An example hybrid aircraft propulsion system includes one or more parallel propulsion units, each of the parallel propulsion units comprising: a first propulsor; a gas turbine engine configured to drive the first propulsor; and an electrical machine selectively configurable to: generate, for output via one or more electrical busses, electrical energy using mechanical energy derived from the first propulsor or the gas turbine engine; and drive the first propulsor using electrical energy received via the one or more electrical busses; and one or more series propulsion units, each of the series propulsion units comprising: a second propulsor; and an electrical machine selectively configurable to: generate, for output via the one or more electrical busses, electrical energy using mechanical energy derived from the second propulsor or the gas turbine engine; and drive the second propulsor using electrical energy received from one or more electrical busses.

Methods and systems for controlling windmilling in an engine are described. An electric starter motor is coupled to the engine, a circuit element is coupled to the electric starter engine and to a DC signal source, and a control system coupled to the engine and to the circuit element. The control system is configured for: determining whether the engine is in a windmilling state; when the engine is in a windmilling state, commanding the circuit element to apply a DC signal to the electric starter motor; and modulating the DC signal applied to the electric starter motor to control a level of rotational motion of the engine.

An example hybrid aircraft propulsion system includes one or more power units configured to output electrical energy onto one or more electrical busses; a plurality of propulsors; and a plurality of electrical machines, each respective electrical machine configured to drive a respective propulsor of the plurality of propulsors using electrical energy received from at least one of the one or more electrical busses.

Systems and methods associated with electrical systems of aircraft are disclosed. A method disclosed herein comprises generating electricity using an electric generator operatively coupled to an engine of the aircraft, supplying the electricity generated using the electric generator to a baseline power bus; generating electricity using an electric starter generator operatively coupled to the engine; and supplying the electricity generated using the electric starter generator to a supplemental power bus independent from the baseline power bus.

Provided is a method for controlling a wind power installation. The wind power installation includes a generator for generating a generator current with one or more generator current phases, and an active rectifier for rectifying and controlling the generator current. For each generator current phase the rectifier has a plurality of controllable sub-rectifiers. Each controllable sub-rectifier is characterized by a partial inductance, each controllable sub-rectifier controls a partial current of the generator current phase and each generator current phase forms a summation current as a sum of all the partial currents of the relevant generator current phase. The active rectifier is controlled so that for each generator current phase the summation current is detected and each controllable sub-rectifier of the relevant current phase controls the partial current thereof depending on the detected summation current.

Systems and methods associated with electrical systems of aircraft are disclosed. A method disclosed herein comprises generating electricity using an electric generator operatively coupled to an engine of the aircraft, supplying the electricity generated using the electric generator to a baseline power bus; generating electricity using an electric starter generator operatively coupled to the engine; and supplying the electricity generated using the electric starter generator to a supplemental power bus independent from the baseline power bus.

A system includes a gas turbine operational at a constant rated rotational speed, a speed sensor to measure an actual speed of the gas turbine, a turbine controller to control the gas turbine to the constant rated rotational speed, and a generator coupled with the gas turbine and rotatable to output electric power. The system also includes a DC to DC converter to output a load current on a load bus to supply a load. The DC to DC converter is supplied input electric power from the generator. The system also includes an energy storage device cooperative operable with the DC to DC converter to supply power on the load bus, and a controller to receive the actual speed and adjust an output electrical current set point of the DC to DC converter to compensate for deviation of the actual speed from the constant rated speed of the gas turbine.

An electric generator assembly for an aircraft is provided. The electric generator assembly includes: a main generator having a main rotor and a main stator, the main stator comprising a first three-phase winding and a second three-phase winding, the first and second three-phase windings each configured to have a voltage induced therein by the main rotor, the first three-phase winding defining a phase shift from the second three-phase winding greater than zero degrees

A hybrid power system, includes at least one first isolation transformer having an input configured to be connectable to an output of a power supply; an energy storage system having at least one energy storage device and a power conversion system having at least one DC-to-AC converter connected to the at least one energy storage device; and at least one second isolation transformer configured as a step-up isolation transformer having an input connected to an output of the storage system.

Power recovery turbines can be used debottlenecking of an existing plant, as well as recover electric power when revamping a plant. A process for recovering energy in a petroleum, petrochemical, or chemical plant is described. A fluid stream having a first control valve thereon is identified. A first power-recovery turbine is installed at the location of the first control valve, and at least a portion of the first fluid stream is directed through the first power-recovery turbine to generate electric power as direct current therefrom. The electric power is then recovered.