Proposal to raise minimum efficiency level
While Europe keeps on discussing how motor efficiency should be monitored, the U.S. is about to take yet another step further in their motor efficiency programme.
Under the driving force of the American Council for an Energy-Efficient Economy (ACEEE) and the National Electrical Manufacturers Association (NEMA), the U.S. has succeeded in significantly transforming their motor marketplace over the past 20 years. In 1992, the Energy Policy Act (EPACT-92) set a minimum efficiency performance standard (MEPS) for certain types of motors. This was followed by the NEMA Premium voluntary labelling programme to encourage companies that want go further than the obligatory standard.
Last month, ACEEE, NEMA, and two utility companies proposed a plan to Congressional leaders to increase the existing MEPS-values and to expand the MEPS coverage to many other types of motors.Read full article
The paper presents possibilities of so-called circuital mathematical models of electric machines, in which the machine is treated as a set of magnetically coupled coils. It is a very popular class of models used for analysis of operational conditions of electric machines. However, the progress in numerical solutions of electromagnetic filed causes the interest of researchers to shift into so-called field-models.Read full article
If you live in or visit some of the megacities with transportation problems you surely find yourself envying the motorcyclists. Cruising between the cars, even without travelling at high speeds, they are reaching their destination well ahead of those of us in cars. Here is the ultimate solution: a solar powered motorcycle energy storage capacity for 20km and a top-speed of 50 km/h!Read full article
The subject of the paper is the comparison of four complementary methods of the rotor loss estimation in a PM SM, supplied by a PWM voltage source. An ANSYS based finite element model produces values of W, the magnetic energy stored, and P, the rotor losses. On analytical level the machine is represented by a parallel two elements equivalent circuit for each voltage harmonic. Its parameters are estimated using P and W values.Read full article
Projections according to Shell
In their "Sustainability Report 2006" Shell gives a few key figures to paint a picture of the world in 2050 and to compare it with the world we are living in today, and the world as it was in 1907, when Shell was founded.
In 2050 the world will
Optimizing the efficiency of modern asynchronous machines requires the knowledge of the particular loss components. In this contribution a method shall be presented, where by the transient FEM-calculation the copper losses in the rotor bars by harmonic field effects and the consequential originating harmonic currents can be estimated. By this way the determination of the current density of the rotor current harmonics is carried out along the height of the rotor bar.Read full article
Disturbing vibrations and noise of electrical machines are gaining impact. Therefore, it is necessary to estimate the electromagnetic, structure-dynamical, and acoustic behavior of the machine during designing and before prototyping. An adequate tool is numerical simulation applying the Finite-Element Method (FEM) and the Boundary-Element Method (BEM) allowing for the structured analysis and evaluation of audible noise also caused by manufacturing tolerances.Read full article