Port-Hamiltonian formulation and stabilizing controller for a liquid propelled rocket engine

Reusable technology in the field of space launchers requires complex maneuvers to land a launcher first stage, requiring variable thrust from the rocket engine. The developments in electrical actuators allowed the introduction of closed-loop controllers for liquid propelled rocket engines (LPRE). While closed-loop controllers have been suggested in the literature with robustness guarantees, few stability proofs have been given. The LPRE is a complex non-linear system, rendering a direct approach to determine a Lyapunov function complex. In this paper, a reformulation of the state-space equations into a model more adapted to stability analysis is proposed, and a passivity approach is derived to prove the stability. In addition, a closed-loop controller that enforces the passivity of the system is designed, with a new equilibrium assignment. Simulated results illustrate the performances of the closed-loop controlled engine.