System and method for managing electric motor propulsion command limits on a hybrid rotorcraft
A method includes receiving a torque load demand associated with a rotor, and a gas-turbine engine (GTE) power measurement among first measurements from a GTE. The method includes determining whether the torque load demand is within operating limits of the GTE without assistance from a motor, based on the first measurements compared to a condition for operating in an assisted mode. The method includes generating a first command signal that sets a motor torque limit, and a second command signal that sets a motor speed reference value based on a difference between the torque load demand and the GTE power measurement. The method includes setting or reducing the motor torque limit to a low value when the condition for operating in the assisted mode is not satisfied, and increasing the motor torque limit to a high value when the condition for operating in the assisted mode is satisfied.
1 . A method comprising:
receiving a torque load demand associated with a rotor, and a gas-turbine engine (GTE) power measurement among first measurements from a GTE;
determining whether the torque load demand is within operating limits of the GTE without assistance from a motor, based on the first measurements compared to a condition for operating in an assisted mode; and
generating and outputting a first command signal that sets a motor torque limit, and a second command signal that sets a motor speed reference value based on a difference between the torque load demand and the GTE power measurement,
wherein generating the first and second command signals includes:
setting or reducing the motor torque limit to a low value and setting the motor speed reference value equal to a speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is not satisfied; and
increasing the motor torque limit to a high value and varying the motor speed reference value from the speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is satisfied.
2 . The method of claim 1 , further comprising:
determining that the condition for operating in the assisted mode is satisfied based on the torque load demand exceeding a steady-state operating limit of the engine or a rate of change of the torque load demand exceeding a transient operating limit of the engine.
3 . The method of claim 1 , further comprising:
determining that the condition for operating in the assisted mode is not satisfied based on:
the torque load demand not exceeding a steady-state operating limit of the engine; and
a rate of change of the torque load demand exceeding a transient operating limit of the engine.
4 . The method of claim 1 , wherein to generate the first command signal, reducing the motor torque limit to the low value comprises:
decrementing the motor torque limit from the high value to a medium value at an instantaneous rate; and
reducing the motor torque limit from the medium value to the low value at a non-instantaneous rate that is based on pre-defined rate limit.
5 . The method of claim 4 , further comprising:
determining, as the medium value, a motor torque measurement at a time of satisfying a condition in which a torque difference between the motor torque measurement and a GTE torque measurement is within a threshold.
6 . The method of claim 4 , further comprising:
determining, as the medium value, a motor torque measurement at a time of satisfying a condition in which an increase of the motor torque measurement stops.
7 . The method of claim 4 , further comprising:
determining, as a first motor torque measurement, at a time that a motor torque measurement and GTE torque measurement are equal to each other; and
determining the medium value as a multiple of the first motor torque measurement.
8 . The method of claim 4 , further comprising:
selecting, as the non-instantaneous rate, a greater from among the pre-defined rate limit and an augmenting torque limit,
wherein the augmenting torque limit is an inverse of a GTE torque measurement.
9 . The method of claim 1 , wherein generating the second command signal comprises:
setting the motor speed reference value equal to a speed setpoint of the GTE that is based on the difference between the torque load demand and the GTE power measurement, in response to a determination that the condition for operating in the assisted mode is not satisfied; and
varying the motor speed reference value from the speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is satisfied.
10 . The method of claim 1 , wherein the low value is great enough to maintain a minimum limit of electric motor rotor speed and while not reducing a state of change of a battery that provides power to the electric motor.
11 . An electronic device comprising:
at least one processor configured to:
receive a torque load demand associated with a rotor, and a gas-turbine engine (GTE) power measurement among first measurements from a GTE;
determine whether the torque load demand is within operating limits of the GTE without assistance from a motor, based on the first measurements compared to a condition for operating in an assisted mode; and
generate and output a first command signal that sets a motor torque limit, and a second command signal that sets a motor speed reference value based on a difference between the torque load demand and the GTE power measurement,
wherein to generate the first and second command signals, the at least one processor is further configured to:
set or reduce the motor torque limit to a low value and setting the motor speed reference value equal to a speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is not satisfied; and
increase the motor torque limit to a high value and varying the motor speed reference value from the speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is satisfied.
12 . The electronic device of claim 11 , wherein the at least one processor is further configured to:
determine that the condition for operating in the assisted mode is satisfied based on the torque load demand exceeding a steady-state operating limit of the engine or a rate of change of the torque load demand exceeding a transient operating limit of the engine.
13 . The electronic device of claim 11 , wherein the at least one processor is further configured to:
determine that the condition for operating in the assisted mode is not satisfied based on:
the torque load demand not exceeding a steady-state operating limit of the engine; and
a rate of change of the torque load demand exceeding a transient operating limit of the engine.
14 . The electronic device of claim 11 , wherein to generate the first command signal, wherein the at least one processor is further configured to:
reduce the motor torque limit to the low value, including to:
decrement the motor torque limit from the high value to a medium value at an instantaneous rate; and
reduce the motor torque limit from the medium value to the low value at a non-instantaneous rate that is based on pre-defined rate limit.
15 . The electronic device of claim 14 , wherein the at least one processor is further configured to:
determine, as the medium value, a motor torque measurement at a time of satisfying a condition in which a torque difference between the motor torque measurement and a GTE torque measurement is within a threshold.
16 . The electronic device of claim 14 , wherein the at least one processor is further configured to:
determine, as the medium value, a motor torque measurement at a time of satisfying a condition in which an increase of the motor torque measurement stops.
17 . The electronic device of claim 14 , wherein the at least one processor is further configured to:
determine, as a first motor torque measurement, at a time that a motor torque measurement and GTE torque measurement are equal to each other; and
determine the medium value as a multiple of the first motor torque measurement.
18 . The electronic device of claim 14 , wherein the at least one processor is further configured to:
select, as the non-instantaneous rate, a greater from among the pre-defined rate limit and an augmenting torque limit,
wherein the augmenting torque limit is an inverse of a GTE torque measurement.
19 . The electronic device of claim 11 , wherein to generate the second command signal, the at least one processor is further configured to:
set the motor speed reference value equal to a speed setpoint of the GTE that is based on the difference between the torque load demand and the GTE power measurement, in response to a determination that the condition for operating in the assisted mode is not satisfied; and
vary the motor speed reference value from the speed setpoint of the GTE, in response to a determination that the condition for operating in the assisted mode is satisfied.
20 . The electronic device of claim 11 , wherein the low value is great enough to maintain a minimum limit of electric motor rotor speed and while not reducing a state of change of a battery that provides power to the electric motor.