The principle of a metal detector is quite simple and as the name suggest it is a device that can identify if metals are present say in hard to find places like under the soil, inside rocks etc. It finds its use in detecting things from land mines (really a wonderful use of metal detector which has saved many thousands of life and is still continuing to save) to gold mines.
+ Q8 x# p. m) ^' s% |/ e9 M) J金属探测器的原理$ K: s4 b' w! K* B% B0 u! Z
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Most metal detector have 2 coils – one coil carries alternating current usually at very high frequency (1-10 KHz) and other coil acts like a receiver. The excited coil generates a magnetic field and this induces a small amount of current in the receiver coil. This current (also called as Induced current or Eddy current) is known and calibrated. Now when you take this arrangement near a metallic (or ferromagnetic) substance, two things happen. First, the excited coil also induces an eddy current in the metallic (or ferromagnetic) substance. This eddy current produces its own magnetic field that opposes the magnetic field produced by the coils. This causes the eddy current in the receiver coil to drop. A sensor senses this drop in eddy current from the expected value and gives a signal indicating the presence of a metallic substance.
0 _( |8 ^5 M1 t金属探测器上俩线圈的意义。
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In the figure below, the orange coil is the excited coil and the green one is the receiver coil. High frequency AC current is circulated in the orange coil and the eddy currents induced in the green coil in the absence of any metallic substance is calibrated.; W* W3 W r% b) S' L1 s
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8 O; L9 L6 ] q7 N8 f对于工程师而言,如何让solidworks和emsworks插件在设计金属探测器的电磁仿真时能发挥重要作用,要考虑以下几点:
% o1 y) m7 E4 x7 m! gWhat is the right size of the coil?
6 T& G7 a4 o1 z( T1 TWhat frequency and magnitude of AC current should be applied? ( a- _: A4 d" ? Y: e3 H9 X% E( x$ g
What is the induced current in the receiver coil under ideal (no metal in the vicinity) conditions?
3 M1 U+ R& _* |- I7 n6 d6 mHow can I package the entire arrangement into a product?
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emsworks可以仿真出线圈的磁感应强度及其它/ N6 p9 c7 n l1 n1 ~
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