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.

An AC permanent magnet gain transformer device and its voltage regulation and control method. This device adds permanent magnet or permanent magnet assembly to the structure of traditional transformer, the magnetic pole surface of permanent magnet closely clings to laminated iron core, so that the intrinsic permanent magnetic potential of permanent magnet could be elicited under the excitation of the excitation current of primary winding, overlapped and compounded with excitation magnetic potential in the general magnetic loop of closed-loop laminated iron core, and so, it's able to induce the induction electromotive force formed after the superposition of excitation flux and permanent magnet flux at the output end of secondary winding. The method for voltage regulation and control of this invention is to: input a certain amplitude of pulse current to the primary winding in order to guarantee the generation of compound excitation effect, and change the pulse count of pulse current per unit time in order to change and adjust the input and output power of this AC permanent magnet gain transformer device. This AC permanent magnet gain transformer device and its voltage regulation and control method further enhance the power transfer efficiency of transformer device, thus make up the intrinsic spoilage of traditional winding coil and laminated iron core, and save energy.

Embodiments of a variable inductor and a communication device are generally described herein. The variable inductor may comprise a signal wire and a control wire to receive a direct current (DC) control current. The variable inductor may further comprise a magnetic material integrated with the signal wire and the control wire. When a DC control current applied to the control wires takes a first current value, an inductance between an input node and an output node on the signal wire may take a first inductance value. When the DC control current takes a second current value, the inductance between the input node and the output node may take a second inductance value.

Embodiments of a variable inductor and a communication device are generally described herein. The variable inductor may comprise a signal wire and a control wire to receive a direct current (DC) control current. The variable inductor may further comprise a magnetic material integrated with the signal wire and the control wire. When a DC control current applied to the control wires takes a first current value, an inductance between an input node and an output node on the signal wire may take a first inductance value. When the DC control current takes a second current value, the inductance between the input node and the output node may take a second inductance value.

A choke coil including a coil (6) and a core (1) including a first core part (5) inserted into a central hole of the coil (6) and a plurality of second core parts (4) disposed along the outer periphery of the coil. The first core part (5) and the second core part (4) form a closed magnetic path. The second core parts (4) are shaped so that the total sum of the areas of cross sections thereof perpendicular to the axis of the coil is greater than the area of a cross section of the first core part (5). A gap part (G) is formed in the second core parts (4), and a ferrite magnet (7) that applies a magnetic bias is disposed in the gap part (G).

A sensor device includes a power line and a semiconductor device. The semiconductor device includes an inductor. The inductor is formed using an interconnect layer (to be described later using FIG. 3). The power line and the semiconductor device overlap each other when viewed from a direction perpendicular to the semiconductor device. The semiconductor device includes two inductors. The power line extends between the two inductors when viewed from a direction perpendicular to the semiconductor device.

A voltage converter is provided that includes a variable inductor device that is disposed between an input line and an output line, a switching device that is disposed between the input line and the variable inductor device, a capacitor that is disposed between the output line and a ground line and a control circuit configured to switch an inductance value of the variable inductor device and to switch a control mode of the switching device according to a load current in the output line. The control circuit is configured to set the inductance value of the variable inductor device to a first value when the load current is less than a threshold value and set the inductance value of the variable inductor device to a second value that is smaller than the first value when the load current is higher than the threshold value.

A device for limiting a fault current for a generator, in particular of a wind turbine is provided. A first frame is made of a ferromagnetic material, wherein the first frame comprises a first frame section and a further first frame section, wherein a first gap is formed between the first frame section and the further first frame section. A first coil is wound around the first frame section, wherein the first coil is connectable to a first stator winding of a stator of the generator. A further first coil is wound around the further first frame section, wherein the further first coil is connectable to an electronic device. A first permanent magnet element is arranged inside the first gap. The first frame section and the further first frame section are formed with respect to each other such that an electromagnetic interaction between the first coil and the first permanent magnet element and the further first coil and the first permanent magnet element is provided.

A device for limiting a fault current for a generator, in particular of a wind turbine is provided. A first frame is made of a ferromagnetic material, wherein the first frame comprises a first frame section and a further first frame section, wherein a first gap is formed between the first frame section and the further first frame section. A first coil is wound around the first frame section, wherein the first coil is connectable to a first stator winding of a stator of the generator. A further first coil is wound around the further first frame section, wherein the further first coil is connectable to an electronic device. A first permanent magnet element is arranged inside the first gap. The first frame section and the further first frame section are formed with respect to each other such that an electromagnetic interaction between the first coil and the first permanent magnet element and the further first coil and the first permanent magnet element is provided.

A sensor device includes a power line and a semiconductor device. The semiconductor device includes an inductor. The inductor is formed using an interconnect layer (to be described later using FIG. 3). The power line and the semiconductor device overlap each other when viewed from a direction perpendicular to the semiconductor device. The semiconductor device includes two inductors. The power line extends between the two inductors when viewed from a direction perpendicular to the semiconductor device.