Model based moving horizon optimal modes-switch schedule in hybrid powertrains for marine applications

Abstract

Nowadays, the hybridisation and the electrification of the powertrains for the marine sectors are of paramount importance to reduce their carbon footprints. In this paper, a novel method is proposed to schedule the modes-switch of an hybrid powertrain for marine applications. The considered system is composed of an Internal Combustion Engine mounted in parallel with a Lynch DC Brushed Electric Machine to deliver power at the propeller shaft. The two key-findings of this paper are: i) A compact mathematical representation of the powertrain to model the energy balances and switching of the different modes of operation. ii) A novel graph-inspired approach to determine the optimal operational mode sequence. The objective is to find the modes schedule over a fixed time horizon that minimises both the fuel consumed and the number of modes changes. The solution is motivated by both the moving horizon principle and the shortest path identification algorithm, and it also relies on a predictive information of the power cycle. Numerical simulations are undertaken, showing the benefits of the proposed scheme. The proposed method is convenient to scale up for the integration of additional energy storage components or new modes of operation.