A separable inductive coupler for transferring electrical power across a dielectric medium using magnetic induction. Its coil geometry allows for easy disassembly of primary and secondary circuits. When primary and secondary coils are mated, an extremely low leakage inductance transformer is formed. This provides for good high frequency operation at high power density. The coupler allows electrical power transfer without metal-to-metal contact. The design allows easy removal of the primary or secondary coil from the transformer. The coil geometry has very low leakage inductance and very low high-frequency resistance which allows high frequency operation. The power transfer density is much higher than previously achieved with separable inductive couplers. Approximately 6000 watts has been transferred through a version of the present separable inductive coupler having a volume of 25.8 cubic inches, yielding a power density of 230 Watts/cubic inch. The coupler is adapted to provide a safe, convenient and weatherproof device for coupling power to a load, such as an electric vehicle to recharge its propulsion battery.

Separable inductive coupler

A magnetic field sensor comprises a magnetic field sensing cell (10) and a magnetic shield (9) comprising at least two parts (12a, 12b) separated by an air-gap (20) and surrounding the magnetic field sensing cell positioned in a cavity (11) of the magnetic shield.

Magnetic field sensor and electrical current sensor therewith

A sensor for measuring large magnitudes of A.C. current utilizes a current divider having parallel conductors and a current comparator coupled to one of the conductors so arranged as to perform first and second stages of scaling of the A.C. current to obtain an output signal from the sensor proportional to the A.C. current. The overall sensor ratio is the product of the ratios of the first and second stages, thereby permitting very large ratios to be obtained. Components of the sensor are arranged so as to cause cancellation of magnetic fields by the sensor and to make the sensor immune from incident magnetic fields.

Coaxial current sensors

A magnetic field sensor having a lateral bipolar magnetotransistor incorporating only a single emitter region and whose base region is incorporated as a well in the surface of a silicon substrate of the reverse material conduction type. The P/N junction of the base region with the silicon substrate is reverse biased by means of at least one secondary collector contact. The emitter region must be kept as shallow than 0.5 μm or be so lowly doped with impurity atoms that its resistivity is greater than 100 ohms per square or both. The sensitivity of the magnetic field sensor is approximately 100%/Tesla.

Sensitive magnetotransistor magnetic field sensor

A current sensing device includes a secondary coil positioned within the curved portion of a U-shaped primary conductor or coil. The secondary coil is surrounded by a non-ferromagnetic metallic shield to prevent capacitive coupling between the windings of the secondary coil and other nearby metallic objects. A nonconductive material is integrally formed about the U-shaped conductor and provides a cavity for receiving the secondary coil an shield in a predetermined position with respect to the U-shaped conductor. A flux guide of ferromagnetic metal, formed in an elliptical-cylindrical shape, surrounds the U-shaped conductor and the secondary coil to provide a flux steering effect to steer flux around the secondary or pick-up coil. The current sensing device is useful in measuring current in electrical utility power monitoring or watthour meter applications.

Shielded current sensing device for a watthour meter

A transducer for measuring a current, includes a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, so as to produce a second magnetic field, and a magnetic field comparision device exposed to the magnetic fields. The magnetic field comparison device includes a magnetic film bridging the flux gap. The film is alternately controllable in respective opposite directions of saturation substantially by the first magnetic field, and evaluates the measuring current in dependence of the magnetic fields. The magnetic core, the coil, the loop, and the magnetic film are substantially disposed concentrically.

Konrad Schurmann

Papers

Current- and voltage-measurement transducer