An improved high voltage boost Z-source inverter topology is proposed to improve voltage boost ability. Compared to the conventional Z-source inverter, it can produce very high voltage boost with a short shoot-through duty ratio, the voltage stress on Z-source capacitors and inverter-bridge is greatly reduced, and has inherent limitation to inrush current at startup. The addition of a input capacitor and an active switch allows the current in the Z source network to flow in the reverse direction, which adapts to a wide range of the load change. Theoretical analysis, the operation principle of the proposed topology and comparison with the conventional topology are explicitly described. Simulation and experimental results are presented to demonstrate the new features.

In this paper, a variable structure controller for temperature control of the solid oxide fuel cell (SOFC) is proposed. The performance and availability of the SOFC are greatly dependent on its operating temperature. For high efficiency and low degradation of the fuel cell due to thermal cycling, the fuel cell temperature should remain fairly constant during operation. To meet the demands of developing valid control strategies, a control-oriented multi-input multi-output nonlinear thermal model of the SOFC is first developed in this paper. Then, by combining the technique of input-output linearization with variable structure control (VSC) theory, a VSC controller for temperature control is proposed. Simulation results demonstrate the correctness of the proposed control-oriented nonlinear thermal model, while the excellence of the VSC controller for temperature control in the presence of external disturbance is proved.

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The use of green energy to power ships in the marine industry has attracted increasing attention in recent years. This paper presents an inland river cruise ship supplied by a fuel cell (FC) as the main power source and a supercapacitor (SC) as the auxiliary power source. Its propulsion inverter adopts the proposed high-boost Z-source inverter, and the proposed high-voltage-boost Z-source inverter (HVB-ZSI) principle is studied. The advantages of this proposed HVB-ZSI in two cases are verified through simulation. In case 1, it can be seen that the capacitance voltage is only 250 V, and the maximum inductance’s inrush current at the start is less than 200 A. But the capacitance voltage of HVB-ZSI reaches 383 V, and the inrush current is 300 A. While considering different constraints of the propulsion system, four operating modes for the set of the FC and SC are proposed. The small-signal model of the propulsion system is derived, and the control strategy is studied. By controlling the shoot-through duty cycle and modulation factor, the FC power, output power, and state of charge (SOC) of the SC can be controlled. Finally, to verify the performance of the proposed propulsion system, a hybrid power ship prototype equipped with a 7.5 kw propulsion motor is constructed. Four modes of the entire system are simulated by MATLAB/SIMULINK, and its performance is analyzed with experimental results. These results show that the new Z-source propulsion system has a promising application in new energy ships, as it has higher reliability and lower complexity and cost compared to conventional propulsion systems.