A resonant inductive power transfer circuit has a power converter to supply to a load, and the converter is concurrently controlled to create a controlled reactance that substantially compensates for variability in the coupling with the another resonant inductive power transfer circuit and/or changes in the load supplied by the power converter.

Systems and methods for using parasitic capacitance of a transformer as an element in a resonant converter are provided. Aspects include determining a parasitic capacitance associated with a transformer, determining a resonant circuit configuration based at least in part on the parasitic capacitance associated with the transformer, and providing a resonant converter comprising the resonant circuit and the transformer.

A resonant DC/DC converter which has a first DC link, preferably including a first DC link capacitor; a DC/AC converter which has a first plurality of N>1 converter bridges connected in parallel to the first DC link; each converter bridge comprising a plurality of switches each of which may be switched between a conducting state and a non-conducting state. The resonant DC/DC converter also includes an AC intermediate circuit having an input connected to an output of the DC/AC converter and comprising: a transformer, preferably a medium frequency transformer, having a primary side and a secondary side; the primary side comprising at least one primary winding; a first plurality of N capacitors, wherein for each converter bridge, a different one from the first plurality of capacitors is connected between said converter bridge and the at least one primary winding.

The converter includes a primary-side winding, a secondary-side winding, a resonant inductor, a resonant capacitor, and a noise suppression network. The primary-side winding and the secondary-side winding form a transformer. The noise suppression network is connected between a primary-side quiescent point and a secondary-side quiescent point. The primary-side quiescent point is a direct current stable potential at an input terminal of the DC/DC converter. The secondary-side quiescent point is a direct current stable potential at an output terminal of the DC/DC converter. A first parasitic capacitance between a first terminal of the primary-side winding and the secondary-side quiescent point is equal to a second parasitic capacitance between a second terminal of the primary-side winding and the secondary-side quiescent point. A suppression current is generated by the noise suppression network, and has a direction opposite to a direction of a total noise current generated by the resonant inductor.

A resonator circuit for a contactless energy transmission system for charging electric vehicles and a contactless energy transmission system for charging electric vehicles are described. The resonator circuit may include first and second terminals, multiple windings, and first and second switching elements. The windings may be divided into first and second groups. A connection node may be arranged between the first and second groups of windings and connected via the first switching element to the first terminal, and the connection node is connected via the first group of windings to the second terminal. The second switching element may be arranged between the second group of windings and the first terminal. The first connection node may be formed in a star-shaped manner between the first group of windings, the second group of windings, and the first switching element.

An apparatus includes a rectifier having a first input coupled to a first terminal of a receiver coil and a second input coupled to a second terminal of the receiver coil, wherein the rectifier is configured to convert an alternating current voltage into a direct current voltage, a first communication network connected to the first input of the rectifier, and a second communication network connected to the second input of the rectifier, wherein the first communication network and the second communication network are controlled independently to adjust a gain of a wireless power transfer system.

A magnetic component includes a main magnetic core, a power winding coupled to the main magnetic core, a variable reluctance core element arranged in a flux path of the main magnetic core and including a saturable magnetic core and a control winding coupled to the saturable magnetic core. The control winding is isolated relative to the power winding and configured to selectively saturate a section of the saturable magnetic core.

A gate drive circuit in a switching circuit including a switching terminal connected to a node that is connected to a high-side transistor and a low-side transistor, and connected to an end of a boot-strap capacitor, a bootstrap terminal connected to another end of the bootstrap capacitor, a high-side driver having an output terminal connected to a gate of the high-side transistor, an upper power supply node connected to the bootstrap terminal, and a lower power supply node connected to the switching terminal, a low-side driver having an output terminal connected to a gate of the low-side transistor, a rectifying device for applying a constant voltage to the bootstrap terminal, and a dead time controller for controlling a length of a dead time during which the high-side transistor and the low-side transistor are simultaneously turned off, based on a potential difference between the bootstrap terminal and the switching terminal.

An apparatus includes a rectifier having a first input coupled to a first terminal of a receiver coil and a second input coupled to a second terminal of the receiver coil, wherein the rectifier is configured to convert an alternating current voltage into a direct current voltage, a first communication network connected to the first input of the rectifier, and a second communication network connected to the second input of the rectifier, wherein the first communication network and the second communication network are controlled independently to adjust a gain of a wireless power transfer system.

An apparatus includes a DC-to-AC converter comprising a first output terminal and a second output terminal. The apparatus also includes a DC-to-DC converter comprising a third output. The DC-to-AC converter is configured to receive a DC input voltage from a DC power source, and to produce a first alternating output voltage at the first output terminal, and a second alternating output voltage at the second output terminal. The DC-to-DC converter is configured receive a DC input voltage from the DC power source, and to step down the DC input voltage at the third output.