Fundamental and experimental research on a switch-driven eddy-current displacement sensor

The fundamental of a switch-driven eddy-current displacement sensor is analyzed based on the eddy current power loss. The sensor achieves target displacement detection based on the relationship between the gas gap and the working current; and only one low pass filtering is needed for the signal conditioning. A series of experiments were carried out at different switching frequencies with iron, aluminum and nonmagnetic stainless steel as the targets; and the experiment data were analyzed. Analysis results show that as the switching frequency changes the detection sensitivity experiences a similar variation process for different targets; and the sensitivity reaches a negative maximal value around the resonance frequency, the sensitivity reaches two positive maximal values at approximately half and 1.5 times the resonance frequency; the sensitivity for iron has its largest value around the resonance frequency, and the sensitivity for aluminum takes the second place.