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On power stream in motor or drive system

Paszota Z.

Polish Maritime Research

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2016

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nr 4

93--98

EN

In a motor or a drive system the quantity of power increases in the direction opposite to the direction of power flow. Energy losses and energy efficiency of a motor or drive system must be presented as functions of physical quantities independent of losses. Such quantities are speed and load. But the picture of power stream in a motor or drive system is presented in the literature in the form of traditional Sankey diagram of power decrease in the direction of power flow. The paper refers to Matthew H. Sankey’s diagram in his paper „The Thermal Efficiency of Steam Engines” of 1898. Presented is also a diagram of power increase in the direction opposite to the direction of power flow. The diagram, replacing the Sankey’s diagram, opens a new prospect for research into power of energy losses and efficiency of motors and drive systems.

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O strumieniu mocy w silniku lub w układzie napędowym

Paszota Z.

Napędy i Sterowanie

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2016

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R. 18, nr 11

98--103

PL

W silniku lub w układzie napędowym wielkość strumienia mocy rośnie w kierunku przeciwnym do kierunku przepływu mocy. Straty energetyczne i sprawność energetyczna silnika lub układu napędowego powinny być przedstawiane jako funkcje wielkości fizycznych niezależnych od strat. Takimi wielkościami są prędkość i obciążenie silnika. Jednakże obraz strumienia mocy w silniku lub w układzie napędowym jest przedstawiany w literaturze w formie tradycyjnego wykresu Sankeya spadku mocy zgodnego z kierunkiem przepływu mocy. Artykuł nawiązuje do wykresu Matthew H. Sankeya zamieszczonego w jego referacie The Thermal Efficiency of Steam Engines z roku 1898. Przedstawiony jest także wykres wzrostu mocy w kierunku przeciwnym do kierunku przepływu mocy. Wykres ten, zastępujący wykres Sankeya, otwiera nową perspektywę badań mocy strat energetycznych i sprawności energetycznej silników i układów napędowych.

EN

In a motor or in a drive system the quantity of power increases in the direction opposite to the direction of power flow. Energy losses and energy efficiency of a motor or a drive system must be presented as functions of physical quantities independent of losses. Such quantities are speed and load. But the picture of power stream in a motor or in a drive system is presented in the literature in the form of traditional Sankey diagram of power decrease in the direction of power flow. The paper refers to Matthew H. Sankey’s diagram in his paper The Thermal Efficiency of Steam Engines – of 1898. Presented is also a diagram of power increase in the direction opposite to the direction of power flow. The diagram, replacing the Sankey diagram, opens a new perspective of research into power of energy losses and efficiency of motors and drive systems.

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Losses and energy efficiency of drive motors and systems. Replacement of the Sankey diagram of power decrease in the direction of power flow by a diagram of power increase oppo site to the direction of power flow opens a new perspective of research of drive motors and systems

Paszota Z.

Polish Maritime Research

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2013

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nr 1

3--10

EN

Losses and energy efficiency of every drive motor must be presented as functions of physical quantities independent of losses in the motor. Such quantities are speed and load required by the machine or device driven by the motor, changing in the drive operating field. Speed and load of the motor decide of the instantaneous useful power of the motor and also in a differentiated way of kinds and values of losses occurring in the motor. However, losses and energy efficiency of the hydrostatic drive motors and systems are evaluated by researchers and manufacturers as functions of parameters depending on the losses. The basic cause of such situation is the traditional, commonly accepted but erroneous, view of the power flow in the drive motors and systems represented by the Sankey diagram of power decrease in the direction of power flow. It is necessary to replace the Sankey diagram by the proposed diagram of increase of power in the motor and in the drive system in the direction opposite to the direction of power flow. The proposed view of losses and energy efficiency should be applied to all types of motor and drive systems. The aim of this paper is showing the resulting problems of the above postulates, exemplified by operation of a rotational displacement motor in a hydrostatic drive system. In order to make possible objective evaluation of the energy behaviour of different motor and system solutions and sizes, the losses and energy efficiency should be described and compared as dependent on the motor speed coefficient ωM and load coefficient changing in the drive system operating field (0 ≤ ωM< ωMmax, 0 ≤ M< Mmax). The presented proposals open a new perspective of unavoidable research of drive motors and systems, making it possible to compare objectively the energy efficiency of different types of motors and drive systems.