simple_series_hybrid.py

class openconcept.propulsion.systems.simple_series_hybrid.TwinSeriesHybridElectricPropulsionSystem(**kwargs)

Bases: Group

This is an example model of a series-hybrid propulsion system. One motor draws electrical load from two sources in a fractional split| a battery pack, and a turbogenerator setup. The control inputs are the power split fraction and the motor throttle setting; the turboshaft throttle matches the power level necessary to drive the generator at the required power level.

Fuel flows and prop thrust should be fairly accurate. Heat constraints haven’t yet been incorporated.

The “pilot” controls thrust by varying the motor throttles from 0 to 100+% of rated power. She may also vary the percentage of battery versus fuel being used by varying the power_split_fraction

This module alone cannot produce accurate fuel flows, battery loads, etc. You must do the following, either with an implicit solver or with the optimizer: - Set eng1.throttle such that gen1.elec_power_out = hybrid_split.power_out_A

The battery does not track its own state of charge (SOC); it is connected to elec_load simply so that the discharge rate can be compared to the discharge rate capability of the battery. SOC and fuel flows should be time-integrated at a higher level (in the mission analysis codes)

Arrows show flow of information. In openConcept, mechanical power operates on a ‘push’ basis, while electrical load operates on a ‘pull’ basis. We reconcile these flows across an implicit gap by driving a residual to 0 using a solver.

eng1.throttle                                                           hybrid_split.power_split_fraction           motor1.throttle
    ||                                                                                   ||                             ||
eng1 --shaft_power_out--> gen1 --elec_power_out--> {IMPLICIT GAP} <--power_out_B         ||           <--elec_load-- motor1 --shaft_power_out --> prop1 -->thrust
    ||                                                                             hybrid_split <--elec_load  ++
    ||                                            batt1.elec_load <--power_out_A                       <--elec_load-- motor2 --shaft_power_out --> prop2 -->thrust
    V                                                                   V                                              ||
fuel_flow (integrate over time)                                   elec_load (integrate over time to obtain SOC)       motor2.throttle
class openconcept.propulsion.systems.simple_series_hybrid.SeriesHybridElectricPropulsionSystem(**kwargs)

Bases: Group

This is an example model of a series-hybrid propulsion system. One motor draws electrical load from two sources in a fractional split| a battery pack, and a turbogenerator setup. The control inputs are the power split fraction and the motor throttle setting; the turboshaft throttle matches the power level necessary to drive the generator at the required power level. Fuel flows and prop thrust should be fairly accurate. Heat constraints have not yet been incorporated.

class openconcept.propulsion.systems.simple_series_hybrid.SingleSeriesHybridElectricPropulsionSystem(**kwargs)

Bases: Group

This is an example model of a series-hybrid propulsion system. One motor draws electrical load from two sources in a fractional split| a battery pack, and a turbogenerator setup. The control inputs are the power split fraction and the motor throttle setting; the turboshaft throttle matches the power level necessary to drive the generator at the required power level.

Fuel flows and prop thrust should be fairly accurate. Heat constraints haven’t yet been incorporated.

The “pilot” controls thrust by varying the motor throttles from 0 to 100+% of rated power. She may also vary the percentage of battery versus fuel being used by varying the power_split_fraction.

This module alone cannot produce accurate fuel flows, battery loads, etc. You must do the following, either with an implicit solver or with the optimizer: - Set eng1.throttle such that gen1.elec_power_out = hybrid_split.power_out_A

The battery does not track its own state of charge (SOC); it is connected to elec_load simply so that the discharge rate can be compared to the discharge rate capability of the battery. SOC and fuel flows should be time-integrated at a higher level (in the mission analysis codes).

Inputs:

  • ac|propulsion|engine|rating (float) – Turboshaft range extender power rating (scalar, kW)

  • ac|propulsion|propeller|diameter (float) – Propeller diameter (scalar, m)

  • ac|propulsion|motor|rating (float) – Motor power rating (scalar, kW)

  • ac|propulsion|generator|rating (float) – Range extender elec gen rating (scalar, kW)

  • ac|weights|W_battery (float) – Battery weight (scalar, kg)

  • TODO list all the control inputs

Outputs:

  • thrust (float) – Propulsion system total thrust (vector, N)

  • fuel_flow (float) – Fuel flow consumed by the turboshaft (vector, kg/s)

Options:

  • num_nodes (float) – Number of analysis points to run (default 1)

  • specific_energy (float) – Battery specific energy (default 300 Wh/kg)