2013 Third International Conference on Intelligent System Design and Engineering Applications
Analysis of the Performance of the asynchronous motor in the high temperature
Shan Baia,Shenglei Shib and Peng Duc
Shenyang University of Technology, Liaoning China
bais_dq11 @126.com,
Abstract. To address the issue that each performance index of
the asynchronous motors has a great change with temperature
change, based on the basic knowledge of the principles an
design of asynchronous motors, combined with high
temperature characteristics of parts material of asynchronous
motor, using MATLAB software, depending on the changes of
the stator and rotor resistances with temperature change, this
paper established the mathematical model, analyzed the
performances of high asynchronous motor in the high
temperature and the impact of the change of resistance.
Further more, this paper analyzed the effect of the high
temperature characteristics of magnetic materials on the
performance of asynchronous motor and provided a reference
for the design of the high temperature asynchronous motor.
Keywords: asynchronous motor
characteristics of asynchronous motor
I.
temperature and the impact of the change of resistance.
Further more, this paper analyzed the effect of the high
temperature characteristics of magnetic materials on the
performance of asynchronous motor and provided a
reference for the design of the high temperature
asynchronous motor.
II. PROPERTIES OF MATERIALS
The main materials of the motor are copper and
aluminum conductors, insulation materials and silicon
steel magnetic material. The performances of these
materials have a obvious change in the high temperature.
These changes directly affect the performance parameters
of the motor. As temperatures rise, the resistivity of copper
alloys has a obvious change. Resistivity of different copper
alloys with temperature has different changes with
temperature rise. Under normal circumstances, the curve
of the resistance changes with temperature is a straight
line[4].Working
environment
temperature
of
high-temperature motor belongs to the low temperature
section relative to the material itself. Therefore, the change
of the stator and rotor resistance can be considered linear.
This feature can use a resistance temperature coefficient
to represent. It is equal to the temperature changes with the
resistance of changes.
A large number of experimental measurements show
that copper resistance temperature coefficient is 0.00393
per Celsius degree. Magnetic material usually cannot be
used at high temperatures. One of the most important
factors is that magnetic properties of magnetic material as
the ambient temperature rises significantly changed. Even
when it reaches a certain temperature, magnetic material
loses its magnetism and cant be used as electrical material.
Temperature in which the magnetic material loses its
magnetism is called Curie point. Different materials have
different Curie points. Curie point is determined by the
Atomic nature of matter[5]. As the ambient temperature
rises, the magnetic characteristics of magnetic materials
change. Derived from the molecular field theory or
quantum theory, magnetization is according to certain
rules in decline until the Curie point. In General, when
temperatures rise, permeability increases and coactivity
and iron loss falls[6]. Main magnetic material of the motor
is silicon steel. Usually silicon steel is done at room
temperature soft magnetic materials. Considering it as a
high-temperature magnetic material to be used, some
issues must be taken into consideration, such as [7]:
high temperature
INTRODUCTION
With the development of science and the progress of
the society, aviation, nuclear energy and military industry
obtained great progress. These developments in the field
make the work environment of the asynchronous motor
deteriorated, such as: serious radiation, and high
temperature. This hot work environment either on the
dielectric strength of the motor or on the electrical
conductive magnetic properties of materials has a huge
impact, and this effect is also directly affect motor
performance. At present, the research on asynchronous
motor in high temperature, mainly concentrated in the
high temperature resistance of the motor and reduce motor
temperature rise[1]. However, the studies on the high
temperature properties of induction motor are very less.
Now, in the design and manufacturing process of
high-temperature induction motor, two main factors are
dielectric strength and temperature rise[2]. Practical using
method of asynchronous motor at high temperature is
reducing the power for using[3]. These methods cant
make full use of the motor. Therefore, this paper in both
theoretical and practical aspects is of great significance.
Based on the basic knowledge of the principles an
design of asynchronous motors, combined with high
temperature characteristics of parts material of
asynchronous motor, using MATLAB software,
depending on the changes of the stator and rotor
resistances with temperature change, this paper
established the mathematical model, analyzed the
performances of high asynchronous motor in the high
978-0-7695-4923-1/12 $26.00 2012 IEEE
DOI 10.1109/ISDEA.2012.82
333
1. Curie point decreased with the increase of the silicon
content. Therefore, the content of silicon in the alloy
should not be higher than 3.5%.
2. When the content of silicon in the alloy at 3%, Curie
temperature is about 720 Celsius degree. Saturation
magnetization intensity decreases with the temperature
rise. So the temperature can not be higher than 620 Celsius
degree.
3. Due to high temperature mechanical performance is
not good, silicon steel is not suitable for high temperature
rotor material.
writing a program, computing and analyzing, some results
can be obtained.
Figure 1 show that efficiency has a larger decline with
the increase of temperature, form 89% to 73%, by 16%;
Figure 2 show that rated speed declines from 1460 rpm to
1332 rpm; Figure 3 show that maximum torque ratio
decreased from 2.275 to 1.65. The performance
parameters have a greater decline.
Because the stator and rotor winding metal material
resistivity increases linearly with ambient temperature
increasing, stator and rotor resistance increases linearly;
the load torque of the motor is a constant, Stator and rotor
current changes little, stator and rotor copper loss
increases, total loss increases and efficiency declines.
Because the motor efficiency decline, rated output power
will have a corresponding decline. As the load torque is
unchanged, motor rated speed will have a corresponding
decline. At the same time, it leads the maximum torque
multiple also has the corresponding decline that stator and
rotor resistance increases with temperature, so that the
motor overload capacity is insufficient, and stability
becomes bad.
III. PRINCIPLES AND ASSUMPTION
In the asynchronous motor theory and practical
analysis, equivalent circuit method is the most commonly
used analysis method. The calculation and analysis of high
temperature performance in this paper is mainly based on
the T type equivalent circuit diagram[8].
High temperature properties of magnetic materials
should not be carried out by simulation analysis. Therefore,
in the establishment of mathematical model of
asynchronous motor for high performance calculation, the
effect of magnetic material on the performance of motor
will not be considered. On the basis of the resistance
calculation and analysis of the influence, and then
according to the magnetic properties of material at high
temperature, the effect of the high temperature properties
of magnetic material on the performance of motor will be
considered as a qualitative analysis[9].
The simulation calculation is computing asynchronous
motor performance under the conditions of change of
resistance with temperature. Considering that there are
many influential factors on motor performance in high
temperature, special assumptions are made as follows:
1. The motor can be used in a high temperature
environment and operate normally and steadily.
Mechanical and stray loss are as the same as those in the
normal temperature.
2. Motor under the high temperature environment is an
isothermal body; temperature in each part is the same as
the environmental temperature.
3. Motor magnetic material is not affected by
temperature, various performance parameters do not
change with the temperature.
4. Structural shape does not change with temperature,
the thermal expansion of materials with negligible effects.
As the above assumptions and formula, the
mathematical model for change of resistance with
temperature will be established to calculate and analyze
the performances of motor. This calculation is based on the
example in asynchronous motor design.
Fig 1 the efficiency curve
Fig 2 the rated speed curve
IV. RESULTS AND ANALYSIS
As the above principles and assumptions, by using
MATLAB software, establishing mathematical model,
334
3. As the temperature increases, the maximum torque
multiple decreased obviously, reduced the overload
capacity.
4. Due to the high temperature properties of magnetic
materials, electrical reactance increased, the power factor
degraded.
5. Material iron loss declined with the increase of
temperature, it caused that the downward trend of the
efficiency was improved to a certain extent.
According to the above conclusion, in progress of
designing asynchronous motor used in high temperature,
following suggestions should be considered:
1. Using the material with low resistivity and low
temperature coefficient of resistance as the conductor.
2. Properly increasing machinery matching, reducing
mechanical loss.
3. Improving the voltage level, as far as possible to
reduce rotor current, reducing the copper loss.
In the future re research, the effect of the high
temperature characteristics of the materials on the
performance of motor will be further studied. By coupled
field and circuit analysis, next research will further study
the changes of performance of motor in high temperature
and make simulation analysis.
Fig 3 the biggest torque curve
Magnetic material properties change with temperature.
As mentioned before, magnetic saturation magnetization
will decreases with the increase of temperature. Thus it
causes the motor gear and other local saturation degree rise.
The leakage reactance increases. Excitation current
intensity is increased, the reactive power loss increases, the
motor power factor will drop accordingly. Material
permeability will increase with the increase of temperature;
the reactance is reduced; power factor is improved.
Material iron loss has a corresponding decline with the
increase of temperature, it causes that the downward trend
of the efficiency was improved to a certain extent.
In the actual cases, the motor is not an isothermal body.
Temperature around the conductor is higher than the
ambient temperature. Therefore, in practical work, the
performance will be further down along the curve. At the
same time, because of the material thermal expansion,
contact distance decreases, the corresponding mechanical
loss increases, so that the motor efficiency declines.
REFERENCES
[1]
[2]
[3]
[4]
[5]
V. SUMMARY AND PROSPECT
[6]
Through the calculation and analysis, the results can be
obtained:
1. Motor copper loss and mechanical loss increased
with temperature, total loss increased.
2. The efficiency of the motor declines with the
increase of temperature. The curve approximated a
straight line.
[7]
[8]
[9]
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