Bridgeless Boost PFC Demagnetization Detection

Solution Overview

Problem

Conventional demagnetization-sensing circuits for bridgeless PFC converters are inefficient due to the use of sense resistors, which are dissipative and unusable in high-efficiency applications, especially at high voltages, as they can only detect a single polarity of demagnetization pulses.

Innovation Solution

A bridgeless PFC converter design that eliminates the sense resistor by using auxiliary windings inductively coupled to the boost inductor and a voltage comparator to detect magnetization states, allowing for efficient demagnetization sensing across both positive and negative polarities without dissipative elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sense resistors are used for demagnetization sensing in bridgeless PFC converters, then the polarity of demagnetization pulses can be detected, but energy loss increases due to the dissipative nature of resistors

Engineering Contradiction:

Improvedemagnetization pulse polarity detectionVSAvoidenergy loss

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent replaces the resistive sensing mechanism with an inductive sensing mechanism using an auxiliary winding. Instead of using a sense resistor that dissipates energy as heat, the invention uses an auxiliary winding inductively coupled to the boost inductor to sense the demagnetization pulses. This substitution of the sensing mechanism eliminates the energy loss associated with resistive elements while maintaining the ability to detect demagnetization events.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an auxiliary winding as an intermediary element between the boost inductor and the sensing circuit. This auxiliary winding is inductively coupled to the boost inductor and provides a non-dissipative path for sensing the demagnetization pulses. The intermediary winding transfers the magnetic flux information from the boost inductor to the sensing circuit without the energy loss inherent in direct resistive sensing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If sense resistors are used for demagnetization sensing, then the circuit can operate at high voltages, but efficiency decreases due to dissipative losses

Engineering Contradiction:

Improvehigh voltage operation capabilityVSAvoidconversion efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the resistive sensing mechanism with an inductive sensing mechanism using an auxiliary winding. Instead of using a sense resistor that dissipates energy as heat, the invention uses an auxiliary winding inductively coupled to the boost inductor to sense the demagnetization pulses. This substitution of the sensing mechanism eliminates the energy loss associated with resistive elements while maintaining the ability to detect demagnetization events.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If conventional demagnetization-sensing circuits are used in bridgeless PFC converters, then the circuit structure is simple, but the converter efficiency is reduced due to dissipative elements

Engineering Contradiction:

Improvecircuit structureVSAvoidconverter efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent replaces the resistive sensing mechanism with an inductive sensing mechanism using an auxiliary winding. Instead of using a sense resistor that dissipates energy as heat, the invention uses an auxiliary winding inductively coupled to the boost inductor to sense the demagnetization pulses. This substitution of the sensing mechanism eliminates the energy loss associated with resistive elements while maintaining the ability to detect demagnetization events.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The auxiliary winding serves multiple functions: it provides demagnetization sensing, it enables polarity detection, and it does so without the energy losses associated with resistive sensing. By making the auxiliary winding multi-functional, the patent achieves improved efficiency without significantly increasing circuit complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This design enhances the efficiency of bridgeless PFC converters by enabling effective demagnetization sensing without dissipative elements, allowing them to operate efficiently even at high voltages and high-efficiency applications.

Implementation Method 1

auxiliary windings inductively coupled to the boost inductor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9742264B2Boost inductor demagnetization detection for bridgeless boost PFC converter operating in boundary-conduction mode

Publication Date: 2017.08.22 MURATA MFG CO LTD

AI summary

A bridgeless converter includes a boost inductor connected in series with an alternating-current power source, a first series circuit including a first switching device and a second switching device connected in series with each other, a second series circuit including a third switching device and a fourth switching device connected in series with each other, a capacitor connected in parallel with the first series circuit and the second series circuit, and a magnetization sensing circuit including at least one auxiliary winding inductively coupled to the boost inductor.