Electrical steel magnetism measuring device and measuring method thereof

Abstract

The invention discloses an electrical steel magnetism measuring device and a measuring method thereof, and the device comprises a magnetic conductometer, a primary winding receives an excitation signal to magnetize measured electrical steel, and a secondary winding induces the change of magnetic flux to output a secondary voltage signal; the analog-to-digital conversion module is used for collecting the secondary voltage signal and converting the secondary voltage signal into a digital feedback signal; the signal processing module is used for outputting a target waveform sequence according to the digital feedback signal and a preset reference waveform; the digital-to-analog conversion module is used for converting the target waveform sequence into a target waveform signal; and the power amplification module is used for amplifying the power of the target waveform signal, and outputting an excitation signal consistent with the waveform of the target waveform signal through voltage feedback and / or current feedback, so that the secondary voltage signal is consistent with the preset reference waveform. According to the invention, the problems that the output of the power amplifier is easy to distort and the high-resolution online volatility measurement is uncertain can be solved, and the consistency of waveform conditions and the test accuracy and efficiency when the magnetic performance of the tested electrical steel is tested are improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the application relates to the technical field of electrical steel, in particular to an electrical steel magnetic measuring device and a measuring method thereof. BACKGROUND

[0002] The steel industry belongs to the key basic industry of China, with the development of science and technology, the demand for electrical steel (also known as silicon steel) of the power industry, electric vehicle industry and the like is increasing, and the manufacturing technology and product quality of the electrical steel are important symbols for measuring the special steel production and science and technology development level of a country. For an automatic production line for realizing large-scale production, a steel plant realizes online monitoring of the magnetic property fluctuation of a steel strip in a rolling direction by quickly magnetizing and measuring the steel strip running on the production line, and provides an accurate and effective detection and evaluation method for quality control, grade selection and process level improvement of the steel plant.

[0003] The power amplifier output module of the traditional electrical steel magnetic measuring device does not have a waveform real-time feedback function, the waveform coefficient is large when measuring the iron loss corresponding to the high magnetic induction point of the electrical steel, and for the measurement scenes of high-speed sampling, multi-parameter rapid processing, high-speed measurement and multi-mode measurement, the power amplifier output is easy to be distorted, so that the actual measured iron loss performance parameter is poor, and the actual data comparison is affected.

[0004] The prior art adopts a secondary voltage sine feedback circuit to ensure that the secondary voltage waveform is sinusoidal, and the secondary voltage signal and the digital-to-analog conversion module output signal are amplified and fed back in waveform difference. The feedback mode can cope with the traditional low-resolution measurement scheme, but for the measurement scenes of high-speed sampling, multi-parameter rapid processing, high-speed measurement and multi-mode measurement, it cannot ensure the high-resolution online fluctuation measurement. SUMMARY

[0005] The technical problem solved by the embodiment of the application is to provide an electrical steel magnetic measuring device and a measuring method thereof, which can solve at least part of the defects existing in the prior art electrical steel magnetic measurement.

[0006] In a first aspect, the present application provides an electrical steel magnetic measurement device, comprising: a magnetic permeameter comprising a primary winding and a secondary winding, the primary winding receiving an excitation signal output by a power amplifier module to magnetize a measured electrical steel, the secondary winding sensing a change in magnetic flux and outputting a secondary voltage signal; an analog-to-digital conversion module configured to collect the secondary voltage signal and convert the secondary voltage signal into a digital feedback signal; a signal processing module comprising a waveform generator, configured to output a target waveform sequence based on the digital feedback signal and a preset reference waveform generated by the waveform generator; a digital-to-analog conversion module configured to convert the target waveform sequence into a target waveform signal; and a power amplifier module configured to power amplify the target waveform signal and output an excitation signal consistent with the target waveform signal in waveform through voltage feedback and / or current feedback to magnetize, so that the secondary voltage signal remains consistent with the preset reference waveform in waveform.

[0007] Optionally, the power amplifier module comprises: a differential operational amplifier unit configured to adjust the target waveform signal into a pre-stage driving signal; a feedback resistance switching unit having a plurality of feedback resistance ranges, configured to generate an output current conversion signal based on the excitation signal; a current feedback unit configured to generate a current feedback signal based on the excitation signal; a voltage feedback unit configured to generate a voltage feedback signal based on the excitation signal; and a driving operational amplifier unit configured to receive the pre-stage driving signal and generate the excitation signal consistent with the target waveform signal in waveform under the action of the current feedback signal and / or the voltage feedback signal.

[0008] Optionally, the power amplifier module further comprises: a stable zero feedback unit configured to generate a drift feedback signal input to the driving operational amplifier unit to eliminate a direct current component when the excitation signal has the direct current component.

[0009] Optionally, the stable zero feedback unit comprises a fourth operational amplifier, a first capacitor, a second resistor and a third resistor; a first end of the second resistor and a first input end of the driving operational amplifier unit are connected, a second end of the second resistor and an output end of the fourth operational amplifier and a first end of the first capacitor are connected, a second end of the first capacitor and an inverting input end of the fourth operational amplifier and a first end of the third resistor are connected, a second end of the third resistor and an output end of the feedback resistance switching unit are connected, and a non-inverting input end of the fourth operational amplifier is connected to a reference ground.

[0010] Optionally, the driving operational amplifier unit comprises a second operational amplifier, a power amplifier, a first control switch, a second capacitor, a first resistor, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; a first end of the fourth resistor is connected with an output end of the differential operational amplifier unit, an inverting input end of the second operational amplifier is connected with a second end of the fourth resistor, a first end of the first control switch, an output end of the current feedback unit and an output end of the voltage feedback unit, a non-inverting input end of the second operational amplifier is connected with a second end of the first resistor, and a first end of the first resistor is connected with a reference ground; an output end of the second operational amplifier is connected with a second end of the second capacitor and a positive electrode of the power amplifier, a first end of the second capacitor is connected with a second end of the fifth resistor, a first end of the fifth resistor is connected with a second end of the first control switch, a negative electrode of the power amplifier is connected with a second end of the sixth resistor and a first end of the seventh resistor, an output end of the power amplifier is connected with a second end of the seventh resistor and an input end of the feedback resistance switching unit, and a first end of the sixth resistor is connected with the reference ground.

[0011] Optionally, the current feedback unit comprises a third operational amplifier, a second control switch and an eighth resistor; an input end of the third operational amplifier is connected with an output end of the feedback resistance switching unit, an output end of the third operational amplifier is connected with a second end of the eighth resistor, a first end of the eighth resistor is connected with a second end of the second control switch, and a first end of the second control switch is connected with a second input end of the driving operational amplifier unit.

[0012] Optionally, the voltage feedback unit comprises a third control switch, a ninth resistor, a tenth resistor and an eleventh resistor; a first end of the tenth resistor is connected with an output end of the feedback resistance switching unit, a second end of the tenth resistor is connected with a first end of the eleventh resistor and a second end of the ninth resistor, a first end of the ninth resistor is connected with a second end of the third control switch, a first end of the third control switch is connected with a second input end of the driving operational amplifier unit, and a second end of the eleventh resistor is connected with a reference ground.

[0013] In a second aspect, the present application provides a method for measuring the magnetism of electrical steel, applied to the device for measuring the magnetism of electrical steel as described in the first aspect, comprising: step S100, generating a preset reference waveform by a waveform generator of a signal processing module, and converting the preset reference waveform into a target waveform sequence; step S200, converting the target waveform sequence into a target waveform signal by a digital-to-analog conversion module; step S300, power amplifying the target waveform signal by a power amplifier module, outputting an excitation signal to a primary winding of the permeameter, and magnetizing the measured electrical steel; step S400, sensing the change of magnetic flux by a secondary winding of the permeameter, and outputting a secondary voltage signal; step S500, collecting the secondary voltage signal by an analog-to-digital conversion module, and converting the secondary voltage signal into a digital feedback signal; step S600, analyzing and processing the digital feedback signal by the signal processing module, adjusting the target waveform sequence according to the difference between the digital feedback signal and the preset reference waveform; step S700, judging whether the secondary voltage signal is consistent with the preset reference waveform, and repeating steps S200 to S600 until the secondary voltage signal is consistent with the preset reference waveform; and step S800, calculating the magnetic parameters of the measured electrical steel according to the collected primary current signal and the secondary voltage signal.

[0014] Optionally, the power amplifying of the target waveform signal by the power amplifier module in step S300, the outputting of the excitation signal to the primary winding of the permeameter, and the magnetization of the measured electrical steel, comprises: adjusting the target waveform signal into a pre-stage driving signal by a differential operational amplifier unit; switching a feedback resistance switching unit to a corresponding feedback resistance range according to the excitation signal; power amplifying the pre-stage driving signal received by a driving operational amplifier unit, and outputting the excitation signal; detecting the output current of the excitation signal by a current feedback unit, generating a current feedback signal, and feeding back to the driving operational amplifier unit; detecting the voltage of the excitation signal by a voltage feedback unit, generating a voltage feedback signal, and feeding back to the driving operational amplifier unit; receiving the current feedback signal and the voltage feedback signal by the driving operational amplifier unit, adjusting the excitation signal, and making the excitation signal consistent with the target waveform signal in waveform.

[0015] Optionally, the power amplifying of the target waveform signal by the power amplifier module in step S300, the outputting of the excitation signal to the primary winding of the permeameter, and the magnetization of the measured electrical steel, further comprises: detecting the direct current component of the excitation signal by a stable zero feedback unit, and generating a drift feedback signal when there is a direct current offset; receiving the drift feedback signal by the driving operational amplifier unit, adjusting the excitation signal, and eliminating the direct current component.

[0016] The beneficial effect of the embodiment of the present application is that, unlike the prior art, the embodiment of the present application can solve the problems of easy distortion of power amplifier output and uncertainty of high-resolution online fluctuation measurement, and improve the consistency of waveform conditions, the accuracy of measurement and the efficiency when measuring the magnetic properties of the measured electrical steel. BRIEF DESCRIPTION OF DRAWINGS

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, which are schematic and not intended to be limiting of the embodiments, and in which like reference numerals designate similar items in the figures, in which: the drawings are not to scale.

[0018] Figure 1 is a structural schematic diagram of an electrical steel magnetic measurement device provided by the embodiment of the present application; Figure 2 is a structural schematic diagram of a power amplifier module provided by the embodiment of the present application; Figure 3 is a circuit schematic diagram of an electrical steel magnetic measurement device provided by the embodiment of the present application; Figure 4 is a flowchart of an electrical steel magnetic measurement method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element or one or more intervening elements can be present therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element or one or more intervening elements can be present therebetween. The terms "upper", "lower", "inner", "outer", "bottom", etc. used in the specification indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0020] Unless otherwise defined, all technical and scientific terms used in the specification have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification includes any and all combinations of one or more related listed items.

[0021] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0022] The technical solutions in the present application will be described below with reference to the drawings.

[0023] In some embodiments of the present application, as shown in Figure 1 A magnetic measurement device for electrical steel using a high-fidelity power amplifier module is provided. The device includes a magnetic permeameter 100, an analog-to-digital conversion module 200, a signal processing module 300, a digital-to-analog conversion module 400, and a power amplifier module 500.

[0024] Specifically, the magnetic permeameter 100 includes a magnetic yoke, a primary winding, and a secondary winding. The primary winding is used to receive an excitation signal output by the power amplifier module 500 to magnetize the measured electrical steel, and the secondary winding is used to induce a change in magnetic flux and output a secondary voltage signal. It is not difficult to understand that the magnetic permeameter 100 works based on the principle of electromagnetic induction. When an alternating excitation current is passed through the primary winding, a periodically changing magnetic field is generated around the measured electrical steel, causing the electrical steel to be periodically magnetized. The changing magnetic flux induces a voltage signal in the secondary winding that is proportional to the rate of change of the magnetic flux. The magnetic permeameter 100 achieves separation of excitation and detection through a double-winding structure, ensuring the accuracy of the measurement.

[0025] In some embodiments of the present application, the analog-to-digital conversion module 200 is used to collect the secondary voltage signal and convert it into a digital feedback signal. As an example but not limitation, the analog-to-digital conversion module 200 digitizes the secondary voltage signal through a high-precision analog-to-digital converter, converting the continuous analog voltage signal into a discrete digital signal sequence, providing a data basis for subsequent digital signal processing.

[0026] Specifically, the signal processing module 300 includes a waveform generator for outputting a target waveform sequence based on the digital feedback signal and a preset reference waveform generated by the waveform generator. The waveform generator has preset reference waveform parameters and can generate a standard sine waveform as a control reference. The signal processing module 300 analyzes the digital feedback signal provided by the analog-to-digital conversion module 200 through a digital signal processing algorithm, calculates the deviation between the actual secondary voltage waveform and the preset reference waveform, and adjusts the parameters of the target waveform sequence according to the deviation information, realizing closed-loop feedback control.

[0027] In some embodiments of the present application, the digital-to-analog conversion module 400 is used to convert the target waveform sequence into a target waveform signal. As an example but not limitation, the digital-to-analog conversion module 400 receives the digitized target waveform sequence output by the signal processing module 300, converts the digital signal into a continuous analog voltage signal through a digital-to-analog converter, and provides the power amplifier module 500 with a target waveform signal to be amplified. The conversion accuracy and bandwidth characteristics of the digital-to-analog conversion module 400 affect the waveform quality of the final excitation signal.

[0028] Specifically, the power amplifier module 500 is used to power amplify the target waveform signal and output an excitation signal consistent with the waveform of the target waveform signal for magnetization through voltage feedback and / or current feedback. The power amplifier module 500 has two optional feedback mechanisms built-in. Due to the inductive load, the built-in current feedback quickly locks to the target magnetic field operating point when the current feedback is locked; and when the voltage feedback unit is locked, the voltage feedback unit monitors the output voltage in real time and compares it with the target waveform signal. When a deviation between the output waveform and the target waveform is detected, the feedback unit automatically adjusts the power amplifier output to ensure that the excitation signal waveform is consistent with the target waveform signal. The power amplifier module 500 effectively suppresses the nonlinear distortion that may occur during power amplification through real-time feedback at the hardware level.

[0029] In some embodiments of the present application, the working process of the electrical steel magnetic measurement device is as follows: the signal processing module 300 generates a target waveform sequence, the digital-to-analog conversion module 400 converts it into a target waveform signal, the power amplifier module 500 power amplifies the target waveform signal and outputs an excitation signal to the magnetic conductance meter 100, the secondary winding of the magnetic conductance meter 100 outputs a secondary voltage signal, and the analog-to-digital conversion module 200 converts the secondary voltage signal into a digital feedback signal and feeds it back to the signal processing module 300. Through continuous feedback adjustment, the secondary voltage signal eventually achieves waveform consistency with the preset reference waveform, thereby ensuring the standardization of the measurement conditions and the comparability of the measurement results.

[0030] In some embodiments of the present application, as shown in Figure 2 The power amplifier module 500 includes a differential operational amplifier unit 510, a driving operational amplifier unit 520, a feedback resistor switching unit 530, a current feedback unit 540, a voltage feedback unit 550, and a steady zero feedback unit 560.

[0031] In some embodiments of the present application, as shown in Figure 3 The electrical steel magnetic measurement device includes a magnetic conductance meter 100, an analog-to-digital conversion module 200, a signal processing module 300, a digital-to-analog conversion module 400, and a power amplifier module 500. Figure 3 The detailed circuit composition of the power amplifier module is shown.

[0032] For specific references Figure 2 The differential operational amplifier unit 510 is used to adjust the target waveform signal into a pre-stage drive signal. The differential operational amplifier unit 510 receives the target waveform signal from the digital-to-analog converter module 400 and internally uses a high-precision differential operational amplifier for signal processing. Through its differential amplifier circuit structure, the differential operational amplifier unit 510 can effectively suppress common-mode noise and interference in the input signal, improving the signal-to-noise ratio. During signal adjustment, the differential operational amplifier unit 510 precisely adjusts the amplitude of the target waveform signal to a value that matches the entire feedback system. The adjusted pre-stage drive signal amplitude needs to maintain an appropriate proportional relationship with the feedback signal amplitudes generated by subsequent feedback units to ensure effective superposition and control of all signals at the signal aggregation node of the driving operational amplifier unit 520.

[0033] In some embodiments of this application, the feedback resistor switching unit 530 has multiple feedback resistor ranges for generating an output current conversion signal based on the excitation signal. By way of example and not limitation, the feedback resistor switching unit 530 is connected to the output of the drive operational amplifier unit 520, receiving the excitation signal and processing the current information therein. The feedback resistor switching unit 530 incorporates multiple sets of precision feedback resistors with different resistance values, and intelligent switching of the resistance range is achieved through a controllable switch.

[0034] Specifically, the feedback resistor switching unit 530's operating state is controlled by a software algorithm. Based on a complex proportional calculation principle, the software algorithm first predicts the required output current of the driving operational amplifier unit 520 according to the current measurement requirements and the magnetic properties of the electrical steel being measured. Then, combining the amplitude of the preceding drive signal and the desired current feedback signal amplitude, it determines the most suitable feedback resistor range for the current operating condition through proportional calculation. When the current in the excitation signal flows through the selected feedback resistor in the feedback resistor switching unit 530, according to Ohm's law V=IR, a voltage drop proportional to the current magnitude is generated across the feedback resistor, forming the output current conversion signal.

[0035] It's easy to understand that the choice of different feedback resistor ranges directly affects the amplitude characteristics of the output current conversion signal. When a small output current is expected, the software algorithm automatically switches to the high-resistance feedback resistor range. Under the same current conditions, a high-resistance resistor can generate a larger voltage drop, thus generating a larger amplitude output current conversion signal, improving the accuracy and reliability of small current detection. Conversely, when a large output current is expected, the software algorithm switches to the low-resistance feedback resistor range to avoid excessive power consumption across the high-resistance resistor due to large current, while ensuring that the output current conversion signal does not exceed the processing range of subsequent circuits and cause saturation distortion.

[0036] In some embodiments of this application, the current feedback unit 540 is used to generate a current feedback signal based on the excitation signal. By way of example and not limitation, the current feedback unit 540 receives an output current conversion signal from the feedback resistor switching unit 530, which is a voltage signal reflecting the magnitude of the current in the excitation signal. The current feedback unit 540 incorporates a high-precision operational amplifier, i.e. Figure 3 The third operational amplifier OP3 shown is used to condition the output current conversion signal into a current feedback signal of appropriate size.

[0037] Specifically, the third operational amplifier OP3 linearly amplifies and conditions the received output current conversion signal. The third operational amplifier OP3 features high input impedance, low offset voltage, and excellent linearity, enabling accurate amplification of the output current conversion signal without introducing significant distortion or error. The amplification factor is precisely designed to ensure that the amplitude of the output current feedback signal maintains a suitable match with the preceding drive signal and other feedback signals at the summing node of the drive operational amplifier unit 520.

[0038] It is easy to understand that amplitude matching of the current feedback signal is crucial. If the amplitude of the current feedback signal is too large, it will dominate the feedback control, causing the system to respond sluggishly to voltage changes and other control parameters; if the amplitude is too small, it will not provide sufficient current control capability, and the current accuracy of the system will be affected. Through the precise conditioning of the third operational amplifier OP3, the current feedback signal generated by the current feedback unit 540 can reflect the changes in current in the excitation signal in real time and accurately, providing a reliable current control basis for driving the operational amplifier unit 520.

[0039] In some embodiments of this application, the voltage feedback unit 550 is used to generate a voltage feedback signal based on the excitation signal. By way of example and not limitation, the voltage feedback unit 550 directly monitors the output voltage of the driving operational amplifier unit 520, i.e., the voltage of the excitation signal. The voltage feedback unit 550 internally employs a precision-designed resistor divider network, composed of high-precision resistors with low temperature coefficients, to ensure a stable voltage division ratio under different operating temperatures and time conditions.

[0040] Specifically, the amplitude of the voltage feedback signal also needs to maintain an appropriate proportional relationship with the preceding drive signal. Through precise resistance calculation and proportional design, the voltage feedback unit 550 ensures that when the voltage of the excitation signal changes, the corresponding change in the voltage feedback signal can produce a control effect of appropriate strength at the drive operational amplifier unit 520.

[0041] It is easy to understand that the voltage feedback unit 550 is mainly used to quickly respond to deviations in the output voltage. When the voltage of the excitation signal is detected to be lower or higher than the target value, the voltage feedback unit 550 immediately generates a corresponding positive or negative voltage feedback signal to guide the drive operational amplifier unit 520 to adjust the output to restore the correct voltage amplitude and waveform shape.

[0042] Specifically, the driver operational amplifier unit 520 receives the drive signal from the pre-amplifier stage and, under the influence of the current feedback signal and / or voltage feedback signal, generates an excitation signal consistent with the target waveform signal. The driver operational amplifier unit 520 is the core control and power amplification unit of the entire power amplifier module 500, undertaking the important functions of signal aggregation, feedback control, and power output. The driver operational amplifier unit 520 internally employs a high-performance power amplifier 521, possessing high current output capability, wide bandwidth characteristics, and fast response capability.

[0043] In some embodiments of this application, the operating principle of the driving operational amplifier unit 520 is based on the linear superposition of multiple input signals and negative feedback control theory. By way of example and not limitation, the driving operational amplifier unit 520 uses the pre-amplifier drive signal provided by the differential operational amplifier unit 510 as the primary control reference signal, while simultaneously receiving current feedback signals from the current feedback unit 540 and / or voltage feedback signals from the voltage feedback unit 550 at its input terminals. When the power amplifier system operates in an ideal state, i.e., when both the current and voltage of the excitation signal accurately track the target waveform, the driving operational amplifier unit 520 primarily performs linear amplification and output based on the pre-amplifier drive signal.

[0044] Specifically, when locking current feedback, if the output current of the excitation signal deviates from the target value, the feedback resistor switching unit 530 detects the current change and generates a corresponding output current conversion signal. The current feedback unit 540 converts this into a current feedback signal, which is superimposed on the input of the drive operational amplifier unit 520 to automatically adjust the output of the power amplifier 521 to correct the current deviation. When locking voltage feedback, if the output voltage of the excitation signal deviates from the target value, the voltage feedback unit 550 generates a voltage feedback signal to correct it, ensuring the accuracy of the voltage amplitude and waveform shape of the excitation signal.

[0045] In some embodiments of this application, the power amplifier module 500 further includes a zero-stability feedback unit 560, which generates a drift feedback signal and inputs it to the drive operational amplifier unit 520 to eliminate the DC component when a DC component exists in the excitation signal. By way of example and not limitation, the zero-stability feedback unit 560 is specifically designed to handle the long-term DC offset problem of the excitation signal, and functions in different time scales and frequency ranges with current feedback and / or voltage feedback to form a complete feedback control system.

[0046] Specifically, the zero-stability feedback unit 560 detects the DC and extremely low-frequency components in the excitation signal through a low-pass filter circuit. Internally, the zero-stability feedback unit 560 contains an RC low-pass filter composed of resistors and capacitors. Its cutoff frequency is designed to be much lower than the operating frequency of the electrical steel magnetism measurement, typically set in the range of a few hertz to tens of hertz, ensuring that only DC offset and extremely low-frequency drift are detected without affecting the normal AC measurement signal. When the zero-stability feedback unit 560 detects a DC offset in the excitation signal, it immediately generates a drift feedback signal with opposite polarity.

[0047] It's easy to understand that the amplitude of the drift feedback signal is precisely designed so that when it's input to the drive operational amplifier unit 520, it can effectively cancel the original DC offset without interfering with the AC signal. The zero-stability feedback unit 560 employs a long-time constant control characteristic, resulting in a relatively slow response speed. It primarily targets slowly changing DC offsets caused by factors such as temperature drift, device aging, and slow power supply variations. The zero-stability feedback unit 560, together with the fast-response current and voltage feedback, forms a complementary control on the time scale, ensuring that the excitation signal possesses both good transient response characteristics and excellent long-term stability.

[0048] In some embodiments of this application, the amplitude matching relationship of the feedback control system follows a uniform design principle and a precise proportional relationship. By way of example and not limitation, all feedback signals have mutually compatible amplitude ranges and frequency characteristics at the input summing node of the driving operational amplifier unit 520. The drift feedback signal amplitude of the zero-stabilization feedback unit 560 is designed to be a small proportion of the amplitude of the preceding drive signal, typically in the range of 1%-5%, ensuring that zero-stabilization adjustment can effectively eliminate DC offset without interfering with normal signal control.

[0049] Specifically, the amplitudes of the current feedback signal and the voltage feedback signal are designed to be a moderate proportion of the amplitude of the preceding drive signal, typically within the range of 5%-50%. The specific proportion of the current feedback signal depends on the resistance range selected by the feedback resistor switching unit 530 and the amplification factor of the third operational amplifier OP3 in the current feedback unit 540; the proportion of the voltage feedback signal in the voltage feedback unit 550 depends on the voltage division ratio of the voltage divider resistor network.

[0050] It's easy to understand that amplitude matching design is based on rigorous system stability analysis and control theory calculations. If the amplitude of a feedback signal is too large, it will lead to excessively high gain in the corresponding feedback loop, potentially causing system oscillations, response overshoot, or control instability. Conversely, if the amplitude of the feedback signal is too small, it cannot provide effective control, and the system's control accuracy, response speed, and anti-interference capability will be significantly affected. By using a unified matching principle based on the amplitude of the preceding drive signal, each feedback loop can achieve optimal control performance within its respective control frequency band and time scale, while maintaining good coordination among themselves.

[0051] For specific references Figure 3 The permeameter 100 includes a yoke, a primary winding, and a secondary winding. The yoke of the permeameter 100 is made of a soft magnetic material with high permeability. Both the primary and secondary windings are wound within the yoke. The electrical steel sheet being measured forms a closed magnetic circuit with the yoke of the permeameter as part of the magnetic circuit. The primary winding receives the excitation signal, where U1 and I1 represent the voltage and current of the excitation signal, respectively, generating an alternating magnetic field around the electrical steel sheet being measured to magnetize it. The secondary winding induces a change in magnetic flux. According to Faraday's law of electromagnetic induction, when the magnetic flux changes, an electromotive force (EMF), i.e., a secondary voltage U2, is induced in the secondary winding. This EMF is proportional to the rate of change of magnetic flux.

[0052] In some embodiments of this application, the apparatus may optionally include a transformer T1 for proportionally adjusting the voltage and current of the excitation signal output by the power amplifier module 500. By way of example and not limitation, when the voltage or current of the output signal of the power amplifier module 500 does not perfectly match the input requirements of the magnetometer 100, the transformer T1 adjusts the excitation signal to a suitable value through its transformation ratio before inputting it to the primary winding of the magnetometer 100. The transformation ratio of the transformer T1 is selected according to the specific measurement requirements and the characteristics of the electrical steel being measured, ensuring that the magnetometer 100 can operate under optimal excitation conditions. In particular, the transformer T1 also provides good isolation, preventing external signal interference.

[0053] In some embodiments of this application, the analog-to-digital conversion module 200 includes an input signal conditioner 210 and an analog-to-digital converter 220. By way of example and not limitation, the input signal conditioner 210 is connected to the secondary winding of the magnetometer 100 and is used to preprocess the secondary voltage signal. The input signal conditioner 210 internally includes a signal amplification circuit, a filtering circuit, and a level conversion circuit, capable of amplifying the weak voltage signal output from the secondary winding to the input range of the analog-to-digital converter 220, while filtering out high-frequency noise and interference signals. The analog-to-digital converter 220 converts the conditioned analog signal into a digital signal, providing a digitized feedback signal to the signal processing module 300.

[0054] Specifically, the signal processing module 300 integrates a high-performance FPGA chip and related digital signal processing circuits. The signal processing module 300 receives digital feedback signals from the analog-to-digital converter 220 and generates a preset reference waveform using a built-in waveform generator. As is easily understood, the waveform generator, based on digital signal processing algorithms, can generate high-precision standard sine waves, square waves, or other specific waveforms as control references. The signal processing module 300 calculates the waveform error and control parameters by comparing the digital feedback signal with the preset reference waveform, and adjusts the output target waveform sequence accordingly.

[0055] In some embodiments of this application, the digital-to-analog conversion module 400 includes an output signal conditioner 410 and a digital-to-analog converter 420. By way of example and not limitation, the digital-to-analog converter 420 receives a digitized target waveform sequence from the signal processing module 300 and converts it into a continuous analog voltage signal. The output signal conditioner 410 performs post-processing on the output of the digital-to-analog converter 420, including signal filtering, amplitude adjustment, and impedance matching, to ensure that the output target waveform signal has characteristics suitable for the input requirements of the power amplifier module 500.

[0056] Specifically, the detailed circuit implementation of the power amplifier module 500 includes a differential operational amplifier unit 510, a driver operational amplifier unit 520, a feedback resistor switching unit 530, a current feedback unit 540, a voltage feedback unit 550, and a zero-stability feedback unit 560. The differential operational amplifier unit 510 is implemented using a first operational amplifier OP1, which is configured in differential amplifier mode. Its OSC+ and OSC- input terminals receive differential target waveform signals from the digital-to-analog converter module 400, respectively. Through the linear amplification effect of the first operational amplifier OP1, the differential input signal is converted into a single-ended output pre-stage drive signal.

[0057] The driving operational amplifier unit 520 includes a second operational amplifier OP2 and a power amplifier 521, as well as a first control switch S1, a second capacitor C2, and multiple resistors. The second operational amplifier OP2 serves as a pre-amplifier; its inverting input is connected to the output of the differential operational amplifier unit 510 via a fourth resistor R4, and is also connected to the first terminal of the first control switch S1, the output of the current feedback unit 540, and the output of the voltage feedback unit 550, thus summarizing multiple signals. The non-inverting input of the second operational amplifier OP2 is connected to reference ground via a first resistor R1, which is used to set the input bias and gain characteristics of the second operational amplifier OP2.

[0058] In some embodiments of this application, the output terminal of the second operational amplifier OP2 is connected to the second terminal of the second capacitor C2 and the positive terminal of the power amplifier 521. By way of example and not limitation, the first terminal of the second capacitor C2 is connected to the second terminal of the fifth resistor R5, and the first terminal of the fifth resistor R5 is connected to the second terminal of the first control switch S1, forming a feedback network. The negative terminal of the power amplifier 521 is connected to the second terminal of the sixth resistor R6 and the first terminal of the seventh resistor R7. The output terminal of the power amplifier 521 is connected to the second terminal of the seventh resistor R7 and the input terminal of the feedback resistor switching unit 530. The first terminal of the sixth resistor R6 is connected to reference ground.

[0059] Specifically, the zero-stability feedback unit 560 includes a precise configuration of a fourth operational amplifier OP4, a first capacitor C1, a second resistor R2, and a third resistor R3. The first terminal of the second resistor R2 is connected to the inverting input of the second operational amplifier OP2 in the drive operational amplifier unit 520, and the second terminal of the second resistor R2 is connected to the output of the fourth operational amplifier OP4 and the first terminal of the first capacitor C1. The second terminal of the first capacitor C1 is connected to the inverting input of the fourth operational amplifier OP4 and the first terminal of the third resistor R3, and the second terminal of the third resistor R3 is connected to the output of the feedback resistor switching unit 530. The non-inverting input of the fourth operational amplifier OP4 is connected to reference ground.

[0060] The third resistor R3 and the first capacitor C1 in the zero-stability feedback unit 560 form an RC low-pass filter network, whose time constant τ = R3 × C1 determines the bandwidth characteristics of the zero-stability feedback. By appropriately selecting the values ​​of R3 and C1, the cutoff frequency of the filter can be set in the range of several hertz to tens of hertz, ensuring that feedback control is only applied to DC offset and extremely low frequency drift. The second resistor R2 and the third resistor R3 form a voltage divider network to achieve proportional attenuation, feeding back the detected DC offset to the drive operational amplifier unit 520 in an appropriate proportion, preventing the zero-stability feedback signal from being too strong and affecting normal signal control.

[0061] In some embodiments of this application, the current feedback unit 540 includes a third operational amplifier OP3, a second control switch S2, and an eighth resistor R8. By way of example and not limitation, the input terminal of the third operational amplifier OP3 is connected to the output terminal of the feedback resistor switching unit 530, receiving a voltage drop signal from the feedback resistor. The output terminal of the third operational amplifier OP3 is connected to the second terminal of the eighth resistor R8, the first terminal of the eighth resistor R8 is connected to the second terminal of the second control switch S2, and the first terminal of the second control switch S2 is connected to the inverting input terminal of the second operational amplifier OP2 in the drive operational amplifier unit 520.

[0062] Specifically, the third operational amplifier OP3 is configured as a voltage follower or non-inverting amplifier to buffer and amplify the small voltage drop signal across the feedback resistor. The eighth resistor R8 and the fourth resistor R4 form a voltage divider network, and their ratio R4 / R8 determines the amplitude of the current feedback signal at the input of the driving operational amplifier unit 520. The second control switch S2 controls the on / off state of the current feedback loop; it is closed when current feedback needs to be enabled and opened when current feedback needs to be disabled.

[0063] In some embodiments of this application, the voltage feedback unit 550 includes a third control switch S3, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11. By way of example and not limitation, the first end of the tenth resistor R10 is connected to the output terminal of the feedback resistor switching unit 530, i.e., the sampling point of the power amplifier output signal. The second end of the tenth resistor R10 is connected to the first end of the eleventh resistor R11 and the second end of the ninth resistor R9. The other end of the eleventh resistor R11 is grounded. The tenth resistor R10 and the eleventh resistor R11 form a voltage divider network, proportionally attenuating the power amplifier output voltage.

[0064] Specifically, the first terminal of the ninth resistor R9 is connected to the second terminal of the third control switch S3, and the first terminal of the third control switch S3 is connected to the inverting input terminal of the second operational amplifier OP2 in the drive operational amplifier unit 520. It is easy to understand that the voltage division ratio of the tenth resistor R10 and the eleventh resistor R11 determines the voltage sampling ratio, typically designed as an attenuation ratio of 5:1 to 30:1, attenuating the power amplifier's voltage output to a voltage range suitable for feedback processing. The ninth resistor R9 and the fourth resistor R4 constitute the amplitude adjustment network of the voltage feedback signal, and their proportional relationship affects the weight of the voltage feedback in the entire control system.

[0065] In some embodiments of this application, the feedback resistor switching unit 530 internally includes multiple precision resistors and corresponding switching circuits. By way of example and not limitation, the feedback resistor switching unit 530 may include resistors of different values ​​such as 0.1Ω, 1Ω, and 10Ω, and range switching is achieved through electronic switches or relays. After the signal processing module 300 performs a proportional calculation based on the expected output current, it instructs the feedback resistor switching unit 530 to select an appropriate feedback resistor range via a control signal.

[0066] Specifically, the magnetometer 100 is also connected to a twelfth resistor R12, a thirteenth resistor R13, and a fourteenth resistor R14 for signal conditioning. The twelfth resistor R12 serves as a sampling resistor for the primary current, connected in series in the primary winding circuit, converting the current signal into a voltage signal for acquisition by the analog-to-digital converter module 200. The thirteenth resistor R13 and the fourteenth resistor R14 form a secondary voltage attenuation network, attenuating the voltage signal of the secondary winding to the input range of the analog-to-digital converter module 200, thus preventing signal overload.

[0067] It should be noted that each operational amplifier in the circuit is equipped with an appropriate power supply. VCC, as marked in the diagram, represents the positive power supply, and VSS represents the negative power supply or ground potential. The power supply connections of each operational amplifier ensure that the circuit can handle both positive and negative bipolar signals.

[0068] In some embodiments of this application, the magnetic parameters of the electrical steel under test are calculated using the following measurement formulas. By way of example and not limitation, the formula for calculating the magnetic field strength H(t) is: H(t) = N1I(t) / Lm, where N1 is the number of turns in the primary winding, I(t) is the excitation current, and Lm is the equivalent magnetic circuit length of the sample under test. The formula for calculating the magnetic induction intensity J(t) is: J(t) = 1 / (N2×Ae) ∫U2(t)dt - μH(t), where N2 is the number of turns in the secondary winding, Ae is the equivalent cross-sectional area of ​​the sample under test, U2(t) is the secondary induced voltage, and μ is the air permeability.

[0069] Specifically, the iron loss Ps of the tested sample is calculated using the formula Ps = ∫J(t)dH(t) / ρ, where ρ is the density of the tested sample. By acquiring the primary current signal I(t) and the secondary voltage signal U2(t), and combining the geometric and material parameters of the tested sample, key magnetic parameters such as magnetic field strength, magnetic induction intensity, and iron loss are calculated in real time.

[0070] It should be noted that air flux compensation can be achieved through two methods: coil compensation or digital flux compensation. Coil compensation involves placing a compensation coil near the magnetometer to generate a magnetic field opposite to the air flux, thus canceling it out. Digital flux compensation calculates the effect of air flux using an algorithm in the signal processing module 300 and performs compensation processing in the digital domain. The formula for digital compensation is: Air flux compensation value = Primary current × Air permeability × Geometric coefficient; Compensated pure secondary voltage = Actual secondary voltage - Air flux compensation value.

[0071] With the above-mentioned electrical steel magnetic measurement device, the online measurement data refresh cycle can be shortened to 100ms. Combined with the maximum steel strip running speed of 300m / min, the measurement resolution can reach 0.5m. Through the dual control mechanism of hardware feedback and software feedback, it is ensured that excellent measurement accuracy and waveform quality can still be maintained under high-speed measurement conditions.

[0072] Specifically, the hardware feedback circuit can respond to and correct output deviations within microseconds, effectively suppressing transient distortion and nonlinear errors in the power amplifier output. The software feedback, leveraging the high-speed digital signal processing capabilities of the FPGA, can complete waveform analysis, error calculation, and parameter adjustment within a 100ms period, achieving waveform optimization and improved control precision.

[0073] The harmonic components of the primary coil signal of the magnetometer can be adjusted using software waveform algorithms, thereby achieving a sinusoidal waveform. Specifically, the signal processing module 300 performs Fast Fourier Transform (FFT) analysis on the acquired secondary voltage signal to identify the harmonic components in the signal. When 3rd, 5th, or higher harmonic distortion is detected in the secondary voltage, the corresponding compensation harmonic components are calculated and superimposed onto the target waveform sequence.

[0074] In some embodiments of this application, the specific implementation process of harmonic compensation is as follows: The signal processing module 300 first performs FFT analysis on the secondary voltage signal U2(t) to obtain the frequency domain representation U2(f). Then, it identifies the amplitude and phase information of the fundamental frequency component and each harmonic component. In order to make the secondary voltage output a pure sine wave, it is necessary to pre-add compensation harmonics with opposite phase to the primary excitation signal. The target waveform sequence after compensation is expressed as: Compensation target waveform = Reference sine wave + Σ(Compensation harmonic component), where the amplitude and phase of the compensation harmonic component are accurately calculated to ensure that the secondary output can approach a pure sine wave after the nonlinear processing of the magnetic circuit.

[0075] Unlike existing technologies, the embodiments of this invention can solve the problems of power amplifier output distortion and uncertainty in high-resolution online fluctuation measurements, improving the consistency of waveform conditions, accuracy, and efficiency when testing the magnetic properties of electrical steel. The coordinated operation of multiple feedback control mechanisms effectively solves the technical problems of waveform distortion, insufficient measurement accuracy, and limited dynamic range inherent in traditional measuring devices. Through deep integration of hardware and software, high-speed, high-precision, and highly stable online measurement capabilities for the magnetic properties of electrical steel are achieved.

[0076] Based on the above-described electrical steel magnetic measuring device, in some embodiments of this application, a method for measuring the magnetic properties of electrical steel is also provided, the flowchart of which is shown below. Figure 4 As shown, the specific steps include the following: Step S100: Generate a preset reference waveform through the waveform generator of the signal processing module, and convert the preset reference waveform into a target waveform sequence.

[0077] Specifically, the waveform generator built into the signal processing module 300 operates based on digital signal processing algorithms. It's easy to understand that the waveform generator generates a standard sine wave as a preset reference waveform according to the standard requirements for measuring the magnetic properties of electrical steel. The frequency of the preset reference waveform is typically set to the power frequency, such as 50Hz or 60Hz, and the amplitude is set according to the specific magnetic induction intensity requirements of the electrical steel being measured, such as the excitation conditions corresponding to 1.5T or 1.7T. In some embodiments, the parameters of the preset reference waveform can be dynamically adjusted according to different measurement modes and the characteristics of the material being measured.

[0078] In some embodiments of this application, the waveform generator discretizes a continuous preset reference waveform into a sequence of digital sampling points to form a target waveform sequence. By way of example and not limitation, the sampling frequency is typically set to hundreds to thousands of times the frequency of the measurement signal to ensure that the digitized target waveform sequence accurately represents the characteristics of the original analog waveform. Each data point in the target waveform sequence is precisely calculated, containing amplitude and phase information, providing an accurate digital reference for subsequent digital-to-analog conversion and signal control.

[0079] Step S200: Convert the target waveform sequence into the target waveform signal using the digital-to-analog converter module.

[0080] Specifically, the digital-to-analog converter module 400 receives the target waveform sequence from the signal processing module 300 and converts the digital signal into a continuous analog voltage signal through a high-precision digital-to-analog converter 420. The accuracy of the digital-to-analog converter directly affects the quality of the final excitation signal; therefore, a 16-bit or higher precision digital-to-analog converter is typically used. During the conversion process, digital sampling points are output sequentially at preset time intervals, and after filtering and amplification by the output signal conditioner 410, a smooth target waveform signal is formed.

[0081] In some embodiments of this application, the output signal conditioner 410 performs post-processing on the output of the digital-to-analog converter, including anti-aliasing filtering, amplitude calibration, and impedance matching. By way of example and not limitation, the anti-aliasing filter removes high-frequency spurious signals that may be generated during the digital-to-analog conversion process, ensuring that the output target waveform signal has good spectral purity. Amplitude calibration ensures that the actual amplitude of the target waveform signal is consistent with the design value, and impedance matching optimizes signal transmission efficiency.

[0082] Step S300: The target waveform signal is amplified by the power amplifier module, and the excitation signal is output to the primary winding of the magnetometer to magnetize the electrical steel under test.

[0083] Specifically, the power amplifier module 500 receives the target waveform signal and performs power amplification. It should be noted that the power amplification process is not merely simple signal amplification; it also includes a complex feedback control mechanism to ensure high fidelity of the output signal. The differential operational amplifier unit 510 first preprocesses the target waveform signal, adjusting the signal amplitude to match the requirements of the subsequent feedback system.

[0084] In some embodiments of this application, the power amplifier module 500 operates through a control mechanism of voltage feedback and / or current feedback. By way of example and not limitation, when voltage feedback is locked, when the drive operational amplifier unit 520 outputs an excitation signal, the voltage feedback unit 550 monitors the output voltage in real time and compares it with the target waveform signal to generate a voltage feedback signal for correcting voltage deviation. When current feedback is locked, the feedback resistor switching unit 530 selects an appropriate feedback resistor range according to the expected output current, and the current feedback unit 540 converts the detected current information into a current feedback signal for feedback control.

[0085] Step S400: The change in magnetic flux is induced by the secondary winding of the magnetometer, and a secondary voltage signal is output.

[0086] Specifically, when the excitation signal current I1 flows through the primary winding of the magnetometer 100, an alternating magnetic field is generated in the electrical steel being tested. According to Ampere's law, the magnetic field strength H(t) = N1I(t) / Lm, where N1 is the number of turns in the primary winding and Lm is the equivalent magnetic circuit length of the sample being tested. It is easy to understand that the electrical steel being tested is magnetized under the action of the alternating magnetic field, and the magnetic induction intensity changes with time, inducing an electromotive force in the secondary winding of the magnetometer.

[0087] In some embodiments of this application, the magnitude of the secondary voltage signal U2 is proportional to the rate of change of magnetic flux. By way of example and not limitation, according to Faraday's law of electromagnetic induction, the secondary induced voltage U2(t) = -N2dΦ / dt, where N2 is the number of turns in the secondary winding and Φ is the magnetic flux through the secondary winding. The secondary voltage signal contains complete information about the magnetic properties of the electrical steel being measured, including important parameters such as permeability, hysteresis characteristics, and magnetic saturation characteristics.

[0088] Step S500: Acquire the secondary voltage signal through the analog-to-digital converter module and convert it into a digital feedback signal.

[0089] Specifically, the input signal conditioner 210 in the analog-to-digital converter module 200 receives a voltage signal from the secondary winding of the magnetometer. It is easy to understand that the secondary voltage signal typically has a small amplitude and may contain noise interference, thus requiring amplification, filtering, and level adjustment. The input signal conditioner 210 amplifies the secondary voltage signal to the optimal input range of the analog-to-digital converter 220, while simultaneously removing high-frequency noise components using a low-pass filter.

[0090] In some embodiments of this application, the analog-to-digital converter 220 converts the conditioned analog signal into a digital feedback signal. By way of example and not limitation, the analog-to-digital converter uses the same sampling frequency as the target waveform sequence to ensure that the digital feedback signal remains synchronized with the target signal in the time domain. The converted digital feedback signal retains the amplitude, phase, and waveform details of the secondary voltage signal, providing an accurate data basis for subsequent digital signal processing and feedback control.

[0091] Step S600: The digital feedback signal is analyzed and processed by the signal processing module, and the target waveform sequence is adjusted according to the difference between the digital feedback signal and the preset reference waveform.

[0092] Specifically, the signal processing module 300 performs complex digital signal processing on the received digital feedback signal. The processing includes multiple steps such as waveform comparison and analysis, error calculation, frequency domain analysis, and control parameter generation. First, the digital feedback signal is compared with a preset reference waveform in the time domain to calculate key parameters such as amplitude error, phase error, and waveform distortion.

[0093] In some embodiments of this application, the signal processing module 300 also performs frequency domain analysis to identify harmonic distortion. By way of example and not limitation, the digital feedback signal is converted to the frequency domain using a Fast Fourier Transform (FFT) to analyze the amplitude and phase of the fundamental frequency component and each harmonic component. When harmonic distortion is detected in the secondary voltage signal, the corresponding compensation harmonic component is calculated and superimposed onto the target waveform sequence to achieve pre-distortion compensation control.

[0094] Specifically, air flux compensation is also implemented in this step. The signal processing module 300 calculates the influence of the air flux based on the primary current signal and the system's geometric parameters, and compensates for the feedback signal in the digital domain. The compensation formula is: Pure feedback signal = Original feedback signal - Primary current × Air permeability × Geometric coefficient.

[0095] Step S700: Determine whether the secondary voltage signal is consistent with the preset reference waveform.

[0096] Specifically, the signal processing module 300 performs a multi-dimensional consistency assessment of the secondary voltage signal after feedback adjustment and the preset reference waveform. The waveform consistency assessment needs to comprehensively consider multiple key parameters such as amplitude, phase, and waveform distortion to ensure the standardization of measurement conditions and the reliability of measurement results.

[0097] In some embodiments of this application, amplitude consistency is determined based on an average value comparison method. As an example, and not a limitation, the average value Uavg_actual of the secondary voltage signal and the effective value Uavg_target of a preset reference waveform are calculated, and the result is determined using the formula |Uavg_actual - Uavg_target| / Uavg_target<δ1, where δ1 is the amplitude error threshold. When the relative amplitude error is less than the set threshold, the amplitude is considered to meet the consistency requirements.

[0098] Phase consistency is determined by cross-correlation analysis. The signal processing module 300 calculates the phase difference Δφ between the secondary voltage signal and the preset reference waveform. When |Δφ| < δ2, the phase is considered consistent, where δ2 is the phase error threshold. Phase deviation directly affects the shape of the hysteresis loop and the accuracy of iron loss measurement.

[0099] Waveform distortion analysis is quantitatively evaluated using the Total Harmonic Distortion (THD) index. As an example, and not a limitation, a Fast Fourier Transform is performed on the secondary voltage signal to calculate the power of the fundamental component and each harmonic component. The total harmonic distortion is then calculated using the formula THD = √(∑Hi²) / H1 × 100%, where Hi is the amplitude of the i-th harmonic and H1 is the amplitude of the fundamental component. A waveform distortion threshold of δ3 is considered acceptable when THD < δ3.

[0100] Waveform coefficient consistency is an important indicator of waveform quality. The system calculates the waveform coefficients of the secondary voltage signal Ff_actual = Urms / Uavg and the waveform coefficients of the preset reference waveform Ff_target. The system judges the waveform coefficients by |Ff_actual - Ff_target| / Ff_target < δ4, where δ4 is the waveform coefficient error threshold. For a standard sine wave, Ff_target ≈ 1.1107.

[0101] The comprehensive judgment logic adopts a multi-condition AND logic gate approach. Only when the amplitude error, phase error, harmonic distortion, and waveform coefficient simultaneously meet their respective threshold requirements will it be determined that the secondary voltage signal is consistent with the preset reference waveform.

[0102] If the secondary voltage signal does not match the preset reference waveform, repeat steps S200 to S600 until the secondary voltage signal matches the preset reference waveform.

[0103] The excitation signal quality is gradually optimized through an iterative control process. In each iteration, the adjusted target waveform sequence undergoes a complete process of digital-to-analog conversion, power amplification, magnetization measurement, signal acquisition, and feedback analysis to form a closed-loop control circuit. As the number of iterations increases, the secondary voltage signal gradually approaches the preset reference waveform. When the waveform consistency reaches a preset threshold, control convergence is determined, and the system enters the steady-state measurement stage.

[0104] Step S800: Calculate the magnetic parameters of the electrical steel under test based on the collected primary current signal and secondary voltage signal.

[0105] Specifically, the current signal I(t) of the primary winding and the voltage signal U2(t) of the secondary winding are simultaneously acquired, and the magnetic parameters are calculated using the fundamental laws of electromagnetism. The magnetic field strength H(t) is calculated using the formula H(t) = N1I(t) / Lm. The magnetic induction intensity J(t) is obtained through integration: J(t) = 1 / (N2×Ae) ∫U2(t)dt - μH(t).

[0106] It is easy to understand that iron loss, as an important performance indicator of electrical steel, is calculated by the area of ​​the hysteresis loop. The formula for calculating iron loss is: Ps = ∫J(t)dH(t) / ρ, where the integration path is one complete magnetization cycle, and ρ is the density of the sample being tested. The system implements this calculation through a numerical integration algorithm to obtain the iron loss power per unit mass.

[0107] In some embodiments of this application, the system can also calculate other magnetic parameters. These include, by way of example and not limitation, parameters such as permeability μr = J / (μ0H), coercivity Hc, and remanent magnetic induction Jr. By analyzing the complete hysteresis loop, the magnetic properties of the electrical steel under test can be comprehensively evaluated.

[0108] In some embodiments of this application, step S300 specifically includes the following steps: Step S310: Adjust the target waveform signal into a pre-stage drive signal using a differential operational amplifier unit.

[0109] Specifically, the differential operational amplifier unit 510 receives the differential target waveform signal from the digital-to-analog converter module 400. The differential input mode can effectively suppress common-mode noise and power supply interference, improving signal quality. The first operational amplifier OP1 is configured in differential amplifier mode, and its gain is determined by the ratio of the external resistors, converting the differential input signal into a single-ended output pre-stage drive signal.

[0110] In some embodiments of this application, the amplitude adjustment of the pre-stage drive signal follows a system-level matching principle. By way of example and not limitation, the differential operational amplifier unit 510 precisely adjusts the amplitude of the target waveform signal to a value that matches the amplitude of the feedback signals generated by subsequent feedback units. The voltage division effect of the fourth resistor R4 is taken into account during the adjustment process to ensure that the pre-stage drive signal can provide a suitable control reference for driving the operational amplifier unit 520, while also creating conditions for the normal operation of each feedback loop.

[0111] Step S320: Based on the excitation signal, control the feedback resistor switching unit to switch to the corresponding feedback resistor range to output the corresponding output current conversion signal.

[0112] Specifically, the control of the feedback resistor switching unit 530 is based on intelligent judgment using software algorithms. The signal processing module 300, based on the current measurement mode, the magnetic characteristic parameters of the electrical steel being measured, and the expected excitation signal characteristics, predicts the magnitude of the current required to drive the operational amplifier unit 520 through proportional calculation. It is easy to understand that different measurement conditions require different amplitude excitation currents, thus requiring the feedback resistor switching unit 530 to select the appropriate feedback resistor range.

[0113] In some embodiments of this application, the selection logic for the feedback resistor switching is based on Ohm's law and the principle of feedback signal amplitude matching. As an example, and not a limitation, when the expected output current is small (e.g., less than 100mA), the software algorithm controls the switching to a high-resistance feedback resistor (e.g., 10Ω), ensuring that even a small current can generate a sufficiently large voltage drop across the feedback resistor, forming an output current conversion signal with a suitable amplitude. When the expected output current is large (e.g., exceeding 1A), the switching to a low-resistance feedback resistor (e.g., 0.1Ω) avoids excessive power consumption across the high-resistance resistor due to a large current, while ensuring that the output current conversion signal does not exceed the dynamic range of subsequent processing circuitry.

[0114] Specifically, when the current in the excitation signal flows through the selected feedback resistor, a corresponding voltage drop is generated according to V=IR, which is the output current conversion signal. The amplitude of this signal directly reflects the magnitude of the current in the excitation signal, providing an accurate detection basis for subsequent current feedback processing. The feedback resistor switching unit 530, through precise resistance value selection and reliable switching control, ensures that it can output an output current conversion signal with appropriate amplitude and good linearity under various operating conditions.

[0115] Step S330: Receive the drive signal from the previous stage through the drive operational amplifier unit, amplify the power, and output the excitation signal.

[0116] Specifically, the drive operational amplifier unit 520 receives the pre-stage drive signal from the differential operational amplifier unit 510 as the main control reference. Under ideal operating conditions, when all feedback signals are zero, the drive operational amplifier unit 520 mainly performs linear amplification and output based on the pre-stage drive signal.

[0117] In some embodiments of this application, the driving operational amplifier unit 520 adopts a two-stage amplification structure, including a cascaded configuration of a second operational amplifier OP2 and a power amplifier 521. By way of example and not limitation, the second operational amplifier OP2 serves as a voltage amplification stage, mainly responsible for signal summarization and primary amplification; the power amplifier 521 serves as a power output stage, possessing high current driving capability and able to provide sufficient excitation power for the magnetometer 100.

[0118] Step S340: The output current of the excitation signal is detected by the current feedback unit, a current feedback signal is generated and fed back to the drive operational amplifier unit.

[0119] Specifically, the current feedback unit 540 receives the output current conversion signal from the feedback resistor switching unit 530, which is a voltage representation of the current magnitude in the excitation signal. The third operational amplifier OP3 buffers and amplifies the output current conversion signal, conditioning it into a current feedback signal with an appropriate amplitude. It is easy to understand that the amplification factor of the third operational amplifier OP3 is precisely designed to ensure that the current feedback signal, the preceding drive signal, and other feedback signals maintain an appropriate proportional relationship at the convergence point of the drive operational amplifier unit 520.

[0120] In some embodiments of this application, the response characteristics of the current feedback are optimized for current control. By way of example and not limitation, the current feedback is mainly used to address current fluctuations caused by factors such as changes in load impedance and nonlinear characteristics of the magnetic circuit. When the output current of the excitation signal deviates from the target value, the current feedback unit 540 immediately detects the deviation and generates a corresponding current feedback signal, which is fed back to the input terminal of the drive operational amplifier unit 520 through the path of the eighth resistor R8 and the second control switch S2, forming a negative feedback control loop to automatically correct the current deviation.

[0121] Step S350: The voltage of the excitation signal is detected by the voltage feedback unit, a voltage feedback signal is generated and fed back to the drive operational amplifier unit.

[0122] Specifically, the voltage feedback unit 550 directly monitors the excitation signal voltage output by the drive operational amplifier unit 520. Through a precision voltage divider network formed by the tenth resistor R10 and the eleventh resistor R11, the high-amplitude excitation signal is attenuated to a voltage range suitable for feedback processing according to a preset ratio. It is easy to understand that the selection of the voltage division ratio is based on the voltage range of the excitation signal and the requirements of the feedback control system, and is typically designed as an attenuation ratio of 5:1 to 30:1.

[0123] In some embodiments of this application, the response characteristics of the voltage feedback unit 550 are optimized for voltage accuracy control. By way of example and not limitation, voltage feedback is primarily used to address voltage deviations caused by factors such as power amplifier gain changes, power supply fluctuations, and temperature drift. The attenuated voltage signal is fed back to the drive operational amplifier unit 520 via the path of the ninth resistor R9 and the third control switch S3. When the voltage of the excitation signal deviates from the target value, the voltage feedback unit 550 generates a corresponding positive or negative voltage feedback signal, guiding the drive operational amplifier unit 520 to adjust its output to restore the correct voltage amplitude.

[0124] Step S360: Adjust the current feedback signal or voltage feedback signal received by the drive operational amplifier unit in real time to make the waveform of the excitation signal consistent with the target waveform signal.

[0125] Specifically, the drive operational amplifier unit 520 receives the preceding drive signal, current feedback signal, or voltage feedback signal at its input terminal to achieve linear superposition and integrated control of multiple signals. It is easy to understand that each signal is summed at the inverting input terminal of the second operational amplifier OP2, and according to the principle of virtual short and virtual open circuits, the summed overall control signal determines the output characteristics of the drive operational amplifier unit 520.

[0126] In some embodiments of this application, the feedback mechanism plays different roles in different control dimensions. By way of example and not limitation, current feedback and voltage feedback have different frequency response characteristics and control priorities. Current feedback mainly focuses on the accuracy of the output current, has a fast response speed, and can promptly correct current fluctuations caused by load changes; voltage feedback mainly focuses on the stability of the output voltage and the distortion of the voltage output waveform.

[0127] Step S370: The DC component of the excitation signal is detected by the zero-stability feedback unit, and a drift feedback signal is generated when there is a DC offset.

[0128] Specifically, the zero-stability feedback unit 560 detects the DC and extremely low-frequency components in the excitation signal through a low-pass filter circuit. The RC low-pass filter, composed of the third resistor R3 and the first capacitor C1, has a cutoff frequency much lower than the operating frequency of the measurement signal, effectively separating the DC offset and the AC measurement signal. It is easy to understand that when there is a DC offset in the excitation signal, this offset component can pass through the low-pass filter and be detected by the fourth operational amplifier OP4.

[0129] In some embodiments of this application, the zero-stability feedback unit 560 employs a long-time constant control characteristic. By way of example and not limitation, the time constant of the zero-stability feedback is typically designed to be on the order of seconds to minutes, primarily targeting slow DC offsets caused by factors such as temperature drift, device aging, and slow power supply variations. When a DC offset is detected, the fourth operational amplifier OP4 generates a drift feedback signal with opposite polarity. The amplitude of this signal is adjusted by a voltage divider network of the second resistor R2 and the third resistor R3 to ensure that the DC offset is effectively eliminated without interfering with normal AC signal control.

[0130] Step S380: Receive the drift feedback signal through the driving operational amplifier unit, and work together with the current feedback signal and / or voltage feedback signal to eliminate the DC component of the excitation signal.

[0131] Specifically, the drift feedback signal is input to the inverting input of the driving operational amplifier unit 520 through the path of the second resistor R2, and is aggregated at the same node with the current feedback signal and / or voltage feedback signal. It is easy to understand that the three feedback signals operate at different time scales and frequency ranges, forming a complete feedback control system. The drift feedback signal mainly operates in the DC and extremely low frequency range, while the current feedback and / or voltage feedback mainly operate in the frequency range of the measured signal.

[0132] In some embodiments of this application, feedback control achieves comprehensive quality control of the excitation signal. By way of example and not limitation, current feedback corrects current deviations to ensure that the magnetometer receives an accurate excitation current; voltage feedback corrects voltage deviations to ensure the accuracy of the excitation signal amplitude.

[0133] As an example and not a limitation, this embodiment achieves high-fidelity power amplification of the power amplifier module through a feedback control mechanism, effectively solving technical problems such as output distortion, poor long-term stability, and limited dynamic range of traditional power amplifiers. Through the comprehensive application of differential signal processing, intelligent resistor switching, dual real-time feedback, and long-term zero-stability control, it ensures that the excitation signal can accurately and stably track the target waveform, providing reliable technical support for the precise measurement of the magnetic properties of electrical steels.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above. For the sake of brevity, they are not provided in detail; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A magnetic measuring device for electrical steel, characterized in that, include: A permeameter includes a primary winding and a secondary winding. The primary winding receives the excitation signal output by the power amplifier module to magnetize the electrical steel under test, and the secondary winding senses the change in magnetic flux and outputs a secondary voltage signal. An analog-to-digital converter module is used to acquire the secondary voltage signal and convert the secondary voltage signal into a digital feedback signal; A signal processing module including a waveform generator is used to output a target waveform sequence based on the digital feedback signal and a preset reference waveform generated by the waveform generator; A digital-to-analog converter module is used to convert the target waveform sequence into a target waveform signal; The power amplifier module is used to amplify the target waveform signal and magnetize it by outputting an excitation signal with the same waveform as the target waveform signal through voltage feedback and / or current feedback, so that the secondary voltage signal keeps the waveform consistent with the preset reference waveform.

2. The apparatus according to claim 1, characterized in that, The power amplifier module includes: A differential operational amplifier unit is used to adjust the target waveform signal into a pre-stage drive signal; The feedback resistor switching unit has multiple feedback resistor ranges and is used to generate an output current conversion signal according to the excitation signal. A current feedback unit is used to generate a current feedback signal based on the excitation signal; A voltage feedback unit is used to generate a voltage feedback signal based on the excitation signal; The driving operational amplifier unit is used to receive the pre-stage driving signal and, under the action of the current feedback signal and / or the voltage feedback signal, generate the excitation signal that is consistent with the waveform of the target waveform signal.

3. The apparatus according to claim 2, characterized in that, The power amplifier module also includes: The zero-stability feedback unit is used to generate a drift feedback signal and input it to the drive operational amplifier unit when the excitation signal has a DC component, so as to eliminate the DC component.

4. The apparatus according to claim 3, characterized in that, The zero-stability feedback unit includes a fourth operational amplifier, a first capacitor, a second resistor, and a third resistor; The first end of the second resistor is connected to the first input terminal of the driving operational amplifier unit, the second end of the second resistor is connected to the output terminal of the fourth operational amplifier and the first end of the first capacitor, the second end of the first capacitor is connected to the inverting input terminal of the fourth operational amplifier and the first end of the third resistor, the second end of the third resistor is connected to the output terminal of the feedback resistor switching unit, and the non-inverting input terminal of the fourth operational amplifier is connected to reference ground.

5. The apparatus according to claim 2, characterized in that, The driving operational amplifier unit includes a second operational amplifier, a power amplifier, a first control switch, a second capacitor, a first resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor; The first end of the fourth resistor is connected to the output end of the differential operational amplifier unit. The inverting input end of the second operational amplifier is connected to the second end of the fourth resistor, the first end of the first control switch, the output end of the current feedback unit, and the output end of the voltage feedback unit. The non-inverting input end of the second operational amplifier is connected to the second end of the first resistor. The first end of the first resistor is connected to reference ground. The output terminal of the second operational amplifier is connected to the second terminal of the second capacitor and the positive terminal of the power amplifier. The first terminal of the second capacitor is connected to the second terminal of the fifth resistor. The first terminal of the fifth resistor is connected to the second terminal of the first control switch. The negative terminal of the power amplifier is connected to the second terminal of the sixth resistor and the first terminal of the seventh resistor. The output terminal of the power amplifier is connected to the second terminal of the seventh resistor and the input terminal of the feedback resistor switching unit. The first terminal of the sixth resistor is connected to reference ground.

6. The apparatus according to claim 2, characterized in that, The current feedback unit includes a third operational amplifier, a second control switch, and an eighth resistor; The input terminal of the third operational amplifier is connected to the output terminal of the feedback resistor switching unit, the output terminal of the third operational amplifier is connected to the second terminal of the eighth resistor, the first terminal of the eighth resistor is connected to the second terminal of the second control switch, and the first terminal of the second control switch is connected to the second input terminal of the driving operational amplifier unit.

7. The apparatus according to claim 2, characterized in that, The voltage feedback unit includes a third control switch, a ninth resistor, a tenth resistor, and an eleventh resistor; The first end of the tenth resistor is connected to the output end of the feedback resistor switching unit, the second end of the tenth resistor is connected to the first end of the eleventh resistor and the second end of the ninth resistor, the first end of the ninth resistor is connected to the second end of the third control switch, the first end of the third control switch is connected to the second input end of the drive operational amplifier unit, and the second end of the eleventh resistor is connected to the reference ground.

8. A method for measuring the magnetism of electrical steel, applied to the electrical steel magnetism measuring device as described in any one of claims 1-7, characterized in that, include: Step S100: Generate a preset reference waveform through the waveform generator of the signal processing module, and convert the preset reference waveform into a target waveform sequence; Step S200: Convert the target waveform sequence into a target waveform signal using a digital-to-analog converter module; Step S300: The target waveform signal is amplified by the power amplifier module, and the excitation signal is output to the primary winding of the magnetometer to magnetize the electrical steel under test. Step S400: The change in magnetic flux is induced by the secondary winding of the magnetometer, and a secondary voltage signal is output; Step S500: Acquire the secondary voltage signal through the analog-to-digital converter module and convert the secondary voltage signal into a digital feedback signal; Step S600: The digital feedback signal is analyzed and processed by the signal processing module, and the target waveform sequence is adjusted according to the difference between the digital feedback signal and the preset reference waveform; Step S700: Determine whether the secondary voltage signal is consistent with the preset reference waveform. If they are inconsistent, repeat steps S200 to S600 until the secondary voltage signal is consistent with the preset reference waveform. Step S800: Calculate the magnetic parameters of the electrical steel under test based on the acquired primary current signal and the secondary voltage signal.

9. The method according to claim 8, characterized in that, In step S300, the target waveform signal is amplified by a power amplifier module, and an excitation signal is output to the primary winding of the magnetometer to magnetize the electrical steel under test, including: The target waveform signal is adjusted into a pre-stage drive signal using a differential operational amplifier unit; According to the excitation signal, the feedback resistor switching unit is controlled to switch to the corresponding feedback resistor range; The driver operational amplifier unit receives the pre-stage drive signal, amplifies it, and outputs the excitation signal. The current feedback unit detects the output current of the excitation signal, generates a current feedback signal, and feeds it back to the drive operational amplifier unit. The voltage of the excitation signal is detected by the voltage feedback unit, a voltage feedback signal is generated and fed back to the drive operational amplifier unit; The driving operational amplifier unit receives the current feedback signal and the voltage feedback signal, and adjusts the excitation signal to make the excitation signal consistent with the target waveform signal.

10. The method according to claim 9, characterized in that, In step S300, the target waveform signal is amplified by a power amplifier module, and an excitation signal is output to the primary winding of the magnetometer to magnetize the electrical steel under test. This step also includes: The DC component of the excitation signal is detected by a zero-stability feedback unit, and a drift feedback signal is generated when a DC offset exists. The drive operational amplifier unit receives the drift feedback signal and adjusts the excitation signal to eliminate the DC component.

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