LED Load Control Turn-On Using Learned Voltage Charging
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Solution Overview
Problem
Existing LED light sources face challenges in achieving consistent and fast turn-on times across lighting loads with different voltage ratings, particularly when using current or voltage load control techniques.
Innovation Solution
A load control device with a power converter circuit and control circuit that learns the load voltage and adjusts the power converter operation to ensure rapid and consistent turn-on times by using open-loop control during capacitor charging and closed-loop control once the voltage reaches a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage load control technique is used with multiple parallel strings of LEDs, then the voltage across the LED light source can be regulated to ensure proper operation, but the turn-on time becomes inconsistent across different lighting loads with different voltage ratings
Solution Approach 1:
The control circuit performs preliminary actions by detecting load characteristics (voltage rating) during a learning phase before normal operation. This preliminary detection allows the system to pre-configure appropriate control parameters, ensuring both proper operation and consistent turn-on time across different LED loads without requiring manual configuration.
Solution Approach 2:
The control circuit dynamically adapts its operation based on detected load characteristics. By monitoring parameters such as voltage across the LED light source and adjusting control strategies accordingly, the system maintains reliable operation while achieving consistent turn-on performance across diverse voltage ratings. The system transitions from a static control approach to a dynamic one that responds to actual load conditions.
2Illumination intensity
If a current load control technique is used, then the current through the LED light source can be regulated to ensure appropriate intensity and color, but the turn-on time varies across lighting loads with different voltage ratings
Solution Approach 1:
The control circuit implements feedback mechanisms by continuously monitoring load characteristics during operation. By detecting parameters such as voltage across the LED light source and using this information to adjust control parameters, the system maintains consistent turn-on time while preserving proper current regulation for light intensity and color. The feedback loop enables real-time adaptation to different voltage ratings.
Solution Approach 2:
The system changes control parameters based on detected load characteristics. By identifying the voltage rating of different LED loads and adjusting current control parameters accordingly, the system achieves consistent turn-on performance across various voltage ratings while maintaining appropriate light intensity and color. This involves modifying operational parameters such as current limits, ramp rates, or duty cycles based on the learned load profile.
3Reliability
If different control techniques are used for different voltage ratings, then proper operation can be ensured, but the device complexity increases
Solution Approach 1:
The control circuit performs self-service by automatically detecting and learning load characteristics without external intervention. The system autonomously identifies voltage ratings and configures appropriate control parameters through an embedded learning phase, eliminating the need for manual configuration or complex switching between different control modes. This self-configuration capability maintains reliability across different voltage ratings while keeping the device complexity manageable.
Solution Approach 2:
The control circuit is designed with multi-functionality to handle various voltage ratings using a single unified control architecture. By incorporating universal detection and adaptation capabilities, the system can properly operate with different LED load voltage ratings without requiring separate dedicated circuits for each voltage level. The universal design approach reduces overall device complexity compared to having multiple specialized control paths.
Data Source
AI summary
A load control device may be configured to turn on lighting loads to obtain a fast turn-on time that may be substantially consistent across lighting loads that have different load voltages. The load control device may comprise a power converter circuit configured to produce a voltage across a capacitor, and a control circuit configured to control the power converter circuit to generate the voltage across the capacitor. The control circuit may determine a learned voltage from the magnitude of the voltage across the capacitor. For example, the control circuit may measure the magnitude of the voltage and store the measured voltage as the learned voltage. The control circuit may determine an operating parameter for the power converter circuit as a function of the learned voltage, and control the power converter circuit according to the operating parameter to charge the capacitor until the magnitude of the voltage exceeds a threshold.