A hybrid electric aircraft propulsion system and method of operation are described. The system comprises a thermal engine, a generator coupled to the thermal engine, a first electric propulsor operatively connected to the generator to receive alternating current (AC) electric power therefrom, a second electric propulsor, a generator inverter operatively connected to the generator to convert AC electric power to direct current (DC) electric power, and a first motor inverter operatively connected to the generator inverter and selectively connected to one of the first electric propulsor and the second electric propulsor and configured to receive the DC electric power and provide the first electric propulsor and the second electric propulsor with AC electric power, respectively.

A hybrid drive train for a self propelled power trowel includes a frame having a centerline from front to rear, an engine-generator set, a pair of rotors with trowel blades tiltably connected to the frame and positioned to support the frame above a concrete surface being finished, electric motors for driving the rotors, means for tilting each rotor toward and away from the centerline, and means for tilting a rotor fore and aft, parallel to the centerline. A rectifier and inverter in series at the engine-generator output allows engine speed to be regulated by a capacitor bank, and usage of highly efficient brushless AC synchronous motors to drive the rotors. A rechargeable battery may be connected in parallel with the capacitor bank.

A hybrid drive train for a self propelled power trowel includes a frame having a centerline from front to rear, an engine-generator set, a pair of rotors with trowel blades tiltably connected to the frame and positioned to support the frame above a concrete surface being finished, electric motors for driving the rotors, means for tilting each rotor toward and away from the centerline, and means for tilting a rotor fore and aft, parallel to the centerline. A rectifier and inverter in series at the engine-generator output allows engine speed to be regulated by a capacitor bank, and usage of highly efficient brushless AC synchronous motors to drive the rotors. A rechargeable battery may be connected in parallel with the capacitor bank.

A method of operating a hybrid electric vehicle includes driving an engine to generate mechanical energy, converting the mechanical energy into a first AC voltage, estimating a total DC link current associated with a respective plurality of loads of the hybrid electric vehicle, converting, with a first inverter, the first AC voltage into a DC bus voltage by regulating the DC bus voltage based on the total DC link current, and inverting, with a respective plurality of inverters, the DC bus voltage into a respective plurality of other AC voltages to drive the respective plurality of loads on the hybrid electric vehicle.

An aspect includes a battery charging system for a hybrid electric aircraft. The battery charging system includes a generator, a battery system, and a controller. The controller is operable to charge the battery system up to a first charge level based on receiving a first charging current at a power input. An operational status of a gas turbine engine of the hybrid electric aircraft is monitored. The battery system is charged at a second charging current received from the generator driven by the gas turbine engine responsive to determining that the gas turbine engine is in a taxi state, where the second charging current is less than the first charging current. Charging of the battery system is halted based on detecting a transition of the gas turbine engine from the taxi state to an off-idle throttle state.

A system for providing mechanical and electrical power in a vehicle or other engine-driven platform includes a first engine having a first power rating and a second engine having a second power rating that is less than the first power rating. The system further includes a first generator (for example, an alternator) for generating electrical power for a load operation (such as vehicle propulsion), and a second generator (for example, a DFIG) for generating fixed frequency electrical power; both generators are operatively connected to and powered by the first and/or second engines. The first and/or second engines may be selected to power the first generator for generating power for vehicle propulsion or another load operation depending upon situational power requirements of the engine-driven platform.

An electric drive vehicle provided with a current collecting device, the current collecting device including: a framework having an underframe, a lower frame that is pivotably linked to the underframe, and an upper frame that is pivotably linked to the lower frame; a current collecting portion that is supported by the upper frame; and a lock mechanism that holds the framework in a predetermined posture, in which the framework is capable of moving up and down between a standing posture in which the current collecting portion is ascended and a folded posture in which the current collecting portion is descended, and the lock mechanism includes an adsorption plate made of a magnetic material provided in the upper frame, and a hook device which is equipped with an electromagnet and adsorbs to hold the adsorption plate by a magnetic force to hold the framework in the folded posture.

A vehicle includes primary and secondary axles including primary and secondary electric machines, respectively. A vehicle controller is programmed to, responsive to a braking torque request, command regenerative torques, that are a proportion of the braking torque request, to the electric machines such that the proportion commanded to the secondary electric machine decreases responsive to lateral acceleration of the vehicle increasing.

A vehicle includes primary and secondary axles including primary and secondary electric machines, respectively. A vehicle controller is programmed to, responsive to a braking torque request, command regenerative torques, that are a proportion of the braking torque request, to the electric machines such that the proportion commanded to the secondary electric machine decreases responsive to lateral acceleration of the vehicle increasing.

An AC electrical system for a vehicle and methods of operating the same are provided. In one aspect, an AC electrical system includes a first electric machine mechanically coupled with a first spool of a gas turbine engine and a second electric machine mechanically coupled with a second spool of the gas turbine engine. The system also includes a first AC bus and a second AC bus. A first electrical channel electrically couples the first electric machine to the first AC bus and a second electrical channel electrically couples the second electric machine to the second AC bus. The system also includes one or more connection links and one or more power converters for selectively electrically coupling the first and second electrical channels so that electrical power generated by one electric machine can be converted and shared with the other electric machine and electrical loads of the other channel.