LED Control Circuit for Dimmer Compatibility and High Power Factor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Linear LED driving circuits have low power factors, leading to harmonic pollution and incompatibility with dimmers, reducing the quality of the power grid and causing interference with other electrical equipment.
Innovation Solution
A control circuit and method for a lighting circuit that detects the presence of a dimmer and adjusts the operation of light strings connected in series, using a voltage detecting circuit and current control circuit with MOS transistors and sampling resistors to manage power factor and compatibility, ensuring simultaneous or individual string activation based on rectified voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a linear LED driving circuit is used, then the implementation is simple and cost is low, but the power factor is low causing harmonic pollution and incompatibility with dimmers
Solution Approach 1:
The LED load is divided into multiple parallel light strings (first light string, second light string, etc.), each controlled by independent switch modules. This segmentation allows the circuit to selectively activate specific strings based on voltage detection, enabling power factor correction while maintaining simple linear driving topology for each string.
Solution Approach 2:
The voltage detecting circuit performs preliminary detection of the rectified voltage before the LED strings are activated. Based on this preliminary detection, the control circuit determines which light strings should be turned on to achieve the desired power factor, preventing harmonic pollution before it occurs.
2Use of energy by moving object
If the linear LED driving circuit operates in constant current conduction mode, then the LED is driven efficiently, but the power factor remains low and compatibility with dimmers is poor
Solution Approach 1:
The circuit dynamically adjusts its operation based on voltage detection. The control circuit switches between different conduction modes: constant current mode for normal operation and selective string activation mode for power factor correction. This dynamic adaptation enables both efficient LED conduction and dimmer compatibility.
Solution Approach 2:
The circuit changes operational parameters based on detected voltage levels. When the rectified voltage falls within specific voltage ranges, the control circuit activates corresponding light strings with different current characteristics, thereby changing the overall electrical parameters to achieve high power factor and dimmer compatibility while maintaining LED efficiency.
3Object-generated harmful factors
If multiple light strings are activated simultaneously, then the total current increases improving power factor, but the control complexity increases
Solution Approach 1:
The control circuit is segmented into independent voltage detecting circuit and current control circuit, each with dedicated functions. The voltage detecting circuit independently monitors voltage levels, while the current control circuit independently controls switch modules based on detection results. This functional segmentation simplifies the overall control logic despite managing multiple light strings.
Solution Approach 2:
The voltage detecting circuit serves multiple functions: it detects the rectified voltage level, determines which light strings should be activated, and provides control signals to the current control circuit. This multi-functionality reduces the need for separate detection and control components, simplifying the overall control system while managing multiple light strings.
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
The solution achieves a high power factor and compatibility with dimmers, reducing harmonic pollution and improving grid quality, while being simple to implement.
Implementation Method 1
The high potential end of the rectified voltage is connected to a first end of the first light string through a first unilateral conduction element
Data Source
AI summary
Disclosed a control circuit for a lighting circuit. In the control circuit, an AC input signal provided at an AC input terminal is rectified to obtain a rectified voltage, a low potential end of the rectified voltage is used as a reference ground, a load of the lighting circuit is composed of N strings connected in series, and N is a natural number greater than or equal to 2, when the control circuit detects that the AC input terminal is connected to a dimmer, the control circuit controls the N strings to be simultaneously turned on, when the control circuit detects that the AC input terminal is not connected to the dimmer, the control circuit controls the N strings to be individually turned on in accordance with the rectified voltage. According to the present disclosure, the lighting circuit can obtain a high power factor and is compatible with the dimmer, and the scheme is simple and easy to implement.