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.