Yeni Bir Gerilim Ara Devreli Evirici İle Derin Kafesli Çelik Rotorlu Asenkron Motorun Modellenmesi Ve Denenmesi

Abstract

Bu tezin ilk kısımlarında evirici çıkış gerilim dalgasında harmonikleri azaltmak amacınla, darbe genlik ve genişlik modülasyonunu birlikte içeren yeni dalga şekilleri önerilmiştir. önerilen çıkış gerilim dalgasında toplam harmonik distorsiyonu % 7.7 ye düşürülmüştür. Çalışmanın ikinci kısmında yeni bir gerilim ara devreli evirici tasarımı yapılarak gerçekleştirilmiştir. Bu evirici sistemle kütle çelik ve derin bakır kafesli çelik rotorlu asenkron motorlar beslenmiştir. Gerçekleştirilen eviricide optimum bir çıkış gerilim dalgası seçilerek, asenkron motor hız denetiminde düşük devirlerde çeşitli problemlere neden olan 6 inci harmonik momentlerinin yok olması sağlanmıştır. Tezin son kısmında derin bakır kafesli çelik rotorlu asenkron motor için bir eşdeğer devre geliştirilmiştir. Bu eşdeğer devre kuramsal olarak çözülmüştür. Geliştirilen eşdeğer devrenin deneysel sonuçlarla uygunluğu görülmüştür. önerilen yeni eşdeğer devre modelinin bu tür motorların analizinde başarı ile kullanılabileceği anlaşılmaktadır.

in this thesis, the inverter output waveforms are studied and the new optimum inverter-output vaveforms which have minimum harmoni es för various voltage values are developed.Additionalln a new de linked inverter drive sBstem is designed and realised, This drive sjjstem isemployed in scalar speed control through voltage and frequenc*j changing schemes. As an application, a steel secondarg three phase induction motor which has deep Cu squirrel cage embeddet in the rotor are handled. A new theoretical model f ör this tHpe of motor is proposed and used, in order to obtain theoretical performance values. in the later chapters of this studtj. The experimentel investigation of this motor is completed and the theoretical and experimenteal values are compared. it is shovn that these values are in good agreement. As it is knovm that, inverters produce square wave outputs which have various amplitute and frequencH- These outputs are modified in various methods. Öne of which is pulse width modulation method. in this studg, better vaveforms are investigated and new optimum vaveshapes are proposed. Thes© proposed vaveforms, which have three voltage levels and emplon PWM, are presented in figüre 1. For thes© waveforms, the width of the pulses are increased proportionallgr vith a constant angle of 6. At the same -time, the quarter-wave sHrometrH is sustained, therefore- even harmonies are inherently eliminated. The Fourier analnsis of these waveforms gields the folloving values f ör a. and b waves in Fi g. i. Th© Fourier coefficient för wave a is, vi A. m. p. L2N2B J0 Z = 3 e r a.p.k ç.0.s 6 where N = number of effective turns, k = transverse edge effecfc factor.m - number of phases, p = resistivitg 2p = number of poles, Ç = pole pich, A = 4.59 a constant and 0= phase angle of rotor impedance. The fcorques produced bH the deep squirrel cage and solid-rotor are calculated seperately and presented in Fiğ. 6. in order to evaluate the success of the theoretical studg. The experimental results are presented on the same figüre. The experimental and theoretical values are in good agreement. it is seen that the model vhich takes the deep squirrel cage in solid rotor machine is successf ull_r enables to calculate the perfomance values. 1.5 l l l I j j 1 } j 1 *" '*"."!»._ - i KT^^IIZIZIIIZI t heo ret i c al ^... ____^ ______ '"'.'.""-.. experimental ""'.Ss" '' r**. "X ol-M l l l Iztıoz: 0 N l600 i Figüre 6. The theoretical and experimental torque-speed of the solid-rotor deep-cage values induction motor. xi performance values are recorded. In order to calculate the theoretical performance of the drive system, a mathematical model for the motor is developed. This mathematical model does not onla take the solid-rotor structure but also takes the deep-cage which is embedded in the rotor. It is known that the generalised machine theory gives the penetration depth in steel as 5, 0 2B L in this equation ; 0 = flux per pole, B = 1. 8T saturation level for steel, L = length of the rotor. In order to take the deep cage effect, a dependent source is inserted in the rotor network of the equivalent circuit. When induction machine is starting, the rotor current frequency is 50 Hz therefore flux could not penetrate down to the cage and machine acts as solid rotor machine. However, when speed gets up, the rotor current frequency becomes lower and penetration depth becomes higher, and additional flux linkages the deep cage. For high speeds, rotor current flows in the cage and produces additional torques. A better torque-speed curves are obtained in high speed low slip region. The equivalent circuit of the induction motor which has deep rotor cage is given in Fig.S. Figure 5. The equivalent circuit of a solid rotor induction motor with deep rotor cage. The rotor impedance is given as, Z, A. m. p. L2N2B J0 Z = 3 e r a.p.k ç.0.s 6 where N = number of effective turns, k = transverse edge effecfc factor.m - number of phases, p = resistivitg 2p = number of poles, Ç = pole pich, A = 4.59 a constant and 0= phase angle of rotor impedance. The fcorques produced bH the deep squirrel cage and solid-rotor are calculated seperately and presented in Fiğ. 6. in order to evaluate the success of the theoretical studg. The experimental results are presented on the same figüre. The experimental and theoretical values are in good agreement. it is seen that the model vhich takes the deep squirrel cage in solid rotor machine is successf ull_r enables to calculate the perfomance values. 1.5 l l l I j j 1 } j 1 *" '*"."!»._ - i KT^^IIZIZIIIZI t heo ret i c al ^... ____^ ______ '"'.'.""-.. experimental ""'.Ss" '' r**. "X ol-M l l l Iztıoz: 0 N l600 i Figüre 6. The theoretical and experimental torque-speed of the solid-rotor deep-cage values induction motor. xi performance values are recorded. In order to calculate the theoretical performance of the drive system, a mathematical model for the motor is developed. This mathematical model does not onla take the solid-rotor structure but also takes the deep-cage which is embedded in the rotor. It is known that the generalised machine theory gives the penetration depth in steel as 5, 0 2B L in this equation ; 0 = flux per pole, B = 1. 8T saturation level for steel, L = length of the rotor. In order to take the deep cage effect, a dependent source is inserted in the rotor network of the equivalent circuit. When induction machine is starting, the rotor current frequency is 50 Hz therefore flux could not penetrate down to the cage and machine acts as solid rotor machine. However, when speed gets up, the rotor current frequency becomes lower and penetration depth becomes higher, and additional flux linkages the deep cage. For high speeds, rotor current flows in the cage and produces additional torques. A better torque-speed curves are obtained in high speed low slip region. The equivalent circuit of the induction motor which has deep rotor cage is given in Fig.S. Figure 5. The equivalent circuit of a solid rotor induction motor with deep rotor cage. The rotor impedance is given as, Z, A. m. p. L2N2B J0 Z = 3 e r a.p.k ç.0.s 6 where N = number of effective turns, k = transverse edge effecfc factor.m - number of phases, p = resistivitg 2p = number of poles, Ç = pole pich, A = 4.59 a constant and 0= phase angle of rotor impedance. The fcorques produced bH the deep squirrel cage and solid-rotor are calculated seperately and presented in Fiğ. 6. in order to evaluate the success of the theoretical studg. The experimental results are presented on the same figüre. The experimental and theoretical values are in good agreement. it is seen that the model vhich takes the deep squirrel cage in solid rotor machine is successf ull_r enables to calculate the perfomance values. 1.5 l l l I j j 1 } j 1 *" '*"."!»._ - i KT^^IIZIZIIIZI t heo ret i c al ^... ____^ ______ '"'.'.""-.. experimental ""'.Ss" '' r**. "X ol-M l l l Iztıoz: 0 N l600 i Figüre 6. The theoretical and experimental torque-speed of the solid-rotor deep-cage values induction motor.