This paper presents an iterative method based on conformal mapping and magnetic equivalent circuits for on-load analysis of saturated surface permanent magnet machines with integer slot and fractional slot windings. Magnetic saturation is taken into account by defining additional point wires in the stator slots and interpolar region between the magnets. The added point wires create magnetomotive force equal to the magnetic voltage drops across iron core flux tubes which are calculated using magnetic equivalent circuit. An improved stator tooth model has been introduced which enables more accurate field calculations for tooth geometries with highly saturated tooth tips. The model also takes into account variation of permanent magnet magnetization due to external magnetic field. The proposed method has been implemented on a saturated 12 slot, 10 pole surface permanent magnet machine with nonoverlapping concentrated winding and shows a very good agreement with finite element calculations in terms of flux density, back electromotive force and torque waveforms as well as d and q axis inductances, cross-saturation inductance and permanent magnet flux linkage in both axes.

This study presents an accurate and computationally efficient finite‐element (FE) calculation and modelling methods for the simulation of symmetrical steady‐state load conditions for synchronous generators. For that purpose, two iterative methods are presented, implemented and compared. Those are Newton’s iterative method and the relaxation parameter iterative method, which were both applied to magneto‐static and transient FEs simulations. Various methods for obtaining armature voltage and power angle are proposed and analysed from the computational efficiency and the accuracy point of view. All methods showed good convergence results for solving this particular problem. Calculation results were compared with measurements on two synchronous generators installed in power plants.

This paper presents an experience in the design and implementation of the condition-monitoring system for the synchronous generators whose primary purpose is to record data for the identification of the capability limits of the P–Q diagram of three generators in hydro power-plant. Paper presents details about the monitoring system, the underlying theory of the identification of the synchronous generator model with a focus on the calculation of the capability limits in the P–Q diagram. Furthermore, a computationally efficient method for the representation of capability limits suitable for the implementation within the industrial automation and control system of the power-plant is described in detail. Finally, the capability diagrams for three generators were implemented in the power-plant supervisory control and data acquisition system (SCADA) system.

High-speed electric rotating machines enhance power density and eliminate gearboxes in waste heat recovery microturbines, but conventional designs face high manufacturing costs and complex cooling requirements. This study presents the development, experimental validation, and comparative analysis of high-speed configurations. Initially, a lower-speed induction machine prototype operating at 13,000 rpm was built using standardized components to experimentally validate numerical loss models. Experimental testing of the initial prototype confirmed a total loss of 7.89 kW, closely matching the simulated 7.75 kW. Leveraging these findings, two next-generation topologies of decreased size, an induction machine and a surface permanent magnet machine, were designed and evaluated using finite element method and conjugate heat transfer simulations under sinusoidal and pulse-width modulation excitations. At a 14,000 rpm operational point, the surface permanent magnet prototype outperformed the induction machine configuration, ensuring the lower temperatures of the permanent magnet machine and achieving 63.2 kW of mechanical power and 96.21% efficiency compared to the induction machine's 52.4 kW and 94.64%.This paper builds upon the microturbine generator project introduced at the ICPGEEC 2025 conference, by presenting lighter, higher-speed machine designs.

High-speed electric machines enhance power density and eliminate the need for a gearbox in waste heat recovery microturbine systems. However, existing designs often suffer from high manufacturing costs and complex cooling requirements. This study presents the development, experimental validation, and comparative analysis of three high-speed machine designs. First, a lower-speed induction machine prototype, constructed using standardized components, was tested at an operating speed of 13,000 rpm. This prototype enabled experimental validation of the numerical model used for loss calculations. Experimental results showed total losses of 7.89 kW, closely matching the simulated value of 7.75 kW at an output power of 93.1 kW, i.e., an efficiency of 92.19%. Building on these findings, two smaller machine prototypes were developed: one featuring an induction squirrel-cage rotor and the other employing a surface-mounted permanent magnet rotor topology. Both machines were designed and evaluated using finite element analysis and conjugate heat transfer simulations. Their performance was analyzed under both sinusoidal and pulse-width-modulated voltage supply conditions. At an operating speed of 14,000 rpm, the permanent magnet machine outperformed the induction machine, achieving 63.2 kW of mechanical power and an efficiency of 96.21%, while operating at lower temperatures. In comparison, the induction machine delivered 52.4 kW of mechanical power with an efficiency of 94.64%. The primary novelty and contribution of this work lie in the implementation of a two-pole machine architecture capable of achieving an output power of 100 kW at operating speeds between 20,000 and 25,000 rpm. Compared with similar solutions reported in the literature, the proposed machines feature a simplified bearing arrangement and a more straightforward liquid-cooling system. These characteristics have the potential to reduce manufacturing costs and simplify maintenance during operation.

Directly coupling high-speed generators to turbines or expanders enables compact conversion of low-grade thermal energy from industrial waste heat, geothermal resources, and small-scale renewable sources. For this application, this paper presents a multiphysics comparative assessment of six candidate topologies: three-phase and six-phase surface-mounted permanent magnet, NdFeB and ferrite interior permanent magnet, synchronous reluctance, and induction machines, all evaluated within a common 30 krpm, 750 V DC-link, water-cooled IEC 132 frame envelope. Two-dimensional transient finite element simulations are used to obtain electromagnetic performance maps, torque-speed characteristics, power factor, and efficiency, while thermal and mechanical analyses are used to assess continuous operating capability and rotor integrity. The comparison shows that peak electromagnetic performance alone is insufficient for topology selection, particularly at high speeds. For that reason, the results serve as a design-selection basis for high-speed generator topologies before detailed optimisation and prototype development.