Wide-range AC / DC digital current sensor

Abstract

The invention discloses a wide-range AC / DC digital current sensor. One end of a short-circuit switch is connected with an output IP1 + of a first current sensor, and the other end of the short-circuit switch is connected with an input IP-; the input IP-is connected with primary core penetrating outputs of the second current sensor, the third current sensor and the fourth current sensor; a secondary current conversion signal of the first current sensor is connected with the input of the first analog front end driver and the input of the second analog front end driver; the outputs of the three analog front-end drivers are connected with a CH1 channel, a CH2 channel and a CH3 channel of the multi-channel AD synchronous conversion module; the multi-channel AD synchronous conversion module is connected with the DSP chip and peripheral equipment thereof through an SPI (Serial Peripheral Interface); the DSP chip and the peripheral of the DSP chip drive the short circuit switch, the first gear shifting switch and the second gear shifting switch through IO ports, the sensor achieves wide-range measurement from 100 mA to 1000 A, digital output is adopted, high accuracy of the sensor is guaranteed during wide-current-range-range measurement, meanwhile, measurement abnormity caused by the gear shifting process is avoided, high-precision detection is achieved, and the defects of existing detection are overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a wide-range AC / DC digital current sensor. BACKGROUND

[0002] With the rapid development of new energy technology, electric vehicles as a typical representative of new energy technology also face new challenges in the development process. In the process of electric vehicle charging infrastructure construction, such as charging piles, super charging piles, etc., the accuracy, reliability and intelligence of the current measurement technology become important measurement standards. Especially in the application of super charging piles, super charging piles use high-frequency power electronic devices such as SiC / GaN, which have complex harmonic components in the measured current, making it impossible to obtain accurate measurement results. At the same time, due to the significant increase in the power of charging piles, especially super charging piles, which can reach hundreds of amperes or even kilo-ampere levels at 350kW, it is necessary to ensure the accuracy of electric energy measurement and battery management, and to support full-range high-precision measurement from trickle charging to super fast charging and from milliamperes to hundreds of amperes.

[0003] In the prior art, for the measurement of wide-range current, the measurement scheme and its defects in dealing with wide-range are as follows:

[0004] (1) Shunt measurement, which measures the voltage drop of current on a known resistor and calculates the current value using Ohm's law. There is no isolation in the measurement process, and an additional isolation amplifier is needed. It can theoretically achieve wide-range measurement, but the output voltage is too small to accurately measure, and the range is generally 1%~120% of the rated value, with large temperature offset, and the accuracy is generally only ±0.1%~0.5%.

[0005] (2) Hall effect sensor measurement, which uses a Hall element to detect the magnetic field generated by the current and outputs a proportional voltage signal. However, it has zero drift and temperature drift, low accuracy, and a range of 5%~120% of the rated value, with an accuracy of only ±1%~3%.

[0006] (3) Magnetic flux gate sensor measurement, which uses the periodic saturation characteristics of high-permeability cores to detect small magnetic fields. It has very high precision, up to ±0.01%~0.1%, but the single range is 1~120% of the rated value, and the measurement has limitations.

[0007] (4) Optical fiber current sensor measurement, which is based on the Faraday magneto-optical effect. The current magnetic field changes the polarization state of the light in the optical fiber. The cost is extremely high, the system is complex, and a laser source and an optical-electric conversion are needed. The accuracy is ±0.1%~0.5%, and the range is 5%~120% of the rated value. SUMMARY

[0008] To overcome the above problems, the purpose of this invention is to provide a wide-range AC / DC digital current sensor. This sensor is a digital current sensor with automatic compensation during range switching, which can realize wide-range measurement from 100mA to 1000A. It adopts digital output, ensuring high accuracy when measuring in a wide current range, and will not cause measurement abnormalities due to range switching. It can realize high-precision detection of lithium-ion battery charging and discharging, new energy charging pile detection, photovoltaic power station, wind farm and other distributed energy, and overcome the defects of existing detection.

[0009] The technical solution adopted in this invention is:

[0010] A wide-range AC / DC digital current sensor includes a first current sensor, a second current sensor, a third current sensor, a fourth current sensor, a first analog front-end driver, a second analog front-end driver, a third analog front-end driver, a multi-channel AD synchronous conversion module, a DSP chip and its peripherals, a first diode, a second diode, a short-circuit switch, a first shift switch, and a second shift switch.

[0011] One end of the short-circuit switch is connected to the output IP1+ of the first current sensor, and the other end is connected to the input IP-.

[0012] The input IP- is connected to the primary through-core output of the second current sensor, the third current sensor, and the fourth current sensor;

[0013] The secondary current conversion signal of the first current sensor is connected to the input of the first analog front-end driver and the second analog front-end driver;

[0014] The selection terminal of the first shift switch is connected to the primary side of the second current sensor, the third current sensor, and the fourth current sensor;

[0015] The selection terminal of the second shift switch is connected to the secondary side of the second current sensor, the third current sensor, and the fourth current sensor;

[0016] The common terminal of the second shift switch is connected to the input of the third analog front-end driver;

[0017] The common terminal of the first shift switch is connected to the output IP1+ of the first current sensor;

[0018] The output of the first analog front-end driver is connected to the CH1 channel of the multi-channel AD synchronous conversion module, the output of the second analog front-end driver is connected to the CH2 channel of the multi-channel AD synchronous conversion module, and the output of the third analog front-end driver is connected to the CH3 channel of the multi-channel AD synchronous conversion module.

[0019] The multi-channel AD synchronous conversion module is connected to the DSP chip and its peripherals via an SPI interface.

[0020] The DSP chip and its peripherals drive the short-circuit switch, the first shift switch, and the second shift switch through the I / O port.

[0021] As a further description of the present invention, the primary rated current of the first current sensor is 1000A, the primary rated current of the second current sensor is 100A, the primary rated current of the third current sensor is 10A, and the primary rated current of the fourth current sensor is 1A. When the primary current of the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor is at its rated value, the voltage value after the secondary current conversion is 1V.

[0022] As a further description of the present invention, the input range of the multi-channel AD synchronous conversion module is: .

[0023] As a further description of the present invention, the input ranges of the first analog front-end driver, the second analog front-end driver, and the third analog front-end driver are: .

[0024] As a further description of the present invention, both the first diode and the second diode are 1000A and are connected in parallel on IP1+ and IP-.

[0025] As a further description of the present invention, the primary input of the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor adopts a through-hole structure, and each is composed of a fluxgate current transformer and a precision resistor.

[0026] As a further description of the present invention, the first current sensor has an accuracy of 0.01%, a linearity of 50 ppm, a transformation ratio of 2400, and a precision resistor. .

[0027] As a further description of the present invention, the second current sensor, the third current sensor, and the fourth current sensor have an accuracy of 0.01%, a linearity of 10 ppm, a transformation ratio of 240, and a precision resistor. The primary side of the second current sensor has 1 turn through the core, the primary side of the third current sensor has 10 turns through the core, and the primary side of the fourth current sensor has 100 turns through the core.

[0028] As a further description of the present invention, the first analog front-end driver, the second analog front-end driver and the third analog front-end driver are composed of high-performance amplifiers with adjustable gain, such as AD620. The first analog front-end driver is driven with a 100x amplification, and the second analog front-end driver and the third analog front-end driver are driven with a 1:1 amplification.

[0029] As a further description of the present invention, a network interface is also included. The DSP chip and its peripherals acquire discrete sampled values ​​of the current through a multi-channel AD synchronous conversion module, convert them into IEC 61850-9-2 protocol and send them out through the network interface (U3) at a sampling rate of 12.8kHz.

[0030] The beneficial effects of this invention are:

[0031] This invention discloses a wide-range AC / DC digital current sensor. The digital current sensor converts a small analog voltage signal (0-1V) into a multi-channel analog voltage signal at a 10:1 ratio using four current sensors. After being driven by three analog front-ends, the signal is sent to a multi-channel AD synchronous conversion module to be converted into a current sampling value. The DSP chip and its peripherals read the current sampling value from the multi-channel AD synchronous conversion module via an SPI interface. This digital current sensor achieves a wide measurement range from 100mA to 1000A through automatic compensation technology for range switching using dual AD simultaneous sampling. It employs digital output to ensure high accuracy during wide current range measurements, while preventing data loss or anomalies during range switching. This enables high-precision detection of lithium-ion battery charging and discharging, new energy charging piles, photovoltaic power stations, wind farms, and other distributed energy sources, overcoming the shortcomings of existing detection methods. Attached Figure Description

[0032] Figure 1 This is a circuit diagram of a wide-range AC / DC digital current sensor proposed in this invention;

[0033] Figure 2 This is a schematic diagram of the structure of the first current sensor, the second current sensor, the third current sensor, and the fourth current sensor of a wide-range AC / DC digital current sensor proposed in this invention.

[0034] Figure 3 This is a schematic diagram of the second and third analog front-end drive structures of a wide-range AC / DC digital current sensor proposed in this invention.

[0035] Figure 4 This is a schematic diagram of the first analog front-end drive structure of a wide-range AC / DC digital current sensor proposed in this invention;

[0036] Figure 5 This is a flowchart illustrating the working steps of a sixth embodiment of a wide-range AC / DC digital current sensor proposed in this invention.

[0037] Explanation of reference numerals in the attached figures

[0038] T1 - First current sensor,

[0039] T2 - Second current sensor,

[0040] T3 - Third current sensor

[0041] T4 - Fourth Current Sensor

[0042] A1 - First Analog Front-End Driver

[0043] A2 - Second Analog Front-End Driver

[0044] A3 - Third Analog Front-End Driver

[0045] U1 - Multi-channel AD synchronous conversion module

[0046] U2-DSP chip and its peripherals

[0047] D1 - First diode,

[0048] D2 - Second diode,

[0049] S2 - Short-circuit switch,

[0050] S11 - First gear shift switch

[0051] S12 - Second gear shift switch,

[0052] U3 - Network Interface. Detailed Implementation

[0053] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0054] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0055] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0056] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0057] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0058] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] like Figures 1 to 5 As shown, it illustrates a specific embodiment of the present invention:

[0060] Example 1

[0061] A wide-range AC / DC digital current sensor includes a first current sensor T1, a second current sensor T2, a third current sensor T3, a fourth current sensor T4, a first analog front-end driver A1, a second analog front-end driver A2, a third analog front-end driver A3, a multi-channel AD synchronous conversion module U1, a DSP chip and its peripherals U2, a first diode D1, a second diode D2, a short-circuit switch S2, a first shift switch S11, and a second shift switch S12.

[0062] One end of the short-circuit switch S2 is connected to the output IP1+ of the first current sensor T1, and the other end is connected to the input IP-.

[0063] The input IP- is connected to the first through-core output of the second current sensor T2, the third current sensor T3, and the fourth current sensor T4;

[0064] The secondary current conversion signal of the first current sensor T1 is connected to the input of the first analog front-end driver A1 and the second analog front-end driver A2;

[0065] The selection terminal of the first shift switch S11 is connected to the primary side of the second current sensor T2, the third current sensor T3, and the fourth current sensor T4;

[0066] The selection terminal of the second shift switch S12 is connected to the secondary side of the second current sensor T2, the third current sensor T3, and the fourth current sensor T4.

[0067] The common terminal of the second shift switch S12 is connected to the input of the third analog front-end driver A3;

[0068] The common terminal of the first shift switch S11 is connected to the output IP1+ of the first current sensor T1;

[0069] The output of the first analog front-end driver A1 is connected to the CH1 channel of the multi-channel AD synchronous conversion module U1, the output of the second analog front-end driver A2 is connected to the CH2 channel of the multi-channel AD synchronous conversion module U1, and the output of the third analog front-end driver A3 is connected to the CH3 channel of the multi-channel AD synchronous conversion module U1.

[0070] The multi-channel AD synchronous conversion module U1 is connected to the DSP chip and its peripheral U2 via the SPI interface;

[0071] The DSP chip and its peripheral U2 drive the short-circuit switch S2, the first shift switch S11, and the second shift switch S12 through the IO port.

[0072] In this embodiment, as Figure 1 As shown, this digital current sensor converts the input into a small analog voltage signal of 0~1V through a first current sensor T1, a second current sensor T2, a third current sensor T3, and a fourth current sensor T4 at a ratio of 10:1. After being driven by three analog front-ends, the signal is sent to a multi-channel AD synchronous conversion module U1 to be converted into a current sampling value. The DSP chip and its peripheral U2 read the current sampling value of the multi-channel AD synchronous conversion module U1 through the SPI interface. This digital current sensor achieves a wide range measurement from 100mA to 1000A through automatic compensation technology for range switching with simultaneous dual AD sampling. It adopts digital output to ensure high accuracy when measuring in a wide current range, and at the same time, it will not cause loss or abnormality of current sampling data due to the range switching process. It realizes high-precision detection of lithium-ion battery charging and discharging, new energy charging pile detection, photovoltaic power station, wind farm and other distributed energy, overcoming the defects of existing detection.

[0073] Example 2

[0074] Specifically, the primary rated current of the first current sensor T1 is 1000A, the primary rated current of the second current sensor T2 is 100A, the primary rated current of the third current sensor T3 is 10A, and the primary rated current of the fourth current sensor T4 is 1A. When the primary current of the first current sensor T1, the second current sensor T2, the third current sensor T3, and the fourth current sensor T4 is at its rated value, the voltage value after secondary current conversion is 1V.

[0075] Specifically, the primary inputs of the first current sensor T1, the second current sensor T2, the third current sensor T3, and the fourth current sensor T4 adopt a through-hole structure, and are all composed of fluxgate current transformers and precision resistors.

[0076] Specifically, the first current sensor T1 has an accuracy of 0.01%, a linearity of 50 ppm, a transformation ratio of 2400, and a precision resistor. .

[0077] Specifically, the second current sensor T2, the third current sensor T3, and the fourth current sensor T4 have an accuracy of 0.01%, a linearity of 10ppm, a transformation ratio of 240, and a precision resistor. The primary side of the second current sensor T2 has 1 turn through the core, the primary side of the third current sensor T3 has 10 turns through the core, and the primary side of the fourth current sensor T4 has 100 turns through the core.

[0078] In this embodiment, as Figure 2 The diagram shown is a structural schematic of the first current sensor T1, the second current sensor T2, the third current sensor T3, and the fourth current sensor T4. Precision resistors with a tolerance of 0.01% are available.

[0079] Example 3

[0080] Specifically, the input range of the multi-channel AD synchronous conversion module U1 is -2.5VDC to +2.5VDC.

[0081] In this embodiment, the sampling accuracy of the multi-channel AD synchronous conversion module U1 is not less than 10ppm. It can be selected as a 24-bit 8-channel synchronous sigma-delta AD converter ADS1278. The typical integral error of this chip is ±0.0003%, the maximum sampling rate is 128KSPS, the accuracy of the reference voltage is not less than 200ppm, the temperature drift is not higher than 3ppm, the reference voltage value is 2.5V, and it can be selected as MAX6325ESA with 0.02% initial accuracy and 1ppm temperature drift.

[0082] Specifically, the input range of the first analog front-end driver A1, the second analog front-end driver A2, and the third analog front-end driver A3 is -2.5VDC to +2.5VDC.

[0083] Specifically, the first analog front-end driver A1, the second analog front-end driver A2, and the third analog front-end driver A3 are composed of high-performance amplifiers with adjustable gain, using AD620. The first analog front-end driver A1 is driven with a 100x amplification, while the second analog front-end driver A2 and the third analog front-end driver A3 are driven with a 1:1 amplification.

[0084] In this embodiment, as Figure 3 The diagram shows the structure of the second analog front-end driver A2 and the third analog front-end driver A3. The right side of the driver is suspended, and the magnification factor is 1, achieving a 1:1 amplification drive.

[0085] In this embodiment, as Figure 4 The diagram shown is a schematic of the first analog front-end driver A1. The gain of this amplifier is:

[0086] ,

[0087] when At that time, the amplification gain was 100 times, of which It consists of multiple 0.01% precision resistors connected in series and parallel.

[0088] Example 4

[0089] Specifically, the first diode D1 and the second diode D2 are both 1000A and are connected in parallel to IP1+ and IP-.

[0090] In this embodiment, the first diode D1 and the second diode D2 are configured to prevent damage to the sensor caused by a sudden increase in current during the switching process.

[0091] Specifically, it also includes network interface U3. The DSP chip and its peripheral U2 collect discrete sampled values ​​of the current through the multi-channel AD synchronous conversion module U1, convert them into IEC 61850-9-2 protocol and send them out through network interface U3, with a sampling rate of 12.8kHz.

[0092] In this embodiment, the DSP chip and its peripheral U2 use a clock frequency of not less than 100MHz and corresponding peripherals. The chip can be composed of ADI's BF609 chip and its peripherals. The chip has a large number of built-in peripherals, including one SPI interface, 16 general-purpose I / O ports, an AMC interface (asynchronous memory interface), one network port, 256MB YTE DRAM, and the core algorithm used to complete the present invention.

[0093] Example 5

[0094] Based on the above embodiments, this embodiment describes its working principle.

[0095] In this embodiment, the multi-channel AD synchronous conversion module U1 simultaneously acquires current signals through AD conversion of 3 channels.

[0096] CH1 amplifies the 1000A current sensor by 100 times and continuously samples. Signal acquisition is normal when the signal is less than 10A; otherwise, the signal is a clipped sine wave. CH2 amplifies the 1000A current sensor by 1 time and continuously samples. CH3 only samples when the current is less than or equal to 100A, switching to different ranges based on the current range. There are a total of three ranges, with a 10x range interval, including the 1000A range, resulting in four effective ranges with a 10x interval. It is expandable. The measurement range is doubled. This enables wide-range, accurate measurement of the current sensor under steady-state conditions. During gear switching, by selecting sampling data from different channels of the multi-channel AD synchronous conversion module U1, continuous and highly accurate sampling values ​​can be obtained across different input current ranges and during gear shifting.

[0097] During gear shifting, when the current is between 100 and 1000A, the sampling data of CH2 is taken as the transition current sampling value during the gear shifting process.

[0098] During gear shifting, when the current is between 10A and 100A, the sampled data of CH2 after calibration and amplification by 1 time is taken as the transition current sample value of the gear shifting process.

[0099] During gear shifting, when the current is between 0.1 and 10A, the sampled data of CH1, which has been calibrated and amplified by 100 times, is taken as the transition current sample value.

[0100] In normal steady state, i.e. when the gear is not switched, when the current is ≥100A, the sampling data of CH2 is taken as the current sampling value.

[0101] In normal steady state, i.e. when the gear is not switched, when 10A≤current<100A, the sampling data of CH3 is taken as the current sampling value. When switching to the 100A gear position, the sampling data of CH3 is the optimal data after the gear shift. The effective value of CH3 and the effective value of CH2 are calculated at 20ms time, which are used as the latest calibration coefficient X[2] in the gear shifting process. The default value of X[2] is 1 when powered on.

[0102] , , , ,

[0103] In normal steady state, i.e. when the gear is not switched, when 1A≤current<10A, the sampling data of CH3 is taken for calculation. When the gear is switched to the 10A position, the sampling data of CH3 is the optimal data after the gear shift. The effective value of CH3 and the effective value of CH1 are calculated at the same time every 20ms, which are used as the latest calibration coefficient X[1].

[0104] , , , .

[0105] In normal steady state, i.e. when the gear is not switched, when the current is 0.1A≤1A, the sampling data of CH3 is taken for calculation. When the gear is switched to the 1A position, the sampling data of CH3 is the optimal data after the gear shift. The effective value of CH3 and the effective value of CH1 are calculated at the same time every 20ms, which are used as the latest calibration coefficient X[0] in the gear shifting process.

[0106] , , , ,

[0107] Example 6

[0108] Based on the above embodiments, such as Figure 5 As shown, this embodiment describes the working steps of the above embodiments.

[0109] Step 1: When powered on, the current setting is set to 1000A by default, and the default calibration coefficient is 1. The DSP chip and its peripheral U2 control the gear setting through the shift switches S11 and S12. When the short-circuit switch S2 is closed, the default values ​​of the calibration coefficients X[0], X[1], and X[2] are all 1.

[0110] Step 2: Based on the current values ​​sampled from CH1 and CH2, determine whether a gear shift is required according to Table 1 below.

[0111] Table 1 Shift Logic

[0112]

[0113] Since the CH1 and CH2 of the multi-channel AD synchronous conversion module U1 acquire the secondary output of the 1000A current sensor T1, and the 1000A current sensor T1 does not switch ranges, the range switching is calculated based on the sampled values ​​of CH1 and CH2.

[0114] CH1 is amplified by 100 times, resulting in higher accuracy for currents below 10A.

[0115] The current value during gear shifting is first calculated from the sampling data of CH2 of the multi-channel AD synchronous conversion module U1. When the current value I is less than 10A, the current value is then calculated from the sampling data of CH1 of the multi-channel AD synchronous conversion module U1.

[0116] Step 3: Determine whether the current short-circuit switch S2 and shift switches S11 and S12 are consistent with the current value I. If they are consistent, proceed to step A without shifting. If they are inconsistent, proceed to step B, where shifting is required. Temporary sampling values ​​are needed during the shifting process.

[0117] Step A:

[0118] Based on the current current value I, calculate the calibration coefficients X[2], X[1], and X[0]. These calibration coefficients are used to calibrate the sampling channels CH2 and CH1 during the gear switching process in step B.

[0119] Select the sampling channel and magnification of the multi-channel AD synchronous conversion module U1 according to Table 2 below and output the sampling value. The sampling value is the original AD sampling value of the multi-channel AD synchronous conversion module U1 multiplied by the magnification, where the magnification is the reciprocal of the sensor transformation ratio.

[0120] Table 2. Steady-state current sampling value channel selection and magnification

[0121]

[0122] Step B:

[0123] First, close the short-circuit switch S2, then delay for 50ms. Based on the current value, switch gears according to Table 1, then delay for 50ms. After switching, open the short-circuit switch S2 to ensure that the current does not open during the switching process. The first diode D1 and the second diode D2 are to prevent the short-circuit switch S2 and the gear shift switch S11 from being in an open-circuit state at the same time. The sampling value is the transition AD original sampling value of the multi-channel AD synchronous conversion module U1 multiplied by the corresponding magnification and the corresponding calibration coefficient. The magnification is the reciprocal of the amplification factor of the first analog front-end driver A1 and the second analog front-end driver A2.

[0124] Table 3. Transition Current Sampling Value Channel Selection and Multiplier

[0125]

[0126] Step 4: Convert the sampled values ​​to the IEC 61850-9-2 protocol and send them to the network interface to proceed to the next sampling point.

[0127] In summary, this sensor achieves its shifting process by designing a main sampling range CH1, which employs dual-channel synchronous sampling at different magnifications. CH1 serves as the basis for shifting sampling and as the output of the transitional sampling value during the shifting process. During periods without shifting, the accuracy data of CH3 is used to calibrate CH1 and CH2, thereby ensuring that the accuracy remains constant or changes only slightly during the shifting process. For sensors with currents below 100A, the sensor's primary range is switched while keeping the sampling channels CH1 and CH2 unaffected by the shift, ensuring the continuity of the shifting process. Since high accuracy can be achieved across the entire range of 0.1A to 1000A with a single sampling shift, and digital signal output ensures high precision of the secondary output over an ultra-wide range.

[0128] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0129] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A wide-range AC / DC digital current sensor, characterized in that, Including short-circuit switch (S2). One end of the short-circuit switch (S2) is connected to the output IP1+ of the first current sensor (T1), and the other end is connected to the input IP-. The input IP- is connected to the first through-core output of the second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4); The secondary current conversion signal of the first current sensor (T1) is connected to the input of the first analog front-end driver (A1) and the second analog front-end driver (A2); It also includes a first shift switch (S11) and a second shift switch (S12). The selection terminal of the first shift switch (S11) is connected to the primary side of the second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4); The selection terminal of the second shift switch (S12) is connected to the secondary side of the second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4); The common terminal of the second shift switch (S12) is connected to the input of the third analog front-end driver (A3); The common terminal of the first shift switch (S11) is connected to the output IP1+ of the first current sensor (T1); The output of the first analog front-end driver (A1) is connected to the CH1 channel of the multi-channel AD synchronous conversion module (U1), the output of the second analog front-end driver (A2) is connected to the CH2 channel of the multi-channel AD synchronous conversion module (U1), and the output of the third analog front-end driver (A3) is connected to the CH3 channel of the multi-channel AD synchronous conversion module (U1). The multi-channel AD synchronous conversion module (U1) is connected to the DSP chip and its peripherals (U2) via an SPI interface; The DSP chip and its peripherals (U2) drive the short-circuit switch (S2), the first shift switch (S11), and the second shift switch (S12) through the IO port.

2. The wide-range AC / DC digital current sensor according to claim 1, characterized in that, The primary rated current of the first current sensor (T1) is 1000A, the primary rated current of the second current sensor (T2) is 100A, the primary rated current of the third current sensor (T3) is 10A, and the primary rated current of the fourth current sensor (T4) is 1A. When the primary current of the first current sensor (T1), the second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4) are at their rated values, the voltage value after secondary current conversion is 1V.

3. The wide-range AC / DC digital current sensor according to claim 1, characterized in that, The input range of the multi-channel AD synchronous conversion module (U1) is -2.5VDC to +2.5VDC.

4. A wide-range AC / DC digital current sensor according to claim 1, characterized in that, The input range of the first analog front-end driver (A1), the second analog front-end driver (A2), and the third analog front-end driver (A3) is -2.5VDC to +2.5VDC.

5. A wide-range AC / DC digital current sensor according to claim 1, characterized in that, The first diode (D1) and the second diode (D2) are both 1000A and are connected in parallel to IP1+ and IP-.

6. A wide-range AC / DC digital current sensor according to claim 1, characterized in that, The primary inputs of the first current sensor (T1), the second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4) adopt a through-hole structure and are all composed of fluxgate current transformers and precision resistors.

7. A wide-range AC / DC digital current sensor according to claim 6, characterized in that, The first current sensor (T1) has an accuracy of 0.01%, a linearity of 50 ppm, a transformation ratio of 2400, and a precision resistor. .

8. A wide-range AC / DC digital current sensor according to claim 6, characterized in that, The second current sensor (T2), the third current sensor (T3), and the fourth current sensor (T4) have an accuracy of 0.01%, a linearity of 10 ppm, a transformation ratio of 240, and a precision resistor. The primary side of the second current sensor (T2) is 1 turn through-core, the primary side of the third current sensor (T3) is 10 turns of equal ampere-turns, and the primary side of the fourth current sensor (T4) is 100 turns of equal ampere-turns.

9. A wide-range AC / DC digital current sensor according to claim 1, characterized in that, The first analog front-end driver (A1), the second analog front-end driver (A2), and the third analog front-end driver (A3) are composed of high-performance amplifiers with adjustable gain, using AD620. The first analog front-end driver (A1) is driven with a 100x amplification, while the second analog front-end driver (A2) and the third analog front-end driver (A3) are driven with a 1:1 amplification.

10. A wide-range AC / DC digital current sensor according to claim 1, characterized in that, It also includes a network interface (U3), through which the DSP chip and its peripherals (U2) collect discrete sampled values ​​of the current via a multi-channel AD synchronous conversion module (U1), convert them into IEC 61850-9-2 protocol and send them out via the network interface (U3) at a sampling rate of 12.8kHz.

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