Abstract: An apparatus (e.g., an inductor system) includes an elongate magnetic core, at least one coil wrapped around the magnetic core and a spacer configured to separate an inner side of the at least one coil from the magnetic core to provide a coolant passage between the inner side of the at least one coil and the magnetic core. The apparatus further includes at least one flux concentrator body positioned on an outer side of the at least one coil and configured to concentrate a magnetic flux on the outer side of the at least one coil. In some embodiments, the apparatus includes a frame configured to support the magnetic core, the at least one coil and the at least one flux concentrator body. In further embodiments, the at least one flux concentrator body may be mounted on at least one wall of an enclosure or chassis.

Abstract: An apparatus includes at least one heat sink and first and second electronic assemblies mounted on the at least one heat sink at respective first and second mounting sites and configured to unequally (e.g., at least partially non-concurrently) produce heat. At least one heat pipe is thermally coupled to the at least one heat sink and extends between locations proximate the first and second mounting sites. For example, the first and second electronic assemblies may be components of respective subsystems of an uninterruptible power supply (UPS), such as a rectifier and a battery converter, that generate heat in an at least partially non-concurrent manner.

Abstract: A fault in a DC power source, such as a battery string or a string of photovoltaic cells, is identified by detecting a change in an AC component of a residual current of the DC power source. In some embodiments, the DC power source is coupled to at least one DC bus and the methods further include generating an AC voltage on the at least one DC bus. For example, the DC power source may be coupled to a modulated DC bus of an uninterruptible power supply (UPS) system comprising an inverter having an input coupled to the DC bus. The inverter may be configured to generate an AC output voltage and the AC component has a frequency that is a harmonic of a fundamental frequency of the AC output voltage, such as a third harmonic of the fundamental frequency of the AC output voltage.

Abstract: An apparatus includes at least one heat sink and first and second electronic assemblies mounted on the at least one heat sink at respective first and second mounting sites and configured to unequally (e.g., at least partially non-concurrently) produce heat. At least one heat pipe is thermally coupled to the at least one heat sink and extends between locations proximate the first and second mounting sites. For example, the first and second electronic assemblies may be components of respective subsystems of an uninterruptible power supply (UPS), such as a rectifier and a battery converter, that generate heat in an at least partially non-concurrent manner.

Abstract: A PV system includes a plurality of PV strings each having an optimal string voltage at which a string output power is maximized. The PV strings are connected to a DC link in a parallel arrangement such that each PV strings operates at a variable DC link voltage. A PV inverter is connected to the DC link to receive a DC output, with the PV inverter controlling the DC link voltage. Delta DC/DC converters are connected to the PV strings, with each DC/DC converter receiving the DC link voltage from the DC link and providing a tuning voltage to the DC link voltage at which its respective PV string operates in order to bring the string voltage for that PV string to its optimal string voltage. The tuning voltage of each delta DC/DC converter is the difference between the DC link voltage and a respective optimal string voltage.

Abstract: An apparatus (e.g., an inductor system) includes an elongate magnetic core, at least one coil wrapped around the magnetic core and a spacer configured to separate an inner side of the at least one coil from the magnetic core to provide a coolant passage between the inner side of the at least one coil and the magnetic core. The apparatus further includes at least one flux concentrator body positioned on an outer side of the at least one coil and configured to concentrate a magnetic flux on the outer side of the at least one coil. In some embodiments, the apparatus includes a frame configured to support the magnetic core, the at least one coil and the at least one flux concentrator body. In further embodiments, the at least one flux concentrator body may be mounted on at least one wall of an enclosure or chassis.

Abstract: A resonant tank circuit has an output port configured to be coupled to a load comprising a current-controlled semiconductor device, such as a diode, thyristor, transistor or the like. A voltage generator circuit is configured to intermittently apply voltages to an input port of the resonant tank circuit in successive intervals having a duration equal to or greater than a resonant period of the resonant tank circuit. Such an arrangement may be used, for example, to drive a static switch.

Abstract: A PV system includes a plurality of PV strings each having an optimal string voltage at which a string output power is maximized. The PV strings are connected to a DC link in a parallel arrangement such that each PV strings operates at a variable DC link voltage. A PV inverter is connected to the DC link to receive a DC output, with the PV inverter controlling the DC link voltage. Delta DC/DC converters are connected to the PV strings, with each DC/DC converter receiving the DC link voltage from the DC link and providing a tuning voltage to the DC link voltage at which its respective PV string operates in order to bring the string voltage for that PV string to its optimal string voltage. The tuning voltage of each delta DC/DC converter is the difference between the DC link voltage and a respective optimal string voltage.

Abstract: A fault in a DC power source, such as a battery string or a string of photovoltaic cells, is identified by detecting a change in an AC component of a residual current of the DC power source. In some embodiments, the DC power source is coupled to at least one DC bus and he methods further include generating an AC voltage on the at least one DC bus. For example, the DC power source may be coupled to a modulated DC bus of an uninterruptible power supply (UPS) system comprising an inverter having an input coupled to the DC bus. The inverter may be configured to generate an AC output voltage and the AC component has a frequency that is a harmonic of a fundamental frequency of the AC output voltage, such as a third harmonic of the fundamental frequency of the AC output voltage.

Abstract: A resonant tank circuit has an output port configured to be coupled to a load comprising a current-controlled semiconductor device, such as a diode, thyristor, transistor or the like. A voltage generator circuit is configured to intermittently apply voltages to an input port of the resonant tank circuit in successive intervals having a duration equal to or greater than a resonant period of the resonant tank circuit. Such an arrangement may be used, for example, to drive a static switch.

Abstract: A power converter apparatus, such as an uninterruptible power supply (UPS), includes an inverter having an input coupled to a first DC bus and a second DC bus and configured to generate an AC output with respect to a neutral terminal at a phase output terminal thereof. The apparatus further includes first and second neutral coupling circuits, each configured to selectively couple the first DC bus and the second DC bus to the neutral terminal, and a control circuit configured to cause interleaved operation of the neutral coupling circuits.

Abstract: An apparatus, such as an inverter or rectifier in a double-conversion UPS, includes a plurality of power switching devices, such as IGBTs, coupled in parallel. A drive circuit is coupled to the power switching devices at a plurality of drive nodes and configured to drive the drive nodes responsive to a drive control signal. A monitoring circuit is coupled to the drive circuit and configured to determine respective statuses of respective ones of the power switching devices. The monitoring circuit may be configured to generate respective measures of drive delivered to respective ones of the drive nodes.

Abstract: A power converter apparatus, such as an uninterruptible power supply (UPS), includes an inverter having an input coupled to a first DC bus and a second DC bus and configured to generate an AC output with respect to a neutral terminal at a phase output terminal thereof. The apparatus further includes first and second neutral coupling circuits, each configured to selectively couple the first DC bus and the second DC bus to the neutral terminal, and a control circuit configured to cause interleaved operation of the neutral coupling circuits.

Abstract: An inductor includes an elongate magnetic core, a coil wrapped around the core and a spacer that separates the coil from the core to provide a coolant passage between the coil and the core. The coolant passage may include an air passage that extends substantially parallel to an axis of the core and that has first and second openings proximate respective first and second ends of the core. The coil may include a twisted bundle of individually insulated conductors. The inductor may be housed in a flux-tolerant compartment, i.e., a conductive aluminum structure that supports eddy currents with relatively acceptable resistive losses.

Abstract: Uninterruptible Power Supply (UPS) systems and methods for a communications signal distribution system, such as a cable television (CATV) signal distribution system that distributes a communication signal and an Alternating Current (AC) power over a coaxial cable having a conductor and a sheath, include an input neutral line and an input voltage line. A first circuit is configured to convert an input voltage between the input neutral line and the input voltage line into first and second complementary Direct Current (DC) voltages. A second circuit is configured to convert the first and second complementary DC voltages into an AC voltage between an output neutral line and an output voltage line, and to connect the output neutral line to a coaxial cable sheath and the output voltage line to a coaxial cable conductor. The first and second circuits are configured to connect the input neutral line to the output neutral line without an intervening transformer winding.

Abstract: An inductor includes an elongate magnetic core, a coil wrapped around the core and a spacer that separates the coil from the core to provide a coolant passage between the coil and the core. The coolant passage may include an air passage that extends substantially parallel to an axis of the core and that has first and second openings proximate respective first and second ends of the core. The coil may include a twisted bundle of individually insulated conductors. The inductor may be housed in a flux-tolerant compartment, i.e., a conductive aluminum structure that supports eddy currents with relatively acceptable resistive losses.

Abstract: An uninterruptible power supply (UPS) system includes an AC input port, a DC input port, and an output port configured to be connected to an AC load. A rectifier circuit is coupled to the AC input port, and a power transfer control circuit is coupled to the rectifier circuit output, the DC input port and the output port. The power transfer control circuit produces a DC voltage at the AC load from a rectified voltage produced by the rectifier circuit in a first mode of operation and from a DC voltage at the DC input port in a second mode of operation. A current control circuit, e.g., a boost regulator, may control a current from at least one of the rectifier circuit and the DC input port responsive to a control input. A DC/DC converter circuit may be coupled between the DC input port and the output port.

Abstract: A circuit protection apparatus includes first and second terminals configured to be coupled to respective first and second circuit nodes of a circuit. A switching circuit is operative to intermittently couple a clamp circuit, for example, a metal oxide varistor (MOV) or a silicon avalanche suppressor (SAS), between the first and second terminals. The switching circuit may be operative to intermittently couple the clamp circuit between the first and second terminals responsive to a voltage at at least one of the first and second terminals. The switching circuit may include a switch that is operative to couple and decouple the clamp circuit between the first and second terminals responsive to a control input applied thereto. A control circuit may be operative to generate the control input responsive to a voltage at at least one of the first and second terminals.

Abstract: Uninterruptible Power Supply (UPS) systems and methods for a communications signal distribution system, such as a cable television (CATV) signal distribution system that distributes a communication signal and an Alternating Current (AC) power over a coaxial cable having a conductor and a sheath, include an input neutral line and an input voltage line. A first circuit is configured to convert an input voltage between the input neutral line and the input voltage line into first and second complementary Direct Current (DC) voltages. A second circuit is configured to convert the first and second complementary DC voltages into an AC voltage between an output neutral line and an output voltage line, and to connect the output neutral line to a coaxial cable sheath and the output voltage line to a coaxial cable conductor. The first and second circuits are configured to connect the input neutral line to the output neutral line without an intervening transformer winding.

Abstract: An uninterruptable power supply system for producing an AC voltage from at least one of a DC power source or an AC power source includes an input terminal configured to receive an AC voltage from an AC power source, and an inverter operative to produce an AC voltage at an output thereof from a DC power source. A ferroresonant transformer circuit includes a transformer having an input winding, a output winding, and a third winding that forms part of a resonant circuit that produces saturation in the output winding when an AC voltage on the input winding exceeds a predetermined amplitude. A transformer input control circuit is coupled to the input terminal and to the inverter output and is operative to couple at least one of the input terminal and the inverter output to the input winding.