A novel subspace identification approach with passivity enforcement

This paper presents a subspace-based frequency identification method with passivity enforcement via Linear-Matrix Inequalities to achieve a globally optimal and passive solution. These inequalities are formulated and solved as a convex optimization problem using a state-of-the-art numerical solver. We also apply a weighting methodology to the LMI formulation to enhance the approximation between the model and the measured frequency-domain data. A case study including a coaxial cable experimental setup is presented to showcase and validate the proposed approach. Our results reveal that the proposed algorithm solves passivity enforcement problems in a single step without interactions and is able to successfully estimate passive models within the subspace framework.