BJT Dynamic Mode Control for LED Dimmer Compatibility

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Solution Overview

Problem

Conventional LED lamp systems with phase-cut dimmer switches face challenges in properly functioning internal circuitry due to the need for multiple current control paths, leading to power losses and inefficiencies, especially when using TRIAC circuits.

Innovation Solution

A switching power converter dynamically controls operation between switching and linear modes using a bipolar junction transistor (BJT) to function as a switch or current sink, allowing proper functioning of the dimmer switch internal circuitry and minimizing power losses by discharging capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional LED lamps use multiple current control paths to draw current from the dimmer switch, then the internal circuitry of the dimmer can function properly, but power losses increase and efficiency decreases

Engineering Contradiction:

Improvedimmer internal circuitry functionalityVSAvoidpower losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the BJT operating mode changeable based on system conditions. The BJT can operate in switching mode (cutoff/saturation) for efficient power conversion or in linear mode (active region) to draw current from the dimmer and discharge capacitors. This dynamic adaptation allows the system to optimize between efficiency and dimmer compatibility, resolving the contradiction between power losses and dimmer functionality.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If the BJT operates in switching mode to provide efficient DC output voltage, then power conversion efficiency is improved, but the dimmer switch internal circuitry cannot function properly due to insufficient current draw

Engineering Contradiction:

Improvepower lossesVSAvoiddimmer internal circuitry functionality

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements periodic action by alternating between switching mode operation (for efficiency) and linear mode operation (for dimmer compatibility). The controller dynamically switches between these modes based on whether current draw from the dimmer is needed to maintain its internal circuitry functionality. This periodic alternation allows the system to achieve both low power losses and proper dimmer operation.

Inventive Principle:

Principle #19Periodic action

3Reliability

If the BJT operates in linear mode to draw current from the dimmer switch, then the dimmer internal circuitry functions properly and capacitors are discharged, but power losses increase

Engineering Contradiction:

Improvedimmer internal circuitry functionalityVSAvoidpower losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If conventional LED lamps are designed to operate with phase-cut dimmer switches using TRIAC circuits, then compatibility with existing dimmer switches is achieved, but multiple current control paths are required leading to increased device complexity

Engineering Contradiction:

Improvedimmer switch compatibilityVSAvoidcurrent control paths

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by making the BJT serve multiple functions through different operating modes. The same BJT component can perform switching functions (for efficient power conversion) and linear current sinking functions (for dimmer compatibility and capacitor discharge). This multi-functionality eliminates the need for separate current control paths, reducing device complexity while maintaining dimmer switch compatibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8716948B2Dynamic control of power switching bipolar junction transistor

Publication Date: 2014.05.06 DIALOG SEMICONDUCTOR INC

AI summary

The embodiments disclosed herein describe the dynamic control of a switching power converter between different operation modes of the switching power converter. In one embodiment, the operation modes of the switching power converter include a switching mode and a linear mode. The switching power converter may be included in a LED lamp system according to one embodiment.