Robust control of pantograph‐catenary system: Comparison of 1‐DOF‐based and 2‐DOF‐based control systems

Abstract

Abstract Compared to control bandwidth, low‐frequency uncertainties or disturbances like step signals can be well rejected by many methods having two‐degree‐of‐freedom (2‐DOF). Due to robustness constraint, technically more challenging is the rejection of medium frequencies, especially for bandwidth‐limited systems. Here, the equivalent‐input‐disturbance (EID) approach is extended to deal with the main medium‐frequency oscillation of a pantograph‐catenary system. First, a general EID estimator is developed with a low‐frequency estimator as a special case. Then, a fair comparison is conducted to clarify the essential differences between the conventional 1‐DOF‐based and the developed 2‐DOF‐based control systems. Furthermore, a robust stability condition is derived for the 2‐DOF‐based closed‐loop control system. A design algorithm together with design guidelines is provided, where the frequency characteristics of the uncertainties are utilized in the parameter design. Finally, simulations are carried out to validate the developed 2‐DOF‐based method for the pantograph‐catenary system in realistic environment.

Keywords

• Optimisation techniques
• Control system analysis and synthesis methods
• Stability in control theory
• Optimal control