Patent ID: 11894696
Assignee: UNIVERSITAT STUTTGART
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  B  Y | IPC B  H

Claim 0:
1. Method for detecting electrically conductive foreign bodies during inductive energy transmission between a primary coil (1) and a secondary coil (2), in particular during inductive charging processes, in which method at least one sensor coil (5) is arranged between the primary coil (1) and the secondary coil (2), and in which a current induced in the sensor coil (5) during the energy transmission is detected and evaluated,
characterized in that the sensor coil (5) is connected to at least one capacitor (C3s) to form a closed resonant circuit which is matched to an excitation frequency of the primary coil (1) and in that the phase position of the current in the closed resonant circuit in relation to a reference signal is used to determine whether one or multiple electrically conductive foreign bodies (4) are present between the primary coil (1) and the secondary coil (2);
wherein the reference signal is a voltage at the primary coil (1), or—in case of an excitation of the primary coil (1) based on a PWM signal—the reference signal is the PWM signal.