AC LED Driving Circuit with VCCS for Stable Dimmer Operation
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Solution Overview
Problem
Conventional AC LED driving circuits face challenges in ensuring stable operation of dimmers when the current supplied is insufficient, leading to suboptimal dimmer performance, especially with advancements in LED efficiency reducing current requirements.
Innovation Solution
An AC LED driving circuit configuration where an LED driving circuit and a dimmer driving circuit are connected in parallel, utilizing a voltage-controlled current source and a common resistor to compensate for current deficiencies, ensuring stable dimmer operation without requiring separate control circuits for timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate control circuit is added to check the driving time point of ILED1 and turn off I_HOLD, then the dimmer can be stably driven, but the device complexity increases
Solution Approach 1:
The patent merges the LED driving circuit and dimmer driving circuit into a single integrated circuit structure. The voltage-controlled current source serves dual purposes: driving LEDs when sufficient current is available and providing hold current for the dimmer when LED current is insufficient. This elimination of separate control circuits resolves the contradiction by maintaining reliability through integrated design while reducing device complexity.
Solution Approach 2:
The voltage-controlled current source is designed with multi-functionality, serving both as an LED driver and a dimmer holder. It automatically adapts its operation based on the current conditions, providing LED driving current when available and dimmer hold current when needed. This universal component eliminates the need for separate control circuits, resolving the contradiction between reliability and complexity.
2Adaptability or versatility
If I_HOLD is set to a fixed current value independent of LED current sources, then the dimmer can be driven when AC power is decreased, but the dimmer cannot be normally operated when LED current is insufficient
Solution Approach 1:
The patent implements a dynamic current allocation system where the voltage-controlled current source automatically adjusts its output based on real-time current conditions. When LED current is sufficient, the circuit directs current to LEDs; when LED current becomes insufficient, the circuit dynamically switches to providing hold current for the dimmer. This dynamic adaptation ensures both versatility under varying AC power and reliable normal operation of the dimmer.
Solution Approach 2:
The circuit employs feedback mechanisms through the voltage-controlled current source that monitors current conditions and automatically adjusts its operation. The feedback loop ensures that when LED current drops below the threshold required for dimmer operation, the system responds by providing adequate hold current to maintain dimmer functionality. This feedback mechanism resolves the contradiction by ensuring reliable dimmer operation while maintaining adaptability.
3Use of energy by moving object
If LED optical efficiency increases beyond 160lm/W, then LED current requirements decrease, but the dimmer current requirement (20-40mA) cannot be met by LED current alone
Solution Approach 1:
The patent segments the current supply function into two distinct paths: one for LED driving and another for dimmer holding. The voltage-controlled current source is configured to provide separate current paths, allowing LED current to be optimized for high efficiency while independently ensuring sufficient current (20-40mA) is available for the dimmer. This segmentation resolves the contradiction by decoupling LED efficiency optimization from dimmer current requirements.
Solution Approach 2:
The voltage-controlled current source acts as an intermediary between the power supply and the dimmer, ensuring that sufficient current is always available for dimmer operation regardless of LED current requirements. This intermediary component mediates the conflict between high LED efficiency (lower current demand) and dimmer operation (minimum current requirement), resolving the contradiction by guaranteeing adequate current supply to the dimmer while allowing LED efficiency to be optimized.
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 configuration ensures the dimmer is always operated normally by compensating current shortfalls with hold current values, maintaining optimal performance across varying LED current conditions.
Implementation Method 1
an output voltage of the voltage-controlled current source connected in series with the common resistor is input as a negative (−) voltage to the voltage-controlled current source, and then the current supplied from the rectification circuit to the LED driving unit is included in a negative feedback path of the dimmer driving unit
Data Source
AI summary
Disclosed herein is an AC LED driving circuit. The AC LED driving circuit includes a power supply unit. An LED driving unit includes an LED lighting unit having a first LED unit to an n-th LED unit, and a plurality of switching circuit units. A dimmer driving unit includes a VCCS, an input terminal and an output terminal of which are respectively connected to a connection line between the output terminal of the rectification circuit and the first LED unit and to an output terminal of the switching circuit units, a reference voltage supply unit, and a common resistor, a first end of which is connected to a negative terminal of the reference voltage supply unit, and a second end of which is connected in common to an output line of the VCCS and to an output terminal of the switching circuit units.