Systems and methods for implementing lightweight and reliable hybrid or electric powertrains for aircraft

A method for controlling power flow in a hybrid electric powertrain, the hybrid electric powertrain comprising an AC generation system including a generator and a rectifier unit, coupled to an HVDC bus and an HVDC battery coupled to the HVDC bus, the method comprising:

• monitoring a current flowing from or to the HVDC battery;
• determining, via a system controller, a target HVDC bus voltage sufficient to modify the monitored current toward a desired battery current level, wherein the desired battery current level is based, at least in part, on a safe operating limit of the HVDC battery;
• transmitting a control signal representing the target HVDC bus voltage to the AC generation system;
• and
• controlling the AC generation system, in response to the control signal, to adjust a voltage of the HVDC bus relative to a voltage of the HVDC battery, thereby controlling the current flowing from or to the HVDC battery.

A hybrid electric powertrain system for an aircraft, comprising:

• a permanent magnet (PM) generator;
• an HVDC battery;
• an active rectifier unit coupling the PM generator to an HVDC bus shared with the HVDC battery;
• and
• a system controller configured to:
• receive a command indicating a desired power split between the PM generator and the HVDC battery;
• determine an output current requirement for the active rectifier unit based, at least in part, on the desired power split;
• and
• control switching modes of the active rectifier unit to regulate an output current of the active rectifier unit to match the output current requirement;
• wherein a proportion of power delivered by the PM generator relative to the HVDC battery is controlled by regulation of the output current of the active rectifier unit.