本論文旨在於建立一以數位訊號處理器(Digital signal processor, DSP)為主之開關磁阻馬達(switched reluctance motor, SRM)驅動系統，並從事其切換及速度控制性能改善研究。首先探究馬達驅動系統組成及DSP數位控制實務，然後據以設計組立一以DSP為主之實驗用SRM驅動系統。接著在有關噪音及振動消除之研究方面，先探究其產生之來源、效應及暨有減輕噪音及振動之方法。然後研究及應用五種控制策略於所建構之馬達驅動系統上，並比較評估其效果和限制。這些策略含隨機頻率脈寬調變、導通及截止角度同步前移、截止角之隨機化改變，電流下降波形控制、及電流下降波形結合換相位置前移。最後一種為最有效之控制策略，可在噪音及振動消除與能量轉換效率綜合考量上得到最佳效能。
最後在速度控制方面，先在所選定之工作點從事所組馬達驅動系統之動態模式估測。再根據所給定的速度控制規格設計一雙自由度控制器及一線性模式追蹤控制器，使馬達驅動系統在系統參數或工作點變動下仍具有所欲之速度控制特性。為了進一步增加速度控制性能之強健性，設計了一個可變結構系統控制機構以決定模式追蹤控制器中之誤差增益值。模擬及實測結果顯示所提之具可變結構系統調適之模式追蹤速度控制機構具有良好之控制性能。

In this thesis, a digital signal processor (DSP)-based switched reluctance motor (SRM) drive is established, and its switching and speed control performance improvements are studied. First, the fundamentals about SRM drive and DSP-based control issues are understood. And accordingly an experimental DSP-based motor drive is designed and implemented. Second, in the studies concerning the reduction of acoustic noise and vibration, their sources, effects and existing mitigation approaches are first surveyed. Then five approaches are studied and applied to the established SRM drive to comparatively evaluate their effectiveness and limitations. These approaches include random frequency pulse width modulation (RFPWM), advanced turn-on and turn-off angles with fixed dwell angle, randomizing turn-off angle, current tail profiling, current tail profiling with advanced shift. The last approach is the most effective means to yield the compromised performance in acoustic noise and vibration reductions and energy conversion efficiency.
Finally, in the speed control aspect, a nominal dynamic model of the established SRM drive is first estimated. Then a two-degrees-of-freedom controller (2DOFC) and a linear model following controller (LMFC) are designed to let the motor driver possess prescribed speed control performance under varying system parameters and operating conditions. For further enhance the robustness of speed control performance, a VSS controller is designed to determine the feedback error gain in the model following control scheme. The effectiveness of the proposed VSS-adapted model following speed control scheme is verified by some simulated and experimental results.

A. Fundamentals of SRM
[1] T. J. E. Miller, Brushless Permanent-Magnet and Reluctance Motors Drives, Clarendon Press, Oxford, 1989.
[2] T. J. E. Miller, Switched Reluctance Motors and Their Control, Clarendon Press, Oxford, 1993.
[3] P. C. Sen, Principles of Electrical Machines and Power Electronics, John Wiley & Sons, 1997.
[4] J. J. Cathey, Electric Machines: Analysis and Design Applying Matlab, McGraw Hill, 2001.
[5] R. Krishnan, Switched Reluctance Motor Drives: Analysis, Design and Application , CRC Press, New York, 2001.
[6] K. I. Hwu, “Development of a switched reluctance motor drive,” Ph.D. Dissertation, Deparment of Electrical Engineering, National Tsing Hua University, ROC, 2001.
[7] Y. Hayashi and T. J. E. Miller, “A new approach to calculating core losses in the SRM,” IEEE Trans. on Industrial Application, vol. 31, no. 3, pp. 1039-1046, 1995.
[8] M. E. Hall, S. S. Ramamurthy and J. C. Balda, “An enhanced simple method for designing switched reluctance motors under multi-phase excitation,” Electric Machines and Drives Conference, pp. 715-720, 2001.
[9] T. J. E. Miller, “Optimal design of switched reluctance motors,” IEEE Trans. on Industrial Electronics, vol. 49, no. 1, pp. 15-27, 2002.
[10] B. Mirzaeian, M. Moallem, V. Tahani and C. Lucas, “Multiobjective optimization method based on a genetic algorithm for switched reluctance motor design,” IEEE Trans. on Magnetics, vol. 38, no. 3, pp. 1524-1527, 2002.
[11] W. Wu, J. B. Dunlop, S. J. Collocott and B. A. Kalan, “Design optimization of a switched reluctance motor by electromagnetic and thermal finite-element analysis,” IEEE Trans. on Magnetics, vol. 39, no. 5, pp. 3334-3336, 2003.
B. Converters and voltage boosting control
[12] P. K. Sood, Power converter for a switched reluctance motor, U.S. Patent 5225 181, 1992.
[13] M. Ehsani, J. T. Bass, T. J. E. Miller and R. L. Steigerwald, “Development of a unipolar converter for switched reluctance motor drive,” IEEE Trans. on Industrial Application, vol. 23, no. 3, pp. 545-553, 1987.
[14] C. Pollock and B. W. Williams, “A unipolar converter for a switched reluctance motor,” IEEE Trans. on Industrial Application, vol. 26, no. 2, pp. 222-228, 1990.
[15] S. Vukosavic and V. R. Stefanovic, “SRM inverter topologies: a comparative evaluation,” IEEE Trans. on Industrial Application, vol. 27, no. 6, pp. 1034-1049, 1991.
[16] C. Pollock and M. Barnes, “Power electronic converters for switched reluctance drives,” IEEE Trans. on Power Electronics, vol. 13, no. 6, pp. 1100-1111, 1998.
[17] Y. G. Dessouky, B. W. Williams and J. E. Fletcher, “A novel power converter with voltage-boosting capacitors for a four-phase SRM drive,” IEEE Trans. on Industrial Application, vol. 45, no. 5, pp. 815-823, 1998.
[18] K. I. Hwu and C. M. Liaw, “DC-link voltage boosting and switching control for switched reluctance motor drives,” IEE Proc. Electric Power Applications, vol. 147, no. 5, pp. 337-344, 2000.
[19] M. Dahmane, F. M. Tabar and F. M. Sargos, “An adapted converter for switched reluctance motor/generator for high speed applications,” Industry Applications Conference, Conference Record of the 2000 IEEE, vol. 3, pp. 1547-1554, 2000.
[20] C. Hao and Z. Dong, “Analysis of the two types of the four-phase switched reluctance motor drive” ICEMS 2001, vol. 2, pp. 982-985, 2001.
[21] S. J. Watkins, J. Corda and L. Zhang, “Multilevel asymmetric power converters for switched reluctance machines,” International Conference on Power Electronics, Machines and Drives, pp. 195-200, 2002.
[22] K. Y. Cho, “Power converter circuit for a switched reluctance motor using a flyback transformer,” IEE Proc. Electric Power Applications, vol. 150, no. 1, pp. 88-96, 2003.
C. Soft switching
[23] G. Hua, C. Leu, Y. Jiang and F. C. Lee, “Novel zero-voltage-transition PWM converter,” IEEE Trans. on Power Electronics, vol. 9, no. 1, pp. 213-219, 1994.
[24] G. Hua, E. X. Yang, Y. Jiang and F. C. Lee, “Novel zero-current-transition PWM converters,” IEEE Trans. on Power Electronics, vol. 9, no. 6, pp. 601-606, 1994.
[25] K. T. Chau, T. W. Ching, C. C. Chan and M. S. W. Chan, “A novel zero-current soft-switching converter for switched reluctance motor drives,” IEEE Proc., IECON'98, vol. 2, pp. 893-898, 1998.
[26] Y. Murai, J. Cheng and M. Yoshida, “New soft-switched reluctance motor drive circuit,” IEEE Industrial Application Conference, vol. 1, pp. 676-681, 1997.
[27] K. M. J. Smith and K. M. Smedley, “A comparison of voltage-mode soft-switching methods for PWM converters,” IEEE Trans. on Power Electronics, vol. 12, no. 2, pp. 376-386, 1997.
[28] Y. Murai, J. Cheng and M. Yoshida, “A soft-switched reluctance motor drive circuit with improved performances,” Power Electronic Specialists Conference, PESC '97 Record, 28th Annual IEEE, vol. 2, pp. 881-886, 1997.
[29] Y. Murai and J. Cheng, “A simple soft-switched switched-reluctance motor drive,” IEEE Proc. IECON '98, vol. 2, pp. 911-916, 1998.
[30] T. W. Ching, K. T. Chau and C. C. Chan, “A new zero-voltage-transition converter for switched reluctance motor drives,” Power Electronics Specialists Conference, PESC 98 Record, vol. 2, pp. 1295-1301, 1998.
[31] J. Cheng, M. Yoshida and Y. Murai, “Analysis and application of a part resonant circuit for switched reluctance motor,” IEEE Proc. IECON'99, vol. 3, no. 2, pp. 1115-1120, 1999.
[32] Y. Murai, J. Cheng and M. Yoshida, “New soft-switched/switched-reluctance motor drive circuit,” IEEE Trans. on Industrial Application, vol. 35, no. 1, pp. 78-85, 1999.
[33] L. G. B. Rolim, W. I. Suemitsu, E. H. Watanabe and R. Hanitsch, “Development of an improved switched reluctance motor drive using a soft-switching converter,” IEE Electric Power Application, vol. 146, no. 5, pp. 488-494, 1999.
[34] Y. Murai, J. Cheng, S. Sugimoto and M. Yoshida, “A capacitor-boosted, soft-switched switched-reluctance motor drive,” Applied Power Electronic Conference APEC'99, vol. 1, pp. 424-429, 1999.
[35] L. P. B. Oliveira, E. R. Silva, A. M. N. Lima and C. B. Jacobina, “New soft-switched power converter topologies for variable reluctance machine drives,” IEEE Proc. PESC’99, vol. 2, pp. 826-831, 1999.
[36] Y. berkovich and A. Ioinovici, “High efficient PWM zero-voltage-transition boost converter: AC small signal analysis,” IEEE Trans. on Circuits System I, vol. 47, no. 6, pp. 860-867, 2000.
[37] H. J. Chen, “Design and implementation of a soft-switching converter-fed switched reluctance motor drive,” Master Thesis, Department of Electrical Engineering, National Tsing Hua University, ROC, 2002.
[38] Y. Zhang and P. C. Sen, “A new soft-switching technique for buck, boost, and buck-boost converters,” IEEE Trans. on Industry Applications, vol. 39, no. 6, pp. 1775-1782, 2003.
[39] N. Jain, P. K. Jain and G. Joos, “A zero voltage transition boost converter employing a soft switching auxiliary circuit with reduced conduction losses,” IEEE Trans. on Power Electronics, vol. 19, no. 1, pp. 130-139, 2004.
[40] H. Bodur and A. F. Bakan, “An improved ZCT-PWM DC–DC converter for high-power and frequency applications,” IEEE Trans. on Industrial Electronics, vol. 51, no. 1, pp. 89-95, 2004.
D. Commutation control and torque ripple reduction
[41] H. Cailleux, B. L. Pioufle, B. Multon and C. Sol, “A precise analysis of the phase commutation for the torque nonlinear control of a switched reluctance motor - torque ripples minimization,” IEEE Proc. Industrial Electronics, Control, and Instrumentation, vol. 3, pp. 1985-1990, 1993.
[42] D. S. Reay, T .C. Green and B. W. Williams, “Neural networks used for torque ripple minimisation from a switched reluctance motor,” Conference on Electronics and Applications, vol. 6, pp. 1-6, 1993.
[43] I. Husain and M. Ehsani, “Torque ripple minimization in switched reluctance motor drives by PWM current control,” IEEE Trans. on Power Electronics, vol. 11, no. 1, pp. 83-88, 1996.
[44] K. Russa, I. Husain and M. E. Elbuluk, “Torque-ripple minimization in switched reluctance machines over a wide speed range,” IEEE Trans. on Industry Applications, vol. 34, no. 5, pp. 1105-1112, 1998.
[45] M. S. Islam and J. Husain, “Torque-ripple minimization with indirect position and speed sensing for switched reluctance motors,” IEEE Trans. on Industry Electronics, vol. 47, no. 5, pp. 1126-1133, 2000.
[46] Z. Z. Ye, T. W. Martin and J. C. Balda, “Control of a 10/8 SRM based on the torque ripple minimization and speed feedback,” Power Electronics Specialists Conference, vol. 3, pp. 1695-1700, 2001.
[47] I. Husain, “Minimization of torque ripple in SRM drives,” IEEE Trans. on Industrial Electronics, vol. 49, no. 1, pp. 28-39, 2002.
[48] K. I. Hwu and C. M. Liaw, “Intelligent tuning of commutation for maximum torque capability of a switched reluctance motor,” IEEE Trans. on Energy Conversion, vol. 18, no. 1, pp. 113-120, 2003.
E. Acoustic noise reduction
[49] D. E. Cameron, J. H. Lang and S. D. Umans, “The origin and reduction of acoustic noise in doubly salient variable-reluctance motors,” IEEE Trans. on Industry Applications, vol. 28, no. 1, pp. 1250-1255, 1992.
[50] C. Y. Wu and C. Pollock, “Analysis and reduction of vibration and acoustic noise in the switched reluctance drive,” IEEE Trans. on Industry Applications, vol. 31, no. 2, pp. 91-98, 1995.
[51] A. Michaelides and C. Pollock, “Reduction of noise and vibration in switched reluctance motors: new aspects,” Industry Applications Conference, vol. 2, pp. 771-778, 1996.
[52] R. S. Colby, F. M. Mottier and T. J. E. Miller, “Vibration modes and acoustic noise in a four-phase switched reluctance motor,” IEEE Trans. on Industry Applications, vol. 32, no. 2, pp. 1357-1364, 1996.
[53] C. Pollock and C. Y. Wu, “Acoustic noise cancellation techniques for switched reluctance drives,” IEEE Trans. on Industry Applications, vol. 33, no. 1, pp. 477-484, 1997.
[54] K. B. Kim, “Field analysis of low acoustic noise switched reluctance motor,” IEEE Trans. on Magnetics, vol. 33, no. 1, pp. 2026-2029, 1997.
[55] M. Gabsi, F. Camus, T. Loyau and J. L. Barbry, “Noise reduction of switched reluctance machine,” Proc. IEMD Conference, pp. 263-265, 1999.
[56] B. Fahimi and M. Ehsani, “Spatial distribution of acoustic noise caused by radial vibration in switched reluctance motors: application to design and control,” Industry Applications Conference, Conference Record of the 2000, vol. 1, pp. 114-118, 2000.
[57] W. Cai, P. Pillay and A. Onekanda, “Analytical formulae for calculating SRM modal frequencies for reduced vibration and acoustic noise design,” Electric Machines and Drives Conference, vol. 2, pp. 203-207, 2001.
[58] W. Cai, P. Pillay, Z. Tang and A. Omekanda, “Experimental study of vibrations in the switched reluctance motor,” Electric Machines and Drives Conference, vol. 1, pp. 576-581, 2001.
[59] J. W. Moon, J. Kim, S. G. Oh and J. W. Ahn, “Reduction of vibration and acoustic noise of SRM with hybrid excitation method,” IEEE Proc. Industrial Electronics, vol. 2, no. 1, pp. 1407-1412, 2001.
[60] J. O. Fiedler and R. W. D. Doncker, “ Extended analytic approach to acoustic noise in switched reluctance drives,” Power Electronics Specialists Conference, vol. 4, pp. 1960-1964, 2002.
[61] M. Takemoto, A. Chiba, H. Akagi and T. Fukao, “ Radial force and torque of a bearingless switched reluctance motor operating in a region of magnetic saturation,” Industry Applications Conference, Conference Record of the 2002, vol. 1, pp. 35-42, 2002.
[62] F. Blaabjerg and J. K. Pedersen, “ Digital implemented random modulation strategies for AC and switched reluctance drives,” IEEE Proc. IECON'93, vol. 2, no. 3, pp. 676-682, 1993.
[63] T. Boukhobza, M. Gabsi and B. Grioni, “Random variation of control angles, reduction of SRM vibrations,” Electric Machines and Drives Conference, IEMDC 2001, vol. 3, pp. 640-643, 2001.
[64] B. Fahimi, G. Suresh, K. M. Rahman and M. Ehsani, “Mitigation of acoustic noise and vibration in switched reluctance motor drive using neural network based current profiling,” Industry Applications Conference, vol. 1, pp. 715-722, 1998.
[65] J. W. Ahn, S. J. Park and D. H. Lee, “Hybrid excitation of SRM for reduction of vibration and acoustic noise,” IEEE Trans. on Industrial Electronics, vol. 51, no. 2, pp. 374-380, 2004.
[66] K. H. Ha, Y. K. Kim, G. H. Lee and J. P. Hong, “Vibration reduction of switched reluctance motor by experimental transfer function and response surface methodology,” IEEE Trans. on Industrial Electronics, vol. 40, no. 2, pp. 577-580, 2004.
F. Current control
[67] J. M. D. Murphy and F. G. Turnbull, Power Electronic Control of AC Motors, Pergamon Press, Oxford, 1989.
[68] B. K. Bose, “An adaptive hysteresis-band current control technique of a voltage-fed PWM inverter for machine drive system,” IEEE Trans. on Industrial Electronics, vol. 37, no. 5, pp. 402-408, 1990.
[69] H. L. Huy, K. Slimani and P. Viarouge, “A current-controlled quasi-resonant converter for switched-reluctance motor,” IEEE Trans. on Industrial Electronics, vol. 38, no. 5, pp. 355-362, 1991.
[70] J. Holtz, “Pulsewidth modulation-a survey,” IEEE Trans. on Industrial Electronics, vol. 39, no. 5, pp. 410-420, 1992.
[71] F. Briz, A. Diez, M. W. Dengner and R. D. Lorenz, “Current and flux regulation in field-weakening operation of induction motors,” IEEE Trans. on Industrial applications, vol. 37, no. 1, pp. 42-50, 2001.
[72] M. P. Kazmierkowski and L. Malesani, “Current control techniques for three-phase voltage-source PWM converters: a survey,” IEEE Trans. on Industrial Electronics, vol. 45, no. 5, pp. 691-703, 1998.
[73] F. Blaabjerg, P. C. Kjaer, P. O. Rasmussen and C. Cossar, “Improved digital current control methods in switched reluctance motor drives,” IEEE Trans. on Industrial Electronics, vol. 14, no. 3, pp. 563-572, 1999.
[74] M. T. Alrifai, J. H. Chow and D. A. Torrey, “Practical application of backstepping nonlinear current control to a switched-reluctance motor,” American Control Conference, vol. 1, pp. 594-599, 2000.
[75] P. L. Chapman and S. D. Sudhoff, “Optimized waveform control for an 8/6 switched reluctance motor drive,” Applied Power Electronics Conference and Exposition, vol. 2, pp. 1096-1102, 2001.
[76] G. G. Lopez and K. Rajashekara, “Peak PWM current control of switched reluctance and AC machines,” Industry Applications Conference, vol. 2, pp. 1212-1218, 2002.
G. Speed control
[77] T. S. Chuang and C. Pollock, “Robust speed control of a switched reluctance vector drive using variable structure approach,” IEEE Trans. on Industrial Electronics, vol. 44, no. 1, pp. 800-808, 1997.
[78] K. I. Hwu and C. M. Liaw, “Quantitative speed control for SRM drive using fuzzy adapted inverse model,” IEEE Trans. on Electronics System, vol. 38, pp. 955-968, 2002.
[79] V. K. Sharma, B. Singh, S. S. Murthy, A. Chandra and K. A. Haddad, “Performance analysis of fuzzy logic based speed controller for switched reluctance motor drive,” Power electronics, Drives and Energy System for Industrial Growth, Proceedings of the 1996 International Conference on, vol. 1, pp. 8-11, 1996.
[80] C. Visa, G. Abba and F. Leonard, “Speed control of a switched reluctance motor using non-linear methods,” Conference on Systems, Man and Cybernetics, vol. 5, pp. 1-6, 2002.
[81] C. M. Liaw, “Design of a two-degree-of-freedom controller for motor drives,” IEEE Trans. on Automatic Control, vol. 37, no. 8, pp. 1215-1220, 1992.
[82] F. J. Lin and C. M. Liaw, “Reference model selection and adaptive control for induction motor drives,” IEEE Trans. Automat. Contr., vol.38, no. 10, pp. 1594-1600, 1993.
[83] T. G. Lee and U. Y. Huh, “An error feedback model based adaptive controller for nonlinear systems,” IEEE Proc. Industrial Electronics, vol. 3, no. 4, pp. 1095-1100, 1997.
[84] A. D. Cheok and N. Ertugrul, “Use of fuzzy logic for modeling, estimation, and prediction in switched reluctance motor drives,” IEEE Trans. on Electronics System, vol. 46, no. 6, pp. 1207-1224, 1999.
[85] C. Lucas, M. M. Shanehchi, P. Asadi and P. M. Rad, “A robust speed controller for switched reluctance motor with nonlinear QFT design approach,” Industry Applications Conference, vol. 3, pp. 1573-1577, 2000.
[86] B. Fahimi, “Design of adjustable speed switched reluctance motor drives,” Industrial Electronics Society, vol. 3, no. 2, pp. 1577-1582, 2001.
[87] J. Seo, H. R. Cha, H. Yang, J. C. Seo and K. H. Kim, Y. C. Lim and D. H. Jang, “Speed control method for switched reluctance motor drive using self-tuning of switching angle,” IEEE Proc. Industrial Electronics, vol. 2, no. 1, pp. 811-815, 2001.
[88] G. Wei, M. Zhiyuan and Z. Qionghua, “An simplified estimation method of PI control parameters for switched SRM drive system,” Conference on Electrical Machines and System, vol. 2, pp. 946-949, 2001.
[89] J. Y. Seo, H. R. Cha, H. Y. Yang, J. C. Seo, K. H. Kim, Y. C. Lim and D. H. Jang, “Speed control method for switched reluctance motor drive using self-tuning of switching angle,” Industrial Electronics, 2001. Proceedings. ISIE 2001. IEEE International Symposium on, vol. 2, pp. 811-815, 2001.
[90] K. I. Hwu and C. M. Liaw, “Robust quantitative speed control of a switched reluctance motor,” IEE Proc. Electric Power Applications, vol. 148, no. 4, pp. 345-353,2001.
[91] A. S. B. F. Rahman and M. N. B. Taib, “Simulation of PID and fuzzy logic controller for the newly developed switched reluctance motor program,” Conference on Research and Development, vol. 4, pp. 49-53, 2002.
[92] Z. Z. Ye, T. W. Martin, J. C. Balda and R. M. Schupbach, “Feedback control of an 8/6 SRM under multiphase excitation mode with short flux paths,” IECON 02, vol. 2, pp. 1072-1078, 2002.
[93] M. T. Alrifai, J. H. Chow and D. A. Torrey, “Backstepping nonlinear speed controller for switched-reluctance motors,” IEE Proc. Electric Power Application, vol. 150, no. 2, pp. 193-200, 2003.
[94] O. Barambones, A. J. Garrido and F. J. Maseda, “A robust field oriented control of induction motor with flux observer and speed adaptation,” IEE Proc. Emerging Technologies and Factory Automation,, vol. 1, no. 2, pp. 245-252, 2003.
[95] K. T. Chau, S. W. Chung and C. C. Chan, “Neuro-fuzzy speed tracking control of traveling-wave ultrasonic motor drives using direct pulsewidth modulation,” IEEE Trans. on Electronics System, vol. 39, no. 4, pp. 1061-1069, 2003.
H. Digital signal processing
[96] F. Nekoogar and G. Moriarty, Digital Control Using Digital Signal Processing, Prentice Hall PTR, New Jersey, 1999.
[97] J. G. Bollinger and N. A. Duffie, Computer Control of Machines and Processes, Addison-Wesley, Massachusetts, 1988.
[98] G. F. Franklin, J. D. Powell and M. L. Workman, Digital Control of Dynamic Systems, 2nd Edition, Addison Wesley, New York, 1990.
[99] D. Krakauer, Single Chip DSP Motor Control Systems Catching on in Home Appliances, Analog Devices Inc., USA, 2000.
[100] S. Y. R. Hui, I. Oppermann and S. Sathiakumar, “Microprocessor-based random PWM schemes for DC-AC power conversion,” IEEE Trans. on Power Electronics, vol. 12, no. 2, pp.253-260, 1997.
I. Random switching
[101] T. Tanaka, T. Ninomiya and K. Harada, “Random-switching control in DC-to-DC converters,” Power Electronics Specialists Conference, PESC '89 Record, Vol. 1, pp. 500-507, 1989.
[102] A. M. Trzynadlowski, F. Blaabjerg, J. K. Pedersen, R. L. Kirlin and S. Legowski, “Random pulse width modulation techniques for converter fed drive systems-a review,” Industry Applications Society Annual Meeting, Conference Record of the 1993, vol. 2, pp. 136-1143, 1993.
[103] G. A. Covic and J. T. Boys, “Noise quieting with random PWM AC drives,” IEE Proc. Electric Power Applications, vol. 145, no. 1, pp. 1-10, 1998.
[104] K. K. Tse, H. S. H. Chung, S. Y. R. Hui and H. C. So, “A comparative study of using random switching schemes for DC/DC converters,” APEC '99, vol. 1, pp. 893-898, 1999.
[105] C. M. Liaw and Y. M. Lin, “Random slope PWM inverter using existing system background noise: Analysis, design and implementation,” IEE Proc. Electric Power Applications, vol. 147, no. 1, pp. 45-54, 2000.
[106] R. L. Kirlin, M. M. Bech and A. M. Trzynadlowski, “Analysis of power and power spectral density in PWM inverters with randomized switching frequency,” IEEE Trans. on Industrial Electronics, vol. 49, no. 2, pp. 486-499, 2002.