CN114895230A - Calibration system and method for current sensors - Google Patents
Calibration system and method for current sensors Download PDFInfo
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- CN114895230A CN114895230A CN202210519353.7A CN202210519353A CN114895230A CN 114895230 A CN114895230 A CN 114895230A CN 202210519353 A CN202210519353 A CN 202210519353A CN 114895230 A CN114895230 A CN 114895230A
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Abstract
The invention provides a calibration system and method for a current sensor. The system comprises a control module, a constant current module, a sensing device, a first feedback module and a second feedback module. The control module is connected with the constant current module and is used for configuring the constant current module to output constant current; the sensing device is connected in series with the output end of the constant current module, and is used for dividing the constant current and outputting a first voltage and outputting a divided test current to the current sensor; the first feedback module is used for receiving the first voltage and sending the first voltage to the control module; the second feedback module is used for receiving a second voltage from the current sensor and sending the second voltage to the control module; the control module is further configured to receive the first voltage and the second voltage and calibrate the current sensor based on the constant current, the first voltage, and the second voltage. The invention improves the accuracy of the current sensor and the cost of the whole calibration system is lower.
Description
Technical Field
The present invention relates generally to the field of battery management, and more particularly to a calibration system and method for a current sensor.
Background
The current power battery management system mainly adopts the following two current sensors to sample current. One is a hall type current sensor that indirectly measures the magnitude of current in a wire by measuring the intensity of magnetic field in the vicinity of the current. The Hall type current sensor is used for non-contact measurement and can measure a larger current value, but the measurement precision is low and the temperature drift is large. The other is a shunt resistance type current sensor which is connected in a loop in series, and the current in the lead is indirectly measured by measuring the voltage at two ends of a shunt resistor.
Because the high-current shunt resistance type current sensor and the high-current Hall type current sensor are generally higher in cost, a plurality of manufacturers only use a single high-current shunt resistance type current sensor or a single high-current Hall type current sensor to perform current sampling, and the accuracy requirement that the sampling error of a single cluster of current in a battery management system is not higher than 0.2% in the national standard GBT 34131 and 2017 cannot be met.
Therefore, a low-cost and high-precision calibration system for calibrating the current sensor in the battery management system is needed.
Disclosure of Invention
The present invention is directed to solving the above problems and providing a calibration system and method for a current sensor.
In order to solve the technical problem, the invention provides a calibration system for a current sensor, which comprises a control module, a constant current module, a sensing device, a first feedback module and a second feedback module, wherein the control module is used for controlling the constant current module to work; the control module is connected with the constant current module and is used for configuring the constant current module to output a constant current; the sensing device is connected in series with the output end of the constant current module, and is used for dividing the constant current and outputting a first voltage and outputting a divided test current to the current sensor; the first feedback module
-1-connected to said sensing means and to said control module, respectively, said first feedback module being adapted to receive said first voltage and to send it to said control module; the second feedback module is respectively connected with the current sensor and the control module, and is used for receiving a second voltage from the current sensor and sending 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 based on the constant current, the first voltage, and the second voltage.
In one embodiment of the present invention, the sensing device has a first current measurement range and the current sensor has a second current measurement range, the first current measurement range being less than the second current measurement range.
In an embodiment of the present invention, the sensing device is a shunt resistor, and the current sensor is a hall sensor or a shunt resistor.
In an embodiment of the present invention, the constant current module includes: a triode; the sampling resistor is connected with the collector of the triode; the voltage stabilizer is connected with the sampling resistor and is used for providing voltage for the sampling resistor; the operational amplifier circuit is connected with the sampling resistor in parallel and used for amplifying the voltage at two ends of the sampling resistor to obtain an amplified voltage and sending the amplified voltage; and the linear constant-voltage constant-current driving chip is connected with the base electrode of the triode and used for receiving the amplified voltage and controlling the emitter of the triode to output the constant current according to the amplified voltage.
In an 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 comprises a second AD sampling circuit and a second isolation circuit, the second AD sampling circuit is connected with the current sensor, and the second isolation circuit is connected with the control module.
In an embodiment of the present invention, the control module calibrating the current sensor according to the constant current, the first voltage, and the second voltage includes: 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 a ratio between the test current value, the detection current value, and a constant current value of the constant current, and use the ratio between the test current value and the detection current value as a calibration coefficient of the current sensor if the ratio between the test current value and the constant current value and the ratio between the test current value and the detection current value are within a first interval.
In an embodiment of the present invention, the control module is further configured to determine whether the current sensor and the second feedback module have a fault according to the test current value and the detected current value, and if the detected current value is zero or a ratio of the test current value to the detected current value exceeds the first interval, the current sensor and the second feedback module have a fault.
In an embodiment of the present invention, the control module is further configured to diagnose a fault of the sensing device according to the constant current value and the test current value, and if a ratio of the test current value to the constant current value is smaller than a first threshold, diagnose the fault of the sensing device as a short circuit, and if the test current value is biased fully, diagnose the fault of the sensing device as an open circuit.
In an embodiment of the invention, the test circuit further comprises a current lead-out wire for leading out the test current to the current sensor.
In an embodiment of the present invention, the present invention further includes a digital isolator, located between the control module and the constant current module, for isolating a current between the control module and the constant current module.
Another aspect of the present invention also provides a calibration method for a current sensor, including: outputting a 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; and calibrating the current sensor according to the constant current, the first voltage and the second voltage.
In an embodiment of the present invention, calibrating the current sensor based on the constant current, the first voltage, and the second voltage comprises: calculating a test current value according to the first voltage; calculating a detection current value according to the second voltage; and calculating the ratio of the test current value to the constant current value of the constant current, and taking the ratio of the test current value to the detection current value as the calibration coefficient of the current sensor 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 in a first interval.
In one embodiment of the present invention, the constant current is divided by a sensing device and a first voltage is output, 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.
In an embodiment of the present invention, the sensing device is a shunt resistor, and the current sensor is a hall sensor or a shunt resistor.
In an embodiment of the present invention, the method further includes diagnosing a fault of the sensing device according to the constant current value and the test current value, if a ratio of the test current value to the constant current value is smaller than a first threshold, the fault of the sensing device is diagnosed as a short circuit, and if the test current value is biased fully, the fault of the sensing device is diagnosed as a short circuit
-3-the failure of the sensing means is an open circuit.
Compared with the prior art, the invention has the following advantages:
according to the calibration system for the current sensor, the current sensor is calibrated by adding the constant current module and the small-range high-precision sensing device, so that the precision of the current sensor is improved, and the cost of the whole calibration system is low; the independent first feedback module and the independent second feedback module respectively feed back signals, so that the simultaneous failure of two or more modules caused by a certain common reason in a system is avoided; whether the module in the calibration system breaks down or not is judged according to the constant current value, the test current value and the detection current value by configuring the control module, so that the fault module in the calibration system can be quickly positioned, and maintenance of maintenance personnel is facilitated.
Drawings
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below, wherein:
FIG. 1 is a system block diagram of a calibration system for a current sensor according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a constant current module according to an embodiment of the invention;
FIG. 3 is a schematic structural diagram of a first feedback module according to an embodiment of the invention;
fig. 4 is a circuit diagram of an AD sampling circuit according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a second feedback module according to an embodiment of the invention;
fig. 6 is a circuit diagram of an AD sampling circuit according to an embodiment of the present invention;
FIG. 7 is a system block diagram of a calibration system for a current sensor according to another embodiment of the present invention;
FIG. 8 is a flow chart of a calibration method for a current sensor according to an embodiment of the invention.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only examples or embodiments of the application, from which the application can also be applied to other similar scenarios without inventive effort for a person skilled in the art. Unless otherwise apparent from the context, or otherwise indicated, like reference numbers in the figures refer to the same structure or operation.
As shown in the present application and claims, unless the context clearly dictates otherwise, "a" or "an" ("means one or two),
The terms "4", "a", "an" and/or "the" do not denote a singular but may include a plural. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the case of not making a reverse description, these directional terms do not indicate and imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the scope of the present application; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "above … … surface," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and if not otherwise stated, the terms are not particularly limited
The meaning of-5-and therefore should not be understood as limiting the scope of protection of the present application. Further, although the terms used in the present application are selected from publicly known and used terms, some of the terms mentioned in the specification of the present application may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Further, it is required that the present application is understood not only by the actual terms used but also by the meaning of each term lying within.
It will be understood that when an element is referred to as being "on," "connected to," "coupled to" or "contacting" another element, it can be directly on, connected or coupled to, or contacting the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly on," "directly connected to," "directly coupled to" or "directly contacting" another element, there are no intervening elements present. Similarly, when a first component is said to be "in electrical contact with" or "electrically coupled to" a second component, there is an electrical path between the first component and the second component that allows current to flow. The electrical path may include capacitors, coupled inductors, and/or other components that allow current to flow even without direct contact between the conductive components.
Flow charts are used herein to illustrate 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 the exact order in which they are performed. Rather, various steps may be processed in reverse order or simultaneously. Meanwhile, other operations are added to or removed from these processes.
FIG. 1 is a system block diagram of a calibration system 100 for a current sensor in accordance with an embodiment of the present invention. As shown in fig. 1, the current sensor to be calibrated in this embodiment is a SHUNT resistance type current sensor 1, labeled SHUNT in fig. 1. When the shunt resistance type current sensor 1 is shipped or needs calibration, the switch S is turned off, and the calibration system 100 for the current sensor (hereinafter referred to as the calibration system 100) of the present embodiment calibrates the shunt resistance type current sensor. 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 connection. The control module 11 is configured to configure the constant current module 12 to output a constant current I1. The sensing device 13 is connected in series to an output end of the constant current module 12, and the sensing device 13 is configured to divide the constant current I1 and output a first voltage V1, and is configured to output a divided test current I2 to the shunt resistance type 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 configured 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 resistance type current sensor 1 and the control module 11 respectively. Second feedback module 15
-6-for receiving a second voltage V2 from the shunt resistive current sensor 1 and sending a second voltage V2 to the control module 11, wherein the second voltage V2 reflects the test current I2 flowing through the shunt resistive current sensor 1; the control module 11 is further configured to receive the first voltage V1 and the second voltage V2, and calibrate the shunt resistive current sensor 1 according to the constant current I1, the first voltage V1, and the second voltage V2.
With continued reference to fig. 1, in the present embodiment, the sensing device 13 is a shunt resistance type current sensor. Sensing device 13 differs from shunt resistive current sensor 1 in that sensing device 13 has a first current range and shunt resistive current sensor 1 has a second current range, the first current range being less than the second current range. That is, the shunt resistance type current sensor 1 can measure a large current value, and the sensing device 13 can only measure a small current value. Just as the current range of the sensing device 13 is smaller than the current range of the shunt resistance type current sensor 1, the cost of the sensing device 13 is lower than the cost of the shunt resistance type current sensor 1.
In some embodiments, the control module 11 calibrating the shunt resistive current sensor 1 according to the constant current I1, the first voltage V1, and the second voltage V2 includes: the control module 11 is configured to calculate a test current value A2 of the test current I2 according to the first voltage V1 and the resistance value of the sensing device 13. The detection current value A3 of the test current I2 flowing through the shunt resistance type current sensor 1 is calculated according to the second voltage V2 and the resistance value of the shunt resistance type current sensor 1. The current value of the constant current I1 was recorded as a constant current value a 1. The control module 11 is configured to calibrate the shunt resistance type current sensor 1 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 equations:
i A2/A1-1I < T and I A2/A3-1I < T
Wherein T is a current precision value, and the magnitude of the current precision value can be set as required. When T is 0.1, if | A2/A1-1| < 0.1 and | A2/A3-1| < 0.1, the range of A2/A1 is in the range of 0.9 to 1.1, and the range of A2/A3 is also in the range of 0.9 to 1.1, the above formula holds. 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 satisfy the above equations, the ratio of the test current value a2 to the detection current value A3 is used as the calibration coefficient of the shunt resistance type current sensor 1, and the calibration equation of the shunt resistance type current sensor 1 is as follows:
I 0 ＝(A2/A3)*I3
wherein I3 is the current value measured by the resistance type current sensor 1 when the switch S is closed, I 0 The current value after calibration of the shunt resistance type current sensor 1.
Fig. 2 is a circuit diagram of the constant current module 12 according to an embodiment of the present invention. The constant current module 12 comprises a linear constant
The circuit comprises a 7-voltage constant current driving chip U2, a triode Q1, a voltage stabilizer U11, a sampling resistor R2 and an operational amplifier circuit U10. The sampling resistor R2 is connected with the collector of the triode Q1, the voltage stabilizer U11 is connected with the sampling resistor R2, and the voltage stabilizer U11 is used for supplying voltage to the sampling resistor R2. In the present embodiment, regulator U11 has a model number TLV 752. The voltage regulator U11 is configured to step down the 5V isolation voltage provided by the power supply to 1.1V, and then provide the 1.1V voltage to the sampling resistor R2. The operational amplifier circuit U10 is connected in parallel with the sampling resistor R2 and is used for amplifying the voltage at the two ends of the sampling resistor R2 to obtain an amplified voltage FB and sending the amplified voltage FB to the linear constant-voltage constant-current driving chip U2. The amplification times of the operational amplifier circuit U10 to the voltage at the two ends of the sampling resistor R2 can be 50 times, and can also be other times, and the amplification times are not limited in the application. The linear constant-voltage constant-current driving chip U2 is connected with the base of the triode Q1 and is used for receiving the amplified voltage FB and controlling the triode Q1 to be in a linear working area according to the amplified voltage FB, so that the emitter of the triode Q1 outputs a constant current I1. In fig. 2, the sensing device is a resistor R1, and the constant current I1 is divided into two end voltages I through a resistor R1 2 OUT + and I 2 OUT. In this embodiment, the sampling resistor R2 has a resistance of 0.1 ohm, and the constant current module 12 outputs current according to the following formula:
I1＝1A*DPWM
the DPWM is a duty ratio of a Pulse Width Modulation (PWM) signal, that is, the constant current I1 can be implemented by PWM programming in a range of 0 to 1A.
Fig. 3 is a schematic structural diagram of a first feedback module according to an embodiment of the present invention. As shown in fig. 3, 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 sensing 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 the first voltage V1 across the sensing device 13 and send 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.
Fig. 4 is a circuit diagram of the AD sampling circuit 141 according to an embodiment of the present invention. As shown in fig. 4, the AD sampling circuit 141 includes a current monitor U3 and a matching component that implements the function of the current monitor U3. In this embodiment, current monitor U3 is model INA226 AIDGSR. The INA226AIDGSR is a current divider and power supply monitor with a PC interface. The current monitor U3 receives I 2 OUT + and I 2 Voltage drop between _ OUT, pair I 2 OUT + and I 2 The voltage drop between OUT is analog-to-digital converted and the converted value is then sent to an isolation circuit (not shown) via SDA and SCKL of the current monitor U3.
Fig. 5 is a schematic structural diagram of a second feedback module according to an embodiment of the present invention. As shown in fig. 5, in one
8-in some embodiments, the second feedback module 15 comprises an AD sampling circuit 151 and a digital isolator 152. The sampling circuit 151 is connected to the shunt resistance type current sensor 1, and the isolation circuit 152 is connected to the control module 11. The AD sampling circuit 151 is configured to perform analog-to-digital conversion on the second voltage V2 across the shunt resistance type current sensor 1 and send the converted second voltage to the isolation circuit 152. The isolation circuit 152 receives the converted second voltage V2 and transmits the converted second voltage V2 to the control module 11 via the I2C bus 110.
Fig. 6 is a circuit diagram of the AD sampling circuit 151 according to an embodiment of the present invention. As shown in fig. 6, the AD sampling circuit 151 includes a current monitor U5 and a matching component that implements the function of the current monitor U5. In this embodiment, current monitor U5 is model INA226 AIDGSR. The INA226AIDGSR is a current divider and power supply monitor with a PC interface. The current monitor U5 divides the second voltage across the SHUNT-resistance current sensor (i.e., SHUNT) + And SHUNT - Voltage drop therebetween) is analog-to-digital converted and the converted value is then sent to an isolation circuit (not shown) via SDA and SCKL of current monitor U5.
In some embodiments, as shown in fig. 1, the calibration system 100 is disposed inside the battery management system BMS, the calibration system 100 further including a current outlet 16. The current lead 16 is used to lead the test current I2 provided by the sensing device 13 to the shunt resistance type current sensor 1 outside the battery management system BMS.
In some embodiments, as shown in fig. 1, the calibration quasi-system 100 further includes a digital isolator (not shown) located between the control module 11 and the constant current module 12 for isolating current between the control module 11 and the constant current module 12.
In some embodiments, control module 11 is further configured to determine whether a module in calibration system 100 is malfunctioning based on constant current value A1, test current value A2, and sensed current value A3. Taking the current precision value as 0.1 as an example, whether a module in the calibration system 100 fails is determined by the following fault table (table 1).
TABLE 1
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 sensing device 13 fails and the type of failure is a short circuit; if the test current value A2 is fully biased, the sensing 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 within the interval of 0.9-1.1, the constant current module 12 or the first feedback module 14 breaks down; if test current value A2 is equal to zero, then either first feedback module 14 or current lead 16 fails; if the detected current value A3 is equal to zero or the ratio of the detected current value A2 to the detected current value A3 is not within the range of 0.9-1.1, the shunt resistance type current sensor 1 or the second feedback module 15 fails.
FIG. 7 is a system block diagram of a calibration system for a current sensor according to another embodiment of the present invention. As shown in fig. 7, the current sensor to be calibrated in this embodiment is a hall type current sensor 2. When the hall-type current sensor 2 is shipped or needs to be calibrated, the switch S is turned off, and the calibration system 700 for the current sensor (hereinafter referred to as the calibration system 700) of the present embodiment calibrates the current sensor. The calibration system 700 includes a control module 71, a constant current module 72, a sensing device 73, first and second feedback modules 74, 77, and a current outlet 76. The calibration system 700 differs from the calibration system 100 according to the first exemplary embodiment in that the current supply line 76 is not directly connected to the hall current sensor 2. The hall type current sensor 2 includes a magnetic conductive ring and a hall chip. The current lead-out wire 76 passes through the magnetic conductive ring of the hall type current sensor 2, the magnetic conductive ring induces a magnetic field intensity by the current flowing through the current lead-out wire 76, and the hall chip of the hall type current sensor 2 detects the magnetic field intensity in the magnetic conductive ring to obtain a second voltage V2. And the control module 71 is configured to look up a voltage and current correspondence table of the hall type current sensor according to the converted second voltage signal to obtain a detected current value a 3.
According to the calibration system for the current sensor, the current sensor is calibrated by adding the constant current module and the small-range high-precision sensing device, so that the precision of the current sensor is improved, and the cost of the whole calibration system is low; the independent first feedback module and the independent second feedback module respectively feed back signals, so that the simultaneous failure of two or more modules caused by a certain common reason in a system is avoided; whether the module in the calibration system breaks down or not is judged according to the constant current value, the test current value and the detection current value by configuring the control module, so that the fault module in the calibration system can be quickly positioned, and maintenance of maintenance personnel is facilitated.
The invention also provides a calibration method for the current sensor. The calibration method for a current sensor may be performed by the calibration system for a current sensor of any of the embodiments described hereinbefore. Therefore, for a detailed description of the calibration method for the current sensor, reference may be made to the description of the calibration system for the current sensor described above, and the description thereof is omitted here.
FIG. 8 is a flow chart of a calibration method for a current sensor according to an embodiment of the invention. As shown in fig. 8, a calibration method 800 for a current sensor (hereinafter referred to as calibration method 800) includes the steps of:
step S801: and outputting constant current.
Step S802: the constant current is divided and a first voltage is output, and the constant current is used for outputting the divided test current to the current sensor.
Step S803: a first voltage and a second voltage from the current sensor are received, wherein the second voltage reflects a test current flowing through the current sensor.
Step S804: the current sensor is calibrated based on the constant current, the first voltage, and the second voltage.
In step S802, the constant current may be divided by a sensing device and a first voltage may be output, the sensing device having a first current range, the current sensor having a second current range, the first current range being less than the second current range. In some embodiments, the sensing device shunts a resistor and the current sensor is a hall sensor or a shunt resistor.
In step S804, the step of calibrating the current sensor according to the constant current, the first voltage, and the second voltage includes:
a test current value A2 of the test current is calculated according to the first voltage and the resistance value of the sensing device. A detected current value A3 of the test current flowing through the current sensor is calculated according to the second voltage and the resistance value of the current sensor. The current value of the constant current is denoted as a constant current value a 1. 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 detected current value A3 satisfy the following equations:
i A2/A1-1I < T and I A2/A3-1I < T
Wherein T is a current precision value, and the magnitude of the current precision value can be set as required. When T is 0.1, if | A2/A1-1| < 0.1 and | A2/A3-1| < 0.1, the range of A2/A1 is in the range of 0.9 to 1.1, and the range of A2/A3 is also in the range of 0.9 to 1.1, the above formula holds. 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 satisfy the above equations, the ratio of the test current value a2 to the detection current value A3 is used as the calibration coefficient of the current sensor, and the calibration equation of the current sensor is as follows:
I 0 ＝(A2/A3)*I3
where I3 is the current value measured by the current sensor when switch S is closed, I 0 The current value after the current sensor calibration.
In some embodiments, the calibration method 800 further includes diagnosing a fault of the sensing device based on the constant current value and the test current value, diagnosing the fault of the sensing device as a short circuit if a ratio of the test current value to the constant current value is less than a first threshold, and diagnosing the fault of the sensing device as an open circuit if the test current value is biased fully.
The calibration method for the current sensor provided by the invention is used for calibrating the current sensor by providing a high-precision test current for the current sensor, so that the precision of the current sensor is improved.
Having thus described the basic concept, it should be apparent to those skilled in the art that the foregoing disclosure is by way of example only, and is not intended to limit the present application. Various modifications, improvements and adaptations to the present application may occur to those skilled in the art, although not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present application and thus fall within the spirit and scope of the exemplary embodiments of the present application.
Also, this application uses specific language to describe embodiments of the application. Reference throughout this specification to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the present application is included in at least one embodiment of the present application. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.
Aspects of the present application may be embodied entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) or in a combination of hardware and software. The above hardware or software may be referred to as "data block," module, "" engine, "" unit, "" component, "or" system. The processor may 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 a combination thereof. Furthermore, aspects of the present application may be represented as a computer product, including computer readable program code, embodied in one or more computer readable media. For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips … …), optical disks (e.g., Compact Disk (CD), Digital Versatile Disk (DVD) … …), smart cards, and flash memory devices (e.g., card, stick, key drive … …).
Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to require more features than are expressly recited in the claims. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.
Numerals describing the number of components, attributes, etc. are used in some embodiments, it being understood that such numerals used in the description of the embodiments are modified in some instances by the use of the modifier "about", "approximately" or "substantially". Unless otherwise indicated, "about", "approximately" or "substantially" indicates that the number allows a variation of ± 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending upon the desired properties of the individual embodiments. In some embodiments, the numerical parameter should take into account the specified significant digits and employ a general digit preserving approach. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the range are approximations, in the specific examples, such numerical values are set forth as precisely as possible within the scope of the application.
Although the present application has been described with reference to the present specific embodiments, it will be recognized by those skilled in the art that the foregoing embodiments are merely illustrative of the present application and that various changes and substitutions of equivalents may be made without departing from the spirit of the application, and therefore, it is intended that all changes and modifications to the above-described embodiments that come within the spirit of the application fall within the scope of the claims of the application.
Claims (15)
1. A calibration system for a current sensor is characterized by 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 with the constant current module and is used for configuring the constant current module to output a constant current;
the sensing device is connected in series with the output end of the constant current module, and is used for dividing the constant current and outputting a first voltage and outputting a divided test current to the current sensor;
the first feedback module is respectively connected with the sensing device and the control module, and is used for receiving the first voltage and sending the first voltage to the control module;
the second feedback module is respectively connected with the current sensor and the control module, and is used for receiving a second voltage from the current sensor and sending 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 based on the constant current, the first voltage, and the second voltage.
2. The calibration system of claim 1 wherein said sensing device has a first current measurement range and said current sensor has a second current measurement range, said first current measurement range being less than said second current measurement range.
3. The calibration system of 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 of claim 1, wherein the constant current module comprises:
a triode;
the sampling resistor is connected with the collector of the triode;
the voltage stabilizer is connected with the sampling resistor and is used for providing voltage for the sampling resistor;
the operational amplifier circuit is connected with the sampling resistor in parallel and used for amplifying the voltage at two ends of the sampling resistor to obtain an amplified voltage and transmitting the amplified voltage;
and the linear constant-voltage constant-current driving chip is connected with the base electrode of the triode and used for receiving the amplified voltage and controlling the emitter of the triode to output the constant current according to the amplified voltage.
5. The calibration system of claim 1, wherein the first feedback module comprises a first AD sampling circuit and a first isolation circuit, the first AD sampling circuit coupled to the sensing device, the first isolation circuit coupled to the control module; the second feedback module comprises a second AD sampling circuit and a second isolation circuit, the second AD sampling circuit is connected with the current sensor, and the second isolation circuit is connected with the control module.
6. The calibration system of claim 1, wherein the control module calibrating the current sensor based on the constant current, the first voltage, and the second voltage comprises:
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 a ratio between the test current value, the detection current value, and a constant current value of the constant current, and use the ratio between the test current value and the detection current value as a calibration coefficient of the current sensor if the ratio between the test current value and the constant current value and the ratio between the test current value and the detection current value are within a first interval.
7. The calibration system of claim 6, wherein the control module is further configured to determine whether the current sensor and the second feedback module are malfunctioning based on the test current value and a detected current value, and the current sensor and the second feedback module are malfunctioning if the detected current value is zero or a ratio of the test current value to the detected current value exceeds the first interval.
8. The calibration system of claim 6, wherein the control module is further configured to diagnose a fault in the sensing device based on the constant current value and the test current value, the fault in the sensing device being diagnosed as a short circuit if a ratio of the test current value to the constant current value is less than a first threshold value, and the fault in the sensing device being diagnosed as an open circuit if the test current value is fully biased.
9. The calibration system of claim 1, further comprising a current lead-out for leading out the test current onto the current sensor.
10. The calibration system of claim 1, further comprising a digital isolator between the control module and the constant current module for isolating current between the control module and the constant current module.
11. A calibration method for a current sensor, comprising:
outputting a 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; and
calibrating the current sensor based on the constant current, the first voltage, and the second voltage.
12. The calibration method of claim 11, wherein calibrating the current sensor based on the constant current, the first voltage, and the second voltage comprises:
calculating a test current value according to the first voltage;
calculating a detection current value according to the second voltage;
and calculating the ratio of the test current value to the constant current value of the constant current, and taking the ratio of the test current value to the detection current value as the calibration coefficient of the current sensor 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 in a first interval.
13. The calibration method of claim 12 wherein the constant current is divided by a sensing device and outputs a first voltage, the sensing device having a first current range and the current sensor having a second current range, the first current range being less than the second current range.
14. The calibration method of claim 13, wherein the sensing device is a shunt resistor and the current sensor is a hall sensor or a shunt resistor.
15. The calibration method of claim 13, further comprising diagnosing a fault in the sensing device based on the constant current value and the test current value, wherein the fault in the sensing device is a short circuit if a ratio of the test current value to the constant current value is less than a first threshold value, and wherein the fault in the sensing device is an open circuit if the test current value is biased.
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