Abnormality detection method in battery management system and battery management system

Abstract

An abnormality detection method in a battery management system and a battery management system are provided. The method comprises: a control unit controls a first switch to sequentially disconnect a first time period, connect a second time period, and disconnect a third time period; a control unit controls a measuring unit to measure a voltage value on a first capacitor at the end of the first time period as a measured voltage value of a first single cell; a control unit controls a measuring unit to measure a voltage value on the first capacitor at at least one time point in the third time period as a measured capacitor voltage value, and obtains a measured time constant based on at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single cell; if the measured time constant exceeds a preset range of a theoretical time constant, the control unit determines that an abnormality occurs in the battery management system. By taking the change curve (time constant) of the voltage value on the first capacitor as a comparison object, various abnormalities occurring in the battery management system can be accurately detected, thereby improving the detection accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to an abnormality detection method in a battery management system. Background Art

[0002] In practical applications, nickel strips or wires are usually used as connecting wires to connect the battery management system to each single cell, so that the battery management system can measure the voltage of each single cell and perform corresponding protection operations. It can be seen that when the connecting wire or related components in the battery management system are abnormal, the measured voltage of each single cell is inaccurate, which in turn causes the battery management system to perform some erroneous protection operations. At present, the traditional method uses the voltage value on the capacitor in the battery management system to be compared with the disconnection threshold V CTO However, the conventional method can only detect the incorrect voltage of each single cell caused by abnormal connection, which may lead to misjudgment and cause the battery management system to perform some wrong protection operations. Summary of the invention

[0003] The present invention provides an abnormality detection method in a battery management system. The battery management system includes a measuring unit, a control unit, a first monitoring resistor, a second monitoring resistor, a first capacitor, a first switch and a first equalizing resistor, wherein the first single cell in the battery pack is coupled to the first monitoring resistor, the second monitoring resistor, the first capacitor, the first switch and the first equalizing resistor. The method includes: calculating the theoretical time constant corresponding to the first single cell when the battery management system does not have an abnormality; determining the preset range of the theoretical time constant according to the theoretical time constant; and performing the following steps to detect the first single cell to determine whether the battery management system has an abnormality: the control unit controls the first switch to disconnect the first time period in sequence, connect the second time period, and disconnect the third time period; the control unit controls the measuring unit to measure the voltage value on the first capacitor at the end of the first time period as the measured voltage value of the first single cell; the control unit controls the measuring unit to measure the voltage value on the first capacitor at at least one time point in the third time period as the measured capacitor voltage value, and obtains the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single cell; and if the measured time constant exceeds the preset range of the theoretical time constant, the control unit determines that the battery management system has an abnormality.

[0004] The present invention provides a battery management system. The system includes: a measuring unit, a control unit coupled to the measuring unit, a first monitoring resistor coupled to the measuring unit, a second monitoring resistor coupled to the measuring unit, a first capacitor coupled to the measuring unit, a first switch coupled to the measuring unit; and a first equalizing resistor coupled to the measuring unit, wherein a first single cell in a battery pack is coupled to the first monitoring resistor, the second monitoring resistor, the first capacitor, the first switch and the first equalizing resistor; wherein the battery management system is configured to execute a method including the following steps: calculating a theoretical time constant corresponding to a first single cell when no abnormality occurs in the battery management system; determining a preset range of the theoretical time constant according to the theoretical time constant; the control unit controls the first switch to sequentially disconnect the first time period, conduct the second time period, and disconnect the third time period; the control unit controls the measuring unit to measure the voltage value on the first capacitor at the end of the first time period as the measured voltage value of the first single cell; the control unit controls the measuring unit to measure the voltage value on the first capacitor at at least one time point in the third time period as the measured capacitor voltage value, and obtains the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single cell; and if the measured time constant exceeds the preset range of the theoretical time constant, the control unit determines that an abnormality occurs in the battery management system.

[0005] The present invention determines the preset range of the theoretical time constant when no abnormality occurs in the battery management system, and then controls the on and off of the first switch and calculates the measured time constant. The measured time constant is compared with the preset range of the theoretical time constant to determine whether an abnormality occurs in the battery management system. The method uses the change curve (time constant) of the voltage value on the first capacitor as the comparison object, and can accurately detect various abnormalities occurring in the battery management system, thereby improving the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following description in combination with some embodiments of the present invention and the accompanying drawings may further provide an understanding of the objectives, specific structural features and advantages of the present invention.

[0007] Figure 1 FIG. 1 is a block diagram of a battery management system according to an embodiment of the present invention;

[0008] Figure 2 The figure shows a circuit diagram for detecting a single cell CELLj to determine whether an abnormality occurs in a battery management system according to an embodiment of the present invention;

[0009] Figure 3 The figure shows a voltage variation curve on the capacitor CFj when no abnormality occurs in the battery management system according to an embodiment of the present invention;

[0010] Figure 4Shown is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention;

[0011] Figure 5 FIG. 1 is a curve showing a voltage variation on a capacitor CFj according to an embodiment of the present invention;

[0012] Figure 6 Shown is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention;

[0013] Figure 7 Shown is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention;

[0014] Figure 8 Shown is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention;

[0015] Fig. 9 Shown is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention;

[0016] Fig.10 The voltage variation curve on the capacitor CFj according to one embodiment of the present invention is shown;

[0017] Fig.11 It is a flow chart of an abnormality detection method in a battery management system according to one embodiment of the present invention; and

[0018] Fig.12 FIG. 1 is a flow chart of an abnormality detection method in a battery management system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will provide a detailed description of embodiments of the present invention. Although the present invention is described and illustrated by these embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, the present invention encompasses all substitutes, variants and equivalents within the spirit of the invention and the scope of the invention as defined by the appended claims.

[0020] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. Those skilled in the art will appreciate that the present invention can be implemented without these specific details. In other examples, well-known methods, processes, components and circuits are not described in detail in order to highlight the subject matter of the present invention.

[0021] Figure 1FIG. 1 is a block diagram of a battery management system 100 according to an embodiment of the present invention. In one embodiment, the abnormality detection method using the battery management system 100 is as follows: first, a preset range of a theoretical time constant is determined when no abnormality occurs in the battery management system 100. Second, a measured time constant is determined. Finally, the measured time constant is compared with the preset range of the theoretical time constant to determine whether an abnormality occurs in the battery management system 100.

[0022] In one embodiment, the battery pack includes single cells CELL1, CELL2, ..., CELLn coupled in series. The battery management system 100 includes monitoring resistors RF0, RF1, ..., RFn, capacitors CF1, CF2, ..., CFn, balancing resistors RB1, RB2, ..., RBn, switches SW1, SW2, ..., SWn, a measuring unit 120 and a control unit 110.

[0023] The monitoring resistor RFj (j=1, 2, ..., n) is coupled to the positive electrode of the single cell CELLj or the negative electrode of the single cell CELL(j+1). The monitoring resistor RF1 is coupled to the negative electrode of the single cell CELLj. The monitoring resistor RF0 is coupled to the negative electrode of the single cell CELL1. The capacitor CFj (j=1, 2, ..., n) is connected between the monitoring resistor RF(j-1) and the monitoring resistor RFj. The monitoring resistors RF0, RF1, ..., RFn and the capacitors CF1, CF2, ..., CFn form an RC (Resistor-Capacitance) filter, which is used to filter out the high-frequency components in the voltage provided by each single cell, thereby eliminating unnecessary noise components.

[0024] The measuring unit 120 is coupled to the monitoring resistors RF0, RF1, ..., RFn, and is used to measure the voltage of each single cell in the battery pack. For example, the measuring unit 120 obtains the voltage V of the single cell CELL2 according to the difference between the voltage value on the node N2 and the voltage value on the node N1. CELL2 .

[0025] The balancing resistor RBj (j=1, 2, ..., n) is coupled in series with the switch SWj. The balancing resistor RBj and the switch SWj can be used together to balance the voltage of the single cell CELLj. For example, during the discharge process, when the voltage V CELL2 (e.g., 3V) and the voltage V of the single cell CELL1 CELL1 When the difference between the voltages (e.g., 3.4V) and the voltages (e.g., 3.4V) exceeds the balancing threshold (e.g., 0.1V), the switch SW1 is turned on and the switch SW2 is turned off, the single cell CELL1 discharges, and the discharge current flows through the balancing resistor RB1 until V CELL2 With V CELL1In the embodiment shown in the present invention, the balancing resistor RBj and the switch SWj can also be used together to detect abnormalities in the battery management system 100, and the specific content will be described in detail below.

[0026] The control unit includes a memory 111 and a microcontroller unit 112 (MCU). The pre-set program code is written into the MCU 112. The MCU 112 is configured with a timer 113 so that the MCU 112 runs the program code according to the time sequence set by the timer 113, thereby realizing the control function and the data processing function. The memory 111 is used to store data, such as theoretical time constants, etc. Specifically, the control unit 110 controls the switches SW1, SW2, ..., SWn to be turned on and off, and also controls the measuring unit 120 to measure the voltage value on the capacitor CFj, thereby obtaining the measured time constant. Since the theoretical time constant and the preset range of the theoretical time constant are both detected in the experimental stage (before the battery management system 100 is put into use), the memory in the control unit 110 also stores the theoretical time constant and the preset range of the theoretical time constant for comparison with the measured time constant. If the measured time constant is within the preset range of the theoretical time constant, the control unit 110 determines that the battery management system 100 is not abnormal, otherwise, the battery management system 100 is abnormal.

[0027] In addition, the embodiments of the present invention are not limited to Figure 1 The structure of the battery management system 100 in FIG. Figure 1 When the connection method of capacitor CFj in is changed, the method shown below is also applicable. Figure 1 The connection mode of the capacitor CFj in the battery management system 100 is changed to that one end of the capacitor CFj is connected to the monitoring resistor RFj, and the other end is connected to the ground of the battery management system 100.

[0028] Figure 2 The circuit diagram shown is a circuit diagram for detecting a single cell CELLj to determine whether an abnormality occurs in the battery management system 100 according to an embodiment of the present invention. The following will describe in detail two situations in which the battery management system 100 does not have an abnormality and has an abnormality. Figure 3 The figure shows a curve of the voltage on the capacitor CFj changing with time when the battery management system 100 according to one embodiment of the present invention is not abnormal, wherein the horizontal axis represents time, and the vertical axis represents the voltage value on the capacitor CFj. Figure 3 Will combine Figure 2 Make an introduction.

[0029] (1) No abnormality occurs in the battery management system 100

[0030] During the time period from t1 to t2 (where t1 to t2 is Figure 3 In the first time period T1 in the embodiment, the control unit 110 controls the switch SWj to be in the off state, and the single cell CELLj charges the capacitor CFj. In this embodiment, the capacitor CFj is fully charged at time t2. At time t2, the measuring unit 120 measures the voltage value on the capacitor CFj (the difference between the voltage value at the node N(j-1) and the voltage value at the node Nj) as the voltage value V of the single cell CELLj. CELLj .

[0031] During the time period from t2 to t3 (where t2 to t3 is Figure 3 In the second time period T2 in the embodiment, the control unit 110 controls the switch SWj to be in the on state, and the capacitor CFj discharges. In this embodiment, the capacitor CFj finishes discharging at time t3. That is, at time t3, the voltage value on the capacitor CFj reaches the stable value V E =V CELLj ·R RBj / (R RBj +R RFj +R RF(j-1) ), where R RF(j-1) Represents the resistance of the monitoring resistor RF(j-1), R RFj Indicates the resistance value of the monitoring resistor RFj, R RBj Indicates the resistance value of the monitoring resistor RBj.

[0032] During the time period from t3 to t4 (where t3 to t4 is Figure 3 In the third time period T3), the control unit 110 controls the switch SWj to be in the off state, and the single battery CELLj charges the capacitor CFj. In this embodiment, the capacitor CFj is fully charged at time t4. That is, the voltage value on the capacitor CFj increases from V E Restore to V CELLj .

[0033] In this embodiment, t is selected in the time period from t3 to t4. 31 Time, t 32 time, ..., t 3n At the moment, the measuring unit 120 respectively measures t 31 Time, t 32 time, ..., t 3n The multiple voltage values ​​V1, V2, ..., V on the capacitor CFj at the time n , thus obtaining (V1, Δt1), (V2, Δt2), ..., (V n , Δt n ), where Δt1 represents the time from time t3 to t 31 The length of time between moments, Δt2 represents the time from t3 to t32 The length of time between moments, ..., Δt n Indicates the time from t3 to t 3n In the time period from t3 to t4, the monitoring resistor RFj, RF(j-1) and capacitor CFj form an RC loop, and the theoretical time constant τ = Δt i / ln[K / (V CELLj -V i )], where K is a coefficient, i = 1, 2, ..., n. n , Δt n ) into the above equation, the coefficient K and the theoretical time constant τ can be calculated. In this embodiment, K = V CELLj -V E .

[0034] The preset range of the theoretical time constant τ is determined by the allowable error range. For example, if the theoretical time constant τ=A is calculated and the allowable error range is ±1 / 5, then the preset range of the theoretical time constant τ is A±A / 5. In addition, since each RC circuit has a different position in the battery management system 100, the theoretical time constant τ corresponding to each RC circuit is not equal.

[0035] (2) Abnormality occurs in the battery management system 100

[0036] The abnormality includes connection abnormality and component abnormality. If the two ends of the single cell CELLj are not properly connected to the battery management system 100 (e.g., disconnected, degraded, or not working satisfactorily), the connection between the battery management system 100 and the single cell CELLj is called a connection abnormality. If any of the capacitor CFj, the monitoring resistor RFj, and / or the monitoring resistor RF(j-1) does not operate normally (e.g., the capacitor CFj leaks, the monitoring resistor RFj and / or the monitoring resistor RF(j-1) increases / decreases), this situation is called a component abnormality.

[0037] For example, if the connection line between the battery management system 100 and the single battery CELLj is disconnected, the capacitor CFj cannot be charged during the time period from t3 to t4, and the voltage value on the capacitor CFj always maintains the voltage value at time t3. Therefore, in an ideal state, if a disconnection occurs, the voltage value on the capacitor CFj remains unchanged during the time period from t3 to t4.

[0038] For example, if the capacitor CFj leaks, the voltage on the capacitor CFj is less than V at time t3. E , and V cannot be restored at time t4 CELLj For example, if the resistance of the monitoring resistor RFj is RRFj Add and / or monitor the resistance R of resistor RF(j-1) RF(j-1) increases, the voltage on capacitor CFj can drop to V at time t3 E A voltage value near V at t4 cannot be restored. CELLj For example, if the resistance of the monitoring resistor RFj is R RFj Reduce and / or monitor the resistance value R of resistor RF(j-1) RF(j-1) decreases, the voltage on capacitor CFj can drop to V at time t3 E But before t4, it has recovered to V CELLj It can be seen that if one or more of the capacitor CFj, the monitoring resistor RF(j-1) and the monitoring resistor RFj in the battery management system 100 is abnormal, the change curve of the voltage value on the capacitor CFj during the time period from t3 to t4 will deviate from the change curve when the battery management system 100 is not abnormal.

[0039] In summary, when the battery management system 100 has the above-mentioned abnormality, during the time period from t3 to t4, the change curve of the voltage value on the capacitor CFj will always deviate from the change curve when the battery management system 100 has no abnormality ( Figure 3 The change curve of the voltage value on the capacitor CFj can be reflected by the time constant, that is, different time constants will result in different change curves of the voltage value on the capacitor CFj over time. Therefore, the present invention can determine whether the above abnormality occurs in the battery management system 100 by comparing the measured time constant with the preset range of the theoretical time constant. This is different from the traditional method of comparing the voltage value on the capacitor CFj with the disconnection threshold V CTO Compared with the comparative method, the method provided by the present invention can more accurately determine whether the battery management system 100 has the above-mentioned abnormality, so as to avoid misdiagnosis and thus improve the detection accuracy.

[0040] Figure 4 Shown is a flowchart 400 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Figure 4 Will combine Figure 2 and Figure 5 Make an introduction.

[0041] Step 401: When the battery management system 100 does not have the above-mentioned abnormality, the control unit 110 controls the switch SWj to be disconnected during the time period from t1 to t2, to be turned on during the time period from t2 to t3, and to be disconnected during the time period from t3 to t4. Wherein, t2-t1=T1, t3-t2=T2, t4-t3=T3.

[0042] Step 402: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t2 as the measured voltage value V of the single cell CELLj. CELLj .

[0043] Step 403: the control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at at least one time point in the time period from t3 to t4 as the measured capacitor voltage value, and measures the voltage value V of the single cell CELLj according to the at least one measured capacitor voltage value and the measured voltage value V of the single cell CELLj. CELLj Calculate and obtain the theoretical time constant. In this embodiment, the theoretical time constant corresponding to each RC loop is obtained by detection in the experimental stage. The method for calculating the theoretical time constant will be described in Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.11 The embodiments shown are described in detail.

[0044] Step 404 : Determine a preset range of the theoretical time constant according to the theoretical time constant. The theoretical time constant and the preset range of the theoretical time constant are both stored in the memory 111 of the control unit 110 .

[0045] Step 405: When abnormality detection is performed, the control unit 110 controls the switch SWj to be disconnected in the time period from t5 to t6, to be turned on in the time period from t6 to t7, and to be disconnected in the time period from t7 to t8. Among them, t6-t5=t2-t1=T1, t7-t6=t3-t2=T2, t8-t7=t4-t3=T3.

[0046] Step 406: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t6 as the measured voltage value V of the single cell CELLj. CELLj .

[0047] Step 407: the control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at at least one time point in the time period from t7 to t8 as the measured capacitor voltage value, and measures the voltage value V of the single cell CELLj according to the at least one measured capacitor voltage value and the measured voltage value V of the single cell CELLj. CELLj The method for calculating the measured time constant will be described in Figure 6 , Figure 7 , Figure 8 , Fig. 9 and Fig.11 The embodiments shown are described in detail.

[0048] In step 408 , the control unit 110 determines whether the measured time constant is within a preset range of the theoretical time constant. If so, step 408 proceeds to step 410 , otherwise, step 408 proceeds to step 409 .

[0049] In step 409 , the control unit 110 determines that an abnormality occurs in the battery management system 100 and generates an alarm to alert the user.

[0050] In step 410 , the control unit 110 determines that no abnormality occurs in the battery management system 100 .

[0051] In step 411, the control unit 110 determines whether all single cells have been detected. If yes, step 411 proceeds to step 413. Otherwise, step 411 proceeds to step 412.

[0052] In step 412 , the battery management system 100 starts detecting the next single battery, and the method returns to step 405 .

[0053] Step 413, detection ends.

[0054] The theoretical time constant is calculated in the same way as the measured time constant. Figure 6 Shown is a flowchart 600 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Figure 6 Will combine Figure 2 and Figure 5 Make an introduction.

[0055] Step 601, the control unit 110 controls the switch SWj to be disconnected in the time period from t5 to t6, to be turned on in the time period from t6 to t7, and to be disconnected in the time period from t7 to t8, wherein t6-t5=t2-t1=T1, t7-t6=t3-t2=T2, and t8-t7=t4-t3=T3.

[0056] Step 602: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t6 as the measured voltage value V of the single cell CELLj. CELLj .

[0057] Step 603: The control unit 110 controls the measuring unit 120 to measure the time interval t7 to t8. 71 Measure the voltage value V1 on the capacitor CFj at time t7 to obtain (V1, Δt1). Δt1 is the voltage between time t7 and t 71 The length of time between moments.

[0058] Step 604, according to the equation τ = Δt1 / ln[K / (V CELLj -V1)], the control unit 110 obtains the measured time constant τ. In this embodiment, K = VCELLj –V E .

[0059] Figure 7 Shown is a flowchart 700 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Figure 7 Will combine Figure 2 and Figure 5 The method is applied to a third time period T3 for a time period that is long enough to enable the control unit 110 to complete the calculation of multiple voltage values ​​at multiple time points. Figure 7 The method shown can be used to determine the measured time constant. Figure 6 The embodiment shown, Figure 7 The illustrated embodiment can reduce the problem of inaccurately measured time constants due to inaccurate calculation of the coefficient K, thereby improving detection accuracy.

[0060] Step 701, the control unit 110 controls the switch SWj to be disconnected in the time period from t5 to t6, to be turned on in the time period from t6 to t7, and to be disconnected in the time period from t7 to t8, wherein t6-t5=t2-t1=T1, t7-t6=t3-t2=T2, and t8-t7=t4-t3=T3.

[0061] Step 702: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t6 as the measured voltage value V of the single cell CELLj. CELLj .

[0062] Step 703: The control unit 110 controls the measuring unit 120 to measure the time interval t7 to t8. 71 Measure the voltage value V1 on the capacitor CFj at time t7 to obtain (V1, Δt1). Δt1 is the voltage between time t7 and t 71 The length of time between moments.

[0063] Step 704: the control unit 110 controls the measuring unit 120 to measure the time interval t7 to t8. 72 Measure the voltage value V2 on capacitor CFj at time t7 to obtain (V2, Δt2). Δt2 is the voltage between time t7 and t 72 The length of time between moments, Δt2≠Δt1.

[0064] Step 705, according to the equation τ = (Δt2-Δt1) / ln[(V1-V CELLj ) / (V2-V CELLj )], the control unit 110 obtains the measured time constant τ.

[0065] Figure 8Shown is a flowchart 800 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Figure 8 Will combine Figure 2 and Figure 5 The method is applied to a third time period T3 for a time period that is long enough to enable the control unit 110 to complete the calculation of multiple voltage values ​​at multiple time points. Figure 8 The method shown can be used to determine the measured time constant. Figure 7 The embodiment shown, Figure 8 The illustrated embodiment can further improve the accuracy of the measured time constant, thereby improving the detection accuracy.

[0066] Step 801: The control unit 110 controls the switch SWj to be disconnected during the time period from t5 to t6, to be turned on during the time period from t6 to t7, and to be disconnected during the time period from t7 to t8. Wherein, t6-t5=t2-t1=T1, t7-t6=t3-t2=T2, t8-t7=t4-t3=T3.

[0067] Step 802: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t6 as the measured voltage value V of the single cell CELLj. CELLj .

[0068] Step 803: The control unit 110 controls the measuring unit 120 to measure the time interval between t7 and t8. 71 Measure the voltage value V1 on the capacitor CFj at time t7 to obtain (V1, Δt1). Δt1 is the voltage between time t7 and t 71 The length of time between moments.

[0069] Step 804: the control unit 110 controls the measuring unit 120 to measure the time interval t7 to t8. 72 Measure the voltage value V2 on capacitor CFj at time t7 to obtain (V2, Δt2). Δt2 is the voltage between time t7 and t 72 The length of time between moments, Δt2≠Δt1.

[0070] Step 805, and so on, the control unit 110 controls the measuring unit 120 to measure the time period t7 to t8. 7n Measure the voltage value V on the capacitor CFj at all times n , to obtain (V n , Δt n ). Among them, Δt n From time t7 to t 7n The length of time between moments. In this embodiment, Δt1, Δt2, ..., Δt nIn other embodiments, Δt2≠Δt1, Δt3≠Δt2, ..., Δt (n-1) ≠Δt n , that is, the lengths of two adjacent time periods are not equal

[0071] Step 806, according to the equation τ1 = (Δt2 - Δt1) / ln[(V1 - V CELLj ) / (V2-V CELLj )], the control unit 110 obtains the first time constant τ1.

[0072] Step 807, according to the equation τ2 = (Δt3 - Δt2) / ln[(V2 - V CELLj ) / (V3-V CELLj )], the control unit 110 obtains the second time constant τ2.

[0073] Step 808, and so on, according to the equation τ(n-1)=(Δt n -Δt (n-1) ) / ln[(V (n-1) -V CELLj ) / (V n -V CELLj )], the control unit 110 obtains the (n-1)th time constant τ(n-1).

[0074] In step 809, the control unit 110 averages τ1, τ2, ..., τ(n-1) to obtain the measured time constant τ. In other embodiments, other calculation methods may be used to calculate τ1, τ2, ..., τ(n-1) to obtain the measured time constant τ.

[0075] Fig. 9 Shown is a flowchart 900 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Fig. 9 Will combine Figure 2 and Fig.10 Introduce. Figure 6 The embodiment shown, Fig. 9 The illustrated embodiment can reduce the problem of inaccurately measured time constants due to inaccurate calculation of the coefficient K, thereby improving detection accuracy.

[0076] Step 901: The control unit 110 controls the switch SWj to switch between the time periods t5 and t6, between the time periods t7 and t8, and between the time periods t9 and t10. 10 The circuit is disconnected during the time period from t6 to t7 and from t8 to t9. Among them, t6-t5=T1, t9-t8=t7-t6=T2, t 10 -t9=t8-t7=T3.

[0077] Step 902: The control unit 110 controls the measuring unit 120 to measure the voltage value on the capacitor CFj at time t6 as the measured voltage value V of the single cell CELLj. CELLj .

[0078] Step 903: The control unit 110 controls the measuring unit 120 to measure the time interval between t7 and t8. 71 Measure the voltage value V1 on the capacitor CFj at time t7 to obtain (V1, Δt1). Δt1 is the voltage between time t7 and t 71 The length of time between moments.

[0079] Step 904: the control unit 110 controls the measuring unit 120 to measure the 10 Time period t 72 At time t9, the voltage value V2 on the capacitor CFj is measured to obtain (V2, Δt2). Δt2 is the voltage between time t9 and t 72 The length of time between moments, Δt2≠Δt1.

[0080] Step 905, according to the equation τ = (Δt2-Δt1) / ln[(V1-V CELLj ) / (V2-V CELLj )], the control unit 110 obtains the measured time constant τ.

[0081] Fig.11 Shown is a flowchart 1100 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Fig.11 Reference Figure 2 and Fig.10 Introduce. Fig. 9 The embodiment shown, Fig.11 The illustrated embodiment can further improve the accuracy of the measured time constant, thereby improving the detection accuracy.

[0082] Step 1101: The control unit 110 controls the switch SWj to switch on in the time periods t5 to t6, t7 to t8, and t9 to t10. 10 Time period and t (5+2n) to (6+2n) Disconnected during the time period, during the time period from t6 to t7, during the time period from t8 to t9, and during t 10 to 11 The time period is on, n = 3, 4, .... Among them, t6-t5 = T1, t (5+2n) -t (4+2n) =t9-t8=t7-t6=T2, t (6+2n) -t (5+2n) =t 10 -t9=t8-t7=T3.

[0083] Step 1102: The control unit 110 controls the measuring unit 120 to measure the time interval t7 to t8. 71 Measure the voltage value V1 on the capacitor CFj at time t7 to obtain (V1, Δt1). Δt1 is the voltage between time t7 and t 71 The length of time between moments.

[0084] Step 1103: the control unit 110 controls the measuring unit 120 to measure the 10 Time period t 72 At time t9, the voltage value V2 on the capacitor CFj is measured to obtain (V2, Δt2). Δt2 is the voltage between time t9 and t 72 The length of time between moments, Δt2≠Δt1.

[0085] Step 1104, and so on, the control unit 110 controls the measuring unit 120 at t (5+2n) to (6+2n) Time period t 7n Measure the voltage value V on the capacitor CFj at all times n , to obtain (V n , Δt n ). Among them, Δt n t (5+2n) Time to t 7n The length of time between moments. In this embodiment, Δt1, Δt2, ..., Δt n are not equal to each other. In other embodiments, Δt n , ..., Δt2, Δt1 may be equal to two or more thereof.

[0086] Step 1105: According to (V1, Δt1), (V2, Δt2), ..., (V n , Δt n ), the control unit 110 uses the least square method to fit the change curve of the voltage value on the capacitor CFj, thereby obtaining the measured time constant. In other embodiments, other calculation methods can also be used to calculate (V1, Δt1), (V2, Δt2), ..., (V n , Δt n ) were fitted to obtain the measured time constant.

[0087] Fig.12 Shown is a flowchart 1200 of an abnormality detection method in a battery management system 100 according to an embodiment of the present invention. Fig.12 Will combine Figure 1 The method includes a first stage 1210 and a second stage 1220 .

[0088] The steps of the first stage 1210 are:

[0089] Step 1201 : Calculate the theoretical time constant corresponding to the first single cell CELL1 when no abnormality occurs in the battery management system 100 .

[0090] Step 1202: Determine a preset range of the theoretical time constant according to the theoretical time constant.

[0091] The steps of the second stage 1220 are:

[0092] Step 1203 , the control unit 110 controls the first switch SW1 to sequentially disconnect in the first time period T1 , connect in the second time period T2 , and disconnect in the third time period T3 .

[0093] Step 1204 : The control unit 110 controls the measuring unit 120 to measure the voltage value on the first capacitor CF1 at the end of the first time period T1 as the measured voltage value of the first single cell CELL1 .

[0094] In step 1205, the control unit 110 controls the measuring unit 120 to measure the voltage value on the first capacitor CF1 as the measured capacitor voltage value at at least one time point in the third time period T3, and obtains the measured time constant according to at least one measured capacitor voltage value and the measured voltage value of the first single cell CELL1.

[0095] Step 1206 , if the measured time constant exceeds the preset range of the theoretical time constant, the control unit 110 determines that an abnormality occurs in the battery management system 100 .

[0096] As mentioned above, the present invention discloses a method for detecting anomalies in a battery management system. The method uses the change curve (time constant) of the voltage value on the capacitor as the comparison object, and can accurately detect various anomalies occurring in the battery management system, thereby improving the detection accuracy.

[0097] The above specific implementation methods and drawings are only common embodiments of the present invention. Obviously, various additions, modifications and substitutions can be made without departing from the spirit and scope of the present invention defined by the claims. It should be understood by those skilled in the art that the present invention can be varied in form, structure, layout, proportion, material, element, assembly and other aspects according to specific environment and working requirements in practical applications without departing from the invention criteria. Therefore, the embodiments disclosed herein are only for illustration and not limitation, and the scope of the present invention is defined by the attached claims and their legal equivalents, and is not limited to the previous description.

Claims

1. A method for detecting anomalies in a battery management system, wherein: The battery management system includes a measuring unit, a control unit, a first monitoring resistor, a second monitoring resistor, a first capacitor, a first switch and a first balancing resistor, wherein a first single cell in a battery pack is coupled to the first monitoring resistor, the second monitoring resistor, the first capacitor, the first switch and the first balancing resistor, and the method includes: Calculating a theoretical time constant corresponding to the first single battery when no abnormality occurs in the battery management system; Determining a preset range of the theoretical time constant according to the theoretical time constant; and Perform the following steps to detect the first single battery to determine whether the battery management system is abnormal: The control unit controls the first switch to sequentially disconnect for a first time period, connect for a second time period, and disconnect for a third time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured voltage value of the first single battery at the end of the first time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and obtains a measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery; and If the measured time constant exceeds the preset range of the theoretical time constant, the control unit determines that an abnormality occurs in the battery management system. Wherein, when the abnormality does not occur in the battery management system, the step of calculating the theoretical time constant corresponding to the first single battery includes: The control unit controls the first switch to sequentially disconnect the fourth time period, connect the fifth time period, and disconnect the sixth time period, wherein the length of the fourth time period is equal to the length of the first time period, the length of the fifth time period is equal to the length of the second time period, and the length of the sixth time period is equal to the length of the third time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured second voltage value of the first single battery at the end of the fourth time period; and The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured second capacitor voltage value at at least one time point within the sixth time period, and obtains the theoretical time constant according to at least one of the measured second capacitor voltage values ​​and the measured second voltage value of the first single cell.

2. The method according to claim 1, characterized in that The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; According to the equation τ=Δt1 / ln[K / (V CELL1 -–V1)], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell, and K is a coefficient.

3. The method according to claim 2, characterized in that K=V CELL1 -V E , where V E is the voltage value on the first capacitor measured at the end of the second time period.

4. The method according to claim 1, characterized in that: The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the third time period, wherein the time length from the start of the third time period to the second time point is Δt2, and the second time point is different from the first time point; and According to the equation τ = (Δt2-Δt1) / ln[(V1-V CELL1 ) / (V2-V CELL1 )], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell.

5. The method according to claim 1, characterized in that The method further comprises: The control unit controls the first switch to sequentially turn on a fourth time period and turn off a fifth time period, wherein the length of the fourth time period is equal to the length of the second time period, and the length of the fifth time period is equal to the length of the third time period; The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the fifth time period, wherein the time length from the start time of the fifth time period to the second time point is Δt2, wherein Δt1≠Δt2; and According to the equation τ = (Δt2-Δt1) / ln[(V1-V CELL1 ) / (V2-V CELL1 )], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell.

6. The method according to claim 1, characterized in that The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the third time period, wherein the time length from the start time of the third time period to the second time point is Δt2, and the second time point is different from the first time point; The measuring unit measures a third voltage value V3 on the first capacitor at a third time point within the third time period, wherein the time length from the start time of the third time period to the third time point is Δt3, and the third time point is different from the first time point and the second time point; According to the equation τ1 = (Δt2 - Δt1) / ln[(V1 - V CELL1 ) / (V2-V CELL1 )], the control unit obtains a first time constant τ1, where V CELL1 is the measured voltage value of the first monomer cell; According to the equation τ2 = (Δt3 - - Δt2) / ln [(V2 - V CELL1 ) / (V3-V CELL1 )], the control unit obtains a second time constant τ2; and The control unit obtains the measured time constant according to the first time constant and the second time constant.

7. The method according to claim 6, characterized in that The step of obtaining the measured time constant by the control unit according to the first time constant and the second time constant comprises: The control unit averages the first time constant and the second time constant to obtain the measured time constant.

8. The method according to claim 6, characterized in that The method further comprises: The control unit processes (V1, Δt1), (V2, Δt2), and (V3, Δt3) using a least square method to obtain the measured time constant.

9. The method according to claim 1, characterized in that: The method further comprises: The control unit controls the first switch to sequentially turn on the fourth time period, turn off the fifth time period, turn on the sixth time period, and turn off the seventh time period; wherein the length of the fourth time period and the length of the sixth time period are both equal to the length of the second time period, and the length of the fifth time period and the length of the seventh time period are both equal to the length of the third time period; The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the fifth time period, wherein the time length from the start time of the fifth time period to the second time point is Δt2; The measuring unit measures a third voltage value V3 on the first capacitor at a third time point within the seventh time period, wherein the time length from the start time of the seventh time period to the third time point is Δt3, wherein Δt1≠Δt2, Δt2≠Δt3; According to the equation τ1 = (Δt2 - Δt1) / ln[(V1 - V CELL1 ) / (V2-V CELL1 )], the control unit obtains a first time constant τ1, where V CELL1 is the measured voltage value of the first monomer cell; According to the equation τ2 = (Δt3 - Δt2) / ln[(V2 - V CELL1 ) / (V3-V CELL1 )], the control unit obtains a second time constant τ2; and The control unit obtains the measured time constant according to the first time constant and the second time constant.

10. A battery management system, characterized in that: include: Measuring unit; a control unit coupled to the measuring unit; a first monitoring resistor coupled to the measuring unit; a second monitoring resistor coupled to the measuring unit; a first capacitor coupled to the measuring unit; a first switch coupled to the measuring unit; as well as A first balancing resistor coupled to the measuring unit, wherein a first single cell in the battery pack is coupled to the first monitoring resistor, the second monitoring resistor, the first capacitor, the first switch and the first balancing resistor; The battery management system is configured to perform a method comprising the following steps: Calculating a theoretical time constant corresponding to the first single battery when no abnormality occurs in the battery management system; Determining a preset range of the theoretical time constant according to the theoretical time constant; The control unit controls the first switch to sequentially disconnect for a first time period, connect for a second time period, and disconnect for a third time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured voltage value of the first single battery at the end of the first time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and obtains a measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery; and If the measured time constant exceeds the preset range of the theoretical time constant, the control unit determines that an abnormality occurs in the battery management system. Wherein, when the abnormality does not occur in the battery management system, the step of calculating the theoretical time constant corresponding to the first single battery includes: The control unit controls the first switch to sequentially disconnect the fourth time period, connect the fifth time period, and disconnect the sixth time period, wherein the length of the fourth time period is equal to the length of the first time period, the length of the fifth time period is equal to the length of the second time period, and the length of the sixth time period is equal to the length of the third time period; The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured second voltage value of the first single battery at the end of the fourth time period; and The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured second capacitor voltage value at at least one time point within the sixth time period, and obtains the theoretical time constant according to at least one of the measured second capacitor voltage values ​​and the measured second voltage value of the first single cell.

11. The system according to claim 10, characterized in that The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; According to the equation τ=Δt1 / ln[K / (V CELL1 -–V1)], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell, and K is a coefficient.

12. The system according to claim 11, characterized in that K=V CELL1 -V E , where V E is the voltage value on the first capacitor measured at the end of the second time period.

13. The system according to claim 10, characterized in that The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the third time period, wherein the time length from the start of the third time period to the second time point is Δt2, and the second time point is different from the first time point; and According to the equation τ = (Δt2-Δt1) / ln[(V1-V CELL1 ) / (V2-V CELL1 )], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell.

14. The system according to claim 10, characterized in that The battery management system is further configured to perform the following steps: The control unit controls the first switch to sequentially turn on a fourth time period and turn off a fifth time period, wherein the length of the fourth time period is equal to the length of the second time period, and the length of the fifth time period is equal to the length of the third time period; The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the fifth time period, wherein the time length from the start time of the fifth time period to the second time point is Δt2, wherein Δt1≠Δt2; and According to the equation τ = (Δt2-Δt1) / ln[(V1-V CELL1 ) / (V2-V CELL1 )], the control unit obtains the measured time constant, wherein τ is the measured time constant, V CELL1 is the measured voltage value of the first monomer cell.

15. The system according to claim 10, characterized in that The control unit controls the measuring unit to measure the voltage value on the first capacitor as the measured capacitor voltage value at at least one time point within the third time period, and the step of obtaining the measured time constant according to at least one of the measured capacitor voltage values ​​and the measured voltage value of the first single battery includes: The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the third time period, wherein the time length from the start time of the third time period to the second time point is Δt2, and the second time point is different from the first time point; The measuring unit measures a third voltage value V3 on the first capacitor at a third time point within the third time period, wherein the time length from the start time of the third time period to the third time point is Δt3, and the third time point is different from the first time point and the second time point; According to the equation τ1 = (Δt2 - Δt1) / ln[(V1 - V CELL1 ) / (V2-V CELL1 )], the control unit obtains a first time constant τ1, where V CELL1 is the measured voltage value of the first monomer cell; According to the equation τ2 = (Δt3 - - Δt2) / ln [(V2 - V CELL1 ) / (V3-V CELL1 )], the control unit obtains a second time constant τ2; and The control unit obtains the measured time constant according to the first time constant and the second time constant.

16. The system according to claim 15, characterized in that The step of obtaining the measured time constant by the control unit according to the first time constant and the second time constant comprises: The control unit averages the first time constant and the second time constant to obtain the measured time constant.

17. The system according to claim 15, characterized in that The battery management system is further configured to perform the following steps: The control unit processes (V1, Δt1), (V2, Δt2), and (V3, Δt3) using a least square method to obtain the measured time constant.

18. The system according to claim 10, characterized in that The battery management system is further configured to perform the following steps: The control unit controls the first switch to sequentially turn on the fourth time period, turn off the fifth time period, turn on the sixth time period, and turn off the seventh time period; wherein the length of the fourth time period and the length of the sixth time period are both equal to the length of the second time period, and the length of the fifth time period and the length of the seventh time period are both equal to the length of the third time period; The measuring unit measures a first voltage value V1 on the first capacitor at a first time point within the third time period, wherein the time length from the start time of the third time period to the first time point is Δt1; The measuring unit measures a second voltage value V2 on the first capacitor at a second time point within the fifth time period, wherein the time length from the start time of the fifth time period to the second time point is Δt2; The measuring unit measures a third voltage value V3 on the first capacitor at a third time point within the seventh time period, wherein the time length from the start time of the seventh time period to the third time point is Δt3, wherein Δt1≠Δt2, Δt2≠Δt3; According to the equation τ1 = (Δt2 - Δt1) / ln[(V1 - V CELL1 ) / (V2-V CELL1 )], the control unit obtains a first time constant τ1, where V CELL1 is the measured voltage value of the first monomer cell; According to the equation τ2 = (Δt3 - Δt2) / ln[(V2 - V CELL1 ) / (V3-V CELL1 )], the control unit obtains a second time constant τ2; and The control unit obtains the measured time constant according to the first time constant and the second time constant.

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