I helped my colleagues simulate inductance of vr crank sensor in Maxwell but my simulation result is quite different compared to the test one. Our sensor is quite simple, just a piece of permenant magnet, a piece of flux concentrator made of normal steel, and one copper coil hooked outside of the flux concentrator. It is that simple. My colleague used LCR meter to test the inductance and it was around 300mH. However, my result was around 400mH. It is LCR HiTESTER 3522-50: http://www.hioki.com/product/352250/index.html One thing I cannot understand is I do not know how LCR meter measures the inductance. What I learned at school is that inductance always varies with the current. With coil terminals connected to LCR meter, I do not know what current is there. The internal resistance of coil is 1000ohms. I do not have any test experience. Can you give me a hint? Also, my colleague told me if the sensor is covered with an AL case, the inductance goes lower, around 200mH. Do you know the reason? Many thanks.