本作品應用在手機適配器，符合最新USB PD 3.0規格，常用於作品規格之隔離型轉換器為返馳式轉換器，而傳統二次側回授控制返馳式轉換器需要隔離元件進行回授控制，本作品提出無隔離元件二次側回授返馳式轉換器，其搭配同步整流架構並利用同步整流電晶體達成零電壓軟切ZVS，以ZVS訊號將二次側輸出電壓資訊傳送給一次側，捨棄隔離元件降低成本，搭配變頻COT控制完成系統定電壓控制，在一次側ZVS訊號接收部分，使用輔繞電壓以及本作品提出之Zero Voltage Detector，無需任何高壓元件即可完成正確零電壓偵測。
本作品使用全數位控制，控制器硬體以FPGA實現搭配PCB功率級完成控制法驗證與作品量測，證實作品符合目標規格，在輸入110Vac下的Voltage Regulation±3%的成果並使用同步整流優化導通損耗及零電壓軟切優化切換損耗。

In this paper, the research topic is study and design of digitally controlled highefficiency secondary-side regulated flyback converter without galvanic isolation.
This work is applied to the mobile phone adapter with the latest USB PD 3.0 specification. Flyback is the most commonly used isolated converter in the specification, while the traditional secondary side regulated flyback converter requires isolation components for feedback control. This work proposes a secondary-side regulated flyback converter without any extra isolation components which can lower the cost and reduce the number of components. In addition, it achieves zero-voltage switching (ZVS) with synchronous rectification architecture and transfers the output voltage information from the secondary side to the primary side through the ZVS signal. The control scheme of the work is constant on time (COT) control to complete the constant voltage of the power converter. To receive the correct ZVS signal in primary side, the work senses the auxiliary winding voltage and proposes zero voltage detector in digital controller to avoid the need of complex circuit with high voltage components.
This work is digital controlled, and the controller hardware is realized by FPGA. As for the verification of the control method is completed by using the PCB board. The result of the measurement meets the target specification with voltage regulation of ±3% under 110Vac input.

[1] CUI. "Efficiency Standards for External Power Supplies" [Online]. Available: https://www.cui.com/catalog/resource/efficiency-standards-for-external-power-supplies.pdf
[2] Texas Instruments. "Keeping up with the standards: Efficiency and standby power requirements" [Online]. Available: https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/05/12/keeping-up-with-the-standards-efficiency-and-standby-power-requirements
[3] USB-IF. "USB Power Delivery Specification" [Online]. Available: http://www.usb.org/developers/powerdelivery/
[4] Texas Instruments. "Differences between PSR and SSR in bias power-supply design" [Online]. Available: http://e2e.ti.com/blogs_/b/powerhouse/archive/2016/04/08/differences-between-psr-and-ssr-in-bias-power-supply-design
[5] ON Semiconductor. DC-DC Converters Feedback and Control [Online]. Available: http://www.onsemi.cn/pub_link/Collateral/TND352-D.PDF
[6] Texas Instruments. "Differences between PSR and SSR in bias power-supply design" [Online]. Available: http://e2e.ti.com/blogs_/b/powerhouse/archive/2016/04/08/differences-between-psr-and-ssr-in-bias-power-supply-design
[7] Texas Instruments. “Zero-Voltage-Switching Flyback Using UCC28780 Controller and UCC5304 Isolated Synchronous-Rectifier Driver” [Online]. Available: https://www.ti.com/lit/an/sluaa60/sluaa60.pdf
[8] TexasInstruments. "Exposing the Inner Behavior of a Quasi-Resonant Flyback Converter" [Online]. Available: www.ti.com/lit/slup302
[9] Texas Instruments. " Control and Design Challenges for Synchronous Rectifier" [Online]. Available: https://www.ti.com/seclit/ml/slup378/slup378.pdf
[10] S. Maniktala, "Chapter 10 - Off-line Converter Design and Magnetics A2 - Brown, Marty," in Power Sources and SuppliesBurlington: Newnes, 2008, pp. 295-343.
[11] Infineon. Design Guide for Off-line Fixed Frequency DCM Flyback Converter [Online]. Available: https://www.mouser.com/pdfdocs/2-8.pdf
[12] Richtek. "Feedback Control Design of Off-line Flyback Converter" [Online]. Available: www.richtek.com/m/~/media/AN%20PDF/AN017_EN.pdf
[13] Texas Instruments. "Under the Hood of Flyback SMPS Designs " [Online]. Available: https://www.ti.com/seclit/ml/slup261/slup261.pdf
[14] S. Howimanporn and C. Bunlaksananusorn, "Performance comparison of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) flyback converters," The Fifth International Conference on Power Electronics and Drive Systems, 2003
[15] TexasInstruments. UCC28610. "Green-Mode Flyback Controller" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc28610.pdf
[16] TexasInstruments. UCC28600. "Quasi-Resonant Flyback Green-Mode Controller" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc28600.pdf
[17] Sanket Dessai, K. Ramakrishna, "Implementation of Video Capture and Playback in Mobile Systems, "International Journal of Reconfigurable and Embedded Systems (IJRES), November 2013
[18] Texas Instruments. UCC28722. "Constant-Voltage, Constant-Current Controller With Primary-Side Regulation, BJT Drive" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc28722.pdf
[19] Texas Instruments. "Safety Considerations in Power Supply Design" [Online]. Available: http://www.ti.com/lit/ml/slup224/slup224.pdf
[20] Dr. John Schönberger, "Design of a TL431-Based Controller for a Flyback Converter " [Online]. Available: https://www.plexim.com/files/plecs_tl431.pdf
[21] 陳達進, "高效率低成本數位控制適配器之研究與設計". 國立成功大學碩士論文, 2017年7月.
[22] Linear, "Switching regulator circuit using magnetic flux-sensing," Patent US5305192 A, 1991.
[23] Anthony T. Huynh, "Isolation techniques without an isolator" APEC 2018 [Online]. Available: https://www.psma.com/sites/default/files/uploads/tech-forums-safety-compliance/presentations/is094-isolation-techniques-without-isolator.pdf
[24] Power Intergrations, InnoSwitch3-CE [Online]. Available: https://www.power.com/sites/default/files/documents/innoswitch3-ce_family_datasheet_TW.pdf
[25] Analog Devices.ADuM246XA"Quad-Channel Isolators with Integrated DC-to-DC Converter" [Online]. Available: https://www.mouser.tw/datasheet/2/609/adum6420a_6421a_6422a_6423a_6424a-2401156.pdf
[26] Texas Instruments. "Keep Noise Out of Your System and Eliminate Ground Loops: How to Choose the Right Isolator" [Online]. Available: https://www.ti.com/lit/ml/sllp108/sllp108.pdf?ts=1660207619930&ref_url=https%253A%252F%252Fwww.google.com%252F
[27] Texas Instruments. UCC28781. " Zero-Voltage-Switching Flyback Controller with Dedicated Synchronous Rectifier Gate-Drive" [Online]. Available: https://www.ti.com/lit/gpn/ucc28781
[28] Richtek. RT7740MA. "SmartJitter Multi-Mode Flyback Controller" [Online]. Available:https://www.richtek.com/Products/AC_DC/Flyback%20Controller/RT7740MA?sc_lang=en
[29] Leadtrend. LD5523. "Multi-Mode PWM Controller of Flyback with Integrated BNI/BNO and Protection"[Online]. Available: https://www.leadtrend.com.tw/images/cgcustom/img020201214171915.pdf
[30] Power Intergrations, InnoSwitch3-CE [Online]. Available: https://www.power.com/sites/default/files/documents/innoswitch3-ce_family_datasheet_TW.pdf
[31] Richtek. RT7790. " Advanced PWM Controller for Programmable Power Converter"[Online].Available: https://www.richtek.com/Products/AC_DC/Flyback%20Controller/RT7790?sc_lang=zh-TW
[32] Analog Devices.ADuM246XA"Quad-Channel Isolators with Integrated DC-to-DC Converter" [Online]. Available: https://www.mouser.tw/datasheet/2/609/adum6420a_6421a_6422a_6423a_6424a-2401156.pdf
[33] Texas Instruments. UCC21737-Q1. " Automotive 10-A Source and Sink Reinforced Isolated Single Channel Gate Driver for SiC/IGBT with Active Protection and High-CMTI"[Online].Available: https://www.ti.com/lit/ds/symlink/ucc21737-q1.pdf
[34] MPS, MPX2001. " All-in-One Flyback Controller with Integrated Primary and Secondary Synchronous Rectification Driver with Capactive Isolation"
[35] Texas Instruments. "Keep Noise Out of Your System and Eliminate Ground Loops: How to Choose the Right Isolator" [Online]. Available: https://www.ti.com/lit/ml/sllp108/sllp108.pdf
[36] Renesas. "Current Transfer Ratio (CTR) and Response Time of Photocouplers / Optocouplers"[Online]. Available: https://www.renesas.com/us/en/products/interface-connectivity/optoelectronics/current-transfer-ratio-ctr-and-response-time-photocouplers-optocouplers
[37] Y. Xiong, S. Sun, H. Jia, P. Shea and Z. John Shen, "New Physical Insights on Power MOSFET Switching Losses," in IEEE Transactions on Power Electronics, vol. 24, no. 2, pp. 525-531, Feb. 2009
[38] K. H. Liu, R. Oruganti, and F. C. Y. Lee, "Quasi-Resonant Converters-Topologies and Characteristics," IEEE Transactions on Power Electronics, vol. PE-2, no. 1, pp. 62-71, 1987.
[39] Texas Instruments. " Control and Design Challenges for Synchronous Rectifier" [Online]. Available: https://www.ti.com/seclit/ml/slup378/slup378.pdf
[40] J. Park, Y. -S. Roh, Y. -J. Moon and C. Yoo, "A CCM/DCM Dual-Mode Synchronous Rectification Controller for a High-Efficiency Flyback Converter," in IEEE Transactions on Power Electronics, vol. 29, no. 2, pp. 768-774, Feb. 2014
[41] Y. Kubota, K. Nishimura and K. Kobayashi, "Synchronous rectification circuit using a current transformer," INTELEC. Twenty-Second International Telecommunications Energy Conference (Cat. No.00CH37131), 2000
[42] Texas Instruments. "Boost Efficiency for Low Cost Flyback Converters"[Online]. Available: https://www.edn.com/wp-content/uploads/2008/04/4.3.08-MS.pdf
[43] System General, "PWM controller for synchronous rectifier of flyback power converter" Patent US20060018135A1, 2006
[44] Texas Instruments. UCC24630. " Synchronous Rectifier Controller With Ultra-Low-Standby Current" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc24630.pdf
[45] Fairchild. FAN6224. " Synchronous Rectification Controller for Flyback and Forward Freewheeling Rectification" [Online]. Available: https://www.mouser.com/datasheet/2/149/FAN6224-76873.pdf
[46] W. Langeslag, R. Pagano, K. Schetters, A. Strijker and A. van Zoest, "VLSI Design and Application of a High-Voltage-Compatible SoC–ASIC in Bipolar CMOS/DMOS Technology for AC–DC Rectifiers," in IEEE Transactions on Industrial Electronics, vol. 54, no. 5, pp. 2626-2641, Oct. 2007
[47] K. Yoshida, T. Ishii and N. Nagagata, "Zero voltage switching approach for flyback converter," [Proceedings] Fourteenth International Telecommunications Energy Conference - INTELEC '92, 1992, pp. 324-329, doi: 10.1109/INTLEC.1992
[48] R. Watson, F. C. Lee and G. C. Hua, "Utilization of an active-clamp circuit to achieve soft switching in flyback converters," in IEEE Transactions on Power Electronics, vol. 11, no. 1, pp. 162-169, Jan. 1996
[49] M. T. Zhang, M. M. Jovanovic and F. C. Y. Lee, "Design considerations and performance evaluations of synchronous rectification in flyback converters," in IEEE Transactions on Power Electronics, vol. 13, no. 3, pp. 538-546, May 1998
[50] Texas Instruments. "Zero-Voltage-Switching Flyback Using UCC28780 Controller and UCC5304 Isolated Synchronous Rectifier Driver" [Online]. Available: https://www.ti.com/lit/an/sluaa60/sluaa60.pdf
[51] X. Huang, W. Du, W. Yuan, J. Zhang and Z. Qian, "A novel variable frequency soft switching method for Flyback converter with synchronous rectifier," 2010 Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2010
[52] A. Connaughton, A. P. Talei, K. K. Leong, K. Krischan and A. Muetze, "Investigation of a Soft-Switching Flyback Converter With Full Secondary Side-Based Control," in IEEE Transactions on Industry Applications, vol. 53, no. 6, pp. 5587-5601, Nov.-Dec. 2017
[53] Texas Instruments.UCC28780 "High Frequency Active Clamp Flyback Controller" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc28780.pdf
[54] Texas Instruments.UCC24612 " High Frequency Synchronous Rectifier Controller" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc24612.pdf
[55] W. -H. Chang et al., "Highly Integrated ZVS Flyback Converter ICs With Pulse Transformer to Optimize USB Power Delivery for Fast-Charging Mobile Devices," in IEEE Journal of Solid-State Circuits, vol. 55, no. 12, pp. 3189-3199, Dec. 2020
[56] Texas Instruments.UCC28740 " Constant-Voltage Constant-Current Flyback Controller Using Optocoupled Feedback" [Online]. Available: https://www.ti.com/lit/ds/symlink/ucc28740.pdf
[57] C. Zhao, X. Xie, H. Dong and S. Liu, "Improved Synchronous Rectifier Driving Strategy for Primary-Side Regulated (PSR) Flyback Converter in Light-Load Mode," in IEEE Transactions on Power Electronics, vol. 29, no. 12, pp. 6506-6517, Dec. 2014
[58] H. Dong, X. Xie and L. Zhang, "A New CCM/DCM Hybrid-Mode Synchronous Rectification Flyback Converter," in IEEE Transactions on Industrial Electronics, vol. 67, no. 5, pp. 3629-3639, May 2020
[59] Texas Instruments.UCC24610 " GREEN Rectifier™ Controller Device" [Online]. Available: http://www.ti.com/lit/ds/symlink/ucc24610.pdf
[60] On Semiconductors. NCP4302"Secondary Side Synchronous Flyback Controller" [Online]. Available: https://www.onsemi.com/pdf/datasheet/ncp4302-d.pdf
[61] Power Integrations, " Secondary controller for use in synchronous flyback converter" Patent US20140204625A1, 2014
[62] Xuefei Xie, J. C. P. L. Liu, F. N. K. Poon and Man Hay Pong, "Current-driven synchronous rectification technique for flyback topology," 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230), 2001
[63] Xie Xuefei, J. C. P. Liu, F. N. K. Poon and B. M. H. Pong, "Two methods to drive synchronous rectifiers during dead time in forward topologies," APEC 2000. Fifteenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.00CH37058), 2000
[64] Leadtrend. LD8523 " Synchronous Rectification Driver with Green Mode Function" [Online]. Available: https://www.leadtrend.com.tw/images/cgcustom/img020201217155231.pdf
[65] E. Sakai and K. Harada, "A new synchronous rectifier using bipolar transistor driven by current transformer," [Proceedings] Fourteenth International Telecommunications Energy Conference - INTELEC '92, 1992
[66] L. Huber and M. M. Jovanović, "Small-signal analysis of DCM flyback converter in frequency-foldback mode of operation," 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2013
[67] Y. Panov and M. M. Jovanovic, "Performance evaluation of 70-W two-stage adapters for notebook computers," APEC '99. Fourteenth Annual Applied Power Electronics Conference and Exposition. 1999 Conference Proceedings (Cat. No.99CH36285), 1999
[68] A. Prodic, D. Maksimovic and R. W. Erickson, "Digital controller chip set for isolated DC power supplies," Eighteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2003. APEC '03., 2003
[69] Analog Devices, "Anatomy of a Digital Isolator" [Online]. Available: https://www.analog.com/media/en/technical-documentation/tech-articles/MS-2234.pdf
[70] Monolithic Power Systems, "Capacitive Isolation: A Fundamental Building Block in Future AC/DC Power Conversion" [Online]. Available: https://www.monolithicpower.com/en/capacitive-isolation-article
[71] Fairchild. "Design Guidelines for RCD Snubber of Flyback Converters" [Online]. Available: https://www.fairchildsemi.com/application-notes/AN/AN-4147.pdf
[72] Infineon. "Design Guide for Off-line Fixed Frequency DCM Flyback Converter" [Online]. Available: https://www.mouser.com/pdfdocs/2-8.pdf
[73] ROHM. "設計絕緣型返馳式轉換器電路：決定主要零件－MOSFET相關之1" [Online]. Available: https://techweb.rohm.com.tw/knowledge/acdc/acdc_pwm/acdc_pwm01/1221
[74] ROHM. "設計絕緣型返馳式轉換器電路：決定主要零件－MOSFET相關之2"[Online]. Available:https://techweb.rohm.com.tw/knowledge/acdc/acdc_pwm/acdc_pwm01/1261
[75] ROHM. "Advantages of USB PD "[Online]. Available: https://www.rohm.com/electronics-basics/usbpd/advantage-of-usbpd
[76] Linkedin. " What is USB-C and USB-C Power Delivery(PD) " [Online]. Available: https://www.linkedin.com/pulse/what-usb-c-power-deliverypd-gill-zhu
[77] Marian K. Kazimierczuk . "Pulse-Width Modulated DC-DC Power Converters "WILEY, 2008
[78] Fairchild. "AN-6094 Design Guideline for Flyback Charger Using FAN302HL/UL" [Online]. Available: https://www.onsemi.jp/pub/collateral/an-6094jp.pdf
[79] Texas Instruments. "Grounding in mixed-signal systems demystified"[Online]. Available: https://www.ti.com/lit/an/slyt499/slyt499.pdf
[80] Hank Zumbahlen. "Linear Circuit Design Handbook Ch 12: Printed Circuit Board (PCB)Design Issues" Newnes/Elsevier, 2008
[81] J. Park et al., "Quasi-Resonant (QR) Controller With Adaptive Switching Frequency Reduction Scheme for Flyback Converter," in IEEE Transactions on Industrial Electronics, vol. 63, no. 6, pp. 3571-3581, June 2016
[82] Y. -C. Kang, C. -C. Chiu, M. Lin, C. -P. Yeh, J. -M. Lin and K. -H. Chen, "Quasiresonant Control With a Dynamic Frequency Selector and Constant Current Startup Technique for 92% Peak Efficiency and 85% Light-Load Efficiency Flyback Converter," in IEEE Transactions on Power Electronics, vol. 29, no. 9, pp. 4959-4969, Sept. 2014
[83] C. -J. Chen, C. -H. Cheng, P. -S. Wu and S. -S. Wang, "Unified Small-Signal Model and Compensator Design of Flyback Converter With Peak-Current Control at Variable Frequency for USB Power Delivery," in IEEE Transactions on Power Electronics, vol. 34, no. 1, pp. 783-793, Jan. 2019
[84] C. -H. Cheng, C. -J. Chen and S. -S. Wang, "Small-Signal Model of Flyback Converter in Continuous-Conduction Mode With Peak-Current Control at Variable Switching Frequency," in IEEE Transactions on Power Electronics, vol. 33, no. 5, pp. 4145-4156, May 2018
[85] Fairchild. FAN6862 " Highly Integrated Green-Mode PWM Controller"[Online]. Available: https://www.onsemi.com/pdf/datasheet/fan6862-d.pdf
[86] Leadtrend. LD5523 "Multi-Mode PWM Controller of Flyback with Integrated BNI/BNO and Protection "[Online]. Available: https://www.leadtrend.com.tw/images/cgcustom/img020201214171915.pdf
[87] R. W. Farrington, C. Svardsjo, and W. Hart, "Externally-driven scheme for synchronous rectification " U.S. Patent US 6188592 B1, Feb. 13, 2001
[88] NXP Semiconductors. TEA1761t " GreenChip synchronous rectifier controller"[Online]. Available: https://www.nxp.com/docs/en/data-sheet/TEA1761T.pdf
[89] Richtek. "返馳式轉換器之等效集總電容分析" [Online]. Available: https://www.richtek.com/Design%20Support/Technical%20Document/AN054?sc_lang=zh-TW
[90] Donglie Gu, Jianxiong Xi, Lenian He, A synchronous rectified flyback AC-DC converter using capacitor-coupled isolated communication, IEICE Electronics Express, 2020
[91] Sun, S., Guo, H., Zhang, Y., Sun, L., Li, Y., Zhang, Y.: Novel synchronous rectification strategy for flyback converter in both DCM and CCM applications. IET Power Electron. 00, 1– 12 (2022).
[92] L. Xue and J. Zhang, "Highly Efficient Secondary-Resonant Active Clamp Flyback Converter," in IEEE Transactions on Industrial Electronics, vol. 65, no. 2, pp. 1235-1243, Feb. 2018
[93] C. -C. Kuo et al., "A Dynamic Resonant Period Control Technique for Fast and Zero Voltage Switching in GaN-Based Active Clamp Flyback Converters," in IEEE Transactions on Power Electronics, vol. 36, no. 3, pp. 3323-3334, March 2021
[94] Gu, Donglie; Xi, Jianxiong; He, Lenian: "Digitally controlled GaN-based MHz active clamp flyback converter with dynamic dead time optimisation for AC–DC adapter", IET Power Electronics, 2020
[95] X. Huang, W. Du, W. Yuan, J. Zhang and Z. Qian, "A novel variable frequency soft switching method for Flyback converter with synchronous rectifier," 2010 Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2010
[96] X. Xie, J. Zhang, C. Zhao and Z. Qian, "An Improved Current-Driven Method for Synchronous Flyback AC/DC Converters," INTELEC 06 - Twenty-Eighth International Telecommunications Energy Conference, 2006
[97] H. Dong, X. Xie and L. Zhang, "A New Primary PWM Control Strategy for CCM Synchronous Rectification Flyback Converter," in IEEE Transactions on Power Electronics, vol. 35, no. 5, pp. 4457-4461, May 2020
[98] Texas Instruments. " Flyback Selection Guide" [Online]. Available: https://www.ti.com/lit/an/sluaae5/sluaae5.pdf
[99] Texas Instruments. UCC28742. " High-Efficiency Flyback Controller with Optocoupler Feedback" [Online]. Available:http://www.ti.com/lit/ds/symlink/ucc28742.pdf