Wireless power transmitters for transmitting power at extended separation distances utilizing concave shielding

A base station for a wireless power transfer system at an operating frequency selected from a range of about 87 kilohertz (kHz) to about 360 kHz, the base station comprising:

• an interface surface;
• a control and communications unit;
• an inverter circuit configured to receive input power and convert the input power to a power signal;
• a shielding comprising a ferrite core including a magnetic backing and a magnetic ring, the magnetic backing and the magnetic ring, in combination, defining a concave cavity, the magnetic ring comprising a bottom portion, a top portion, and an inner sidewall between the bottom portion and the top portion, the inner sidewall defining an outward extending shape that extends radially outward from the bottom portion of the magnetic ring to the top portion of the magnetic ring;
• and
• a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and positioned within the concave cavity of the shielding and radially inward from the inner sidewall of the magnetic ring, and
• wherein the outward extending shape of the inner sidewall focuses a magnetic field produced by the coil inward toward a center of the coil to enable coupling with the power receiver positioned proximate to the center of the coil.

A power transmitter for wireless power transfer at an operating frequency selected from a range of about 87 kilohertz (kHz) to about 360 kHz, the power transmitter comprising:

• a control and communications unit;
• an inverter circuit configured to receive input power and convert the input power to a power signal;
• a shielding comprising a ferrite core including a magnetic backing and a magnetic ring, the magnetic backing and the magnetic ring, in combination, defining a concave cavity, the magnetic ring comprising a bottom portion, a top portion, and an inner sidewall between the bottom portion and the top portion, the inner sidewall defining an outward extending shape that extends radially outward from the bottom portion of the magnetic ring to the top portion of the magnetic ring and defining one or more of a slope, a curve, or combinations thereof;
• and
• a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and positioned within the concave cavity of the shielding and radially inward from the inner sidewall of the magnetic ring, the coil including a first layer of the wound Litz wire and a second layer of the wound Litz wire, each of the first layer and the second layer including a number of turns in a range of about 2 turns to about 5 turns, and
• wherein the outward extending shape of the inner sidewall focuses a magnetic field produced by the coil inward toward a center of the coil to enable coupling with the power receiver positioned proximate to the center of the coil.