wiwo dc dc converter
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WIWO DC-DC CONVERTER
INTRODUCTION
BASIC DC-DC CONVERTERS:
• BUCK CONVERTER
• BOOST CONVERTER
• CUK CONVERTER
• BUCK-BOOST CONVERTER
NEED FOR A NEW SWITCHING CONVERTER ?
MOTIVATION IN THE SEARCH FOR NEW SWITCHING CONVERTER
• The basic buck and boost converters can be
transformed into a number of new topologies by bringing in the tapped inductor.
• The proposed tapped-inductor buck-derived & boost derived converters are shown with their corresponding voltage conversion ratios.
Fig.1 Buck-derived converters with tapped inductors
Fig.2 Voltage conversion ratio of buck-derived converters with tapped inductors. (a) 0 < n < ∞ (b) 0 < n < ∞ (c) n > 1 (d) n > 1.
Fig.3 Boost derived inductors with tapped inductors
Fig.4.Voltage conversion ratio of boost-derived converters with tapped inductors (a) 0 < n < ∞ (b) 0 < n < ∞ (c) 0 < n <1 (d) 0 < n < 1.
• From the conversion ratio plot, the converters of Fig.1(a) & 3(a) has wider step-down & step-up responses.
• These two topologies may be combined to form a new two-switch topology, with an extended conversion range.
WIWO DC-DC CONVERTER
Fig.5.Proposed Wide-Input-Wide-Output DC-DC converter
• Wide-Input-Wide-Output (WIWO) DC-DC converter is an integration of buck and boost converters via a tapped inductor.
• It can operate in both buck mode & boost mode.
• Buck Mode:
Switch S1 is assigned a high-frequency switching signal & whereas S2 is switched complementarily to S1. The diode D is kept ON by the inductor L2 current.
• Boost Mode:
Switch S2 made continuously ON and it issues the required duty cycle signal for the S1 switch & diode D is forced to switch on and off complementarily to S1.
• Transition between step-down and step-up modes is achieved by a proper control scheme.
CONTROL SCHEME
• For proper operation of WIWO, PWM control circuitry is used.
• Vm is the magnitude of sawtooth wave.
• Control voltage Vc=mVm.
• Buck Mode: 0 ≤ m < 1• Boost Mode: 1 ≤ m ≤ 2
Fig.6 WIWO control circuitry
OPERATING PRINCIPLE
Fig.7 Four states of the WIWO converter. (a) Buck-mode charging state. (b) Buck-mode discharging state (c) Boost-mode charging state
(d) Boost-mode discharging state.
Fig.8 Waveforms of the WIWO dc–dc converter. (a) Buck mode. (b) Boost mode.
VOLTAGE TRANSFER CHARACTERISTICS
• For n = 1, the voltage transfer ratio is smooth , where as for other values of n, the curves exhibit a slope change.
• The buck to boost switch over point is at m = 1.Fig.9 Voltage transfer characteristics
APPLICATIONS
• WIWO DC–DC CONVERTER WITH THE SYNCHRONOUS RECTIFIER
Fig.10 WIWO DC–DC converter with the synchronous rectifier
• BIDIRECTIONAL WIWO DC–DC CONVERTER
Fig.11 Bidirectional WIWO DC–DC converter
• WIWO PFC AC–DC CONVERTER
Fig.12 Waveforms passing through WIWO DC-DC converter PFC circuit
CONCLUSION
• WIWO is an integration of buck and boost converters.
• It retains the features of both the buck and the boost converters.
• It achieves wider step-up and wider step-down DC-DC conversion range.
• It has a simple structure and moderate component count.
• The transition between the operating modes is inherently smooth, and causes no transient disturbance.
BIBLIOGRAPHY
• Hao Cheng, Keyue Ma Smedley, “A Wide –Input-Wide-Output(WIWO)DC-DCConverter”,vol.25,no.2, February 2010.
• H. Cheng and K. Smedley, “Wide input wide output (WIWO) dc–dc converter,”in Proc. IEEE Appl. Power Electron. Conf. Expo., 2008.
• J.-H. Park and B.-H. Cho, “Non isolation soft-switching buck converter with tapped-inductor for wide-input extreme step-down applications,”IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 54, no. Aug. 2007.
THANK YOU
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