Shark -new motor design concept for energy saving- applied to - VBN

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Chapter 1 Introduction
This fact negates the previous suggestion that small motors should be main focus for energy saving.
The energy consumption depends on various factors such as: rated power range of the motor,
efficiency, annual operating time of the equipment, load 2 factor and usage 3 factor of the motor.
Small motors, although they are sold in large numbers, usually have a lower usage factor than
motors rated in the higher power range. This contributes to their lower energy consumption over a
defined period. Therefore, more energy may be saved by a slight improvement of the efficiency of
large motors than by a significant efficiency improvement of small motors.
In spite of all the international actions intended to promote the use of HEM and in spite of general
demand for energy saving products, the market is still reluctant to make changes. The increased
initial purchase cost necessary for HEM, caused by the use of improved or more material and by the
increased quality of manufacturing, is at the root of this paradox. The selection of a motor by a
purchasing agent is dominated by the purchase price and not by the potential lifetime cost saving
made possible by the use of HEM. It is often forgotten that the purchasing price represents less than
5% of the lifetime cost of the motor [7]. To encourage the HEM market a subsidy of up to 30% of
the HEM price is offered in Denmark [7].
In some reports [12], it is argued that an E-motor (electric motor with incorporated electronics) may
bring more advantage than an HEM. This may be true, but any gain in inherent motor efficiency
may be valuable for energy saving. The interest of this thesis is restricted to improvements related
to the efficiency of the motor itself.
In this introductory section was shown that the general tendency is to reduce the energy used by
electric motors because they represent an important energy consumer in industry. To do so new
standards were approved by CEMEP and high efficiency motors are promoted on the market.
Generally, a better efficiency is achieved by using better or more magnetic material or by
optimisation of the radial cross-section of the electric motor. Both methods are expensive.
Therefore, consideration of the longitudinal cross-section of an electric motor may further improve
the performance of the electric motor or may be considered as an alternative solution to the two
methods mentioned above. This new concept was named Shark concept and is introduced in the
following section.
1.2 Introduction to the Shark concept
Although the development of electrical machines has long been a well-established commercial
enterprise, design investigations and innovations are still in progress. The concept of HEM involves
the use of better quality or of more material and optimisation of the magnetic circuit. A tremendous
amount of research work dedicated to the optimum design of electrical machines has revealed that
the material distribution within the machine is one of the key elements for improving the machine
performances.
A common way to improve the design of an electrical machine is by optimisation of the radial
cross-section [13], [14], [15]. This is governed by considerations relating the cost of manufacture to
the improvement brought by the new geometry of the machine.
2 The load factor is that fraction of the rated load, at which the motor is normally loaded
3 The usage factor is that fraction of time when the motor actually operates