Model Predictive Control for Hybrid Electric Propulsion Power Split
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Solution Overview
Problem
Determining an optimal power split between a gas turbine engine and electric motors in hybrid electric propulsion systems is challenging, particularly in managing operating limits and energy efficiency for aircraft propulsion.
Innovation Solution
A model predictive control (MPC) system determines a power splitting profile between a gas turbine engine and electric motors based on available electrical power, operating limits, and target fan speed, iteratively adjusting to manage approaching limits and optimize energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If model predictive control is used to determine optimal power split, then fuel efficiency is improved, but system complexity increases
Solution Approach 1:
The MPC controller performs predictive calculations in advance to determine optimal power split strategies before executing them. By predicting future system states and pre-calculating control actions, the system achieves optimal fuel efficiency without requiring complex real-time adjustments during operation.
Solution Approach 2:
The MPC implementation incorporates continuous feedback from the HEP system to adjust power split decisions. The controller monitors actual system performance and compares it with predicted outcomes, dynamically adjusting control parameters to maintain optimal fuel efficiency while managing system complexity through adaptive rather than static control.
2Productivity
If multiple electric motors are used to rotate different shafts, then propulsion efficiency is improved, but control difficulty increases
Solution Approach 1:
The control system segments the propulsion control into distinct modules, with each electric motor controlled independently based on its specific shaft's requirements. The MPC divides the overall power split problem into separate control tasks for each motor-shaft combination, making the control of multiple motors more manageable while maintaining propulsion efficiency.
Solution Approach 2:
The control system dynamically adjusts the operation of each electric motor based on real-time conditions. The MPC continuously optimizes the power distribution to each motor according to changing flight conditions, load requirements, and motor performance characteristics, enabling efficient multi-motor operation without excessive control complexity.
3Reliability
If operating limits are strictly enforced, then system reliability is improved, but operational flexibility decreases
Solution Approach 1:
The MPC controller incorporates operating limits into its predictive model in advance. By pre-defining safe operating boundaries for temperature, pressure, and other critical parameters, the system ensures reliability is maintained while still allowing flexible operation within those boundaries. The controller predicts future states and prevents limit violations before they occur.
Solution Approach 2:
The system dynamically adjusts operating parameters within acceptable ranges to maintain flexibility while respecting limits. The MPC modifies control parameters such as power split ratios, motor speeds, and torque distribution to optimize performance without violating operational limits, thereby maintaining both reliability and adaptability.
Data Source
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AI summary
A method for a hybrid electric propulsion (HEP) system includes determining a target fan speed for a HEP system (10). The HEP system (10) includes a gas turbine engine (11) and at least one electric motor (12A, 12B) configured to rotate a respective shaft (15, 16) of the gas turbine engine (11). The method also includes determining an amount of electrical power that is currently available to the HEP system (10); utilizing a model predictive control (30) to determine, based on the amount of available electrical power and a plurality of operating limits of the HEP system (10), an effector command set (42) that includes a power splitting profile (44) indicating a power split between the gas turbine engine (11) and the at least one electric motor (12A, 12B) for achieving the target fan speed; and implementing the effector command set (42). A controller for a hybrid electric propulsion (HEP) system is also disclosed.