Self-sensing magnetic suspension using hysteresis amplifiers

A self-sensing suspension system was studied, both theoretically and experimentally. It used a switching amplifier whose switching times were controlled by a current comparator with some hysteresis. It was shown that the switching frequency of the amplifier changed linearly with the gap between the electromagnet and the suspended object. Phase-locked loop (PLL) and frequency-feedback (FFB) control were applied to stabilize the suspension system. Frequency-to-voltage (F/V) converters were used to realize FFB control. Feeding back the F/V converted signal led to stable suspension. When a PLL control was activated in addition to the FFB control, the accuracy of Boating was improved. (C) 1998 Elsevier Science Ltd. All rights reserved.