LED Drive Circuit SCR Dimmer Dynamic Bleeding Current Control
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Solution Overview
Problem
Existing LED drive circuits with SCR dimmers suffer from inefficiency due to high bleed loss, as they typically operate at constant bleeding currents greater than the latching and holding currents of the SCR dimmer, leading to excessive energy loss and reduced efficiency.
Innovation Solution
An LED drive circuit with a bleeder circuit and controller that dynamically adjusts bleeding currents based on detected voltage changes, switching between first, second, and third currents (equal to or greater than latching, holding, and less than holding currents of the SCR dimmer) to minimize bleed loss and optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant bleeding current is used in LED drive circuit with SCR dimmer, then the SCR dimmer can be reliably turned on and maintained, but bleed loss increases and efficiency decreases
Solution Approach 1:
The patent applies dynamics by transitioning from constant bleeding current to dynamic multi-level bleeding current. The controller switches between first, second, and third current levels based on real-time detection of direct current bus voltage, enabling the bleeding current to adapt to different operational states and minimize energy loss while ensuring reliable SCR dimmer operation.
Solution Approach 2:
The patent changes the parameter of bleeding current from a fixed value to a variable parameter with multiple discrete levels. By detecting voltage jumps and comparing against reference voltages, the system dynamically adjusts the bleeding current parameter between at least three different current levels, optimizing both reliability and energy efficiency.
2Reliability
If high bleeding current is used to ensure SCR dimmer operation, then the SCR dimmer can be reliably triggered, but energy efficiency is reduced
Solution Approach 1:
The patent applies partial action by using different current levels for different operational requirements. The first current level provides sufficient current for reliable SCR triggering and maintenance, while the second and third current levels use reduced current when full triggering current is not needed, thereby optimizing energy efficiency while maintaining operational reliability.
3Loss of energy
If bleeding current is reduced to improve efficiency, then energy loss is reduced, but SCR dimmer may fail to turn on or maintain operation
Solution Approach 1:
The patent implements feedback by continuously detecting the direct current bus voltage and using this information to dynamically adjust the bleeding current level. The controller compares the detected voltage with reference voltages and switches between current levels accordingly, ensuring that sufficient current is provided for reliable SCR operation while minimizing energy loss during normal operation.
Data Source
AI summary
An LED drive circuit with a SCR dimmer, a circuit module and a control method therefor are provided. In each cycle of the alternating current, the bleeding current during a time period for turning on the SCR dimmer is distinguished from the bleeding current in a time period from an instant at which the SCR dimmer is turned on to an instant at which the LED load is lit. The bleeder circuit is controlled to perform bleeding at the first current during the time period for turning on the SCR dimmer, and then perform bleeding at the second current which is less than the first current from the instant at which the SCR dimmer is turned on, so that an average bleeding current of the bleeder circuit in each cycle can be reduced, the bleed loss can be reduced, and the efficiency of the LED drive circuit can be improved.