LED Lighting Circuit Buffer Components Surge Protection

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Solution Overview

Problem

Existing LED lighting circuits face issues with current spikes, electromagnetic interference (EMI), total harmonic distortion (THD), and surge protection, particularly in tapped linear drivers, which affect efficiency and reliability.

Innovation Solution

The introduction of buffer components connected across series strings of LED segments and current source circuits to clamp voltage, prevent power loss, and provide robust surge protection, along with capacitors and diodes to stabilize voltage and reduce flicker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If buffer components are connected across LED segments to clamp voltage and prevent current spikes, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesurge protectionVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A buffer component (capacitor) is introduced as an intermediary element connected across the LED segments. This capacitor clamps voltage spikes and prevents current surges from damaging the LEDs, thereby improving reliability without requiring fundamental changes to the circuit topology

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The buffer capacitor is positioned in advance across the LED segments to provide protective cushioning against voltage spikes and current surges before they can damage the LEDs. This preemptive protection mechanism enhances reliability by preventing surge damage before it occurs

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Use of energy by moving object

If buffer components are added to stabilize voltage across LED segments, then efficiency is improved, but device complexity increases

Engineering Contradiction:

ImproveefficiencyVSAvoidcircuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The buffer capacitor acts as an intermediary energy storage element that stabilizes voltage across LED segments during switching transitions. This voltage stabilization improves efficiency by preventing energy loss from voltage fluctuations and current spikes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The buffer component changes the voltage parameter stability across the LED segments by providing capacitive coupling. This stabilizes the operating point and improves efficiency by reducing power loss during dynamic operation

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If switches are used to bypass LED segments in a tapped linear driver, then adaptability is improved, but harmful factors increase due to current spikes and EMI

Engineering Contradiction:

Improvevoltage matchingVSAvoidcurrent spikes

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The buffer capacitor serves as a mediator between the switching action and the LED segments. When switches bypass LED segments to match forward voltage with input voltage, the capacitor absorbs the resulting current spikes and voltage transients, preventing harmful EMI while maintaining the adaptability of the tapped linear driver topology

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances efficiency by 5%, improves EMI margin to 20dB, reduces THD to 3%, and mitigates surge risks by effectively managing current spikes and voltage stability, resulting in a more reliable LED lighting circuit.

Implementation Method 1

said buffer component comprises a capacitor, said capacitor is adapted to buffer a voltage across the at least two LED segments when the switches of the at least two LED segment are open, and discharge via one switch of one LED segment and the other LED segment when the switch of the one LED segment closes while the switch of the other LED segment is still open

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

A discharge of the buffer component still flows through on LED segment to prevent power loss. Preferably, the buffer component also clamps the voltage of a current source circuit

Methodology Applied

Scientific EffectVoltage clamping:

Implementation Method 3

It can also mitigate surge risk to the LED and to the current source, since the buffer component can also shunt the surge current to the ground (another polarity of the input)

Methodology Applied

Scientific EffectSurge protection:

Data Source

PatentEP3850910B1A LED lighting circuit and a lighting device comprising the same

Publication Date: 2022.11.09 SIGNIFY HOLDING BV

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AI summary

In order to reduce energy loss of a tapped linear driver, it is proposed an LED lighting circuit, comprising an input (Vbus, GND) adapted to receive an input voltage, a plurality of LED segments (LED1, LED2, LED3, LED) connected in series and to the input, a buffer component (C9) connected to an anode and a cathode of a series string of at least two of the plurality of LED segments with respective switches, a current source circuit (B1) in series connection with a parallel connection of the buffer component (C9) and the at least two LED segments, across the input; further comprising a further buffer component (C5) across the current source circuit (B1), wherein said buffer component (C9) and the further buffer component (C5) is in series connection.