abstract
- This paper investigates how DC-link cable parasitic resistance and inductance affect the stability of a three-phase interconnected converter system composed of an active rectifier and an inverter. The study uses an impedance-based small-signal framework derived from averaged models to characterize the DC-side interaction between both converters. Two proportional-integral control strategies in the synchronous direct-quadrature reference frame are examined to handle the cross-coupling terms introduced by the Park transformation: a precalculated cross-coupling-term scheme and a cross-coupling cancellation scheme. The Nyquist stability criterion and the small-gain theorem are then applied to the resulting impedance models. The results show that a controller that appears stable when the DC-link is assumed ideal may become unstable when cable parasitic resistance and inductance are included. The analysis also shows that increasing the rectifier voltage-loop phase margin and the inverter-side decoupling capacitance improves robustness to DC-link parameter variations. These findings provide model-based design guidance for controller tuning and DC-link design in interconnected converter systems. The present study is limited to averaged small-signal modeling and simulation; switching dynamics, phase-locked-loop dynamics, measurement delay, nonlinearities, and detailed cable-layout effects are not included.