DC-Link Voltage Large Signal Stabilization and Transient Control Using a Virtual Capacitor

It is known that the interaction between poorly damped LC input filters with constant power loads leads to degradation of dynamic performance and instability of the system. This paper addresses the global stability study of an electrical system containing a DC power supply, an LC Filter and a constant power load. This latter is realized by a voltage source inverter supplying a Permanent Magnet Synchronous Motor (PMSM) or an Induction Motor (IM). To stabilize the system, the control structure is slightly modified to implement a nonlinear stabilization block which increases virtually the dc-link capacitance. The main idea consists in modifying the load power by adding a capacitive power component to the load power. This allows reducing the dc-link real capacitance value and size which is important in aerospace applications where engineers are looking for light and small systems. A drive consisted of an LC input filter connected to an inverter-PMSM designed for aircraft applications is treated as an illustrative example. Simulations and experimentations confirm the validity of the proposed approach.