Abstract: An electric machine is provided in which the magnetic field in the air gap between the stator and the rotor rotates around the air gap while simultaneously reversing in polarity at a modulation frequency that is substantially higher than the rotational frequency of the field around the air gap. The magnetic field modulation is carried out by modulating the machine stator or rotor currents at a high frequency through a power converter or inverter. The high frequency modulation of the magnetic field can reduce the size of the machine.

Abstract: A three-phase AC solid-state transformer is provided which comprises three DC-DC converters. Each of the DC-DC converters has an internal transformer for galvanic isolation between its input and output sides. Each of the DC-DC converters has unipolar voltage across its input terminals and unipolar voltage across its output terminals. In one embodiment, the positive input terminals of the three DC-DC converters serve respectively as the three AC input terminals of the solid-state transformer and their positive output terminals provide the three phase AC output of the solid-state transformer. The negative input terminals of the three DC-DC converters are connected together to form a first common node, while the negative output terminals are connected together to form a second common node. The first common node has a voltage offset from the neutral of the input AC phases; and the second common node has a voltage offset from the neutral of the output AC phases.

Abstract: A transformer having an insulation system is presented. The transformer includes a magnetic core having an opening. Also, the transformer includes a plurality of primary windings disposed extending through the opening of the magnetic core. Further, the insulation system includes a first insulation substantially encapsulating the plurality of primary windings and impregnating spaces between the plurality of primary windings, and a second insulation disposed around the first insulation, where the second insulation has at least one of a predetermined dielectric strength and a predetermined thickness configured to isolate a first voltage signal in the plurality of primary windings from the magnetic core.

Abstract: A transformer having an insulation system is presented. The transformer includes a magnetic core having an opening. Also, the transformer includes a plurality of primary windings disposed extending through the opening of the magnetic core. Further, the insulation system includes a first insulation substantially encapsulating the plurality of primary windings and impregnating spaces between the plurality of primary windings, and a second insulation disposed around the first insulation, where the second insulation has at least one of a predetermined dielectric strength and a predetermined thickness configured to isolate a first voltage signal in the plurality of primary windings from the magnetic core.

Abstract: A power converter for coupling an electrical machine to an electrical grid includes a machine side converter and a grid side converter, each, side having a plurality of corresponding stages for converting a three-phase electrical signal of the electrical machine to a three-phase electrical signal of the electrical grid. The machine side converter includes a plurality of single-phase bridges coupled in series. The grid side converter includes a plurality of three-phase bridges. Each three-phase bridge corresponds to one of the single-phase bridges of the machine side converter. Each three-phase bridge is coupled to the primary windings of a corresponding transformer. The secondary windings of each corresponding transformer is phase-shifted from its primary windings and is coupled to secondary windings of another respective transformer, thus providing for coupling of the three-phase bridges in a series.

Abstract: A power converter for coupling an electrical machine to an electrical grid, the power converter including a machine side converter and a grid side converter, each side having a plurality of corresponding stages for converting a three-phase electrical signal of the electrical machine to a three-phase electrical signal of the electrical grid; wherein the machine side converter includes a plurality of single-phase bridges coupled in a series and has at least one coupling for coupling with the electrical machine; wherein the grid side converter includes a plurality of three-phase bridges, each three-phase bridge corresponding to one of the single-phase bridges of the machine side converter; wherein each three-phase bridge is coupled to the primary windings of a respective transformer while the secondary windings of the respective transformer are phase-shifted from the primary windings thereof and are coupled to secondary windings of another respective transformer, thus providing for coupling of the plurality of t

Abstract: Methods and apparatus for converting power from a power source are described. In one example embodiment, the method includes controlling multiple transformer and switchgear units coupled to a power source, and controlling multiple converter units connected in parallel. Each converter unit is coupled to a respective one of the transformer and switchgear units to form an individual thread. The transformer and switchgear unit and power converters are controlled so that the carrier waveforms for each individual thread are interleaved between each other over a carrier cycle.

Abstract: A power converter system for supplying an output voltage is provided. The power converter system is adapted to operate in a normal mode and a fault mode. The system comprises a plurality of bridges and a plurality of transformers. The system further comprises a plurality of dc link capacitors, each coupled across a corresponding bridge. The system also includes a controller adapted for, during the normal mode, switching each bridge with a respective normal phase shift. During the fault mode, the controller is adapted for switching each of the remaining ones of the bridges with a respective adjusted phase shift to generate the output voltage. During the fault mode, at least one of the plurality of bridges is bypassed.

Abstract: An active power quality conditioner for compensating reactive power and harmonic distortion in power systems. A pulse width modulated (PWM) inverter (70) for each phase is controlled to produce a harmonic distortion compensation signal that is coupled to an inductor. The inductor is connected in series between a stepped-wave inverter (84) and one phase of the power line. A current produced by the stepped-wave inverter compensates for the reactance of a load coupled to the power line. The PWM inverter operates at a frequency that is substantially greater than the fundamental frequency of the power line and is not exposed to the full power line voltage; it can be constructed using components of relatively low power and voltage rating. In contrast, the stepped-wave inverter, which is decoupled from the PWM inverter, operates at the fundamental frequency and is subjected to most of the stress. Both shunt coupled and series coupled compensators are described.