Mariusz Korkosz

The design and development of an axial-flux ferrite magnet slotless generator for use in a small-scale wind turbine is described. The 4/4-pole single-phase machine is designed for simplicity and ease of manufacture and it consists of one slotless stator disc. The generator produces approx. 12 W at 1000 rpm with electrical efficiency of up to 46%. Because the efficiency of the machine is important, the power curve characteristics and voltage produced by the generator are investigated. The presented generator should generate sufficient output DC voltage to charge 4 to 5 batteries of 12 volt each. Finally, the finite element (FE) results are compared with measurements on a prototype. The calculated values coincide to a strong degree with the experimental results.

In the paper, alternative technologies of electric machines for domestic appliances were discussed. Nowadays, domestic appliances are used on a mass scale. In most households, there are domestic appliances where electric machines are used. Commutator motors are generally used in domestic appliances due to low costs of production. This is one of their few advantages, whereas to their disadvantages can include low energy efficiency and durability, which is limited by the sliding contact of brush-commutator. In consequence, devices equipped with these motors have low efficiency of energy conversion and are very often unreliable. In recent years, the vacuum cleaner became the receiver of relatively high power from the mains. Therefore, vacuum cleaners were covered by EU regulations. An increase of the energy efficiency of domestic appliances where electric machines are used is possible, among others, by introducing energy- saving technologies in electric machines. They are characterized not only by higher energy efficiency, but also by much longer failure-free operation of domestic appliance drive.

The design of a ferrite magnet generator with trapezoidal shaped permanent magnets and coils for a wind turbine is studied. Based on the 3-D finite element analysis (FEA), the electromagnetic performances of the two generator prototypes and a simple design modification for one of the axial-flux generator prototypes are analyzed. The best generator is chosen from a range of designs, where the goal is to increase the voltage generated by the 8/8 pole and a single-phase slotless machine. Experimental results from a small size prototype machine validate the 3-D FEA models presented, and hence give confidence in their use for design.

In this paper, the series configuration of pole winding connections in each phase of a three-phase 12/8 switched reluctance motor was analyzed. Based on the simulation model, the effect of magnetic couplings on motor properties was determined. Static characteristics were obtained for NNSS and NSNS configurations. Voltage, current, and electromagnetic torque waveforms were determined. Simulation results were verified through laboratory tests.

In the paper, the results of laboratory tests of a surface mounted permanent magnet brushless motor were presented. Two power electronics systems, which are made as inverters for PMSM and BLDC motors, were used. The PMSM inverter supplies the motor with sinusoidal currents and the BLDC inverter supplies the motor with trapezoidal voltage. The motor characteristics and its waveforms were determined when the motor was supplied from the BLDC inverter and the PMSM inverter. A comparison of the influence of the motor supply method on its features and parameters was performed.

A hybrid drive of an unmanned aerial vehicle uses two mechanically coupled drives. In one of the drives, an electrical machine is used. Its role is not only limited to a motoring operation, e.g. during achieving the flight ceiling. The electric machine changes its operation into generating after reaching the flight ceiling, this allows not only meeting current electrical energy demands but also battery recharging. This paper presents the results of laboratory tests of a BLDC machine in motoring and generating operation. Mechanical characteristics of the motor for different supply voltages and external characteristics for generator were determined. The possible energy conversion efficiencies for both motoring and generating operations were determined.