Maigalisa YOHAMMA
maigalisa.yohanna@ogr.altinbas.edu.tr Electrical and Computer Engineering Altınbas University
Ekrem CILIZ
ekrem.ciliz@altinbas.edu.tr
Electrical and Computer Engineering Altınbas University
Oğuzhan TAVUKCU
oguzhan.tavukcu@ogr.altinbas.edu.tr Electrical and Computer Engineering Altınbas University
Assistant Professor Dr. Doğu Cağdaş ATİLLA
cagdas.atilla@altinbas.edu.tr Electrical and Electronics Engineering Altınbas University
Sadettin Faruk KURTULUŞ
sadettin.kurtulus@ogr.altinbas.edu.tr Electrical and Electronicsr Engineering Altınbas University
Yahya DEMİR
yahya.demir@ogr.altinbas.edu.tr Electrical and Electronics Engineering Altınbas University
MAKALE
ARGE Dergisi 25 Abstract - Today, the use of electric vehicles has an increasing demand levels than expected, so developed countries enhance their investments in this field. Motors used in electric vehicles can be classified as inner rotor and outer rotor motors. In this study, the efficiency which is one of the major parameters of the power train having a simpler structure is the main consideration and it is prioritized, the design of brushless direct current motor with outer rotor has been examined. ANSYS Electronics software was used as a design tool to enable the basic design of PMBLDCM with a specific layout. The article contains details of PMBLDCM with 36 slots and 40 pole combinations.
Keywords - ANSYS Electonics, Brussless Motor, Permanent Magnet, Windings,RMxprt, Motor Efficiency I. INTRODUCTION
Brushless DC motors have the properties of high performance, higher torque per volume, capability in high-speed applications and electronically driven commutation [1]. These benefits, when combined with programmed controls, have made BLDC motors very interesting. PMBLDCM is used in a wide range of applications such as washing machines, dryers, automotive industry, fans, pumps. These motors have different design variations depending on the specific application and requirements and can be designed by ANSYS Electronics Desktop tool; RMxprt. For the design consideration all physical parameters of the motor must be examined well. For the designated motor the design methodologies mentioned in [2].At the beginning of motor design, it should be known that how much power the motor should have, which rpm ranges require for higher efficiency, the properties of the material used, magnet properties and dimensions[3].
As a result of the optimization studies carried out in the continuation of this study, a PLMBLDCM design with a high efficiency between 350 and 700 rpm with a minimum torque of 25nm is examined.
II. DESIGN OF PMBLDC MOTOR
During the design process, the independent or “input” variables are usually dimensions, winding turns and properties of the magnet material. Dependent variables (output variables) are usually torque, current, efficiency, temperature rise, etc. Additive arguments are included in the design process, and mostly the values of the arguments are assigned values by iteration.
After the iterations if the performance is not sufficient, studies continue until the desired performance is achieved. Another method of design is fixing the dependent variables and deriving the independent variables using equations accordingly.
Fig.1.Rotor Design ANSYS RMxprt View
A. Rotor Design
In this part of the study, the appropriate outer diameter dimensions for the rim to be used while designing therotor were selected. As a result of the solved equations, the magnet was selected according to the magnetic field required.
Outer and inner diameter of proposed motor is magnet is selected as “Arnold_Magnetics_N35”
in the ANSYS program. After that, the Pole Embrace value seen in the program is 0.7961.
The program view of the rotor part of the motor is shown in Figure 1.
B. Stator Design
Stator dimensions were determined in combination with the previously determined rotor dimensions. Stator dimensions obtained as a result of the solutions of the existing equations Outer dimaeter and inner is 318 mm and 250 mm respectively. Additionally length of stator core is 30 mm and stacking factor is 0.95. Moreover slot type 3 for the design selected as. As mentioned before, the number of slots in stator is 36. The stator image formed as a result of the entered values is shown in Figure 2.
III. WINDING
As a result of the analysis and with the help of the mathematical flux formula, the winding combination was selected, where number of parallel branches 1, Number of condurctors per Slot 28, Number of Layers 2, Winding Type Whole Coiled, Number of wires per conductor 4, wire diameter 1.024 mm.
The net slot area of the design is 〖193.66 mm〗^2 and the stator slot fill factor is 60.6425%.
A. Wındıng Factor
The winding factor is the method of improving the generated RMS voltage in a three phase AC machines so that the torque and the output voltage does not consists any harmonics which reduces the efficiency of the machine. Winding Factor is defined as the product of distribution factor (Kd) and the coil span factor (Kc).The distribution factor measured the resultant voltage of the distributed winding regards concentrate winding and the coil span is the measure of the number of armature slots between the two sides of a coil. It is denoted by Kw [4].
B. Slot/Pole combination
36 slot and 40 pole combination has been selected in accordance with the desired torque and RPM values.
This pole combination winding factor is: 0.94521. At the same time this slot / magnet pole combination will have 360 cogging steps per turn.
IV. RESULTS AND ANALYSIS - A. Efficiency
The equation for calculating the efficiency is given below.
Here, [5]
n : Efficiency P_m : shaft power
P_fe : iron losses
P_pec : power electronics losses P_mk : mechanical losses
Fig.2.Rotor Design ANSYS RMxprt View Fig.3.Winding Design
(1)
B. Torque
The equation for the torque calculation of theresulting motor is as follows:
For the equation; [5]
T_e : permanent magnet bldc motor torque equation N : the number of turns in one phase
B_g : air gap flux density l : axial length of the motor
r : air gap radius
I_a : armature current
As a result of the analysis, the torque values given by the program are as in Figure 5.
C. INPUT CURRENT
The average current consumption of the motor was determined as 16.4644 A. Current values over RPM are shown in Figure 6.
Fig.4. Efficiency vs Speed Graphic
Fig.5. Output Torque vs Speed Graphic (2)
ARGE Dergisi 27
Fig.6. Input DC Current Graphics
TABLE I. General Analysis Results Fig.7.Power vs Speed Graphic
D. POWER
In Figure 7 Power vs Speed performance is shown. As seen in the graph, the motor reaches the highest power at 100 RPM. Considering that the efficient region for the design is between 400 and 700 RPMs, and the power corresponding to these values is on desired level.
E. ANALYSIS AND DISCUSSIONS
Featured results regarding the designed motoe are given in Table I.
NAME
Avarage input current Iron core loss Armature copper loss Output power
VALUE 16.4644 37.1211 43.5021 1500
UNITS Amper Watt Watt Watt
V. CONCLUSION
According to performance curves, desired levels of for the parameters are met by using ANSYS EDT software and an efficient motor design is completed.Simulation results show that the efficiency is 90% and above as given in the figures.While providing this efficiency, low average current values are also achieved. The motor has an average current of approximately 16 amps under load. The nominal power of the designed motor is calculated as 1.5 kW. Besides this, the maximum power of the motor is calculated as approximately 4 kW. In order to reach these data, 36/40 slot / pole combination was used as a result of derived equations. Winding factor of this combination is seen as 0.94521. The motor geometry is configured according to the properties and values of the selected magnets, using RMxprt software. Future studies will include analyzes with higher efficiency and different combinations in different rpm ranges.
VI. REFRENCES
[1] D.Ganselman, Brushless Permanent-Magnet Motor Desing, McGraw-Hill, 1994.
[2] Bin Zhang, Xiuhe Wang, Ran Zhang, Xiaolei Mou* M. Ehsan ‘Cogging Torque Reduction by Combining Teeth Notching and Rotor Magnets Skewing in PM BLDC with Concentrated Windings” IEEE Transaction on Electrical machines and systems,(IC EMS),03 VoU pp. 3189-3192.Feb.2009
[3] C. Carounagarane and S. Jeevananthan, “Generalized procedure for BLDC motor design and substantiation in MagNet 7.1.1 software,” in Computing, Electronics and Electrical Technologies (ICCEET), 2012 International Conference on, 2012.
[4] https://circuitglobe.com/winding-factor.html
[5] A. S. Çabuk, Ş. Sağlam and Ö. Üstün, “Investigation on efficiency of in-wheel BLDC motors for different winding structures,” Faculty of Engineering and Architecture of Gazi University, pp. 1975-1985, 2019.
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