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DC microgrid systems based on hybrid photovoltaic-electrical energy storage systems for power generation are widely used in new energy cruise ships. For the problem of power supply voltage unbalance arising when a daily load power supply converter is connected to an unbalanced load or single-phase load, this paper proposes a dead-beat predictive voltage control strategy based on positive and negative sequence separation of output voltage. This strategy can realize control of positive and negative sequence components of the power supply converter voltage under the positive and negative sequence coordinate systems respectively, to ensure the three-phase voltage balance of the power supply converter, enhance the anti-interference ability of the system against unbalanced load and avoid additional power quality control devices. The simulation results show that, after the proposed control strategy is adopted, the voltage unbalance of the daily load power supply converter is reduced from 28% to less than 0.5%, which verifies the effectiveness of the proposed control algorithm .

Multi-source powered mining trucks are expected with broad market prospects, due to the advantages in energy conservation, environmental protection, flexibility and efficiency. The three-level DC/DC converter with excellent input and output characteristics is generally used as an on-board energy interaction device for energy distribution and management between various on-board power equipment and multiple functional loads. In addition to adaption to a variety of power supply modes and battery charging and discharging control, the converter needs to be configured with different control methods and adaptively switchable among different control methods for the diversity of loads; moreover, it is necessary to solve the neutral point voltage balancing under different modes. Taking the on-board DC/DC converter as the research object, this paper first analyzes energy flow, and proposes an energy management strategy for battery charging and discharging, power supply for various loads and feedback depending on current direction, and a unified neutral point voltage balancing strategy for the three-level DC/DC converter under different working conditions, forming a complete set of energy management methodology. The simulation results show that the DC/DC converter applied with this control strategy has a good neutral point voltage balancing effect under different working conditions.