Sultan Jumayev, Aleksandar Borisavljevic, Konstantin Boynov, Juha Pyrhönen and Elena A. Lomonova
The purpose of this paper is to give a simple, fast and universal inductance calculation approach of slotless-winding machines and comparison of inductances of toroidal…
Abstract
Purpose
The purpose of this paper is to give a simple, fast and universal inductance calculation approach of slotless-winding machines and comparison of inductances of toroidal, concentrated and helical-winding machines, since these winding types are widely used among low-power PM machines.
Design/methodology/approach
Harmonic modeling approach is applied to model the magnetic field of the windings in order to calculate the synchronous inductances. The method is based on distinction between electromagnetic properties of different regions in the machine where each region is represented by its own governing equation describing the magnetic field. The governing equations are obtained from Maxwell’s equations by introducing vector potential in order to simplify the calculations.
Findings
Results of the inductances of toroidal, concentrated and helical-winding slotless PM machines, which have the same torque and dimensions, obtained by the proposed analytical method are in good agreement with 3D FEM, where the relative difference is smaller than 15 percent. However, the calculation time of the analytical method is significantly less than in 3D FEM: seconds vs hours. Additionally, from the results it is concluded that the toroidal-winding machine has the highest inductance and DC resistance values among considered machines. Helical-winding machine has lowest inductance and DC resistance values. Inductance of concentrated-winding machine is between inductance of helical and toroidal windings; however, DC resistance of the concentrated windings is comparable with resistance toroidal windings.
Originality/value
In this paper the inductance calculation based on harmonic modeling approach is extended for toroidal and helical-winding machines which makes the method applicable for most of the slotless machine types.
Details
Keywords
Matti Lehtovaara, Matti Karvonen, Rahul Kapoor, Tuomo Sakari Kässi and Juha Pyrhönen
The purpose of this study is to evaluate the linkages between the technological, market and political environment in the wind power industry and their contribution to market…
Abstract
Purpose
The purpose of this study is to evaluate the linkages between the technological, market and political environment in the wind power industry and their contribution to market diffusion.
Design/methodology/approach
The evaluation is based on a literature review of the wind power industry and policy issues in selected countries, patent and financial analyses of leading European firms and semi-structured interviews of energy experts.
Findings
The results reveal that the industry is policy-driven and appropriate energy politics are crucial in continuing the rapid wind power market diffusion during the next decades. Wind power technologies are in an accelerating stage of evolution, and competitive technologies contribute to market diffusion and firms’ financial performance. However, without adequate energy subsidies and emission trading schemes, the industry will not be competitive in the energy markets, where other energy sources, including fossil fuels, are also subsidized.
Research limitations/implications
This case focuses mainly on the leading European industry actors and has a European perspective in policy issues. The analyses are limited to the main support mechanisms and countries where the diffusion of renewable energy has been rapid.
Practical implications
The wind power industry is still in the emerging phase in its life cycle, and well-planned and efficiently implemented public support schemes are needed in order for the firms to compete successfully in the markets. The industry will probably be competitive without subsidies in 10-20 years.
Originality/value
The evaluation of the given indicators and political environment will give insight into the competitive environment and factors behind the diffusion of emerging technologies.
Details
Keywords
Aron Szucs, Zlatko Kolondzovski, Jan Westerlund and Juha Vahala
The thermal management of electrical insulations poses a challenge in electrical devices as electrical insulators are also thermal insulators. Diamond is the best solid electrical…
Abstract
Purpose
The thermal management of electrical insulations poses a challenge in electrical devices as electrical insulators are also thermal insulators. Diamond is the best solid electrical insulator and thermal conductor. This can lead to a paradigm change for electrical machine winding and lamination insulation design and thermal management. The paper introduces these techniques and discusses its effect for the design of electrical machines and its potential consequences for electromagnetic analysis, for example, in multi-physics modelling. The diamond winding insulation is patent-pending, but the diamond enriched lamination insulation is published for the benefit of the scientific community.
Design/methodology/approach
The windings of electrical machines are insulated to avoid contact between the coil and other conductive components, for example, the stator core. The principle of using mica tape and resin impregnation has not changed for a century and is well established to produce main insulation on a complex conductor shape and size. These insulations have poor heat-conducting properties. Similarly, the insulation of laminated steel sheets comprising the stator and rotor restrict heat flow. Diamond-based insulation provides a new path. Increased thermal conductivity means reduced temperature rise and the reduced thermal time constants in multi-physics simulations and system analysis.
Findings
The largest benefit of a diamond-based core insulation is in electrical machines in which the losses are conducted axially to the coolant. These are machines with radial ducts and effective cooling in the end regions. The main benefit will be in reducing the number of radial ducts that positively affect the size, production costs and the copper losses of the machine. The increased thermal conductivity of the diamond insulation system will reduce the thermal constants noticeably. These will affect system behavior and the corresponding simulation methods.
Originality/value
Diamond insulation can lead to a paradigm change for electrical machine winding and lamination insulation design and thermal management. It might also lead to new modeling requirements in system analysis.