Contactless power supply device and transmitter device

#This application claims the priority of Japanese Patent Application Number 2019-156003 filed on Aug. 28, 2019 which is hereby incorporated by reference.

#The disclosure relates to a contactless power supply device, and to a power transmitter can be used in a contactless power supply device.

#Methods known for transmitting power through the air without relying on metal contacts or the like, i.e., contactless power supply (also known as wireless power supply) have been the subject of research.

#FIG. 1 is a diagram illustrating a schematic overview of a contactless power supply device including a power transmitter according to an embodiment or embodiments;

#FIG. 2 is a diagram illustrating one example of another inverter circuit;

#FIG. 3A is a diagram illustrating an example of current flowing through switching elements when the coupling coefficient between a transmitter coil and an auxiliary coil is smaller than the coupling coefficient between the transmitter coil and a receiver coil; FIG. 3B is a diagram illustrating an example of current flowing through switching elements when the coupling coefficient between a transmitter coil and an auxiliary coil equals the coupling coefficient between the transmitter coil and a receiver coil; FIG. 3C is a diagram illustrating an example of current flowing in switching elements when the coupling coefficient between a transmitter coil and an auxiliary coil is greater than the coupling coefficient between the transmitter coil and a receiver coil;

#A contactless power supply device according to an embodiment is described below with reference to the drawings. A contactless power supply device according to an embodiment has a device on the power transmitting side (referred to below as simply a power transmitter device) which includes a coil used for power transmission (referred to below as a transmitter coil), an auxiliary coil provided capable of electromagnetic coupling, and a capacitive element that can connect to the auxiliary coil. Hereby the contactless power supply device may establish an amount of delay that is suitable for the phase of the current flowing in the switching elements in the power supply circuit with respect to the phase of the voltage applied to the switching elements in the power supply circuit, which supplies alternating-current power to the transmitter coil to improve the power transmission efficiency. Because it is not necessary to raise the Q factor of the resonant circuit in the device on the power receiving side (referred to below as the receiver device), there is no need to include a large coil for power receiving (referred to below as the receiver coil) in the resonant circuit; consequently, this simplifies the contactless power supply device overall.

#FIG. 1 is a schematic overview of a contactless power supply device including a power transmitter according to an embodiment; as illustrated in FIG. 1, the contactless power supply device 1 includes a power transmitter 2, and a power receiver 3 to which power is transmitted without contact through the air from the power transmitter 2. The power transmitter 2 includes a power supply circuit 10, a transmitter coil 13, and auxiliary call 14, a capacitor 15, and a control circuit 16. Meanwhile, the power receiver 3 includes a receiver coil 21 and a resonant capacitor 22 which make up the resonant circuit 20, and a receiver circuit 23. The contactless power supply device 1 according to an embodiment transmits power through series resonance (NS method) wherein the resonant circuit 20 on the power receiving side resonates with respect to the alternating-current power supplied to the transmitter coil 13 without employing the resonance on the power transmitting side. The contactless power supply device 1 may transmit power through parallel resonance (NP method) wherein the resonant circuit 20 on the power receiving side resonates with respect to the alternating-current power supplied to the transmitter coil 13 without employing the resonance on the power transmitting side.

#First the power transmitter 2 is described. The power supply circuit 10 supplies alternating-current power to the transmitter coil 13. Therefore, the power supply circuit 10 possesses a power source 11, and an inverter circuit 12.