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.

A compressed air turbine DC power generator system, comprising: an aerodynamic turbine engine; a direct current generator (2) used for generating a direct current by using power output of the aerodynamic turbine engine as a driving input; and a control unit (3) used for controlling the rotating speed of the aerodynamic turbine engine to generate the power output and adjusting the output current and/or the output voltage of the direct current generator (2). The compressed air turbine DC power generator system is miniaturized and has high integration level, effectively overcomes the disadvantages such as low power density and great vibration noise of a power generation system with an internal combustion engine, and has a high industrial application value. The compressed air turbine DC power generator system can be used as an auxiliary power supply in the development process of an electric automobile, thereby effectively resolving the problem of range anxiety of a pure electric automobile.

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

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.

A power generation system includes an electric generator mechanically driven by a variable speed kinetic source, a first power conversion system connected with an output of the electric generator, and a second power conversion system connected with the output of the electric generator, wherein the electric generator and power conversion systems are adapted to convert the output of the electric generator to a predetermined direct current (DC) voltage.

A compressed air turbine DC power generator system, comprising: an aerodynamic turbine engine; a direct current generator (2) used for generating a direct current by using power output of the aerodynamic turbine engine as a driving input; and a control unit (3) used for controlling the rotating speed of the aerodynamic turbine engine to generate the power output and adjusting the output current and/or the output voltage of the direct current generator (2). The compressed air turbine DC power generator system is miniaturized and has high integration level, effectively overcomes the disadvantages such as low power density and great vibration noise of a power generation system with an internal combustion engine, and has a high industrial application value. The compressed air turbine DC power generator system can be used as an auxiliary power supply in the development process of an electric automobile, thereby effectively resolving the problem of range anxiety of a pure electric automobile.

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.

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.

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