LED Driver Adaptation Circuit for Dimmer Compatibility
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Solution Overview
Problem
Existing drivers for light emitting diode (LED) lamps are not dimmer compatible, limiting their use with dimmers like triac dimmers, which results in inefficiencies and incompatibilities, especially concerning input current signals and power factor correction.
Innovation Solution
A driver with an adaptation circuit that adjusts instantaneous and average voltage signal ratios to make non-dimmer compatible systems dimmer compatible by using edge shapers, delay introducers, and top shapers to modify input voltage signal characteristics, and limiter and bleeder functions to improve dimmer compatibility and reduce harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a driver uses primary side regulation to reduce cost and complexity, then device complexity is reduced, but dimmer compatibility is lost
Solution Approach 1:
The patent introduces an intermediary adaptation circuit between the primary side regulation driver and the dimmer. This circuit includes edge shapers, delay introducers, and top shapers that condition the feedback signal to make it compatible with dimmer operation while keeping the main driver simple and cost-effective.
Solution Approach 2:
The patent segments the dimmer compatibility function into separate modular components (edge shaper, delay introducer, top shaper) that can be independently designed and optimized. This allows the main driver to remain simple while adding dimmer compatibility through discrete functional blocks.
2Adaptability or versatility
If the driver extends time intervals with high input current values to improve dimmer compatibility, then dimmer compatibility is improved, but total harmonic distortion increases
Solution Approach 1:
The patent carefully adjusts critical parameters including the delay time (e.g., 10-20 degrees), edge shaping thresholds, and top shaping levels to extend the conduction angle for dimmer compatibility while minimizing harmonic distortion. These parameter optimizations balance the conflicting requirements.
Solution Approach 2:
The adaptation circuit dynamically adjusts the feedback signal characteristics based on the instantaneous voltage waveform, creating variable time intervals for different portions of the AC cycle. This dynamic adjustment allows the system to maintain dimmer compatibility across varying operating conditions while controlling harmonic content.
3Adaptability or versatility
If the driver adapts instantaneous voltage values to improve dimmer compatibility, then dimmer compatibility is improved, but power factor correction performance deteriorates
Solution Approach 1:
The patent applies partial adaptation only to specific portions of the voltage waveform that are most critical for dimmer compatibility (edge regions and zero-crossing areas), while leaving the majority of the waveform intact to maintain power factor correction performance. This selective adaptation minimizes the impact on PF performance.
Data Source
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AI summary
Drivers (1) for driving lamps (2)comprising light emitting diodes are provided with arrangements (11) for, in response to detections of instantaneous values and average values of input voltage signals,providing output currents. Detected instantaneous values divided by detected average values form ratios. Adaptation circuits (12) for adapting some ratios make the drivers (1) dimmer compatible. The adaptation circuits(12) may comprise first circuits (21-29) for adapting the detected instantaneous values,second circuits (31-38) for adapting the detected average values, and third circuits (91-96) and fourth circuits (101- 5) for respectively modulating the detected average and instantaneous values to add bleeder functions. The adaptation circuits(12) may adapt the ratios in different ways during different parts of a period of the input voltage signal and such that a time-interval, during 10 which time-interval an input current signal of the driver (1) has instantaneous values larger than a threshold, is increased.