1,721,135 research outputs found
Feedback Couplings Evaluation on Synthetic Inertia Provision for Grid Frequency Support
Full text linkEmulation mechanisms of the physical synchronous generators obtained through convert-interfaced units are becoming extremely popular in literature. Still the impact of these strategies on networks frequency transients often does not take into account the effect of the converter DC-bus regulation, that plays a significant role in the dynamics definition. Thus two of the main synthetic inertia architectures are analysed both mathematically and experimentally in this article: differently from the available literature, the goal is not just to compare their macroscopic effects on network behaviour, but rather to identify the impact of the multiple internal control feedbacks on the inertia provision itself
Evaluation of the Effects of the Voltage Harmonics on the Extra Iron Losses in the Inverter fed Electromagnetic Devices
No full textEfficiency Improvement of Universal Motors Used in Domestic Appliances
Full text linkA criterion to improve the efficiency of universal
motors used in vacuum cleaners is presented; the lamination
external sizes and the stack length are maintained unvaried.
A mathematical model of the motor is derived, that provides the
expressions of torque, current THD, Joule and core losses as a
function of the magneto-motive forces and the pole flux. The
model is validated by tests and the energy and cost savings
related to winding data changing are evaluated. Then, a new
lamination internal geometry is studied, that de-saturates rotor
teeth, yokes and pole tips, thus increasing the performances
Low-Cost Redesign Criteria for the Efficiency Improvement of Universal Motors used in Domestic Appliances
No full textThe great diffusion of small motors makes interesting their efficiency increase,
but it requires to consider the great commercial competition, the constraints of a
large scale production and the needs of low cost, simplicity, reliability and safety.
A very popular small machine is the universal motor (UM), largely adopted in a
lot of domestic appliances. A typical and important example is the UM used in
high speed vacuum cleaners, produced in several millions per year, with ratings
over one kilowatt, at 30000 – 45000 rpm. Even if the manufacturers made great
technological efforts to improve their performances, an energetic approach to their
design criteria has not been adequately considered yet.
The paper analyses some low cost efficiency improvement opportunities,
considering the “UM - vacuum cleaner” system, under the following constraints:
unvaried lamination geometry and stack length, so that the punching tools and
the frame sizes can be preserved;
torque-speed curve displacement, to be matched with the turbine curve;
modification of field and armature winding data (total copper section
unvaried);
brushes axis displacement, to achieve an acceptable commutation behaviour.
After some motor modelling elements, different redesign strategies will be
analysed and compared. Some redesign examples will be discussed, together with
the corresponding test results, obtained with expressly constructed UM prototypes
A Model for Operation Analysis of High Speed Universal Motors with Triac Regulated Mains Voltage Supply
Full text linkThe universal motor, used in low cost, large scale household appliances, is analysed, developing
its transient model, which takes into account saturation effects: it allows to
analyse the performances and waveforms at the load side (torque, speed) and at the terminals
(voltage, current). The TRIAC regulation of the feeding mains voltage is considered,
evaluating the distortion effects in different operating conditions
Model to Evaluate the Influence of the Winding Data on the Brush Wear in Universal Motors
No full textThe paper analyses the brush wear in two small
rating universal motors, with the same constructive quantities,
except the number of turns of the two coil sections per layer-slot;
in the former motor, the number of turns is the same, in the
latter different, maintaining nevertheless the same sum. Using a
particular equivalent circuit to study the commutation, the
significant quantities influencing the brush wear are found,
explaining the reasons of the different wear in the two cases.
Then, a quantitative evaluation of the brush wear is carried out
Modelling and Experimental Analysis of Core Saturation and Losses of Universal Motors
Full text linkWith the intent to model the global behaviour of
the universal motor, taking into account core saturation and
losses, an equivalent circuit of the machine is described.
A procedure for the calculation of the magnetisation characteristic
is developed, correctly modelling the armature reaction;
a speed-dependent core losses lumped conductance is
evaluated. Simulated and test results validate the model
Evaluation of the Effects of the Voltage Harmonics on the Extra Iron Losses in the Inverter fed Electromagnetic Devices
No full textIn the present paper a method for the calculation
of the extra iron losses occurring in the cores of the inverter fed
electromagnetic devices is described: the loss increase, referred
to the sinusoidal operation, is evaluated, analysing its dependence
on the inverter and on the lamination characteristics
Analytical evaluation of the stator winding temperature field of water-cooled induction motors for pumping drives
No full textEnergy saving improved evaluation of inverter upgrade in submersible pump induction motor drives
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