Methods and apparatus for reducing flux cancellation in ferrite of double couple inductive power transfer systems

A method for transmitting charging power wirelessly to a load, the method comprising:

• generating an alternating current via a first coil under influence of a first alternating magnetic field, the first coil wound around at least one portion of a ferrite structure comprising:
• a first ferrite portion,
• a second ferrite portion comprising at least a first ferrite leg, a second ferrite leg, and a third ferrite leg, each physically separated from the first ferrite portion by a first distance, and
• a third ferrite portion positioned between the second ferrite leg and the first ferrite portion and physically contacting the second ferrite leg;
• and
• wirelessly transmitting power via a second alternating magnetic field generated by driving a second coil with the alternating current, wherein one of the first and second coils comprises at least a first winding wound in a first layer around the second ferrite lea and a second winding wound in a second layer around the first layer and has a control coil wound in a third layer around the first or second coil comprising the first and second windings, the first layer connected to the second layer by a capacitor.

An apparatus for transmitting charging power wirelessly to a load, the apparatus comprising:

• first means for channeling magnetic flux;
• second means for channeling magnetic flux comprising at least a first leg, a second leg, and a third leg, each physically separated from the first means for channeling magnetic flux by a first distance, and the second leg being located between the first leg and the third leg;
• third means for channeling magnetic flux positioned between the second leg and the first means for channeling magnetic flux and physically contacting the second leg;
• means for generating an alternating current under influence of an alternating magnetic field wound around the second leg, the generating means comprising at least a first winding wound in a first layer around the second ferrite leg and a second winding wound in a second layer around the first layer, the first layer connected to the second layer by a capacitor;
• and
• means for reducing or preventing generation of the alternating current wound in a third layer around the means for generating an alternating current under influence of an alternating magnetic field.

A method for manufacturing a double couple transformer configured to transmit charging power wirelessly to a vehicle, the method comprising:

• providing at least one ferrite structure comprising:
• a first ferrite portion,
• a second ferrite portion comprising at least a first ferrite leg, a second ferrite leg, and a third ferrite leg, each physically separated from the first ferrite portion by a first distance, and
• a third ferrite portion positioned between the second ferrite leg and the first ferrite portion and physically contacting the second ferrite leg;
• winding a coil around the second ferrite leg such that the coil is configured to generate an alternating current under influence of an alternating magnetic field, the coil comprising at least a first winding wound in a first layer around the second ferrite leg and a second winding wound in a second layer around the first layer, the first layer connected to the second layer by a capacitor;
• and
• winding a control coil in a third layer around the coil.