Method and device for detecting a device in a wireless power transmission system

A transmitter for detecting a receiver via a capacitance change, the transmitter comprising:

• a first transmission coil as a first electrode;
• a second electrode forming a capacitor with the first electrode;
• a voltage source configured to apply a voltage to any one of the first or second electrodes;
• and
• a detection circuitry connected to any one of the first or second electrodes for detecting the capacitance change of the capacitor based on a current flowing through the capacitor such that a position of the receiver is determined with respect to the transmitter.

A method of detecting a receiver by a transmitter via a capacitance change, the method comprising:

• providing, in the transmitter, a first transmission coil as an electrode;
• applying a voltage to the electrode;
• and
• detecting a capacitance change of a capacitor based on a current flowing through the capacitor, wherein the capacitor is formed by the electrode and a ground or the capacitor is formed by the electrode and the receiver, such that a position of the receiver is determined with respect to the transmitter.

A transmitter for detecting a receiver via a capacitance change, the transmitter comprising:

• a first transmission coil as an electrode,
• a voltage source configured to apply a voltage to the electrode;
• and
• a detection circuitry connected to the first electrode for detecting the capacitance change of a capacitor based on a current flowing through the capacitor such that a position of the receiver is determined with respect to the transmitter, wherein the capacitor is formed by the electrode and a ground or the capacitor is formed by the electrode and the receiver.