Active stabilization of a poorly damped input filter supplying a constant power load

The presence of an LC input filter in an electrical system often results in degradation of dynamic performance and instability of the system. This paper addresses the global stability study of an electrical system comprised of a DC power supply, an LC filter and an actuator (inverter - permanent magnet synchronous motor or induction motor). Circle criterion is used to study the global stability of the system. In the proposed approach the control structure of the electrical system is slightly modified to implement a nonlinear stabilization structure for improving large signal stability of the system and thus allows reducing the DC link capacitance value. An electrical system consisted of an LC input filter connected to an inverter-PMSM designed for aircraft application is treated as an illustrative example.