太陽光伏能源(PV)是重要的再生能源之一，因為它是乾淨、無空氣和噪音污染並取之不盡，用之不竭的。在太陽能發電系統中，為了提高轉換效率，最大功率追蹤技術(MPPT)必須具有快速反應，並能夠在任何天氣條件下追蹤至最大功率點。針對此特點文獻裡有許多的MPPT技術都已提出相關方法並進一步實現。其中，擾動觀察法(P&O)是最常見的、簡單的，而且易於實現，且性能良好。P&O遭遇了控制擾動增量值的權衡，亦即較小的擾動值在穩態時可以減少功率損，而較大的擾動值能夠改善日照快速變化或是負載改變時的動態反應。
本論文提出了變動步階式擾動觀察法來處理控制擾動增量值所遇到的問題。升壓式轉換器作為功率級並使用瑞薩公司所出產的微處理器RX62T來實現最大功率追蹤法。變動步階式擾動觀察法實現所面臨的困難之一是如何正確地選擇比例因子(M)，錯誤的M值選擇很容易導致不穩定或無效率的追蹤。在本論文中，M值的選擇是在太陽能光伏系統的模擬基礎上做深入研究。模擬與實驗都驗證了變動步階式擾動觀察法的可行性。根據實驗結果，所提出的變動步階式擾動觀察法，相較於傳統的P&O的算法，確實可以實現穩態時有較高的效率與較快的追蹤速度。

Photovoltaic (PV) energy is one of the most important renewable energy sources since it is clean, free and inexhaustible. To improve the conversion efficiency, a maximum power point tracking (MPPT) technique which has quick response and is able to track the peak power generated in any weather condition is required. Many MPPT techniques have been proposed and implemented in the literatures. Among them, the perturbation and observation (P&O) method is the most common for simplicity, ease of implementation, and good performance. P&O algorithms suffer a tradeoff in choosing the increment value of the control variable; small values decrease the losses in steady state due to small perturbations around the maximum power point (MPP), while large values improve the dynamic behavior in situations involving quickly changing irradiation conditions or load.
In this thesis, a variable step-size P&O method is implemented to deal with this problem. A boost converter is used as the power stage and the MPPT controller is realized using microcontroller RX62T from RENESAS corp. One of the difficulties faced in the implementation of variable step size algorithms is in finding the right value of the scaling factor M. A poor choice of M can easily lead to instability or inefficient tracking. In this thesis, the value M is selected based on intensive study of the simulation of the PV system. Simulation and experiments are carried out to validate the feasibility of the presented algorithm. According to the experimental results, the presented variable step-size algorithm can achieve high static tracking efficiency and faster tracking speed comparing to conventional P&O algorithms.

[1] Fangrui Liu, Shanxu Duan, Fei Liu, Bangyin Liu, and Yong Kang, “A Variable Step Size INC MPPT Method for PV Systems,” Industrial Electronics, IEEE Transactions on Volume: 55 , Issue: 7, pp.2622-2628, 2008.
[2] Noppadol Khaehintung, Theerayod Wiangtong and Phaophak Sirisuk, “FPGA Implementation of MPPT Using Variable Step-Size P&O Algorithm for PV Applications,” Communications and Information Technologies, 2006. ISCIT '06. International Symposium, pp.212-215, 2006.
[3] Ahmed K. Abdelsalam, Ahmed M. Massound, Shehab Ahmed, and Prasad N. Enjeti, “High-Performance Adaptive Perturb and Observe MPPT Technique for Photovoltaic-Based Microgrids,” Industrial Electronics, IEEE Transactions on Vol.26 ,N0.7,April 2011, pp.1010-1021, 2011.
[4] Mao-Lin Chiang, Chih-Chiang Hua, Jong-Rong Lin “Direct Power Control for Distributed PV Power System,” Power Conversion Conference, 2002. PCC Osaka 2002, pp.311-315, 2002.
[5] Weidong Xiao, William G. Dunford, “A Modified Adaptive Hill Climbing MPPT Method for Photovoltaic Power Systems,” Power Electronics Specialists Conference, 2004. PESC 04. 2004 IEEE 35th Annual, Volume: 3, Page(s): 1957 - 1963 Vol.3, 2004.
[6] P.J Wolfs, L Iang, “A Single Cell Maximum Power Point Tracking Converter without a Current Sensor for High Performance Vehicle Solar Arrays,” Power Electronics Specialists Conference, 2005. PESC '05. IEEE 36th, Page(s): 165 - 171, 2005.
[7] Ashish Pandey, Nivedita Dasgupta and Ashok Kumar Mukerjee, “High-Performance Algorithms for Drift Avoidance and Fast Tracking in Solar MPPT System,” Energy Conversion, IEEE Transactions on Volume: 23 , Issue: 2, pp.681-689, June. 2008.
[8] Ahmad Al-Diab and Constantinos Sourkounis, “Variable step size P&O MPPT algorithm for PV systems,” Communications and Information Technologies, 2006. ISCIT '06. International Symposium, pp.212-215, 2006.
[9] Jiyong Li and Honghua. Wang, “A novel stand-alone PV generation system based on variable step size INC MPPT and SVPWM control,” Power Electronics and Motion Control Conference, 2009. IPEMC '09. IEEE 6th International, pp.2155-2160, 2009.
[10] Emad M. Ahmed, Masahito Shoyama, “Highly efficient variable-step-size maximum power point tracker for PV systems,” Electrical and Electronics Engineering (ISEEE), 2010 3rd International Symposium, pp.112-117, 2010.
[11] Emad M. Ahmed, Masahito Shoyama, “Single variable based variable step size maximum power point tracker for stand-alone battery storage PV systems,” Industrial Technology (ICIT), 2011 IEEE International Conference, pp.210-216, 2011.
[12] Chao Zhang, Dean Zhao, Jinjing Wang and Guichang Chen, “A modified MPPT method with variable perturbation step for photovoltaic system,” Power Electronics and Motion Control Conference, 2009. IPEMC '09. IEEE 6th International, pp.2096-2099, 2009.

[13] Chao Zhang and Dean Zhao, “A novel MPPT method with variable perturbation step for photovoltaic system,” Industrial Electronics and Applications, 2009. ICIEA 2009. 4th IEEE Conference, pp.2184-2187, 2009.
[14] Nicola Femia, Giovanni Petrone, Giovanni Spagnuolo and Massimo Vitelli, “Optimization of perturb and observe maximum power point tracking method,” Power Electronics, IEEE Transactions on Volume: 20, Issue: 4, pp.963-973, 2005.
[15] Chee Wei Tan, Tim C. Green and Carlos A. Hernandez-Aramburo, “Analysis of perturb and observe maximum power point tracking algorithm for photovoltaic applications,” Power and Energy Conference, 2008. PECon 2008. IEEE 2nd International, pp.237-242, 2008.
[16] Ahmed K. Abdelsalam, Ahmed M. Massoud, Shehab Ahmed and Prasad Enjeti, “High Performance Adaptive Perturb and Observe MPPT Technique for Photovoltaic Based Microgrids,” Power Electronics, IEEE Transactions on Volume: 26, Issue: 4, pp.1010-1021, 2011.
[17] Zhou Yan, Liu Fei, Yin Jinjun and Duan Shanxu, “Study on realizing MPPT by improved Incremental Conductance method with variable step-size,” Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference, pp.547-550, 2008.
[18] M. F. Ishengoma and E. L. Norum ,” Design and implementation of a digitally controlled stand-alone photovoltaic power supply,” Nordic Workshop on Power and Industrial Electronics, pp.12-14, 2002.
[19] N. Mutoh, M. Ohno, and T. Inoue, “A method for MPPT control while searching for Parameters corresponding to weather conditions PV Generation Systems,” IEEE Transactions on Industrial Electronics, vol. 53, issue: 4, pp.1055-1065, Aug. 2006.
[20] A.V. Jayawardena, W.M.D.T. Weerasinghe, W.S. Coorera, S.G. Abeyratne and K.R.M.N. Rathnayake, “Maximum power tracking for PVs with improved tracking accuracy at irradiance transients,” Sustainable Energy Technologies (ICSET), 2010 IEEE International Conference, pp.1-4, 2010.
[21] E. Koutroulis, K. Kalaitzakis, and N. C. Voulgaris, “Development of a Microcontroller-Based Photovoltaic Maximum Power Point Tracking Control System,” IEEE Transactions on Power Electronics, vol. 16, no. 1, pp. 46-54, Jan. 2001.
[22] K. H. Hussein, I. Muta, T. Hoshino, and M. Osakada, “Maximum Photovoltaic Power Tracking: an Algorithm For Rapidly Changing Atmospheric Condition,” Generation Transmission Distribution, vol. 142, no. 1, pp. 59-64, 1995.
[23] P. Midya, P. T. Kerin, R. J. Turnbull, R. Reppa and J. Kimball,” Dynamic Maximum Power Point Tracker for Photovoltaic Applications,” IEEE Transactions on Power Electronics, Vol. 2, pp, 1710-1716, 1996.
[24] R.W. Erickson and D. Maksmovic, Fundamentals of Power Electronics, 2nd Edition, 2000.
[25] Noppadol Khaehintung, Theerayod Wiangtong and Phaophak Sirisuk, “FPGA Implementation of MPPT Using Variable Step-Size P&O Algorithm for PV Applications,” Communications and Information Technologies, 2006. ISCIT '06. International Symposium, pp.212-215, 2006.
[26] 江炫樟，「電力電子學」第三版，全華圖書，民國九十四年八月。
[27] 梁適安，「交換式電源供給器之理論與實務設計」，全華圖書，民國九十三年十月。
[28] 王順忠，「電力電子學」，臺灣東華書局股份有限公司， 2001年。