How to detect the high frequency transformer core?

Measurement of dc magnetic characteristics

Tributary parameters of soft magnetic materials have different testing requirements according to different materials.For electrical pure iron and silicon steel, there are mainly the measurement of amplitude magnetic induction intensity Bm under standard magnetic field intensity, such as B5, B10, B20, B50, B100, etc., as well as the maximum permeability m and coercivity Hc, etc..For permalloy and amorphous, initial permeability I, maximum permeability m, Bs and Br;The same is true for soft ferrite materials;Mu I, mu m, Bs and Br, etc.Obviously, as long as we manage to measure the magnetic properties of the material under closed conditions, we can control the use of the material very well (part of the material is measured using the open circuit method).The most common methods:

1. Impact method: solenoids can be used for silicon steel with Epstein square ring, pure iron bar, weak magnetic material and amorphous strip, and other samples that can be processed into closed magnetic ring can be tested.The test sample requires strict demagnetization to a neutral state.Each test point was recorded with a commutating dc power supply and a shock galvanometer. The corresponding magnetic characteristic parameters were obtained by calculating and describing Bi and Hi on the coordinate paper. They were widely used before the 1990s.The test method of this kind of instrument is classical, the test can be stable *, the price of the instrument is relatively cheap, and it is easy to maintain.Disadvantages are: the requirements for testing personnel is quite high, need to carry out point-by-point testing work is quite heavy, slow, pulse non-instantaneous time error is difficult to overcome.

2. Coercimeter method: it is a measurement method specially designed for the pure iron bar, only measuring the Hcj parameter of the material.The test market first saturates the sample with magnetization, and then reverses the magnetic field.Under a certain magnetic field, the throwing coil or sample is pulled away from the solenoid, so that the external impact galvanometer has no deflection, and the corresponding reverse magnetic field is the Hcj of the sample. This measurement method can measure the Hcj of the material well, with small investment in equipment, practical and no requirement for the shape of the material.

3. Dc hysteresis loop meter: its testing principle is the same as that of the hysteresis loop of permanent magnetic materials.It is mainly in the integrator under the need for greater efforts, there are photoelectric amplification transformer integration, resistance and capacity integration, v-f conversion integration and electronic sampling integration and other forms.Domestic equipment: CL1, cl6-1, CL13;The foreign equipment includes yokogawa 3257 and LDJ AMH401, etc., the level of integrator in foreign countries is much higher than that in China, and the control precision of b-speed feedback is also very high.This method has the advantages of fast test speed, intuitive result and convenient use.Disadvantages are the I and m test data are inaccurate, generally more than 20%.

4. Simulated impact test: it is the best test method to test soft magnetic dc characteristics at present. It is actually a computer simulation method of artificial impact.This method was developed by the Chinese academy of metrology and loudi institute of electronics in 1990.Products include: MATS-2000 magnetic material measuring device (stop production), nim-2000d magnetic material measuring device (metrology institute) and TYU-2000D soft magnetic dc automatic measuring device (tianyu electronics).This measurement method avoids the interference of the circuit to the measurement circuit, effectively inhibits the zero drift of the integrator, and also has the function of scanning test.

Measurement method for ac characteristics of soft magnetic materials

The measuring methods of ac hysteresis loop include oscilloscope method, ferrometer method, sampling method, transient waveform storage method and computer controlled ac magnetization characteristic testing method.At present, the main methods of measuring ac hysteresis loop in China are oscilloscope method and computer controlled ac magnetization test method.The main enterprises adopting the wave instrument method are: dajie ande, yanqin nanometer and zhuhai grun, etc.Computer controlled ac magnetization testing methods are mainly used by the Chinese academy of metrology and tianyu electronics.

1, oscilloscope method: test frequency 20hz-1mhz, wide working frequency, simple equipment, easy to operate.But the test accuracy is low.The test method is to connect the non-inductive resistance sampling primary current to the X channel of the oscilloscope, and connect the Y channel to the secondary voltage signal after adopting RC integral or miller integral, so that the BH curve can be directly observed from the oscilloscope.This method is suitable for the comparison measurement of the same kind of material, and the test speed is fast, but it cannot accurately measure the magnetic characteristic parameters of the material.In addition, due to the lack of closed-loop control of integral constant and saturation magnetic inductance, the corresponding parameters of BH curve cannot represent the real data of the material, which can be used for comparison.

2. Ferromagnetic instrument method: ferromagnetic instrument method is also called vector meter method, such as domestic CL2 type measuring instrument.The measurement frequency is 45hz-1000hz.The equipment is simple in structure and easy to operate, but only the normal test curve can be recorded.The design principle USES phase-sensitive rectification to measure the instantaneous value of voltage or current, as well as the phase of both. The BH curve of the material is plotted by the recorder.Bt=Uwhere M is mutual inductance.

3. Sampling method: the sampling method USES the sampling conversion circuit to convert the high-speed changing voltage signal into the voltage signal with the same waveform but slow changing speed, and USES the low-speed AD for sampling.The test data is accurate, but the test frequency is up to 20kHz, which is difficult to adapt to the high frequency measurement of magnetic materials.

4, the use of computer control of the ac magnetic characteristics of the test method: this method is the full use of computer control and software processing capacity of the measurement method, but also the future development of a living direction of the product.The design USES a computer with a sampling loop for closed-loop control so that the entire measurement can be arbitrary.Once the measuring conditions are input, the measuring process is completed automatically and the control can be achieved automatically.The measurement function is also very powerful, almost all parameters of soft magnetic materials can be accurately measured.   

At the same time, the ps-b curve, ps-f curve and magnetization curve of materials can be measured automatically, providing detailed parameters and guidance for subsequent design.At present, the only instrument that can measure continuous frequency up to 500kHz with this method is lianzhongji technology. Other enterprises use point frequency measurement, so it is not so convenient to test.In terms of the accuracy of the products, as the domestic calibration agencies in this regard are not too perfect, it is generally necessary to use the equipment of iwasaki for comparison, and the power consumption can be compared with the 2335 of the United States.

For more information,please contact us at sales@xfullstar.com