Self-Sensing Control of Electrostatic Suspension Using Variable Capacitor

Abstract

Voltage control using a variable capacitor and floator position estimation are proposed for designing a low-cost electrostatic suspension control system. When an electrostatic actuator and a variable capacitor are connected in series to a constant power supply, the voltage applied to the suspension system can be changed by varying the capacitance of the variable capacitor because the electrostatic suspension system can be treated as a capacitor. Moreover, the voltage is determined by these capacitances and so the floator position can be estimated from the voltage applied to the suspension system and the capacitance of the variable capacitor. The proposed voltage control system enables electrostatic suspension without a high-voltage amplifier or direct floator position detection. Therefore, this control system can reduce the total cost of electrostatic suspension systems. The principle of the proposed self-sensing control is described using a basic electrostatic suspension model. The position of the floator was estimated according to this principle. Self-sensing suspension was achieved by feeding back the estimated signal.