A wireless power transmission system comprising a wireless transmitter capable of transmitting power and a wireless receiver capable of receiving power such that the transmitter or receiver comprises a controller and resonant tank, and the resonant tank comprises a capacitor and an electrically tunable inductor.

Disclosed herein is an inductor comprising a primary winding. The inductor further comprises a secondary winding wound around the same core as the primary winding. The secondary winding is connected to an excitation stage that causes the secondary winding to selectively generate flux at one or more frequencies in order to vary the magnetic behaviour of the inductor.

In order to measure a choke current through a choke, a flux density of a magnetic field which is emitted by the choke is consecutively measured at a sampling rate at a location which is fixed in relation to the choke. A magnetic bias of the choke is ascertained from the measurement values of the flux density at a known choke current which occurs during operation of the choke, wherein the choke current is known only in longer time intervals than the inverse value of the sampling rate during measurement of the flux density. The actual choke current is determined from the actual measurement values of the flux density taking into account the ascertained magnetic bias.

In order to measure a choke current through a choke, a flux density of a magnetic field which is emitted by the choke is consecutively measured at a sampling rate at a location which is fixed in relation to the choke. A magnetic bias of the choke is ascertained from the measurement values of the flux density at a known choke current which occurs during operation of the choke, wherein the choke current is known only in longer time intervals than the inverse value of the sampling rate during measurement of the flux density. The actual choke current is determined from the actual measurement values of the flux density taking into account the ascertained magnetic bias.

A variable inductor includes a three-limbed core first section having an inductor winding wound about a medial limb. An air gap is disposed in the medial limb. The inductor includes a second section having a control limb in which a first end of the control limb is connected to a first outer limb of the three-limbed core, and a second end of the control limb is connected to a second outer limb of the three-limbed core. A control winding is wound about the control limb. The inductor may be used in a control circuit to control a power signal driving a transducer. The inductor may be controlled by a signal derived from a comparison of a voltage phase of a power signal to the transducer and a phase of the current traversing the transducer. A system may include the control circuit, including the variable inductor, and the transducer.

Method for producing an integrated magnetic device with variable inductance, comprising: a) making of a piezoelectric element on a first substrate; b) making of a first electrically conductive element on a face of the piezoelectric element, and fastening of the ends of the piezoelectric element to a second substrate such that the piezoelectric element is arranged facing a cavity formed between the second substrate and the piezoelectric element, the first electrically conductive element being arranged in and/or against the second substrate or against the piezoelectric element; c) removing of the first substrate; d) making of a second electrically conductive element on another face of the piezoelectric element; and further comprising the making of an electrical and/or magnetic coupling of the first and second electrically conductive elements, and the making of a magnetic element arranged against and/or in the piezoelectric element and between the electrically conductive elements.

Method for producing an integrated magnetic device with variable inductance, comprising: a) making of a piezoelectric element on a first substrate; b) making of a first electrically conductive element on a face of the piezoelectric element, and fastening of the ends of the piezoelectric element to a second substrate such that the piezoelectric element is arranged facing a cavity formed between the second substrate and the piezoelectric element, the first electrically conductive element being arranged in and/or against the second substrate or against the piezoelectric element; c) removing of the first substrate; d) making of a second electrically conductive element on another face of the piezoelectric element; and further comprising the making of an electrical and/or magnetic coupling of the first and second electrically conductive elements, and the making of a magnetic element arranged against and/or in the piezoelectric element and between the electrically conductive elements.

An inductive sensor includes a core body, a coil wound on the core body, a cavity having a fixed volume within the core body, and an epoxy mixture filling a controlled portion of the fixed volume. The controlled portion of the fixed volume filled with the epoxy mixture controls an inductance of the sensor.

An inductive sensor includes a core body, a coil wound on the core body, a cavity having a fixed volume within the core body, and an epoxy mixture filling a controlled portion of the fixed volume. The controlled portion of the fixed volume filled with the epoxy mixture controls an inductance of the sensor.

This disclosure describes systems, methods, and apparatus for waveform control, comprising: a power supply having an input terminal, and at least one output terminal for coupling to a load; a controller; a variable inductor coupled to at least one of the output terminals, the variable inductor comprising a first magnetic core having a plurality of arms, including at least a first inductor arm and a first control arm, wherein an inductance winding having one or more turns is wound around the first inductor arm, and wherein a first control winding comprising one or more turns is wound around the first control arm; and a DC current source coupled to the first control arm and the controller, the controller configured to adjust a DC bias applied by the DC current source to the first control arm to control an output waveform at the at least one output terminal.