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A Buck Power Factor Correction Converter
with Predictive Quadratic Sinusoidal Current
Modulation and Line Voltage Reconstruction
Abstract:
A buck Power Factor Correction (PFC) converter operating in Continuous
Conduction Mode (CCM) is influenced by the dead zone which introduces distortion
related to the input line voltage. Such phenomenon limits the maximum Power
Factor(PF) and minimum Total Harmonic Distortion (THD) achievable. By deriving
a methodology to achieve predictive line voltage reconstruction (PLVR), the
influence of the dead zone is mitigated. With the prediction of Quadratic Sinusoidal
Current Modulation (PS2CM), the input line current is shaped into sinusoid
waveform which is in-phase with input line voltage, crucial for. Consequently, the
proposed CCM buck PFC can achieve high PF, low THD, and efficiency
simultaneously. A test chip was fabricated in 0.5μm BCD process. Experimental
results
show a peak PF of 0.95 and a peak efficiency of 98% at 110Vac.
Existing System:
 The magnitude of the output voltage, VOUT, is directly associated with the
efficiency of the overall buck PFC.
 Unfortunately, the averaged input current is pinched off when VLINE < VOUT,
creating a dead zone td.
 The distortion induced by the discontinuity td is proportional to VOUT and
increases the overall THD of the buck PFC.
 It is possible to add additional switches to the buck PFC to resolve td and to
improve THD, but this approach comes at the price of lower efficiency and
defeats the purpose of choosing the buck PFC over the
boost PFC topology.
Disadvantage:
 Large passive devices are required hence overall cost of the system is high.
 Unwanted Electromagnetic Interference (EMI) is induced.
 Overall THD rate is high.
Proposed System:
 The proposed buck PFC operates in CCM with an Average Current Mode Control
(ACM).
 The proposed buck PFC is designed using the Predictive Line Voltage
Reconstruction (PLVR) technique, which reconstructs the line voltage
independent of the dead zone by predictive reconstruction and sample and hold
operations.
 Through the predictive calculation of Quadratic Sinusoidal Current Modulation
(PS2CM), which is a technique very different from the sine current modulation
used in boost-type PFC converters, the input current IIN is shaped to a quadratic
sinusoidal wave to reduce the input THD by an analog calculation circuit.
Advantage:
 A 0.95 PF and 18% THD buck CCM PFC is proposed with
PS^2CM and PLVR techniques.
 The proposed CCM buck PFC operating in the ACM operation reduces peak
current while maintaining high power factor by resolving the distortion, which is
attractive for high-power PFC applications.
 Performance of Electromagnetic Interference (EMI) is improved.
Circuit Diagram:
(Architecture of the ACM control buck PFC converter with the proposed
PS2CM and PLVR techniques)
References:
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only two active switches,” IEEE Trans. Ind. Electron., vol. 62, no. 5, pp.2795 - 2806,
May 2015.
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adaptive nonlinear current observer for boost PFC AC/DC converters,”
IEEE Trans. Ind. Electron., vol. 61, no. 12, pp.6720–6729, Sept. 2014.
[3] V. Sype, M. David, K. Gusseme, V. Bossche, and J. A. Melkebeek,
“Duty-ratio feedforward for digitally controlled boost PFC converters,”
IEEE Trans. Ind. Electron., vol. 52, no. 1, pp. 108 - 115, Jan. 2005.
[4] F. Zhang and J. Xu, “A novel PCCM boost PFC converter with fast
dynamic response,” IEEE Trans. Ind. Electron., vol. 58, no. 9, pp. 4207
-4216, Sept. 2011.
[5] H.-S. Kim, J.-K. Kim, K.-B. Park, H.-W. Seong, G.-W. Moon, and
M.-J. Youn, “On/off control of boost PFC converters to improve lightload efficiency in paralleled power supply units for servers,” IEEE
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