Additive manufacturing is acknowledged as a key enabling technology, although its adoption is still constrained to niche applications. A promising area for this technology is the production of electrical machines (EMs) and/or their main components (e.g. magnetic cores, windings, heat exchangers, etc.) due to the potential of creating lightweight, highly efficient rotating motors, suitable for applications requiring a low moment of inertia. This work investigates the readiness of metal additive manufacturing, specifically Laser Powder Bed Fusion (LPBF), applied to the field of EMs to bridge the gaps of how to use this technological approach in this field. A soft magnetic material featuring high silicon content (Fe-5.0%w.t.Si) has been developed for LPBF and a rotor has been 3D-printed for a switched reluctance machine. The printed rotor was assembled into a conventionally laminated stator and the performance of the whole machine was evaluated. Its performance was compared against an identical machine equipped with a laminated rotor of the same dimensions made of conventional non-oriented silicon steel. A comparative study was carried out through both finite element simulations and experimental tests. The efficiency of the two machines was assessed together with the principal electrical and mechanical quantities under several operating conditions.

Vehicle-to-Grid chargers (V2Gs) are currently considered a key component for supporting future power systems in primary and especially secondary frequency regulation. Most of the research works conducted so far on this topic are based on a vehicle-centric perspective, whereas global approaches where the impact caused by fleets of V2Gs is studied from the perspective of an entire electric grid remain quite unexplored. In particular, the effects of aggregating different amounts of V2Gs from the HV, MV and LV subgrids to participate in frequency control represents a novel aspect to be investigated, which is expected to possess a strong potential for further improving the aggregation processes. To this end, this work presents a “global working framework” developed to evaluate the impact on an entire electric system of V2Gs participation in frequency regulation. A reality-based electric network is considered, where two HV, three MV and ten LV subgrids are interconnected. The effects of four different percentages of V2Gs aggregated from the HV, MV and LV subgrids are evaluated for two V2G installed capacities, 10 MW and 20 MW. Results are finally analyzed, including frequency vs time response, rate of change of frequency, grid losses, etc., and valuable knowledge, insights and guidelines are obtained for guiding future grid-level aggregation optimizations of V2Gs participation in frequency regulation.

In the design processes of Switched Reluctance (SR) Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine are the duration of the energizing period and the advance of the turn-on instant, i.e., advance angle. The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element-based iterative methods. In this article, a simple, yet novel analytical model is proposed to cater for the torque-maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this article is shown by the improvement in computation time, without any significant loss of accuracy.

A critical aspect of distributed generation systems focuses on the installation of Electrical Energy Storage Systems in customer-side facilities. In this scenario, flywheel technology is challenged to provide high levels of safety, compactness and competitive cost. This work presents a novel, one-body flywheel scheme based on a switched reluctance machine, whose laminated rotor fulfils both the motor/generator and energy storage functions. The one-body architecture enhances compactness and robustness, whereas the laminated rotor ensures high safety. The design of this flywheel scheme is characterised by a widely different set of trade-offs compared to conventional schemes. In order to prove the feasibility of the proposed scheme and to highlight its design trade-offs, a 60kW, 2.2kWh one-body flywheel is presented as a case study, along with some preliminary experimental results.

In a bid to respond to the challenges being faced in the installation of flywheel-based electric energy storage systems (EESSs) in customer-side facilities, namely high safety, high energy/power densities and low cost, research work towards the development of a novel, one-body, laminated-rotor flywheel, based on a switched reluctance machine (OBOLAR-Fly SR machine) is presented, where the laminated rotor provides both the energy storage and motor/generator functions. The one-body architecture improves compactness and robustness. Besides, the rotor’s laminated body ensures inherently high safety. From the design perspective, the rotor’s dual purpose causes the traditional electrical machines design aspects, such as power development, cooling, losses, torque ripple, etc., to clash with the typical requirements of a flywheel, namely in-vacuum operation and moment of inertia. This results in six main trade-offs to be addressed during the design process: rotor material, speed ratio, number of drive phases, split ratio, optimal vacuum level, and controller hysteresis band. A 60 kW, 2.2 kWh OBOLAR-Fly SR system is developed with a twofold objective: (1) provide an in-depth description of the six bespoke design trade-offs and give some useful guidelines to tackle them; (2) prove the OBOLAR-Fly concept and compare the prototype’s performance with the current state of the art flywheels. Preliminary experimental results prove the viability of the OBOLAR idea and show its competitiveness in terms of efficiency and power density. On the other hand, a gap in energy density to be filled in future research works is highlighted.

The need to reduce computational burden in the preliminary design stage of switched reluctance machines is fostering the interest in design-oriented analytical modelling. To this end, this work proposes a novel design-oriented analytical model that comprises two main parts, each of them containing an original scientific contribution: 1) a new interpolation technique for the flux loci based on 2 ${\text{nd}}$ -order Fröhlich-Kennelly equations, and 2) an analytical model that calculates flux linkage in partial overlap and saturated conditions. The model is validated against finite element analyses of four switched reluctance machines and the experimental results of a physical prototype. Finally, an in-depth discussion on the use, accuracy and limitations of proposed analytical model is provided.