Counter-Interfaced Digital Control of Self-Sensing Magnetic Suspension Systems with Hysteresis Amplifiers

A low-cost digital control system is developed for self-sensing magnetic suspension using hysteresis amplifiers.A unipolar-type hysteresis amplifer is designed and manufactured for experimental study.Since the switching rate of the hysteresis amplifier is sensitive to the load impedance, the gap between the electromagnet and the suspended object is estimated from the switching signal.In the developed system, the frequency of the switching signal of the amplifier is converted to a digital form by counting by a counter circuit.The converted signal is inputted to a computer calculating control input for stabilization.The developed digitally controlled magnetic suspension system succeeds in actual self-sensing operation.