US 11,656,200 B2
Electromagnetic non-destructive quality testing method, and testing circuit and system therefor
Zhouyi Hu, Wuxi (CN)
Assigned to Jiangyin Tianrun Information Technology Co., Ltd, Wuxi (CN)
Filed by Jiangyin Tianrun Information Technology Co., Ltd, Wuxi (CN)
Filed on Nov. 14, 2022, as Appl. No. 18/55,394.
Application 18/055,394 is a continuation of application No. PCT/CN2020/101933, filed on Jul. 14, 2020.
Prior Publication US 2023/0076262 A1, Mar. 9, 2023
Int. Cl. G01N 27/83 (2006.01); G01N 27/04 (2006.01); G01R 27/26 (2006.01); G01R 29/08 (2006.01)
CPC G01N 27/83 (2013.01) [G01N 27/045 (2013.01); G01R 27/2611 (2013.01); G01R 29/08 (2013.01)] 11 Claims
OG exemplary drawing
 
1. An electromagnetic non-destructive quality testing method, comprising the following steps:
S1, with a first-order resistor-inductor (RL) circuit as a magnetizing circuit for a magnetizing coil and the magnetizing coil as an inductor of the first-order RL circuit, allowing, by an electronic automatic control switch according to preset maximum current Imax and minimum current Imin of the magnetizing coil, the first-order RL circuit to alternate a direct-current excitation response and a zero-input response,
wherein a direct current flowing through the magnetizing circuit increases regularly during the direct-current excitation response, and the current of the magnetizing circuit decreases regularly during the zero-input response;
S2, under the direct-current excitation response and the zero-input response of the first-order RL circuit, generating, by the magnetizing coil having the direct current changing alternately in magnitude flowing therethrough, a direct-current magnetic field changing alternately in magnetic field intensity;
S3, placing a testing object having electromagnetic susceptibility in the direct-current magnetic field changing alternately in magnetic field intensity in step S2 so that the testing object is magnetized by the magnetic field changing alternately in magnetic field intensity while causing a change in magnetic induction intensity or magnetic flux of the magnetizing coil, thereby leading to a change in inductance of the magnetizing coil, wherein when a differential change of the testing object is detected, a change in magnetic induction intensity or magnetic flux is caused, resulting in that the inductance of the magnetizing coil changes with the differential change of the testing object; and
S4, detecting the differential change of the testing object by detecting the inductance of the magnetizing coil in the RL circuit, thereby determining whether a quality defect occurs, or analyzing electromagnetic properties of the testing object by detecting the inductance change of the magnetizing coil or detecting electrical characteristic change caused by the inductance change of the magnetizing coil, thereby analyzing related properties of the testing object.
 
7. A testing circuit for electromagnetic non-destructive quality testing, comprising a direct-current voltage-stabilized power source for connection with power supply, a first-order RL circuit composed of a magnetizing coil and a current-limiting resistor, and a circuit comprising an electronic exciting current switch, wherein the magnetizing coil is connected to a freewheeling circuit and configured to freewheel when the electronic exciting current switch is turned off;
the electronic exciting current switch is configured to connect or disconnect the first-order RL circuit composed of the magnetizing coil and the current-limiting resistor with or from the direct-current voltage-stabilized power source, bringing the first-order RL circuit into or out of a direct-current excitation response state;
when the electronic exciting current switch is turned on, a magnetizing current flows into the magnetizing coil from a positive pole of the direct-current voltage-stabilized power source through the current-limiting resistor, and then to a negative pole of the direct-current voltage-stabilized power source through the electronic exciting current switch;
the first-order RL circuit is brought into the direct-current excitation response state, and when the magnetizing current of the magnetizing coil reaches a set maximum current Imax, the electronic exciting current switch is turned off; and
when the electronic exciting current switch is turned off, the freewheeling circuit provides a continuous current passage for the magnetizing coil, and the first-order RL circuit is brought into a zero-input response state with the magnetizing current decreasing exponentially; when the magnetizing current reaches a set minimum current Imin, the electronic exciting current switch is turned on again; and a direct-current excitation response and a zero-input response of the magnetizing coil are thus alternated cyclically.
 
9. A testing system using an electromagnetic non-destructive quality testing method, comprising a testing circuit that comprises a circuit formed by connecting a first-order RL circuit composed of a magnetizing coil and a current-limiting resistor to a direct-current voltage-stabilized power source and an electronic exciting current switch, with the magnetizing coil being connected to a freewheeling circuit;
the electronic exciting current switch is configured to control a circuit formed by the first-order RL circuit composed of the magnetizing coil and the current-limiting resistor, and the direct-current voltage-stabilized power source;
when the electronic exciting current switch is turned on, a magnetizing current flows into the magnetizing coil from a positive pole of the direct-current voltage-stabilized power source through the current-limiting resistor, and then to a negative pole of the direct-current voltage-stabilized power source through the electronic exciting current switch, inducing a direct-current excitation response of the magnetizing coil; when the magnetizing current of the magnetizing coil reaches a set maximum current Imax, the electronic exciting current switch is turned off;
when the electronic exciting current switch is turned off, the freewheeling circuit provides a continuous current passage for the magnetizing coil, inducing a zero-input response of the magnetizing coil with the magnetizing current decreasing exponentially; when the magnetizing current of the magnetizing coil reaches a set minimum current Imin, the electronic exciting current switch is turned on again; and the direct-current excitation response and the zero-input response of the magnetizing coil are thus alternated cyclically;
a testing object having electromagnetic susceptibility is placed in a direct-current magnetic field changing alternately in magnetic field intensity so that the testing object is magnetized by the magnetic field changing alternately in magnetic field intensity while causing a change in magnetic induction intensity or magnetic flux of the magnetizing coil, thereby leading to a change in inductance of the magnetizing coil; when a differential change of the testing object is detected, a change in magnetic induction intensity or magnetic flux is caused, resulting in that the inductance of the magnetizing coil changes with the differential change of the testing object; and
the differential change of the testing object is detected by detecting the inductance of the magnetizing coil in the RL circuit, thereby determining whether a quality defect occurs; or electromagnetic properties of the testing object are analyzed by detecting the inductance of the magnetizing coil, thereby analyzing related properties of the testing object.