Impulse electromagnet for electromagnetic acoustic transducer

Abstract

The invention belongs to the field of electromagnetic ultrasonic nondestructive inspection and discloses an impulse electromagnet for an electromagnetic acoustic transducer, which is capable of improving the performance of the EMAT and reducing the volume and power consumption of the probe of the EMAT. The invention aims to solve various problems aroused by a magnet in the traditional electromagnetic acoustic transducer and reduce probe volume. The impulse electromagnet for the electromagnetic acoustic transducer consists of an impulse electromagnet and an impulse electromagnet driving circuit, wherein the impulse electromagnet consists of a framework and a coil; and the impulse electromagnet driving circuit consists of a power pulse forming circuit, a power driving circuit, a control main machine and a booster circuit. The impulse electromagnet for the electromagnetic acoustic transducer can build a strong magnetic field in a very short period before the EMAT starts to operate to meet the working needs of the EMAT; and after the EMAT stops operating, the magnetic field disappears quickly. The impulse electromagnet is short in operation time, small in power consumption and small in volume and can be used in on-line detection of low-power consumption and portable ferromagnetic test pieces, and the like.

Description

(1) Technical field [0001] The invention relates to electromagnetic ultrasonic detection technology, in particular to a pulsed electromagnet used for electromagnetic ultrasonic transducers. (2) Background technology [0002] Electromagnetic acoustic transducer (EMAT for short) is a new type of ultrasonic transmitting and receiving device. Compared with the traditional piezoelectric ultrasonic transducer, it has the advantages of no acoustic coupling agent and no pretreatment on the surface of the specimen, and has broad application prospects. [0003] EMAT usually consists of three parts: transmitting and receiving coils, strong magnetic field and test pieces. A strong magnetic field is a necessary condition for EMAT to work properly. There are many ways to generate a strong magnetic field, such as permanent magnets, DC electromagnets and power frequency AC electromagnets. Although these magnetic field generation methods can effectively provide the strong magnetic field r...

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Problems solved by technology

Although these magnetic field generation methods can effectively provide the strong magnetic field required for EMAT work, they make the probe bulky, heavy and inconvenient to carry, and there are still many shortcomings: the permanent magnet magnetic field is strong and constant, and in practical applications At the same time, the constant magnetic field is easy to make the probe absorb a large amount of iron filings, which is difficult to clean; when the temperature rises to the Curie point of the ferromagnetic material, the ferromagnetic material becomes paramagnetic, and the permanent magnet and The magnetism of the electromagnet core disappears, so that the static magnetic field required for the transducer to work is significantly weakened, and the energy conversion efficiency is significantly reduced; although DC and power frequency AC electromagnets can turn off the power supply when not in use, such electromagnets are designed Generally, dynamic parameters are not considered, and the magnetic field takes a long time to establish and end. When the frequency of repeated work of the transducer is high, the electromagnet cannot be effectively switched on and off. Generally, the electromagnet needs to be kept energized during the repeated work of the transducer.

[0006] The application of pulsed electromagnets in the field of electromagnetic ultrasound has not yet been reported

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