High speed operation design considerations for fractional slot axial flux PMSM

This paper discusses intensively the design considerations for the fractional slot axial flux permanent magnet synchronous (AFPMSMs) in order to work efficiently in the constant power speed range, also known as the field weakening (FW) region. The dominant parameter in the constant power speed region is called the characteristic current which equals the ratio of the magnet flux linkage over the synchronous inductance (− ψm/Ls). Several machine parameters is affecting the characteristic current including the machine geometry and the winding configurations. In this paper, the effect of many of these parameters on the FW has been discussed; including the outer diameter, inner to outer diameter ratio, magnet size, slot opening width, slots per poles combinations,and the multi phase configurations for the Axial flux permanent magnet synchronous machine (PMSM). Two main governors are considered to evaluate the parameters’ impact on the machine overall performance; the rated machine efficiency and the torque to weight ratio at the highest values. Selection of these governors is application driven where these governors are the most influencing factors on the axial flux PMSM design. The results of the present analysis show that the fine tuning of the discussed machine parameters would derive the motor to work in the required Constant Power Speed Region (CPSR) keeping the required high efficiency and torque to weight ratio. A previously proved analytical model has been used in this study to overcome the highly time consumption in the finite element model (FEM)

Comparison of three analytical methods for the precise calculation of cogging torque and torque ripple in axial flux PM machines

A comparison between different analytical and finite-element (FE) tools for the computation of cogging torque and torque ripple in axial flux permanent-magnet synchronous machines is made. 2D and 3D FE models are the most accurate for the computation of cogging torque and torque ripple. However, they are too time consuming to be used for optimization studies. Therefore, analytical tools are also used to obtain the cogging torque and torque ripple. In this paper, three types of analytical models are considered. They are all based on dividing the machine into many slices in the radial direction. One model computes the lateral force based on the magnetic field distribution in the air gap area. Another model is based on conformal mapping and uses complex Schwarz Christoffel (SC) transformations. The last model is based on the subdomain technique, which divides the studied geometry into a number of separate domains. The different types of models are compared for different slot openings and permanent-magnet widths. One of the main conclusions is that the subdomain model is best suited to compute the cogging torque and torque ripple with a much higher accuracy than the SC model

Coupled electromagnetic and thermal analysis of an axial flux PM machine

The rotor discs in axial flux permanent magnet (PM) machines have similar properties as a radial fan, and therefore, the convective cooling may have a significant influence on the thermal design of these machines. To research the impact of convective cooling on the thermal properties of axial flux PM machines, a coupled electromagnetic and thermal model is introduced in this paper. This technique models a segment of the stator and the rotor only and links them together by analytical equations of the convective heat transfer at different boundaries of the machine model. This results in an accurate and time efficient multiphysics model. The coupled electromagnetic and thermal modeling technique is validated with measurements on a 4 kW axial flux PM machine having the yokeless and segmented armature topology

Wide bandgap based modular driving techniques for switched reluctance motor drives

In switched reluctance motors, the stator can be seen as comprising a stator yoke and a modular tooth-coil construction. Each module consists of a concentrated winding wound around a steel pole. In the conventional driving technique, depending on the number of the stator poles, a number of coils are connected together and driven from one asymmetric H-bridge. Another possible driving technique is the modular one in which each stator coil is driven by a separate asymmetric H-bridge. In this way, the fault tolerance of the drive is highly enhanced. In this paper, three modular driving techniques are proposed, simulated and compared to the conventional one. The difference between the three modular techniques is in the number of turns per stator coil and the DC-link voltage compared to the conventional one. The first technique maintains both the number of turns per coil and the DC-link voltage, the second one maintains the number of turns per coil while halving the DC- link voltage and the last one maintains the DC-link voltage and doubles the number of turns per coil. All the techniques are applied on a 6/4 SRM machine. The technique that maintains the DC-link voltage and doubles the number of turns shows superior performance in terms of the drive efficiency and the converter power density but results in the highest torque ripple. The technique that halves the DC-link voltage achieves a low torque ripple and an efficiency equal to the conventional technique. The converter is designed using SiC technology to enable higher switching frequency capability so that, a smaller DC-link capacitance can be obtained and a high drive efficiency as well

Multi-objective multi-verse optimization of renewable energy sources-based micro-grid system: Real case

Hybrid micro-grid systems (HMGS) are small scale power system where the energy sources are installed to supply local customers. These systems may be considered as promising energy solution to meet the increased in energy demand and traditional sources depletion. Cost of electricity, system reliability, and environmental impacts of the system are three design criteria that must be considered in obtaining the accurate parameters of hybrid renewable energy system components. In this paper, hybrid micro-grid renewable energy system includes photovoltaic system, (PV) wind energy system, (WES) battery bank, (BB) and conventional diesel generator (DG) are proposed to meet the energy requirements in remote area, located in Red Sea called city of Bernice, Egypt, at 23° 54′ 31″ N, 35° 28′ 21″ E. Optimization of Cost of Electricity (COE), Renewable Factor (RF), and Loss of Power Supply Probability (LPSP) are main objective of the designing process of the hybrid system considered as the objective functions. Then, Multi-objective multi-verse optimization (MOMVO) algorithm is used with considering two scenarios, the first one is renewable sources and the second is renewable/diesel energy source. All the possible HMGS configurations namely: PV/battery, wind/battery, PV/wind/battery and PV/battery/diesel, wind/battery/diesel, PV/wind/battery/diesel are studied and analyzed. Moreover, one year hourly meteorological weather data for case study are recorded. Reverse osmosis desalination (ROD) is considered in conjunction with the residential load. The proposed power management strategy is used to manage the system operation when supplying the load. A linear fuzzy membership function is used for purpose of decision making. The simulation results show that MOMVO produces appropriate components size and the PV/wind/battery/diesel is the optimum configuration with values of COE = 0.2720$/KWh, LPSP = 0.1397, and RF = 92.37% at w_1 = 0.5, w_2 = 0.3, and w_3 = 0.2. Sensitivity analysis is performed to show the effect of changing system parameters on the objective functions. It is also shown that the techno-economic feasibility of using HMGS for rural electrification systems and enhance energy access.http://purl.org/coar/resource_type/c_650

Impact of loading capability on optimal location of renewable energy systems distribution networks

A distribution system’s network reconfiguration is the process of altering the open/closed status of sectionalizing and tie switches to change the topological structure of distribution feeders. For the last two decades, numerous heuristic search evolutionary algorithms have been used to tackle the problem of network reconfiguration for time-varying loads, which is a very difficult and highly non-linear efficiency challenge. This research aims to offer an ideal solution for addressing network reconfiguration difficulties in terms of a system for power distribution, to decrease energy losses, and increase the voltage profile. A hybrid Genetic Archimedes optimization technique (GAAOA) has also been developed to size and allocate three types of DGs, wind turbine, fuel cell and PV considering load variation. This approach is quite useful and may be used in many situations. This technique is evaluated for loss reduction and voltage profile on a typical 33-bus radial distribution system and a 69-bus radial distribution system. The system has been simulated using MATLAB software. The findings suggest that this approach is effective and acceptable for real-time usage.http://purl.org/coar/resource_type/c_650