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New Bridgeless Buck PFC Converter With Improved Input Current And Power Factor

Abstract The Bridgeless Buck Power Factor Correction (PFC) Converters Feature The Merits Of Low Output Voltage And High Efficiency While Their Nature Existing Dead Angles In The Input Current Deteriorate The Input Current Harmonics And Power Factor (PF). Aiming To Reduce The Dead Angles, A New Bridgeless Buck PFC Converter Is Proposed In This Paper. Through Integrating The Main Buck Circuit And The Auxiliary Flyback Circuit With One Magnetic Core, The Dead Angles In Input Current Of The Proposed Bridgeless Buck PFC Converter Is Eliminated So That The Power Factor And Input Current Harmonics Are Improved. The Proposed Bridgeless Buck PFC Converter Is Designed To Operate In Discontinuous Conduction Mode (DCM) With The Merits Of Simple Controller And Nature Current Shaping Ability. A New Logic Control Circuit Is Provided. The Detailed Theoretical Derivations And Design Consideration Are Presented. The Experimental Comparison Among The Proposed Bridgeless Buck PFC Converter, The Conventional Buck PFC Converter And The Conventional Bridgeless Buck PFC Converter Is Displayed To Validate The Effectiveness Of The New Converter.

Flexible Mode Bridgeless Boost PFC Rectifier With High Efficiency Over A Wide Range Of Input Voltage

A Novel FMBL PFC Rectifier Is Proposed, In Which The High Efficiency Over A Wide Input Range Can Be Achieved. In The Proposed Rectifier, A BTBBL PFC Rectifier Is Adopted At High-line Voltages And A Three-level Bridgeless Boost PFC Rectifier (TLBL PFC) Is Formed To Achieve High Efficiency At Low-line Voltages. Compared With The Traditional Bridgeless Boost PFC Rectifier, An Extra Low-voltage Bidirectional Switch (usually Composed Of Two Switches) Is Added; Therefore The Increased Cost Is Low. At Both High- And Low-line Conditions, The Low CM Noise Can Be Achieved Due To The Direct Connection Between The Input Power Grid And The Output Electrolytic Capacitor During Half-line Cycle. The Proposed FMBL PFC Can Be Simply Treated As Two Independent Boost PFC Circuits According To The Line Voltage.

Power Quality Improvement Using Four Leg Three Level NPC Inverter And Second Order Sliding Mode Control

In This Project, A Second Order Sliding Mode Controller Is Proposed For The Power Flow Control Of A HESS, Using A Four Leg Three Level Neutral Point Clamped (4-Leg 3LNPC) Inverter As The Only Interface Between The RES/HESS And The Microgrid. A Three-dimensional Space Vector Modulation And A Sequence Decomposition Based AC Side Control Allows The Inverter To Work In Unbalanced Load Conditions While Maintaining A Balanced AC Voltage At The Point Of Common Coupling. DC Current Harmonics Caused By Unbalanced Load And The NPC Floating Middle Point Voltage, Together With The Power Division Limits Are Carefully Addressed In This Paper. The Effectiveness Of The Proposed Technique For The HESS Power Flow Control Is Compared To A Classical PI Control Scheme And Is Proven Through Simulations And Experimentally Using A 4 Leg 3LNPC Prototype On A Test Bench.

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