Electronic Ballast Bleeder Circuit Dynamic Control
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Solution Overview
Problem
Existing LED lighting systems with electronic ballasts face inefficiencies and electromagnetic interference due to the unnecessary operation of bleeder circuits when connected to non-dimmable mains, as they require a low ohmic load to function correctly with dimmer circuits.
Innovation Solution
A method to control the electronic ballast by determining the presence of a dimmer circuit within a few mains cycles and adjusting the bleeder current accordingly, using parameters such as time intervals, voltage thresholds, and voltage differentials to minimize bleeder losses and adapt to different types of dimmers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder circuit is provided in the LED driver to ensure compatibility with dimmer circuits, then the dimmer circuit operates correctly, but energy efficiency drops by up to 10% and electromagnetic interference increases when the bleeder operates unnecessarily on non-dimmable mains
Solution Approach 1:
The bleeder circuit is made dynamically controllable through a switching element that adjusts its operation based on real-time detection of dimmer presence. The system transitions from a static always-on bleeder to a dynamic system that activates or deactivates the bleeder based on whether a dimmer is detected, thereby eliminating unnecessary energy losses while maintaining dimmer compatibility when needed
Solution Approach 2:
The system implements feedback by continuously monitoring the mains voltage characteristics to detect the presence of a dimmer circuit. Based on this feedback information, the control circuit adjusts the bleeder switching element accordingly - keeping the bleeder active when a dimmer is detected and deactivating it when no dimmer is present, thus optimizing energy efficiency while ensuring proper dimmer operation when required
2Reliability
If a bleeder circuit is provided to ensure compatibility with dimmer circuits, then the dimmer circuit operates correctly, but electromagnetic interference problems increase when the bleeder is dynamically controlled
Solution Approach 1:
The system performs preliminary detection of dimmer presence during the mains voltage cycle before making switching decisions. By detecting the dimmer characteristics in advance and planning the bleeder activation accordingly, the system minimizes sudden switching transients and reduces electromagnetic interference while ensuring the bleeder is ready when needed for dimmer compatibility
3Loss of energy
If the bleeder is disconnected in the absence of a dimmer circuit, then energy efficiency is improved, but the system cannot adapt to different types of dimmers without prior knowledge
Solution Approach 1:
The system employs self-service by automatically detecting the presence and type of dimmer circuit through analysis of mains voltage characteristics. The control circuit independently determines whether to activate or deactivate the bleeder based on its own measurements of voltage time intervals and differentials, eliminating the need for external configuration or prior knowledge of the lighting circuit type while optimizing energy efficiency and ensuring compatibility
Data Source
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AI summary
A method of controlling an electronic ballast for a lighting circuit, the electronic ballast comprising at least one bleeder, for use with dimmer circuits, is disclosed which method comprises: in response to a mains supply being connected to the lighting circuit, determining whether a dimmer circuit is present in the lighting circuit; and in response to determining that a dimmer circuit is not present, disconnecting the bleeder from the lighting circuit at least until the mains supply is disconnected. The method may be operable during a start-up phase, and the determination as to whether a dimmer circuit is present stored at least until the mains supply is disconnected. The determination, of either a leading or trailing edge phase cut dimmer, may be made by looking for a deviation from the expected sine-wave voltage, either directly through a temporal or voltage deviation, or indirectly by examining the second differential of the voltage with respect to time. An electronic ballast configured to operate such a method, and a lighting controller incorporating such a ballast, are also disclosed.