Enhanced DC-AC Converter Control using Soft Saturation Inductor Filters

Inductor filters with soft saturation are increasing due to their ability to provide stable performance in power electronics. Compared to hard saturation, soft saturation offers a smoother reduction in inductance, which enhances circuit stability and reduces the risk of current spikes. For DC-AC power converters using LCL, inductor filters with soft saturation affect the power-sharing between energy sources of the microgrid. The leading cause is the DC-AC power converter output impedance model and the nonlinear characteristics of the inductor, which affects the sharing of reactive power. In this study, we proposed an algorithm to control the DC-AC converter output impedance, assuming the prior knowledge characteristics of the nonlinear inductance with soft saturation are known. The proposed algorithm collects nonlinear information about the coil at each sampling time, thereby calculating the required amount of inductive reactance. At the same time, to ensure the system achieves the lowest reactive power-sharing error, a set of integral calculation functions is also integrated into the proposed controller. It can be seen from the simulation results that the proposed algorithm achieves the desired power sharing with the ability to reduce the nonlinear characteristic of the inductor.