Large-Signal Stabilization of a DC-Link Supplying a Constant Power Load Using a Virtual Capacitor: Impact on the Domain of Attraction

It is known that the interaction between poorly damped $LC$ input filters and constant power loads (CPLs) leads to degradation of dynamic performance or system instability. This paper addresses a large-signal stability study and stabilization of an electrical system containing a dc power supply, an $LC$ filter, and a CPL. This latter is realized here by a voltage source inverter supplying a motor drive. To stabilize the system, the control structure is slightly modified to implement a nonlinear stabilization block that virtually increases the dc-link capacitance and, hence, the damping of the system. The main idea consists in adding a capacitive power component to the CPL power reference. This allows reducing the real dc-link capacitance value and volume, which is, for weight and size reasons, an important issue in aerospace applications. The impact on the large-signal stability will be analyzed by estimating the domain of attraction of the operating point. An illustrative example consisted of an $LC$ input filter connected to an inverter-permanent-magnet synchronous motor designed for aircraft applications treated by simulations and experimentation, which confirm the validity of the proposed approach.