Calibration system and method for current sensor

Abstract

The present invention provides a calibration system and method for a current sensor. The system includes a control module, a constant current module, a sensing device, a first feedback module, and a second feedback module. The control module is connected to the constant current module and configured to output a constant current. The sensing device is connected in series to the output of the constant current module and is configured to divide the constant current and output a first voltage, as well as output a divided test current to the current sensor. The first feedback module is configured to receive a first voltage and send it to the control module. The second feedback module is configured to receive a second voltage from the current sensor and send it to the control module. The control module is further configured to receive the first and second voltages and calibrate the current sensor based on the constant current, the first voltage, and the second voltage. The present invention improves the accuracy of the current sensor and reduces the cost of the entire calibration system.

Description

Technical Field

[0001] The present invention generally relates to the field of battery management, and in particular to a calibration system and method for a current sensor. Background Art

[0002] Currently, power battery management systems primarily use the following two types of current sensors for current sampling. One type is the Hall-effect current sensor, which indirectly measures the current in a conductor by measuring the magnetic field strength near the current. Hall-effect current sensors are contactless and can measure large currents, but they suffer from low accuracy and large temperature drift. The other type is the shunt resistor current sensor, connected in series in a circuit. It indirectly measures the current in a conductor by measuring the voltage across the shunt resistor.

[0003] Due to the generally high cost of large-current shunt resistor current sensors and large-current Hall-effect current sensors, many manufacturers only use a single large-current shunt resistor current sensor or a single large-current Hall-effect current sensor for current sampling, which cannot meet the national standard GBT 34131-2017, which requires the single-cluster current sampling error in the battery management system to be no more than 0.2% accuracy.

[0004] Therefore, there is an urgent need for a low-cost, high-precision calibration system to calibrate the current sensor in the battery management system. Summary of the Invention

[0005] The present invention aims to solve the above problems and provides a calibration system and method for a current sensor.

[0006] In order to solve the above technical problems, the present invention provides a calibration system for a current sensor, comprising a control module, a constant current module, a sensing device, a first feedback module and a second feedback module; the control module is connected to the constant current module, and the control module is used to configure the constant current module to output a constant current; the sensing device is connected in series to the output end of the constant current module, and the sensing device is used to divide the constant current and output a first voltage, and to output the divided test current to the current sensor; the first feedback module

[0007] -1- is connected to the sensing device and the control module respectively, the first feedback module is used to receive the first voltage and send the first voltage to the control module; the second feedback module is connected to the current sensor and the control module respectively, the second feedback module is used to receive a second voltage from the current sensor and send the second voltage to the control module, wherein the second voltage reflects the test current flowing through the current sensor; the control module is also used to receive the first voltage and the second voltage, and calibrate the current sensor according to the constant current, the first voltage and the second voltage.

[0008] In one embodiment of the present invention, the sensing device has a first current range, the current sensor has a second current range, and the first current range is smaller than the second current range.

[0009] In one embodiment of the present invention, the sensing device is a shunt resistor, and the current sensor is a Hall sensor or a shunt resistor.

[0010] In one embodiment of the present invention, the constant current module includes: a transistor; a sampling resistor, the sampling resistor being connected to the collector of the transistor; a voltage regulator, connected to the sampling resistor and configured to provide a voltage to the sampling resistor; an operational amplifier circuit, connected in parallel with the sampling resistor and configured to amplify the voltage across the sampling resistor to obtain an amplified voltage and transmit the amplified voltage; and a linear constant voltage and constant current driver chip, connected to the base of the transistor and configured to receive the amplified voltage and control the emitter of the transistor to output the constant current according to the amplified voltage.

[0011] In one embodiment of the present invention, the first feedback module includes a first AD sampling circuit and a first isolation circuit, the first AD sampling circuit is connected to the sensing device, and the first isolation circuit is connected to the control module; the second feedback module includes a second AD sampling circuit and a second isolation circuit, the second AD sampling circuit is connected to the current sensor, and the second isolation circuit is connected to the control module.

[0012] In one embodiment of the present invention, the control module calibrates the current sensor according to the constant current, the first voltage and the second voltage, including: the control module is configured to calculate a test current value of the test current according to the first voltage, calculate a detection current value of the test current flowing through the current sensor according to the second voltage, calculate the ratio between the test current value, the detection current value and the constant current value of the constant current, and if the ratio of the test current value to the constant current value and the ratio of the test current value to the detection current value are both within a first interval, then the ratio of the test current value to the detection current value is used as the calibration coefficient of the current sensor.

[0013] In one embodiment of the present invention, the control module is further configured to determine whether the current sensor and the second feedback module are faulty based on the test current value and the detection current value; if the detection current value is zero or the ratio of the test current value to the detection current value exceeds the first interval, the current sensor and the second feedback module are faulty.

[0014] In one embodiment of the present invention, the control module is further configured to diagnose the fault of the sensing device based on the constant current value and the test current value. If the ratio of the test current value to the constant current value is less than a first threshold value, the fault of the sensing device is diagnosed as a short circuit; if the test current value is fully deviated, the fault of the sensing device is diagnosed as an open circuit.

[0015] In one embodiment of the present invention, a current lead-out line is further included, for leading the test current to the current sensor.

[0016] In one embodiment of the present invention, a digital isolator is further included, located between the control module and the constant current module, and is used to isolate the current between the control module and the constant current module.

[0017] Another aspect of the present invention also provides a calibration method for a current sensor, comprising: outputting a constant current; dividing the constant current and outputting a first voltage, and outputting a divided test current to the current sensor; receiving the first voltage and a second voltage from the current sensor, wherein the second voltage reflects the test current flowing through the current sensor; and calibrating the current sensor based on the constant current, the first voltage, and the second voltage.

[0018] In one embodiment of the present invention, calibrating the current sensor according to the constant current, the first voltage and the second voltage includes: calculating a test current value according to the first voltage; calculating a detection current value according to the second voltage; calculating the ratio between the test current value, the detection current value and the constant current value of the constant current, and if the ratio of the test current value to the constant current value and the ratio of the test current value to the detection current value are both within a first interval, then using the ratio of the test current value to the detection current value as the calibration coefficient of the current sensor.

[0019] In one embodiment of the present invention, the constant current is divided by a sensing device to output a first voltage, the sensing device has a first current range, the current sensor has a second current range, and the first current range is smaller than the second current range.

[0020] In one embodiment of the present invention, the sensing device is a shunt resistor, and the current sensor is a Hall sensor or a shunt resistor.

[0021] In one embodiment of the present invention, the present invention further includes diagnosing a fault of the sensor device according to the constant current value and the test current value. If the ratio of the test current value to the constant current value is less than a first threshold value, the fault of the sensor device is diagnosed as a short circuit. If the test current value is fully deviated, the fault of the sensor device is diagnosed as a short circuit.

[0022] -3- The fault of the sensor device is a short circuit.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The calibration system for a current sensor of the present invention calibrates the current sensor by adding a constant current module and a small-range high-precision sensing device, thereby improving the accuracy of the current sensor and reducing the cost of the entire calibration system; the independent first feedback module and the second feedback module respectively feed back signals, thereby avoiding the simultaneous failure of two or more modules in the system due to a common cause; and by configuring the control module to determine whether a module in the calibration system has failed based on a constant current value, a test current value, and a detection current value, the faulty module in the calibration system can be quickly located, facilitating maintenance by maintenance personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, in which:

[0026] Figure 1 is a system block diagram of a calibration system for a current sensor according to an embodiment of the present invention;

[0027] Figure 2 is a circuit diagram of a constant current module according to an embodiment of the present invention;

[0028] Figure 3 is a schematic structural diagram of a first feedback module according to an embodiment of the present invention;

[0029] Figure 4 is a circuit diagram of an AD sampling circuit according to an embodiment of the present invention;

[0030] Figure 5 is a schematic structural diagram of a second feedback module according to an embodiment of the present invention;

[0031] Figure 6 is a circuit diagram of an AD sampling circuit according to an embodiment of the present invention;

[0032] Figure 7 is a system block diagram of a calibration system for a current sensor according to another embodiment of the present invention;

[0033] Figure 8 FIG. 4 is a flow chart of a method for calibrating a current sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0035] As used in this application and claims, unless the context clearly indicates an exception, "a", "an", "an", "an" or "an" shall be construed as follows:

[0036] -4- The words "a," "an," and / or "the" do not refer to the singular but may include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0037] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0038] In the description of this application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0039] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0040] In addition, it should be noted that the use of terms such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning.

[0041] -5- meaning, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terminology used in this application is selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application must be understood not only by the actual terms used, but also by the meaning implied by each term.

[0042] It should be understood that when a component is referred to as being “on another component,” “connected to another component,” “coupled to another component,” or “contacting another component,” it can be directly on, connected to, coupled to, or contacting the other component, or intervening components may be present. In contrast, when a component is referred to as being “directly on another component,” “directly connected to,” “directly coupled to,” or “directly contacting” another component, there are no intervening components. Similarly, when a first component is referred to as being “electrically in contact with” or “electrically coupled to” a second component, an electrical path exists between the first and second components that allows current to flow. This electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between the conductive components.

[0043] Flowcharts are used in this application to illustrate the operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0044] Figure 1 FIG. 1 is a system block diagram of a calibration system 100 for a current sensor according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the current sensor to be calibrated is a shunt resistor current sensor 1. Figure 1Marked as SHUNT. When the shunt resistor current sensor 1 leaves the factory or needs to be calibrated, the switch S is disconnected and calibrated by the calibration system 100 for the current sensor of this embodiment (hereinafter referred to as the calibration system 100). The calibration system 100 includes a control module 11, a constant current module 12, a sensing device 13, a first feedback module 14 and a second feedback module 15. The control module 11 is connected to the constant current module 12 via an I2C bus 110. The control module 11 is used to configure the constant current module 12 to output a constant current I1. The sensing device 13 is connected in series to the output end of the constant current module 12, and the sensing device 13 is used to divide the constant current I1 and output a first voltage V1, and to output the divided test current I2 to the shunt resistor current sensor 1. The first feedback module 14 is connected to the sensing device 13 and the control module 11 respectively, and the first feedback module 14 is used to receive the first voltage V1 and send the first voltage V1 to the control module 11. The second feedback module 15 is connected to the shunt resistor current sensor 1 and the control module 11 respectively. Second feedback module 15

[0045] -6- is used to receive a second voltage V2 from the shunt resistor current sensor 1 and send the second voltage V2 to the control module 11, wherein the second voltage V2 reflects the test current I2 flowing through the shunt resistor current sensor 1; the control module 11 is also used to receive the first voltage V1 and the second voltage V2, and calibrate the shunt resistor current sensor 1 according to the constant current I1, the first voltage V1 and the second voltage V2.

[0046] Continue to refer to Figure 1 In this embodiment, sensor device 13 is a shunt resistor current sensor. The difference between sensor device 13 and shunt resistor current sensor 1 is that sensor device 13 has a first current range, while shunt resistor current sensor 1 has a second current range, and the first current range is smaller than the second current range. In other words, shunt resistor current sensor 1 can measure larger current values, while sensor device 13 can only measure smaller current values. Because the current range of sensor device 13 is smaller than that of shunt resistor current sensor 1, the cost of sensor device 13 is lower than that of shunt resistor current sensor 1.

[0047] In some embodiments, the control module 11 calibrates the shunt resistor current sensor 1 according to the constant current I1, the first voltage V1, and the second voltage V2, including: the control module 11 is configured to calculate the test current value A2 of the test current I2 according to the first voltage V1 and the resistance of the sensor device 13. The detection current value A3 of the test current I2 flowing through the shunt resistor current sensor 1 is calculated according to the second voltage V2 and the resistance of the shunt resistor current sensor 1. The current value of the constant current I1 is recorded as the constant current value A1. The control module 11 is configured to calibrate the shunt resistor current sensor 1 according to the following rules. Determine whether the ratio of the test current value A2 to the constant current value A1 and the ratio of the test current value A2 to the detection current value A3 satisfy the following formula:

[0048] |A2 / A1-1|<T and |A2 / A3-1|<T

[0049] Where T is the current accuracy value, and the current accuracy value can be set as needed. Taking T as 0.1 as an example, |A2 / A1-1|<0.1 and |A2 / A3-1|<0.1, then the range of A2 / A1 is in the range of 0.9~1.1, and the range of A2 / A3 is also in the range of 0.9~1.1, and the above formula is valid. If the ratio of the test current value A2 to the constant current value A1 and the ratio of the test current value A2 to the detection current value A3 meet the above formula, then the ratio of the test current value A2 to the detection current value A3 is used as the calibration coefficient of the shunt resistor current sensor 1. The calibration formula of the shunt resistor current sensor 1 is as follows:

[0050] I0=(A2 / A3)*I3

[0051] Wherein, I3 is the current value measured by the shunt resistor type current sensor 1 when the switch S is closed, and I0 is the current value after calibration of the shunt resistor type current sensor 1.

[0052] Figure 2 FIG. 1 is a circuit diagram of a constant current module 12 according to an embodiment of the present invention. The constant current module 12 includes a linear constant current module 12.

[0053] -7- Linear constant voltage and current driver chip U2, transistor Q1, voltage regulator U11, sampling resistor R2, and op amp circuit U10. Sampling resistor R2 is connected to the collector of transistor Q1, and voltage regulator U11 is connected to sampling resistor R2. Voltage regulator U11 is used to provide voltage to sampling resistor R2. In this embodiment, voltage regulator U11 is a TLV752. Voltage regulator U11 is configured to step down the 5V isolated voltage provided by the power supply to 1.1V, and then provide this 1.1V voltage to sampling resistor R2. Op amp circuit U10 is connected in parallel with sampling resistor R2 and is used to amplify the voltage across sampling resistor R2 to obtain an amplified voltage FB, which is then sent to linear constant voltage and constant current driver chip U2. The voltage amplification factor of the voltage across sampling resistor R2 by op amp circuit U10 can be 50 times, or other multiples. This application does not impose any restrictions on the amplification factor. The connection between the linear constant voltage and constant current driver chip U2 and the base of the transistor Q1 is used to receive the amplified voltage FB and control the transistor Q1 to be in the linear working area according to the amplified voltage FB, so that the emitter of the transistor Q1 outputs a constant current I1. Figure 2 The middle sensing device is resistor R1. The constant current I1 passes through resistor R1 and the voltages at both ends are I2_OUT+ and I2_OUT. In this embodiment, the resistance of the sampling resistor R2 is 0.1 ohm. The constant current module 12 outputs the current according to the following formula:

[0054] I1=1A*DPWM

[0055] Wherein, DPWM is the duty cycle of a pulse width modulation (PWM) signal, that is, the constant current I1 can be realized in the range of 0-1A through PWM programming.

[0056] Figure 3 FIG. 1 is a schematic diagram of the structure of the first feedback module according to an embodiment of the present invention. Figure 3 As shown, the first feedback module 14 includes an AD sampling circuit 141 and an isolation circuit 142. The AD sampling circuit 141 is connected in parallel with the sensor device 13, and the isolation circuit 142 is connected to the control module 11. The AD sampling circuit 141 is configured to perform analog-to-digital conversion on a first voltage V1 across the sensor device 13 and transmit the converted first voltage to the isolation circuit 142. The isolation circuit 142 receives the converted first voltage V1 and transmits the converted first voltage V1 to the control module 11 via the I2C bus 110.

[0057] Figure 4 FIG. 1 is a circuit diagram of an AD sampling circuit 141 according to an embodiment of the present invention. Figure 4As shown, the AD sampling circuit 141 includes a current monitor U3 and supporting components that implement the functions of the current monitor U3. In this embodiment, the model of the current monitor U3 is INA226AIDGSR. The INA226AIDGSR is a current shunt and power monitor with a PC interface. The current monitor U3 receives the voltage drop between I2_OUT+ and I2_OUT, performs analog-to-digital conversion on the voltage drop between I2_OUT+ and I2_OUT, and then sends the converted value to the isolation circuit (not shown) via the SDA and SCKL terminals of the current monitor U3.

[0058] Figure 5 FIG. 1 is a schematic diagram of the structure of the second feedback module according to an embodiment of the present invention. Figure 5 As shown, in a

[0059] In some embodiments, the second feedback module 15 includes an analog-to-digital sampling circuit 151 and a digital isolator 152. The sampling circuit 151 is connected to the shunt resistor current sensor 1, and the isolation circuit 152 is connected to the control module 11. The analog-to-digital sampling circuit 151 is configured to perform analog-to-digital conversion on the second voltage V2 across the shunt resistor current sensor 1 and transmit the converted second voltage to the isolation circuit 152. The isolation circuit 152 receives the converted second voltage V2 and transmits it to the control module 11 via the I2C bus 110.

[0060] Figure 6 FIG. 1 is a circuit diagram of an AD sampling circuit 151 according to an embodiment of the present invention. Figure 6 As shown, the AD sampling circuit 151 includes a current monitor U5 and supporting components that implement the functions of the current monitor U5. In this embodiment, the model of the current monitor U5 is INA226AIDGSR. INA226AIDGSR is a current shunt and power monitor with a PC interface. The current monitor U5 is sensitive to the second voltage across the shunt resistor current sensor (i.e., SHUNT + and SHUNT - The voltage drop between the current monitor U5 and the current monitor U5 is then converted into analog-to-digital value, and the converted value is then sent to the isolation circuit (not shown) through the SDA and SCKL of the current monitor U5.

[0061] In some embodiments, as Figure 1 As shown, the calibration system 100 is arranged inside the battery management system BMS, and the calibration system 100 also includes a current lead 16. The current lead 16 is used to lead the test current I2 provided by the sensor device 13 to the shunt resistor current sensor 1 outside the battery management system BMS.

[0062] In some embodiments, as Figure 1As shown, the calibration system 100 further includes a digital isolator (not shown), which is located between the control module 11 and the constant current module 12 and is used to isolate the current between the control module 11 and the constant current module 12.

[0063] In some embodiments, the control module 11 is further configured to determine whether a module in the calibration system 100 has failed based on the constant current value A1, the test current value A2, and the detection current value A3. Taking a current accuracy value of 0.1 as an example, the following fault table (Table 1) is used to determine whether a module in the calibration system 100 has failed.

[0064] Table 1

[0065]

[0066]

[0067] According to Table 1, if the constant current value A1 is equal to zero, the constant current module 12 fails; if the ratio of the test current value A2 to the constant current value A1 is less than 0.9, the sensor device 13 fails and the fault type is short circuit; if the test current value A2 is fully deflected, the sensor device 13 fails and the fault type is open circuit; if the ratio of the test current value A2 to the constant current value A1 is not in the range of 0.9 to 1.1, the constant current module 12 or the first feedback module 14 fails; if the test current value A2 is equal to zero, the first feedback module 14 or the current lead 16 fails; if the detection current value A3 is equal to zero or the ratio of the test current value A2 to the detection current value A3 is not in the range of 0.9 to 1.1, the shunt resistor current sensor 1 or the second feedback module 15 fails.

[0068] Figure 7 FIG. 1 is a system block diagram of a calibration system for a current sensor according to another embodiment of the present invention. Figure 7As shown, in this embodiment, the current sensor to be calibrated is a Hall-type current sensor 2. When the Hall-type current sensor 2 leaves the factory or requires calibration, switch S is disconnected, and the current sensor calibration system 700 (hereinafter referred to as calibration system 700) of this embodiment is calibrated. Calibration system 700 includes a control module 71, a constant current module 72, a sensing device 73, a first feedback module 74, a second feedback module 77, and a current lead 76. The difference between calibration system 700 and calibration system 100 in the first embodiment is that current lead 76 is not directly connected to the Hall-type current sensor 2. The Hall-type current sensor 2 includes a magnetic ring and a Hall chip. Current lead 76 passes through the magnetic ring of the Hall-type current sensor 2. The magnetic ring senses a magnetic field strength due to the current flowing through current lead 76. The Hall chip of the Hall-type current sensor 2 detects the magnetic field strength within the magnetic ring and obtains a second voltage V2. The control module 71 is configured to search the voltage and current correspondence table of the Hall-type current sensor based on the converted second voltage signal to obtain a detected current value A3.

[0069] The calibration system for a current sensor of the present invention calibrates the current sensor by adding a constant current module and a small-range high-precision sensing device, thereby improving the accuracy of the current sensor and reducing the cost of the entire calibration system; the independent first feedback module and the second feedback module respectively feed back signals, thereby avoiding the simultaneous failure of two or more modules in the system due to a common cause; and by configuring the control module to determine whether a module in the calibration system has failed based on a constant current value, a test current value, and a detection current value, the faulty module in the calibration system can be quickly located, facilitating maintenance by maintenance personnel.

[0070] The present invention also provides a method for calibrating a current sensor. The method for calibrating a current sensor can be performed using any of the above-described embodiments of the calibration system for a current sensor. Therefore, for a detailed description of the method for calibrating a current sensor, reference can be made to the description of the above-described calibration system for a current sensor, and will not be repeated here.

[0071] Figure 8 FIG. 1 is a flow chart of a method for calibrating a current sensor according to an embodiment of the present invention. Figure 8 As shown, a calibration method 800 for a current sensor (hereinafter referred to as calibration method 800) includes the following steps:

[0072] Step S801: outputting a constant current.

[0073] Step S802: dividing the constant current and outputting a first voltage, and outputting the divided test current to the current sensor.

[0074] Step S803: receiving a first voltage and a second voltage from a current sensor, wherein the second voltage reflects a test current flowing through the current sensor.

[0075] Step S804: calibrating the current sensor according to the constant current, the first voltage, and the second voltage.

[0076] In step S802, a constant current may be divided by a sensing device to output a first voltage. The sensing device has a first current range, and the current sensor has a second current range, where the first current range is smaller than the second current range. In some embodiments, the sensing device includes a shunt resistor, and the current sensor includes a Hall effect sensor or a shunt resistor.

[0077] In step S804, the step of calibrating the current sensor according to the constant current, the first voltage, and the second voltage includes:

[0078] A test current value A2 of the test current is calculated based on the first voltage and the resistance of the sensor device. A detection current value A3 of the test current flowing through the current sensor is calculated based on the second voltage and the resistance of the current sensor. The current value of the constant current is recorded as the constant current value A1. The current sensor is calibrated according to the following rules. It is determined whether the ratio of the test current value A2 to the constant current value A1 and the ratio of the test current value A2 to the detection current value A3 satisfy the following formula:

[0079] |A2 / A1-1|<T and |A2 / A3-1|<T

[0080] Where T is the current accuracy value, and the current accuracy value can be set as needed. Taking T as 0.1 as an example, |A2 / A1-1|<0.1 and |A2 / A3-1|<0.1, then the range of A2 / A1 is in the range of 0.9~1.1, and the range of A2 / A3 is also in the range of 0.9~1.1, and the above formula is valid. If the ratio of the test current value A2 to the constant current value A1 and the ratio of the test current value A2 to the detection current value A3 meet the above formula, then the ratio of the test current value A2 to the detection current value A3 is used as the calibration coefficient of the current sensor. The calibration formula of the current sensor is as follows:

[0081] I0=(A2 / A3)*I3

[0082] Where I3 is the current value measured by the current sensor when the switch S is closed, and I0 is the current value after the current sensor is calibrated.

[0083] In some embodiments, the calibration method 800 also includes diagnosing a fault of the sensor device based on the constant current value and the test current value. If the ratio of the test current value to the constant current value is less than a first threshold value, the fault of the sensor device is diagnosed as a short circuit. If the test current value is fully deviated, the fault of the sensor device is diagnosed as an open circuit.

[0084] The calibration method for a current sensor of the present invention calibrates the current sensor by providing a high-precision test current for the current sensor, thereby improving the precision of the current sensor.

[0085] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosures are merely illustrative and do not constitute limitations on this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0086] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0087] Some aspects of the present application can be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software can be referred to as "data blocks", "modules", "engines", "units", "components" or "systems". The processor can be one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors or combinations thereof. In addition, various aspects of the present application may be expressed as computer products located in one or more computer-readable media, which include computer-readable program code. For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, tapes...), optical disks (e.g., compact disks CDs, digital versatile disks DVDs...), smart cards, and flash memory devices (e.g., cards, sticks, key drives...).

[0088] Similarly, it should be noted that, in order to simplify the presentation of this application and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single embodiment disclosed above.

[0089] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0090] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A calibration system for a current sensor, characterized in that: It includes a control module, a constant current module, a sensor device, a first feedback module and a second feedback module; The control module is connected to the constant current module, and the control module is used to configure the constant current module to output a constant current; The sensing device is connected in series to the output end of the constant current module, and is used to divide the constant current and output a first voltage, and to output the divided test current to the current sensor; The first feedback module is connected to the sensor device and the control module respectively, and is used to receive the first voltage and send the first voltage to the control module; The second feedback module is connected to the current sensor and the control module respectively, and is used to receive a second voltage from the current sensor and send the second voltage to the control module, wherein the second voltage reflects the test current flowing through the current sensor; The control module is further configured to receive the first voltage and the second voltage, and calibrate the current sensor according to the constant current, the first voltage, and the second voltage; In which, the control module is configured to calculate the test current value of the test current based on the first voltage, calculate the detection current value of the test current flowing through the current sensor based on the second voltage, and diagnose the fault of the sensing device based on the constant current value and the test current value. If the ratio of the test current value to the constant current value is less than a first threshold value, the fault of the sensing device is diagnosed as a short circuit; if the test current value is fully deviated, the fault of the sensing device is diagnosed as an open circuit.

2. The calibration system according to claim 1, wherein: The sensing device has a first current range, and the current sensor has a second current range, wherein the first current range is smaller than the second current range.

3. The calibration system according to claim 2, wherein: The sensing device is a shunt resistor, and the current sensor is a Hall sensor or a shunt resistor.

4. The calibration system according to claim 1, wherein: The constant current module includes: triode; a sampling resistor connected to the collector of the transistor; a voltage stabilizer connected to the sampling resistor and configured to provide a voltage to the sampling resistor; an operational amplifier circuit connected in parallel with the sampling resistor, configured to amplify the voltage across the sampling resistor to obtain an amplified voltage, and transmit the amplified voltage; A linear constant voltage and constant current driver chip is connected to the base of the transistor, and is used to receive the amplified voltage and control the emitter of the transistor to output the constant current according to the amplified voltage.

5. The calibration system according to claim 1, wherein: The first feedback module includes a first AD sampling circuit and a first isolation circuit, the first AD sampling circuit is connected to the sensing device, and the first isolation circuit is connected to the control module; the second feedback module includes a second AD sampling circuit and a second isolation circuit, the second AD sampling circuit is connected to the current sensor, and the second isolation circuit is connected to the control module.

6. The calibration system according to claim 1, wherein: The control module calibrating the current sensor according to the constant current, the first voltage, and the second voltage includes: Calculate the ratio among the test current value, the detection current value and the constant current value of the constant current; if the ratio of the test current value to the constant current value and the ratio of the test current value to the detection current value are both within the first interval, use the ratio of the test current value to the detection current value as the calibration coefficient of the current sensor.

7. The calibration system according to claim 6, wherein: The control module is also configured to determine whether the current sensor and the second feedback module are faulty based on the test current value and the detection current value; if the detection current value is zero or the ratio of the test current value to the detection current value exceeds the first interval, the current sensor and the second feedback module are faulty.

8. The calibration system according to claim 1, wherein: It also includes a current lead-out line for leading the test current to the current sensor.

9. The calibration system according to claim 1, wherein: It also includes a digital isolator located between the control module and the constant current module, and is used to isolate the current between the control module and the constant current module.

10. A calibration method for a current sensor, characterized in that: include: Output constant current; Dividing the constant current and outputting a first voltage, and outputting the divided test current to the current sensor; receiving the first voltage and a second voltage from the current sensor, wherein the second voltage reflects the test current flowing through the current sensor; as well as calibrating the current sensor according to the constant current, the first voltage, and the second voltage; A test current value is calculated based on the first voltage, a detection current value is calculated based on the second voltage, and a fault of the sensor device is diagnosed based on the constant current value and the test current value. If the ratio of the test current value to the constant current value is less than a first threshold value, the fault of the sensor device is diagnosed as a short circuit. If the test current value is fully deviated, the fault of the sensor device is diagnosed as an open circuit, wherein the constant current is divided by the sensor device and a first voltage is output.

11. The calibration method according to claim 10, wherein: Calibrating the current sensor according to the constant current, the first voltage, and the second voltage includes: Calculate the ratio among the test current value, the detection current value and the constant current value of the constant current; if the ratio of the test current value to the constant current value and the ratio of the test current value to the detection current value are both within the first interval, use the ratio of the test current value to the detection current value as the calibration coefficient of the current sensor.

12. The calibration method according to claim 11, wherein: The sensing device has a first current range, and the current sensor has a second current range, wherein the first current range is smaller than the second current range.

13. The calibration method according to claim 12, wherein: The sensing device is a shunt resistor, and the current sensor is a Hall sensor or a shunt resistor.

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