A power amplifier gain control method and system for magnetic property measurements

Abstract

This invention belongs to the field of magnetic material measurement technology, and particularly relates to a power amplifier gain control method and system for magnetic characteristic measurement. The method includes the following steps: calculating the instantaneous rate of change of magnetization impedance at each moment, where the instantaneous rate of change of magnetization impedance is positively correlated with the time derivative of the ratio of output voltage to excitation current; calculating the dynamic load margin at each moment, where the dynamic load margin is negatively correlated with the instantaneous rate of change of magnetization impedance and positively correlated with the difference between the power amplifier's supply rail voltage and output voltage amplitude; determining the gain scaling factor at each moment, where the gain scaling factor is positively correlated with the dynamic load margin and its value ranges between a set upper and lower gain limit; and using the gain scaling factor to adjust the drive voltage command in real time to control the power amplifier's output gain, which can effectively improve the accuracy of power amplifier gain control for magnetic characteristic measurement.

Description

Technical Field

[0001] This invention belongs to the field of magnetic material measurement technology, and in particular relates to a power amplifier gain control method and system for measuring magnetic properties. Background Technology

[0002] In the fields of materials science and magnetic physics research, accurate characterization of the magnetic properties of magnetic loads such as nanocrystalline soft magnetic materials and silicon steel sheets (e.g., obtaining iron loss, hysteresis loops, etc.) is a core technical requirement. Such experiments typically utilize a power amplifier to amplify the waveform generated by a signal generator, driving an excitation coil to produce an alternating magnetic field, thereby enabling the magnetic flux density inside the magnetic sample to reach a preset amplitude.

[0003] However, magnetic materials exhibit significant nonlinear physical characteristics and require measurements spanning extremely wide areas, ranging from small-signal regions at the millitalas level to deep saturation regions. Existing techniques for controlling power amplifiers typically employ fixed-gain control or adjustment algorithms based on simple linear feedback, assuming a relatively stable load environment.

[0004] This traditional control method suffers from severe gain mismatch when dealing with magnetic measurements over a wide dynamic range. On the one hand, in the small-signal measurement region, limited by a fixed gain configuration, the system's signal-to-noise ratio is low, and weak effective signals are easily drowned out by background noise, resulting in insufficient measurement accuracy. On the other hand, when the material is magnetized to near saturation, the internal magnetic domains shift, causing a sharp nonlinear drop in load impedance, resulting in a collapse. At this point, relying solely on linear feedback or a fixed gain cannot respond promptly to this instantaneous impedance change at the physical level, easily triggering power amplifier output voltage clipping, waveform distortion, or self-oscillation, thereby triggering overload protection. This makes it difficult to balance measurement accuracy and system stability across the entire measurement range.

[0005] Therefore, how to accurately achieve power amplifier gain control for magnetic characteristic measurement is a problem that needs to be solved. Summary of the Invention

[0006] To address the technical problem of accurately controlling the gain of a power amplifier for magnetic characteristic measurement, this invention provides a method and system for controlling the gain of a power amplifier for magnetic characteristic measurement.

[0007] In a first aspect, the present invention provides a power amplifier gain control method for magnetic characteristic measurement, employing the following technical solution:

[0008] A method for gain control of a power amplifier for magnetic characteristic measurement, comprising the following steps:

[0009] Obtain the output voltage and excitation current of the power amplifier; calculate the instantaneous rate of change of magnetization impedance at each moment. The instantaneous rate of change of magnetization impedance is positively correlated with the time derivative of the ratio of output voltage to excitation current, and negatively correlated with the product of the set experimental frequency and the peak value of the target magnetic flux density corresponding to the power amplifier; calculate the dynamic load margin at each moment. The dynamic load margin is negatively correlated with the instantaneous rate of change of magnetization impedance, and positively correlated with the difference between the power supply rail voltage and the output voltage amplitude of the power amplifier; determine the gain scaling factor at each moment. The gain scaling factor is positively correlated with the dynamic load margin, and its value ranges between the set upper and lower gain limits; use the gain scaling factor to adjust the drive voltage command in real time to control the output gain of the power amplifier.

[0010] This invention provides a power amplifier gain control method for magnetic characteristic measurement, which can effectively improve the accuracy of power amplifier gain control and thus improve the efficiency of magnetic characteristic measurement. In implementing power amplifier gain control, this invention adaptively adjusts the power amplifier gain according to drastic changes in load characteristics by calculating the instantaneous rate of change of magnetization impedance and dynamic load margin in real time. Compared with traditional fixed gain or simple voltage feedback control, this method effectively solves the problems of power amplifier output saturation, waveform clipping, or distortion caused by nonlinear changes in magnetoimpedance during magnetic characteristic measurement (especially when the sample tends to saturate). While ensuring measurement accuracy, it maximizes the utilization of the power amplifier's linear dynamic range, improving system stability and safety.

[0011] According to the present invention, a power amplifier gain control method for measuring magnetic characteristics includes obtaining the output voltage and excitation current of the power amplifier by: hardware synchronizing the sampling circuit with the signal generator to ensure the phase consistency between the excitation current signal and the induced voltage signal, thereby obtaining the output voltage and excitation current of the power amplifier at each moment.

[0012] This invention eliminates the phase error between the excitation current signal and the induced voltage signal at the physical level by using a hardware synchronous sampling circuit and a signal generator. Compared to methods that rely solely on software synchronous or asynchronous sampling, this method effectively improves the accuracy of phase measurement, thereby ensuring the precision of subsequent instantaneous impedance change rate calculation and providing a reliable data foundation for high-precision gain control.

[0013] According to the present invention, a power amplifier gain control method for measuring magnetic characteristics includes obtaining the output voltage and excitation current of the power amplifier, further comprising: connecting an isolation transformer with a turns ratio of 1:1 between the power amplifier and the excitation coil to suppress DC bias components.

[0014] This invention introduces an isolation transformer with a 1:1 turns ratio between the power amplifier and the excitation coil, effectively isolating and suppressing the DC bias component caused by circuit asymmetry or temperature drift. Compared to direct coupling drive, this design avoids the DC component from causing unexpected magnetization shift or saturation of the magnetic sample, and can further improve the accuracy, repeatability, and protection of the sample under test in AC magnetic property measurements.

[0015] According to the present invention, a power amplifier gain control method for measuring magnetic properties includes calculating the instantaneous magnetization impedance change rate at each moment, comprising:

[0016] ;

[0017] For a moment The instantaneous rate of change of magnetization impedance, For a moment The induced voltage, For a moment The excitation current, To prevent constants with a denominator of zero, To set the experimental frequency, The target magnetic flux density peak value corresponding to the power amplifier. It is the absolute value symbol.

[0018] This invention provides a precise method for calculating the instantaneous rate of change of magnetization impedance. It normalizes the result by combining the derivative of the ratio of induced voltage to excitation current with the target magnetic flux density. Compared to simple judgments based solely on voltage or current amplitude, this method can promptly capture the dynamic trend of a sharp decrease in impedance of magnetic materials near the saturation region, providing a highly sensitive control index for gain adjustment.

[0019] According to the present invention, a power amplifier gain control method for measuring magnetic characteristics is provided. The method for obtaining the target magnetic flux density peak value corresponding to the power amplifier includes: obtaining the maximum output voltage and the maximum excitation current from the hardware limits of the power amplifier; obtaining the magnetic flux density corresponding to the maximum output voltage according to Faraday's law of electromagnetic induction, wherein the maximum output voltage is positively correlated with the magnetic flux density; obtaining the magnetic flux density corresponding to the maximum excitation current according to Ampere's theorem, wherein the maximum excitation current is positively correlated with the magnetic flux density; and taking the minimum value between the magnetic flux density corresponding to the maximum output voltage and the magnetic flux density corresponding to the maximum excitation current as the target magnetic flux density peak value corresponding to the power amplifier.

[0020] According to the present invention, a power amplifier gain control method for magnetic characteristic measurement includes calculating the dynamic load margin at each moment, comprising:

[0021] ;

[0022] For a moment Dynamic load-bearing capacity margin. This is the maximum power rail voltage of the power amplifier. For a moment The output voltage, For a moment The output voltage amplitude, The impedance fluctuation weighting coefficient is used. For a moment The instantaneous rate of change of magnetization impedance, For An exponential function with base 0.

[0023] This invention constructs a precise dynamic load margin calculation formula, which includes a weighted average of the power supply rail voltage difference and impedance fluctuation. Compared to static voltage margin assessment, this method uses an exponential function to amplify the weight of the impact of drastic impedance fluctuations on the margin, enabling the margin assessment value to be tightened more quickly when the magnetic impedance drops rapidly. This allows for advance control space and prevents the output voltage from touching the power supply rail, thus preventing signal distortion.

[0024] According to the present invention, a power amplifier gain control method for magnetic characteristic measurement is provided, wherein determining the gain scaling factor at each moment includes:

[0025] ;

[0026] For a moment The target gain scaling factor, , These are the lower and upper limits of the gain adjustment ratio, respectively. The slope factor of the curve. This is the offset of the curve center. For a moment Dynamic load-bearing capacity margin. is a natural constant; among which, the lower gain limit, upper gain limit, curve slope factor, and curve center offset are obtained through experimental calibration.

[0027] According to the present invention, a power amplifier gain control method for magnetic characteristic measurement is provided, wherein the real-time adjustment of the drive voltage command using a gain scaling factor includes: using the product of the gain scaling factor at the current moment and the drive voltage command as the final execution command value at the current moment.

[0028] According to the present invention, a power amplifier gain control method for magnetic characteristic measurement is provided, wherein controlling the output gain of the power amplifier includes: mapping the final execution instruction value to a programmable instruction and injecting it into the register of the power amplifier in real time, and adjusting the output level through a numerically controlled gain circuit.

[0029] Secondly, the present invention provides a power amplifier gain control system for magnetic characteristic measurement, which adopts the following technical solution:

[0030] A power amplifier gain control system for magnetic characteristic measurement includes a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the aforementioned power amplifier gain control method for magnetic characteristic measurement is implemented.

[0031] By adopting the above technical solution, a computer program for the power amplifier gain control method for magnetic characteristic measurement is generated and stored in a memory for loading and execution by a processor. This allows for the creation of a terminal device based on the memory and processor, facilitating its use.

[0032] The present invention has the following technical effects:

[0033] Based on the above technical solution, this invention provides a power amplifier gain control method and system for magnetic characteristic measurement. By calculating the instantaneous rate of change of magnetization impedance and dynamic load margin in real time, the gain of the power amplifier can be adaptively adjusted according to drastic changes in load characteristics. Compared with traditional fixed gain or simple voltage feedback control, this method effectively solves the problems of power amplifier output saturation, waveform clipping, or distortion caused by nonlinear changes in magnetoimpedance when the sample tends to saturate during magnetic characteristic measurement. While ensuring measurement accuracy, it maximizes the use of the linear dynamic range of the power amplifier, effectively improving the accuracy of the measurement results, thereby improving the stability and safety of the measurement process. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a power amplifier gain control method for magnetic characteristic measurement provided in an embodiment of the present invention.

[0035] Figure 2 A schematic diagram of the instantaneous rate of change of magnetization impedance provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram illustrating the dynamic load-bearing margin variation provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram comparing the effects of dynamic gain and fixed gain control in an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram illustrating a comprehensive analysis of hysteresis loop and control effect provided in an embodiment of the present invention. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] This invention discloses a power amplifier gain control method for magnetic property measurement. By dynamically adjusting the gain, it can effectively improve the full-range accuracy and precision of the measurement data while balancing the high signal-to-noise ratio requirement under low magnetic flux density and the stability requirement in the deep saturation region.

[0041] Please see details. Figure 1 As shown, Figure 1 This is a flowchart illustrating a power amplifier gain control method for magnetic characteristic measurement provided in an embodiment of the present invention. The method specifically includes the following steps:

[0042] S1: Obtain the output voltage and excitation current of the power amplifier.

[0043] It should be noted that the construction of the experimental environment and the initialization of the target waveform are the physical prerequisites for realizing automated magnetic property measurement. In the process of magnetic property measurement based on power amplifier, the amplitude of voltage wave signals such as sine waves, triangular waves, symmetrical rectangular waves, and asymmetrical rectangular waves generated by the signal generator is adjusted and amplified by the amplifier to make the magnetic flux density inside the nanocrystalline magnetic ring reach the expected amplitude, thereby measuring the vibration and magnetization characteristics of the nanocrystalline magnetic ring under different magnetic flux densities, excitation frequencies, and excitation waveforms.

[0044] Specifically, when measuring magnetic properties, test equipment can be prepared in advance, such as a signal generator, power amplifier, voltage probe, oscilloscope, high-frequency current probe, and accelerometer. During the measurement process, the excitation source is generated by the signal generator and connected to the magnetic ring under test through the secondary side of the transformer. The induced voltage can be obtained by the oscilloscope, while the excitation current can be measured by the high-frequency current probe.

[0045] Furthermore, the characterization of magnetic materials, such as nanocrystalline soft magnetic materials and silicon steel sheets, must be performed at specific frequencies and preset magnetic flux density amplitudes. By constructing discretized waveform sequences, the control system can obtain a real-time comparison benchmark, thereby determining the degree of distortion in the output signal. In addition, since magnetic materials are extremely sensitive to DC components, physical DC isolation can effectively reduce the possibility that software correction alone cannot eliminate the inherent slight zero-point bias of the power amplifier output stage, thus reducing the possibility of asymmetrical offset of the hysteresis loop leading to inflated loss measurement results. Simultaneously, hardware synchronization between the sampling circuit and the signal generator is crucial. Lack of synchronization will cause phase distortion in the acquired excitation current and induced voltage, resulting in serious physical logic errors in the subsequently calculated energy loss.

[0046] Based on this, the embodiments of the present invention use hardware synchronization and physical isolation to ensure the purity and phase consistency of the original signal, providing high-fidelity data input for subsequent impedance feature extraction.

[0047] For example, in an embodiment of the present invention, obtaining the output voltage and excitation current of a power amplifier includes: hardware synchronizing the sampling circuit with a signal generator to ensure phase consistency between the excitation current signal and the induced voltage signal, thereby obtaining the output voltage and excitation current of the power amplifier at each moment.

[0048] For example, in an embodiment of the present invention, obtaining the output voltage and excitation current of the power amplifier further includes: connecting an isolation transformer with a turns ratio of 1:1 between the power amplifier and the excitation coil to suppress the DC bias component.

[0049] Thus, by synchronously acquiring and DC-isolated the original physical signals, the embodiments of the present invention can effectively solve the problems of phase distortion and DC bias in the magnetization process, thereby providing an accurate data basis for the subsequent feature extraction of instantaneous magnetization impedance.

[0050] S2: Calculate the instantaneous rate of change of magnetization impedance at each moment. The instantaneous rate of change of magnetization impedance is positively correlated with the time derivative of the ratio of output voltage to excitation current, and negatively correlated with the product of the set experimental frequency and the peak value of the target magnetic flux density corresponding to the power amplifier.

[0051] It should be noted that this step aims to capture the physical dynamics of magnetic domain reversal within the material through mathematical modeling. Magnetic materials are nonlinear loads, and their equivalent impedance evolves in real time with changes in magnetization. In the small-signal region during the initial stage of magnetization, the material exhibits high impedance; however, as the magnetic field strength increases and the material approaches saturation, almost all of its internal magnetic domains have reversed, resulting in a significant decrease in magnetic induction and causing a momentary collapse in the excitation coil impedance. Without feature extraction of the instantaneous impedance change rate, the system will be unable to predict the arrival of this physical critical point.

[0052] Furthermore, in the small signal region, the signal-to-noise ratio is low under fixed gain, and the effective signal is easily drowned out by the background noise. In the saturation state, when the impedance suddenly decreases, if the gain remains constant, the output current will surge instantaneously, which will not only generate severe signal clipping and cause measurement data distortion, but also trigger the overcurrent protection of the power amplifier, thereby interrupting the magnetic characteristic measurement process.

[0053] Based on this, embodiments of the present invention can track impedance fluctuations by using the time derivative of the voltage-current ratio and normalize them in combination with experimental parameters, thereby achieving a leap from post-feedback to predictive regulation.

[0054] For example, in this embodiment of the invention, the method for obtaining the target magnetic flux density peak value corresponding to the power amplifier includes: obtaining the maximum output voltage and the maximum excitation current from the hardware limits of the power amplifier; obtaining the magnetic flux density corresponding to the maximum output voltage according to Faraday's law of electromagnetic induction, wherein the maximum output voltage is positively correlated with the magnetic flux density; obtaining the magnetic flux density corresponding to the maximum excitation current according to Ampere's theorem, wherein the maximum excitation current is positively correlated with the magnetic flux density; and taking the minimum value between the magnetic flux density corresponding to the maximum output voltage and the magnetic flux density corresponding to the maximum excitation current as the target magnetic flux density peak value corresponding to the power amplifier.

[0055] Specifically, impedance fluctuations can be tracked by the voltage-to-current ratio, thereby identifying the slope of impedance decrease. The greater the slope, the higher the risk of the material entering a saturation state.

[0056] For example, in an embodiment of the present invention, the instantaneous rate of change of magnetization impedance at each moment can be calculated using the following formula:

[0057] ;

[0058] For a moment The instantaneous rate of change of magnetization impedance, For a moment The induced voltage, For a moment The excitation current, To prevent constants with a denominator of zero, To set the experimental frequency, The target magnetic flux density peak value corresponding to the power amplifier. It is the absolute value symbol.

[0059] The experimental frequency can be set to 8kHz, and the specific setting can be adjusted according to actual needs.

[0060] The constant used to prevent the denominator from being zero is used to ensure computational stability. Optionally, in this embodiment of the invention, it can be set to... The specific settings can be configured according to actual needs.

[0061] In the above relation, This is the derivative term, used to reflect the slope of the instantaneous impedance change, assessing the degree of nonlinearity of the load entering the saturation region. The larger the slope, the closer the material is to saturation, and the higher the risk of saturation. When the rate of change of the ratio of induced voltage to excitation current (i.e., instantaneous impedance) with time increases, the rate of change of instantaneous magnetization impedance also increases.

[0062] This product is used for normalization. Since the impedance changes at different frequencies and magnetic flux densities are of different magnitudes, scaling is performed through this product, enabling the algorithm to adapt to different saturation points and different types of magnetic materials (such as nanocrystalline soft magnetic materials and silicon steel sheets), providing a unified saturation risk assessment scale for diverse measurement scenarios.

[0063] Based on the above steps, the instantaneous rate of change of magnetization impedance at each moment can be obtained. (See also...) Figure 2 As shown, Figure 2 This is a schematic diagram illustrating the instantaneous rate of change of magnetization impedance, provided as an embodiment of the present invention. The horizontal axis represents time in seconds, and the vertical axis represents the dimensionless rate of change of impedance.

[0064] As shown in the figure, the instantaneous magnetization impedance change rate exhibits periodic spike pulse characteristics within each excitation cycle. These spikes precisely correspond to the moments when the magnetic ring enters the magnetization transition region and the deep saturation region. This characteristic graph verifies the effectiveness of the instantaneous magnetization impedance change rate calculation method, proving that the system can monitor drastic fluctuations in load impedance in real time, providing a reliable physical basis for subsequent early warning and compensation.

[0065] Thus, by using the impedance change rate to predict the magnetization state, this embodiment of the invention can effectively assess the risk of the material entering the saturation region, thereby effectively preventing hardware overload damage caused by a sudden increase in current due to saturation and extending the service life of the experimental equipment.

[0066] S3: Calculate the dynamic load margin at each moment. The dynamic load margin is negatively correlated with the instantaneous rate of change of magnetization impedance and positively correlated with the difference between the power supply rail voltage and the output voltage amplitude of the power amplifier.

[0067] It should be noted that the power amplifier's supply rail voltage limits the maximum swing of the output voltage. Physically, if the amplitude of the induced voltage is already close to the supply rail voltage, the amplifier will lose the dynamic range to adjust further upwards. Without analyzing the load margin, the control algorithm may issue commands exceeding the hardware limits, causing the top of the output waveform to be clipped, resulting in clipping distortion or triggering overvoltage protection.

[0068] Based on this, embodiments of the present invention can quantitatively assess the safe operating space of equipment by constructing a load margin index, and use an exponential decay function to simulate the nonlinear degradation characteristics of electronic devices at the limit edge, thereby aligning the load demand with the hardware limits of the power amplifier in real time.

[0069] Furthermore, the power amplifier's supply rail voltage determines the maximum swing of the output voltage. If the power amplifier's output voltage approaches the maximum supply rail voltage, the amplifier will lose the dynamic space to further increase the voltage. If subsequent gain adjustment does not consider this constraint, it will inevitably lead to waveform clipping or overvoltage protection. When the magnetic material approaches saturation, the impedance will collapse instantaneously, causing the output voltage to change rapidly, resulting in a real-time change in the amplifier's actual load-bearing capacity. If the system's dynamic load-bearing capacity is not evaluated, the risk of instability under high magnetic flux cannot be identified, leading to frequent waveform oscillations or triggering of over-temperature protection during experiments. This invention, by combining hardware constraints and load requirements, can transform complex electromagnetic field changes into a safety line that the power amplifier can perceive.

[0070] For example, in an embodiment of the present invention, the dynamic load margin at each moment can be calculated using the following formula:

[0071] ;

[0072] For a moment Dynamic load-bearing capacity margin. This is the maximum power rail voltage of the power amplifier. For a moment The output voltage, For a moment The output voltage amplitude, The impedance fluctuation weighting coefficient is used. For a moment The instantaneous rate of change of magnetization impedance, For An exponential function with base 0.

[0073] The maximum power supply rail voltage of the power amplifier can be obtained from the equipment manual, for example, it can be set to 50V.

[0074] The impedance fluctuation weighting coefficient is used to control the system’s sensitivity to impedance fluctuations and to adjust the normalized dimensions, so that the exponent term is dimensionless data. The data value can be selected from 0.5 to 1.2, and can be set according to actual needs. This embodiment of the invention does not impose too many restrictions here.

[0075] In this relation, This reflects the static margin in the voltage dimension. The closer the output voltage is to the maximum supply rail voltage, the closer this fractional value is to 0, indicating a smaller physical space and a smaller dynamic margin.

[0076] This is an impedance risk correction term. Since the instantaneous rate of change of magnetization impedance reflects the severity of impedance collapse, the exponential term decreases extremely rapidly as the instantaneous rate of change of magnetization impedance increases, thus significantly compressing the calculated margin value. By directly incorporating the risk into the load margin calculation through the exponential term, the system can be extremely sensitive to danger signals in the high flux saturation region.

[0077] Based on the above steps, the dynamic carrying capacity margin at each time point can be obtained. (See also...) Figure 3 As shown, Figure 3 This is a schematic diagram illustrating the dynamic load-bearing capacity variation according to an embodiment of the present invention. The horizontal axis represents time in seconds, and the vertical axis represents the dynamic load-bearing capacity as a dimensionless value.

[0078] This graph reflects the real-time safety margin of the system during operation. As the output voltage amplitude increases and the risk of impedance collapse rises, the margin indicator shows a rapid downward trend. The dashed line in the graph represents the preset switching threshold. When the margin falls below this threshold, the system immediately activates the gain compression mechanism. This demonstrates the logical effectiveness of mapping load risk to hardware capacity.

[0079] Thus, by combining the output voltage amplitude and impedance change rate to calculate the dynamic carrying capacity margin, the embodiments of the present invention can establish a real-time mapping between the nonlinear magnetization requirements of magnetic materials and the hardware physical limits of the power amplifier, effectively transforming complex electromagnetic field changes into a safety line that the power amplifier can perceive, and providing a decision basis for the subsequent generation of gain scaling factors.

[0080] S4: Determine the gain scaling factor at each time point. The gain scaling factor is positively correlated with the dynamic load margin and its value ranges between the set upper and lower gain limits. The drive voltage command is adjusted in real time using the gain scaling factor to control the output gain of the power amplifier.

[0081] It should be noted that the dynamic load margin obtained based on the above steps can be used to assess the safe operating range of the power amplifier. Gain adjustment through dynamic load margin can balance the signal-to-noise ratio and system stability. Specifically, in the small-signal measurement region, a larger dynamic load margin requires the system to automatically increase the gain to optimize measurement accuracy and prevent weak signals from being drowned out by the noise floor; conversely, if the dynamic load margin is insufficient, the system must quickly and smoothly reduce the gain to prevent output overshoot. By employing nonlinear mapping, the possibility of sudden step noise can be reduced when switching between different order of magnitudes, thereby effectively reducing the interference of step noise on the observation of the fine magnetic structure of magnetic materials.

[0082] Based on this, embodiments of the present invention can determine the gain scaling factor through dynamic load margin.

[0083] For example, in an embodiment of the present invention, the gain scaling factor at each time step is determined by referring to the following relationship:

[0084] ;

[0085] For a moment The target gain scaling factor, This is the lower limit of the gain adjustment ratio. This is the upper limit of the gain adjustment ratio. The slope factor of the curve. This is the offset of the curve center. For a moment Dynamic load-bearing capacity margin. It is a natural constant.

[0086] The lower gain limit, upper gain limit, curve slope factor, and curve center offset were obtained through experimental calibration.

[0087] The upper gain limit can be set to 2.0, corresponding to a maximum gain range of 30 times; the lower gain limit can be set to 0.5; the specific settings can be made according to actual needs.

[0088] In this formula, the curve center offset is the dynamic load margin threshold, which sets the logical center for switching. Its value range can be set from 0.3 to 0.5, and in this embodiment, it is optionally set to 0.4. The specific value can be set according to actual needs. When the dynamic load margin is large and exceeds the threshold, the function value tends towards 1, causing the target gain scaling factor to approach the upper gain limit, thereby improving signal strength. When the dynamic load margin decreases to below the threshold, the function value drops rapidly, causing the target gain scaling factor to approach the lower gain limit, thereby achieving rapid gain compression to protect the hardware.

[0089] The curve slope factor determines the switching sensitivity and can be set between 10 and 30.

[0090] Based on the above steps, the target gain scaling factor for each time moment is obtained, and the driving voltage command can be adjusted based on the target gain scaling factor.

[0091] For example, in an embodiment of the present invention, the real-time adjustment of the drive voltage command using a gain scaling factor includes: using the product of the current gain scaling factor and the drive voltage command as the final execution command value at the current moment.

[0092] For example, in an embodiment of the present invention, controlling the output gain of the power amplifier includes: mapping the final executed instruction value to a programmable instruction and injecting it into the register of the power amplifier in real time, and adjusting the output level through a numerically controlled gain circuit.

[0093] Specifically, the final execution instruction value can be mapped to a programmable instruction (such as via the 'ATA,SET,AMP,[Value]' instruction). For example, when the calculated gain scaling factor is 21.5, the system issues (ATA,SET,AMP,0215). This is injected into the device register in real time via the USB programmable interface, causing the internal numerically controlled gain circuit to adjust the output level.

[0094] Thus, by generating and executing the adaptive gain scaling factor nonlinearly in real time, the embodiments of the present invention can effectively solve the gain mismatch problem in a wide dynamic range, and greatly improve the working stability of the power amplifier under magnetic load saturation while ensuring measurement accuracy.

[0095] See also Figure 4 and Figure 5 As shown, Figure 4 This diagram illustrates a comparison of dynamic gain and fixed gain control effects according to an embodiment of the present invention. The diagram details the output performance of the traditional fixed gain mode and the dynamic gain mode of the present invention, with the horizontal axis representing time in seconds and the vertical axis representing output voltage in volts. It can be seen that, using the solution of the present invention, the output waveform is significantly superior in amplitude to the fixed gain mode, and its peak value is precisely locked within the power amplifier voltage limit, without clipping distortion. This directly reflects the significant advantage of this solution in balancing small-signal accuracy and large-signal stability.

[0096] Figure 5This diagram illustrates a comprehensive analysis of hysteresis loop and control effect provided by an embodiment of the present invention. The horizontal axis represents magnetic field strength in amperes per meter, and the vertical axis represents magnetic flux density in tesla. This comprehensive diagram demonstrates that under adaptive gain control, the system can obtain an extremely smooth and symmetrical saturated hysteresis loop. This proves that the present invention significantly improves the consistency and reliability of nonlinear magnetic load measurements through adaptive optimization allocation of the power amplifier's output capability.

[0097] This invention also discloses a power amplifier gain control system for magnetic characteristic measurement, including a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement a power amplifier gain control method for magnetic characteristic measurement provided by this invention.

[0098] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

[0099] In this invention, the aforementioned memory can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0100] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A power amplifier gain control method for magnetic characteristic measurement, characterized in that, include: Obtain the output voltage and magnetizing current of the power amplifier; Calculate the instantaneous rate of change of magnetization impedance at each moment, including: , For a moment The instantaneous rate of change of magnetization impedance, For a moment The output voltage, For a moment The excitation current, To prevent constants with a denominator of zero, To set the experimental frequency, The target magnetic flux density peak value corresponding to the power amplifier. It is the absolute value symbol; Calculate the dynamic load margin at each time point, including: , For a moment Dynamic load-bearing capacity margin. This is the maximum power rail voltage of the power amplifier. For a moment The output voltage amplitude, For impedance fluctuation weighting coefficients, For An exponential function with base 0; Determine the gain scaling factor at each time step, including: , For a moment The target gain scaling factor, , These are the lower and upper limits of the gain adjustment ratio, respectively. The slope factor of the curve. This is the offset of the curve center. The gain lower limit, gain upper limit, curve slope factor, and curve center offset are obtained through experimental calibration. The output gain of the power amplifier is controlled by adjusting the drive voltage command in real time using a gain scaling factor.

2. The power amplifier gain control method for magnetic characteristic measurement according to claim 1, characterized in that, The acquisition of the power amplifier's output voltage and excitation current includes: The sampling circuit and the signal generator are synchronized in hardware to ensure the phase consistency between the excitation current signal and the induced voltage signal, so as to obtain the output voltage and excitation current of the power amplifier at each moment.

3. The power amplifier gain control method for magnetic characteristic measurement according to claim 2, characterized in that, The process of obtaining the output voltage and excitation current of the power amplifier also includes: An isolation transformer with a turns ratio of 1:1 is connected between the power amplifier and the excitation coil to suppress the DC bias component.

4. The power amplifier gain control method for magnetic characteristic measurement according to claim 1, characterized in that, The method for obtaining the target magnetic flux density peak value corresponding to the power amplifier includes: By taking advantage of the hardware limits of the power amplifier, the maximum output voltage and maximum magnetizing current are obtained. The magnetic flux density corresponding to the maximum output voltage is obtained according to Faraday's law of electromagnetic induction, and the maximum output voltage is positively correlated with the magnetic flux density. The magnetic flux density corresponding to the maximum excitation current is obtained according to Ampere's theorem, and the maximum excitation current is positively correlated with the magnetic flux density. The minimum value between the magnetic flux density corresponding to the maximum output voltage and the magnetic flux density corresponding to the maximum excitation current is taken as the target peak magnetic flux density of the power amplifier.

5. The power amplifier gain control method for magnetic characteristic measurement according to claim 1, characterized in that, The real-time adjustment of the drive voltage command using a gain scaling factor includes: The product of the current gain scaling factor and the drive voltage command is used as the final execution command value at the current moment.

6. The power amplifier gain control method for magnetic characteristic measurement according to claim 5, characterized in that, The control of the output gain of the power amplifier includes: The final execution instruction value is mapped to a programmable instruction and injected into the register of the power amplifier in real time, and the output level is adjusted by a numerically controlled gain circuit.

7. A power amplifier gain control system for measuring magnetic characteristics, characterized in that, include: A processor and a memory, the memory storing computer program instructions that, when executed by the processor, implement a power amplifier gain control method for magnetic characteristic measurement according to any one of claims 1-6.

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