Rohm Co., Ltd.

Tomoya Morinaga

Masatoshi Watanabe

Tatsuya Iwasaki

Manabu Miyata

A transmission antenna includes a resonance capacitor and a transmission coil coupled in series. A driver includes a bridge circuit that applies a driving voltage to the transmission antenna. A current sensor detects a current IS that flows through the bridge circuit. A foreign object detector detects the current IS that flows through the bridge circuit while changing the switching frequency applied to the bridge circuit. The foreign object detector judges the presence or absence of a foreign object based on the detection result.

Wireless power transmitter

A wireless power transmitter transmitting a power signal to a wireless power receiver, includes: a transmission antenna; an inverter circuit applying an AC driving signal to the transmission antenna; and a control circuit controlling the inverter circuit. The control circuit includes: a demodulator demodulating a control signal received by the transmission antenna from the wireless power receiver; a transmission power measurement part measuring transmission power to generate transmission power data; and a logic circuit that controls the inverter circuit based on power control data included in the control signal to change the transmission power, control the inverter circuit based on the control signal to be transmitted to the wireless power receiver to modulate the power signal, and perform foreign object detection by a power loss method based on transmission power data and reception power data included in the control signal. The logic circuit is configured to perform a calibration sequence.

Wireless power transmitter, control circuit thereof, charger, and calibration method of foreign object detection by power loss method

A transmission antenna includes a transmission coil, and transmits an electric power signal. A driver applies a driving signal to the transmission antenna. A first temperature sensor measures the temperature of the transmission coil, and generates a first temperature signal. A second temperature sensor measures the temperature of an interface surface on which an electronic device mounting a wireless power receiving apparatus is to be placed, and generates a second temperature signal. A control circuit controls the electric power signal according to the difference between the first temperature signal Sand the second temperature signal.

Apparatus and method for wireless power transmission

A wireless power transmitter for transmitting a power signal to a wireless power receiver is disclosed. The transmitter includes a transmission antenna, an inverter circuit including a plurality of switches; and a control circuit configured to demodulate a control signal received by the transmission antenna from the transmitter and control the inverter circuit based on power control data included in the control signal. The control circuit is configured to select among a first, second and third mode. For example, in the first mode in which a first pair including first and second switches and a second pair including third and fourth switches are both complementarily switched at a duty ratio of 50%, and a phase difference of the first pair and the second pair is changed between a minimum value and a maximum value depending on a transmission power, and the inverter circuit performs a full-bridge operation.

Wireless power transmitter, control circuit and control method thereof, and charger

A demodulator is mounted on a wireless power transmitter that conforms to the Qi standard, and demodulates an amplitude modulated signal superimposed on a coil current Ithat flows through a primary coil of a transmission antenna, or otherwise on a coil voltage across both ends of the primary coil. Multiple demodulating units are each configured to have respectively different configurations, to operate in parallel, to extract a demodulated component from the coil current Ior otherwise from the coil voltage, and to generate baseband signals as demodulated signals. A signal processing unit employs a baseband signal that is correctly received, from among the multiple baseband signals generated by the multiple demodulating units, based on an error detection result obtained using a checksum.

Growing community of inventors

Kyoto, Japan

Tomoya Morinaga