Constant Current Regulator for Airfield Lighting

Solution Overview

Problem

Conventional constant current regulators for airfield ground lighting are bulky due to large transformers operating at 50 Hz, which are sensitive to harmonics and perform poorly under DC offset imbalance, necessitating a more compact and efficient solution.

Innovation Solution

A constant current regulator design utilizing a transformer at a higher operating frequency, incorporating bi-directional switches, a rectifier, and an inverter with a controller for pulse width modulation to ensure input voltage and current are in phase, reducing transformer size and weight while providing galvanic isolation and a pure sinusoidal output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transformer operating at 50 Hz is used in conventional constant current regulators, then isolation between AC mains and airfield runway lamps is provided, but the transformer becomes large and heavy, resulting in a large unit footprint

Engineering Contradiction:

Improveisolation between AC mains and airfield runway lampsVSAvoidtransformer weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent changes the operating frequency parameter from conventional 50 Hz to a higher frequency (e.g., 400 Hz or higher). This parameter change allows the transformer to achieve the same isolation function with significantly reduced size and weight, as transformer dimensions are inversely proportional to operating frequency for a given power level

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a transformer operating at 50 Hz is used in conventional constant current regulators, then isolation between AC mains and airfield runway lamps is provided, but the transformer becomes large and heavy, resulting in a large unit footprint

Engineering Contradiction:

Improveisolation between AC mains and airfield runway lampsVSAvoidunit footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the operating frequency parameter from conventional 50 Hz to a higher frequency (e.g., 400 Hz or higher). This parameter change allows the transformer to achieve the same isolation function with significantly reduced size and weight, as transformer dimensions are inversely proportional to operating frequency for a given power level

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a conventional transformer design is used, then isolation is provided, but the regulator is sensitive to harmonics and performs poorly under DC offset imbalance

Engineering Contradiction:

Improveisolation functionVSAvoidperformance under harmonics and DC offset imbalance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the operating frequency to a higher value (e.g., 400 Hz or higher), which improves the transformer's frequency response characteristics and reduces sensitivity to harmonics. The higher operating frequency allows for better performance under non-ideal conditions including DC offset imbalance and harmonic distortion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent incorporates bi-directional switches that enable dynamic control of the transformer operation. This dynamic capability allows the system to adapt to varying load conditions, harmonics, and DC offset scenarios, improving overall adaptability while maintaining isolation functionality

Inventive Principle:

Principle #15Dynamics

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 results in a compact, modular, and efficient constant current regulator with fast dynamic load response and improved harmonic resistance, enabling smaller and lighter transformers while maintaining isolation and compliance with regulatory standards.

Implementation Method 1

a transformer configured to isolate the AC signal from an airfield ground lighting circuit

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a rectifier configured to convert the signal from the AC mains from AC to direct current (DC)

Methodology Applied

Scientific EffectElectromagnetic rectification:

Implementation Method 3

an inverter configured to convert the DC signal from the power converter and convert the DC to AC

Methodology Applied

Scientific EffectElectromagnetic inversion:

Data Source

PatentUS9942964B2Constant current regulator for airfield ground lighting

Publication Date: 2018.04.10 HONEYWELL INTERNATIONAL INC

AI summary

A constant current regulator for airfield ground lighting is described herein. For example, one or more embodiments include a power converter configured to receive a signal from an alternating current (AC) mains, where the power converter includes a number of bi-directional switches, a transformer configured to isolate the AC signal from an airfield ground lighting circuit, and a rectifier configured to convert the signal from the AC mains from AC to direct current (DC), an inverter configured to convert the DC signal from the power converter and convert the DC to AC, an output filter configured to receive the AC signal from the inverter and send the AC signal to the airfield ground lighting circuit, and a controller configured to switch the number of bi-directional switches of the power converter to allow an input voltage and current of the signal from the AC mains to be in phase.