Design of Pi controller with three-loop structure for power balance of turboshaft

Turboshaft control systems are designed to keep the stability of helicopter, which requires that the powerturbine rotor speed remains constant. Furthermore, the power provided by each engine on the same aircraft is probably not equal if the control system provides the same fuel to each one. In this paper, a control loop aiming at balancing engine output torque and load system demand torque was added in the traditional speed-control system. Then a new structure of PI controller was developed with three control loops. Besides, the research showed this control system could be improved to keep the output torque of each engine equal to deal with the different performance degradations of different engines. Finally, the parameters of PI controllers in this control system were achieved by constructing and solving linear matrix inequality constraints based on the theory of regional pole placement for closed-loop system.