Abstract: In one embodiment, a stator coil that includes a first turn with two or more strands is provided. The first turn includes first and second opposite sides, a coil termination at a first end of the first turn and an inversion region disposed at a second end, opposite the coil termination. The stator coil also includes at least one additional turn with two or more strands. The at least one additional turn includes first and second opposite sides, and an inversion region located adjacent to the inversion region of the first turn. The first and second sides of the first turn are inverted relative to the first and second sides of the at least one additional turn outside their respective inversion regions.

Abstract: A manifold for cooling the end turns of stator coils of a generator is provided. The manifold includes a ring having a surface with a plurality of spray nozzles formed integral with the ring and extending from the surface. Each spray nozzle of the plurality of spray nozzles includes a channel having a diameter, and a surface having a selected width and an angle, wherein the channel and the surface are configured to spray oil on first end turns of the stator coils.

Abstract: Systems and methods for energy management of hybrid electrical systems are discussed herein. In certain embodiments, a system includes one or more generators configured to provide generator electric power. The system also includes one or more batteries configured to provide stored electric power. Further, the system includes one or more generator controllers using a state of charge for the one or more batteries, wherein the one or more generator controllers control a combination of the generator electric power and the stored electric power provided to one or more loads according to a plurality of modes, wherein multiple modes of the plurality of modes are based on one or more parameters of the one or more batteries.

Abstract: In one embodiment, a stator coil that includes a first turn with two or more strands is provided. The first turn includes first and second opposite sides, a coil termination at a first end of the first turn and an inversion region disposed at a second end, opposite the coil termination. The stator coil also includes at least one additional turn with two or more strands. The at least one additional turn includes first and second opposite sides, and an inversion region located adjacent to the inversion region of the first turn. The first and second sides of the first turn are inverted relative to the first and second sides of the at least one additional turn outside their respective inversion regions.

Abstract: A cooling sleeve for an electric machine is provided. The cooling sleeve includes: a cylindrical body having an exterior surface, a first channel formed in the cylindrical body and having a first inlet for receiving a cooling fluid, and a second channel formed in the cylindrical body and having a second inlet for receiving the cooling fluid. The first inlet and the second inlet are formed on the exterior surface at a center along a length of the cylindrical body. A plurality of turbulators are formed in the first channel and the second channel and a cylindrical cover is configured to be disposed over the cylindrical body.

Abstract: Systems and methods for voltage regulation of high voltage direct current systems are provided. In certain embodiments, a system includes a generator that generates alternating current (AC) voltage. The system further includes a power converter that converts the AC voltage into regulated direct current (DC) voltage. Also, the system includes a voltage regulator. In additional embodiments, the voltage regulator includes an AC voltage regulator that regulates the AC voltage generated by the generator. Also, the voltage regulator includes a DC voltage regulator that regulates the DC voltage produced by the power converter. Moreover, the voltage regulator includes a regulator selector that selectively activates one of the AC voltage regulator and the DC voltage regulator based on a current from the power converter and at least one of a voltage of the generator and a voltage of the power converter.

Abstract: Systems and methods for voltage regulation of high voltage direct current systems are provided. In certain embodiments, a system includes a generator that generates alternating current (AC) voltage. The system further includes a power converter that converts the AC voltage into regulated direct current (DC) voltage. Also, the system includes a voltage regulator. In additional embodiments, the voltage regulator includes an AC voltage regulator that regulates the AC voltage generated by the generator. Also, the voltage regulator includes a DC voltage regulator that regulates the DC voltage produced by the power converter. Moreover, the voltage regulator includes a regulator selector that selectively activates one of the AC voltage regulator and the DC voltage regulator based on a current from the power converter and at least one of a voltage of the generator and a voltage of the power converter.

Abstract: In one embodiment, a stator coil that includes a first turn with two or more strands is provided. The first turn includes first and second opposite sides, a coil termination at a first end of the first turn and an inversion region disposed at a second end, opposite the coil termination. The stator coil also includes at least one additional turn with two or more strands. The at least one additional turn includes first and second opposite sides, and an inversion region located adjacent to the inversion region of the first turn. The first and second sides of the first turn are inverted relative to the first and second sides of the at least one additional turn outside their respective inversion regions.

Abstract: Techniques for achieving a variety of selected direct current (DC) voltage outputs are disclosed. In one embodiment, a power generation system includes at least one multi-phase generator configured to generate an alternating current (AC) voltage. A plurality of diode rectifier circuits is coupled to the at least one multi-phase generator, which are configured to receive the AC voltage and convert the AC voltage to a DC voltage output. The power generation system includes configuration circuitry coupled to the plurality of diode rectifier circuits configured to configure the diode rectifier circuits in multiple configurations. For example, the configuration circuitry can configure the diode rectifier circuits in a series configuration to achieve a first DC voltage level, a parallel configuration to achieve a second DC voltage level, or a mixed series-parallel configuration to achieve a third DC voltage level.

Abstract: Techniques for achieving a constant narrow range DC voltage are disclosed. In an embodiment, a system comprises at least one variable speed, multi-phased generator configured to generate an alternating current (AC) voltage. A plurality of diode rectifier circuits is coupled to the at least one multi-phased generator. The plurality of diode rectifier circuits are configured to convert the AC voltage to a direct current (DC) voltage. A plurality of high-power DC contactors is connected to the plurality of diode rectifier circuits. The plurality of high-power DC contactors is configured to configure outputs of the plurality of diode rectifier circuits in one of a parallel, series, and/or mixed parallel and series configuration. A controller coupled to the plurality of diode rectifier circuits and is configured to reconfigure the plurality of high-power DC contactors based on a control parameter of the at least one multi-phased generator.

Abstract: In an example, a rotor for an electric machine includes a cylindrical central portion, and a plurality of poles extending from the cylindrical central portion in a radial direction. Each pole of the plurality of poles includes a top surface that includes one or more slots that are located in and extend across the top surface. The rotor further includes a plurality of stranded wire damper windings, wherein each stranded wire damper winding of the plurality of stranded wire damper windings includes two or more conductor wires twisted together and insulated from each other. The two or more conductor wires are twisted together five or more times, and each respective stranded wire damper winding of the plurality of stranded wire damper windings is positioned within a respective slot of the one or more slots of a respective pole of the plurality of poles.

Abstract: Techniques for achieving a constant narrow range DC voltage are disclosed. In an embodiment, a system comprises at least one variable speed, multi-phased generator configured to generate an alternating current (AC) voltage. A plurality of diode rectifier circuits is coupled to the at least one multi-phased generator. The plurality of diode rectifier circuits are configured to convert the AC voltage to a direct current (DC) voltage. A plurality of high-power DC contactors is connected to the plurality of diode rectifier circuits. The plurality of high-power DC contactors is configured to configure outputs of the plurality of diode rectifier circuits in one of a parallel, series, and/or mixed parallel and series configuration. A controller coupled to the plurality of diode rectifier circuits and is configured to reconfigure the plurality of high-power DC contactors based on a control parameter of the at least one multi-phased generator.

Abstract: Techniques for achieving a variety of selected direct current (DC) voltage outputs are disclosed. In one embodiment, a power generation system includes at least one multi-phase generator configured to generate an alternating current (AC) voltage. A plurality of diode rectifier circuits is coupled to the at least one multi-phase generator, which are configured to receive the AC voltage and convert the AC voltage to a DC voltage output. The power generation system includes configuration circuitry coupled to the plurality of diode rectifier circuits configured to configure the diode rectifier circuits in multiple configurations. For example, the configuration circuitry can configure the diode rectifier circuits in a series configuration to achieve a first DC voltage level, a parallel configuration to achieve a second DC voltage level, or a mixed series-parallel configuration to achieve a third DC voltage level.

Abstract: In one embodiment, a stator coil that includes a first turn with two or more strands is provided. The first turn includes first and second opposite sides, a coil termination at a first end of the first turn and an inversion region disposed at a second end, opposite the coil termination. The stator coil also includes at least one additional turn with two or more strands. The at least one additional turn includes first and second opposite sides, and an inversion region located adjacent to the inversion region of the first turn. The first and second sides of the first turn are inverted relative to the first and second sides of the at least one additional turn outside their respective inversion regions.

Abstract: A high voltage direct current (DC) tether for an airborne wind turbine has a reduced weight compared to conventional tethers. The weight reduction is achieved by using one conductor in the center of the feeder and the shielding of the feeder as a second conductor. A mechanical strength element is disposed in between the center conductor and the shielding. In this configuration, the mechanical strength element acts also as an insulator. The center conductor and the shielding can be made of aluminum or copper. The strength element can be a high strength fiber composite, woven such as VECTRAN® or SPECTRA®. The main weight savings are due to using the shielding for multiple purposes—as a conductor, as lightning protection and as an electromagnetic interference (EMI) effects barrier, while providing strength to the tether, and from using the mechanical strength element (VECTRAN® or SPECTRA®) as an insulator. The shielding is typically used as the return conductor.

Abstract: A synchronous electric machine operates as a starter-generator for an aircraft. When operating in a starting mode, a main stator of the machine is supplied with electrical power at a constant frequency. An exciter stator is supplied with variable frequency power. As rotational speed increases, the exciter variable frequency changes correspondingly to maintain synchronous operation of the machine and maximum torque. In a generator mode, variable frequency is applied to the exciter stator with the exciter frequency varying as a function of rotational speed of an engine driving the machine. This provides for a constant frequency output from the machine.

Abstract: A generator system is configured to supply two phase excitation current from an exciter rotor to a main generator rotor. When driven by a variable speed prime mover, the generator system provides relatively constant frequency AC power by independently controlling the main rotor flux rotational speed. The generator system includes an exciter stator that induces current in the exciter rotor windings at a desired frequency and phasing. The exciter rotor windings are electrically connected to the main rotor windings to provide two-phase excitation current to the main rotor windings. Excitation is supplied to the exciter stator from an exciter controller, which controls the frequency and phasing of the exciter excitation, based on the rotational speed of the generator, to maintain a constant output frequency.

Abstract: A generator system is configured to supply two phase excitation current from an exciter rotor to a main generator rotor. When driven by a variable speed prime mover, the generator system provides relatively constant frequency AC power by independently controlling the main rotor flux rotational speed. The generator system includes an exciter stator that induces current in the exciter rotor windings at a desired frequency and phasing. The exciter rotor windings are electrically connected to the main rotor windings to provide two-phase excitation current to the main rotor windings. Excitation is supplied to the exciter stator from an exciter controller, which controls the frequency and phasing of the exciter excitation, based on the rotational speed of the generator, to maintain a constant output frequency.

Abstract: A matrix converter circuit having two AC/AC matrix converters coupled in parallel in a first mode to power a starter and decoupled in a second mode to each power separate functions used in aircraft power applications. Three common functional modes include 1) start mode with two matrix converters operating in parallel powering the starter, 2) a motor mode where one matrix converter powers a motor, and 3) a constant frequency power mode where the other matrix converter provides constant frequency AC power.

Abstract: A generator system is configured to supply two phase excitation current from an exciter rotor to a main generator rotor. When driven by a variable speed prime mover, the generator system provides relatively constant frequency AC power by independently controlling the main rotor flux rotational speed. The generator system includes an exciter stator that induces current in the exciter rotor windings at a desired frequency and phasing. The exciter rotor windings are electrically connected to the main rotor windings to provide two-phase excitation current to the main rotor windings. Excitation is supplied to the exciter stator from an exciter controller, which controls the frequency and phasing of the exciter excitation, based on the rotational speed of the generator, to maintain a constant output frequency.