- Volume 16 Issue 3
A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.
AC-DC converter;Constant current;Inductance compensation;PFM;Primary-side regulation
- J. W. Shao, "A highly accurate constant voltage (CV) and constant current (CC) primary side controller for offline applications," in 28th Annual IEEE Applied Power Electronics Conference and Exposition(APEC), pp. 3311-3316, 2013.
- C.-N. Wu, Y.-M. Chen, and Y.-L Chen, "High-precision constant output current control for primary-side regulated flyback converters," in 28th Annual IEEE Applied Power Electronics Conference and Exposition(APEC), pp. 3092-3095, 2013.
- J. Zhang, T. Jiang, L. Xu, and X. Wu, “Primary side constant power control scheme for LED drivers compatible with TRIAC dimmers,” Journal of Power Electronics, Vol. 13, No. 4, pp. 609-618, Jul. 2013. https://doi.org/10.6113/JPE.2013.13.4.609
- Y.-T. Lin, T.-J. Liang, and K.-H. Chen, "IC design of primary-side control for flyback converter," in 1st International Future Energy Electronics Conference(IFEEC), pp. 449-453, 2013.
- Y. Chen, C. Chang, and P. Yang, “A novel primary-side controlled universal-input AC-DC LED driver based on source driving control scheme,” IEEE Trans. Power Electron., Vol. 30, No. 8, pp. 4327-4335, Aug. 2015. https://doi.org/10.1109/TPEL.2014.2359585
- J. Zhang, X. Huang, X. Wu, and Z. Qian, “A high efficiency flyback converter with new active clamp technique,” IEEE Trans. Power Electron., Vol. 25, No. 7, pp. 1775–1785, Jul. 2010. https://doi.org/10.1109/TPEL.2010.2042302
- Y. Panov and M. Jovanovic, "Small-signal analysis and control design of isolated power supplies with optocoupler feedback," in 19th Annual IEEE Applied Power Electronics Conference and Exposition(APEC), Vol. 2, pp. 777-785, 2004.
- S. Hamamura, D. Kurose, T. Ninormiya, and M. Yamamoto, "Piezoelectric transformer AC-DC converter over a worldwide range of input voltage by combined PWM and PFM control," in IEEE Power Electronics Specialists Conference, Vol. 1, pp. 416-421, 2001.
- T. Jiang, H. Zeng, J. Zhang, and Z. Qian, "A primary side feedforward control scheme for low power LED driver compatible with triac dimmer," in 27th Annual IEEE Applied Power Electronics Conference and Exposition(APEC), pp. 963-968, Feb. 2012.
- S. Huynh, M. Grant, and D. Kunst, "Adjusting inductor switching frequency to compensate for inductance that deviates from a stated magnitude in order," U.S. Patent No. 7667987 B2, Jul. 26, 2010.
- L. F. Shi, X. Q. Lai, Z. Cai, Q. Ye, and H. S. He, "Primary inductance correction circuit applied to flyback switching power supply," C.N. Patent No. CN 102255502 B, 2014.
- R. Nalepa, N. Barry, and P. Meaney, "Primary side control circuit of a flyback converter," in 16th Annual IEEE Applied Power Electronics Conference and Exposition(APEC), Vol. 1, pp. 542-547, 2001.