Plans of Future Research Work
In Chapter 1 the effect of the sampling techniques of three widely applied carrier based Pulse Width Modulation (PWM) techniques were investigated. In recent years, the development of the chaotic Pulse Width Modulation (PWM) techniques have received considerable attention and a number of ideas to generate random-like chaotic PWM signals have been tested in dif-ferent systems [53]. In most cases the logistic map is applied to chaoize a frequency-modulated signal. Then it modulates the carrier frequency of the standrad PWM techniques, like Sinu-soidal PWM or Space Vector Modulation [92]. One of the main advantages of the chaotic PWM techniques is that it can improve the Electromagnetic Compatibility of the converters applying high switching frequencies. Furthermore, it can also suppress the acoustic noise in PWM drive systems [53]. In the future I would like to implement chaotic carrier based PWM techniques applying other map functions than the Logistic map and investigate their effect on the operation of high speed drives.
In Chapter 2 a novel stability analysis method using the auxiliary state vector was suc-cessfully applied for DC servo motor and for a single phase Power Factor Correction (PFC) power electronic converter. Furthermore, the chaotic and oscillating response are stabilized by adding a stabilizing signal in the control loop. The parameters of the stabilizing signal were calculated by the auxiliary state vector as well. In the future I would like to apply the stability analysis for three phase motor drives, like Brushless DC motor or hystersis controlled induction machine, and for three phase converters, like three phase PFC converters, as well. By applying different stabilizing signal I would like to extend the stabiltiy range of the investigated systems.
Single phase quadratic converter topology, where the voltage ratio is given as a quadratic function of the duty ratio, has many advantages [93], like greater voltage ratio in comparison with the basic configurations and better efficiency. Later I would like to investigate a single phase quadratic converter and design its controller parameters applying again the auxiliary state vector.
In Chapter 3 a speed sensor-less Field Oriented Controlled induction machine drive was investigated by comparing two SVM sampling techniques: Regular Sampling (RS) and Dou-blesampling (DS). Natural Sampling is often referred to as the best form of sampling technique in closed loop applications [34] when the sampling to fundamental frequency F is low, as it does not introduce delay. As it was presented in Chapter 1 I developed and successfully im-plemented a method in a digital microcontroller for realizing SVM applying Natural Sampling with high precision in open-loop. In the future I would like to extend the method to closed loop operation as well and compare its performance with the RS and DS sampling techniques for low mf that is for high speed drives. Due to its parallel computation properties, FPGA has many advantage over microcontrollers. Later I would like to implement the closed loop algorithm applying NS SVM in an FPGA as well.
In the dissertation the carrier frequency fc is set to be constant resulting in variable non integer frequency ratio mf =fc/f1 as f1 is varied by the controller resulting in asynchronous PWM. In the future I would like to implement synchronous PWM technique and keepingmf constant by varying fc as well.
Author’s publications
[A1] P. Stumpf, R. K. J´ard´an, and I. Nagy, “Analysis of the impact of space vector modu-lation techniques on the operation of ultrahigh speed induction machines,”Mathematics and Computers in Simulation, Elsevier, vol. 90, pp. 132–144, 2013.
[A2] P. Stumpf, R. K. J´ard´an, and I. Nagy, “Subharmonics generated by space vector mod-ulation in ultrahigh speed drives,” IEEE Transactions on Industrial Electronics, vol. 59, no. 2, pp. 1029–1037, 2012.
[A3] R. K. J´ard´an,P. Stumpf, P. Bartal, Z. Varga, and I. Nagy, “A novel approach in studying the effects of subharmonics on ultrahigh-speed ac motor drives,” IEEE Transactions on Industrial Electronics, vol. 58, no. 4, pp. 1274–1281, 2011.
[A4] P. Stumpf, R. K. J´ard´an, and I. Nagy, “Comparison of naturally sampled pwm tech-niques in ultrahigh speed drives,” in 2012 IEEE International Symposium on Industrial Electronics (ISIE), Hangzhou, China, pp. 246–251, IEEE, 2012.
[A5] P. Stumpf, R. K. J´ard´an, and I. Nagy, “DC components and subharmonics generated by naturally sampled pwm techniques,” in IECON 2012-38th Annual Conference on IEEE Industrial Electronics Society, Montreal, Canada, pp. 327–332, IEEE, 2012.
[A6] P. Stumpf, Z. Varga, R. J. Kalman, and I. Nagy, “Analysis of space vector modula-tion techniques applied in voltage source converters of ultrahigh speed inducmodula-tion motor drives,” in Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011), Birmingham, UK, pp. 1–10, IEEE, 2011.
[A7] P. Stumpf, D. T. Sepsi, R. K. Jardan, and I. Nagy, “Space vector modulation techniques applied in voltage source converters of ultrahigh speed induction machines,” in2011 IEEE International Symposium on Industrial Electronics (ISIE), Gdansk, Poland, pp. 402–407, IEEE, 2011.
[A8] P. Stumpf, Z. Varga, T. Sepsi, R. K. J´ard´an, and I. Nagy, “Ultrahigh speed induction machine overheated by subharmonics of pwm inverter,” in IECON 2010-36th Annual Conference on IEEE Industrial Electronics Society, Glendale, USA, pp. 1754–1759, IEEE, 2010.
[A9] P. Stumpf and I. Nagy, “Motor drive stabilization in its chaotic region,” Transactions on Electrical Engineering, vol. 1, no. 1, pp. 19 – 25, 2012.
[A10] P. Stumpf, A. L˝orincz, and I. Nagy, “Stability of digitally controlled PFC boost con-verter with auxiliary state vector,” in2013 IEEE International Symposium on Industrial Electronics (ISIE), Taipei, Taiwan, pp. 1–6, IEEE, 2013.
[A11] P. Stumpf, A. L˝orincz, and I. Nagy, “Analysis and compensation of oscillations in digitally controlled pfc converter,” in IECON 2013-39th Annual Conference on IEEE Industrial Electronics Society, Wien, Austria, pp. 8348–8353, IEEE, 2013.
[A12] P. Stumpf, Z. S¨ut˝o, and I. Nagy, “Unexpected test results with variable structure nonlinear systems and their theoretical background,” inPEIA 2011 Workshop on Power Electronics in Industrial Applications and Renewable Energy, Doha, Qatar, pp. 39 – 44, IEEE, 2011.
[A13] P. Stumpf and I. Nagy, “ ´Alland´o m´agneses egyen´aram´u hajt´as kaotikus viselked´ese (in Hungarian),” inOG ´ET XIX. Nemzetk¨ozi G´ep´eszeti Tal´alkoz´o, Cs´ıksomly´o, Rom´ania, pp. 335 – 338, 2011.
[A14] P. Stumpf, A. Lorincz, and I. Nagy, “Analysis and compensation of chaotic response in DC motor drive,” in 3rd International Students Conference on Electrodynamics and Mechatronics, Opole, Poland, pp. 83 – 88, 2011.
[A15] P. Stumpf, R. J. Kalman, and I. Nagy, “Digitally implemented naturally sampled svm applied in speed sensor-less field oriented controlled induction motor drive,” inProceedings of the 12th Brazilian Power Electronics Conference (COBEP2013), Gramado, Brazil, pp. 793–800, SOBRAEP, 2013.
[A16] P. Stumpf, R. K. Jardan, and I. Nagy, “Effect of sampling space vector modulation in speed control loops of ultrahigh speed drives,” in2012 15th International Power Elec-tronics and Motion Control Conference (EPE/PEMC), Novi Sad, Serbia, pp. LS6a–3, IEEE, 2012.
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