• Energy Research
• 7. Clean energy close

The paper deals with a fuzzy logic based strategy managing the power flows in an hybrid generation plant. Such a plant works in island mode and is composed of: a wind turbine, a photovoltaic generator and a fuel cell/electrolyzer energy storage system. The performances of the proposed strategy are evaluated by simulation in different operating conditions. To this purpose some performance indexes are considered, such as: the frequency deviation, the stability of the DC bus voltage and the AC voltage total harmonic distortion. Simulation results confirm the effectiveness of the proposed power management strategy, providing the ground for the practical realization of a fuzzy logic based control system. Moreover the efficiency of the developed fuzzy logic controller is compared to that of a more conventional controller taking into the fuel cell H 2 consumption, the amount of H 2 generated from the Electrolyzer and the final battery state of charge (SOC).

The paper deals with a fuzzy logic based strategy managing the power flows in an hybrid generation plant. Such a plant works in island mode and is composed of: a wind turbine, a photovoltaic generator and a fuel cell/electrolyzer energy storage system. The performances of the proposed strategy are evaluated by simulation in different operating conditions. To this purpose some performance indexes are considered, such as: the frequency deviation, the stability of the DC bus voltage and the AC voltage total harmonic distortion. Simulation results confirm the effectiveness of the proposed power management strategy, providing the ground for the practical realization of a fuzzy logic based control system. Moreover the efficiency of the developed fuzzy logic controller is compared to that of a more conventional controller taking into the fuel cell H 2 consumption, the amount of H 2 generated from the Electrolyzer and the final battery state of charge (SOC).

A three-phase multi-level multi-input power converter topology is presented for grid-connected applications. It encompasses a three-phase transformer that is operated on the primary side in an open-end winding configuration. Thus, the primary winding is supplied on one side by a three-phase N-level neutral point clamped inverter and, on the other side, by an auxiliary two-level inverter. A key feature of the proposed approach is that the N-level inverter is able to perform independent management of N − 1 input power sources, thus avoiding the need for additional dc/dc power converters in hybrid multi-source systems. Moreover, it can manage an energy storage system connected to the dc-bus of the two-level inverter. The N-level inverter operates at a low switching frequency and can be equipped with very low on-state voltage drop Insulated-Gate Bipolar Transistor (IGBT) devices, while the auxiliary inverter is instead operated at low voltage according to a conventional high-frequency two-level Pulse Width Modulation (PWM) technique and can be equipped with very low on-state resistance Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) devices. Simulations and experimental results confirm the effectiveness of the proposed approach and its good performance in terms of grid current harmonic content and overall efficiency.

A three-phase multi-level multi-input power converter topology is presented for grid-connected applications. It encompasses a three-phase transformer that is operated on the primary side in an open-end winding configuration. Thus, the primary winding is supplied on one side by a three-phase N-level neutral point clamped inverter and, on the other side, by an auxiliary two-level inverter. A key feature of the proposed approach is that the N-level inverter is able to perform independent management of N − 1 input power sources, thus avoiding the need for additional dc/dc power converters in hybrid multi-source systems. Moreover, it can manage an energy storage system connected to the dc-bus of the two-level inverter. The N-level inverter operates at a low switching frequency and can be equipped with very low on-state voltage drop Insulated-Gate Bipolar Transistor (IGBT) devices, while the auxiliary inverter is instead operated at low voltage according to a conventional high-frequency two-level Pulse Width Modulation (PWM) technique and can be equipped with very low on-state resistance Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) devices. Simulations and experimental results confirm the effectiveness of the proposed approach and its good performance in terms of grid current harmonic content and overall efficiency.

Capacity loss over time is a critical issue for lithium-ion batteries powering battery electric vehicles (BEVs) because it affects vehicle range and performance. Driving cycles have a major impact on the ageing of these devices because they are subjected to high stresses in certain uses that cause degradation phenomena directly related to vehicle use. Calendar capacity also impacts the battery pack for most of its lifetime with a capacity degradation. The manuscript describes experimental tests on a lithium-ion battery for electric vehicles with up to 10% capacity loss in the WLTP CLASS 3B driving cycle. The lithium-ion battery considered consists of an LMO-NMC cathode and a graphite anode with a capacity of 63 Ah for automotive applications. An internal impedance variation was observed compared to the typical full charge/discharge profile. Incremental capacitance (IC) and differential voltage (DV) analysis were performed in different states of cell health. A lifetime model is described to compute the total capacity loss for cycling and calendar ageing exploiting real data under some different scenarios of vehicle usage.

Capacity loss over time is a critical issue for lithium-ion batteries powering battery electric vehicles (BEVs) because it affects vehicle range and performance. Driving cycles have a major impact on the ageing of these devices because they are subjected to high stresses in certain uses that cause degradation phenomena directly related to vehicle use. Calendar capacity also impacts the battery pack for most of its lifetime with a capacity degradation. The manuscript describes experimental tests on a lithium-ion battery for electric vehicles with up to 10% capacity loss in the WLTP CLASS 3B driving cycle. The lithium-ion battery considered consists of an LMO-NMC cathode and a graphite anode with a capacity of 63 Ah for automotive applications. An internal impedance variation was observed compared to the typical full charge/discharge profile. Incremental capacitance (IC) and differential voltage (DV) analysis were performed in different states of cell health. A lifetime model is described to compute the total capacity loss for cycling and calendar ageing exploiting real data under some different scenarios of vehicle usage.

An open winding approach can lead to substantial performance improvement on grid-connected induction motors, which are still largely used for constant speed applications. Exploiting an open-end winding configuration to manage bidirectional power flows, the proposed configuration is less expensive than a conventional variable frequency induction motor drive, since a bidirectional controlled rectifier is not required, neither grid-side filters. In constant speed applications the proposed approach not only is able to maximize the average motor efficiency, but also to improve the power factor, limiting the start-up current and compensating the effects of voltage sags. Moreover, an energy storage system can be straightforwardly introduced in the system, enabling load peak shaving and load shifting operations. The proposed approach is first theoretical introduced and analyzed, then a performance assessment is accomplished by simulations.