Wireless power transfer system having an electric field shield member

A wireless power transfer system comprising:

• a power transmitter including a high frequency power converter circuit that includes a switching circuit and that is configured to convert a direct current power into a high frequency power using the switching circuit, a power transmitter coil connected to an output of the high frequency power converter circuit, and an electric field shield member configured to suppress electric field noise radiated from the power transmitter coil, the electric field shield member including an open-loop shaped conductor having a curvature which follows a curvature of the power transmitter coil, the electric field shield member includes a plurality of strip shaped conductors protruding from the open-loop shaped conductor and crossing the power transmitter coil, and
• one of the following:
• an inner perimeter and an outer perimeter of the open-loop shaped conductor are each smaller than an inner perimeter of the power transmitter coil, or
• the inner perimeter and the outer perimeter of the open-loop shaped conductor are each larger than an outer perimeter of the power transmitter coil;
• and
• a power receiver including a power receiver coil to which electric energy is applied from the power transmitter coil and a load circuit connected to the power receiver coil, wherein
• the power receiver coil is arranged such that an equivalent capacitance between the power transmitter coil and the electric field shield member becomes greater than an equivalent capacitance between the power transmitter coil and the power receiver coil during a power transmitting operation.

A wireless power transfer system comprising:

• a power transmitter including a high frequency power converter circuit that includes a switching circuit and that is configured to convert a direct current power into a high frequency power using the switching circuit, a power transmitter coil connected to an output of the high frequency power converter circuit, and an electric field shield member configured to suppress electric field noise radiated from the power transmitter coil, the electric field shield member including an open-loop shaped conductor having a curvature which follows a curvature of the power transmitter coil;
• and
• a power receiver including a power receiver coil to which electric energy is applied from the power transmitter coil and a load circuit connected to the power receiver coil, wherein
• the power receiver coil is arranged such that an equivalent capacitance between the power transmitter coil and the electric field shield member becomes greater than an equivalent capacitance between the power transmitter coil and the power receiver coil during a power transmitting operation, and
• the electric field shield member intermittently crosses the power transmitter coil in a plan view, such that first portions of the open-loop shaped conductor are positioned within an inner perimeter of the power transmitter coil and second portions of the open-loop shaped conductor are positioned outside of an outer perimeter of the power transmitter coil, and the first and second portions are alternately positioned about a perimeter of the open-loop shaped conductor.