ABSTRACT:
A
current-fed zero-voltage-switching (ZVS) and zero-current-switching (ZCS)
CL-resonant push–pull dc – dc converter is presented in this paper. The
proposed push–pull converter topology is suitable for unregulated low-voltage
to high-voltage power conversion with low ripple input current. The resonant frequency
of both capacitor and inductor is operated at approximately twice the main
switching frequency. In this topology, the main switch is operated under ZVS
because of the commutation of the transformer magnetising current and the
parasitic drain–source capacitance. Because of the leakage inductance of the transformer
and the resonant capacitance from the resonant circuit, both the main switch
and output rectifier are operated by implementing ZCS. The operation and
performance of the proposed converter has been verified on a 400-W prototype.
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Figure
1 Schematic diagram of the proposed current-fed ZVS–ZCS CL-resonant push–pull
dc–dc converter
EXPECTED SIMULATION RESULTS:
Figure
2 Measured waveforms of gate to source voltage and drain to source voltage a
ZVS operations for Q1 and Q2 at the full load b Expanded scale of Fig. 7a in
point A
Figure 3 ZCS operations for Q1 and Q2 at
the full load
Figure
4 ZCS operations for rectifier diode at the full load
Figure
5 Waveforms of vin, iin, ip and icr at the full load
Figure
6 Waveforms with excessive dead time
Figure
7 Step change with resistance load
a
Load connection
b
Load disconnection
CONCLUSION:
This
study proposed, analysed, and quantified a current-fed ZVS–ZCS CL-resonant
push–pull dc–dc converter that utilises the commutation of the transformer magnetizing
current and the parasitic drain–source capacitance to obtain the main switch to
be operated under ZVS. By using the leakage inductance of a transformer and resonant
capacitor, a sinusoidal current is formed in this resonant circuit by turning
on and off the switch. Thus, both the main switch and the output rectifier can
be operated under ZCS. Because this proposed converter includes an input
inductance, the input terminal of the converter cannot be added with a filter.
This converter can reach a steady state with a small ripple input current, which
is especially suitable for unregulated dc–dc conversion from a low-voltage
high-current source. From the experimental results, the main switch can be
operated using both ZVS and ZCS and the output rectifier can be operated using
ZCS. The operating principles and theoretical analysis of this proposed
converter were verified by using a 400-W and 65-kHz prototype. The overall
efficiency of the converter nearly reached 93% at full output power.
REFERENCES:
[1]
SHOYAMA M., HARADA K.: ‘Steady-state characteristics of the push-pull dc-to-dc
converter’, IEEE Trans. Aerosp. Electron. Syst., 1984, 20, (1), pp. 50–56
[2]
THOTTUVELIL V.J., WILSON T.G., QWEN H.A.: ‘Analysis and design of a push-pull
current-fed converter’. Proc. IEEE PESC, 1981, vol. 5, pp. 192–203
[3]
REDL R., SOKAL N.: ‘Push –pull current-fed, multiple output regulated wide
input range dc/dc power converter with only one inductor and with 0 to 100% switch
duty ratio: operation at duty ratio below 50%’. Proc. IEEE PESC, 1981, pp.
204–212
[4]
WILDON C.P., DE ARAGAO F., BARBI I.: ‘A comparison between two current-fed
push-pull dc-dc converters – analysis, design and experimentation’. Proc. IEEE
INTELEC, 1996, pp. 313–320
[5]
YING J., ZHU Q., LIN H., WU Z.: ‘A zero-voltage-switching (ZVS) push-pull dc/dc
converter for UPS’. Proc. IEEE PEDS, 2003, pp. 1495–1499
