A shunt current collection structure and a battery management system
By combining a single shunt with redundant acquisition circuitry and an analog front-end chip, the high cost and complex circuitry of existing battery management systems are solved, achieving high functional safety level current measurement, reducing system cost and optimizing space utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HEFEI GUOXUAN HIGH TECH POWER ENERGY
- Filing Date
- 2025-06-26
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technical solutions for measuring automotive-grade power battery current have drawbacks, including high system cost, complex hardware circuitry, numerous components, increased wiring harnesses, and space occupation, making it difficult to meet ASIL C functional safety level requirements.
The design employs a single shunt combined with redundant acquisition circuits, analog front-end chips, and microcontroller units. Redundant acquisition and transmission of current signals are achieved through redundant current acquisition circuits and analog front-end chips with different safety levels, optimizing the circuit structure to meet high functional safety levels.
While meeting ASIL C functional safety standards, the system cost was reduced, the hardware circuitry was simplified, the number of components and space occupation were reduced, and the battery space utilization was optimized.
Smart Images
Figure CN224456870U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of current acquisition system, and specifically relates to a shunt current acquisition structure and battery management system. Background Technology
[0002] With the rapid development of the new energy vehicle industry, cost optimization of battery management systems has increasingly become a key focus of industry research and development. The principle of a shunt is based on the physical characteristic that a voltage is generated at the terminal when direct current flows through a resistor. Common types of shunts on the market include fixed-value shunts and precision alloy resistors. Currently, the current measurement of automotive-grade power batteries must meet functional safety requirements of at least ASIL C. Existing technical solutions typically employ either a single shunt paired with a Hall current sensor or a dual shunt approach to achieve ASIL C functional safety.
[0003] 1. The core difficulty of the existing technical solutions lies in the fact that both the heterogeneous solution combining Hall sensors and shunts and the homogeneous solution with dual shunts will significantly increase the system cost.
[0004] 2. Existing solutions all lead to an increase in the number of circuit components, making the hardware circuit more complex and increasing the system failure rate.
[0005] 3. Using either a dual shunt or a shunt combined with a Hall sensor increases the wiring harness and the number of potential failure points. Furthermore, existing solutions occupy internal space within the battery pack, hindering the efficient use of battery space. Utility Model Content
[0006] To address the problems in the background art, this utility model proposes a shunt current acquisition structure and a battery management system.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A shunt current acquisition structure includes a shunt, a redundant acquisition circuit, an analog front-end chip, and a microcontroller unit;
[0009] The splitter is connected to the redundant acquisition circuit;
[0010] The redundant acquisition circuits are connected to the analog front-end chip based on different security levels;
[0011] The analog front-end chip is connected to the microcontroller unit.
[0012] Preferably, the analog front-end chip includes a current I / O interface, an analog acquisition port, a first analog-to-digital converter, and a second analog-to-digital converter;
[0013] The current I / O interface and the analog acquisition port are connected to the redundant circuit based on different security levels;
[0014] The first analog-to-digital converter is connected to the current I / O interface, and the second analog-to-digital converter is connected to the analog acquisition port.
[0015] Preferably, the analog front-end chip conforms to the safety level ASIL C.
[0016] Preferably, the redundant acquisition circuit includes a first acquisition circuit and a second acquisition circuit;
[0017] The first acquisition circuit is connected to the current I / O interface;
[0018] The second acquisition circuit is connected to the analog acquisition port.
[0019] Preferably, the first acquisition circuit is connected to the current I / O interface based on safety level ASIL B(C);
[0020] The second acquisition circuit is connected to the analog acquisition port based on the security level ASIL A(C).
[0021] Preferably, the analog front-end chip is connected to the microcontroller unit in an end-to-end communication connection.
[0022] Preferably, the end-to-end communication connection conforms to security level ASIL C.
[0023] Preferably, both the first acquisition circuit and the second acquisition circuit are provided with an acquisition terminal, an amplification circuit, and a filtering circuit;
[0024] The acquisition terminal is connected to the splitter;
[0025] The amplifier circuit is connected to the acquisition terminal;
[0026] The filter circuit is connected to the amplifier circuit.
[0027] Preferably, there is one splitter.
[0028] A battery management system integrating the aforementioned shunt current acquisition structure.
[0029] The beneficial effects of this utility model are:
[0030] 1. This utility model adopts a redundant current acquisition circuit, which can redundantly acquire the signal of the shunt and transmit it based on different safety levels. While covering the open circuit fault caused by the shunt itself, it also makes the overall calculation index better.
[0031] 2. The allocation function safety level of the first acquisition circuit of this utility model is ASIL B(C), and the allocation function safety level of the second acquisition circuit is ASIL A(C). Based on the purpose of the acquisition circuit, the acquisition circuit is reasonably optimized while meeting the safety level, which helps to reduce costs.
[0032] 3. This utility model achieves current acquisition function with a single shunt. Through the optimized design of the overall circuit structure, the number of parts is reduced, and through quantitative calculation, it meets the requirements of high functional safety level.
[0033] 4. This utility model reduces space occupation and achieves cost optimization by simplifying hardware circuit components, thus realizing the circuit acquisition function.
[0034] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures pointed out in the description and the accompanying drawings. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 A schematic diagram of a shunt current acquisition structure according to this utility model is shown. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0038] like Figure 1The diagram illustrates a shunt current acquisition structure, comprising a single shunt, redundant acquisition circuitry, an analog front-end chip (AFE), and a microcontroller unit (MCU). The shunt is connected to the redundant acquisition circuitry, which converts the flowing current into a voltage signal. The redundant acquisition circuitry, based on different safety levels, is connected to the analog front-end chip, amplifying and filtering the voltage signal before transmitting the processed signal to the analog front-end chip. The analog front-end chip converts the received signal into a digital signal and transmits it to the connected microcontroller unit.
[0039] It should be noted that since the SN29500 does not contain structural components such as shunts, and there are no models or parameters for calculating shunt failure rates, the standard ISO 26262-11 provides two methods for calculating failure rates: one based on field data statistics and the other on accelerated life testing. Field statistics provided by a shunt manufacturer show that at a 99% confidence level, λ (failure rate) is 0.0149 FIT; at a 70% confidence level, λ (failure rate) is 0.0039 FIT. Accelerated life testing results for the shunt show that at a test temperature of 50°C and a confidence level of 90%, λ (failure rate) is 0.0046 FIT. Based on standard ISO 26262, a single-point failure rate of less than 0.1 FIT for ASIL C hardware components is acceptable; a rate less than 1 FIT requires specific measures, including sample testing and thermal aging tests on incoming materials. Based on the above calculation results of the failure rate, it can be seen that, whether based on field data statistics or accelerated life test calculations, the failure rate of the shunt is much less than 0.1 FIT, which belongs to the failure rate category 1. Therefore, the shunt itself does not need to be redundant and only a single shunt is required.
[0040] Furthermore, according to the ISO 26262 standard, shunt failure modes include open circuit, short circuit, and resistance drift. By analyzing the parameter information provided by a shunt manufacturer, the open circuit failure mode can be fully diagnosed, the drift tolerance is less than 3%, and it will not lead to a Function Under Stress Accident (FUSA) accident. Moreover, the Failure Modes, Effects, and Diagnostic Analysis (FMEDA) calculation can reach ASIL C. Therefore, a single shunt can meet the ASIL C functional safety level requirements.
[0041] Furthermore, Figure 1In order to address the high failure rate of the current acquisition after the shunt in the structure, and in the scenario where external communication is required, a redundant acquisition circuit needs to be designed. This redundant acquisition circuit consists of a first acquisition circuit and a second acquisition circuit, forming a dual redundant channel.
[0042] It should be noted that, in order to decompose the ASIL C functional safety level of the redundant acquisition circuit, an auxiliary current acquisition channel was designed in addition to the main current acquisition channel, which is used only for current acquisition. Specifically, the first acquisition circuit is assigned an ASIL B(C) functional safety level, and the second acquisition circuit is assigned an ASIL A(C) functional safety level.
[0043] Optionally, both the first and second acquisition circuits include an acquisition terminal, an amplifier circuit, and a filter circuit. The acquisition terminal is connected to a shunt to acquire the current signal; the amplifier circuit is connected to the acquisition terminal and amplifies the weak raw current signal using operational amplifiers and other devices to increase the signal strength for subsequent processing; the filter circuit is connected to the amplifier circuit and uses principles such as RC filtering to filter out noise and spurious signals, ensuring a stable and clean output signal, thereby achieving accurate data acquisition.
[0044] Furthermore, the analog front-end chip conforms to safety level ASIL C. This circuit includes a current I / O interface (Analog I / O), an analog acquisition port (Shunt I / O), a first analog-to-digital converter (ADC), and a second ADC. The current I / O interface and the analog acquisition port are connected based on different safety levels and redundant circuits. Specifically, the first acquisition circuit is connected to the current I / O interface based on safety level ASIL B(C), and the second acquisition circuit is connected to the analog acquisition port based on safety level ASIL A(C). Additionally, the first ADC is connected to the current I / O interface, and the second ADC is connected to the analog acquisition port.
[0045] It should be noted that in the circuit design, the analog front-end chip is designed with two independent analog-to-digital converters, which convert the analog signals from the analog acquisition port and the dedicated current I / O interface into digital signals for processing by the microcontroller unit (MCU), thus realizing the redundancy design of the entire current acquisition circuit.
[0046] Furthermore, the analog front-end chip and the microcontroller unit are connected in an end-to-end communication (E2E communication) connection with an ASIL C security level. End-to-end communication allows data to be transmitted directly from the source to the destination. The network nodes in between are only responsible for forwarding the data without processing or modifying it, ensuring the integrity, security and reliability of the data during transmission.
[0047] The following is about Figure 1 The working process of the structure is explained in detail below:
[0048] The shunt first converts the flowing current into a voltage signal. The acquisition channel amplifies and filters the voltage signal, and the current output is input to the analog front-end chip (AFE) through both the current I / O interface and the analog acquisition port. The first acquisition circuit is the main channel, assigned a functional safety level of ASIL B(C); the second acquisition circuit is the auxiliary channel, assigned a functional safety level of ASIL A(C), and is used only for current acquisition. Next, the analog front-end chip internally has two independent analog-to-digital converters (ADCs). The first ADC processes the analog signal from the current I / O interface, and the second ADC processes the analog signal from the analog acquisition port. The two acquisition circuits are connected to their respective ADCs to perform digitization on the two analog signals, achieving redundant acquisition. Finally, the analog front-end chip sends the digital signal to the MCU via end-to-end communication. The MCU performs final processing and decision-making on the acquired data. Finally, quantitative analysis of the current acquisition using a single shunt dual-channel current acquisition system shows that the overall functional safety index of the current acquisition structure meets the requirements of a high functional safety level. Therefore, the single shunt dual-current acquisition channel scheme can achieve significant cost optimization while ensuring ASIL C high functional safety level.
[0049] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A shunt current collection structure, characterized by, Includes a shunt, redundant acquisition circuitry, analog front-end chip, and microcontroller unit; The splitter is connected to the redundant acquisition circuit; The redundant acquisition circuits are connected to the analog front-end chip based on different security levels; The analog front-end chip is connected to the microcontroller unit.
2. The shunt current collection structure of claim 1, wherein, The analog front-end chip includes a current I / O interface, an analog acquisition port, a first analog-to-digital converter, and a second analog-to-digital converter. The current I / O interface and the analog acquisition port are connected based on different safety levels and redundant circuits; The first analog-to-digital converter is connected to the current I / O interface, and the second analog-to-digital converter is connected to the analog acquisition port.
3. The shunt current collection structure of claim 2, wherein, The analog front-end chip conforms to safety level ASIL C.
4. The shunt current collection structure of claim 2, wherein, The redundant acquisition circuit includes a first acquisition circuit and a second acquisition circuit; The first acquisition circuit is connected to the current I / O interface; The second acquisition circuit is connected to the analog acquisition port.
5. The shunt current collection structure of claim 4, wherein, The first acquisition circuit is connected to the current I / O interface based on safety level ASIL B(C); The second acquisition circuit is connected to the analog acquisition port based on the security level ASIL A(C).
6. The shunt current collection structure of claim 1, wherein, The analog front-end chip is connected to the microcontroller unit in an end-to-end communication connection.
7. The shunt current collection structure of claim 6, wherein, The end-to-end communication connection conforms to security level ASIL C.
8. The shunt current collection structure of claim 4, wherein, Both the first and second acquisition circuits are equipped with an acquisition terminal, an amplifier circuit, and a filter circuit. The acquisition terminal is connected to the splitter; The amplifier circuit is connected to the acquisition terminal; The filter circuit is connected to the amplifier circuit.
9. The shunt current collection structure of any of claims 1-8, wherein, There is one splitter.
10. A battery management system, characterized by, The device integrates a shunt current acquisition structure as described in any one of claims 1-9.