Multi-Color LED Drive Control Against Power Converter Saturation

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Solution Overview

Problem

Existing illumination devices using LEDs face issues with over-power or over-current conditions in their power converters due to changes in brightness and chromaticity settings, which can lead to transformer core saturation and failure, particularly in multi-colored LED devices with dimming and color tuning capabilities.

Innovation Solution

Incorporating a control circuit and temperature sensor to determine the maximum safe current and power levels of the power converters, adjusting drive currents to LED chains to prevent exceeding these limits, and using interpolation techniques to calculate lumens values that can be safely produced without causing over-current or over-power conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If drive currents to LED chains are increased to achieve desired brightness and chromaticity settings, then illumination performance is improved, but power converter over-current or over-power conditions occur leading to transformer core saturation and failure

Engineering Contradiction:

Improvebrightness and chromaticityVSAvoidpower converter saturation and failure

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The control circuit calculates and determines the maximum safe current and power levels before applying them to the power converters. By performing this calculation in advance based on temperature and LED chain characteristics, the system prevents over-current and over-power conditions before they can cause transformer core saturation or failure, while still allowing high illumination output when safe.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit continuously monitors temperature and adjusts the maximum safe current and power levels accordingly. This feedback mechanism ensures that as temperature increases, the safe operating limits are reduced to prevent overheating and saturation, while maintaining optimal illumination performance within the safe operating envelope.

Inventive Principle:

Principle #23Feedback

2Illumination intensity

If maximum safe current and power levels of power converters are increased to handle higher illumination demands, then illumination intensity is improved, but transformer core saturation and failure risks increase

Engineering Contradiction:

Improveillumination outputVSAvoidtransformer core saturation

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The maximum safe current and power levels are not fixed but dynamically adjusted based on real-time temperature measurements and LED chain characteristics. The control circuit continuously updates these limits to match actual operating conditions, allowing the system to safely operate at high illumination levels when temperature is low while automatically reducing limits as temperature increases to prevent transformer core saturation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operating parameters (current and power limits) of the power converters based on temperature and LED chain characteristics. By adjusting these parameters dynamically rather than using fixed maximum values, the system optimizes illumination output while maintaining safety margins that prevent transformer core saturation under varying operating conditions.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If drive currents are adjusted to prevent over-power or over-current conditions, then power converter reliability is improved, but illumination output may be reduced

Engineering Contradiction:

Improvepower converter safetyVSAvoidlumens output

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The control circuit performs preliminary calculations to determine the maximum safe current and power levels before adjusting drive currents. By pre-calculating these safe limits based on temperature and LED characteristics, the system ensures that illumination output is maximized within the safe operating envelope, preventing both over-power/over-current conditions and unnecessary reduction in illumination performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes drive current parameters to match the calculated maximum safe levels. Rather than using conservative fixed limits, the system adjusts parameters in real-time to optimize illumination output while maintaining safety margins, ensuring that lumens output is maximized without causing power converter saturation or failure.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUSRE50612E1Illumination device and method for avoiding an over-power or over-current condition in a power converter

Publication Date: 2025.09.30 LUTRON TECHNOLOGY COMPANY LLC

AI summary

An illumination device and methods are provided herein for avoiding over-current and over-power conditions in one or more power converters included within the illumination device. The illumination device may include at least a plurality of light emitting diode (LED) chains, a driver circuit, at least one power converter, and a control circuit. In some embodiments, the control circuit may be generally configured for determining a maximum safe current level and/or a maximum safe power level attributed to the power converter(s) at a present operating temperature, and for adjusting respective drive currents supplied to the plurality of LED chains by the driver circuit, so as not to exceed the maximum safe current level or the maximum safe power level at the present operating temperature. In some embodiments, a temperature sensor may be included within the illumination device for measuring the operating temperature presently associated with the power converter(s).