Analysis and Design of Bridgeless Boost Totem Pole Converter for Power Factor Correction Application Operating in CRM and DCM Mode

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Hameed, Aamna Nasir
Electrical Engineering , Power Electronics , Power Converters , AC to DC Converters , Power Factor Correction , Discontinuous Condition Mode , Critical Conduction Mode
With an increased demand for consumer electronics such as laptops or small electrical vehicles, the need for medium power portable chargers is drastically increasing. The first stage of these chargers is the power factor correction (PFC) part which reduces the total harmonic distortion (THD) in the input current to improve the power quality. This thesis document presents a 180 W PFC design that is more efficient than other PFC designs with a similar power rating and operates in Discontinuous Condition Mode (DCM) and Critical Conduction Mode (CrM). The proposed PFC design is a Bridgeless Totem Pole Boost PFC that has a low component count, simple design, and dynamic control. The on-time of the main switch is constant in one half Alternating Current (AC) line cycle which enhances the power factor by reducing the distortion in the input current. Moreover, the computation time and complexity of the control loop is reduced as unlike most designs the suggested PFC design does not have a current feedback loop. The designed PFC implements real time Synchronous Rectifier (SR) switch on time calculation which improves efficiency by eliminating the turn off switching loss of the SR switch. A power loss analysis is carried out at full load for 120 Vac and 220 Vac. The estimated efficiency at 120 Vac is 97.9% whereas, at 220 Vac it is 98.6%. Additionally, the input current harmonics for the Bridgeless Totem Pole Boost PFC are analyzed and compared with the IEC 61000-3-2 standards. The experimental verification is done for the universal input voltages at full load of 180 W whereas, at 120 Vac and 220 Vac a light load to full load sweep is carried out. At 120 Vac a full load efficiency of 97.3% is achieved with a high-power factor of 0.992. At 220 Vac the full load efficiency is measured to be 98.0% with a 0.944 power factor. It is observed that the measured input harmonic current stays below the calculated maximum allowed harmonic current at all load values.
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