Abstract: A plasma generating device intended to induce a flow in a fluid via plasma generation includes a dielectric separating two electrodes and a power supply. The first electrode is exposed to a fluid flow while the second electrode is positioned under the dielectric. The power supply is electrically coupled to a switch and the first and second electrodes. When the power supply is energized by repeated action of the switch, it causes a pulsed DC current between the electrodes which causes the fluid to ionize generating a plasma. The generation of the plasma induces a force with a velocity component in the fluid.

Abstract: A plasma generating device intended to induce a flow in a fluid via plasma generation includes a dielectric separating two electrodes and a power supply. The first electrode is exposed to a fluid flow while the second electrode is positioned under the dielectric. The power supply is electrically coupled to a switch and the first and second electrodes. When the power supply is energized by repeated action of the switch, it causes a pulsed DC current between the electrodes which causes the fluid to ionize generating a plasma. The generation of the plasma induces a force with a velocity component in the fluid.

Abstract: An exciter assembly supplies current to a superconducting load. The exciter assembly includes a transformer for generating the current and an optical emitter and an optical receiver. The transformer includes a stationary winding portion having a stationary winding and a rotatable winding portion having a rotatable winding that outputs the current for the superconducting load. The optical emitter and the optical receiver define an optical path over which information is exchanged between the stationary winding portion and the rotatable winding portion.

Abstract: An exciter assembly for supplying power to a superconducting load, such as a superconducting field coil, disposed within a cryogenic region of a rotating machine. The exciter assembly provides an efficient and reliable approach for transferring the electrical power energy across a rotating interface and for controlling the ramp up and regulation of field excitation current in the field coil. In particular, the invention provides a controlled recirculation path for current flowing through the field coil. The exciter assembly includes a transformer having a primary winding and a secondary winding, a sensor which provides a control signal indicative of the flow of field excitation current to the superconducting load; and a current regulator which is disposed in the rotating reference frame and, on the basis of the control signal, regulates the field excitation current to a predetermined set.

Abstract: An exciter assembly for supplying power to a superconducting load, such as a superconducting field coil, disposed within a cryogenic region of a rotating machine. The exciter assembly provides an efficient and reliable approach for transferring the electrical power energy across a rotating interface and for controlling the ramp up and regulation of field excitation current in the field coil. In particular, the invention provides a controlled recirculation path for current flowing through the field coil. The exciter assembly includes a transformer having a primary winding and a secondary winding, a sensor which provides a control signal indicative of the flow of field excitation current to the superconducting load; and a current regulator which is disposed in the rotating reference frame and, on the basis of the control signal, regulates the field excitation current to a predetermined set.

Abstract: Methods and apparatus for cooling systems for cryogenic power conversion electronics are provided. The invention includes systems having electronic power conversion apparatus comprising at least one cryogenically operated semiconductor switch and at least one cryogenically operated capacitor and cooling means for cryogenically cooling the at least one cryogenically operated semiconductor switch and the at least one cryogenically operated capacitor to a temperature between 90K to 236K. The systems can also include input/output means for supplying power to said power conversion apparatus and receiving power from said power conversion apparatus. In alternative embodiments, liquid cryogens can be used in heat exchange systems in conjunction with refrigeration cold heads or heat pipes. In these embodiments, the cryogen can be recondensed if boiled.

Abstract: An electronic power conversion circuit includes cryogenically cooled MOSFET power switching devices arranged in a switch-mode configuration and responsive to control signals for reducing capacitive discharge and commutation losses in the circuit by controlling the period between switch-on and switch-off time (i.e., “deadtime”) of the MOSFET devices. When one of the MOSFET devices of the circuit is switched off, the opposing MOSFET, after the short deadtime period, is switched on to serve as a commutating device rather, than the opposing MOSFET's intrinsic drain-source diode. The power conversion circuit may include a half-bridge circuit or combinations thereof.

Abstract: The invention provides an apparatus for supplying power to superconducting loads includes a current source, a cryogenic region (e.g., a cryogenic chamber), a first switching device in series between the current source and a superconducting load, and a second switching device in parallel with the superconducting load. The switching devices are arranged so that, when the first is closed and the second is open, recharging current is supplied to the superconducting load. The second switching device serves as a shunt. When it is closed and the first is open, current recirculates through the persistent (or partially persistent) superconducting load. The invention also provides a superconducting magnet incorporating such a power supply.

Abstract: The invention is an inductive device featuring very low losses even in circuits which supply more than about 10 kilowatts of power. The device includes an inductor comprising a core consisting primarily of a highly permeable magnetic material and at least one winding of a high temperature superconducting conductor contained substantially within the core and in spaced relation with respect to the core sufficient to maintain its electrical integrity, refrigeration means for cryogenically cooling at least the conductor winding portion of the inductor to a temperature at which each conductor winding exhibits superconductivity, and input/output means for providing power to and receiving power from each conductor winding. Also disclosed are a balancing choke and a circuit embodying a common mode inductor made in accordance with the invention.

Abstract: Methods and apparatus for cooling systems for cryogenic power conversion electronics are provided. The invention includes systems having electronic power conversion apparatus comprising at least one cryogenically operated semiconductor switch and at least one cryogenically operated capacitor and cooling means for cryogenically cooling the at least one cryogenically operated semiconductor switch and the at least one cryogenically operated capacitor to a temperature between 90K to 236K. The systems can also include input/output means for supplying power to said power conversion apparatus and receiving power from said power conversion apparatus. In alternative embodiments, liquid cryogens can be used in heat exchange systems in conjunction with refrigeration cold heads or heat pipes. In these embodiments, the cryogen can be recondensed if boiled.

Abstract: The invention provides an apparatus for supplying power to superconducting loads includes a current source, a cryogenic region (e.g., a cryogenic chamber), a first switching device in series between the current source and a superconducting load, and a second switching device in parallel with the superconducting load. The switching devices are arranged so that, when the first is closed and the second is open, recharging current is supplied to the superconducting load. The second switching device serves as a shunt. When it is closed and the first is open, current recirculates through the persistent (or partially persistent) superconducting load. The invention also provides a superconducting magnet incorporating such a power supply.

Abstract: A control circuit generates signals for controlling the sequence in which selected input signals are carried across the terminals of a polyphase switching conversion circuit. The control circuit includes switching elements galvanically isolated from the selected input signals with the control signals electrically isolated from the switching devices. The control circuit for the conversion circuit is, in essence, electrically isolated from the conversion circuit. The control circuit is configured to have a topology analogous to that of the switching converter and includes conventional switching diodes as well as a light generating device optically coupled to a light sensor which, in response to detection of light from the optically coupled light generating device, provides a control signal to a corresponding switching device. The control circuit also includes a source of regulated and electrically isolated power to operate drive circuitry for the switching devices.

Abstract: Methods and apparatus for uninterruptible power supply (UPS) systems are provided. The UPS systems are configured to provide the advantages of an in-line device, and operate in a quasi-standby mode. The UPS includes a rectifier unit and inverter arranged to nominally deliver a portion (e.g. up to about 20%) of the primary AC power supply to a critical load through an output transformer. The rectifier unit preferably includes internal energy storage capabilities, such as a capacitor and inductor. The remaining portion of the AC power supply is nominally supplied directly to the critical load and is controlled by a transfer switch and the output transformer. When a fault is detected in the main AC power supply, the transfer switch switches to a faulted position and power is supplied from the rectifier inductor and capacitor or from a battery to the load through the inverter.

Abstract: A control circuit generates signals for controlling the sequence in which selected input signals are carried across the terminals of a polyphase switching conversion circuit. The control circuit includes switching elements galvanically isolated from the selected input signals with the control signals electrically isolated from the switching devices. The control circuit for the conversion circuit is, in essence, electrically isolated from the conversion circuit. The control circuit is configured to have a topology analogous to that of the switching converter and includes conventional switching diodes as well as a light generating device optically coupled to a light sensor which, in response to detection of light from the optically coupled light generating device, provides a control signal to a corresponding switching device. The control circuit also includes a source of regulated and electrically isolated power to operate drive circuitry for the switching devices.

Abstract: A control circuit generates signals for controlling the sequence in which selected input signals are carried across the terminals of a polyphase switching conversion circuit. The control circuit includes switching elements galvanically isolated from the selected input signals with the control signals electrically isolated from the switching devices. The control circuit for the conversion circuit is, in essence, electrically isolated from the conversion circuit. The control circuit is configured to have a topology analogous to that of the switching converter and includes conventional switching diodes as well as a light generating device optically coupled to a light sensor which, in response to detection of light from the optically coupled light generating device, provides a control signal to a corresponding switching device. The control circuit also includes a source of regulated and electrically isolated power to operate drive circuitry for the switching devices.

Abstract: A cryogenically cooled circuit, operating at temperatures at which inductors windings of the circuit exhibit superconducting characteristics, provides unique advantages in high performance, preferably high power circuits. Portions of the circuit (or the entire circuit), as opposed to, for example only the superconducting elements (i.e., inductor winding), are refrigerated to cryogenic temperatures. Advantages in the characteristics of not only the superconducting based components but also the diodes, and gating elements such as MOSFET's, yield a uniquely advantageous circuit enabling the operation of, for example, a switching power supplies, frequency converters, and motor speed controllers with increased performance and efficiency. Size, component count, and stability are benefits attained by cryogenically cooling the entire circuit configuration.

Abstract: A method of (and apparatus for) extracting the fundamental pitch period of a complex electrical signal V.sub.2 (t), that includes the serial steps of deriving a time varying reference signal V.sub.ref (t) from the complex electrical signal V.sub.2 (t), which reference signal V.sub.ref (t) adapts continuously (i.e., each cycle of the complex electrical signal) to peak amplitude excursions of the complex electrical signal V.sub.2 (t); sensing ascending values of the signal V.sub.2 (t) to a first point at which the maximum magnitude of the signal V.sub.2 (t) of one polarity is reached and reversal of direction thereof occurs; storing the first substantially instantaneous difference in magnitude between the complex electrical signal V.sub.2 (t) and the time varying reference V.sub.ref (t) at the point of maximum magnitude of the signal V.sub.2 (t); thereafter sensing a point at which the magnitude of the signal V.sub.

Abstract: A transducer for converting an electrical current signal to a pneumatic pressure. A solid state element such as piezo-electric flapper element 48 is used to vary the pressure drop through a nozzle 46 to provide a controlled pressure supply 28. A micro-power electronic circuit 59 controls the flapper. A solid state pressure sensor 24 detects the output pressure and provides a feedback signal for use in a negative feedback loop to control the flapper element. The flapper element may be triangularly shaped to reduce its responsiveness to relatively low frequency mechanical vibrations. In a exemplary embodiment, where intrinsic safety requirements limit terminal voltages, the flapper element is driven by a transconductance amplifier 94 which is powered through a shunt regulator 82 and a voltage tripler 92. The shunt regulator provides operating potentials which are derived from the signal current.