Adaptive Bleeder Circuit for TRIAC Dimmer Stability
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Solution Overview
Problem
Existing LED lamp control circuits with TRIAC dimmers face issues of high power consumption and low efficiency due to surge currents and flickering, as the bleeder circuit in prior art solutions generates additional power consumption and inefficiencies.
Innovation Solution
A bleeder circuit with a control method that detects the cross-zero point of the input voltage, delays the bleeder current generation, and adjusts the delay time based on the time it takes for the input current to reach a predetermined value, optimizing the bleeder current duration to minimize power consumption and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bleeder circuit generates bleeder current continuously to maintain TRIAC dimmer input current above maintaining current, then the TRIAC dimmer operates stably without flickering, but the power consumption increases and conversion efficiency decreases
Solution Approach 1:
The bleeder circuit operates periodically rather than continuously. The control circuit detects the input voltage waveform, identifies zero-crossing points, and activates the bleeder module only during specific intervals when the LED driving circuit current is insufficient to maintain TRIAC operation. This periodic activation maintains TRIAC stability while minimizing power consumption.
Solution Approach 2:
The system uses its own input voltage waveform and current feedback to automatically control the bleeder circuit operation. The control circuit monitors the input voltage zero-crossing points and the LED driving circuit current, and autonomously decides when to activate the bleeder module, eliminating the need for external control signals or continuous power supply to the bleeder circuit.
2Reliability
If the bleeder circuit is activated early after TRIAC turn-on to ensure maintaining current, then the TRIAC dimmer operates reliably, but the bleeder current duration increases and power consumption increases
Solution Approach 1:
The control circuit uses feedback from the LED driving circuit current to determine when to activate the bleeder module. By monitoring the actual current level and comparing it with the maintaining current threshold, the system activates the bleeder circuit only when necessary, precisely controlling the activation timing based on real-time current conditions rather than fixed timing.
Solution Approach 2:
The control circuit detects zero-crossing points of the input voltage in advance and uses this information to predict when the LED driving circuit current may become insufficient. By preparing to activate the bleeder module at the appropriate moment after zero-crossing detection, the system ensures timely current supplementation without premature activation that would extend bleeder current duration unnecessarily.
Data Source
AI summary
The present disclosure discloses a bleeder circuit and a control method thereof, and an LED control circuit. The present disclosure is applied in an LED control circuit of TRIAC dimming, directly or indirectly detects cross-zero point of input voltage; after cross-zero point of the input voltage is delayed by a second time, the bleeder module works to generate bleeder current, and a time between turn-on time of the TRIAC and a time that a driving circuit input current achieves a predetermined value (maintaining current of TRIAC) is a first time. During the first time, the bleeder circuit generates losses; when the first time is greater than a predetermined value, the second time is prolonged; when the first time is smaller than the predetermined value, the second time is reduced, such that the first time is close to or equal to the predetermined value. By using the present disclosure, the second time, which is used as the delay time, is self-adaptively adjusted according to the first time and the predetermined value, and the bleeder power consumption is reduced and system efficiency is enhanced.