Bridgeless Boost PFC Circuit for Constant Current Input

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Solution Overview

Problem

Existing power factor correction techniques are designed for constant voltage systems and cannot be effectively applied to constant current systems, such as those used in airfield lighting, where consistent brightness across multiple light fixtures requires a constant current power source.

Innovation Solution

A bridgeless constant current power factor correction circuit that includes an input capacitor and two switching devices (MOSFETs) controlled by a controller, which switches between ON and OFF states to charge and drain the capacitor, producing an input voltage waveform in phase with the input current waveform, eliminating the need for a diode rectifier bridge and reducing power loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional voltage-based power factor correction circuitry is used, then power factor correction can be achieved in constant voltage systems, but it cannot be applied to constant current systems such as airfield lighting

Engineering Contradiction:

Improveapplicability to constant current systemsVSAvoidsystem performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent inverts the traditional voltage-based PFC approach by implementing a current-based PFC circuit. Instead of making input current match input voltage in constant voltage systems, the circuit is designed to make input voltage match input current in constant current systems. This is achieved by using current sources instead of voltage sources and configuring the switching circuitry to control voltage waveform rather than current waveform.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the fundamental operating parameters from voltage-based to current-based control. The circuit uses constant current sources as the primary power input and controls the voltage waveform to be sinusoidal and in-phase with the current waveform. This parameter transformation enables PFC functionality in constant current systems where traditional voltage-based approaches fail.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a diode rectifier bridge is used in traditional PFC circuits, then voltage rectification is achieved, but power loss increases and the circuit cannot function with constant current input

Engineering Contradiction:

Improvepower lossVSAvoidcompatibility with constant current sources

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent removes the diode rectifier bridge from the circuit configuration. Instead of using passive diode rectification, the design extracts only the essential function of waveform shaping and implements it through active switching devices (MOSFETs or IGBTs) controlled by gate signals. This elimination of the rectifier bridge reduces power loss and enables compatibility with constant current sources.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the passive mechanical/electrical diode rectifier system with an active electronic switching system. The switching devices are controlled by electronic gate signals to achieve voltage waveform shaping without the need for diode rectification. This substitution reduces power loss and provides adaptability to constant current input sources.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables efficient power factor correction in constant current systems by synchronizing the voltage waveform with the input current, improving energy efficiency and extending the life of the lighting system.

Implementation Method 1

an input capacitor configured to receive an input current from a constant current source and produce an input voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the first switching device is operable during a first half cycle of the input current and shorted during a second half cycle of the input current

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9190901B2Bridgeless boost power factor correction circuit for constant current input

Publication Date: 2015.11.17 EATON INTELLIGENT POWER LTD

AI summary

The present disclosure provides techniques for power factor correction on a constant current system without the use of a diode rectifier bridge. In an example embodiment, the present disclosure provides a power factor correction circuit which includes two switching MOSFETs biased in opposite directions which operate during opposite half cycles of the input current. The power factor correction circuit generates an input voltage to match the phase of the input current. The input voltage is generated via charging and draining of an input capacitor by the MOSFETs. The MOSFETs are driven on a duty cycle synchronously associated with the input current wave form.