DOCSLIB.ORG

Design of a Low-Mass High-Torque Brushless Motor for Application in Quadruped Robotics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Design of a Low-Mass High-Torque Brushless Motor for Application in Quadruped Robotics Design of a Low-Mass High-Torque Brushless Motor for Application in Quadruped Robotics by Niaja Nichole Farve B.S., Electrical Engineering, Morgan State University, 2010 Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering and Computer Science MASSACHUSETTS IN at the OF TECHNOLO( MASSACHUSETTS INSTITUTE OF TECHNOLOGY JUL 0 1 201 June 2012 LIBRARIE @ Massachusetts Institute of Technology 2012. All rights reserved. ARCHIVES Author ( .... ... ......................................... Depar en Uoofiectrical Engineering and Computer Science May 23, 2012 /1 ///i / Certified by ....................... .. ... ... .' I Jeff rey H. Lan Professor of Electrical Engineering and omputer Science Thesis Supervisor A ccepted by ................. .............. C r Dmeei A. Kolodziejski Chairman, Department Committee on Graduate Students 2 Design of a Low-Mass High-Torque Brushless Motor for Application in Quadruped Robotics by Niaja Nichole Farve Submitted to the Department of Electrical Engineering and Computer Science on May 23, 2012, in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering and Computer Science Abstract The Biomimetic Robotics Group is attempting to build the fastest quadruped robot powered by electromagnetic means. The limitations in achieving this goal are the torque produced from motors used to power the robot, as well as the mass and power dissipation of these motors. These limitations formulate the need for a low- mass high-torque low-loss motor. This thesis outlines the process of designing a permanent-magnet synchronous motor that meet the goals of the robot while mini- mizing the total mass. The motor designed from this thesis is compared to motors currently used by the Group when quantifying improvements made. In the process of achieving the goal, a design was formulated using fundamental electromagnetic prin- ciples. This design was then tested using finite element analysis. The final design was fabricated in house and wired by hand. The fabricated motor was tested to quantify key performance parameters such as peak cogging torque, peak motor torque, and thermal time constant under robot conditions. The motor designed by this thesis was able to produce more torque than the current motor being used by the Biomimetic Robotics Group, by a factor of 1.6, while decreasing the mass by 23%. A lower than desired packing factor was achieved since the motor was wired by hand resulting in a higher power dissipation and lower than expected motor torque. This design will be used in the quadroped robot after improvements are made to the cogging torque and packing factor. Thesis Supervisor: Jeffrey H. Lang Title: Professor of Electrical Engineering and Computer Science 3 4 Acknowledgments "Gratitude is a quality similar to electricity: it must be produced and discharged and used up in order to exist at all" ~William Faulkner I am beyond grateful for the never ending number of friends and family present in my life that encourage and inspire me everyday. Without which every mountain climbed would have been unfathomably higher. I wish I could name every person, but I think the list would exceed this thesis. I am especially grateful for my mother, role model, and best friend. You have pushed me to try even when success seemed impossible. You have always been there to help fix my problems and see the rainbow in the storm. I hope to one day become half the mother you have been to me. MIT would not have been as enjoyable without the man in my life that has been unbelievably understanding and encouraging, Omar. The friends I left at Morgan have also sporadicly brightened my weekends at MIT with their visits, reminding me of what great life long friends I have made. Likewise, new friends made here at MIT have helped to put things in perspective and gave my a small group where I feel like "I belong". Thank you for always being there to give me a reality check and helping me enjoy life. I don't think I could have possibly found a better adviser. Thank you Jeff for being beyond patient and spending so much of your precious time with my endless questions. I am also grateful to this institution as well as the RLE lab for giving my the chance to succeed in such a rigorous and challenging environment. I have grown in ways unimaginable due to my experience here. This work was funded by a Brookhaven National Laboratory Masters GEM Fel- lowship, and the DARPA grant 019719-001. The Biomemtic Robotics Group also provided funding and a tremendous amount of support. I am grateful for each of these resources and would not have been able to complete this thesis without this 5 support. 6 Contents 1 Introduction 11 1.1 Project Description .. ... ... ... ... ... .... ... ... 11 1.2 Robot Description .. ... ... ... ... ... .... ... ... 12 1.3 Application .. .... .... ... .... ... .... ... .... 13 1.4 First-Pass Comparison .... .... .... .... .... .... 13 1.5 Approach . .... ... .... .... ... .... ... .... ... 15 1.6 Challenges . ... ... ... ... ... ... ... .... ... ... 20 2 Formulation 23 2.1 Simplified Model .... .... .... .... ..... .... .... 23 2.2 Magnet Model. .. .. ... ... ... .. ... ... ... .. ... 23 2.3 Current Model .. ... ... ... .... ... ... ... ... ... 28 2.4 Combining models .. .... ..... .... .... .... .... 30 2.5 Design Parameters ..... ..... ..... ..... ..... ... 32 2.6 Optimization .... ... .... ... .... ... .... ... ... 36 3 Design 39 3.1 Materials .. ... ... ... .. ... ... ... ... .. ... ... 39 3.2 Dimensions .. ... ... ... ... .. ... ... ... .. ... .. 39 3.3 Mass and Rotor Inertia Calculations ... ... ... ... ... ... 43 3.4 Resistance and Inductance Calculations .. .... .... ... .... 43 3.5 Finite Element Analysis .... .... ..... .... .... .... 45 7 4 Fabrication 49 4.1 Hardware ................................. 49 4.1.1 Laminations .. ..... ..... .... ..... ..... .. 49 4.1.2 M agnets ... .... ..... ..... .... ..... .... 54 4.1.3 W ire ...... ........ ........ ....... ... 54 4.2 Procedure ..... ..... ..... ..... ..... ..... ... 54 4.2.1 Winding Process ... ...... ..... ...... ..... 55 4.2.2 Magnet Alignment . ..... ..... .... ..... .... 55 4.2.3 Encasing Stator and Rotor ..... ...... ..... .... 58 5 Testing 61 5.1 Resistance ... ..... ..... ..... ..... ..... ..... 61 5.2 Inductance .... .. ... .... .... ..... .... .... 63 5.3 Back EMF. .... .. ..... ..... ..... ..... ... 64 5.4 Cogging Torque ... ..... .... .... .... .... .... .. 67 5.5 Thermal Performance. .. .... .... .... .... ..... ... 68 5.6 R esults ...... ...... ....... ...... ...... .... 71 6 Conclusion 75 6.0.1 Future Work. ..... ..... .... ..... ..... .. 76 A MATLAB Script 79 B FEA Settings 91 B.1 COMSOL Setup ..... ..... ..... ..... ..... ..... 91 B.2 COMSOL Settings ....... ...... ...... ...... ... 92 C Cogging Torque Experimental Data 95 C.1 Measured Data . ...... ....... ...... ...... .... 95 D Thermal Resistance Experimental Data 97 D.1 Measured Data . ... ... ... ... ... ... .... ... ... 97 8 List of Figures 1-1 MIT Cheetah Robot conceptual design. ... ..... ..... .... 12 1-2 Power dissipation versus mass trade off curve for doubly-wound motor near 2400 W. Each data point represents the performance of one motor design ... .... .... .... .... .... .... .... .... 16 1-3 Power dissipation versus mass trade-off curve for permanent-magnet motor at 40 Nm over a wide power range. Each data point represents the performance of one motor design. .... .... .... .... 16 1-4 Power dissipation versus mass trade-off curve for permanent magnet motor near 2400 W at 40 Nm. This figure is an expansion of Figure 1-3. ....... ... .................................... 17 1-5 Power dissipation versus mass trade-off curve for permanent magnet motor near 2400 W at 50 Nm. .. .... .... .... .... ... 17 1-6 Power dissipation versus mass trade-off curve for permanent-magnet motor at 50 Nm over a wide power range. Each data point represents the performance of one motor design. .. .... ..... ..... 18 1-7 Fundamental motor layout . .... ..... ..... ..... .... 18 1-8 Example of motor flux lines .... .... .... .... .... ... 19 1-9 Design approach flow chart. .... ...... ...... ....... 21 2-1 Magnet only model for the designed motor. ... ... ... .... .. 24 2-2 Current only model for the designed motor. ... .... ... .... 29 2-3 Complete model for the designed motor. ... ... ... ... ... 31 2-4 Resistance Calulation .. ... ... .... ... ... ... ... ... 35 9 2-5 Chart of all designed dimensions. ................. 37 3-1 Final motor design front view illustrated with MATLAB. .... 40 3-2 Final motor design side view illustrated with MATLAB..... 41 3-3 Hyperco 50 B-H curve used as a design input. .......... 42 3-4 Magnetic field lines for designed motor depicted with COMSOL. 46 3-5 Motor torque profile data collected from COMSOL. ...... 46 3-6 Cogging torque derived through FEA ......... ...... 47 4-1 Complete motor 2D image. ....... ... 50 4-2 Complete motor of 3D image...... 51 4-3 Drawing of designed stator ... .... .... 52 4-4 Drawing of stator zoomed in. ..... ... 53 4-5 Phase A beginnging the wiring process . .. 56 4-6 Phase B beginnging the wiring process . ... 56 4-7 Phase C beginnging the wiring process ... 56 4-8 Winding Process ............ .. .. 57 4-9 Magnet and Rotor ........... .. 58 4-10 Complete Motor ............. .. 59 5-1 Moment arm addition made to the motor ... ... 62 5-2 Measured back EMF from experiments ......
Load more

Recommended publications
  • Motor Actuators Basics
    Motor Actuators Basics - 1 - Note: All specifications and other information are not guaranteed and are subject to change without notice. Prior to any new usage of JE motor actuators it is recommended to contact Johnson Electric. All information below and content of links are subject to the disclaimer of the Johnson Electric website - 2 - Contents Overview ....................................................................................................................................................................... 4 Classification ............................................................................................................................................................. 5 DC Motors ................................................................................................................................................................. 6 Universal Motors ....................................................................................................................................................... 7 BLDC Motors ............................................................................................................................................................. 8 Synchronous Motors ................................................................................................................................................. 9 Stepper Motors ........................................................................................................................................................ 10 Shaded
    [Show full text]
  • Cogging Torque Reduction in Brushless Motors by a Nonlinear Control Technique
    Article Cogging Torque Reduction in Brushless Motors by a Nonlinear Control Technique Pierpaolo Dini and Sergio Saponara * Department of Information Engineering, University of Pisa, Via G. Caruso 16, 56127 Pisa, Italy; [email protected] * Correspondence: [email protected] Received: 1 April 2019; Accepted: 9 June 2019; Published: 11 June 2019 Abstract: This work addresses the problem of mitigating the effects of the cogging torque in permanent magnet synchronous motors, particularly brushless motors, which is a main issue in precision electric drive applications. In this work, a method for mitigating the effects of the cogging torque is proposed, based on the use of a nonlinear automatic control technique known as feedback linearization that is ideal for underactuated dynamic systems. The aim of this work is to present an alternative to classic solutions based on the physical modification of the electrical machine to try to suppress the natural interaction between the permanent magnets and the teeth of the stator slots. Such modifications of electric machines are often expensive because they require customized procedures, while the proposed method does not require any modification of the electric drive. With respect to other algorithmic-based solutions for cogging torque reduction, the proposed control technique is scalable to different motor parameters, deterministic, and robust, and hence easy to use and verify for safety-critical applications. As an application case example, the work reports the reduction of the oscillations for the angular position control of a permanent magnet synchronous motor vs. classic PI (proportional-integrative) cascaded control. Moreover, the proposed algorithm is suitable to be implemented in low-cost embedded control units.
    [Show full text]
  • Energy Harvesting Using AC Machines with High Effective Pole Count,” Power Electronics Specialists Conference, P 2229-34, 2008
    The Pennsylvania State University The Graduate School Department of Electrical Engineering ENERGY HARVESTING USING AC MACHINES WITH HIGH EFFECTIVE POLE COUNT A Dissertation in Electrical Engineering by Richard Theodore Geiger 2010 Richard Theodore Geiger Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2010 ii The dissertation of Richard Theodore Geiger was reviewed and approved* by the following: Heath Hofmann Associate Professor, Electrical Engineering Dissertation Advisor Chair of Committee George A. Lesieutre Professor and Head, Aerospace Engineering Mary Frecker Professor, Mechanical & Nuclear Engineering John Mitchell Professor, Electrical Engineering Jim Breakall Professor, Electrical Engineering W. Kenneth Jenkins Professor, Electrical Engineering Head of the Department of Electrical Engineering *Signatures are on file in the Graduate School iii ABSTRACT In this thesis, ways to improve the power conversion of rotating generators at low rotor speeds in energy harvesting applications were investigated. One method is to increase the pole count, which increases the generator back-emf without also increasing the I2R losses, thereby increasing both torque density and conversion efficiency. One machine topology that has a high effective pole count is a hybrid “stepper” machine. However, the large self inductance of these machines decreases their power factor and hence the maximum power that can be delivered to a load. This effect can be cancelled by the addition of capacitors in series with the stepper windings. A circuit was designed and implemented to automatically vary the series capacitance over the entire speed range investigated. The addition of the series capacitors improved the power output of the stepper machine by up to 700%.
    [Show full text]
  • Design Optimization and Analysis of an Outer-Rotor Direct-Drive Permanent-Magnet Motor for Medium- Speed Electric Vehicle
    Article Design Optimization and Analysis of an Outer-Rotor Direct-Drive Permanent-Magnet Motor for Medium- Speed Electric Vehicle Yuan Yuan 1,*, Wenjun Meng 1, Xiaoxia Sun 1 and Liyong Zhang 2 1 School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China; [email protected] (W.M.); [email protected] (X.S.) 2 Great Wall Motor Company Limited, Baoding 071000, China; [email protected] * Correspondence: [email protected] Received: 18 February 2019; Accepted: 20 March 2019; Published: 4 April 2019 Abstract: At present, it is the conventional inner rotor motor instead of the internal combustion engine that is adopted by most electric cars. However, compared to the traditional centralized driving pattern, cars adopting a distributed direct driving pattern have higher drive efficiency and more stable handling. Given this background, a kind of direct-drive outer rotor motor with 40 poles and 42 slots applied for middle or low speed electric cars was designed. The core of this study included the electromagnetic analysis and structural design of the motor. Firstly, the material and dimension parameters of the stator and rotor were selected and calculated by the traditional method. The air-gap length and pole-arc coefficient were optimized using an RMxprt module, which was developed using the equivalent magnetic circuit method. Then, a two-dimensional finite- element model was established using ANSYS Maxwell. The magnetic field and torque characteristics of the model were then analyzed. Results show that the design of the motor is reasonable. In addition, a method for reducing the torque ripple was proposed and verified by simulation.
    [Show full text]
  • Stepper Motors Stepper Motor
    Motor Types TI Precision Labs – Motor Drivers Presented and prepared by Dalton Ortega 1 Brushed-DC Motors Brushed – DC motor commutation Bidirectional brushed motor driver Permanent magnets VM Motor windings OFFON OFFON Commutator OUT1 OUT2 OUT1 OFFON OFFON OUT2 Brushes ForwardReverse Drive Brushed-DC motor tradeoffs, common applications • Basic function: move a load in one direction only or both directions. • Advantages: – Low cost solution – Current control not required – Easy to control • Disadvantages – Brushes wear out – Loud, sparking, may have EMI concerns – Requires external sensors for speed/position control 4 Brushless-DC Motors Brushless-DC motor construction (Cont.) Inner Rotor (Conventional) Outer Rotor (Outrunner) Permanent magnet Coil windings Smaller construction (compact) Larger construction Better heat dissipation Worse heat dissipation Lower rotor inertia Higher rotor inertia Quick speed change applications Constant speed applications High torque and speed Higher torque at low rpm High cogging torque Low cogging torque Harder to wind the coils Easier to wind the coils High performance magnets Lower performance magnets Servos, actuators, pumps Fans, hard disk, printers Brushless-DC motor winding connections Wye (Y) Winding Delta (∆) Winding Star connection Normally more efficient Normally less efficient Less resistive losses More resistive losses Immune to parasitic currents Parasitic currents can circulate Higher torque at low speed Lower torque at low speed Lower top speed Higher top speed Most common Both are driven
    [Show full text]
  • Design Optimization and Analysis of an Outer-Rotor Direct-Drive Permanent-Magnet Motor for Medium-Speed Electric Vehicle
    Article Design Optimization and Analysis of an Outer-Rotor Direct-Drive Permanent-Magnet Motor for Medium-Speed Electric Vehicle Yuan Yuan 1,*, Wenjun Meng 1, Xiaoxia Sun 1 and Liyong Zhang 2 1 School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China; [email protected] (W.M.); [email protected] (X.S.) 2 Great Wall Motor Company Limited, Baoding 071000, China; [email protected] * Correspondence: [email protected] Received: 18 February 2019; Accepted: 20 March 2019; Published: 4 April 2019 Abstract: At present, it is the conventional inner rotor motor instead of the internal combustion engine that is adopted by most electric cars. However, compared to the traditional centralized driving pattern, cars adopting a distributed direct driving pattern have higher drive efficiency and more stable handling. Given this background, a kind of direct-drive outer rotor motor with 40 poles and 42 slots applied for middle or low speed electric cars was designed. The core of this study included the electromagnetic analysis and structural design of the motor. Firstly, the material and dimension parameters of the stator and rotor were selected and calculated by the traditional method. The air-gap length and pole-arc coefficient were optimized using an RMxprt module, which was developed using the equivalent magnetic circuit method. Then, a two-dimensional finite-element model was established using ANSYS Maxwell. The magnetic field and torque characteristics of the model were then analyzed. Results show that the design of the motor is reasonable. In addition, a method for reducing the torque ripple was proposed and verified by simulation.
    [Show full text]
  • Design, Analysis of the Location and Materials of Neodymium Magnets on the Torque and Power of In-Wheel External Rotor PMSM for Electric Vehicles
    energies Article Design, Analysis of the Location and Materials of Neodymium Magnets on the Torque and Power of In-Wheel External Rotor PMSM for Electric Vehicles Andrzej Łebkowski ID Department of Ship Automation, Gdynia Maritime University, 81-225 Gdynia, Poland; [email protected] Received: 24 July 2018; Accepted: 28 August 2018; Published: 31 August 2018 Abstract: The technology of mounting electric direct drive motors into vehicle wheels has become one of the trends in the field of electric vehicle drive systems. The article presents suggestions for answering the question: How should magnets be mounted on the External Rotor Permanent Magnet Synchronous Machine (ERPMSM) with three phase concentrated windings, to ensure optimal operation of the electric machine in all climatic and weather conditions? The ERPMSM design methodology is discussed. Step by step, a method related to the implementation of subsequent stages of design works and tools (calculation methods) used in this type of work are presented. By means of FEM 2D software, various ERPMSM designs were analyzed in terms of power, torque, rotational speed, cogging torque and torque ripple. The results of numerical calculations related to variations in geometric sizes and application of different base materials for each of ERPMSM machine components are presented. The final parameters of the motor designed for mounting inside the wheel of the vehicle are presented (Power = 53 kW, Torque = 347 Nm; Base speed = 1550 RPM), which correspond to the adopted initial assumptions. Keywords: in-wheel motor; hub-motor; outrunner PMSM; electric vehicle; battery electric vehicle 1. Introduction The reduction of energy consumption from fossil fuels is an inspiration for many designers in undertaking the effort of designing new structures used in electric vehicles.
    [Show full text]
  • Design and Performance Comparison of Four-Pole Brushless Dc Motors with Different Pole/Slot Combinations
    The International Journal of Energy & Engineering Sciences, 2018, 3 (3) 69-78 69 ISSN: 2602-294X - Gaziantep University DESIGN AND PERFORMANCE COMPARISON OF FOUR-POLE BRUSHLESS DC MOTORS WITH DIFFERENT POLE/SLOT COMBINATIONS Cemil OCAK Vocational College of Technical Sciences, Gazi University, Ankara, Turkey. [email protected] ABSTRACT When the design process of the brushless motor is examined, attention must be paid to the correct choice of magnet material, internal or external rotor structure and the choice of core and winding structure. In addition to all these, the number of phases, the number of rotor poles, and the choice of slots configurations depending on them also have great importance. For this reason, to achieve optimum design, it is necessary to analyze all possible designs with different pole/slot configurations that can accommodate similar power and speed expectations. In this study, three different designs have been realized with different pole/slot configurations for four- pole, internal rotor brushless DC motors, which are frequently used in many different applications today. Designed motors have been analyzed with Finite Element Method to obtain the cogging torque, efficiency and active material costs. All motors that are analyzed have 100 W, 3000 rpm, 4/6, 4/12 and 4/15 pole/slot configurations respectively. Keywords: brushless DC motor, pole/slot combinations, efficiency, internal rotor. 1. INTRODUCTION Although the moment-speed characteristic is linear in DC motors, the most important disadvantage of this type of motors is the realization of excitation by using brush and collector assembly. Due to the mechanical commutation, the motor requires frequent maintenance.
    [Show full text]
  • Modeling and Analysis of High Torque Density Transverse Flux Machines
    Modeling and Analysis of High Torque Density Transverse Flux Machines for Direct-Drive Applications A Dissertation Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Iftekhar Hasan December, 2017 i Modeling and Analysis of High Torque Density Transverse Flux Machines for Direct-Drive Applications Iftekhar Hasan Dissertation Approved: Accepted: Adviser Interim Department Chair Dr. Yilmaz Sozer Dr. Joan Carletta Committee Member Dean of the College Dr. Malik Elbuluk Dr. Donald P. Visco Jr. Committee Member Dean of the Graduate School Dr. J. Alexis De Abreu Garcia Dr. Chand Midha Committee Member Date Dr. Alper Buldum Committee Member Dr. Kevin Kreider ii ABSTRACT Commercially available permanent magnet synchronous machines (PMSM) typically use rare-earth-based permanent magnets (PM). However, volatility and uncertainty associated with the supply and cost of rare-earth magnets have caused a push for increased research into the development of non-rare-earth based PM machines and reluctance machines. Compared to other PMSM topologies, the Transverse Flux Machine (TFM) is a promising candidate to get higher torque densities at low speed for direct-drive applications, using non-rare-earth based PMs. The TFMs can be designed with a very small pole pitch which allows them to attain higher force density than conventional radial flux machines (RFM) and axial flux machines (AFM). This dissertation presents the modeling, electromagnetic design, vibration analysis, and prototype development of a novel non-rare-earth based PM-TFM for a direct-drive wind turbine application. The proposed TFM addresses the issues of low power factor, cogging torque, and torque ripple during the electromagnetic design phase.
    [Show full text]
  • Cogging Torque Measurement, Moment of Inertia Determination and Sensitivity Analysis of an Axial Flux Permanent Magnet AC Motor P.W
    Cogging Torque Measurement, Moment of Inertia Determination and Sensitivity Analysis of an Axial Flux Permanent Magnet AC motor P.W. Poels DCT 2007.147 Traineeship report Traineeship performed at the Charles Darwin University, Darwin, Australia Coach(es): dr. ir. F. de Boer G. Heins Supervisor: dr.ir. M. Steinbuch Technische Universiteit Eindhoven Department Mechanical Engineering Control Systems Technology Group Eindhoven, June, 2008 ii Abstract Many technical applications require a smooth torque. An axial flux permanent magnet (PM) AC motor is used to achieve this with control methods. Required are motor param- eters, such as the moment of inertia. This parameter is determined by calculation with help of the CAD drawings. To verify the result, an experimental setup is designed. The resulting difference of 6.6% between the calculated and experimental determinded value of the moment of inertia is explained with the help of a sensitivity analysis. One of the properties of the type of motor used to achieve smooth torque is the presence of cogging torque. To compensate for cogging torque, this parameter needs to be measured. To be able to do this, a measurement method is designed. To explain the resulting RMSerror a sensitivity analysis of the calibration method is made. This is done theoretically and verified experimentally. The remaining RMSerror of 0.8 − 1.5% is caused by the current sensor and control errors. iii iv Samenvatting Voor vele technische toepassingen is een constant koppel vereist. Door enkele regel me- thodes toe te passen op een axiale flux permanente magneet (PM) AC motor wordt dit bereikt. Hiervoor is het nodig om de motor parameters te weten, zoals het massatraaghei- dsmoment.
    [Show full text]
  • Brushless Direct Current Electric Motor Design with Minimum Cogging Torque
    Proceeding of International Conference on Electrical Engineering, Computer Science and Informatics (EECSI 2014), Yogyakarta, Indonesia, 20-21 August 2014 Brushless Direct Current Electric Motor Design with Minimum Cogging Torque Hery Tri Waloyo Mechanical Engineering, Post Graduate Program Muhammad Nizam Sebelas Maret University Mechanical Engineering, Post Graduate Program Surakarta, Indonesia Sebelas Maret University [email protected] Surakarta, Indonesia [email protected] Inayati Chemical Engineering Department Sebelas Maret University, Surakarta, Indonesia [email protected] Abstract— Cogging torque is one of the factors that influence Designing a BLDC motors need to pay attention to some electric motor efficiency. Many methods have been used to aspects and the most important is its efficiency. One factor reduce the cogging torque. One of the methods is the which affecting its efficiency is the existence of cogging determination of the number of slots and poles fraction. This torque. Large cogging torque causes vibration and noise which study was intended to determine the number of slots and poles reduces the efficiency. Axial motor with variation on the fraction to get a minimum of cogging torque. Research was done number of poles will affect the asymmetry of the back-EMF, by ANSYS software. By varying the number of slots and poles, cogging torque, torque and reduce the electromagnetic torque the data cogging torque and torque ripple were observed. It was ripple [3]. Adding an additional gap can reduce cogging torque found that the lesser difference between the number of slots and and electromagnetic torque ripple. After reaching a maximum poles produced lower cogging torque. More numbers of slots gap addition, the cogging torque will be at steady state [4].
    [Show full text]
  • 873. Cogging Torque and Torque Ripple Reduction of a Novel Exterior-Rotor Geared Motor
    873. Cogging torque and torque ripple reduction of a novel exterior-rotor geared motor Yi-Chang Wu 1, Yi-Cheng Hong 2 National Yunlin University of Science & Technology, Yunlin, Taiwan, R. O. C. E-mail: [email protected] , [email protected] (Received 28 June 2012; accepted 4 September 2012) Abstract. The reduction of cogging torque and torque ripple in permanent-magnet motors to suppress the vibration and acoustic noise is a major concern for motor designers. This study presents a novel exterior-rotor geared motor which integrates a brushless permanent-magnet (BLPM) motor with an epicyclic-type gear reducer to form a compact structural assembly without extra transmitting elements. One of the special features of the geared motor lies in the gear-teeth of the epicyclic-type gear reducer merged with the stator of the BLPM motor. The gear-teeth serve as the interfacial medium to connect the BLPM motor with the epicyclic-type gear reducer, which provides functions not only for transmission to achieve a desired speed ratio, but also effectively reduce the cogging torque and torque ripple of the geared motor. Five shape models of pole shoes with different values of the shoe depth and the shoe ramp are presented to effectively reduce the cogging torque and the torque ripple. With the aid of the finite-element analysis, shape model III of the geared motor performs better than the existing BLPM motor on the cogging torque with 87 % decreasing and the torque ripple with 23 % decreasing. Such a unique characteristic of the geared motor is of benefit to the widely applications on accurate motion and position control systems.
    [Show full text]