Decentralized control of a vehicular microgrid with constant power loads

Constant power loads may form a major proportion of the system loads in automotive power systems. Without proper control the presence of constant power loads in a multi-converter environment can cause system instability. In this paper, the concept of autonomous control of a dc microgrid is extended to automotive power systems. An autonomous control law is derived for an automotive power system which consists of system of parallel connected boost converters supplying a constant power load. The control law derived using the passivity based approach consists of two stages. The first, primary stage involves a non-linear droop of the microgrid voltage with respect to the current supplied by each of the converters thereby enabling current sharing. The primary controller also damps the oscillations in the dc microgrid caused by the presence of the constant power load. The secondary controller adjusts for the voltage deviations due to the primary controller without affecting the current sharing. The conditions to ensure the asymptotic stability of the equilibrium points are derived. Experimental results are presented to verify the proposed control law.