Üniversal motorun benzetişim ve tasarımı
The Simulation and design methods of universal motor
Yazar: MURAT YILMAZ
Danışman: PROF. DR. R. NEJAT TUNCAY
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 1999
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering
Dizin: Benzetim = Simulation ; Motorlar = Motors ; Tasarım = Design ; Üniversal motorlar = Universal motors

Özet:
ÖZET Ülkemizde ve dünyada milyonlarca adet üretilen universal motorlar ev aletleri gibi değişken hızlarda çalışmaları gereken tüketici uygulamalarında tahrik makinası olarak kullanılmaktadır. Günümüzde toplum refah düzeyinin artması beyaz eşyaya olan talepte büyük bir artış doğurmuştur. Bunun sonucu olarak da diğer elektrik makinalarına göre, düşük maliyetle çok yüksek hızlara ulaşan universal motorların önemi artmıştır. İster donanım, ister yazılım olsun bilgisayar dünyasındaki hızlı ve baş döndürücü gelişmeler, bütün mühendislik alanlarında olduğu gibi Elektrik Mühendisliğinde de inanılmaz kolaylıklar ve imkanlar sağlamaktadır. Bu tez çalışmasında bu imkanlardan yararlanılarak universal motorun benzetişimi ve tasarımı bilgisayar ortamında gerçekleştirilmiştir. Öncelikli olarak universal motorun yapısı, çalışma prensibi ve eşdeğer devre modeli anlatılmıştır. Örnek alınan çeşitli motorlara direnç, endüktans, yük performans, boşta çalışma ve kayıp deneyleri uygulanarak motorların bilinmeyenleri elde edilmiştir. Deneyler ve sonlu elemanlar paket programı Magnet5.0 dan elde edilen sonuçlar kullanılarak, yüksek performanslı sayısal ve grafiksel hesaplamalar için geliştirilen Matlab-Simulink paket programında motor benzetişimi gerçekleştirilmiştir. Simulink sonuçlan, bilgisayar kontrollü motor test düzeneği olan Magtrol sonuçlan ile karşılaştırılarak elde edilen sonuçların birbirine yakınlığı görülmüştür. Tez çalışmasında son olarak görsel programlama dili Visual Basic paket programı yardımı ile universal motorun tasarımı gerçekleştirilmiştir. Tasarım sırasında kullanılan tablolar ve grafikler Senur Elektrik Motorlar A.Ş. tarafından üretilen motorlara uygulanan çeşitli deneyler sonucu elde edilmiştir. Literatür çalışması ve ters mühendislik yaklaşımı ile tasarımın temelini oluşturan denklemler elde edilerek, Visual Basic ortamında bu denklemlerin çözümü sağlanmıştır. 901 XV111

Abstract:
THE SIMULATION AND DESIGN METHODS OF UNIVERSAL MOTOR SUMMARY The aim of this thesis is, to present the simulation, design and experiments of the universal motor for speeds up to 40000 rpm. In order to reach to this aim, the subjects are handled in the following sequence; 1. Universal motors are introduced and the description of their characteristics are given. The armature reaction and the commutation problems are explained. 2. Development of the equivalent circuit and mathematical model for universal motor considering brush shift. Figure 2.7 shows the equivalent circuit of the universal motor. 3. Various universal motors are tested. The test motors are manufactured Senur Elektrik Motorları A.Ş. as dry and wet-dry type vacuum cleaner motors. The two dimensional geometry for wet-dry vacuum cleaner's motof is shown in Figure 1. 4. Various test motors are designed, manufactured and tested. Performance tests are conducted by using a MAGTROL test system. The input power, input current, output power, output torque and efficiency of the motors are recorded for speeds up to 40000 rpm. The information on Magtrol test system and the measured performance values are presented in Chapter 4. 5. MATLAB with SIMULINK packet program is introduced. Mathematical model of universal motor is formed and simulation results are obtained in Simulink environment. The developed computer programme is called UMSIM. 6. The experimental test results are compared with the simulated ones. It is seen that the experimental and theoretical values are in good agreement. 7. General design concepts and design procedures of universal motors are introduced. Main construction of the motor, main dimension equation, size determining factors are defined. XIX8. In order to develop a comprehensive design programme, a design methodology is formed and applied by using the VISUAL BASIC language. Figure 1. The cross section of the wet-dry vacuum cleaner's motor. Operational Principles of Universal Motor: The name universal motor comes from the ability to operate on both direct and alternating current. The universal motor will be running when is connected to an AC source of supply. The direction of the torque is determined by both the field polarity and the direction of the current through the armature. Since the same current passes through the field coils and armature winding, it follows that the AC reversals from positive to negative, and vice versa, will simultaneously affect the field polarity and the direction of the current in the armature conductors. Therefore the unidirectional torque is produced. Figure 2 represents an universal motor in which the torque produces counter-clockwise rotation for both directions of current flow. In figure 2a the top and bottom terminals are positive and negative and upper and lower poles are north and south, respectively. When the polarities of the line terminals reverse. As they would in second half of an AC cycle, the upper and lower poles become south and north, respectively. The current through the armature will now be from left to right, and the resulting crosses and dots in the conductors will therefore change. XXFigure 2b represents these conditions, from which it can be seen that the armature will continue to rotate counter-clockwise. (a) Current directions and polarities for first half of cycle (bj Current directions and polarities for second half of cycle Figure 2. Elementary universal motor illustrating that the direction of rotation is unchanged when the line polarity is reversed. Speed-Load Characteristics and Types of Universal Motors: Universal motors are characterezid by their ability to operate, with substantially the same performance, on direct as well as alternating current of frequencies up to 60 Hz. These motors are series wound and have series characteristics on both direct and alternating current. No-load speeds are high, sometimes well over 50000 rpm, but the armatures are designed so that they will not be damaged at these speeds. They are usually designed for foil load operating speeds of 6000 to 20000 larger power ratings, and up to 35000 or more in smaller power ratings. At higher speeds better universal characteristics, that is nearly the same performance characteristics on both direct and alternating current, can be obtained. Universal motors are generally custom-built for specific application and are very often sold as parts rafter than as complete motors. There used to be two major types of universal motors, non-compensated and compensated, but the latter has now all but disappeared. The non-compensated XXImotor usually is built with concentrated or salient poles. The speed-torque characteristic of a non-compensated motor is given in figure 3. Compensated motors have a distributed laminated field structure similar to the AC induction motor. The compensated universal motor has better universal characteristics than the non compensated universal motor. The non-compensated universal motor is less expensive and simpler in construction so it is more generally used for these reasons. Torque Figure 3. Typical speed-torque curve of a non-compensated universal motor. It is to be noted that with either type, the speed drops off rapidly with an increase in load and increases with decrease in load. This characteristic is most desirable in vacuum cleaner, for if the cleaner is used under conditions which decrease the volume of air handled, the load on the motor decreases. This decrease in motor load is acompained by increased motor speed and increased vacuum, so that the cleaner will actually handle more air than it would if a constant motor were used. Likewise, this characteristic of speeding up on light loads is very desirable in the case of portable drills, for the motor will drive small drills at high speed and larger drills at a lower speed. XXllApplications of Universal Motors: These motors are used in a considerable number of applications requiring all sorts of operating characteristics. In some, the actual motor speed is the load speed, a good example being a vacuum cleaner. In others, the load speed, through a gear train, is reduced considerably; good examples of this practice are drink mixers, wood mixers and portable drills. In order to illustrate the wide range of applications of universal motors a list of those more frequently used is given in Table 1. Table 1. Common applications of universal motors. Simulation of Universal Motor by SIMULINK: SIMULINK is a program for simulating dynamic systems. It has two phases of use; model definition and model analysis. A typical session starts by either defining a model or recalling a previously defined model, and then proceeds to analysis of that XXUlmodel. In practice, these two steps are often performed iteratively as the model as the model designer creates and modifies a model to achieve the 4esired behaviour. To facilitate model definition, Simulink adds a new class of windows called block diagram windows. In this windows, models are created and edited principally by mouse driven commands. Part of mastering Simulink is to become familiar with the manipulation of model components within these windows. After you define a model, you can analyse it either by choosing options from the Simulink menus or by entering commands in Matlab's command window. The progress of a simulation can be viewed while the simulation is running, and the final results can be made available in the Matlab workspace when a simulation is complete. In chapter 4 of this thesis a mathematical model of universal motor is formed and simulation results are obtained in Simulink environment. The developed Simulink programme is called UMSEVi The block diagram of the Simulink model is depicted in Figure 4. EnSı5>- ei i » Figure 4. The block Diagram of the Simulink model. XXIVThe experimental test results are compared with with simulated ones. It is seen that the experimental and theoretical values are in good agreement. Comparing results are given in chapter 6. Design Methodology for Universal Motor: Universal motors are series wound and have series motor characteristics. They generally found applications in small dimension. Then no load speeds are very high. Therefore, motor design is a multi-disciplinary subject. It involves not only electromagnetic design but also selection of engineering materials, component specifications, and production techniques. Commutation and mechanical hardness the most important problems. General design concepts of universal motor and design procedures are introduced in the seventh chapter. Main construction of the motor, main dimension equation, size determining factors are also defined. In order to develop a comprehensive design programme, a design methodology is formed and applied by using the VISUAL BASIC language. The flow diagram and results of the Visual Basic programme are given in the final chapter. XXV