ABSTRACT
This
paper proposes an asymmetric forward-flyback dc-dc converter that has high
power-conversion efficiency ηe over a wide output power range. To solve
the problem of ringing in the voltage of the rectifier diodes and the problem
of duty loss in the conventional asymmetric half-bridge (AHB) converter, the
proposed converter uses a voltage doubler structure with a forward inductor Lf
in the second stage, instead of using the transformer leakage inductance,
to control output current. Lf resonates with the capacitors in the
voltage doubler to achieve a zero-voltage turn-on of switches and a
zero-current turn-off of diodes for a wide output power range. The proposed
converter could operate at a wider input voltage range than the other AHB
converters. ηe was measured as 95.9% at output power PO = 100 W
and as 90% at PO = 10 W, when the converter was operated at input
voltage 390 V, output voltage 142 V, and switching frequency 100 kHz.
KEYWORDS
1.
DC-DC power conversion
2.
Resonance
3.
Stress
4.
Transformer windings
SOFTWARE:
MATLAB/SIMULINK
CIRCUIT DIAGRAM:
EXPECTED SIMULATION RESULTS
Fig. 2. Voltage and current waveforms of switches of the proposed
converter
at (a) PO = 100 W and (b) PO = 10 W.
Fig. 3. Voltage and current waveforms of D1 and
D2 at PO = 100 W: (a) the proposed converter, (b) the
conventional AHB converter, and (c) the converter of [20].
CONCLUSION
The
proposed asymmetric forward-flyback dc-dc converter had high power conversion
efficiency ηe for a wide range of output power PO. The problems
of voltage ringing and duty loss in the conventional AHB converter was solved by
adopting a forward inductor Lf in the voltage doubler circuit of the
secondary stage. The proposed converter used an unbalanced secondary turns of
transformer which allowed it to operate for a much wider range of input voltage
than the other converter [20] that uses a voltage doubler structure in the
secondary stage. The proposed converter also reduced the voltage stress on
switches and the current stress on diodes significantly compared to the dual
resonant converter (the converter of [24]). The proposed converter had ηe ≥
90% for 10 ≤ PO ≤ 100 W at VIN = 390 V, VO = 142 V, and fS
= 100 kHz (the highest ηe = 95.9%, at PO = 100 W), and could
operate at 330 ≤ VIN ≤ 440 V. The proposed asymmetric forward-flyback
dc-dc converter is a good candidate for developing a step-down dc-dc converter
for applications that require high power-conversion efficiency over wide ranges
of input voltage and output power.
REFERENCES:
[1] J. B. Lio, M.
S. Lin, D. Y. Chen, and W. S. Feng, “Single-switch soft-switching flyback
converter,” Electron. Letter, vol. 32, no. 16, pp. 1429-1430, Aug. 1996.
[2] A. Abramovitz,
C. S. Liao, and K. Smedley, “State-Plane analysis of regenerative snubber for
flyback converters,” IEEE Trans. Power Electron., vol. 28, no. 11, pp.
5323-5332, Nov. 2013.
[3] L. Huber, and
M. M. Jovanovic, “Evaluation of flyback topologies for notebook AC/DC
adapter/charger applications,” in Proc. High Freq. Power Conversion Conf.,
1995, pp. 284-294.
[4] S. Du, F. Zhu,
and P. Qian, “Primary side control circuit of a flyback converter for HBLED,”
in Proc. 2nd IEEE Int. Symp. Power Electron. Distrib. Generation Syst.,
2010, pp. 339-342.
[5]
E. S. Kim, B. G. Chung, S. H. Jang, M. G. Choi, and M. H. Kye, “A study of
novel flyback converter with very low power consumption at the standby
operation mode,” in Proc. IEEE Appl. Power Electron. Conf., 2010, pp.
1833-1837
