C-type sensor for DC magnetic bias dynamic magnetic-flux measurement and detection method thereof

Abstract

The invention relates to a C-type sensor for DC magnetic bias dynamic magnetic-flux measurement and a detection method thereof. The C-type sensor includes a C-type auxiliary core, an auxiliary coil, a high frequency AC drive circuit, a current transformer and an output circuit. The C-type auxiliary core includes a core main body and extending parts which are arranged at two ends of the core main body and extend towards the same side. The auxiliary coil is wound on the core main body. The high frequency AC drive circuit includes a MOSFET bridge inversion circuit which is used for converting DC power sources to high frequency AC so as to drive the auxiliary coil. The current transformer is used for detecting loop currents in the auxiliary coil. The output circuit is connected with the current transformer and used for processing and outputting the currents detected by the current transformer. The C-type sensor does not need samples, shares one part of the magnetic circuit with the main core of to-be-tested electromagnetic equipment through the auxiliary core of the sensor, can cause change of inductance of windings on the auxiliary core according to change of magnetic reluctance in the magnetic circuit, and can timely acquire magnetic flow dynamic change waveforms of the main core on line by measuring the inductance value of the winding on the auxiliary core.

Description

technical field [0001] The invention relates to the measurement of magnetic flux of electrical equipment, in particular to a C-type sensor for DC bias dynamic magnetic flux measurement and a detection method thereof, belonging to the field of electrical equipment detection. Background technique [0002] DC bias is an abnormal working state during the operation of electromagnetic equipment. It exists widely in the electromagnetic field. For example, the magnetically controlled saturable reactor achieves the purpose of controlling the inductance by controlling the DC bias in the iron core. Furthermore, with the rapid rise of power electronics technology, rectification and inverter circuits are widely used to bring a certain DC component to the transformer winding, especially at high frequencies, which seriously affects the power quality. In addition, my country's long-distance and large-capacity UHV AC-DC power grids are relatively concentrated, resulting in an increase in gro...

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Problems solved by technology

[0004] 1. The Epstein square circle method and the ring sample method are traditional measurement methods. The measurement of the magnetic induction intensity is obtained by the law of electromagnetic induction, and the measurement of the magnetic field intensity is obtained according to the Ampere loop law. Loop law magnetic path length is difficult to determine accurately

[0005] 2. It is very difficult to make samples of the Epstein square method and the ring sample method

The samples required by the Epstein square method must be made in strict accordance with the specified size, and the minimum quantity and quality of samples are also limited.

However, the sample piece of the ring sample method must be made into a ring shape, which is difficult to achieve

[0006] 3. The single-chip measurement method is a new method proposed by Japanese scholar Takaaki Yamayoto, etc., but it is only suitable for the measurement of the magnetization characteristics of ferromagnetic materials under DC or AC excitation.

[0007] Later, some scholars proposed online measurement based on vibration. However, the vibration characteristics of the equipment under test under DC bias are closely related to factors such as DC bias, excitation characteristics of the iron core, and load current. Field testing is affected by many factors, making it difficult to be accurate and clear. reflect the magnetic flux characteristics under DC bias

[0008] To sum up, the traditional methods need to manufacture a variety of samples, resulting in a lot of waste of materials, and more importantly, they can only guarantee the data measured off-line, and the actual operation usually contains two kinds of signals, AC and DC. Although domestic and foreign scholars combined a series of mathematical methods to extrapolate the synthetic data on this basis, there is still a certain gap between the real and accurate values.

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