CN116184294A - Trimming system of current sensor - Google Patents
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- CN116184294A CN116184294A CN202310274870.7A CN202310274870A CN116184294A CN 116184294 A CN116184294 A CN 116184294A CN 202310274870 A CN202310274870 A CN 202310274870A CN 116184294 A CN116184294 A CN 116184294A
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- 238000009966 trimming Methods 0.000 title claims abstract description 123
- 239000007788 liquid Substances 0.000 claims abstract description 101
- 238000012360 testing method Methods 0.000 claims abstract description 41
- 238000010438 heat treatment Methods 0.000 claims description 28
- 238000012546 transfer Methods 0.000 claims description 22
- 238000001816 cooling Methods 0.000 claims description 21
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- 238000005070 sampling Methods 0.000 claims description 15
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- 238000005057 refrigeration Methods 0.000 claims description 3
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- 238000005516 engineering process Methods 0.000 description 5
- 238000004378 air conditioning Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
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Abstract
The invention discloses a trimming system of a current sensor, which comprises an oven, a power supply, an acquisition circuit and an upper computer. The oven comprises a test tank, wherein the test tank is used for containing liquid with target temperature, and a standard current sensor and a target current sensor to be modified which are immersed in the liquid; the power supply is used for providing current to be measured for the standard current sensor and the target current sensor; the acquisition circuit is used for acquiring a first output voltage of the standard current sensor and a second output voltage of the target current sensor when the current to be detected passes through the standard current sensor and the target current sensor; the upper computer is used for determining trimming parameters of the target current sensor at the target temperature according to the first output voltage and the second output voltage acquired by the acquisition circuit. The trimming precision is high.
Description
Technical Field
The invention relates to the technical field of sensor calibration, in particular to a trimming system of a current sensor.
Background
Before the current sensor leaves the factory, the current sensor can be trimmed to ensure the accuracy of the measurement result. The trimming process of the current sensor refers to presetting trimming parameters in the current sensor to correct the measurement result of the current sensor. In general, in the current sensor, different temperature intervals correspond to different trimming parameters, which requires that the current sensor be placed at different ambient temperatures during trimming of the current sensor to obtain trimming parameters of the current sensor in different temperature intervals.
At present, in order to improve trimming efficiency, a plurality of current sensors are placed at the same ambient temperature for trimming, that is, the current sensors are trimmed in batches. In some technologies, after the ambient temperature of each current sensor reaches a set temperature by using an air cooling technology, batch trimming is performed on the current sensors. However, when the air cooling technology is used for increasing/decreasing the temperature, the circulating air cannot be blown to the current sensors at all positions, so that the temperatures of the current sensors at different positions are different, and the trimming precision is poor.
Disclosure of Invention
In view of this, the embodiment of the invention provides a trimming system for a current sensor, which can improve trimming accuracy of the current sensor.
The invention provides a trimming system of a current sensor, which comprises:
an oven comprising a test tank for containing a liquid having a target temperature, and a standard current sensor and a target current sensor to be trimmed immersed in the liquid;
the power supply is used for providing current to be measured for the standard current sensor and the target current sensor;
the acquisition circuit is used for acquiring a first output voltage of the standard current sensor and a second output voltage of the target current sensor when the current to be detected passes through the standard current sensor and the target current sensor;
and the upper computer is used for determining the trimming parameters of the target current sensor at the target temperature according to the first output voltage and the second output voltage acquired by the acquisition circuit.
In some embodiments, the oven further comprises a cooling device and a heating device, wherein:
the refrigerating device is used for cooling the liquid when the temperature of the liquid is higher than the target temperature so that the temperature of the liquid reaches the target temperature;
the heating device is used for heating the liquid when the temperature of the liquid is lower than the target temperature so as to enable the temperature of the liquid to reach the target temperature.
In some embodiments, the refrigerating device comprises a compressor, wherein the compressor is respectively connected with the test tank and the upper computer, and is used for cooling the liquid in the test tank to the target temperature based on the control of the upper computer.
In some embodiments, the compressor includes a first compressor and a second compressor connected to the first compressor, the first compressor and the second compressor are respectively connected to the upper computer, the second compressor is connected to the test tank, and the first compressor and the second compressor are used for cooling the liquid in the test tank to the target temperature based on control of the upper computer.
In some embodiments, the heating device comprises a heating component, wherein the heating component is respectively connected with the test groove and the upper computer and is used for heating the liquid in the test groove to the target temperature based on the control of the upper computer.
In some embodiments, the oven further comprises a transfer tank, the test tank comprises a liquid inlet and a liquid outlet, the transfer tank is connected with the liquid inlet and the liquid outlet, the liquid in the test tank is injected into the transfer tank through the liquid outlet, the refrigerating device cools the liquid in the transfer tank to the target temperature, or the heating device heats the liquid in the transfer tank to the target temperature, and then the liquid in the transfer tank is injected into the test tank through the liquid inlet.
In some embodiments, the power supply is specifically configured to provide alternating current to the standard current sensor and the target current sensor as the current to be measured;
the acquisition circuit is specifically used for acquiring the first output voltage of the standard current sensor and the second output voltage of the target current sensor according to the same sampling frequency;
the upper computer is specifically configured to fit the first output voltage and the second output voltage to obtain a fitting result, and determine a trimming parameter of the target current sensor at the target temperature based on the fitting result and the characteristic parameter of the standard current sensor.
In some embodiments, the power supply is specifically configured to provide alternating current at a first frequency to the standard current sensor and the target current sensor;
the acquisition circuit is specifically configured to acquire the first output voltage and the second output voltage according to a sampling frequency of a second frequency;
wherein the first frequency is less than the second frequency.
In some embodiments, the characteristic parameter of the standard current sensor comprises a first zero output voltage, and the trimming parameter of the target current sensor comprises a zero output trimming parameter;
the upper computer is specifically configured to determine a second zero output voltage of the target current sensor in a current detection process based on the fitting result and the first zero output voltage, and determine a zero output trimming parameter of the target current sensor according to a difference between the target zero output voltage required by the target current sensor and the second zero output voltage.
In some embodiments, the characteristic parameter of the standard current sensor comprises a first gain, and the trimming parameter of the target current sensor comprises a gain trimming parameter;
the upper computer is specifically configured to determine a second gain of the target current sensor in a current detection process based on the fitting result and the first gain, and determine a gain trimming parameter of the target current sensor according to a difference between a target gain required by the target current sensor and the second gain.
In the technical solutions of some embodiments of the present application, when the standard current sensor and the target current sensor are immersed in a liquid having a target temperature, since the liquid temperatures at different positions are uniform, the ambient temperatures where the respective current sensors are located are uniform. Therefore, when the target current sensor is trimmed, the influence of the inconsistency of the ambient temperature among the sensors can be reduced, and the trimming precision of the target current sensor can be improved.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and should not be construed as limiting the invention in any way, in which:
FIG. 1 is a schematic diagram of some current sensors for current detection;
FIG. 2 shows a block diagram of a trimming system provided in one embodiment of the present application;
FIG. 3 shows a schematic block diagram of the oven of FIG. 2;
FIG. 4 shows a schematic diagram of the component connections of an oven provided in one embodiment of the present application;
FIG. 5 shows a schematic diagram of the component connections of an oven provided in another embodiment of the present application;
FIG. 6 shows a schematic diagram of the component connections of an oven provided in another embodiment of the present application;
FIG. 7 is a block diagram of a trimming system according to another embodiment of the present application;
fig. 8 is a schematic diagram illustrating connection between a trimming switching circuit and an acquisition circuit according to an embodiment of the present disclosure;
FIG. 9 is a schematic diagram illustrating a connection between a trimming switching circuit and a target current sensor according to an embodiment of the present disclosure;
FIG. 10 illustrates a schematic diagram of the magnitude of alternating current provided by one embodiment of the present application over time;
FIG. 11 shows a schematic representation of a fitted curve provided by an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which a person skilled in the art would obtain without making any inventive effort, are within the scope of the invention.
Fig. 1 is a schematic diagram of some current sensors for current detection. The current sensor may be connected in series in a circuit of the magnitude of the current to be detected. Thus, the current of the current sensor is the same as the current of the circuit to be collected, and when the current of the current sensor is detected, the current of the circuit to be collected is detected.
The current magnitude of the current sensor can be reflected by the output voltage of the current sensor. Specifically, the output voltage of the current sensor may be in a corresponding relationship with the current magnitude of the current sensor. For example, when the output voltage of the current sensor is 2.5 volts, the current of the current sensor is 0 ampere; when the output voltage of the current sensor is 3 volts, the current of the current sensor is 1.5 amperes. Therefore, after the output voltage of the current sensor is detected by the acquisition circuit, the current of the current sensor can be correspondingly determined, and the circuit size in the circuit to be acquired can be determined.
However, in the use process of the current sensor, the output voltage of the current sensor is affected by temperature, so that the detection accuracy of the current sensor is not high. For example, assuming that, in theory, the current sensor has a current level of 0.5 ampere, the output voltage corresponding to the current sensor is 2.7 volts. Thus, when the output voltage of the current sensor is detected to be 2.7 volts, the current of the current sensor can be correspondingly estimated to be 0.5 ampere. However, in practical use, under the condition of 20 ℃, the current of the current sensor is 0.5 ampere hour, and the output voltage can be 2.6 volts; at 30 degrees celsius, the current sensor current level is 0.5 ampere, and the output voltage may be 2.8 volts. That is, the output voltage of the current sensor does not correspond to the theoretical current level due to the influence of temperature, so that the current level estimated from the output voltage of the current sensor is not high in accuracy.
In view of this, the current sensor is usually trimmed before the current sensor is put into service. The trimming process is to set trimming coefficients corresponding to each temperature interval for the current sensor. The trimming coefficient is used for trimming the output voltage of the current sensor, so that the current sensor outputs voltage with the corresponding magnitude with the current. Table 1 exemplarily shows the correspondence between the temperature interval and the trimming coefficient.
TABLE 1 correspondence between temperature intervals and trimming coefficients
| Temperature interval | Trimming coefficient | |
| 20-21 DEG | Trimming coefficient | 1 |
| 21-22 DEG | Trimming coefficient | 2 |
| …… | …… | |
| 29-30 DEG C | Trimming coefficient 11 |
Based on table 1, in each temperature interval, the output voltage of the current sensor can be trimmed based on trimming coefficients corresponding to the temperature interval, so that the current sensor outputs voltage corresponding to the current, and the purpose of improving the detection precision is achieved.
For example, assuming that, in theory, the current sensor has a current level of 0.5 ampere, the output voltage corresponding to the current sensor is 2.7 volts. Then, at 20 degrees celsius, the output voltage of the current sensor can be trimmed based on the trimming coefficient 1, so that the current sensor outputs a voltage of 2.7 volts (if no trimming is performed, the current of the current sensor is 0.5 ampere hour at 20 degrees celsius, and the output voltage may be 2.6 volts). Similarly, at 30 degrees celsius, the output voltage of the current sensor may be trimmed based on the trimming coefficient 11, so that the current sensor outputs a voltage of 2.7 volts (if the trimming is not performed, the current of the current sensor may be 0.5 ampere at 30 degrees celsius, and the output voltage may be 2.8 volts). Therefore, the influence of temperature on the current sensor can be reduced through trimming, and the detection precision of the current sensor is improved.
Currently, when the current sensors are subjected to batch trimming, the ambient temperature of each current sensor is enabled to reach the set temperature through an air cooling technology. However, when the air cooling technology is used for increasing/decreasing the temperature, circulating air cannot be blown to the current sensors at all positions, so that the temperatures of the current sensors at different positions are different, and further the trimming precision is poor.
Therefore, the current sensor trimming system can improve trimming precision. Referring to fig. 2, a schematic block diagram of a trimming system according to an embodiment of the present application is shown. In fig. 2, the trimming system comprises an oven 21, a power supply 22, a collection circuit 23 and an upper computer 24.
In some embodiments, the oven 21 includes a test tank 211, the test tank 211 for holding a liquid 2111 having a target temperature, and a standard current sensor 2112 and a target current sensor 2113 to be trimmed immersed in the liquid 2111. The standard current sensor 2112 may be a current sensor for which trimming has been completed. The output voltage of the standard current sensor 2112 may be temperature independent, i.e., the output voltage of the standard current sensor 2112 corresponds to the current magnitude. The target current sensor 2113 may be a current sensor for which trimming has not been completed. The output voltage of the target current sensor 2113 is affected by temperature, i.e., the output voltage of the target current sensor 2113 and the current magnitude may not correspond exactly. The number of the target current sensors 2113 may be plural. Based on the output voltage of the standard current sensor 2112 and the output voltage of each target current sensor 2113, batch trimming may be performed on the plurality of target current sensors 2112, and a specific trimming process may be referred to in the following related description, which is not repeated herein.
The power supply 22 is used to supply the current to be measured to the standard current sensor 2112 and the target current sensor 2113. The acquisition circuit 23 is configured to acquire a first output voltage of the standard current sensor 2112 and a second output voltage of the target current sensor 2113 when a current to be measured passes through the standard current sensor 2112 and the target current sensor 2113. The upper computer 24 is configured to determine trimming parameters of the target current sensor 2112 at the target temperature according to the first output voltage and the second output voltage acquired by the acquisition circuit 23.
In some embodiments of the present application, when the standard current sensor 2112 and the target current sensor 2113 are immersed in the liquid 2111 having the target temperature, the ambient temperature of each current sensor is uniform because the liquid temperature is uniform at different positions. In this way, when trimming the target current sensor 2113, the influence of the environmental temperature inconsistency between the sensors can be reduced, and the trimming accuracy of the target current sensor 2113 can be improved.
Referring to fig. 3, a schematic block diagram of the oven 21 in fig. 2 is shown. In fig. 3, oven 21 further comprises a cooling device 212 and a heating device 213. The cooling device 212 and the heating device 213 are respectively connected to the test slot 211. The cooling device 212 is configured to cool the liquid 2111 when the temperature of the liquid 2111 is higher than the target temperature, so that the temperature of the liquid 2111 reaches the target temperature. The heating device 213 is configured to raise the temperature of the liquid 2111 to the target temperature when the temperature of the liquid is lower than the target temperature.
Specifically, in some embodiments, a temperature sensor 2114 for sensing the temperature of the liquid is disposed within the test slot 211. The temperature sensor 2114, the cooling device 212, and the heating device 213 are connected to the host computer 24, respectively. The upper computer 24 can determine whether the temperature of the liquid 2111 in the test tank 211 is a target temperature required for trimming according to the temperature detected by the temperature sensor 2114. If the temperature of the liquid 2111 is higher than the target temperature, the upper computer 24 may control the refrigerating device 212 to cool the liquid 2111; if the temperature of the liquid 2111 is lower than the target temperature, the upper computer 24 may control the heating device 213 to raise the temperature of the liquid 2111. Thus, the liquid temperature in the test groove 211 can be adjusted according to the actually required target temperature in the trimming process, and the applicability is good.
Referring to fig. 4, a schematic diagram of the connection of the components of the oven 41 according to one embodiment of the present application is provided.
In some embodiments, the refrigerating apparatus 412 includes a compressor 4121, where the compressor 4121 is connected to the test tank 411 and the host computer 44, respectively, for cooling the liquid 4111 in the test tank 411 to a target temperature based on the control of the host computer 44.
The working principle of the compressor 4121 is similar to that of air conditioning refrigeration, and is not repeated herein. The host computer 44 may control the compression power of the compressor 4121 according to the liquid temperature detected by the temperature sensor 4114, so that the compressor 4121 cools the liquid 4111 to the target temperature.
In some embodiments, the heating device 413 includes a heat generating component 4131, where the heat generating component 4131 is connected to the test slot 411 and the host computer 44, respectively, for heating the liquid 4111 in the test slot 411 to a target temperature based on the control of the host computer 44.
Specifically, the heat generating component 4131 includes, but is not limited to, a heat generating plate, a heat generating tube, and the like. The host computer 44 may control the heating power of the heat generating component 4131 based on the liquid temperature detected by the temperature sensor 4114, so that the heat generating component 4131 heats the liquid 4111 to the target temperature.
The liquid 4111 is cooled by the compressor 4121, and the liquid 4111 is warmed by the heat generating component 4131, and the compressor 4121 and the heat generating component 4131 are components which are easy to obtain, so that the scheme has high feasibility.
Referring to fig. 5, a schematic diagram of connection of components of an oven 51 according to another embodiment of the present application is provided. Fig. 5 and 4 are substantially similar, with the main difference: the compressor 5121 includes a first compressor 5122 and a second compressor 5123 connected to the first compressor 5122, the first compressor 5122 and the second compressor 5123 are respectively connected to the upper computer 54, the second compressor 5123 is connected to the test tank 511, and the first compressor 5122 and the second compressor 5123 are used for cooling the liquid in the test tank 511 to a target temperature based on the control of the upper computer 54. The operation principle of the first compressor 5122 and the second compressor 5123 is similar to that of a two-stage compressor in an air conditioning system, and is not described herein.
Specifically, the upper computer 54 may control the compression power of the first compressor 5122 and the second compressor 5123, respectively, so that the first compressor 5122 and the second compressor 5123 cool the liquid 5111 in the test tank 511 to a target temperature.
In the embodiment shown in fig. 5, two compressors 5121 are used to cool the liquid 5111, so that the liquid 5111 can be cooled to a lower temperature to meet the target temperature required for trimming. The cooling effect is better, and the applicability is stronger.
Referring to fig. 6, a schematic diagram of the connection of the components of the oven 61 according to another embodiment of the present application is provided. Fig. 6 is substantially similar to fig. 5, with the main differences: the oven 61 further comprises a transfer tank 615, the test tank 611 comprises a liquid inlet 6117 and a liquid outlet 6116, the transfer tank 611 is connected with the liquid inlet 6117 and the liquid outlet 6116, liquid 6111 in the test tank 611 is injected into the transfer tank 615 through the liquid outlet 6116, the refrigerating device 612 cools the liquid 6111 in the transfer tank 615 to a target temperature, or the heating device 613 heats the liquid 6111 in the transfer tank 615 to the target temperature, and then the liquid 6111 in the transfer tank 615 is injected into the test tank 611 through the liquid inlet 6117.
Specifically, the heating device 613 may be disposed in the transit tank 615. The second compressor 6123 may be coupled to the staging tank 615. When the liquid 6111 needs to be cooled, the upper computer 64 controls the heating device 613 to stop working and controls the refrigerating device 612 to work so as to cool the liquid 6111 in the transit tank 615 to the target temperature. When the temperature of the liquid 6111 needs to be raised, the upper computer 64 can control the heating device 613 to work, and heat the liquid 6111 in the transfer tank 615 so that the liquid 6111 reaches the target temperature.
After the liquid in the transfer tank 615 reaches the target temperature, the liquid can be injected into the test tank 611 through the liquid inlet 6117. In this way, the transfer tank 615 can buffer the liquid 6111 in the heating or cooling process of the liquid 6111, and after the temperature of the liquid 6111 in the transfer tank 615 reaches the target temperature, the liquid 6111 is injected into the test tank 6111, so that the accuracy of the temperature of the liquid in the test tank 6111 can be ensured.
Referring to fig. 7, a block diagram of a trimming system 700 according to another embodiment of the present application is shown. Fig. 7 is substantially similar to fig. 2, with the main differences: the tuning system 700 may also include a trimming switching circuit 76. Reference is made to fig. 8 and 9 in combination. Fig. 8 is a schematic diagram illustrating connection between the trimming switching circuit 76 and the acquisition circuit 73 according to an embodiment of the present disclosure. Fig. 9 is a schematic diagram illustrating connection between the trimming switching circuit 76 and the target current sensor 7113 according to an embodiment of the present application.
In fig. 8 and 9, the trimming switching circuit 76 is connected between the collecting circuit 73 and the plurality of target current sensors 7113, and is configured to sequentially connect the collecting circuit 73 to each of the target current sensors 7113 in the trimming order of the plurality of target current sensors 7113, so that the collecting circuit 73 collects the second output voltage of the connected target current sensor 7113. Acquisition circuit 73 includes a standard acquisition port PortA and a plurality of target acquisition ports PortB. In fig. 8, the acquisition circuit 73 illustratively includes 4 target acquisition ports PortB.
The standard acquisition port PortA is connected with the standard current sensor 7112 for acquiring a first output voltage. Each target acquisition port PortB is connected to one trimming switching circuit 76, and is used for acquiring the second output voltage of the target current sensor 7113 communicated with the trimming switching circuit 76. The upper computer 72 is configured to determine trimming parameters of the target current sensors 7113 connected to the trimming switching circuits 76 according to the second output voltages and the first output voltages acquired by the different target acquisition ports PortB.
For any target current sensor 7113 that is communicated by the trimming switching circuit 76, the collecting circuit 73 is specifically configured to collect, at different temperatures, a first output voltage of the standard current sensor 7112 and a second output voltage of the target current sensor 7113; the upper computer 72 is specifically configured to determine trimming parameters of the target current sensor 7113 at different temperatures according to the first output voltage and the second output voltage, and write the trimming parameters at the different temperatures into the target current sensor 7113. After trimming parameters at different temperatures are written into the target current sensor 7113, the trimming switching circuit 76 is specifically configured to switch the connected target current sensor 7113 from the target current sensor 7113 to the next target current sensor 7113.
Take the trimming switching circuit 1 in fig. 9 as an example. The trimming switching circuit 1 may first communicate with the target current sensor 1-1. After determining trimming parameters of the target current sensor 1-1 in each temperature interval and writing the trimming parameters into the target current sensor 1-1, the trimming switching circuit 1 may disconnect the target current sensor 1-1 and connect the target current sensor 1-2. And so on, the trimming parameters of each target current sensor 7113 are obtained.
The trimming system 700 shown in fig. 7, 8 and 9 can perform batch trimming on a plurality of target current sensors 7113, so as to improve trimming efficiency of the target current sensors 7113.
With continued reference to fig. 1, the trimming principle of the trimming system 200 at one of the temperatures (i.e., the target temperature) is described below.
In some embodiments, the power supply 22 is specifically configured to provide alternating current to the standard current sensor 2112 and the target current sensor 2113 as a current to be measured. The acquisition circuit 23 is specifically configured to acquire the first output voltage of the standard current sensor 2112 and the second output voltage of the target current sensor 2113 at the same sampling frequency. Wherein, the same sampling frequency may refer to that the acquisition circuit 23 acquires a first output voltage and a second output voltage from the same time starting point at the same preset time intervals. For example, starting at 0 th second, a first output voltage and a second output voltage are collected every 0.1 second. In this way, at each sampling point in time, a set of output voltages can be obtained, each set comprising a first output voltage and a second output voltage.
It will be appreciated that the magnitude of the current due to the alternating current is periodically variable over time. Therefore, if the first output voltage and the second output voltage are collected at a plurality of different time points in one alternating current period, the first output voltage and the second output voltage corresponding to different currents can be obtained.
For ease of understanding, please refer to fig. 10, which is a schematic diagram of the ac power level change with time according to an embodiment of the present application. In fig. 10, the Y-axis represents the current level and the X-axis represents time. Taking the dotted line as an example, the current levels at the several time points are different. Therefore, if the first output voltage and the second output voltage are acquired at the several time points, the obtained first output voltage and second output voltage are the first output voltage and second output voltage corresponding to different magnitude currents.
That is, after providing an alternating current to be measured for the standard current sensor 2112 and the target current sensor 2113, the first output voltage and the second output voltage corresponding to the currents with different magnitudes can be obtained by collecting the first output voltage and the second output voltage at different time points. In this way, compared with some schemes that the target current sensor 2113 is trimmed by inputting different direct currents for multiple times, the method can greatly shorten the sampling time of the output voltage by inputting the alternating current, and further shorten the trimming time of the target current sensor 2113.
Further, in some embodiments, the power supply 22 is specifically configured to provide alternating current at a first frequency to the standard current sensor 2112 and the target current sensor 2113. The acquisition circuit 23 is specifically configured to acquire the first output voltage and the second output voltage according to a sampling frequency of the second frequency. Wherein the first frequency is less than the second frequency. Because the first frequency is smaller than the second frequency, the first output voltage and the second output voltage can be acquired for multiple times in one alternating current period, and then the first output voltage and the second output voltage corresponding to multiple currents with different magnitudes can be obtained.
In this embodiment, the ac power source provides a sine wave current having an amplitude of 150 amps and a frequency of 40 hertz. The sampling frequency was set to 100 khz and the sampling time point was set to 7500. It will be appreciated that the sampling frequency, the collection time point, the current magnitude and the frequency provided by the ac power source may be set according to practical situations, which is not limited in this application.
In some embodiments, the upper computer 24 is specifically configured to fit the first output voltage and the second output voltage to obtain a fitting result, and determine a trimming parameter of the target current sensor 2113 at the target temperature based on the fitting result and the characteristic parameter of the standard current sensor 2112.
Specifically, in some embodiments, the fitting results may include a fitting curve. The upper computer 24 may fit the first output voltage and the second output voltage based on a least square method well known to those skilled in the art, to obtain a fitted curve of the first output voltage and the second output voltage. Referring specifically to fig. 11, a schematic diagram of a fitted curve according to an embodiment of the present application is provided. In fig. 11, the horizontal axis represents the first output voltage, and the vertical axis represents the second output voltage. The obtained fitting curve can reflect the transformation relation between the first output voltage and the second output voltage.
The fitted curve can be expressed as expression (1):
y＝bx+a(1)
where y may represent the second output voltage acquired, x may represent the first output voltage, and a and b represent the intercept and slope, respectively, of the fitted curve.
Wherein the slope b can be calculated by expression (2):
n represents the number of sampling time points, x represents the first output voltage at each sampling time point, and y represents the second output voltage at each sampling time point.
Intercept a can be calculated by expression (3):
a＝y-bx (3)
in some embodiments, the characteristic parameter of the standard current sensor 2112 may characterize the characteristic index of the standard current sensor 2112, and may specifically include a first zero output voltage and a first gain. Wherein the first zero output voltage characterizes the first output voltage of the standard current sensor 2112 when the input current of the standard current sensor 2112 is 0. The first gain characterizes a ratio of a first output voltage of the standard current sensor 2112 to the input current when the input current of the standard current sensor 2112 is not 0. In this embodiment, the first zero output voltage is set to 0 volts and the first gain is set to 0.005 volts per amp.
The trimming parameters of the target current sensor 2113 may include a zero output trimming parameter and a gain trimming parameter. Wherein the zero output trimming parameter is used to trim the second zero output voltage of the target current sensor 2113 during current detection. The second zero output voltage characterizes a second output voltage of the target current sensor 2113 when the input current of the target current sensor 2113 is 0. The gain trimming parameter is used to trim the second gain of the target current sensor 2113. The second gain of the target current sensor 2113 represents the ratio of the second output voltage of the target current sensor 2113 to the input current when the input current of the target current sensor is not 0.
It will be appreciated that the target current sensor 2113 outputs the voltage V at the second zero point during current detection o Can be obtained by detection. Specifically, after the input current of the target current sensor 2113 is set to 0 a, the second zero output voltage of the target current sensor 2113 is detected by the acquisition circuit 23. But take account ofIn some embodiments of the present application, the host computer 24 may determine the second zero output voltage of the target current sensor 2113 during the current detection based on the fitting result and the first zero output voltage of the standard current sensor 2112, considering that the process of detecting the second zero output voltage may also be time consuming, and may increase the trimming time of the target current sensor 2113. In this way, the second zero output voltage is obtained through calculation, so that the detection time of the second zero output voltage can be saved, and the trimming time of the target current sensor 2113 can be further shortened.
Specifically, the upper computer 24 may determine the second zero output voltage of the target current sensor 2113 during the current detection based on expression (4).
V o ＝b*off+a(4)
Wherein V is o Represents the second zero output voltage of the target current sensor 2113 during current detection, and off represents the first zero output voltage of the standard current sensor 2112.
After obtaining the second zero output voltage, the upper computer 24 may determine the zero output trimming parameter of the target current sensor 2113 according to the difference between the target zero output voltage required by the target current sensor 2113 and the second zero output voltage. The target zero output voltage is the voltage which is expected to be reached by the modified second zero output voltage. In this embodiment, the target zero output voltage is set to 2.5 volts.
Specifically, the zero output trimming parameter of the target current sensor may be determined based on expression (5).
Where ZD represents the zero output trimming parameter of the target current sensor 2113, LSBzd represents the minimum resolution voltage of ZD, V off A target zero output voltage, V, representing the target current sensor 2113 off -V o Represents the difference between the target zero output voltage and the second zero output voltage, ZD ′ Representing a target currentThe sensor 2113 outputs the trimming parameter at zero point before trimming. Here, ZD ′ May be the initial zero output trimming parameter of the target current sensor 2113. This initial zero output trimming parameter may be randomly set, with the problem of inaccuracy, and therefore, the parameter of the target current sensor 2113 needs to be redetermined.
In accordance with principles similar to determining the zero output trimming parameter, in some embodiments, the upper computer 24 may determine a second gain of the target current sensor 2113 during current detection based on the fitting result and the first gain. Further, the gain trimming parameter of the target current sensor 2113 may be determined according to the difference between the target gain required by the target current sensor 2113 and the second gain. Wherein the target gain is a gain that the trimmed second gain is expected to achieve. In this embodiment, the target gain is set to 0.8 volts per 150 amps.
Specifically, the upper computer 24 may determine the second gain of the target current sensor 2113 during the current detection based on expression (6).
V fs ＝b*fs(6)
Wherein V is fs Representing the second gain of the target current sensor 2113 during current sensing, and fs represents the first gain of the standard current sensor 2112.
Further, the gain trimming parameter of the target current sensor 2113 may be determined based on expression (7).
Where GD represents the gain trim parameter, V, of the target current sensor 2113 full Representing the target gain of the target current sensor 2113,
indicates the difference between the target gain and the second gain, GD ′ Representing the gain trim parameter of the target current sensor 2113 prior to trimming.
In this manner, the trim parameter of the target current sensor 2113 at the target temperature may be determined. The determined trimming parameter may be written to the target current sensor 2113 to trim the second output voltage of the target current sensor 2113 and the second gain at the target temperature.
In summary, the trimming system has the beneficial effects of improving trimming precision and shortening trimming duration.
Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope of the invention as defined by the appended claims.
Claims (10)
1. A trimming system for a current sensor, the system comprising:
an oven comprising a test tank for containing a liquid having a target temperature, and a standard current sensor and a target current sensor to be trimmed immersed in the liquid;
the power supply is used for providing current to be measured for the standard current sensor and the target current sensor;
the acquisition circuit is used for acquiring a first output voltage of the standard current sensor and a second output voltage of the target current sensor when the current to be detected passes through the standard current sensor and the target current sensor;
and the upper computer is used for determining the trimming parameters of the target current sensor at the target temperature according to the first output voltage and the second output voltage acquired by the acquisition circuit.
2. The system of claim 1, wherein the oven further comprises a cooling device and a heating device, wherein:
the refrigerating device is used for cooling the liquid when the temperature of the liquid is higher than the target temperature so that the temperature of the liquid reaches the target temperature;
the heating device is used for heating the liquid when the temperature of the liquid is lower than the target temperature so as to enable the temperature of the liquid to reach the target temperature.
3. The system of claim 2, wherein the refrigeration device comprises a compressor connected to the test tank and the host computer, respectively, for cooling the liquid in the test tank to the target temperature based on control of the host computer.
4. The system of claim 3, wherein the compressor comprises a first compressor and a second compressor connected to the first compressor, the first compressor and the second compressor are respectively connected to the upper computer, the second compressor is connected to the test tank, and the first compressor and the second compressor are used for cooling the liquid in the test tank to the target temperature based on the control of the upper computer.
5. The system of claim 2, wherein the heating device comprises a heat generating component connected to the test tank and the host computer, respectively, for heating the liquid in the test tank to the target temperature based on control of the host computer.
6. The system of claim 2, wherein the oven further comprises a transfer tank, the test tank comprises a liquid inlet and a liquid outlet, the transfer tank is connected with the liquid inlet and the liquid outlet, the liquid in the test tank is injected into the transfer tank through the liquid outlet, the refrigeration device cools the liquid in the transfer tank to the target temperature, or the heating device heats the liquid in the transfer tank to the target temperature, and then the liquid in the transfer tank is injected into the test tank through the liquid inlet.
7. The system according to claim 1, wherein the power supply is specifically configured to provide alternating current to the standard current sensor and the target current sensor as the current to be measured;
the acquisition circuit is specifically used for acquiring the first output voltage of the standard current sensor and the second output voltage of the target current sensor according to the same sampling frequency;
the upper computer is specifically configured to fit the first output voltage and the second output voltage to obtain a fitting result, and determine a trimming parameter of the target current sensor at the target temperature based on the fitting result and the characteristic parameter of the standard current sensor.
8. The system of claim 7, wherein the power supply is specifically configured to provide alternating current at a first frequency to the standard current sensor and the target current sensor;
the acquisition circuit is specifically configured to acquire the first output voltage and the second output voltage according to a sampling frequency of a second frequency;
wherein the first frequency is less than the second frequency.
9. The system of claim 7, wherein the characteristic parameter of the standard current sensor comprises a first zero output voltage and the trimming parameter of the target current sensor comprises a zero output trimming parameter;
the upper computer is specifically configured to determine a second zero output voltage of the target current sensor in a current detection process based on the fitting result and the first zero output voltage, and determine a zero output trimming parameter of the target current sensor according to a difference between the target zero output voltage required by the target current sensor and the second zero output voltage.
10. The system of claim 7, wherein the characteristic parameter of the standard current sensor comprises a first gain and the trimming parameter of the target current sensor comprises a gain trimming parameter;
the upper computer is specifically configured to determine a second gain of the target current sensor in a current detection process based on the fitting result and the first gain, and determine a gain trimming parameter of the target current sensor according to a difference between a target gain required by the target current sensor and the second gain.
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