Abstract: Methods and systems are provided to damp oscillations in a synchronous alternating current (AC) grid. Current may be received from the synchronous AC grid through a phase of an n-phase supply line. The current received from the synchronous AC grid is supplied to a phase of the synchronous motor. A sub-harmonic oscillation may be detected in the current received from the synchronous AC grid. The sub-harmonic oscillation may be damped by: shunting a portion of the current away from the phase of the synchronous motor during a first time period in an upper-half of the sub-harmonic oscillation, and/or supplying compensation current from a partial power converter to the phase of the synchronous motor during a second time period in a lower-half of the sub-harmonic oscillation.

Abstract: Methods and systems are provided to damp oscillations in a synchronous alternating current (AC) grid. Current may be received from the synchronous AC grid through a phase of an n-phase supply line. The current received from the synchronous AC grid is supplied to a phase of the synchronous motor. A sub-harmonic oscillation may be detected in the current received from the synchronous AC grid. The sub-harmonic oscillation may be damped by: shunting a portion of the current away from the phase of the synchronous motor during a first time period in an upper-half of the sub-harmonic oscillation, and/or supplying compensation current from a partial power converter to the phase of the synchronous motor during a second time period in a lower-half of the sub-harmonic oscillation.

Abstract: A power system includes a bus, a first controller and one or more second controllers. The first controller is configured to excite a first generator to generate electric power on the bus in response to initiation of rotation of the first generator. The one or more second controllers are configured to excite one or more respective second generators with a constant excitation in response to initiation of rotation of the first generator. The second generator(s) are electrically coupled with the bus and configured to operate as a motor to commence synchronous rotation with the first generator in response to electric power being present on the bus. The second controller(s) are further configured to initiate dynamic adjustment of the excitation of the second generator(s) to generate electric power on the bus with the second generator(s) in response to the first generator and the second generator(s) synchronously reaching a predetermined rotational speed.

Abstract: A system may include a prime mover configured to provide mechanical energy to the system by spinning a shaft. The system further includes a synchronous AC generator mechanically coupled to the shaft, and an exciter mechanically coupled to the shaft and configured to output a field current for exciting the synchronous AC generator. The system also includes a number of synchronous electric motors electrically coupled to the AC generator and configured to drive one or more mechanical loads. A controller of the system is configured to establish and maintain a magnetic coupling between the synchronous AC generator and the synchronous electric motors by controlling a level of the field current during a ramped increase in rotation of the synchronous AC generator from zero rotational speed. The motors accelerate synchronously with the generator due to the magnetic coupling as the rotational speed of the generator increases.

Abstract: A system includes a synchronous generator coupled to an excitation system. The excitation system may output an excitation signal to excite the synchronous generator to produce a voltage and a current at an output of the synchronous generator. During startup, when the synchronous generator is rotating at less than rated speed, non-rotating synchronous electric motors may be electrically coupled to the synchronous generator. A controller may direct the excitation system to output the excitation signal to generate, with the synchronous generator, a first magnitude of current flow, and the synchronous motor loads are non-rotational in response to receipt of the first magnitude of current flow. In addition, the controller may selectively direct output of a pulse of the excitation signal, when the synchronous generator is rotating at less than rated speed, to urge the non-rotating synchronous motor loads into rotational electrical alignment with the synchronous generator and each other.

Abstract: Systems and methods thermal management of a directed energy weapon are provided. The system may include a controller module executable by a processor to determine a planned energy emission from a light-emitting diode (LED) of the directed energy weapon. The controller module may generate a cooling instruction to influence a temperature of the LED with a cooling fluid in response to the planned energy emission. The controller module may cause the cooling fluid to be applied to the LED in accordance with the cooling instruction prior to a start of the planned energy emission of the LED.

Abstract: A system includes one or more synchronous generators mechanically coupled to an excitation system. The excitation system is configured to output an excitation signal to excite the synchronous generator to produce a voltage and a current at an output of the synchronous generator. During startup of the synchronous generator, the excitation system may also output pulses of the excitation signal to initiate synchronism of one or more non-rotating electric motors electrically coupled to the synchronous generator. In addition, the pulses may be output to urge rotation of the non-rotating electric motors into rotational electrical alignment with the synchronous generator and each other.

Abstract: A propulsion system is described that includes an AC generator configured to produce AC current, and a plurality of propulsors configured to receive the AC current from the AC generator and provide thrust based on the AC current from the AC generator. The propulsion system further includes an AC distribution system configured to deliver a first portion of the AC current to a first group of propulsors from the plurality of propulsors, and a second subsystem configured to deliver a second portion of the AC current to a second group of propulsors from the plurality of propulsors.

Abstract: Systems and methods for pre-aligning rotors of synchronous motors on a synchronous AC grid prior to startup of the motors are provided. A partial power converter may provide an alignment current through an n-phase supply line to a synchronous AC motor. The synchronous AC motor may be configured to receive polyphase AC power through the n-phase supply line from the synchronous AC grid, whereas the partial power converter is powered by a power source isolated from the synchronous AC grid. The alignment current may cause a rotor of the synchronous AC motor to move to and stop at a target angular position.

Abstract: Methods and systems are provided to damp oscillations in a synchronous alternating current (AC) grid. Current may be received from the synchronous AC grid through a phase of an n-phase supply line. The current received from the synchronous AC grid is supplied to a phase of the synchronous motor. A sub-harmonic oscillation may be detected in the current received from the synchronous AC grid. The sub-harmonic oscillation may be damped by: shunting a portion of the current away from the phase of the synchronous motor during a first time period in an upper-half of the sub-harmonic oscillation, and/or supplying compensation current from a partial power converter to the phase of the synchronous motor during a second time period in a lower-half of the sub-harmonic oscillation.

Abstract: Systems and methods for pre-aligning rotors of synchronous motors on a synchronous AC grid prior to startup of the motors are provided. A partial power converter may provide an alignment current through an n-phase supply line to a synchronous AC motor. The synchronous AC motor may be configured to receive polyphase AC power through the n-phase supply line from the synchronous AC grid, whereas the partial power converter is powered by a power source isolated from the synchronous AC grid. The alignment current may cause a rotor of the synchronous AC motor to move to and stop at a target angular position.

Abstract: Methods and systems for load alignment assistance are provided. An alignment current may be provided with a partial power converter through an n-phase supply line to a synchronous alternating current (AC) motor during a startup of a synchronous AC grid. The synchronous AC motor may receive polyphase AC power through the n-phase supply line from the synchronous AC grid during the startup. The partial power converter may be powered by a power source isolated from the synchronous AC grid. The alignment current may be controlled such that the alignment current causes a rotor of the synchronous AC motor to align with a rotor of a generator that powers the synchronous AC grid.

Abstract: An electric propulsion system is described that includes an AC drive circuit, a synchronization circuit, and a control unit. The AC drive circuit includes a plurality of propulsor motors, an AC power bus, and an AC generator that delivers AC electrical power to the AC power bus for simultaneously driving the plurality of propulsor motors. The synchronization circuit is configured to synchronize, with the AC generator, single propulsor motor from the plurality of propulsor motors, at a time. The control unit is configured to maintain synchronicity between the single propulsor motor and the AC generator by engaging the synchronization circuit with the single propulsor motor in response to determining that the single propulsor motor is not synchronized with the AC generator.

Abstract: A propulsion system is described that includes an electrical bus, a generator configured to provide electrical power to the electrical bus, a plurality of propulsory configured to provide thrust by simultaneously being driven by the electrical power at the electrical bus, and a controller. The controller is configured to synchronize a rotational speed of an individual propulsor from the plurality of propulsory with a rotational speed of the generator after the individual propulsor has become unsynchronized with the rotational speed of the generator by controlling at least one of the rotational speed of the generator, nozzle area of the individual propulsor, or a pitch angle of the individual propulsor.

Abstract: A system includes one or more synchronous generators mechanically coupled to an excitation system. The excitation system is configured to output an excitation signal to excite the synchronous generator to produce a voltage and a current at an output of the synchronous generator. During startup of the synchronous generator, the excitation system may also output pulses of the excitation signal to initiate synchronism of one or more non-rotating electric motors electrically coupled to the synchronous generator. In addition, the pulses may be output to urge rotation of the non-rotating electric motors into rotational electrical alignment with the synchronous generator and each other.

Abstract: A system may include a prime mover configured to provide mechanical energy to the system by spinning a shaft. The system further includes a synchronous AC generator mechanically coupled to the shaft, and an exciter mechanically coupled to the shaft and configured to output a field current for exciting the synchronous AC generator. The system also includes a number of synchronous electric motors electrically coupled to the AC generator and configured to drive one or more mechanical loads. A controller of the system is configured to establish and maintain a magnetic coupling between the synchronous AC generator and the synchronous electric motors by controlling a level of the field current during a ramped increase in rotation of the synchronous AC generator from zero rotational speed. The motors accelerate synchronously with the generator due to the magnetic coupling as the rotational speed of the generator increases.

Abstract: A system includes one or more synchronous generators and one or more corresponding exciters. The exciter is configured to output a field current for exciting the synchronous generator to produce a voltage and a current at an output of the synchronous generator. The system may also include one or more electric motors electrically coupled to the synchronous generator and configured to drive one or more mechanical loads. A controller included in the system is configured to identify power angle oscillations between the voltage and the current and control an exciter voltage of the exciter to damp the identified power angle oscillations.

Abstract: A system includes an exciter configured to operate with a synchronous generator. The exciter may be mechanically coupled and rotatable with the synchronous generator, or the exciter may be independently rotatable. The exciter is configured to output a field current for exciting the synchronous generator to produce a voltage and a current at an output of the synchronous generator. The synchronous generator may be synchronized with loads during a time when the synchronous generator is at substantially zero speed and the loads, such as motors, are at zero speed. A controller included in the system is configured to control output of the field current by the exciter with an exciter voltage. The controller may control the exciter voltage to selective include an AC component and DC component in accordance with a rotational speed of the exciter.

Abstract: A power system includes a bus, a first controller and one or more second controllers. The first controller is configured to excite a first generator to generate electric power on the bus in response to initiation of rotation of the first generator. The one or more second controllers are configured to excite one or more respective second generators with a constant excitation in response to initiation of rotation of the first generator. The second generator(s) are electrically coupled with the bus and configured to operate as a motor to commence synchronous rotation with the first generator in response to electric power being present on the bus. The second controller(s) are further configured to initiate dynamic adjustment of the excitation of the second generator(s) to generate electric power on the bus with the second generator(s) in response to the first generator and the second generator(s) synchronously reaching a predetermined rotational speed.

Abstract: An alternating current type electric propulsion system is described that includes an AC generator and a plurality of propulsors electrically coupled to the AC generator. A first propulsor from the plurality of propulsors includes a first motor that drives a first fan of the first propulsor at a first speed. A second propulsor from the plurality of propulsors comprises a second motor that drives a second fan of the second propulsor at a second speed that is different than the first speed.