Bridgeless PFC Converter with Interleaved Switching Cells

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Solution Overview

Problem

Conventional bridgeless power factor correction (PFC) boost converters suffer from severe electromagnetic interference (EMI) noise and efficiency degradation due to parasitic capacitance and conduction losses, particularly in high-power applications.

Innovation Solution

A bridgeless PFC boost converter design featuring either a single or two interleaved switching cells operating 180 degrees out of phase, with optimized configurations of transistor switches and diodes to reduce semiconductor devices in the current path, replacing freewheeling diodes with transistor switches to enhance efficiency and EMI performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional bridgeless PFC boost converters use rectifying diodes in the current path, then the circuit structure is simpler, but conduction losses increase and efficiency degrades

Engineering Contradiction:

Improvecircuit structureVSAvoidconduction losses

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent changes the key parameter of the rectifying element from diode to transistor switch. This parameter change enables lower on-state resistance and reduced conduction losses while maintaining the bridgeless circuit structure, directly resolving the contradiction between structural simplicity and energy efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the rectifying diode (semiconductor rectification mechanism) with a transistor switch (controlled switching mechanism). This substitution allows for lower resistance and reduced power loss, addressing the efficiency degradation caused by diode conduction losses

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If conventional bridgeless PFC boost converters use rectifying diodes, then the number of semiconductor devices is reduced, but EMI noise increases due to parasitic capacitance

Engineering Contradiction:

Improvenumber of semiconductor devicesVSAvoidEMI noise

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the parasitic capacitance parameter by replacing diodes with transistor switches. The transistor configuration reduces the total parasitic capacitance in the current path, thereby reducing EMI noise while maintaining a simplified device structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The substitution of rectifying diodes with transistor switches fundamentally changes the electrical characteristics of the circuit, reducing parasitic capacitance effects and associated EMI noise while keeping the bridgeless topology

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If switching frequency is reduced to lower EMI noise, then EMI performance improves, but the size of passive components increases and cost increases

Engineering Contradiction:

ImproveEMI noiseVSAvoidsize of passive components

Core Design Contradiction:

Object-generated harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent changes the resistance parameter of the switching elements to lower values, enabling effective EMI reduction without reducing switching frequency. This allows maintaining high switching frequencies with smaller passive components while achieving low EMI noise through improved semiconductor device characteristics

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed design significantly reduces conduction losses and improves EMI noise performance, achieving higher efficiency and reliability compared to conventional bridgeless PFC boost converters by lowering the number of semiconductor devices and utilizing transistor switches to minimize on-state resistance.

Implementation Method 1

reduces conduction losses and improves EMI noise performance, achieving higher efficiency and reliability compared to conventional bridgeless PFC boost converters by lowering the number of semiconductor devices and utilizing transistor switches to minimize on-state resistance

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9899910B2Bridgeless PFC power converter with reduced EMI noise

Publication Date: 2018.02.20 FLEXTRONICS AP LLC

AI summary

A bridgeless PFC boost converter has either a single switching cell or two identical switching cells configured to operate 180 degrees out of phase. A switching cell includes first and second transistor switches coupled to opposing ends of an input AC voltage source, and first and second rectifying diodes, one rectifying diode coupled in series to each of the two transistor switches. A boost inductor is coupled to a junction node between each transistor switch and rectifying diode series. Either a third rectifying diode or a third transistor switch is coupled to a junction node between the input AC voltage source and the first transistor switch. Either a fourth rectifying diode or a fourth transistor switch is coupled to a junction node between the input AC voltage source and the second transistor switch. The rectifying diodes are coupled an output capacitor. Two switching cells can be interleaved.