This paper presents the design of an axial-flux permanent magnet (AFPM) generator with two rotors and one coreless stator with planar coils. This geometry has reduced the total mass of the generator and production demands of the machine. The geometry of the coreless AFPM machine enables direct analytical calculation of the magnetic field in the air gap. The analyzed geometry is reduced to the equivalent 2D model. The equivalent circuit parameters are evaluated for the proposed design of the planar coil by the calculation of the magnetic field produced by permanent magnets and stator winding separately. These principles of analytical design of the AFPM machine are integrated into the developed software “deSAX”. The presented analytical approach and the results are validated by 3D finite-element analysis (FEA). The generator is then produced and tested under the off-grid operation and the maximal power 200 W (750 rpm) is obtained according to calculated output characteristics.

The usage of multiphase electrical drives expands the operation possibilities of electrical machines and opens new directions of research on inverter-fed electrical machines. With an increasing number of phases, the standard approach of the electromagnetic design of machines has to be generalized to m-phase systems, which is not usually respected in the literature focused on electric machine design, and it is rarely published. This paper summarizes the specific problems linked with the design of machines with different numbers of phases, focusing on the winding design and the calculation of equivalent circuit parameters. In addition to the direct effect of different numbers of phases, the impact of injecting higher order time harmonic components on the electromagnetic design of electric machines is analyzed. The obtained analytical results are verified by the measurement of a nine-phase experimental induction motor.

Multiphase machines can be operated in interesting operation modes which are not possible when using their three-phase counterparts. Besides fault-tolerant and multimotor operation, torque enhancement by injecting harmonic currents is another of their very important properties. Torque enhancement by injecting harmonic is usually conditioned by the existence of spatial harmonics, typical for concentrated rather than distributed windings. An improved theory of the torque enhancement principle is presented in this paper. The theory is based on the inherent multi-pole behavior of multiphase stator windings supplied by harmonic currents, producing non-zero MMF. As a result, additional torque is produced even with sinusoidal MMF in distributed windings where negligible space harmonics exist. These conclusions are proved by both theoretical analysis and experimental results. Experimental tests were performed on a nine-phase star-connected induction machine with a rated power of 15 kW when supplied by individual fundamental, $3^\mathrm{rd}$ and $5^\mathrm{th}$ harmonic or by their combinations.

In this paper is discussed and evaluated the using of various concept of traction drives in Czech Republic and in the World. The article is focused on application of innovative solutions especially high speed traction drives with permanent magnet synchronous machines. In the research is evaluated the impact of high speed application and assessed the advantages and disadvantages of the new concept and new possibilities with the older types.

The subject of this paper is the calculation of the induction machine air gap flux density distribution. Following previous paper, the parameters affecting the distribution are integrated to create the final no-load flux density distribution. The no-load calculations are valid for every type of winding and can be applied to almost every type of electric machine. To calculate the flux density distribution in loaded condition, the magnitude and phase shift of the rotor current have to be calculated. The rotor magnetomotive force reaction distribution is calculated according to the stator calculations. Based on the equivalent circuit of the machine, the flux density distribution of variable load condition can be calculated. All numerical results are compared with the finite element analysis calculations and the distribution and spectral analysis of the air gap flux density are evaluated in this paper.

This article is focused on review of applications with high speed synchronous reluctance machines. It deals with design, main problems, drives, controlling and challenges in new branch of this electrical machines. The examples and comparison of solution are presented. The problems with construction and some problematic detail are described.