Apparatus for the electromagnetic control of the suspension of an object

摘要

An apparatus for the electromagnetic control of the suspension of an object including an electromagnet including an inductive coil, a source of electric power for the electromagnet which source includes a controllable electric supply device capable of delivering a controlled electric supply to the coil of the electromagnet, a control signal producer for producing an error control signal in response to an incremental change in a parameter related to the position of the object relative to the electromagnet and a negative feedback control loop for feeding an error control signal generated by the control signal producer to the electrical supply device to adjust the electrical supply to the coil so as to stabilise the suspension of the object relative to the electromagnet, wherein the control signal producer includes a detector for detecting the component VL of voltage across the coil which is due to pure inductance L of the coil, a detector for detecting the current i flowing through the coil, a device for deriving from the detected value of VL and the detected value of i opposing signals and a balances for balancing the opposing signals whereby an error control signal generated by the control signal producer represents a deviation from the perfect balance of the opposing signals and causes a correction signal to be applied by the electrical supply to restore the balance.