Specific parameters comparison of synchronous reluctance electric drives
The article presents the principles of comparison of different types of synchronous contactless electric drives. The mathematical description of the system is given for comparison. It is shown that classical unregulated synchronous electric drives are inferior to induction electric drives by 30–40%. It is caused by both a decrease in excitation and a decrease in the limiting load angle according to the conditions of static stability. The phase current of electric drives with FRRM has a rectangular shape which allows one to significantly improve the weight and dimensions. In this case, the electric drive with FRRM due to the compensation of the armature transverse response allows improving the system characteristics, so that the induction motor is 10–15% less than the FRRM.
On application of fractional single-toothed concentrated windings in synchronous machines with permanent magnets
Some properties of fractional single-toothed concentrated windings that contribute to their effective application in electrical machines have been considered. Small end windings allow making an electrical machine more compact in the axial direction, which makes it possible to use it in several applications: in motor-wheel drives, in a wind wheel power generator, in an elevator drive without room for a machine, etc. Fractional windings can significantly reduce the cogging torque of an electrical machine. This reduces the cogging torque, which is very important in wind energy, but at the same time it increases the smoothness and accuracy of positioning, which allows it to be used in special electrical machines. One of the drawbacks of the fractional single-toothed concentrated windings is a worse MMF harmonic content. With this in mind, application of a two-layer winding is to be preferred to that of a single-layer one. An example shows application of a fractional tooth concentrated winding in a synchronous engine with permanent magnets to drive the plunger pump used for oil production. The use of a two-layer winding instead of a single-layer one allowed reducing the eddy-current losses in the rotor by 3.7 times and avoiding unacceptable overheating of magnets.
Accurate measurements of output characteristics and detonations of motorbike high-speed racing engine and their optimization at actual atmospheric conditions and combusted mixture composition
Abstract At a motorbike high speed racing engine there is very important an output engine characteristics which depends significantly on a detonation combustion rate, atmospheric conditions and a combusted mixture composition. The combustion process has got a relevant influence on a wear degree of main engine parts or on their damage eventually. The detonation combustion rate is very important because this kind of burning can be not only destructive but a useful phenomenon, as well. If the process of detonation burning is kept on a certain level, it can help significantly to the next increasing of an engine power output. In this article there is described the measurements of output characteristics of a high-speed racing engine which were performed by means of a data-recording system and the detonation combustion was evaluated using a quantitative method. The actual values of atmospheric conditions and the mixture composition were added to the measured values. Then the obtained values are compared visually with a damage degree of an engine piston caused by the detonation burning. The result is a limit value expressed in a number of detonation units related to a run distance interval of the vehicle driven by the high-speed racing engine. In framework of this run distance interval there is the process of detonation burning profitable. As well as it increases an engine power output and together it is not destructive with regard to engine design parts.