of battery cells coincide with each other; and Information including a sensed state of the first battery module is generated according to the first sensing data and the second sensing data.

18. The method according to claim 17, wherein: Generating information including the sensed state includes: performing the first sensing operation to obtain a first sensing voltage; performing the second sensing operation to obtain a second sensing voltage; and An average value of the first sensing voltage and the second sensing voltage is calculated.

19. The method according to claim 14, wherein: The serial communication link comprises a ring serial communication link, and wherein the method further comprises: sending the first sensing command via an uplink of the ring-shaped serial communication link; and A second sensing command generated by the battery management unit is transmitted via a downlink of the ring-shaped serial communication link.

20. The method of claim 14, further comprising: periodically synchronously sensing the current flowing through the plurality of battery modules and the voltage of the first battery module to obtain a plurality of data sets, wherein each of the plurality of data sets includes a value of the current and a value of the voltage measured in one time frame of a plurality of time frames; calculating a plurality of values ​​of the internal resistance of the first battery module, wherein each of the plurality of values ​​is calculated based on a value in a first data set of the plurality of data sets and a value in a second data set of the plurality of data sets; and A fast Fourier transform is applied to the plurality of values ​​to generate information regarding an impedance spectrum of the first battery module.

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