Current sensor and current sensor measurement system

Abstract

The present invention discloses a current sensor and a current sensor measurement system, which are suitable for vehicle batteries with a vehicle safety level, and include: a shunt, the shunt has a shunt resistor, and is used to divide the circuit passing through the shunt conductive area into two branch currents when measuring the current; a first current measurement unit and a second current measurement unit, which are used to respectively obtain the first branch measurement value flowing through the Hall sensor and the second branch measurement value flowing through the shunt resistor; a data processing unit, which is respectively connected to the first current measurement unit and the second current measurement unit in communication, and is used to respectively receive the first branch measurement value and the second branch measurement value obtained by the first current measurement unit and the second current measurement unit and output the measured current value. The current sensor with structural and electrical optimization design inside the current sensor realizes heterogeneous current measurement in the original installation space, and solves the problem of large volume and common cause failure of the redundant current measurement system.

Description

Technical Field

[0001] The present invention relates to the technical field of current sensors, and in particular to a current sensor used in a passenger car and a current sensor measurement system. Background Art

[0002] The current sensor is a device that measures the magnitude of current. The mainstream current sensors currently used in passenger vehicle battery packs can be classified into shunts, fluxgates, Hall, and other types according to the working principles of the core components used. Shunt sensors have been widely used in battery systems in recent years due to their low cost, high accuracy, and linearity. Since automotive high-voltage batteries are system components with high functional safety requirements, their multiple high functional safety level requirements are related to current measurement, such as thermal runaway, etc. As a result, the current battery system now has higher requirements for the accuracy of current measurement and the functional reliability of current measurement. Generally, mainstream manufacturers have requirements for current measurement devices that are no less than ASILC. Since current sensors that meet the ASILC level generally require redundant design from a hardware design perspective, the result is that the current measurement device is too large, resulting in serious waste of space.

[0003] The patent application with publication number CN117471159A and titled Current Sensor mentions a redundancy method. Although this method can achieve relatively good redundancy capability, this solution has certain implementation difficulties during processing and manufacturing. When designing current acquisition devices for current mainstream battery systems, because the system design requires high functional safety requirements, it is rare to have heterogeneous sensors in the same sensor; therefore, the mainstream design method is to connect sensors of the same principle in series, see Figure 1 As shown or the heterogeneous tandem method, see Figure 2 As shown, the reliability of current measurement is improved, and the diagnostic coverage of current measurement is improved. The disadvantages of these two solutions are: the dual fluxgate architecture is too expensive and has very few usage scenarios; the dual Hall is generally not used because of the poor linearity of Hall current measurement. The redundant current measurement system has problems such as large size, common cause failure, high processing difficulty, and high manufacturing cost. Summary of the invention

[0004] The purpose of the present invention is to provide a current sensor combining Hall and shunt, so as to solve the problems of large volume and common cause failure of the above-mentioned redundant current measurement system, combine the technical solution of the fusion of Hall and shunt, add Hall element to the original current measurement system based on shunt, and make the current sensor have a heterogeneous current measurement method without increasing the volume of the current measurement device. This method can make the current sensor have a higher functional safety level than a single Hall or single shunt sensor; avoid the common cause failure problem of sensors with the same principle, so that hardware failure has a higher detection and diagnosis coverage.

[0005] The present invention provides a current sensor, which is suitable for a vehicle battery with a vehicle safety level, comprising: A shunt, the shunt having a shunt resistor, used for dividing a circuit passing through a conductive area of ​​the shunt into two branches of current when measuring current; A first current measuring unit and a second current measuring unit, used to respectively obtain a first branch measurement value flowing through the Hall sensor and a second branch measurement value flowing through the shunt resistor; The data processing unit is respectively connected to the first current measuring unit and the second current measuring unit for receiving the first branch measurement value and the second branch measurement value obtained by the first current measuring unit and the second current measuring unit and outputting the measured current value.

[0006] Preferably, the first current measuring unit comprises a Hall sensor and a precision resistor, wherein the Hall sensor and the precision resistor are connected in series to form an equivalent resistor for directly obtaining a first branch measurement value flowing through the shunt resistor; The second current measurement unit includes a high-precision analog front-end unit for obtaining a second branch measurement value flowing through the shunt resistor; The data processing unit is further used to obtain a first total current value by filtering and adding the first branch measurement value and the second branch measurement value, and compare the first total current value with the total current value to obtain a ratio that does not exceed a preset ratio threshold, thereby diagnosing whether a current measurement fault occurs; Among them, the first branch measurement value measures the current value flowing through the Hall sensor, and the second branch measurement value is the current value calculated by the ratio of the voltage drop dU on both sides of the shunt resistor under the branch to the resistance value of the shunt resistor under the branch.

[0007] Preferably, the Hall sensor and the precision resistor are connected in series to form a first branch, and the conductive area where the shunt is located is a second branch. The two branches are connected in parallel to form a current measurement unit of the sensor; and the Hall sensor of the first branch is directly connected to the data processing unit for communication; the shunt of the second branch is connected to the input end of the high-precision analog front-end unit; and the output end of the high-precision analog front-end unit is connected to the data processing unit after isolation. Preferably, it also includes: The high-low voltage isolation unit includes a Hall sensor and an isolation communication unit. The Hall sensor is directly connected to the data processing unit, and the high-precision analog front-end unit is connected to the data processing unit through the isolation communication unit. It is used to achieve isolation of the high-voltage area and the low-voltage area corresponding to the two sides of the high-low voltage isolation unit according to the isolation capability of the Hall sensor itself and the isolation communication unit, so as to avoid common cause failure when using the same type of data isolation units.

[0008] Preferably, the shunt resistor and the precision resistor are configured according to a preset ratio.

[0009] Preferably, the data processing unit is also used to calculate the second total current value and the third total current value according to the ratio between the shunt resistor and the precision resistor, respectively; and to identify the difference between the total currents according to the sizes of the first total current value, the second total current value and the third total current value, and to diagnose a current measurement failure when the difference exceeds a preset threshold.

[0010] Preferably, the first branch current and the second branch current are selected according to a measuring range of the measured current and distributed according to the selected ratio, thereby ensuring that the current does not exceed the rated capacity of each measuring element.

[0011] Preferably, the first current measuring unit and the second current measuring unit are respectively arranged close to the shunt resistor, and both ends of the shunt resistor are connected to a peripheral load and a power supply.

[0012] Preferably, the data processing unit obtains current data in the Hall sensor through SPI or IIC, and / or obtains voltage data of the high-precision analog front-end unit through SPI or IIC of the high-low voltage isolation unit.

[0013] The present invention also provides a current sensor measurement system, comprising the current sensor as described above.

[0014] With respect to the prior art, the present invention has the following beneficial effects: The current sensor provided by the present invention proposes a current sensor combining Hall and shunt, which is a technical solution that combines the fusion of Hall and shunt. The solution adds a Hall element to the original shunt-based current measurement system, so that the current sensor has a heterogeneous current measurement method without increasing the volume of the current measurement device. This method can make the current sensor have a higher functional safety level than a single Hall or single shunt form sensor; because the hardware architecture of the solution avoids the common cause failure problem of sensors with the same principle by using different measurement principles and data transmission paths, the hardware failure has a higher detection and diagnosis coverage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the architecture of a homogeneous (dual shunt) current measurement system in the background technology of an embodiment of the present invention; Figure 2 The heterogeneous current measurement system architecture in the background technology of the embodiment of the present invention; Figure 3 1 is a principle block diagram of a current sensor in an embodiment of the present invention.

[0016] Among them, shunt resistor-23, first current measurement unit-1, second current measurement unit-2, high and low voltage isolation unit-3, Hall sensor-24, precision resistor-25, digital and power isolation unit-26, isolated communication unit-27, high-precision analog front-end unit 28, high and low voltage isolation unit-33, data processing unit-32, first branch current-29, second branch current-35. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1 The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0019] It should be noted that the concepts such as "once" and "second" mentioned in the present application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0020] It should be noted that the modifications of "one" and "plurality" mentioned in the disclosure of this application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0021] like Figure 1 As shown, an embodiment of the present invention provides a current sensor suitable for a vehicle battery with a high functional safety level used in a vehicle, comprising: A shunt having a shunt resistor 23, used for dividing a circuit passing through a conductive area of ​​the shunt into two branch currents when measuring current; The first current measuring unit 1 and the second current measuring unit 2 are used to respectively obtain a first branch measurement value flowing through the Hall sensor 24, namely a first branch current 29, and a second branch measurement value flowing through the shunt resistor 23, namely a second branch current 35; The data processing unit 32 is respectively connected to the first current measuring unit 1 and the second current measuring unit 2 for respectively receiving the first branch measurement value and the second branch measurement value obtained by the first current measuring unit 1 and the second current measuring unit 2 and outputting the measured current value.

[0022] Specifically, the first current measuring unit 1 includes a Hall sensor 24 and a precision resistor 25, wherein the Hall sensor 24 and the precision resistor 25 are connected in series to form an equivalent resistor, and is used to directly obtain a measurement value of a first branch flowing through the Hall sensor 24; The second current measurement unit 2 comprises a high-precision analog front-end unit 28 for obtaining a second branch measurement value flowing through the shunt resistor 23; The data processing unit 32 is further used to obtain a first total current value by filtering and adding the first branch measurement value and the second branch measurement value, and compare the first total current value with the total current value to obtain a ratio that does not exceed a preset ratio threshold, thereby diagnosing whether a current measurement fault occurs; Among them, the first branch measurement value measures the current value flowing through the Hall sensor 24, and the second branch measurement value is the current value calculated by the ratio of the voltage drop dU on both sides of the shunt resistor 23 under the branch to the resistance value of the shunt resistor 23 under the branch. The Hall sensor 24 directly collects the magnitude of the first branch current 29.

[0023] The main contents of the present invention are as follows Figure 3As shown in the dotted box, the focus is on the data interaction and principle design according to the above structure with Hall sensor / Hall sensor 24, shunt resistor 23, high-precision analog front-end unit 28, precision resistor 25, high-low voltage isolation unit 3, and data processing unit 32. When measuring the current, the branch current is divided into two parts: the first branch current 29 and the second branch current 35. This embodiment meets the needs of heterogeneous redundant measurement. Through this solution, only two components, Hall sensor 24 and precision resistor 25, can be added to the original shunt sensor to realize heterogeneous redundant measurement of current, thereby ensuring high reliability of current measurement data. In terms of cost, the cost of the two components, Hall sensor 24 and precision resistor 25, is equivalent to that of a single analog sensor. The analog sensor requires secondary processing of post-stage AFE and interface isolation, which is about 25% of the cost of the fluxgate, and the cost saving effect is significant. The Hall sensor 24 used in this embodiment is a Hall sensor, which is small in size, and because the outer shell can pull the distance between the Hall and other components, the interference of stray magnetic fields is significantly reduced. The current flowing through the Hall sensor 24 and the shunt resistor 23 is only a part, and even if the communication of one of the links fails, the basic current measurement function can be met without causing overall failure. The common cause failure rate is effectively reduced. Through the above scheme, the current sensor with structural and electrical optimization design inside the current sensor is realized, and a heterogeneous current measurement device is realized in the original installation space, so as to solve the problem of large volume and common cause failure of the above redundant current measurement system. This scheme uses CAN communication as a carrier in signal interaction. In hardware design, the low-voltage part function is isolated from the high-voltage part, and CAN is on the low-voltage side, so that the whole system has good insulation. Since the Hall of this scheme is small in size, it is less sensitive to stray magnetic fields. At the same time, in order to overcome the problem of high processing difficulty, the main detection parts of this scheme are all realized on PCB, which can ensure good manufacturing accuracy and reduce manufacturing costs.

[0024] In the process of detecting the current, the shunt resistor 23 and the precision resistor 25 are configured according to a preset ratio, and thus according to Kirchhoff's law, the ratio of the first branch current 29 to the second branch current 35 is also known.

[0025] In this embodiment, the current sensor also includes: a high and low voltage isolation unit 3, including a Hall sensor 24 and an isolation communication unit 27, the Hall sensor 24 is directly connected to the data processing unit 32, and the AFE high-precision analog front-end unit 3 is connected to the data processing unit 32 through the isolation communication unit 27, and is used to isolate the high-voltage area and the low-voltage area corresponding to both sides of the high and low voltage isolation unit 3 according to the isolation capability of the Hall sensor 24 itself and the isolation communication unit 27, so as to avoid common cause failure when using the same / same type of data isolation units, and prevent electric shock injuries. The high-precision analog front-end unit 28 can be a high-precision ADC or an AFE high-precision analog front-end, and the Hall sensor 24 here is a Hall sensor with power supply isolation, that is, it includes a digital and power supply isolation unit 26.

[0026] Specifically, the first branch current 29 and the second branch current 35 are selected according to the measurement range of the measured current and distributed according to the selected ratio, thereby ensuring that the current does not exceed the rated capacity of each measuring element.

[0027] Specifically, the Hall sensor 24 and the precision resistor 25 are connected in series to form a first branch, and the conductive area where the shunt is located is a second branch. The two branches are connected in parallel to form a current measurement unit of the sensor; and the Hall sensor 24 of the first branch is directly connected to the data processing unit for communication; the shunt of the second branch is connected to the input end of the high-precision analog front-end unit 28; and the output end of the high-precision analog front-end unit 28 is connected to the data processing unit after isolation. Among them, one end of the shunt resistor 23 is electrically connected to one end of the precision resistor 25, the other end of the precision resistor 25 is electrically connected to one end of the Hall sensor 24, and the other end of the Hall sensor 25 is electrically connected to the other end of the shunt resistor 23.

[0028] Specifically, the data processing unit 32 is also used to calculate the second total current value and the third total current value according to the ratio between the shunt resistor 23 and the precision resistor 25; according to the magnitude of the first total current value, the second total current value and the third total current value and identify the difference between the total currents, and diagnose that the current measurement is faulty when the difference exceeds a preset threshold. The two currents obtained by the two current measurement units are expanded into three current data, and the reliability of the current measurement is calculated, which cannot exceed half of the measurement accuracy. The difference is judged differently according to different ranges. The simplest one is that the ratio exceeds a certain range, which is abnormal.

[0029] Specifically, the first current measurement unit 1 and the second current measurement unit 2 are respectively arranged near the shunt resistor 23, and are both arranged on the PCB board. The two ends of the shunt resistor 23 are connected to the peripheral load and the power supply. The compact sensor layout achieves a higher ASIL level without increasing the volume of the original shunt sensor, reduces the hardware isolation cost of the main control, does not need to use a longer high-voltage cable, and reduces the difficulty of wiring harness layout. The current sensor hardware design structure provided in this embodiment increases the cost by about 15% based on the original sensor, but reduces the horizontal space use of the copper bar of 84mm, which is the size of the general shunt sensor, and the vertical dimension of the copper bar calculated by about 40mm, which is the installation radius of the 500A fluxgate current sensor, when the measurement system is designed. During the test, the single point failure mode of the sensor was tested by deliberately cutting off the Hall sensor 24 and the isolation communication unit 27. It was found that even if one sensor cannot work, the current test accuracy can still be guaranteed to be better than 2% through a good redundancy mechanism. When the shunt fails, the correction accuracy of the Hall in the high temperature range; the actual single shunt measurement result accuracy can be within 0.5%.

[0030] Specifically, the data processing unit 32 obtains the current data in the Hall sensor 24 through SPI or IIC, and obtains the voltage data of the high-precision analog front-end unit 28 through SPI or IIC of the high-low voltage isolation unit 3 .

[0031] Implementation The detailed implementation steps are as follows: Step 1: Select the distribution ratio of the first branch current 29 and the second branch current 35 according to the measuring range of the measured current to ensure that the current does not exceed the rated capacity of each measuring element; Step 2: Lay out the relative positions of the Hall sensor 24, the shunt resistor 23, the high-precision analog front-end unit 28, the precision resistor 25, the high-low voltage isolation unit 3, and the data processing unit 32 on the PCB board according to the measurement; Step 3: Implementing the current measurement function of the Hall sensor 24 and the current detection function of the precision resistor 25 in the data processing unit 32; Step 4: The data processing unit 32 periodically calculates the first branch current 29 and the second branch current 35 respectively, and adds them after filtering to obtain a first total current; Step 5: Then, according to the ratio between the shunt resistor 23 and the precision resistor 25, the second total current, i.e., the Hall proportional total current, and the third total current, i.e., the total current of the precision resistor 25, are calculated respectively; Step 6: Determine the magnitude of the three total currents and their differences to determine the credibility of the current data and diagnose whether the current measurement hardware is faulty; and output the most credible measured current value at the same time.

[0032] The present invention also provides a current sensor measurement system, comprising the current sensor provided by the above embodiment.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A current sensor, characterized in that: Vehicle batteries with safety levels suitable for vehicle use, including: A shunt, the shunt having a shunt resistor, used for dividing a circuit passing through a conductive area of ​​the shunt into two branches of current when measuring current; A first current measuring unit and a second current measuring unit, at least one of the current measuring units includes a Hall sensor, for respectively obtaining a first branch measurement value of the current flowing through the Hall sensor and a second branch measurement value of the current flowing through the shunt resistor; The data processing unit is respectively connected to the first current measuring unit and the second current measuring unit for receiving the first branch measurement value and the second branch measurement value obtained by the first current measuring unit and the second current measuring unit and outputting the measured current value.

2. The current sensor according to claim 1, characterized in that The first current measuring unit comprises a Hall sensor and a precision resistor, wherein the Hall sensor and the precision resistor are connected in series to form an equivalent resistor for directly obtaining a measurement value of a first branch current flowing through the Hall sensor; The second current measurement unit includes a high-precision analog front-end unit for obtaining a second branch measurement value flowing through the shunt resistor; The data processing unit is further used to obtain a first total current value by filtering and adding the first branch measurement value and the second branch measurement value, and compare the first total current value with the total current value to obtain a ratio that does not exceed a preset ratio threshold, thereby diagnosing whether a current measurement fault occurs; Among them, the first branch measurement value measures the current value flowing through the Hall sensor, and the second branch measurement value is the current value calculated by the ratio of the voltage drop dU on both sides of the shunt resistor under the branch to the resistance value of the shunt resistor under the branch.

3. The current sensor according to claim 2, characterized in that: The Hall sensor and the precision resistor are connected in series to form a first branch, and the conductive area where the shunt is located is a second branch. The two branches are connected in parallel to form a current measurement unit of the sensor; and the Hall sensor of the first branch is directly connected to the data processing unit for communication; the shunt of the second branch is connected to the input end of the high-precision analog front-end unit; and the output end of the high-precision analog front-end unit is connected to the data processing unit after isolation.

4. The current sensor according to claim 2, characterized in that: Also includes: The high-low voltage isolation unit includes a Hall sensor and an isolation communication unit. The Hall sensor is directly connected to the data processing unit, and the high-precision analog front-end unit is connected to the data processing unit through the isolation communication unit. It is used to achieve isolation of the high-voltage area and the low-voltage area corresponding to the two sides of the high-low voltage isolation unit according to the isolation capability of the Hall sensor itself and the isolation communication unit, so as to avoid common cause failure when using the same type of data isolation units.

5. The current sensor according to claim 2, characterized in that: The shunt resistor and the precision resistor are configured according to a preset ratio.

6. The current sensor according to claim 5, characterized in that The data processing unit is further used to calculate the second total current value and the third total current value respectively according to the ratio between the shunt resistor and the precision resistor; and to identify the difference between the total currents according to the magnitudes of the first total current value, the second total current value and the third total current value, and to diagnose a current measurement failure when the difference exceeds a preset threshold.

7. The current sensor according to claim 1, characterized in that The first branch current and the second branch current are selected according to the measurement range of the measured current and distributed according to the selected ratio, thereby ensuring that the current does not exceed the rated capacity of each measuring element.

8. The current sensor according to claim 1, wherein: The first current measuring unit and the second current measuring unit are respectively arranged close to the shunt resistor, and two ends of the shunt resistor are connected to a peripheral load and a power supply.

9. The current sensor according to claim 1, characterized in that: The data processing unit obtains the current data in the Hall sensor through SPI or IIC, and / or obtains the voltage data of the high-precision analog front-end unit through SPI or IIC of the high-low voltage isolation unit.

10. A current sensor measurement system, characterized in that: Comprising a current sensor as claimed in any one of claims 1 to 9.

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