Application Cases

Experiment Name: Application of Power Amplifiers in High-Frequency Magnetic Property Measurement of Nanocrystalline Soft Magnetic Materials (Losses, Hysteresis Loops, Magnetostriction)

Experimental Content:
Using an amplifier to adjust and amplify the amplitude of voltage waveforms such as sine waves, triangular waves, symmetrical square waves, and asymmetrical square waves generated by a signal generator, the magnetic flux density inside the nanocrystalline magnetic ring is driven to the expected amplitude. The vibration and magnetization characteristics of the nanocrystalline magnetic ring are measured under varying magnetic flux densities, excitation frequencies, and excitation waveforms.

Research Direction: Magnetic properties of magnetic materials and measurement techniques

Testing Equipment:
AFG1062 signal generator, ATA-3040 power amplifier, TPP0201 voltage probe, TBS1152B oscilloscope, SRS6050 high-frequency current probe, 1A2100 acceleration sensor

Experimental Procedure:
The excitation signal is generated by the signal generator, and waveforms of different shapes can be compiled using ArbExpress software. The signal is then amplified by the power amplifier (ATA-3040) and connected to a transformer with a turns ratio of 1:1. The transformer is used here to filter out any DC component, preventing DC bias from affecting the measurement results. The secondary side of the transformer is connected to the magnetic ring under test, and its induced voltage is captured by an oscilloscope, while the excitation current is measured using a high-frequency current probe. The data for $i_1(t)$ and $u_2(t)$ are recorded, and after conversion, the magnetic field strength $H(t)$ and magnetic flux density $B(t)$ are obtained.

The vibration characteristics of the magnetic ring are measured using a 1A2100 acceleration sensor attached to its surface, with a sensitivity of 100 mV/g and a measurement range of ±50g. Since the vibration signal obtained from the experiment cannot be read directly, it needs to be converted into a voltage signal by a conditioner and displayed on the oscilloscope. Therefore, the final vibration acceleration magnitude is the voltage value displayed on the oscilloscope divided by the sensitivity.

Experimental Results:

1. Under symmetrical square wave excitation, the hysteresis loop exhibits symmetry. As the duty cycle increases, the area of the hysteresis loop gradually decreases, leading to a reduction in losses. Under asymmetrical square wave excitation, when the duty cycle is 0.6 or 0.8, the hysteresis loop exhibits a superimposed positive DC magnetic field; when the duty cycle is 0.2 or 0.4, a superimposed negative DC magnetic field is observed.

2. At the same magnetic flux density and different frequencies, the vibration acceleration under triangular wave excitation is greater than that under sine wave excitation but remains smaller than under symmetrical and asymmetrical square wave excitation. Under symmetrical square wave excitation, the vibration acceleration of the magnetic ring decreases as the duty cycle increases, reaching a maximum at a duty cycle of 0.2 and a minimum at a duty cycle of 1.0. The vibration amplitude is relatively larger at frequencies of 4000 Hz, 6000 Hz, and 8000 Hz. Under asymmetrical square wave excitation, the vibration acceleration at duty cycles of 0.2 and 0.8 is similar and greater than that at duty cycles of 0.4 and 0.6. The vibration acceleration is highest at frequencies of 6000 Hz and 8000 Hz.

   
   

3. Fast Fourier Transform (FFT) was performed on excitation voltages at 2000 Hz and 6000 Hz for sine waves, triangular waves, symmetrical square waves, and asymmetrical square waves (duty cycle 0.8) to obtain frequency spectra. The voltage spectra indicate that sine and triangular wave voltage signals are dominated by the fundamental frequency. In contrast, square wave voltages contain numerous high-frequency harmonic excitations in addition to the fundamental frequency, with asymmetrical square waves exhibiting even more high-frequency harmonic components. As a result of these high-frequency harmonic excitations, the vibration of the magnetic ring is more complex under symmetrical and asymmetrical square wave voltage excitation.

   
   

Role of Aigtek Power Amplifier in This Experiment:
Driving the nanocrystalline magnetic ring to generate the excitation signal

Figure: ATA-3040C Power Amplifier Specifications and Parameters