Provided are gearboxes including compound planet gear assemblies as well as methods of using such gearboxes. A gearbox includes at least a first ring gear and a second ring gear. Depending on the current gear selection, one of these ring gears may be engaged with a shifting mechanism or not engaged with any ring gears when in a neutral gear. The first ring gear may be constantly engaged with a first planet gear of a compound planet gear assembly, while the second ring gear may be constantly engaged with a second planet gear of the same compound planet gear assembly. The first planet gear may be also engaged with a sun gear coupled to a shaft. Another shaft is coupled to the shifting mechanism. Different gear selections of the gearbox engage different ring gears to the shifting mechanism thereby changing the rotational speed ratio of the two shafts.

An electrical gear configured to supply electrical drive power to a machinery to be rotated at high speed, such as a subsea motor/pump or a subsea motor/compressor assembly, the electrical gear including a high input voltage AC-motor having a low pole number, the AC-motor drivingly connected to a medium output voltage AC-generator having inverted design, wherein in the AC-generator the field windings are supported on a rotor which is journalled for rotation inside an outer stator carrying a high number of magnet poles, the AC-motor is configured to run on high voltage alternating current at a first frequency, and the AC-generator is configured to deliver medium voltage alternating current at a second frequency, higher than said first frequency, to an AC-motor to be energized having a low pole number.

An electrical gear configured to supply electrical drive power to a machinery to be rotated at high speed, such as a subsea motor/pump or a subsea motor/compressor assembly, the electrical gear including a high input voltage AC-motor having a low pole number, the AC-motor drivingly connected to a medium output voltage AC-generator having inverted design, wherein in the AC-generator the field windings are supported on a rotor which is journalled for rotation inside an outer stator carrying a high number of magnet poles, the AC-motor is configured to run on high voltage alternating current at a first frequency, and the AC-generator is configured to deliver medium voltage alternating current at a second frequency, higher than said first frequency, to an AC-motor to be energized having a low pole number.

An electrical drive machine for a vehicle includes a brake apparatus and a gear-selection apparatus, such that the electrical machine is designed as a current-powered synchronous machine. The vehicle includes a control unit which is associated with the current-powered synchronous machine, wherein the control unit sets a field current of the rotor based on a gear-selection position set at the gear-selection apparatus and based on a position of a brake pedal of the brake apparatus.

There is provided a hybrid electric aircraft propulsion system and method for operating same. The method comprises providing, to a first electric motor and a second electric motor, alternating current (AC) electric power from a generator, the generator receiving rotational power from a thermal engine, providing, to the first electric motor and the second electric motor, AC electric power from at least one motor inverter, the at least one motor inverter configured to convert DC electric power from a DC power source into AC electric power, and selectively driving the first and second electric motors from the generator, the at least one motor inverter, or a combination thereof, wherein the first electric motor drives a first rotating propulsor and the second electric motor drives a second rotating propulsor.

There is provided a hybrid electric aircraft propulsion system and method for operating same. The method comprises providing, to a first electric motor and a second electric motor, alternating current (AC) electric power from a generator, the generator receiving rotational power from a thermal engine, providing, to the first electric motor and the second electric motor, AC electric power from at least one motor inverter, the at least one motor inverter configured to convert DC electric power from a DC power source into AC electric power, and selectively driving the first and second electric motors from the generator, the at least one motor inverter, or a combination thereof, wherein the first electric motor drives a first rotating propulsor and the second electric motor drives a second rotating propulsor.