Wide-temperature dynamic cross direct-current magnetic saturation type high-precision current transformer

Abstract

The present application relates to the technical field of current transformer, in particular to a wide temperature dynamic DC magnetic saturation type high-precision current transformer, which adopts nanocrystalline and silicon steel sheet composite main iron core, in which a magnetic flux collection unit is embedded at the air gap to directly collect main magnetic flux, an integrated control unit extracts DC bias component, PI closed loop adjustment is performed on the driving compensation winding to output reverse excitation magnetic flux, dynamic offsetting unidirectional magnetization is performed to suppress core saturation from the root. Meanwhile, a temperature sensor collects core temperature in real time, a temperature-permeability coupling model is used to update magnetic resistance, and amplitude and phase correction is performed on secondary output to realize 0.2S level measurement accuracy in the whole temperature range of -40 DEG C to 85 DEG C. The components are integrally vacuum cast packaged by epoxy resin, and the structure is compact and excellent in insulation. The present application improves the anti-saturation ability and wide temperature precision of the current transformer from the dual dimensions of hardware magnetic circuit and electrical compensation, and is suitable for high-precision measurement and relay protection of medium voltage distribution network, new energy grid connection and DC distribution network.

Description

Technical Field

[0001] This invention belongs to the technical field of instrument transformers for power transmission and distribution system engineering applications, specifically involving a wide-temperature dynamic AC / DC magnetic saturation elimination high-precision current transformer. Background Technology

[0002] Current transformers are core equipment in power systems for relay protection, power metering, and power monitoring. Their measurement accuracy and operational stability directly determine the level of safe and reliable operation of the power system.

[0003] Currently, traditional current transformers in the power industry mostly employ passive optimization structures to combat saturation: relying on static magnetic circuit methods such as increasing the core cross-sectional area, adding a fixed air gap, and using composite cores made of dissimilar materials to delay saturation. These methods can only weaken the saturation trend and cannot dynamically offset random changes in DC bias flux. Under DC component fluctuations and fault impacts, the core will still unidirectionally magnetize and saturate, and the distortion of the secondary current waveform cannot be eliminated.

[0004] Traditional current transformers have significant drawbacks in terms of wide-temperature error: existing products rely solely on hardware materials to improve temperature drift, lacking closed-loop digital correction logic. In the outdoor temperature range of -40℃ to 85℃, nonlinear drift in the core permeability causes excessive ratio and angle errors, with conventional products exhibiting temperature drift errors exceeding 0.6%, making it difficult to consistently meet the State Grid's 0.2S-level metering accuracy requirements.

[0005] Traditional current transformers also have shortcomings in terms of structural integration: the detection winding and excitation winding of existing active compensation schemes are scattered, the peripheral circuits are fragmented, they cannot be integrated into a cast-in-place package, they are large in size, have high difficulty in partial discharge control, and are difficult to adapt to the requirements of medium voltage ring main units for compact product structure and excellent insulation characteristics. Summary of the Invention

[0006] In view of the above problems, the purpose of this application is to provide a wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer, which solves the problems of easy magnetic saturation, poor accuracy under high and low temperature conditions, limited range, and insufficient stability and reliability of traditional current transformers, so as to realize wide-temperature range, wide range, and high-precision current measurement and signal acquisition, and meet the high-precision metering and protection requirements of the State Grid and new energy power systems under complex operating conditions.

[0007] To achieve some or all of the above objectives or other objectives, this application provides the following technical solution: a wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer, comprising a composite main core, a primary winding, a secondary measuring winding, a flux compensation winding, an auxiliary power supply capacitor unit, a flux acquisition and sensing unit, an integrated control unit, and a temperature sensor; the composite main core comprises a nanocrystalline core and a silicon steel sheet core, and has an air gap; the flux acquisition and sensing unit is embedded in the air gap of the composite main core; the temperature sensor is attached to the side wall of the composite main core; the integrated control unit is electrically connected to the flux acquisition and sensing unit, the temperature sensor, the secondary measuring winding, and the flux compensation winding respectively; the auxiliary power supply capacitor unit supplies power to the integrated control unit.

[0008] Furthermore, the integrated control unit includes a main control unit, a temperature sampling and conditioning circuit, a signal conditioning circuit, a current sampling circuit, and a core unit of the main control compensation circuit; the core unit of the main control compensation circuit includes a DC component extraction module, a reverse compensation excitation current calculation unit, and a temperature-permeability coupling error correction algorithm unit; the temperature sensor is connected to the main control unit through the temperature sampling and conditioning circuit; the magnetic flux acquisition sensing unit is connected to the main control unit through the signal conditioning circuit; the secondary measurement winding is connected to the core unit of the main control compensation circuit through the current sampling circuit; the magnetic flux compensation winding is controlled by the core unit of the main control compensation circuit.

[0009] Furthermore, the magnetic flux acquisition sensing unit outputs a voltage signal. The voltage signal is proportional to the rate of change of magnetic flux within the composite main core: In the formula: This refers to the number of coil turns in the magnetic flux acquisition sensing unit. The effective cross-sectional area of ​​the composite main core, The real-time total magnetic flux of the iron core is obtained by the main control unit digitally integrating the voltage signal. The DC component extraction module samples the secondary measurement winding current, uses a digital phase-locked loop to lock the power frequency synchronous phase, and combines a moving average and a first-order digital low-pass filter to extract the DC bias component from the power frequency, harmonics, and DC superposition signals.

[0010] Furthermore, the main control unit, based on the extracted DC bias current component... Calculate the DC bias magnetomotive force: In the formula, The number of turns in the primary winding; according to Ohm's law for magnetic circuits, the bias flux and magnetomotive force satisfy: In the formula, The dynamic total magnetic reluctance of the iron core is strongly correlated with magnetic flux density B, operating temperature T, BH characteristics, and air gap size; piecewise linearization is applied to the magnetic reluctance. In the formula: The average length of the magnetic circuit of the iron core. The permeability of free space, This represents the equivalent relative permeability of the iron core at the current magnetic flux density and temperature. For air gap reluctance; to cancel unidirectional bias flux, the flux compensation winding outputs a reverse-biased magnetomotive force: The ideal excitation current of the flux compensation winding is: In the formula, The number of turns in the flux compensation winding; the main control unit uses a PI closed-loop regulator, with zero flux as the control target, and adjusts the drive current of the compensation winding according to the flux error: In the formula, These are the proportional and integral adjustment coefficients, respectively; by suppressing model mismatch caused by hysteresis and eddy currents through closed-loop control, the unidirectional magnetization saturation caused by DC bias is dynamically eliminated.

[0011] Furthermore, the temperature sensor acquires the temperature T of the composite main core, and the temperature-permeability coupling error correction algorithm unit calls the factory-calibrated permeability-temperature fitting curve to perform polynomial temperature correction on the equivalent relative permeability of the core: In the formula, For reference calibration temperature, The initial relative permeability at the reference temperature. The calibration coefficient for high and low temperature tests is the first-order temperature coefficient of nanocrystalline materials. Value ; will be updated in real time Substituting back into the total magnetic reluctance formula: Substitute the values ​​into the total reluctance calculation, recalculate the ideal excitation current of the flux compensation winding, and complete the temperature coupling correction at the magnetic circuit level.

[0012] Furthermore, the main control unit acquires the current measured temperature T of the iron core, retrieves the factory-calibrated ratio difference-temperature curve and angle difference-temperature curve, and performs digital amplitude and phase correction on the secondary current output by the secondary measurement winding: In the formula, These are the amplitude and phase of the original sampled current of the secondary winding, respectively. These represent the amplitude and phase of the output current after temperature drift compensation. The temperature correlation ratio difference This is due to temperature-dependent angle difference; through the above correction, the current transformer meets the 0.2S level metering accuracy requirement across the entire temperature range of -40℃ to 85℃.

[0013] The composite main iron core, primary winding, secondary measurement winding, magnetic flux compensation winding, magnetic flux acquisition sensing unit, integrated control unit and temperature sensor adopt an epoxy resin integrated vacuum casting encapsulation structure.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) Suppressing magnetic saturation from both hardware magnetic circuit structure and electrical intelligent compensation. The main magnetic flux of the magnetic circuit is directly collected by the magnetic flux acquisition sensing unit, which improves the sampling accuracy of the DC bias signal; the magnetic flux compensation winding outputs reverse excitation magnetic flux under closed-loop control, which suppresses the unidirectional magnetization saturation of the iron core from the source and greatly widens the linear measurement range.

[0015] (2) Maintain high-precision metrological performance over a wide temperature range. The core permeability is dynamically updated by a temperature-permeability coupling error correction algorithm. Combined with digital correction of the amplitude and phase of the secondary measurement output signal, the metrological error caused by temperature drift of the core permeability is effectively suppressed, and the metrological accuracy requirement of 0.2S is metrologically achieved over the entire temperature range of -40℃ to 85℃.

[0016] (3) High structural integration and excellent insulation performance. The sensing unit, winding and main control circuit are highly integrated and adopt the epoxy resin integrated vacuum casting process. The product has a compact structure and is suitable for the miniaturization requirements of medium voltage ring main units and power transmission and distribution equipment.

[0017] (4) High adaptability. It can be applied to the high-precision power metering and reliable relay protection standards for power transmission and distribution substations, DC distribution networks, photovoltaic / wind power grid-connected stations and important industrial power distribution scenarios. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a side view of the overall structure of the present invention; Figure 3 This is a diagram of the integrated control unit (circuit control connection) of the present invention; Figure 4 The characteristics of this invention are shown in the comparison chart of the ratio difference and temperature characteristics before and after compensation. Figure 5 The characteristics of this invention are shown in the comparison chart of angle difference and temperature characteristics before and after compensation. Figure 6 The following is a comparison chart of the ratio difference before and after compensation under DC bias conditions, which is a characteristic of the present invention. Explanation of reference numerals in the attached figures: 1. Composite main core; 2. Primary winding; 3. Secondary measuring winding; 4. Flux compensation winding; 5. Auxiliary power supply capacitor unit; 6. Flux acquisition sensing unit; 7. Integrated control unit; 8. Temperature sensor. 702. Main control unit; 704. Temperature sampling and conditioning circuit; 706. Signal conditioning circuit; 708. Current sampling circuit; 709. DC component extraction module; 710. Reverse compensation excitation current calculation unit; 711. Temperature-permeability coupling error correction algorithm unit; 713. Back-end equipment - relay protection device power meter. Detailed Implementation

[0019] To make the structure and function of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0020] See appendix Figure 1-6 A wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer includes a composite main core 1, a primary winding 2, a secondary measuring winding 3, a magnetic flux compensation winding 4, an auxiliary power supply capacitor unit 5, a magnetic flux acquisition and sensing unit 6, an integrated control unit 7, and a temperature sensor 8. The composite main core 1 comprises a nanocrystalline core and a silicon steel sheet core, and has an air gap. The magnetic flux acquisition and sensing unit 6 is embedded in the air gap of the composite main core 1. The temperature sensor 8 is attached to the side wall of the composite main core 1. The integrated control unit 7 is electrically connected to the magnetic flux acquisition and sensing unit 6, the temperature sensor 8, the secondary measuring winding 3, and the magnetic flux compensation winding 4. The auxiliary power supply capacitor unit 5 supplies power to the integrated control unit 7.

[0021] The integrated control unit 7 includes a main control unit 702, a temperature sampling and conditioning circuit 704, a signal conditioning circuit 706, a current sampling circuit 708, and a main control compensation circuit core unit. The main control compensation circuit core unit includes a DC component extraction module 709, a reverse compensation excitation current calculation unit 710, and a temperature-permeability coupling error correction algorithm unit 711. The main control compensation circuit core unit is matched with the downstream equipment—the relay protection device energy meter 713—for control output. The temperature sensor 8 is connected to the main control unit 702 through the temperature sampling and conditioning circuit 704. The magnetic flux acquisition sensing unit 6 is connected to the main control unit 702 through the signal conditioning circuit 706. The secondary measurement winding 3 is connected to the main control compensation circuit core unit through the current sampling circuit 708. The magnetic flux compensation winding 4 is controlled by the main control compensation circuit core unit.

[0022] The magnetic flux acquisition sensing unit 6 outputs a voltage signal. The voltage signal is proportional to the rate of change of magnetic flux within the composite main core 1: In the formula: The number of coil turns in the flux acquisition sensing unit 6. The effective cross-sectional area of ​​the composite main core, The real-time total magnetic flux of the iron core is obtained by the main control unit 702 digitally integrating the voltage signal. The DC component extraction module 709 samples the current of the secondary measurement winding 3, uses a digital phase-locked loop to lock the power frequency synchronous phase, and combines moving average and first-order digital low-pass filtering to extract the DC bias component from the power frequency, harmonics, and DC superposition signals. (Secondary measurement winding 3 current) It includes the fundamental frequency, harmonic components, and DC bias components, and uses a digital phase-locked loop (DPLL) to lock the power frequency synchronization phase. The DC bias component of the DC component extraction module 709 is separated and extracted. For signals consisting of power frequency, harmonics, and DC superposition, a DPLL combined with a moving average is used to quickly strip away the DC offset; to distinguish between slowly varying DC bias and transient DC impacts caused by faults, a first-order digital low-pass filter is connected in series. time constant Value Filter coefficients This is the ADC sampling period.

[0023] The main control unit 702 extracts the DC bias current component. Calculate the DC bias magnetomotive force: In the formula, The primary winding has 2 turns; according to Ohm's law for magnetic circuits, the bias flux and magnetomotive force satisfy: In the formula, The dynamic total magnetic reluctance of the iron core is strongly correlated with magnetic flux density B, operating temperature T, BH characteristics, and air gap size; piecewise linearization is applied to the magnetic reluctance. In the formula: The average length of the magnetic circuit of the iron core. The permeability of free space, This represents the equivalent relative permeability of the iron core at the current magnetic flux density and temperature. For air gap reluctance; to cancel unidirectional bias flux, flux compensation winding 4 outputs a reverse-biased magnetomotive force: The ideal excitation current for flux compensation winding 4 is: In the formula, The flux compensation winding has 4 turns; the main control unit 702 uses a PI closed-loop regulator, with zero flux as the control target, and adjusts the drive current of the compensation winding according to the flux error. In the formula, These are the proportional and integral control coefficients, respectively. The model mismatch caused by hysteresis and eddy currents is suppressed through closed-loop control, dynamically eliminating unidirectional magnetization saturation caused by DC bias. The ideal model does not consider the dynamic effects of core hysteresis and eddy currents; therefore, a PI closed-loop controller is used to achieve zero-flux closed-loop control. The target operating point for flux is determined. Magnetic flux error .

[0024] The temperature sensor 8 collects the body temperature T of the composite main iron core 1, and the temperature-permeability coupling error correction algorithm unit 711 calls the factory-calibrated permeability-temperature fitting curve to perform polynomial temperature correction on the equivalent relative permeability of the iron core: In the formula, For reference calibration temperature, The initial relative permeability at the reference temperature. The calibration coefficient for high and low temperature tests is the first-order temperature coefficient of nanocrystalline materials. Value ; will be updated in real time Substituting back into the total magnetic reluctance formula: Substitute the values ​​into the total reluctance calculation, recalculate the ideal excitation current of flux compensation winding 4, and complete the temperature coupling correction at the magnetic circuit level.

[0025] The system operation and control of the secondary measurement winding 3, the flux compensation winding 4, the auxiliary power supply capacitor unit 5, and the flux acquisition sensor unit 6 effectively control and correct the accuracy of the temperature drift error output by the secondary measurement winding 3. It should be noted that this correction applies to the output signal of the secondary measurement winding 3, not the flux compensation winding, and is used to correct the metering ratio difference and angle difference introduced by material temperature drift.

[0026] The main control unit 702 acquires the current measured temperature T of the iron core, retrieves the factory-calibrated ratio difference-temperature curve and angle difference-temperature curve, and performs digital amplitude and phase correction on the secondary current output by the secondary measurement winding 3. In the formula, These are the amplitude and phase of the original sampled current of the secondary winding, respectively. These represent the amplitude and phase of the output current after temperature drift compensation. The temperature correlation ratio difference This is due to temperature-dependent angle difference; through the above correction, the current transformer meets the 0.2S level metering accuracy requirement across the entire temperature range of -40℃ to 85℃.

[0027] The composite main core 1, primary winding 2, secondary measuring winding 3, flux compensation winding 4, flux acquisition sensing unit 6, integrated control unit 7, and temperature sensor 8 adopt an integrated epoxy resin vacuum casting encapsulation structure. This ensures the typical temperature drift characteristic range of the current transformer is as follows: Nearby difference , Nearby difference After correction, the entire temperature range meets and reaches the 0.2S level of measurement error accuracy standard requirements.

[0028] Based on the above technical features, the present invention has the following beneficial effects and results: such as Figure 4 As shown, before compensation, the ratio error of the current transformer without temperature correction exhibits a significant negative drift with increasing temperature. Within the range of -40℃ to 80℃, the ratio error decreases from +0.3% to -0.3%, exceeding the 0.2S-level ±0.2% error limit at both high and low temperatures. After the temperature-permeability coupling error correction of this invention, the slope of the ratio error-temperature curve is significantly reduced, and the ratio error is constrained within ±0.2% across the entire temperature range of -40℃ to 80℃, effectively suppressing the measurement error caused by the temperature drift of the core permeability.

[0029] like Figure 5 As shown, the black dashed line represents the phase angle error-temperature characteristic curve of a conventional current transformer without temperature correction before compensation; the black solid line represents the phase angle error-temperature characteristic curve after temperature-permeability coupling error correction according to the present invention; the red dotted line represents the allowable phase angle error limit of ±10′ for 0.2S-level metering. It can be seen that the present invention stably controls the phase angle error within the allowable limit across the entire temperature range.

[0030] like Figure 6 As shown, when a DC bias component exists in the primary circuit, traditional static anti-saturation current transformers rely solely on static magnetic circuit methods such as core cross-sectional area and fixed air gap to delay saturation. Under no DC bias (K_dc=0) conditions, the error is still acceptable; however, as the DC bias coefficient K_dc increases, the unidirectional magnetization of the core intensifies, and the ratio difference rapidly deteriorates negatively; when K_dc>0.2, the ratio difference exceeds the 0.2% error limit of the 0.2S level; when K_dc=1.0, the ratio difference reaches -2.2%, and the transformer metering fails. This invention uses an air gap-embedded flux acquisition sensing unit 6 to collect the core's main flux in real time. A digital closed-loop control system calculates the amplitude and polarity of the DC bias, driving the flux compensation winding to output reverse excitation flux to cancel the unidirectional magnetization. Within the full range of DC bias coefficient K_dc from 0 to 1.0, the transformer ratio difference is always controlled within ±0.2%. Even under strong DC bias fault conditions, it still maintains a stable metering accuracy of 0.2S, thus suppressing core saturation and secondary waveform distortion caused by DC bias from the root.

[0031] This invention employs reliable and advanced manufacturing processes to highly integrate the sensing unit, windings, and main control circuit of the current transformer. It adopts a suitable epoxy resin integrated vacuum casting process to ensure that the product has a compact structure and excellent insulation performance, thus guaranteeing the safety, stability, and reliability of the current transformer in power grid operation.

[0032] In the description of this invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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 limiting this invention.

[0033] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall still fall within the scope of this application.

Claims

1. A wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer, characterized in that, It includes a composite main iron core (1), a primary winding (2), a secondary measurement winding (3), a magnetic flux compensation winding (4), an auxiliary power supply capacitor unit (5), a magnetic flux acquisition sensing unit (6), an integrated control unit (7), and a temperature sensor (8). The composite main core (1) includes a nanocrystalline core and a silicon steel sheet core, and is provided with an air gap; The magnetic flux acquisition sensing unit (6) is embedded in the air gap of the composite main iron core (1); The temperature sensor (8) is attached to the side wall of the composite main iron core (1); The integrated control unit (7) is electrically connected to the magnetic flux acquisition sensing unit (6), the temperature sensor (8), the secondary measurement winding (3), and the magnetic flux compensation winding (4), respectively. The auxiliary power supply capacitor unit (5) supplies power to the integrated control unit (7).

2. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 1, characterized in that, The integrated control unit (7) includes a main control unit (702), a temperature sampling and conditioning circuit (704), a signal conditioning circuit (706), a current sampling circuit (708), and a main control compensation circuit core unit; The core unit of the main control compensation circuit includes a DC component extraction module (709), a reverse compensation excitation current calculation unit (710), and a temperature-permeability coupling error correction algorithm unit (711). The temperature sensor (8) is connected to the main control unit (702) through the temperature sampling and conditioning circuit (704); The magnetic flux acquisition sensing unit (6) is connected to the main control unit (702) through the signal conditioning circuit (706); The secondary measurement winding (3) is connected to the core unit of the main control compensation circuit through the current sampling circuit (708); The flux compensation winding (4) is controlled by the core unit of the main control compensation circuit.

3. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 2, characterized in that, The magnetic flux acquisition sensing unit (6) outputs a voltage signal. The voltage signal is proportional to the rate of change of magnetic flux within the composite main core (1): In the formula: The number of coil turns of the magnetic flux acquisition sensing unit (6) The effective cross-sectional area of ​​the composite main core, This represents the real-time total magnetic flux of the iron core; The main control unit (702) performs digital integration on the voltage signal to obtain the real-time total magnetic flux of the iron core: ; The DC component extraction module (709) samples the current of the secondary measurement winding (3), uses a digital phase-locked loop to lock the power frequency synchronous phase, and combines a sliding average and a first-order digital low-pass filter to extract the DC bias component from the power frequency, harmonic and DC superposition signals.

4. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 3, characterized in that, The main control unit (702) extracts the DC bias current component. Calculate the DC bias magnetomotive force: In the formula, The number of turns of the primary winding (2); According to Ohm's law for magnetic circuits, the bias flux and magnetomotive force satisfy: In the formula, The dynamic total magnetic reluctance of the iron core is strongly correlated with magnetic flux density B, operating temperature T, BH characteristics, and air gap size. Piecewise linearization of the magnetoresistive material: In the formula: This represents the average length of the magnetic circuit in the iron core. The permeability of free space, This represents the equivalent relative permeability of the iron core at the current magnetic flux density and temperature. For air gap reluctance; To counteract the unidirectional bias flux, the flux compensation winding (4) outputs a reverse counteracting magnetomotive force: ; The ideal excitation current of the flux compensation winding (4) is: In the formula, The number of turns of the flux compensation winding (4); The main control unit (702) adopts a PI closed-loop regulator, with zero magnetic flux as the control target, and adjusts the compensation winding drive current according to the magnetic flux error: In the formula, These are the proportional and integral adjustment coefficients, respectively; by suppressing model mismatch caused by hysteresis and eddy currents through closed-loop control, the unidirectional magnetization saturation caused by DC bias is dynamically eliminated.

5. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 4, characterized in that, The temperature sensor (8) collects the body temperature T of the composite main iron core (1), and the temperature-permeability coupling error correction algorithm unit (711) calls the factory-calibrated permeability-temperature fitting curve to perform polynomial temperature correction on the equivalent relative permeability of the iron core: In the formula, For reference calibration temperature, The initial relative permeability at the reference temperature. The calibration coefficient for high and low temperature tests is the first-order temperature coefficient of nanocrystalline materials. Value ; It will be updated in real time. Substituting back into the total magnetic reluctance formula: Substitute the total magnetic reluctance into the calculation, recalculate the ideal excitation current of the flux compensation winding (4), and complete the temperature coupling correction at the magnetic circuit level.

6. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 5, characterized in that, The main control unit (702) obtains the current measured temperature T of the iron core, retrieves the factory-calibrated ratio difference-temperature curve and angle difference-temperature curve, and performs digital correction of the amplitude and phase of the secondary current output by the secondary measurement winding (3): In the formula, These are the amplitude and phase of the original sampled current of the secondary winding, respectively. These represent the amplitude and phase of the output current after temperature drift compensation. The temperature correlation ratio difference This refers to the temperature-dependent angle difference; Through the above corrections, the current transformer meets the 0.2S level metering accuracy requirement across the entire temperature range of -40℃ to 85℃.

7. The wide-temperature dynamic AC / DC magnetic saturation-eliminating high-precision current transformer according to claim 1, characterized in that, The composite main iron core (1), primary winding (2), secondary measurement winding (3), magnetic flux compensation winding (4), magnetic flux acquisition sensing unit (6), integrated control unit (7) and temperature sensor (8) adopt an epoxy resin integrated vacuum casting encapsulation structure.

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