This paper presents an overview of technology related to on-board microgrids for the More Electric Aircraft. All aircraft use an isolated system, where security of supply and power density represent the main requirements. Different distribution systems (AC and DC) and voltage levels coexist, and power converters have the central role in connecting them with high reliability and high power density. Ensuring the safety of supply with a limited redundancy is one of the targets of the system design, since it allows increasing the power density. This main challenge is often tackled with proper load management and advanced control strategies, as highlighted in this paper.

This paper proposes a modified conation of single-phase pack U-cell (PUC) multilevel inverter in which the output voltage has higher amplitude than the maximum dc link value used in the topology as a boost operation. The introduced inverter generates seven-level ac voltage at the output using two dc links and six semiconductor switches. Comparing to cascaded H-bridge and neutral point clamp multilevel inverters, the introduced multilevel inverter produces more voltage levels using less components. The proposed inverter is used in photovoltaic (PV) system where the green power comes from two separate PV panels connected to the dc links through dc-dc converters to draw the maximum power. Due to boost operation of this inverter, two different PV panels can combine and send their powers to the grid. Simulations and experimental tests are conducted to investigate the good dynamic performance of the inverter in grid-connected PV system.

In this paper, a solar PV (Photovoltaic) array, a battery energy storage (BES), a diesel generator (DG) set and grid-based EV charging station (CS) is utilized to provide the incessant charging in islanded, grid connected and DG set connected modes. The charging station is primarily designed to use the solar photovoltaic PV array and a BES to charge the electric vehicle (EV) battery. However, in case of exhausted storage battery and unavailable solar PV array generation, the charging station intelligently takes power from the grid or DG (Diesel Generator) set. However, the power from DG set is drawn in a manner that, it always operates at 80-85% loading to achieve maximum fuel efficiency under all loading conditions. Moreover, in coordination with the storage battery, the charging station regulates the generator voltage and frequency without a mechanical speed governor. It also ensures that the power drawn from the grid or the DG set is at unity power factor (UPF) even at nonlinear loading. Moreover, the PCC (Point of Common Coupling) voltage is synchronized to the grid/ generator voltage to obtain the ceaseless charging. The charging station also performs the vehicle to grid active/reactive power transfer, vehicle to home and vehicle to vehicle power transfer for increasing the operational efficiency of the charging station. The operation of the charging station is experimentally validated using the prototype developed in the laboratory.

In this paper, an implementation of solar photovoltaic (PV) array powered grid connected, residential electric vehicle (EV) charger is presented, which caters the need of an EV, household loads and the grid. The charger is enabled to operate autonomously using PV array for providing an uninterruptible charging and power to household loads. However, in the absence of the PV array or insufficient PV array generation, the grid connected mode of operation is presented. Moreover, the charger is supported with the synchronization and seamless mode switching control, so that the charger automatically connects/disconnects from the grid without disturbing the EV charging and household supply. The charger is also enabled with the vehicle-to-grid (V2G) active/reactive power support to the grid and vehicle-to-home (V2H) power transfer for supporting the local loads in an islanded condition. The charger is also controlled to operate as an active power filter for achieving the unity power factor (UPF) operation and total harmonic distortion (THD) of grid current within 5%. Moreover, for achieving energy management, a dc link voltage regulation based energy management strategy is used and a sliding mode control (SMC) is used for regulating the dc link voltage. For satisfactory operation under distorted voltage condition, a second order generalized integrator frequency locked loop with dc offset rejection (SOGI-FLL-DR), is used to generate the sinusoidal reference grid current. The charger is designed for a single phase 230V, 50Hz grid and it is experimentally validated in the laboratory.

This paper proposes two new open-circuit fault detection methods suitable for the diagnosis of power electronics converters. The faulty semiconductor devices are identified using conducted and radiated electromagnetic signatures of the dc bus through nonintrusive measurements. The first method uses a low-cost electromagnetic interference filter to collect the common-mode emissions signature. The second one utilizes an external antenna to collect the emitted near-field signature. Both methods are tested on a three-level neutral point clamped inverter (NPC) inverter with the aim to identify the clamping diodes open-circuit faults. Indeed, each open-circuit fault affects the common-mode emission signature in the time-domain, while the fast Fourier transform of the emitted near-field showed substantial reduction of spectrum amplitude at a specific radio frequency range and the appearance of a new spectral rail. The effectiveness of these two methods has been tested through numerical simulations and validated by experimental results which confirmed its high performance in detecting single as well as multiple open-circuit faults for three-level NPC inverter.

This paper proposes a cycle life model for lithium-ion batteries. The main objective of this work is to facilitate the electrical simulation of lithium-ion battery aging (due to cycling), and its impact on battery capacity and internal resistance. Most of the reported cycle life models are either: a) physics based, with parameters difficult to retrieve or b) semi-empirical, where the parameter identification process requires large amount of experimental data, huge manpower and test duration lasting from months to years. Moreover, these models tend to be valid only for the underlying battery and not for other battery types. This makes the simulation of lithium-ion batteries cycling effects, difficult to achieve, expensive and time consuming. The model proposed in this paper is based on simple physical equations from fatigue theory and equivalent cycle counting. The parameter identification process is straightforward and requires only few data from battery datasheets and limited (or short duration) cycling experiments. The proposed model is generic and able to represent the impact of common cycle life factors such as: depth-of-discharge (DoD), temperature and C-rate. The model is validated using two lithium-ion battery types (LFP-LiFePO4 and NMC-LiNiMnCoO2) and simulation results are close to reality with an error within 1.5% compared to experimental results.