Dual-Path Power Factor Correction Circuit for Zero Voltage Switching

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Solution Overview

Problem

Existing semi-resonant power factor correction circuits face issues with high switching losses and overvoltages due to resonant inductance and capacitance, leading to potential damage to semiconductor switches and inductances, and require additional components for overvoltage limiting which increases energy losses.

Innovation Solution

The implementation of a circuit with a first switching path that can turn off and on in both directions, combined with a second switching path featuring two electronic switches and capacitance, allowing for zero voltage switching (ZVS) and efficient commutation without additional components, using a capacitance and diode path to manage switch currents and avoid overvoltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If resonant inductance and capacitance are used in semi-resonant PFC circuits, then power factor correction is achieved, but high switching losses and overvoltages occur

Engineering Contradiction:

Improveswitching lossesVSAvoidsemiconductor switch damage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The circuit is divided into two independent switching paths: a first switching path with at least one electronic switch, and a second switching path with two electronic switches and capacitance. This segmentation allows each path to be optimized independently, with the second path providing a safe commutation route that prevents overvoltages and reduces switching losses in the first path.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second switching path acts as an intermediary commutation path that mediates the switching transitions. When switches in the first path need to commutate, current can flow through the second path with its capacitance and diode paths, preventing direct overvoltage stress on the primary switches and enabling softer switching transitions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If additional components are added for overvoltage limiting, then component protection is improved, but energy losses increase

Engineering Contradiction:

Improvecomponent protectionVSAvoidenergy losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The circuit uses inherent diodes (body diodes) of the MOSFET semiconductor switches to provide the necessary commutation paths, eliminating the need for external protection diodes. The capacitance in the second switching path naturally limits overvoltages during commutation without requiring additional energy-dissipating components, as the system uses its own existing components for protection.

Inventive Principle:

Principle #25Self-service

3Reliability

If a low inductance commutation path is provided, then overvoltages are avoided, but switching losses may increase

Engineering Contradiction:

Improveovervoltage avoidanceVSAvoidswitching losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention changes the inductance parameter of the commutation path by providing a low inductance path through the second switching path's capacitance and diode connections. This low inductance commutation path allows current to transition quickly between switches without generating significant back-EMF or overvoltages, while the controlled nature of the switching maintains efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention converts the potentially harmful effect of low inductance (which can cause rapid current changes and ringing) into a benefit by using it specifically for commutation. The low inductance path enables fast, clean current transfer during switching transitions, reducing the duration of switching losses while the capacitance provides voltage clamping to prevent overvoltages.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach reduces unnecessary switching losses and avoids undesirable overvoltages, enabling efficient operation with DC isolated converters and achieving zero voltage switching, thus protecting components and improving energy efficiency.

Implementation Method 1

enabling efficient operation with DC isolated converters and achieving zero voltage switching

Methodology Applied

Scientific EffectZero voltage switching (ZVS):

Implementation Method 2

a second switching path comprising two electronic switches and at least one capacitance

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10819222B2Circuitry for power factor correction and methods of operation

Publication Date: 2020.10.27 INFINEON TECH AUSTRIA AG

AI summary

A circuit is proposed comprising (i) a first switching path comprising at least one electronic switch, wherein the first switching path can turn off in both directions and can turn on in both directions, and (ii) a second switching path comprising two electronic switches and at least one capacitance, wherein one diode path per electronic switch is embodied in parallel with the electronic switch or in series with the electronic switch. Additionally, a method for operating such a circuit is specified.