Abstract: A first inductive element including a plurality of first subcoils, each first subcoil characterized at least in part by a geometry that comprises a winding direction and a physical size is provided. The plurality of first subcoils are in electrical communication with each other, and the geometry of each first subcoil is selected to reduce a variation in an inductive coupling between the first inductive element and a second inductive element when a gap between the first inductive element and the second inductive element varies. A method of inductive alignment using the above system is also provided.

Abstract: A first inductive element including a plurality of first subcoils, each first subcoil characterized at least in part by a geometry that comprises a winding direction and a physical size is provided. The plurality of first subcoils are in electrical communication with each other, and the geometry of each first subcoil is selected to reduce a variation in an inductive coupling between the first inductive element and a second inductive element when a gap between the first inductive element and the second inductive element varies. A method of inductive alignment using the above system is also provided.

Abstract: An inductive alignment system is provided. The system includes a power source providing a forcing function and a first inductor in communication with the power source. The first inductor exhibits a first electrical property in response to the forcing function. The system also includes a second inductor in communication with the first inductor. The second inductor exhibits a second electrical property in response to the forcing function. The system includes a comparator that compares the first electrical property with the second electrical property and generates a signal based at least in part on a deviation between the first electrical property and the second electrical property. The deviation is caused at least in part by inductive coupling between a proximate object and at least one of the first inductor and the second inductor. A method of inductive alignment using the above system is also provided.

Abstract: A method for controlling stray electromagnetic fields for a vehicle with an inductive charging system and a method for providing feedback to a vehicle operator for an inductive charging system is characterized by the addition of alignment coils to a vehicle mounted secondary coil. The methods provide sensors to detect the relative positions of the primary coil and secondary coil by determining voltages induced in the alignment coils by a magnetic field generated by the primary coil. The methods include providing feedback to the vehicle operator to guide the alignment of the secondary coil relative to the primary coil and directing the vehicle operator to position the secondary coil within an alignment zone so as to control stray electromagnetic fields.

Abstract: A method and apparatus for aligning a vehicle with an inductive charging system is characterized by the addition of alignment coils to a secondary coil on the vehicle. For efficient inductive charging, it is necessary that the vehicle mounted secondary coil be aligned with a stationary primary coil of a transformer of the inductive charging system. When the primary coil is energized, it produces a magnetic field which induces a voltage in the alignment coils as a function of the proximity of the alignment coils to the central axis of the primary coil. The voltage differential between opposed pairs of alignment coils is determined by a comparator which then generates a directional signal which can be used by the operator of the vehicle to position the vehicle for closer alignment of the vehicle secondary coil with the primary coil and more efficient charging.

Abstract: A method for aligning a vehicle with an inductive charging system is characterized by the addition of alignment coils to a secondary coil on the vehicle. For efficient inductive charging, it is necessary that the vehicle mounted secondary coil be aligned with a stationary primary coil of a transformer of the inductive charging system. When the primary coil is energized, it produces a magnetic field which induces a voltage in the alignment coils as a function of the proximity of the alignment coils to the central axis of the primary coil. The voltage differential between opposed pairs of alignment coils is determined by a comparator which then generates a directional signal which can be used by the operator of the vehicle to position the vehicle for closer alignment of the vehicle secondary coil with the primary coil and more efficient charging.

Abstract: An inductive power transfer system for a device such as battery charger on an electric vehicle includes a primary circuit having a rectifier and an H bridge inverter connected in parallel with a reactor connected in series to deliver direct current voltage to a stationary primary coil of a transformer. The system further includes a secondary circuit on the vehicle including a secondary coil and another rectifier connected in series. AC voltage from a power supply is converted to DC voltage and then transformed into a pulse width modulated high frequency square wave voltage for electromagnetic transfer from the primary coil to the secondary coil. The square wave voltage is converted back to DC voltage for delivery to a vehicle charger.

Abstract: A method and apparatus for aligning a vehicle with an inductive charging system is characterized by the addition of alignment coils to a secondary coil on the vehicle. For efficient inductive charging, it is necessary that the vehicle mounted secondary coil be aligned with a stationary primary coil of a transformer of the inductive charging system. When the primary coil is energized, it produces a magnetic field which induces a voltage in the alignment coils as a function of the proximity of the alignment coils to the central axis of the primary coil. The voltage differential between opposed pairs of alignment coils is determined by a comparator which then generates a directional signal which can be used by the operator of the vehicle to position the vehicle for closer alignment of the vehicle secondary coil with the primary coil and more efficient charging.