A current detection circuit and battery management system

Abstract

This application relates to a current detection circuit and battery management system, belonging to the field of battery management technology. The current detection circuit includes a current sampling module, a first operational amplifier module, a second operational amplifier module, and a processing module. The first operational amplifier module and the second operational amplifier module are connected in parallel at both ends of the current sampling module. The processing module is connected to the output of the first operational amplifier module and the output of the second operational amplifier module, and is used to determine the current flowing through the current sampling module based on the output voltages of the first operational amplifier module and the second operational amplifier module. Using this application, the influence of the external environment on current detection can be reduced, ensuring the success rate of battery management.

Description

Technical Field

[0001] The present application relates to the technical field of battery management, and in particular to a current detection circuit and a battery management system. Background Art

[0002] A battery management system (BMS) is a safety protection system used to assist the normal operation of batteries. It continuously monitors the battery's usage status and determines battery attributes such as remaining power, current input and output, in order to reduce the probability of battery failure and extend the battery's service life.

[0003] The battery's state of charge (SOC) is a key parameter in a battery management system (BMS), and SOC estimation is also a crucial step in battery management. The ampere-hour integration method is a common method for SOC estimation. During the estimation process, the BMS continuously monitors the battery's output current and integrates the measured current over time to calculate the battery's power output, thereby estimating the battery's SOC.

[0004] In the process of implementing this application, the inventors discovered that the above technology has at least the following problems:

[0005] In battery management tasks like estimating the state of charge (SOC) described above, inaccurate current detection can lead to cumulative errors over time, significantly impacting the success rate of battery management. Therefore, a method is urgently needed to improve the accuracy of current detection to ensure successful battery management. Summary of the Invention

[0006] In order to reduce the impact of the external environment on current detection, the present invention provides a current detection circuit and a battery management system. The technical solution is as follows:

[0007] In a first aspect, an embodiment of the present application provides a current detection circuit, the current detection circuit comprising a current sampling module, a first operational amplifier module, a second operational amplifier module, and a processing module, wherein the first operational amplifier module and the second operational amplifier module are connected in parallel at both ends of the current sampling module;

[0008] The first operational amplifier module includes a first resistor R1, a second resistor R2 and a first operational amplifier Y1, wherein the non-inverting input terminal of Y1 is connected to the input terminal of the current sampling module, R1 and R2 are connected in series between the output terminal of Y1 and the output terminal of the current sampling module, and the inverting input terminal of Y1 is connected to the connection point of R1 and R2;

[0009] The second operational amplifier module includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a second operational amplifier Y2, wherein R5 and R6 are connected in series between a control power supply and an output terminal of the current sampling module, a non-inverting input terminal of Y2 is connected to a connection point between R5 and R6, R3 and R4 are connected in series between the output terminal of Y2 and an input terminal of the current sampling module, and an inverting input terminal of Y2 is connected to a connection point between R3 and R4;

[0010] The processing module is connected to the output end of Y1 and the output end of Y2, and is used to determine the current flowing through the current sampling module according to the output voltages of Y1 and Y2.

[0011] By adopting the above technical solution, Y1 and Y2 are selected as operational amplifiers of the same model and batch. When the external environment affects the operational amplifier, there will be an uncontrollable deviation in the voltage difference between its non-inverting input and inverting input. According to the above structure, the non-inverting input and inverting input of Y1 and Y2 are alternately connected to the two ends of the current sampling module. The processing module then calculates the current based on the voltage signals output by Y1 and Y2. By setting the parameter values ​​of each component in the current detection circuit, the deviations in the voltage signals output by Y1 and Y2 can be offset by each other, thereby reducing the impact of the external environment on current detection and ensuring the success rate of battery management to a certain extent.

[0012] Optionally, the ratio of the resistance values ​​of R1 to R2 is equal to the ratio of the resistance values ​​of R4 to R3.

[0013] By adopting the above technical solution, V 1O -V 2O V △ Eliminate, thereby reducing the impact of the external environment on the current detection results.

[0014] Optionally, the first operational amplifier module further includes a seventh resistor R7 and an eighth resistor R8, wherein R7 is connected in series between the input end of the current sampling module and the non-inverting input end of Y1, and R8 is connected in series between the control power supply and the non-inverting input end of Y1.

[0015] By adopting the above technical solution, it is possible to avoid the influence on the current detection process caused by the voltage at the input end of the current sampling module being too low.

[0016] Optionally, the resistance ratio of R3 to R4 is equal to the resistance ratio of R2 to R1; the resistance ratio of R7 to R8 is equal to the resistance ratio of R5 to R6.

[0017] By adopting the above technical solution, the influence of the external environment on the current detection result can be reduced, and the difference in the output voltages between Y1 and Y2 can be calculated more easily, thereby improving the efficiency of current detection.

[0018] Optionally, the current detection circuit also includes a third operational amplifier module, which includes a ninth resistor R9, a tenth resistor R10 and a third operational amplifier Y3, wherein R9 and R10 are connected in series between the control power supply and the ground line, and the connection point of R9 and R10 is connected to the non-inverting input terminal of Y3, the inverting input terminal of Y3, the output terminal of Y3, the power terminal of R8 and the power terminal of R6 are connected.

[0019] By adopting the above technical solution, a stable control power supply voltage can be provided to Y1 and Y2 through the newly added third operational amplifier module 5 .

[0020] Optionally, the input end of the current sampling module is connected to the power supply, and the output end is connected to the power system; or, the input end of the current sampling module is connected to the power system, and the output end is grounded.

[0021] By adopting the above technical solution, the interference of the ground level on the current detection result can be reduced, and at the same time, whether the power system is short-circuited can be monitored; or a lower-cost ordinary operational amplifier can be selected to save the cost of the power management system.

[0022] Optionally, the current sampling module is a current sampling resistor.

[0023] Optionally, the processing module is used to calculate the difference between the output voltages of Y1 and Y2 in real time, and determine the current value flowing through the current sampling module based on the difference and the parameter values ​​of each component in the current detection circuit.

[0024] By adopting the above technical solution, the processing module can reduce the impact of the external environment on the current detection result and ensure the accuracy of current detection.

[0025] Optionally, the processing module is used to determine at least one target power consumption period in historical power consumption periods that is similar to the current change curve of the current power consumption period, and calculate the total power consumption of the current power consumption period based on the target power consumption period and the current change curve of the current power consumption period.

[0026] By adopting the above technical solution, the accuracy of estimating total power consumption can be improved through the current detection results of historical power consumption periods.

[0027] In a second aspect, an embodiment of the present application further provides a battery management system, which is configured with the current detection circuit as described in the first aspect, and is used to detect the output current of the battery through the current detection circuit.

[0028] In summary, this application has the following beneficial effects:

[0029] By adopting the above technical solution, two operational amplifiers are connected in parallel with the current sampling module, with their input terminals connected in opposite directions to the current sampling module. A processing module is configured to determine the current flowing through the current sampling module based on the output voltages of the two operational amplifiers. This allows the processing module to offset the offsets caused by the external environment's simultaneous impact on the two operational amplifiers when calculating the current, thereby improving the accuracy of current detection and ensuring the success rate of battery management. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the circuit structure of a current detection circuit in an embodiment of the present application;

[0031] Figure 2 Schematic diagram of the circuit structure of a current detection circuit in an embodiment of the present application;

[0032] Figure 3 Schematic diagram of the circuit structure of a current detection circuit in an embodiment of the present application;

[0033] Description of reference numerals: 1. current sampling module; 2. first operational amplifier module;

[0034] 3. Second op amp module; 4. Processing module

[0035] 5. The third op amp module. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-3 It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0037] The embodiment of the present application provides a current detection circuit, which can be deployed in a battery management system to detect the output current of the battery in real time. Figure 1As shown, the current detection circuit generally includes a current sampling module 1, a first operational amplifier module 2, a second operational amplifier module 3, and a processing module 4. The current sampling module 1 can be deployed in the working circuit of the battery to collect the battery's output current. Specifically, a current sampling resistor connected in series with the battery's working circuit can be selected. The first operational amplifier module 2 and the second operational amplifier module 3 can be connected in parallel with the current sampling module 1 to obtain the current signal from the current sampling module 1 and convert the current signal into a voltage signal for output. The processing module 4 can receive the voltage signal output by the first operational amplifier module 2 and the second operational amplifier module 3 and convert the voltage signal into a current signal, thereby completing the battery output current detection process.

[0038] Specifically, the first operational amplifier module 2 can be composed of a first resistor R1, a second resistor R2 and a first operational amplifier Y1, wherein the power supply end of Y1 is connected to the control power supply, the ground end of Y1 is grounded, the non-inverting input end of Y1 is connected to the input end of the current sampling module 1, one end of R1 is connected to the output end of the current sampling module 1, and the other end is connected to the inverting input end of Y1 and one end of R2, and the other end of R2 is connected to the output end of Y1.

[0039] The second operational amplifier module 3 may include a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a second operational amplifier Y2, wherein a power supply end of Y2 is connected to a control power supply, a ground end of Y2 is grounded, one end of R6 is connected to a control power supply VDD, and the other end is connected to one end of R5 and a non-inverting input end of Y2, the other end of R5 is connected to the output end of the current sampling module 1, a connection point between R5 and R6 is connected to the non-inverting input end of Y2, the output end of Y2 is connected to one end of R3, the other end of R3 is connected to the inverting input end of Y2 and one end of R4, and the other end of R4 is connected to the input end of the current sampling module 1.

[0040] The processing module is connected to the output end of Y1 and the output end of Y2, and can be used to determine the current flowing through the current sampling module 1 according to the output voltages of Y1 and Y2.

[0041] In this way, Y1 and Y2 are selected as operational amplifiers of the same model and batch. When the external environment affects the operational amplifier, there will be an uncontrollable deviation in the voltage difference between its non-inverting input and inverting input. According to the above structure, the non-inverting input and inverting input of Y1 and Y2 are alternately connected to the two ends of the current sampling module. The processing module 4 then calculates the current based on the voltage signals output by Y1 and Y2. By setting the parameter values ​​of each component in the current detection circuit, the deviations in the voltage signals output by Y1 and Y2 can be offset by each other, thereby reducing the impact of the external environment on current detection and ensuring the success rate of battery management to a certain extent.

[0042] Based on the structure of the first operational amplifier module 2 and the second operational amplifier module 3, the output voltage of Y1, the voltage of the non-inverting input terminal, and the voltage of the inverting input terminal are set to V1o, V1+, and V1-, respectively; the output voltage of Y2 is set to V2o, V2+, and V2-, respectively; the input and output voltages of the current sampling module 1 are V0+ and V0-, respectively; the control power supply voltage is VDD; Y1 and Y2 are affected by the external environment; the voltage difference between the non-inverting input terminal and the inverting input terminal is V △ , then we can have:

[0043]

[0044]

[0045] Further calculations yield:

[0046]

[0047]

[0048] It can be seen that when the resistance ratio of R1 to R2 is equal to the resistance ratio of R4 to R3, V 1O -V 2O V △ Eliminate, thereby reducing the impact of the external environment on the current detection results.

[0049] Reference Figure 3 To prevent the voltage at the input of current sampling module 1 from being too low, thereby affecting the current detection process, an external voltage can be introduced to the non-inverting input of first op amp module 2, referring to the structure of second op amp module 3. Specifically, first op amp module 2 may further include a seventh resistor R7 and an eighth resistor R8, wherein R7 is connected in series between the input of current sampling module 1 and the non-inverting input of Y1, and R8 is connected in series between the control power supply VDD and the non-inverting input of Y1.

[0050] Based on the structure of the first operational amplifier module 2, the output voltage of Y1 is set to V1o, V1+, and V1-, respectively. The output voltage of Y2 is set to V2o, V2+, and V2-, respectively. The input and output voltages of the current sampling module 1 are V0+ and V0-, respectively. The control power supply voltage is VDD. Y1 and Y2 are affected by the external environment. The voltage difference between the in-phase input and the inverting input is V △ , then we can have:

[0051]

[0052] Further calculations yield:

[0053]

[0054] It can be seen that when the resistance ratio of R1 to R2 is equal to the resistance ratio of R4 to R3, V 1O -V 2O V △ Eliminate, thereby reducing the impact of the external environment on the current detection results. And when the resistance ratio of R7 to R8 is equal to the resistance ratio of R5 to R6, it is easier to calculate the output voltage difference between Y1 and Y2, thereby improving the efficiency of current detection.

[0055] Reference Figure 3 , you can Figure 3 A third operational amplifier module 5 is newly added to the structure for providing a stable control power supply voltage to Y1 and Y2. Specifically, the third operational amplifier module 5 may include a ninth resistor R9, a tenth resistor R10, and a third operational amplifier Y3. The power supply terminal of Y3 is connected to the control power supply, the ground terminal of Y2 is grounded, R9 and R10 are connected in series between the control power supply and the ground line, the connection point of R9 and R10 is connected to the non-inverting input terminal of Y3, the inverting input terminal of Y3, the output terminal of Y3, the power terminal of R8, and the power terminal of R6. Here, the power terminals of R8 and R6 may be Figure 3 R8 and R6 are connected to one end of the control power supply.

[0056] Based on the above structure, we can have:

[0057]

[0058]

[0059] It can be seen that when the resistance ratio of R1 to R2 is equal to the resistance ratio of R4 to R3, and when the resistance ratio of R7 to R8 is equal to the resistance ratio of R5 to R6, V 1O - V 2O V △ Eliminate, thereby reducing the impact of the external environment on the current detection results.

[0060] Optionally, the current sampling module 1 can be selectively connected between the power supply and the power system, or between the power system and the ground line, depending on actual needs. Specifically, if higher current detection accuracy is required, the input end of the current sampling module 1 can be connected to the power supply, and the output end can be connected to the power system. In this way, on the one hand, the interference of the ground level on the current detection result can be reduced, and on the other hand, whether the power system is short-circuited can be monitored at the same time. If a certain degree of current detection deviation is acceptable, the input end of the current sampling module 1 can be connected to the power system, and the output end can be grounded. In this way, Y1 and Y2 can use lower-cost ordinary operational amplifiers.

[0061] Optionally, the processing module 4 can be used to calculate the difference between the output voltages of Y1 and Y2 in real time, and determine the current value flowing through the current sampling module 1 based on the difference and the parameter values ​​of each component in the current detection circuit.

[0062] In practice, processing module 4 can continuously obtain the output voltages of Y1 and Y2 and calculate the difference between the output voltages of Y1 and Y2 in real time. Furthermore, processing module 4 can be pre-set with parameter values ​​for each component in the current detection circuit. The processing module can use these parameter values ​​and the difference to determine the current value flowing through current sampling module 1 at each moment, thereby implementing current detection processing.

[0063] Optionally, the processing module 4 can combine the real-time current detection results and the historical current detection results to estimate the power consumption. Accordingly, the processing module 4 can be used to determine at least one target power consumption period in the historical power consumption period that is similar to the current change curve of the current power consumption period, and calculate the total power consumption of the current power consumption period based on the current change curve of the target power consumption period and the current power consumption period.

[0064] A power consumption period may be the time period during which the power consumption system is turned on and off.

[0065] In practice, while detecting current, processing module 4 can record the current detection results over time and generate a current variation curve corresponding to each power usage period, using power usage period as a unit. Thus, when generating the current variation curve for the current power usage period, processing module 4 can compare this current variation curve with the current variation curves corresponding to historical power usage periods. If there is at least one target power usage period with a current variation curve similar to the current power usage period, processing module 4 can calculate the total power consumption for the current power usage period based on the current variation curves for the target power usage period and the current power usage period.

[0066] Furthermore, one charge and discharge cycle can be defined as one power cycle. For each power cycle, processing module 4 can determine multiple power usage periods corresponding to the power cycle and adjust the calculation process for the total power usage of each power usage period based on the charge power corresponding to the power cycle and the total power usage of the multiple power usage periods. For example, if the charge power corresponding to multiple power cycles is approximately 1.1 times the total power usage, a gain factor can be added to the calculation of the total power usage.

[0067] By adopting the above technical solution, two operational amplifiers are connected in parallel with the current sampling module 1, with their input terminals connected to the current sampling module 1 in opposite directions. A processing module is configured to determine the current flowing through the current sampling module 1 based on the output voltages of the two operational amplifiers. This allows the external environment to simultaneously affect the two operational amplifiers, causing numerical offsets. When calculating the current, the processing module 4 can offset these offsets, thereby improving the accuracy of current detection and ensuring the success rate of battery management.

[0068] The present application also provides a battery management system, which is configured as follows: Figure 1-Figure 3 The current detection circuit shown is used by the battery management system to detect the output current of the battery.

[0069] The above are all preferred embodiments of the present application and are not intended to limit the scope of protection of this application. Unless otherwise stated, any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features. In other words, unless otherwise stated, each feature is merely an example of a series of equivalent or similar features.

Claims

1. A current detection circuit, characterized in that: The current detection circuit includes a current sampling module, a first operational amplifier module, a second operational amplifier module, a third operational amplifier module and a processing module, wherein the first operational amplifier module and the second operational amplifier module are connected in parallel at both ends of the current sampling module; The first operational amplifier module includes a first resistor R1, a second resistor R2 and a first operational amplifier Y1, wherein the non-inverting input terminal of Y1 is connected to the input terminal of the current sampling module, R1 and R2 are connected in series between the output terminal of Y1 and the output terminal of the current sampling module, and the inverting input terminal of Y1 is connected to the connection point of R1 and R2; The second operational amplifier module includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a second operational amplifier Y2, wherein R5 and R6 are connected in series between the control power supply and the output end of the current sampling module, the non-inverting input end of Y2 is connected to the connection point of R5 and R6, the R3 and R4 are connected in series between the output end of Y2 and the input end of the current sampling module, and the inverting input end of Y2 is connected to the connection point of R3 and R4; The first operational amplifier module further includes a seventh resistor R7 and an eighth resistor R8, wherein R7 is connected in series between the input terminal of the current sampling module and the non-inverting input terminal of Y1, and R8 is connected in series between the control power supply and the non-inverting input terminal of Y1; The third operational amplifier module includes a ninth resistor R9, a tenth resistor R10, and a third operational amplifier Y3, wherein R9 and R10 are connected in series between the control power supply and the ground line, the connection point of R9 and R10 is connected to the non-inverting input terminal of Y3, the inverting input terminal of Y3, the output terminal of Y3, the power terminal of R8, and the power terminal of R6 are connected; The processing module is connected to the output end of the Y1 and the output end of the Y2, and is used to determine the current flowing through the current sampling module according to the output voltages of the Y1 and the Y2, and calculate the difference between the output voltages of the Y1 and the Y2 in real time, and determine the current value flowing through the current sampling module according to the difference and the parameter values ​​of each component in the current detection circuit; The ratio of the resistance values ​​of R1 to R2 is equal to the ratio of the resistance values ​​of R4 to R3; The input end of the current sampling module is connected to the power supply, and the output end is connected to the power system; or the input end of the current sampling module is connected to the power system, and the output end is grounded.

2. The circuit according to claim 1, wherein: The ratio of the resistance values ​​of R7 to R8 is equal to the ratio of the resistance values ​​of R5 to R6.

3. The circuit according to claim 1, wherein: The current sampling module is a current sampling resistor.

4. The circuit according to claim 1, wherein: The processing module is used to determine at least one target power consumption period in historical power consumption periods that has a current variation curve similar to that of the current power consumption period, and calculate the total power consumption of the current power consumption period based on the target power consumption period and the current variation curve of the current power consumption period.

5. A battery management system, characterized in that: The battery management system is configured with the current detection circuit according to any one of claims 1 to 4, and the battery management system is used to detect the output current of the battery through the current detection circuit.

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