Self-Sensing Waveform Control for a Low-Frequency Electromagnetic Vibrator

In this paper, a self-sensing model of an electromagnetic vibrator is analyzed to pick up linear velocity directly without any extra sensors. A feedback control system is then established based on the self-sensed velocity. As a result, the bandwidth of the constant-velocity segment of the vibrator can be expanded and the total harmonic distortion (THD) of the output waveform is decreased in the low-frequency range. The influence of different parameters in the feedback control system on the THDs is experimentally analyzed. Comparing with the conventional feedback control system with an extra displacement sensor, the proposed control system is more powerful in reducing the THDs of acceleration waveform to be lower than 1% at the frequencies from 0.1 to 10 Hz, but without any other feedback sensors.